Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/misc/captions.txt

Text File | 1993-07-19 | 544KB | 9,341 lines

JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36521  MGN-1
                                        8/21/90

After traveling over 1.2 billion kilometers (780,000,000 miles), the
Magellan spacecraft was inserted into orbit around Venus on August 10,
1990.  This mosaic consists of adjacent pieces of two Magellan image strips
obtained on August 16, 1990 in the first radar test.  The radar test was
part of a planned In-Orbit Checkout sequence designed to prepare the
Magellan spacecraft and radar to begin mapping after August 31, 1990.  The
strip on the left was returned to the Goldstone Deep Space Station in
California, the strip on the right was received at the Deep Space Station
in Canberra, Australia.  A third station that will be receiving Magellan
data is located near Madrid, Spain.  Each image strip is 20 km (12 miles)
wide and 16,000 km (10,000 miles) long; this mosaic is a small portion 80
km (50 miles) long.

This image is centered at 21 degrees North latitude and 286.8 degrees East
longitude, southeast of a volcanic highland region called Beta Regio.  The
resolution of the image is about 120 meters (400 feet), 10 times better
than previous images of the same area of Venus, revealing many new geologic
features.  The bright line trending NW-SE across the center of the image is
a fracture or fault zone cutting the volcanic plains.  In the upper left
corner of the image, a multiple-ring circular feature of probable volcanic
origin can be seen, approximately 4.27 km (2.65 miles) across.  The bright
and dark variations seen in the plains surrounding these features
correspond to volcanic lava flows of varying ages.  The volcanic lava flows
in the southern half of the image have been cut by N-S trending faults.
This area is similar geologically to volcanic deposits seen on the Earth at
Hawaii and the Snake River Plains in Idaho, USA.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36522  MGN-2
                                        8/21/90

This portion of a Magellan radar image strip shows a small region on Venus
20 km (12.4 miles) wide and 75 km (50 miles) high, on the east flank of a
major volcanic upland called Beta Regio.  The image is centered at 23
degrees North latitude and 286.7 degrees East longitude.  The ridge and
valley network in the middle part of the image is formed by intersecting
faults which have broken the Venusian crust into a complex deformed type of
surface called tessera, the Latin word for tile.  The parallel mountains
and valleys resemble the Basin and Range Province in the Western United
States.

The irregular dark patch near the top of the image is a smooth surface,
probably formed by lava flows in a region about 10 kilometers (6 miles)
across.  Similar dark surfaces within the valleys indicate lava flows that
are younger than the tessera giving an indication of the geologic time
relationships of the events that formed the present surface.

The image has a resolution of 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36523  MGN-3
                                        8/21/90

This image shows a comparison between a Magellan image (right) and the
highest resolution Earth-based radar image of Venus, obtained by the U. S.
National Astronomy and Ionosphere Center Arecibo Observatory in Puerto
Rico.  The small white box in the Arecibo image on the left corresponds to
the Magellan image.

This portion of a Magellan radar image strip shows a small region on the
east flank of a major volcanic upland called Beta Regio.  The image is
centered at 23 degrees North latitude and 286.7 degrees East longitude.
The ridge and valley network in the mid part of the image is formed by
intersecting faults which have broken the Venusian crust into a complex
deformed type of surface called tessera, the Latin word for tile.  The
parallel mountains and valleys resemble the Basin and Range Province in the
western United States.

The irregular dark patch near the top of the image is a smooth surface,
probably formed by lava flows in a region about 10 kilometers (6 miles)
across.  Similar dark surfaces within the valleys indicate lava flows that
are younger than the tessera.

The Arecibo image contains probable impact craters, many faults, volcanic
flows, and tessera regions that will be mapped in detail by Magellan.

The Magellan image has a resolution of 120 meters (400 feet).  The image
segment is 20 km wide (12.4 miles) and 150 km (90 miles) long.  The Arecibo
image has a resolution of 1-3 km (0.6-1.8 miles) and is approximately 900
km (550 miles) across.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36529
                                        8/21/90

Multiple fracture systems in Devana Chasma, Phoebe Regio area.  These
fractures are in the central rift trough of Devana.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36530
                                        8/21/90

Tessera region east of Beta Regio.  Tessera is formed here by two
orthogonal fault systems.  The flows of the wider graben are covered by
more recent lava flows.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36531
                                        8/21/90

Fracture system extending north from Devana Chasma.  Same as #27.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36532
                                        8/21/90

Devana Chasma at 6 degrees north latitude, 288 degrees east longitude.
Steep walled fault troughs called graben indicate that this region is being
pulled apart forming a complex rift valley extending south from Beta Regio.
Volcanic flows appear to cover the flat floors of the graben in several
places.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36533
                                        8/21/90

Arecibo radar image (left) compared to Magellan.  Theia Mons in Beta Regio
is seen in the upper left corner of the Arecibo image.  The white line
shows the location of the Magellan image strip.  Magellan reveals a network
of intersecting fractures extending north from Devana Chasma.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36545  MGN-4
                                        8/23/90

This Magellan image mosaic shows the impact crater Golubkina, first
identified in Soviet Venera 15/16 data.  The crater is named after Anna
Golubkina (1864-1927), a Soviet sculptor.  The crater is about 34 km (20.4
miles) across, similar to the size of the West Clearwater impact structure
in Canada.  The crater Golubkina is located at about 60.5 degrees north
latitude, 287.2 degrees east longitude.  Magellan data reveal that
Golubkina has many characteristics typical of craters formed by a meteorite
impact including terraced inner walls, a central peak, and radar-bright
rough ejecta surrounding the crater.  The extreme darkness of the crater
floor indicates a smooth surface, perhaps formed by the ponding of lava
flows in the crater floor as seen in many lunar impact craters.  The radar-
bright ejecta surrounding the crater indicates a relatively fresh or young
crater.  Craters with central peaks in the Soviet data range in size from
about 10-60 km (6-36 miles) across.  The largest impact crater identified
in the Soviet Venera data is 140 km (84 miles) in diameter.

This Magellan image strip is approximately 20 km (12 miles) wide and this
piece of the image is approximately 100 km (62 miles) high.  The image is a
mosaic of two orbits obtained in the first Magellan radar test and played
back to Earth to the Deep Space Stations near Goldstone, California and
Canberra, Australia, respectively.  The resolution of this image is
approximately 120 meters (400 feet).  The see-saw margins result from the
offset of individual radar frames obtained along the orbit.  The spacecraft
moved from the north (top) to the south, looking to the left.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36546  MGN-5
                                        8/23/90

Two mosaicked pieces of Magellan image strips display the area east of the
Rhea Mons volcano on Venus.  This image is centered at about 32.5 degrees
north latitude and 286.6 degrees east longitude.  The mosaic is 47 km (28
miles) wide and 135 km (81 miles) long.  This region has been previously
identified as "tessera" from Earth-based radar (Arecibo) images.  The
center of the image is dominated by a network of intersecting ridges and
valleys.  The radar-bright north-south trending features in this image
range from 1 km (0.6 miles) to 3 km (1.8 miles) in length.  The average
spacing between these ridges is about 1.5 km (0.9 miles).  The dark patches
at the top of the image are smooth surfaces and may be lava flows located
in lowlands between the higher ridge and valley terrain.

This image is a mosaic of two orbits obtained in the first Magellan radar
test and played back to Earth to the Deep Space Stations near Goldstone,
California and Canberra, Australia, respectively.  The resolution of this
image is approximately 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36547  MGN-6
                                        8/23/90

This three-dimensional representation of brightness variations in a
Magellan radar image of Golubkina crater enhances the structural features
of the crater.  Golubkina is 34 km (20.4 miles) in diameter, and is located
at about 60.5 degrees north latitude, 287.2 degrees east longitude.
Golubkina is characterized by terraced inner walls and a central peak,
typical of large impact craters on the Earth, Moon and Mars.  The terraced
inner walls form at late stages in the formation of an impact crater, due
to collapse of the initial cavity formed by the meteorite impact.  The
central peak forms due to rebound of the inner crater floor.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36548  MGN-7
                                        8/23/90

This image of the Venusian crater, Golubkina, a 34 km (20.4 miles) diameter
impact crater located at about 60.5 degrees north latitude, 287.2 degrees
east longitude, contains Magellan data mosaicked with a Soviet Venera 15/16
radar image of the same feature.  The Magellan part of the image (right)
reveals details of the geology of the crater such as the central peak, the
inner terraced walls, and the extremely smooth floor of the crater.  The
smoothness of the floor may be due to ponding of volcanic lava flows in the
crater floor.  The rough, blocky morphology of the crater ejecta and the
sharp terraced crater wall suggest that this feature is relatively young.
The Soviet data have a resolution of 1-2 km (0.6-1.2 miles); the Magellan
data have a resolution of about 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36611  MGN-8
                                        9/12/90

Magellan radar image of part of the Phoebe region of Venus.  Mosaic of part
of revs 146 and 147 acquired in the first radar test on August 16, 1990.
The image is located at 292 degrees E. longitude, 24 degrees south
latitude.  This image is 30 km (19.6 miles) wide and 70 km (43.5 miles)
high.

This Magellan radar image of Venus shows an area to the southeast of Phoebe
Regio, an upland region characterized by major rift zones.  The irregular-
shaped depressions near the middle of the image are interpreted as volcanic
calderas, the larger of which is 8 x 3.6 km (5 x 2.2 miles) across.  Unlike
impact craters, volcanic calderas are not usually circular in map view.
Irregular calderas such as these occur on basaltic shield volcanoes on
Earth, such as those in Hawaii.  The radar illumination comes from the left
causing the caldera walls that face the spacecraft to be brightly
illuminated.  Another factor that makes the walls bright is that the walls
may be rough and blocky.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36612  MGN-9
                                        9/12/90

Magellan radar image of part of the Phoebe region of Venus.  Mosaic of part
of revs 146 and 147 acquired in the first radar test on August 16, 1990.
The image is located at 291 degrees E. longitude, 19 degrees south
latitude.  This image is 30 km (19.6 miles) wide and 76 km (47 miles) high.

On the basis of Pioneer Venus and Arecibo data, it is known that two major
rift zones occur in Southern Phoebe Regio and that they terminate at about
20-25S latitude about 2000 km apart.  This image is just north of the
southern end of the western rift zone.

This region is characterized by a complex geologic history involving both
volcanism and faulting.  Several of the geologic units show distinctive
overlapping or cross-cutting relationships that permit identification and
separation of geologic events and construction of the geologic history of
the region.  The oldest rocks in this image form the complexly deformed and
faulted, radar bright, hilly terrain in the northern half.  Faults of a
variety of orientations are observed.  A narrow fault trough (about one-
half to one km wide) is seen crossing the bright hills near the lower part
in the middle of the image.  This is one of the youngest faults in the
faulted, hilly unit as it is seen to cut across many other structures.  The
fault trough in turn appears to be embayed and flooded by the darker plains
that appear in the south half of the image.  These plains are interpreted
to be of volcanic origin.  The dark plains may be formed of a complex of
overlapping volcanic flows.  For example, the somewhat darker region of
plains in the lower left (SW) corner of the image may be a different age
series of plains-forming volcanic lava flows.  Finally, the narrow bright
line crossing the image in its lower part is interpreted to be a fault
which crosscuts both plains units and is thus the youngest event in the
sequence.  These relationships show the interplay of volcanic activity and
faulting that have influenced this region and a number of other regions on
Venus.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36613  MGN-10
                                        9/12/90

Magellan radar image of part of the Phoebe region of Venus.  Mosaic of part
of revs 146 and 147 acquired in the first radar test on August 16, 1990.
The image is located at 291 degrees E longitude, 20 degrees south latitude.
This image is 30 km (19.6 miles) wide and 76 km (47 miles) high.

This Magellan image shows a broad, up to 17 km (11 miles) wide, radar-
bright, lobate lava flow that extends 25 km NW across the image strip.  The
volcanic flow appears bright in this image because it is rough on a scale
of a few centimeters to a few meters (a few inches to a few yards), much
like lava flows on Earth that are called by geologists, aa (ah-ah), a
Hawaiian word that probably mimics the sound the ancients uttered while
running barefoot over the rough, jagged surface.  It is located near the SE
flank of Phoebe Regio and has flowed into local topographic lows.  This
lava flow has flooded the darker plains and appears to have buried N-S
trending lineaments that cut the darker material.  No obvious volcanic
sources are visible in this image.  The flow has a markedly uniform surface
texture in contrast to the more mottled texture of adjacent deposits; this
suggests it may represent the most recent in a series of eruptions that
subsequently have been obscured.  To the north and south are NW trending
graben that may belong to the system of fractures associated with Phoebe
Regio.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36642  MGN-11
                                        9/17/90

On September 15, 1990, the Magellan spacecraft started radar operations for
its mapping mission at Venus.  This image is taken from the first set of
radar data collected in the normal operating mode.  This Magellan radar
image is of an impact crater in the Navka Region of Venus.  The image is a
mosaic of data taken from orbits 376 and 377 on September 15, 1990.  The
crater is located at 334.5 E. longitude, 21.4 S. latitude, and is about 9 x
12 kilometers (5 x 7 miles) in size.  This crater is very unusual, and is
in some ways different from anything seen elsewhere in the solar system.
It is fresh, with a sharp rim, terraces on the walls, and a well-developed
ejecta blanket.  The rim, however, is distinctly kidney-shaped rather than
circular, and the crater's fresh appearance suggests, that it formed with
that shape at impact.  The ejecta blanket is markedly non-symmetric, with
lobes extending to the north (top) and south (bottom) of the image, and a
major extension stretching to the east (right).  On the crater floor are
several smooth, flat, dark regions.  The asymmetric shape of the ejecta
blanket has been observed on other planets and in impact experiments, and
probably indicates that the impactor struck the surface at a low, oblique
angle.  The impactor would have been moving from west to east, sending
ejecta lobes off to either side and a long streamer in the forward
direction.  The truly unusual aspect of the crater is its shape.  One
possible explanation is that the impactor broke up as it passed through the
dense Venusian atmosphere, causing several large chunks of material to
strike the surface almost simultaneously in an irregular pattern.  The dark
patches on the crater floor may be solidified pools of molten rock
generated by the impact, or could be volcanic material extruded some time
after the crater's formation.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36643  MGN-13
                                        9/17/90

On September 15, 1990, the Magellan spacecraft started radar operations for
its mapping mission at Venus.  This image is taken from the first set of
radar data collected in the normal operating mode.  This Magellan radar
image is of part of the Danu Montes in the Lakshmi Region of Venus.  The
mosaic is part of orbits 376, 377, and 378 acquired on the first day of
nominal mapping, September 15, 1990.  The image is located at 329.6 degrees
E longitude and 58.75 degrees N latitude.  This image is 40 kilometers
(19.6 miles) wide and 60 kilometers (39.2 miles) high.  Danu Montes is a
mountain belt located at the southern edge of the Ishtar Terra highland
region.  It rises one to three kilometers above a flat plain to the north
known as Lakshmi Planum.  Lakshmi Planum contains several large volcanoes
and abundant plains of volcanic origin.  To the south of Danu Montes is a
scarp (Vesta Rupes) marking the southern edge of Western Ishtar Terra.  At
the scarp the topography descends about two kilometers to the surrounding
lowlands.  On the basis of Pioneer Venus, Arecibo, and Venera data, Danu
Montes and the other mountain belts surrounding Lakshmi Planum have been
interpreted to be orogenic belts marking the focus of compressional
deformation, much like the Appalachians and Andes on Earth.  In the upper
right part of this image, relatively bright, smooth-textured plains of
Lakshmi Planum are seen to embay the heavily deformed mountain region to
the south.  In the mountain range south of these plains the geology is
dominated by abundant faults at multiple angles and showing various cross-
cutting relationships.  In the northern part of the mountain the surface is
dominated by sinuous, west-northwest trending troughs less than a kilometer
(0.6 miles) in width, separated by narrow, flat regions.  Further south are
flat-floored features similar to extensional graben on Earth.  These graben
are up to 2 kilometers (1.3 miles) in width.  The prominent bright and dark
feature trending across the bottom part of the image is a linear trough
about 5 kilometers wide (3.1 miles) located near the crest of the mountain
range.  South of the mountain crest, additional deformation is seen
trending both parallel and perpendicular to the structures in other parts
of the mountain belt.  These patterns represent the complex tectonic
deformation involved in the formation of the mountain ranges, and the
graben-like features may represent extension associated with the
gravitational collapse of the mountains subsequent to their initial
formation.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36644  MGN-12
                                        9/17/90

On September 15, 1990, the Magellan spacecraft started radar operations for
its mapping mission at Venus.  This image is taken from the first set of
radar data collected in the normal operating mode.  These fault-bounded
troughs were imaged by Magellan on orbit 147 on September 15, 1990.  The
image is of part of the Lavinia Region of Venus at 60 degrees south
latitude, 347 degrees east longitude.  The image is 28 kilometers (17
miles) wide and 75 kilometers (46 miles) long.  This region is at the
intersection of two tectonic trends.  An extensive set of east-west
trending fractures extends to the west (left) and a second set extends down
to the south-southeast (lower right).  The lines of pits suggest some
igneous or volcanic activity accompanying the faulting.  The prominent
trough trending diagonally across the image is 5 kilometers (3.1 miles)
wide and is 100 to 200 meters (300 to 600 feet) deep.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36655
                                        9/19/90

This image is part of the Helen Region of Venus.  The image was obtained by
the Magellan radar on August 16, 1990 during a radar test.  The location is
at 26.1 degrees south latitude, 292 degrees east longitude.  The image
segment is 47 kilometers (29 miles) wide and 77 kilometers (48 miles) in
length.  This area illustrates the complex nature of some of the plains.
At least two directions of faulting can be seen in the bright linear
patterns.  The cross fracture pattern is usually associated with high
relief, rugged terrain of tessera regions.  In this location, however,
there appears to be little relief associated with the fracturing.  A clue
to the interpretation of this region lies in the numerous circular to
irregular depressions ranging in size from 500 m (0.3 mile) to 1.5
kilometer (0.9 mile).  These depressions appear to be volcanic calderas and
are probably associated with extensive volcanic flows that have flooded the
tessera.  Another probable volcanic feature is the small mound
approximately 1.9 kilometer (1.2 mile) in diameter on the right side of the
picture in the lower half.  The bright lines can be interpreted as fracture
or fault traces.  The fact that they tend to occur in pairs of lines spaced
500 m (0.3 miles) to 1.5 kilometer (0.9 miles) apart suggest that the lines
delineate flooded graben, or fault valleys that have been filled with
volcanic flows.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36656
                                        9/19/90

This view of the surface of Venus acquired by the Magellan spacecraft shows
a geologically young region of lowland plains.  The location is near the
equator between two highland areas known as Asteria Regio and Phoebe Regio.
Illumination in the radar image is from the left (west); in this
transformed version the viewer looks due north with a slant angle about 10
degrees.  The region seen is about 40 kilometers (24 miles) wide and
stretches 600 kilometers (360 miles) down range to the north.  Complex
canyon systems that trend northeast and northwest were produced as Venus'
crust was pulled apart by extensional forces.  Some were filled with
younger lava flows.  The canyons are typically 5 to 10 kilometers (3 to 6
miles) wide, 50 to 100 kilometers (30 to 60 miles) long and rimmed by fault
scarps a hundred meters or so high.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36657
                                        9/19/90

This mosaic is made up from Magellan orbits 146 and 147, obtained on August
16, 1990 in the Helen region of the southern hemisphere of Venus and
centered at 36.5 degrees south latitude, 293.3 degrees longitude.
Resolution of the Magellan data is about 120 meter (400 feet).  The mosaic
is about 40 kilometers (24 miles) wide and about 80 kilometers (50 miles)
long, and shows a portion of a corona in a highland region called Themis
Regio.  Coronae are large [>250 kilometers (150 miles) across] circular
structures surrounded by a ring of ridges.  Coronae were first identified
in Soviet radar images of Venus.  Coronae usually average about 1 kilometer
(0.6 mile) high, and are thought to form due to the rise of hot material
from the interior of the planet, similar to Hawaii on the Earth.  The
mosaicked Magellan images show the interior of the corona and a portion of
its rim.  Ridges appear to radiate out from the center of the corona,
perhaps produced due to extensional stresses caused by uplift of the
surface.  Geologists and geophysicists will be analyzing the morphology,
spacing, and topography of this complex tectonic feature to understand more
about the origin of coronae and how they relate to similar features on
Earth.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36658
                                        9/19/90

On September 15, 1990, the Magellan spacecraft started radar operations for
its mapping mission at Venus.  This image is taken from the first set of
radar data collected in the normal operating mode.  This Magellan radar
image is part of the southern Lavinia Planitia region of Venus obtained
during orbit 377.  The center of the image is at 356 degrees east
longitude, 68.7 degrees south latitude.  The image is 30 kilometers (18
miles) wide and 70 kilometers (43 miles) long.  On the basis of Arecibo
data it is known that these features are located near the center of a large
oval-shaped deformation structure, known as a corona, 775 kilometers (480
miles) in diameter adjacent to east-northeast trending linear features.
The center of this corona is the focus of abundant lava flows extending
hundreds of kilometers into the surrounding plains.  The Magellan image
reveals the details of this central volcanic source region.  The Magellan
image is characterized by an egg-shaped fault-bounded depression (center
left of the image) interpreted to be a volcanic caldera, a radar-bright
lobate deposit interpreted to be a volcanic flow, and multiple east-west
trending bright linear structures interpreted to be fault scarps and
troughs.  Calderas form from the withdrawal of molten rock from a chamber
below the surface and collapse of the overlying rocks.  The egg-shaped
caldera shows evidence of two stages of collapse.  The outer boundary,
which appears to have a slightly raised rim, is 8 x 10 kilometers (5 x 6
miles) in diameter; the inner boundary is 5 x 6 kilometers (3 x 4 miles) in
diameter.  The floor of the caldera is 4 x 6 kilometers (2.5 x 4 miles) in
diameter and appears smooth.  The part of the bright lava flow seen in this
image (just south of the caldera) is 30 kilometers (18 miles) long and 2-12
kilometers (1.25-7.5 miles) wide.  Various features often associated with
lava flows are observed.  Features resembling raised levees are observed
along the edges of the flow in the western part of the image.  Lobate
extensions of the flow are observed in a direction towards the caldera.  A
variety of cross-cutting relationships of linear structures and the flow
are observed.  On Earth, such linear features are often the sources of
flows.  The linear feature north of the caldera extends across the width of
the image, is approximately 2 kilometers (1.25 miles) wide, and appears to
be a trough that tapers to the east.  The linear features to the south of
the caldera extend from 13 to at least 30 kilometers (8-18 miles) across
the image and are 1-2 kilometers (.62-1.24 mile) wide.  These features may
represent fault scarps or troughs, and are likely associated with the
movement of subsurface magma and the formation of the large corona in which
these features occur.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36697  MGN-14
                                        9/25/90

This is a Magellan image mosaic of an impact crater located in Guinevere
Planitia with a rim diameter 12.5 kilometers (7.8 miles).  The mosaic is
located at 6 degrees north latitude , 335 degrees longitude, and is from
orbits 376 and 377 obtained on September 15, 1990.  The image is about 37
kilometers (23 miles) wide and 80 kilometers (48 miles) long.  Material
thrown out from the impact forms a bright ejecta blanket surrounding most
of the crater.  The object that formed this crater was probably moving
toward the north (top of picture) at a shallow angle to the surface when it
hit.  The two lines of evidence that support this view are the "missing
ejecta" on the south and the small secondary craters seen to the north.
The secondary craters are formed by large blocks thrown out of the primary
crater.  Most of the larger blocks landed close to the crater rim, while
finer material traveled farther, creating a radial pattern.  The inside of
the crater shows terracing caused by slumping of the inner wall.  A complex
central peak is also seen; it was formed by uplift of the ground when it
rebounds following impact.  Resolution of the Magellan data is about 120
meters (400 feet).
PUBLIC INFORMATION OFFICE
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PHOTO CAPTION                           Magellan
                                        P-36698  MGN-15
                                        9/24/90

This Magellan image shows an area 40 kilometers (25 miles) by 112 km (70
miles) to the northeast of Ushas Mons on Venus.  It was obtained on
September 16, 1990 when the spacecraft was on its 384th orbit of the
planet.  This image shows evidence of possible explosive volcanism and
eolian or wind activity.  The image shows two types of plains - fractured
and smooth.  The smooth plains in the center of the image appear to overlay
the fractured plains.  Extending from the one kilometer (0.6 mile) diameter
crater in the middle of the image is a radar-bright fractured surface that
broadens away from the crater.  It is brighter near the crater and fades
gradually into smooth plains at its distal end 10 kilometers (6 miles) from
the crater.  A similar but darker deposit extends away from the crater to
the left.  These streaks are interpreted to form due to the scouring away
of the smooth plains deposit by the wind, revealing the fractured plains
below.  The smooth plains deposit and the craters may have formed by
fallout from volcanic explosion plumes.  Their characteristics are typical
of terrestrial pyroclastic volcanic deposits.  Resolution of the Magellan
data is about 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36699  MGN-16
                                        9/25/90

This is a Magellan radar image mosaic of part of the Lakshmi region of
Venus.  The mosaic is part of revolutions 390 and 391 acquired on September
17, 1990.  The image is located at 30 degrees north latitude, 333.3 degrees
east longitude, and is about 37 kilometers (23 miles) wide and 80
kilometers (48 miles) long.  On the basis of Pioneer Venus and Arecibo
data, it is known that the region shown is located on the low rise
separating Sedna Planitia and Guinevere Planitia, and just to the west of
Eistla Regio.  The image shows two sets of parallel lineations which
intersect almost at right angles.  The fainter lineations are spaced at a
regular interval of about 1 kilometer and extend beyond the boundaries of
the image.  The width of these faint lineations is at the limit of
resolution of the best Magellan images.  The brighter, more dominant
lineations are less regular and appear in places to begin and end where
they intersect the fainter lineations.  It is not yet clear whether the two
sets of lineations represent faults or fractures, but in other areas
outside the image, the bright lineations are associated with pit-craters
and other volcanic features.  This type of terrain has not been seen
previously, either on Venus or the other planets.  Resolution of the
Magellan data is about 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36700
                                        9/25/90

This Magellan image from orbit 376 shows about two-thirds of the well-
preserved impact crater Lyudmila (Russian first name).  The crater is 13.7-
kilometers (8.2 miles) in diameter and is located in a nearly featureless
region of Lakshmi Planum in Ishtar Terra at latitude 62.2, longitude 329.8.
Lyudmila, identified from Venera 15/16 images as being a possible impact
crater by Soviet scientists, is shown on Magellan's high resolution images
to have the rough inner and smooth outer ejecta deposits that are
characteristic of impact craters observed throughout the Solar System.  The
outer ejecta, resembling the petals of a daisy, extends a maximum of 13.3
kilometers (8 miles), or about one crater diameter, from the crater rim.
Lyudmila also has additional characteristics of impact craters, including
terraced inner walls, and a central peak.  The darkness of much of the
crater floor indicates a smooth surface, perhaps formed by the ponding of
lava flows in the crater floor.  The radar-bright ejecta of the crater may
indicate that the crater is relatively young or fresh.  The resolution of
this image is approximately 120 meters (400 feet).  The spacecraft moved
from the north (top) to the south, looking to the left.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36701
                                        9/25/90

This image from Magellan's 383rd orbit of Venus shows about half of an
unnamed 47 kilometers diameter (28 miles) impact crater; it is the second
largest of three similar craters closely grouped in a region of radar-dark
(smooth) plains between Lavinia Planitia and Guinevere Planitia.  The
crater, located at latitude 26.4 degrees S. and longitude 337.3 degrees,
was previously seen in Earth-based radar images acquired at the Arecibo
radar observatory in Puerto Rico.  The crater has many characteristics
typical of meteorite impact craters, including a central peak, deposits of
hummocky or hilly material immediately surrounding the crater's rim, and
smoother more patchy deposits that extend further from the crater rim.
Some of the hummocky ejecta appears to extend for some distance along the
major lobes formed by the outer ejecta.  This radial distribution of the
hummocky ejecta may be a consequence of the way the material was thrown
from the crater and moved through the atmosphere and along the surface.
The crater's central peak, and flat floor are also common to many other
impact structures; the latter probably formed by the ponding of lava flows
on the crater's floor.  Secondary impact craters formed by far-flung
ejecta, are also present near the most distal parts of the outer ejecta
deposits.  The radar-bright ejecta and inner wall of this crater indicate
that it is fresh and not noticeably degraded.  The resolution of this image
is about 150 meters (450 feet); north is to the top.  The Magellan radar
was illuminating the surface from left to right in this image.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36702
                                        9/25/90

This dark plains region is of a part of the Lavinia Region in the southern
hemisphere at 29.1 degrees south latitude and 337 degrees east longitude.
This image is of an area 45 kilometers (28 miles) wide and 77 kilometers
(48 miles) long.  It shows a variety of features, including volcanic domes
and pits, linear fractures, and high-standing mesas bounded by steep
cliffs.  A bright streaky deposit at the base of the steep cliffs in the
upper right indicates downslope movement of material, and possible erosion
of accumulation of windblown debris.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36703
                                        9/25/90

This Magellan image of the Lakshmi Region of Venus was taken on September
15, 1990.  The image is a mosaic of orbits 376 and 377 and shows features
on the surface of Venus at 36 north latitude, 330 east longitude.  The
image measures 41 x 77 kilometers (25 x 48 miles) and shows the dark
randomly fractured plains of Sedna Planitia.  The circular feature in the
center of the image is a relatively flat-topped dome, 13 x 20 kilometers (8
x 12.5 miles) in diameter at the top and 28 by at least 35 kilometers (17 x
22 miles) in diameter at the base.  The top of the dome is highly fractured
in a radial pattern; wider troughs extend downslope on the north and
southeast flanks.  The fractures in the plains deflect in a circumferential
pattern around the base of the dome.  A similar pattern to the west of the
dome indicates the presence of a second dome to the left, off the image.
Since no lava flows are observed to emanate from the dome, this feature may
be a failed volcano, known as a "cryptodome".  Cryptodomes form on Earth
when molten rock rises but is unable to break through to the surface as
lava flows.  The overlying rock is bowed up, possibly fracturing the
surface and forming a flat-topped dome.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36704
                                        9/25/90

This scene, which covers an area of 75 kilometers (46 miles) by 45
kilometers (28 miles), shows an area of dark volcanic lava flows overlying
the brighter surrounding plains which are thought to have been formed from
older flows.  Some of the dark flows terminate on the narrow bright sinuous
feature to the right of the image and it is assumed that they originate
from eruptions at fissures located along this bright feature.  The image is
located at latitude 4.6 degrees North and longitude 331.8 East.  The
horizontal banding is a processing artifact in this photo made from the
first orbit after the start of systematic mapping.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36705
                                        9/25/90

At least a dozen volcanic domes can be seen in this 75 kilometer (46 miles)
by 45 kilometer (28 miles) area on Venus located in a plains region at
latitude 25.0 degrees north and longitude 330.6 degrees east.  Several of
them have small summit craters.  Five of them also exhibit a slightly
brighter area stretching south-west from the dome into the surrounding
plains.  It is thought that this is indicative of a local wind direction of
north-east to south-west, although the mechanism responsible for the
brightening is not understood.  It may be due to pyroclastic material
ejected from the volcano and carried downwind or to the bright area having
a different surface texture due to it lying in the wind shadow of the
mountain.  If these bright areas are indicative of the local wind
direction, then it may be possible to use them to map the global wind
patterns.  Steep slopes and small scale surface roughness associated with
fractures are thought to be responsible for the bright lineament pattern in
the plains surrounding the domes.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36706
                                        9/25/90

This Magellan image shows a radar dark lava flow to the southeast of Navka
Planitia.  The image was obtained on spacecraft orbit 377 and lies on 3.5
degrees north latitude, 335 degrees longitude.  Resolution of the Magellan
data is about 120 meters (400 meet).  This image is about 40 kilometers (24
miles) wide and about 80 kilometers (48 miles) long.  The flow is over 30
kilometers (18 miles)long and 1-2 kilometers (0.6-1.2 miles) wide and
appears to have been formed from relatively fluid lava.  Magellan images
show a wide variety of volcanic landforms indicating different styles of
volcanism.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36707
                                        9/25/90

This is a Magellan radar image of an area near the crest of the Danu
Montes, a mountain range in the Lakshmi region of the planet.  The area
imaged is centered at latitude 58.3 degrees North, longitude 332.5 degrees.
The data were taken on orbits 390 and 391 on September 17, 1990, and cover
an area about 75 kilometers (45 miles) high by 30 kilometers (20 miles)
wide.  The dominant structures of the Danu Montes in this area are very
complex ridges, troughs, and elongate blocks running from WNW to ESE.
Found among these features in this image, however, are two types of
collapse features, one simple and one rather complex.  The simple one
occurs near the top of the image, and consists of a chain of partially-
coalesced pits, aligned along the dominant WNW-ESE structural trend of the
region.  The complex one, near the center, consists of a long, flat-floored
depression that runs perpendicular to the regional trend, with two other
elongate depressions that lie parallel to the trend and crosscut it.  The
nature of this crosscutting shows that the feature perpendicular to the
regional trend formed before the ones crosscutting it.  Collapse features
of this sort can form as a result of withdrawal of magma from below the
surface and may indicate that formation of the Danu Montes was accompanied
by volcanic activity.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36708
                                        9/25/90

This image was obtained on Sunday, September 16 by the Magellan spacecraft
in orbits 383 and 384.  The area is centered at 41.4 degrees south
latitude, 340.4 degrees east longitude, in the Lavinia Region.  The image
is 40 kilometers (25 miles) wide, and 70 kilometers (43 miles) long.  This
region shows three NW trending, rough, bright bands spaced about 25
kilometers (15 miles) apart, each characterized by intense geologic
deformation.  The northernmost part of the image is the least bright of the
three bright bands, with several slightly sinuous lineaments trending NW.
The middle band has a much brighter concentration of straight lineaments,
and some troughs ranging from 300 to 2000 meters (900-6000 feet) in width.
The southern band has much more sinuous, anastomosing lineaments, which
trend NW to NNW.  The intervening areas are dark and smooth with only a few
bright lineaments, which trend both NW and NE.  This image shows two
distinct scales of deformation: the bands themselves, which lie many
kilometers apart, and the individual faults within the bands, which are
much more closely spaced.  The fine-scale deformation may indicate faulting
that is concentrated very close to the surface, while the organization of
the deformation into regular bands may suggest the presence of deeper
layering in the crust.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36709
                                        9/25/90

This image was obtained on Saturday, September 15 by the Magellan
spacecraft in orbits 376 and 377.  The area is centered at 36.4 degrees
south latitude, 337.9 degrees east longitude, in the Lavinia Planitia
region.  The image is 37 kilometers (23 miles) wide, and 79 kilometers(48
miles) long.  Narrow troughs, sinuous ridges and a broad arch are common in
this area of otherwise smooth plains.  The ridges and arches trend NNW and
the arch is up to 5 kilometers (3 miles) wide.  Most of the troughs trend
WNW and are about 400-800 meters (1200-2500 feet) wide.  The ridges and
arch are similar to wrinkle ridges which are abundant in the lunar maria.
Such wrinkle ridges consist of ridges and broad arches which formed in the
smooth lava plains when the surface of the maria subsided and shortened.
The similarity between wrinkle ridges and the ridges in this image suggests
that this area has experienced a small amount of horizontal contraction.
The small troughs may represent extension in the orthogonal direction.  If
the extension was contemporaneous with the compression, then a small amount
of left-lateral shear oriented NW-SE is implied.
36710
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36711  MGN-17
                                        9/25/90

One of the most useful Magellan standard data products is the full
resolution mosaic, the F-MIDR (Full-Resolution Mosaicked Image Data
Record).  These products are mosaics of about 500 km (300 mile) segments of
30 or more individual image strips.  This is a partial F-MIDR made from
orbits 376 to 399, obtained between September 15 and September 18, 1990,
part of the first orbits in which the Magellan flight team operated the
radar system in the mapping mode.  The mosaic is centered at 27 degrees
south latitude, 339 degrees longitude, in the Lavinia region of Venus.
Three large impact craters with diameters ranging from 37 kilometers (23
miles) to 50 kilometers (30 miles) can be seen located in a region of
fractured plains.  The craters show many features typical of meteorite
impact craters, including rough, radar-bright ejecta, terraced inner walls
and central peaks.  Numerous domes of probable volcanic origin can be seen
in the southeastern corner of the mosaic.  The domes range in diameter from
1-12 kilometers (0.6-7 miles), and some have central pits typical of
volcanic shields or cones.  Resolution of the Magellan data is about 120
meters (400 feet).
36735
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36837
                                        10/11/90

This Magellan image is a mosaic of data obtained during orbits 377-399.
The image is 284 kilometers (176 miles) wide at the top and 250 kilometers
(155 miles) wide at the bottom.  It is approximately 575 kilometers (356
miles) long.  The image is centered at 60 degrees south latitude and 349.6
degrees east longitude.  The area shown is located within the Lavinia
Region of Venus in northern Lada Terra.  In the lower half of the image is
an extensive system of fault scarps and graben trending NW-SE.  These
linear structures extend up to 300 kilometers (186 miles) in length and are
70 meters (0.04 miles) to 7 kilometers (4 miles) in width.  The northern
ends of the features often widen to become elongate collapse pits and
calderas, 2-30 kilometers (1-18 miles) in diameter.  A second set of linear
features trending E-W is observed in the upper left portion of the image.
The exact nature of these structures is unclear, although some appear to be
graben.  The formation of the linear features seen in this image may be
linked to subsurface magma injection along dikes, subsequent drainage and
collapse.  At the intersection of these two sets of linear structures is a
large quasicircular feature approximately 215-140 kilometers (135-87 miles)
in diameter defined by partial arcs of semiconcentric curvilinear
structures including fault scarps and graben.  It is interpreted to be a
corona, formed by large-scale magma upwelling from the interior of Venus.
Within the corona are numerous volcanic domes and pits 2-5 kilometers (1-3
miles) in diameter, volcanic flows, and a sinuous depression approximately
47 kilometers (29 miles) long.  A shield volcano 19 kilometers (12 miles)
in diameter with a 1 kilometer (0.6 mile) diameter summit pit is observed
near the SE boundary of the corona.  The missing strip of this image is
being reprocessed to remove artifacts.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36838
                                        10/11/90

The first 3 days (24 orbits) of radar mapping from the Magellan spacecraft
have revealed the presence of a wide diversity of geologic features on the
surface of Venus.  This full resolution mosaic centered at 20 south
latitude, 337.4 east longitude is located between Navka and Lavinia
Planitia and covers a region 475 kilometers (285 miles) wide and 545
kilometers (330 miles) long.  Analysis of this area from lower resolution
Arecibo data show that this area is part of an extensive region identified
as bright plains.  The Magellan data reveal the detailed geologic
characteristics of different landforms in these plains.  Located along the
left central edge of the image is a cluster of volcanic domes which range
from 1.5 kilometers to 7.5 kilometers in diameter and cover a region 150
kilometers by 100 kilometers (90 miles by 60 miles).  The domes and their
deposits are located at the convergence of radar-bright lineaments which
are interpreted to be faults and troughs.  In some places the domes overlie
the faults.  The faults and troughs extend into the lower part of the image
where they terminate against dark plains deposits and are cross cut at
right angles by additional faults.  These relations indicate that multiple
episodes of faulting and volcanism have occurred.  An irregular shaped
impact crater (11 kilometers by 8 kilometers) (7 miles by 5 miles) located
in the lower left corner of the image is interpreted to have formed by
multiple impacts resulting from the breakup in the atmosphere of a larger
impactor.  An extremely radar-dark circular region located along the right
central edge of the image is interpreted as a possible region of
sedimentary deposits.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36850
                                        10/11/90

This image shows the southern extent of the elevated plateau Lakshmi Planum
located in the northern high latitudes of Venus.  The radar data was
collected by the Magellan spacecraft between the dates September 15-18,
1990 and consists of 24 mosaicked orbit tracks.  The area covered in this
image is approximately 540 kilometers (335 miles) by 275 kilometers (171
miles).  Lakshmi Planum proper is demarked by relatively homogeneous
volcanic deposits which make up the northern two-thirds of this image.
Notable features on Lakshmi include the impact crater Lyudmila (upper left
portion of the image).  To the east of Lyudmila are some relatively radar
bright lava flows probably associated with the nearby Sacajawea caldera.
Lakshmi Planum is rimmed to the south by the Danu Montes mountain belt
which is seen as a radar-bright semi-circular band in the lower part of the
image.  Danu Montes rises approximately 450 meters (1476 feet) above
Lakshmi Planum.  Extension of the mountain range is expressed as northwest-
southeast trending troughs or graben which appear as distinct radar-dark
features in western Danu Montes.  The topography drops very sharply (2.8
kilometers or 1.7 miles) south of Danu Montes.  Southwest of Danu Montes is
the highly fractured relatively radar-dark plains of Vesta Rupes.  The
southeasternmost corner of the image is another terrain known as Clotho
Tessera.  Tessera (from the Latin word meaning "tile") is a highly deformed
type of terrain which is comprised of multiple intersecting structural
trends.  Interestingly, the boundary between Danu Montes, Vesta Rupes, and
Clotho Tessera is marked by the presence a circular feature (located at
approximately 57.9 degrees north / 333.0 degrees east) whose exact origin
is unclear.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36908  MGN-24
                                        10/25/90

This image is a mosaic of 24 Magellan orbits of Venus over the Ishtar Terra
region.  The image is centered at about 55 degrees north latitude and 335
degrees east longitude, and is about 300 kilometers (180 miles) across.
The mosaic covers the western part of Clotho Tessera, first identified in
Soviet Venera 15/16 radar images of Venus.  The region is dominated by a
network of intersection ridges and valleys indicating a complex history of
intense deformation.  Domes, pits, and smooth, dark plains regions within
the tessera indicate that volcanism has also been an active process in this
region.  Researchers on the Magellan project are mapping this region in
detail in order to unravel the styles and sequence of deformation in
Clotho.  Resolution of the Magellan data is approximately 120 meters (400
feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-36909
                                        10/25/90

This image is a mosaic of 24 orbits of the Navka region of Venus.  The
image is centered at about 10 degrees south latitude and 335 degrees east
longitude.  The image is about 400 km (240 miles) across.  "Behepa 8" marks
the approximate landing site of the Soviet Venera 8 lander, which took
measurements at the surface of Venus in 1972.  The Venera 8 lander measured
granitic or continental-like materials at the landing site.  Magellan data
reveals the landing site to lie in a region of plains cut by tectonic
ridges and troughs.  Volcanic domes and flows are seen throughout the
region.  Studying the regional setting of the Venera landing sites is
important in linking information about surface composition to surface
morphology seen in radar images.  Resolution of the Magellan data is about
120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37047
                                        11/7/90

This composite image was created by inserting approximately 70 orbits of
Magellan data into an image obtained at the Arecibo, Puerto Rico
radiotelescope and shows a geologically complex region in the southern
hemisphere of Venus.  The region is centered on 65 degrees south, 359
degrees east and is about 1500 x 1500 km (900 x 900 miles) in extent.  The
large oval feature in the lower half of the image is Quetzalpetlatl Corona,
approximately 700 km (420 miles) in diameter.  Coronae are circular to oval
regions defined by an annulus of ridges and are centers for tectonic and
volcanic activity.  Tectonic activity is largely observed in a relatively
narrow rim region, which in this image is defined by a complex lineated
terrain that surrounds much of the corona.  Bright and dark volcanic flows
are seen throughout the corona and surrounding terrain.  Small shield
volcanoes, 1-20 km (0.6-12 miles) in diameter, are seen near the southern
limit of the Magellan data in the image.  Narrow linear troughs (seen in
the image as bright lines) trend to the north-northwest of Quetzalpetlatl.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37047, 1A
                                        11/13/90

This image shows a flooded impact crater, several collapse features, and
lava flows to the south of Lavinia Planitia in the southern hemisphere.
Centered at 60 degrees S, 352 degrees E, the image covers an area of
approximately 300 x 500 km (180 x 300 miles).  The impact crater is 65 km
(39 miles) in diameter and was originally about 500 meters (1300 ft) deep
but has been almost completely buried by lava flows, leaving only the rim
and the southeastern part of the bright, rough ejecta deposit.  Recent lava
flows appear as bright or dark regions with sinuous boundaries.  Collapse
features are linear or sinuous valleys which range from 200 meters (650
feet) to 5 km (3 miles) in width and are up to 100 km (60 miles) long.
These valleys may form when subsurface magma drains along tectonic
fractures, allowing the overlying surface to collapse.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37047, 2A
                                        11/7/90

The northern rim of Quetzalpetlatl Corona is shown in this image.  The
region is approximately 450 km (270 miles) on a side and is centered on 64
degrees S, 359 degrees E.  The rim has a hummocky, rough texture, ranges
from 50 to 100 km (30 to 60 miles) in width, and rises up to 1 km (0.6
miles) above the bright lava flows to the north.  In the eastern part of
the image, the rim has been transected by numerous north-south trending
extensional features, which are partially flooded by volcanic plains.
Understanding the complex interrelationships between episodes of volcanism
and tectonism will aid in unraveling the origin of coronae.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37047, 3A
                                        11/7/90

This 60 x 100 km (36 x 60 miles) region is centered on 64 degrees S, 356
degrees E and shows lava flows that have ponded up against the rim of
Quetzalpetlatl Corona.  The smooth, radar bright flows partially fill a
topographic trough that extends to the west and lies parallel to the rim of
the corona.  The flows are relatively young and appear to cover parts of
both the rim of the corona and NW-SE trending fractures that lie to the
north of the flow.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37047, 4A
                                        11/7/90

The interior of Quetzalpetlatl Corona is a region of intense volcanic
activity.  This image is centered on 69.5 degrees S, 4 degrees E and shows
a 100 x 150 km (60 x 90 mile) area containing numerous small shield
volcanoes.  The volcanoes range from 1-20 km (0.6-12 miles) in diameter and
are strongly concentrated in an area that also contains some of the highest
elevations in the corona.  Bright and dark patches in the image represent
flows of varying roughness, with bright regions being relatively rough and
dark regions relatively smooth.  Some of the volcanoes and part of the
surrounding plains are dissected by valleys which appear to result from the
withdrawal of subsurface magma and subsequent collapse of overlying rocks.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37125  MGN-18
                                        11/16/90

This image of the eastern edge of Alpha Regio, 30 degrees south latitude,
11.8 east longitude, was acquired on November 7, 1990.  It shows seven
circular domical hills averaging 25 kilometers (15 miles) in diameter and
maximum heights of 750 meters (2475 feet).  These features can be
interpreted as viscous or thick eruptions of lava coming from a vent on the
relatively level ground allowing the lava to flow in an even lateral
pattern.  The concentric and radial fracture pattern on their surfaces
suggests if they are extrusive that a chilled outer layer formed then
further intrusion in the interior stretched the surface.  The domes may be
analogous to volcanic domes on Earth.  An alternative interpretation is
that the domes are the result of shallow intrusions up-doming the surface
layers.  If they are intrusive, then magma withdrawal near the end of the
eruptions then produced the fractures.  The bright margins possibly
indicate the presence of rock debris or talus at the slopes of the domes.
Fractures on the surrounding plains are both older and younger than the
domical hills.  Resolution of the Magellan data is about 120 meters (400
feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37128
                                        11/16/90

This Magellan image shows a complex crater, 31.9 km (20 miles) in diameter
with a circular rim, terraced walls, and central peaks, located at 20.3
degrees north latitude and 331.8 degrees east longitude.  Several unusual
features are evidenced in this image: large dark surface up range from the
crater; lobate flows emanating from crater ejecta, and very radar-bright
ejecta and floor.  Aurelia has been proposed to the International
Astronomical Union, Subcommittee of Planetary Nomenclature as a candidate
name.  Aurelia is the mother of Julius Caesar.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37128  MGN-26
                                        11/19/90

This Magellan image shows a complex crater, 31.9 kilometers (20 miles) in
diameter with a circular rim, terraced walls, and central peaks, located at
20.3 degrees north latitude and 331.8 degrees east longitude.  Several
unusual features are evidenced in this image: large dark surface up range
from the crater; lobate flows emanating from crater ejecta, and very radar-
bright ejecta and floor.  Aurelia has been proposed to the International
Astronomical Union, Subcommittee of Planetary Nomenclature as a candidate
name.  Aurelia is the mother of Julius Caesar.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37129
                                        11/20/90

This image is 50 kilometers (30 miles) across and 75 kilometers (45 miles)
from top to bottom in the plains south of Clotho Tessera in the Ishtar
Region.  It is centered at approximately 53 degrees north, 332 degrees
east.  The bright and dark lineations seen throughout the image are
fractures, escarpments, and graben that have resulted from the tectonic
deformation that is pervasive throughout the region.  These structures
range in width from approximately 2 kilometers (1.2 miles) down to the
limits of Magellan resolution (approximately 250 meters [825 feet]).  Three
large, shallow graben near the top of the image appear to have very smooth
floors, and may be partially flooded by the same volcanic materials that
are thought to have formed most of the plains.  The dark region in the left
central portion of the image is probably a region of very smooth plains,
possibly a result of relatively recent volcanism.  It is clearly postdated
by tectonic deformation, particularly by the set of structures trending ENE
and NW.  The broader, diffusely bright regions adjacent to the graben may
be due to mass-wasting and aeolian transport of materials from the steep
scarps.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37130
                                        11/20/90

This image is centered at approximately 29.6 degrees south latitude and 341
degrees east longitude in the Lavinia Region of Venus.  Volcanic vent areas
in this part of the plains west of Alpha Regio consist of domes and pits up
to nearly 3 kilometers across.  Extending eastward these features are
sinuous channels, most of which are about 10 kilometers or more long.  The
channels narrow away from the pits and for most of their lengths are about
1 kilometer in diameter.  The nearest planetary analogues for these
features are sinuous rilles on the moon.  These have been explained as lava
channels and/or the result of lava erosion.  On Earth lava channels form by
downhill drainage of a lava flow leaving a channel behind.  Lava may
continue to flow in the channel once it has formed.  However, lava channels
on Earth are normally only a few meters or tens of meters wide.  On the
other hand, they may be the result of lava erosion.  This is a process that
only normally occurs to a limited extent on Earth because melting is
inhibited by the cool upper layers of the planet.  Also, lavas rarely flow
turbulently enough to cause mechanical erosion.  On Venus the surface
materials are already at high temperatures, thus assisting thermal erosion
and it is possible that lavas which may flow turbulently are more readily
available than on earth.  Resolution of the Magellan data is about 120
meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37131
                                        11/20/90

This SAR image from the southern portion of Navka (24.4-25.3 degrees south
latitude, 338.5-340.5 degrees east longitude) is a mosaic of twelve
Magellan orbits that covers 180 kilometers (108 miles) in width and 78
kilometers (47 miles) in length.  In the center of this image are two
bright deposits running north to south.  These deposits outline an outflow
channel that flowed from a 60-km diameter crater that is to the south of
the channel.  Inside the outflow channel and outlined by "bathtub ring"
deposits are small cones, most likely of volcanic origin.  At the end of
the outflow channel, where one would expect the smallest particles to be
deposited, are specular features which may represent sand dunes.  Seasat
and space shuttle radar images of sand dunes on Earth also show specular
reflections from smooth dune faces that are near-normal to the radar beam.
Other evidence for aeolian activity are the dark and bright windstreaks
running east to west that form behind cones.  Notice how the wind changes
direction from a southeast-northwest flow at the right of the image to an
east-west flow at the eastern edge of the outflow channel.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37132
                                        11/20/90

In addition to radar images of the surface, the Magellan spacecraft uses a
variety of methods to study Venus and its geology.  These four images of
the same area show an unnamed impact crater 31 kilometers (19 miles) across
in the fractured plains of Guinevere Planitia.  The images are 540 by 640
kilometers (324 by 384 miles) across.  These images were acquired on orbits
376 to 399 on September 15-18, 1990.  They extend from 15 degrees to 25
degrees north latitude and from 315 degrees to 349 degrees east longitude.
The Synthetic Aperture Radar image (upper left) shows that the crater, with
its bright petal-like ejecta deposit is surrounded by a broad diffuse dark
region several hundred kilometers across which is seen in other images to
extend further west.  This dark region is also prominent in the image at
lower left which is a Reflectivity image (a measure of the strength of the
radar return signal that is bounced off the surface) and shows up as a
bright, highly reflective region.  The radar system can also measure the
RMS slope, or roughness of the surface as seen by the radar signal (image
at lower right).  This dark region in the radar image is also dark in the
slope image, indicating it is relatively smooth.  Scientists speculate that
this dark region may be the result of a fine ash fallout caused by the
impact explosion in the Venusian atmosphere.  The volcanic fields visible
at the right-hand side of the SAR image is also visible in the slope image
as a rough area and is elevated (bright) in the Topography image at upper
right, where brightness indicates elevation.  The impact crater in the SAR
image is also noticeable in the topo image as a shallow depression several
hundred meters deep.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37135
                                        11/20/90

This is a Magellan radar image mosaic of the Lavinia region of Venus.  The
mosaic consists of parts of orbits 376 through 416 acquired between
September 15 and September 21, 1990.  The center of the image is located at
40 degrees south latitude, 342.5 degrees east longitude and is about 615
kilometers (382 miles) wide and 538 kilometers (334 miles) long.  The
region shown includes a variety of different terrain types indicating a
complex geological history.  In the northern half of the image are dark
mottled plains, interpreted as widespread lava flows subsequently modified
by sub-parallel ridges.  These are similar to the "wrinkle ridges" found on
the lunar mare.  To the north-west there is a cluster of volcanic edifices,
the larger of which are approximately 3.5 kilometers (2.2 miles) in
diameter.  Some of these possess distinct summit pits and they are
interpreted as lava shields.  On the southern margin of the image are radar
dark lava plains which also have small volcanic structures on them.
Running across the southern half of the image is a large ridge belt which
rises about 1 kilometer (0.6 mile) above the surrounding plains.  This is
interpreted to be a zone of compression and crustal thickening.  In places
it has been partially flooded by radar dark lavas.  The relief of the
individual ridges is estimated to be about 100 meters (330 ft).  In places
they are seen to be grouped into `bands' approximately 20 kilometers (12.4
miles) wide.  The size of these bands gives a measure of the scale of
deformation of the brittle upper part of the planet's crust which in turn
indicates its thickness.  This thickness has been calculated as
approximately 4 kilometers (2.5 miles).  Finally, half way down the image,
towards the eastern edge, an impact crater can be seen.  This crater has a
diameter of about 7 kilometers (4.3 miles).  Of particular note is the
asymmetry of the bright ejecta material which surrounds the crater.  This
is one of the youngest features visible in the image.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37137  MGN-19
                                        11/16/90

This Magellan image reveals Sacajawea Patera, a large, elongate caldera
located in Western Ishtar Terra on the smooth plateau of Lakshmi Planum.
The image is centered at 64.5 degrees North latitude and 337 degrees East
longitude.  It is approximately 420 kilometers (252 miles) wide at the
base.  Sacajawea is a depression approximately 1-2 kilometers (0.6-1.2
miles) deep and 120 x 215 kilometers (74 x 133 miles) in diameter; it is
elongate in a southwest-northeast direction.  The depression is bounded by
a zone of circumferential curvilinear structures interpreted to be graben
and fault scarps.  These structures are spaced 0.5-4 kilometers (0.3-2.5
miles) apart, are 0.6-4.0 kilometers (0.4-2.5 miles) in width and up to 100
kilometers (62 miles) in length.  Extending up to approximately 140
kilometers (87 miles) in length from the southeast of the patera is a
system of linear structures thought to represent a flanking rift zone along
which the lateral injection and eruption of magma may have occurred.  A
shield edifice 12 kilometers (7 miles) in diameter with a prominent central
pit lies along the trend of one of these features.  The impact crater Zlata
, approximately 6 kilometers (4 miles) in diameter is located within the
zone of graben to the northwest of the patera.  Few flow features are
observed in association with Sacajawea, possibly due to age and state of
degradation of the flows.  Mottled bright deposits 4-20 kilometers (2.5-12
miles) in width are located near the periphery and in the center of the
patera floor within local topographic lows.  Diffuse patches of dark
material approximately 40 kilometers (25 miles) in width are observed
southwest of the patera, superposed on portions of the surrounding graben.
The formation of Sacajawea is thought to be related to the drainage and
collapse of a large magma chamber.  Gravitational relaxation may have
caused the resultant caldera to sag, producing the numerous faults and
graben that circumscribe the patera.  Regions of complex, highly deformed
tessera-like terrain are located north and east of the patera and are seen
in the upper portion of the image.  Color has been added to this image to
simulate the appearance of the Venus surface.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37138  MGN-20
                                        11/16/90

This image shows a 125 by 125 km region on the eastern flanks of Freyja
Montes, in Ishtar Terra, centered on 72 degrees north, 342 degrees east.
The image is dominated by a highly fractured dome, approximately 70 by 125
km (42 by 75 miles), that appears to delineate a local region of uplift and
extension within the regionally compressional mountain belt.  The "turtle-
back" appearance of the dome is the result of two sets of intersecting
fractures; one trending roughly north to north northeast and the other west
to west northwest.  Individual scarps appear to define graben, commonly 1
by 5 km (0.6 by 3.0 miles) wide.  Age relationships between the two sets of
graben are complex, but west northwest trending features most often appear
to crosscut the north trending graben.  In the eastern portion of the
image, structures have been heavily embayed by volcanic plains deposits.
The appearance of a purely extensional feature within the compressional
zone of the Freyja Montes orogenic belt may have significant implications
for the mechanisms by which mountains are built on Venus.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37139  MGN-21
                                        11/16/90

This image is a full-resolution mosaic of several Magellan images and is
centered at 61 degrees north latitude and 341 degrees east longitude.  The
image is 250 kilometers wide (150 miles).  The radar smooth region in the
northern part of the image is Lakshmi Planum, a high plateau region roughly
3.5 kilometers (2.2 miles) above the mean planetary radius.  Lakshmi Planum
is ringed by intensely deformed terrain, some of which is shown in the
southern portion of the image and is called Clotho Tessera.  The 64-
kilometer (40 mile) diameter circular feature in the image is a depression
called Siddons and may be a volcanic caldera.  This view is supported by
the collapsed lava tubes surrounding the feature.  By carefully studying
this and other surrounding images scientists hope to discover what tectonic
and volcanic processes formed this complex region.  The solid black parts
of the image represent data gaps that may be filled in by the Magellan
extended mission.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37140  MGN-22
                                        11/16/90

This image is a mosaic of Magellan data over the Lakshmi region of Venus.
The image is centered at about 66 degrees north latitude and 10 degrees
east longitude.  The prominent circular feature in the image is the crater
Cleopatra located on the eastern slopes of Maxwell Montes, the highest
mountain range on Venus.  Cleopatra is about 100 km (60 miles) across and
2.5 km (1.5 miles) deep.  In previous data sets, scientists were unable to
determine whether Cleopatra was an impact crater or a volcanic caldera.
High-resolution Magellan data indicates that Cleopatra is a double-ring
impact basin, similar to double-ring impact basins identified on the Moon,
Mars and Mercury.  The inner and outer rings have a hummocky appearance
typical of very large impact craters.  On the eastern edge of Cleopatra, a
flow can be seen that has breached the wall of the crater and flowed
downhill to surround the ridges to the east.  This flow may have been
produced by melting of rocks due to the impact or by volcanism triggered by
the impact.  Resolution of the Magellan data is about 120 meters (400
feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37141  MGN-23
                                        11/16/90

This Magellan full resolution radar image is centered at 65 degrees north
latitude, zero degrees east longitude, along the eastern edge of Lakshmi
Planum and the western edge of Maxwell Montes.  The plains of Lakshmi are
made up of radar-dark, homogeneous, smooth lava flows.  Located near the
center of the image is a feature previously mapped as tessera made up of
intersecting 1 to 2 km (0.6 to 1.2 miles) wide graben.  The abrupt
termination of dark plains against this feature indicates that it has been
partially covered by lava.  Additional blocks of tessera are located along
the left hand edge of the image.  A series of linear parallel troughs are
located along the southern edge of the image.  These features, 60 to 120 km
(36 to 72 miles) long and 10 to 40 km (6 to 24 miles) wide are interpreted
as graben.  Located along the right hand part of the image is Maxwell
Montes, the highest mountain on the planet, rising to an elevation of 11.5
km (7 miles) and is part of a series of mountain belts surrounding Lakshmi
Planum.  The western edge of Maxwell shown in this image rises sharply, 5.0
km (3.0 miles), above the adjacent plains in Lakshmi Planum.  Maxwell is
made up of parallel ridges 2 to 7 km (1.2 to 4.2 miles) apart and is
interpreted to have formed by compressional tectonics.  The image is 300
kilometers (180 miles) wide.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37236  MGN-25
                                        12/03/90

This image shows a flooded impact crater, several collapse features, and
lava flows to the south of Lavinia Planitia in the southern hemisphere.
Centered at 60 degrees south latitude, 352 degrees east longitude, the
image covers an area of approximately 300 x 500 kilometers (180 x 300
miles).  The impact crater is 65 kilometers (39 miles) in diameter and was
originally about 500 meters (1300 feet) deep but has been almost completely
buried by lava flows, leaving only the rim and the southeastern part of the
bright, rough ejecta deposit.  Recent lava flows appear as bright or dark
regions with sinuous boundaries.  Collapse features are linear or sinuous
valleys which range from 200 meters (650 feet) to 5 kilometers (3 miles) in
width and are up to 100 kilometers (60 miles) long.  These valleys may form
when subsurface magma drains along tectonic fractures, allowing the
overlying surface to collapse.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37264
                                        12/5/90

This Magellan image covers a region 77 kilometers (46 miles) wide and 85
kilometers (51 miles) high.  This image shows part of a long, open channel
at 76.5 degrees north latitude, 335 degrees longitude in the Vires-akka
Chasma, about 100 kilometers (60 miles) north of Freyja Montes, in the
Denitsa Region of Venus.  The channel ranges in width from less than 1
kilometer (3300 feet) to 4 kilometers (2.4 miles).  The portion of the
channel visible in this scene is over 120 kilometers (72 miles) long.
Longitudinal scour features are visible within the channel, particularly
where it makes abrupt turns.  The channel may have been carved by very low
viscosity lavas that were able to remain fluid over great distances and
thermally erode pre-existing terrain due to the extreme temperatures at
Venus' surface.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37265
                                        12/5/90

This Magellan image is centered at 25 degrees south latitude, 345 degrees
longitude, in northern Lavinia Region of Venus.  The image, which is 500
kilometers (300 miles) in length and width, is a mosaic of orbits 401-437.
A large impact crater with a diameter of about 40 kilometers (24 miles) has
two associated lava flows at the crater's southern rim.  The lava flows may
have formed right after the impact.  The bright radar return indicates that
the flows are very rough on the scale of the radar wavelength (12
centimeters).  Surrounding the crater is a dark parabolic feature that may
be debris associated with the impact.  The abundance of windstreaks in the
image indicates that there is sediment in this area transportable by the
surface winds.  The windstreaks on the dark parabolic feature indicate that
the wind is blowing from the southwest to the northeast at the bottom of
the image and is deflected to a southeast-northwest flow around the crater.
The majority of the windstreaks in this flow regime are radar bright
streaks overlying radar dark streaks.  To the southwest of the crater, some
thin dark windstreaks flow through a ridge belt (bright linear features),
apparently following the topography.  At the upper left of the image is a
long sinuous channel.  The channel may have formed by drainage of lava to
the south or it may be the result of lava erosion.  Resolution of the
Magellan data is about 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37265  MGN-27
                                        1/25/91

This Magellan image is centered at 25 degrees south latitude, 345 degrees
longitude, in northern Lavinia Region of Venus.  The image, which is 500
kilometers (300 miles) in length and width, is a mosaic of orbits 401-437.
A large impact crater with a diameter of about 40 kilometers (24 miles) has
two associated lava flows at the crater's southern rim.  The lava flows may
have formed right after the impact.  The bright radar return indicates that
the flows are very rough on the scale of the radar wavelength (12
centimeters).  Surrounding the crater is a dark parabolic feature that may
be debris associated with the impact.  The abundance of windstreaks in the
image indicates that there is sediment in this area transportable by the
surface winds.  The windstreaks on the dark parabolic feature indicate that
the wind is blowing from the southwest to the northeast at the bottom of
the image and is deflected to a southeast-northwest flow around the crater.
The majority of the windstreaks in this flow regime are radar bright
streaks overlying radar dark streaks.  To the southwest of the crater, some
thin dark windstreaks flow through a ridge belt (bright linear features),
apparently following the topography.  At the upper left of the image is a
long sinuous channel.  The channel may have formed by drainage of lava to
the south or it may be the result of lava erosion.  Resolution of the
Magellan data is about 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37266
                                        12/5/90

This image is a mosaic of Magellan orbits 385-399.  It covers a region 370
kilometers (220 miles) wide and 455 kilometers (270 miles) high, centered
at about 30 degrees north latitude, 335 south longitude, in southeast
Guinevere Planitia in the Navka Region of Venus.  Trending from lower right
toward upper left of the image is a long, sinuous, radar-dark rille-like
feature.  This rille is about 500 kilometers (300 miles) long in this
image, and it has been traced for approximately an additional 500
kilometers to the east where its source may lie buried beneath younger
plains volcanics.  The rille maintains a nearly constant width of between
750 meters (230 feet) and 2 kilometers (1.2 miles) throughout its length.
It appears to terminate in the broad, radar-dark V-shaped plains unit at
the upper left.  The margins of the rille are bright in the radar,
suggesting levees similar to terrestrial lava channel levees.  In addition,
a number of faint, apparently abandoned rilles branch off the main rille,
suggesting that flow was maintained for a relatively long time.  Its great
dimensions and implied longevity are likely due to the ability of lava in
Venus' high temperature environment to remain fluid and thermally erode
terrain over great distances when compared to terrestrial lava flows.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37296
                                        12/14/90

Dark Halos Revealed Around Impact Craters: New Geologic Clocks for Venus?

This Magellan image mosaic located in the Lavinia region shows the crater
Carson, a 38 km (23 mile) diameter crater.  The image is centered at about
24 degrees south latitude, 344 degrees longitude.  Impact craters in the
Magellan data are frequently surrounded by radar-dark halos.  Several of
these halos were noted to have a hyperbolic shape, extending hundreds of
kilometers to the west of the craters.  Five of these dark halos were also
seen extending out from craters in Magellan emissivity data.  Magellan
emissivity data, derived from the altimeter data, provides information
about the porosity (soil versus solid rock) and the composition of the
surface.  The darkness in the emissivity data indicates a very smooth
surface, leading to the interpretation that these halos may be thick,
smooth sediment deposits formed by the 'crushing' blow of the atmosphere
associated with the incoming projectile that formed the impact crater.  But
why are only about 5% of the craters surrounded by these halos?  On the
surface of most planets, the population of impact craters can be used to
obtain both relative and absolute surface ages.  On Venus, as on Earth,
there are relatively few craters, making relative age dating (comparing one
region of the planet to another) statistically difficult.  The number of
craters on Venus indicates that the surface may be only about 400 million
years old.  The dark halos may indicate the very youngest craters on the
planet - where the harsh conditions on Venus have not yet caused these dark
halos to 'roughen up' and disappear.  The halos could possibly be used as
'geologic clocks.'  Volcanic flows or tectonic structures cutting one of
these halos are interpreted to have occurred even more recently than the
craters.  This image shows such a situation, where flows associated with
the crater cut across the halo, indicating a very young age.  Scientists
are continuing to identify these halos in the Magellan data, and use them
to understand the geologic evolution of the surface.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37322
                                        1/11/91

This mosaic of a portion of Alpha Regio in the Lavinia region of Venus is
centered around 24.2 degrees south latitude and 1.7 degrees east longitude
and covers an area about 170 kilometers (106.3 miles) by 210 kilometers
(131.3 miles).  The terrain shows intense folding, faulting, shearing,
compression and extension.  The complex pattern of intersecting ridges and
valleys is called "tessera."  Here, the terrain shows relatively long (50-
kilometer or 30-mile) zones that intersect shorter ridges and valleys at
approximately right angles.  It appears that the region has undergone many
episodes of horizontal motion.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37342
                                        12/21/90

This false-color view of the volcano Sif Mons was made by superposing
Magellan radar image data on altimetry data.  The volcano is 2.0 kilometers
(1.2 mile) high and 300 kilometers (180 miles) in diameter.  Sif Mons is
located on the broad 2300 kilometers x 2000 kilometers (1380 x 1200 miles)
rise of Western Eistla Regio, a region that may have formed from the
upwelling of hot material from the interior of the planet.  The view of the
mountain is from the northeast to the southwest and shows an area just
below the summit of the peak.  A series of bright and dark lava flows are
present in the central part of the image.  The brightest flows, which are
relatively rough or blocky, are associated with the most recent volcanism
on this part of the volcano and are superposed on darker, smoother, and
older flows.  The bright flows extend for a distance of 120 kilometers (72
miles) down the flank of the mountain.  The long length of the flows
indicates that the lavas were extremely fluid at the time that they were
erupted onto the surface.  The superposition of the image and topography
data facilitates in identifying regions where lava flows are controlled by
local changes in topography, and thus allows scientists to understand
better the volcanic processes that formed the volcano and make detailed
comparisons to volcanoes on Earth.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37342  MGN-28
                                        1/25/91

This false-color view of the volcano Sif Mons was made by superposing
Magellan radar image data on altimetry data.  The volcano is 2.0 kilometers
(1.2 mile) high and 300 kilometers (180 miles) in diameter.  Sif Mons is
located on the broad 2300 kilometers x 2000 kilometers (1380 x 1200 miles)
rise of Western Eistla Regio, a region that may have formed from the
upwelling of hot material from the interior of the planet.  The view of the
mountain is from the northeast to the southwest and shows an area just
below the summit of the peak.  A series of bright and dark lava flows are
present in the central part of the image.  The brightest flows, which are
relatively rough or blocky, are associated with the most recent volcanism
on this part of the volcano and are superposed on darker, smoother, and
older flows.  The bright flows extend for a distance of 120 kilometers (72
miles) down the flank of the mountain.  The long length of the flows
indicates that the lavas were extremely fluid at the time that they were
erupted onto the surface.  The superposition of the image and topography
data facilitates in identifying regions where lava flows are controlled by
local changes in topography, and thus allows scientists to understand
better the volcanic processes that formed the volcano and make detailed
comparisons to volcanoes on Earth.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37375
                                        1/4/91

One of the most useful Magellan standard data products is the full
resolution mosaic, the F-MIDR (Full-Resolution Mosaicked Image Data
Record).  These products are mosaics of about 500 kilometer (300 mile)
segments of 30 or more individual image strips.  This image is an F-MIDR
made from orbits 376 to 407, obtained between September 15 and September
19, 1990, part of the first orbits in which the Magellan flight team
operated the radar system in the mapping mode.  The mosaic is centered at
27 degrees south latitude, 339 degrees longitude, in the Lavinia region of
Venus.  Three large impact craters with diameters ranging from 37
kilometers (23 miles) to 50 kilometers (30 miles) can be seen located in a
region of fractured plains.  The craters show many features typical of
meteorite impact craters, including rough, radar-bright ejecta, terraced
inner walls and central peaks.  Numerous domes of probable volcanic origin
can be seen in the southeastern corner of the mosaic.  The domes range in
diameter from 1-12 kilometers (0.6-7 miles), and some have central pits
typical of volcanic shields or cones.  Resolution of the Magellan data is
about 120 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37431
                                        1/3/91

Perspective view of the southern boundary of Lakshmi Planum,
Ishtar Terra, Venus.

The southern scarp and basin province of western Ishtar Terra in the
northern hemisphere of Venus is portrayed in this three-dimensional
perspective view of Magellan radar image data.  Western Ishtar Terra is an
Australia-sized highland terrain that is a major focus of Magellan
investigations.  The highland is centered on a 2.5 to 4 kilometer-high (1.5
to 2.5 miles-high) plateau, Lakshmi Planum, which can be seen in the
distance and to the right.  Along this part of the Planum, the surface of
the high plateau drops precipitously into the bounding lowlands, with
slopes that exceed 5 percent over 50 kilometers (30 miles).  The numerous
fractures and valleys located on and adjacent to the steep outer slope of
the plateau are clues to the formation of this unusually abrupt topographic
drop.  Along other parts of the boundary of Lakshmi are mountain ranges
that rise as much as 6 kilometers (3.5 miles) above the plateau surface to
over 11,000 meters (35,000 feet) above the mean elevation of the surface of
Venus.  One of these mountain ranges, Danu Montes, rises over 1.5
kilometers (1.0 mile) above the plateau and can be seen in the upper center
of the image.

Images such as this one show the relationship of geological features to
topography and yield a valuable new perception of the radar data.  For
example, the small dome-shaped high (center left) is a volcano that is not
apparent in the normal map-view display of Magellan images.  Only when
combined with topography in this fashion is the nature of the feature
clearly evident.  These perspective views also display fractures of the
surface in their actual topographic setting.  Understanding the
relationship of topography to these fractures, which express the stresses
and motions in the outer layers of the planet, helps geologists and
geophysicists to formulate and test models for the formation of western
Ishtar.  The results of these studies will add to our understanding of the
interior forces that shape the surface of Venus.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37431  MGN-29
                                        1/25/91

Perspective view of the southern boundary of Lakshmi Planum, Ishtar Terra,
Venus.

The southern scarp and basin province of western Ishtar Terra in the
northern hemisphere of Venus is portrayed in this three-dimensional
perspective view of Magellan radar image data.  Western Ishtar Terra is an
Australia-sized highland terrain that is a major focus of Magellan
investigations.  The highland is centered on a 2.5 to 4 kilometer-high (1.5
to 2.5 miles-high) plateau, Lakshmi Planum, which can be seen in the
distance and to the right.  Along this part of the Planum, the surface of
the high plateau drops precipitously into the bounding lowlands, with
slopes that exceed 5 percent over 50 kilometers (30 miles).  The numerous
fractures and valleys located on and adjacent to the steep outer slope of
the plateau are clues to the formation of this unusually abrupt topographic
drop.  Along other parts of the boundary of Lakshmi are mountain ranges
that rise as much as 6 kilometers (3.5 miles) above the plateau surface to
over 11,000 meters (35,000 feet) above the mean elevation of the surface of
Venus.  One of these mountain ranges, Danu Montes, rises over 1.5
kilometers (1.0 mile) above the plateau and can be seen in the upper center
of the image.

Images such as this one show the relationship of geological features to
topography and yield a valuable new perception of the radar data.  For
example, the small dome-shaped high (center left) is a volcano that is not
apparent in the normal map-view display of Magellan images.  Only when
combined with topography in this fashion is the nature of the feature
clearly evident.  These perspective views also display fractures of the
surface in their actual topographic setting.  Understanding the
relationship of topography to these fractures, which express the stresses
and motions in the outer layers of the planet, helps geologists and
geophysicists to formulate and test models for the formation of western
Ishtar.  The results of these studies will add to our understanding of the
interior forces that shape the surface of Venus.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37484
                                        1/11/91

This image is located west of Alpha Regio at 26.5 south latitude, 340 east
longitude.  The image was processed using split-spectrum color processing
to enhance details.  The image shows an impact crater in the lower right
with a channel feature extending from its ejecta in the north.  The east-
west trending streaks across the top of the image are believed to be formed
by wind redistribution of fine dust and sand particles.  The sharper
details in the image are shown by varying the intensity of the color and
the broad slowly varying radar reflectivity is depicted by varying the hue.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37492
                                        1/14/91

Chaotic Tessera Terrain at Alpha Regio

This chaotic terrain is located within central Alpha Regio and is called
"tessera."  Tessera is the Greek word for "tile" and was first used by the
Soviets as a morphometric term to describe complicated terrains in Venera
15/16 radar imagery.  This area lies between 25.0 and 26.5 degrees south
latitude and between 359.9 and 1.4 degrees east longitude.  This
complicated type of terrain is often found at relatively high elevations up
to 3 kilometers (9900 feet) above the surrounding plains.  The largest
structures are arcuate ridges and troughs that are about 10 kilometers (6.3
miles) wide and less than 70 kilometers (43.8 miles) long.  The presence of
multiple linear and curvilinear structures at various scales probably
indicates that this area has undergone many episodes of deformation.
Narrow graben, trending NW-SE, are ubiquitous in this area and cross-cut
virtually all the other structures.  Thus, these graben appear to represent
the latest phase of deformation in the area.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37493
                                        1/14/91

West-central edge of tessera at Alpha Regio

The western edge of tessera terrain located at central Alpha Regio is shown
in this figure.  This area lies between 23.8 and 25.0 degrees south
latitude and between 356.7 and 357.9 degrees east longitude.  The north-
south trending radar-bright and dark lineaments correspond to structures
within broad topographic ridges and troughs that are also oriented north-
south.  The spacing of the broad ridges and troughs is about 10-20
kilometers (6.3-12.5 miles).  The ridges and troughs are located within a
local topographic low and are clearly embayed by smooth volcanic plains to
the west.  In general, the elevation increases toward the east.  The
existence of relatively undeformed plains at various levels upslope clearly
indicates that volcanism postdates the latest structural deformation in
this part of the tessera.  East of this area, in central Alpha, the tessera
terrain rises up to 3 kilometers (9900 feet) above the surrounding plains
and is often intensely deformed.  Tessera is the Greek word for "tile" and
was first used by the Soviets as a morphometric term to describe
complicated terrains in Venera 15/16 radar imagery.
                          MAGELLAN PROJECT OFFICE

                                  P-37500
                                  1/21/91

This is a Magellan radar image mosaic of Venus centered on 30 degrees
south, 9 degrees east.  This scene is approximately 600 kilometers (360
miles) across and includes data from orbits 522 through 561, acquired on
October 5-10, 1990.  The bright terrain unit is the southeastern portion of
Alpha Regio, a mountainous, highly fractured region.  The complex fracture
and deformation history of Alpha Regio is responsible for the intricate
pattern of ridges and valleys.  To the south and east these highlands have
been flooded and embayed by dark, smooth plains material which apparently
formed by extensive eruptions of basalt-like lavas.  Several lava flow
channels are visible at bottom center.  Volcanically embayed remnants of
Alpha Regio can be seen as isolated patches.  Within these dark plains
occur eight rounded "pancake" domes up to 35 kilometers (20 miles) across
and up to 1 kilometer (0.6 miles) high clustered at right center and at
bottom right.  Several of these domes have fractured and pitted summits.
The shapes of these broad flat domes suggests they formed from the
extrusion of lavas considerably more viscous (sticky) than those that
formed the dark plains.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37501
                                  1/21/91

Arachnoids, one of the more remarkable features found on Venus, are seen on
radar-dark plains in this Magellan image mosaic in the Fortuna region.  The
image is centered at about 40 degrees north latitude, 18 degrees longitude.
As the name suggests, arachnoids are circular to ovoid features with
concentric rings and a complex network of fractures extending outward.  In
this image, the arachnoids range in size from approximately 50 kilometers
(29.9 miles) to 230 kilometers (137.7 miles) in diameter.  Since arachnoids
are similar in form but generally smaller than coronae (circular volcanic
structures surrounded by a set of ridges and grooves as well as radial
lines), one theory concerning their origin is that they are a precursor to
coronae formation.  The radar-bright lines extending for many kilometers
may have been caused by an upwelling of magma from the interior of the
planet which pushed up the surface to form "cracks."  Radar-bright lava
flows are present in the central part of this image, also indicative of
volcanic activity in this area.  Some of the fractures cut across these
flows, indicating that the flows occurred before the fractures appeared;
such relations between different structures provides good relative age
dating of events.  At present, arachnoids are found only on Venus and can
now be more closely studied with the high resolution (120 meter/0.07 mile)
radar imagery from Magellan.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37501  MGN-30
                                        1/25/91

Arachnoids, one of the more remarkable features found on Venus, are seen on
radar-dark plains in this Magellan image mosaic in the Fortuna region.  The
image is centered at about 40 degrees north latitude, 18 degrees longitude.
As the name suggests, arachnoids are circular to ovoid features with
concentric rings and a complex network of fractures extending outward.  In
this image, the arachnoids range in size from approximately 50 kilometers
(29.9 miles) to 230 kilometers (137.7 miles) in diameter.  Since arachnoids
are similar in form but generally smaller than coronae (circular volcanic
structures surrounded by a set of ridges and grooves as well as radial
lines), one theory concerning their origin is that they are a precursor to
coronae formation.  The radar-bright lines extending for many kilometers
may have been caused by an upwelling of magma from the interior of the
planet which pushed up the surface to form "cracks."  Radar-bright lava
flows are present in the central part of this image, also indicative of
volcanic activity in this area.  Some of the fractures cut across these
flows, indicating that the flows occurred before the fractures appeared;
such relations between different structures provides good relative age
dating of events.  At present, arachnoids are found only on Venus and can
now be more closely studied with the high resolution (120 meter/0.07 mile)
radar imagery from Magellan.
                          MAGELLAN PROJECT OFFICE

                                  P-37554
                                  1/28/91

This full-resolution mosaicked image illustrates how the relative age of
features can be determined from cross-cutting relationships.  The image is
part of the Fortuna region of Venus and is centered at 60 degrees north
latitude and 16 degrees east longitude.  The image includes an area 620
kilometers (382 miles) wide and 550 kilometers (339 miles) from north to
south.  This image of southwestern Fortuna tessera displays the complex
deformation typical of tessera.  The oldest structures are relatively
short, broad ridges and valleys which generally trend north-northeast.
These structures are cut by long north-south to northwest-trending dark and
bright lines that appear throughout the image.  These are interpreted to be
extensional faults, and commonly are paired and form graben (down-dropped,
flat-floored valleys) and horsts (upthrown ridges).  In the western half of
the image, younger lava flows fill valleys formed by both of the older sets
of structures.  These flows are dark in the image because they are smooth.
The bright feature in the northwest corner of the image is the southeastern
corner of Maxwell Montes.  This area is unusually radar-bright due to
composition of the surface materials.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37598
                                  2/5/91

This image is a mosaic of Magellan orbits 376-402.  It is centered at 5
degrees south latitude, 335 degrees east longitude, in the Navka region of
Venus.  The image is dominated by a broad plains region with scattered
small volcanic constructs and extensional graben or troughs.

The radar-bright and dark patches are volcanic flows overlying, or in some
cases partially buried by other plains materials.  Many of these flow units
contain small volcanic domes.  The reason for such a wide range of radar
brightness variations in these flow units is probably due to differences in
surface roughness and/or compositional differences.

The vertical striping in this mosaic (the so-called "venetian blind
effect") was caused by a two-thirds of a second mismatch between where the
radar data processing system assumed the radar antenna pattern was hitting
the ground and where the radar was actually illuminating the surface.  This
small error was enough to cause the radar processing system to improperly
process data for those orbits, resulting in the banding seen here.  This
timing error appears only in early orbits which were acquired before the
radar instrument's behavior was fully understood.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37598  MGN-31
                                        2/22/91

This image is a mosaic of Magellan orbits 376-402.  It is centered at 5
degrees south latitude, 335 degrees east longitude, in the Navka region of
Venus.  The image is dominated by a broad plains region with scattered
small volcanic constructs and extensional graben or troughs.

The radar-bright and dark patches are volcanic flows overlying, or in some
cases partially buried by other plains materials.  Many of these flow units
contain small volcanic domes.  The reason for such a wide range of radar
brightness variations in these flow units is probably due to differences in
surface roughness and/or compositional differences.

The vertical striping in this mosaic (the so-called "venetian blind
effect") was caused by a two-thirds of a second mismatch between where the
radar data processing system assumed the radar antenna pattern was hitting
the ground and where the radar was actually illuminating the surface.  This
small error was enough to cause the radar processing system to improperly
process data for those orbits, resulting in the banding seen here.  This
timing error appears only in early orbits which were acquired before the
radar instrument's behavior was fully understood.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37599
                                  2/12/91

This full-resolution radar image mosaic of part of Venus is centered on 75
degrees north latitude, 332 degrees east longitude.  Parts of orbits 376
through 444 are included in this area, which is 310 kilometers (190 miles)
wide and 550 kilometers (339 miles)north to south.  The radar-bright
mountains, called Freyja Montes, are probably formed mostly as a result of
compressional folding and faulting of rock units.  The smooth, dark plains
to the south are the northernmost extent of Lakshmi Planum, a region
believed covered by extensive volcanism, although several compressional
fault ridges can be seen extending southward from Freyja Montes.  A sinuous
lava channel is seen running along the floors of some of the valleys
between the mountains belts at the top of the image, indicating that these
valleys are partially flooded by lavas.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37599  MGN-32
                                        2/22/91

This full-resolution radar image mosaic of part of Venus is centered on 75
degrees north latitude, 332 degrees east longitude.  Parts of orbits 376
through 444 are included in this area, which is 310 kilometers (190 miles)
wide and 550 kilometers (339 miles)north to south.  The radar-bright
mountains, called Freyja Montes, are probably formed mostly as a result of
compressional folding and faulting of rock units.  The smooth, dark plains
to the south are the northernmost extent of Lakshmi Planum, a region
believed covered by extensive volcanism, although several compressional
fault ridges can be seen extending southward from Freyja Montes.  A sinuous
lava channel is seen running along the floors of some of the valleys
between the mountains belts at the top of the image, indicating that these
valleys are partially flooded by lavas.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
(ALSO P-37600)
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
(ALSO P-37600)                          P-37135
                                        11/20/90

This is a Magellan radar image mosaic of the Lavinia region of Venus.  The
mosaic consists of parts of orbits 376 through 416 acquired between
September 15 and September 21, 1990.  The center of the image is located at
40 degrees south latitude, 342.5 degrees east longitude and is about 615
kilometers (382 miles) wide and 538 kilometers (334 miles) long.  The
region shown includes a variety of different terrain types indicating a
complex geological history.  In the northern half of the image are dark
mottled plains, interpreted as widespread lava flows subsequently modified
by sub-parallel ridges.  These are similar to the "wrinkle ridges" found on
the lunar mare.  To the north-west there is a cluster of volcanic edifices,
the larger of which are approximately 3.5 kilometers (2.2 miles) in
diameter.  Some of these possess distinct summit pits and they are
interpreted as lava shields.  On the southern margin of the image are radar
dark lava plains which also have small volcanic structures on them.
Running across the southern half of the image is a large ridge belt which
rises about 1 kilometer (0.6 mile) above the surrounding plains.  This is
interpreted to be a zone of compression and crustal thickening.  In places
it has been partially flooded by radar dark lavas.  The relief of the
individual ridges is estimated to be about 100 meters (330 ft).  In places
they are seen to be grouped into `bands' approximately 20 kilometers (12.4
miles) wide.  The size of these bands gives a measure of the scale of
deformation of the brittle upper part of the planet's crust which in turn
indicates its thickness.  This thickness has been calculated as
approximately 4 kilometers (2.5 miles).  Finally, half way down the image,
towards the eastern edge, an impact crater can be seen.  This crater has a
diameter of about 7 kilometers (4.3 miles).  Of particular note is the
asymmetry of the bright ejecta material which surrounds the crater.  This
is one of the youngest features visible in the image.
                          MAGELLAN PROJECT OFFICE

                                  P-37601
                                  2/19/91

This is a Magellan full-resolution radar mosaic of the Lavinia region of
Venus.  The mosaic is centered at 50 degrees south latitude, 345 degrees
east longitude, and spans 540 kilometers (338 miles) north to south and 900
kilometers (563 miles) east to west.  As with all Magellan images acquired
thus far, the illumination of the radar is from the left-hand side of the
image.  This area shows a diverse set of geologic features.  The bright
area running from the upper right to the lower left is interpreted as part
of a belt of ridges, formed by compression and thickening of the upper
layers of the planet.  The areas between ridges suggest flooding by radar
dark (and thus presumably) smoother lavas.  The varied textures of the
lavas can be seen in the mottled appearance of the plains which are cut by
the ridges; brighter, rougher flows are also quite common.  The
particularly bright flows in the lower right corner are the northern
extension of Mylitta Fluctus.  The bright ridges adjacent to Mylitta
Fluctus at the bottom center of the image also appear to have been affected
by the volcanic activity.  Some of these bright features have been
interpreted as down-dropped areas roughly 5 kilometers (3 miles) wide.
This would imply a region of extension where the crust has been pulled
apart and thus was more easily flooded by the later lava flows.  The
thinner fractures running from the upper left seem to end at the ridge belt
in the center of this mosaic.  These thinner fractures are a continuation
of a pattern seen throughout much of Lavinia and suggest a pattern of
compression over a very large region.  At the bottom of the image,
overlying the ridges, is an impact crater 10-15 kilometers (6-10 miles) in
diameter.  The double or overlapped crater structure and asymmetrical
ejecta pattern suggests that the incoming body broke up shortly before it
hit, leaving closely-spaced craters.  The placement of the crater on top of
the ridges implies it is younger than the ridges; in fact, the crater may
be one of the youngest features in this image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                            Pasadena, CA  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37601  MGN-33
                                        2/22/91

This is a Magellan full-resolution radar mosaic of the Lavinia region of
Venus.  The mosaic is centered at 50 degrees south latitude, 345 degrees
east longitude, and spans 540 kilometers (338 miles) north to south and 900
kilometers (563 miles) east to west.  As with all Magellan images acquired
thus far, the illumination of the radar is from the left-hand side of the
image.  This area shows a diverse set of geologic features.  The bright
area running from the upper right to the lower left is interpreted as part
of a belt of ridges, formed by compression and thickening of the upper
layers of the planet.  The areas between ridges suggest flooding by radar
dark (and thus presumably) smoother lavas.  The varied textures of the
lavas can be seen in the mottled appearance of the plains which are cut by
the ridges; brighter, rougher flows are also quite common.  The
particularly bright flows in the lower right corner are the northern
extension of Mylitta Fluctus.  The bright ridges adjacent to Mylitta
Fluctus at the bottom center of the image also appear to have been affected
by the volcanic activity.  Some of these bright features have been
interpreted as down-dropped areas roughly 5 kilometers (3 miles) wide.
This would imply a region of extension where the crust has been pulled
apart and thus was more easily flooded by the later lava flows.  The
thinner fractures running from the upper left seem to end at the ridge belt
in the center of this mosaic.  These thinner fractures are a continuation
of a pattern seen throughout much of Lavinia and suggest a pattern of
compression over a very large region.  At the bottom of the image,
overlying the ridges, is an impact crater 10-15 kilometers (6-10 miles) in
diameter.  The double or overlapped crater structure and asymmetrical
ejecta pattern suggests that the incoming body broke up shortly before it
hit, leaving closely-spaced craters.  The placement of the crater on top of
the ridges implies it is younger than the ridges; in fact, the crater may
be one of the youngest features in this image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37651
                                  2/25/91

This mosaic of Magellan data in the Fortuna region of Venus, centered at 49
degrees north latitude, 2 degrees longitude, shows two coronae.  Coronae
are large circular or oval structures first identified in Soviet radar
images of Venus.  The structure on the left, Bahet Corona, is about 230
kilometers (138 miles) long and 150 kilometers (90 miles) across.  A
portion of Onatah Corona, over 350 kilometers (210 miles) in diameter, can
be seen on the right of the mosaic.  Both features are surrounded by a ring
of ridges and troughs, which in places cut more radially-oriented
fractures.  The centers of the features also contain radial fractures as
well as volcanic domes and flows.  Coronae are thought to form due to the
upwelling of hot material from deep in the interior of Venus.  The two
coronae may have formed at the same time over a single upwelling, or may
indicate movement of the upwelling or the upper layers of the planet to the
west over time.  A 'pancake' dome, similar to low-relief domes see in the
southern hemisphere, is located just to the southwest of Bahet.  Resolution
of the Magellan data is about 120 meters (400 feet).

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37706
                                  2/19/91

The Magellan synthetic aperture radar (SAR) imaged this unique "triplet
crater," or "crater field" during orbits 418-421 on 21 September 1990.
These craters are 14 kilometers, 11 kilometers, and 9 kilometers in
diameter, respectively, and are centered at latitude -30.1 degrees south
and longitude 345.5 degrees east.  The Magellan Science Team has proposed
the name Stein for this crater field after the American author, Gertrude
Stein.  This name has not yet been approved by the International
Astronomical Union.

The crater field was formed on highly fractured plains.  The impacts
generated a considerable amount of low viscosity "flows" thought to consist
largely of shock-melted target material along with fragmented debris from
the crater.  The three craters appear to have relatively steep walls based
on the distortion in the image of the near and far walls of the craters in
the Magellan radar look direction (from the left).  The flow deposits from
the three craters extend dominantly to the northeast (upper right).

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37707
                                  2/19/91

During orbits 423 through 424 on 22 September 1990, Magellan imaged this
impact crater that is located at latitude 10.7 degrees north and longitude
340.7 degrees east.  This crater is shown as a representative of Venusian
craters that are of the proper diameter (about 15 kilometers) to be
"transitional" in their morphology between "complex" and irregular"
craters.  Complex craters account for about 96 percent of all craters on
Venus with diameters larger than about 15 kilometers; they are thought to
have been formed by the impact of a large, more or less intact, mass of
asteroidal material that has not been excessively effected during its
passage through the dense Venusian atmosphere.  Complex craters are
characterized by circular rims, terraced inner wall slopes, well-developed
ejecta deposits, and flat floors with a central peak or peak ring.
Irregular craters make up about 60 percent of the craters with diameters
less than about 15 kilometers.  Irregular craters are thought to form as
the result of the impact of asteroidal projectiles that have been
aerodynamically crushed and fragmented during their passage through the
atmosphere.  Irregular craters are characterized by irregular and/or
discontinuous rims and hummocky or multiple floors.  The "transitional"
crater shown here has a somewhat circular rim like larger complex craters,
but has the hummocky floor and asymmetric ejecta characteristic of smaller
irregular craters.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37708
                                  2/19/91

Magellan imaged this multiple-floored, irregular impact crater at latitude
16.4 degrees north, longitude 352.1 degrees east, during orbits 481 and 482
on 27 September 1990.  This crater, about 9.2 kilometers in maximum
diameter, was formed on what appears to be a slightly fractured, radar-dark
(smooth) plains.  The abundant, low viscosity flows associated with this
cratering event have, however, filled local, fault-controlled troughs
(called graben).  These shallow graben are well portrayed on this Magellan
image but would be unrecognizable but for their coincidental infilling by
the radar-bright crater flows.  This fortuitous enhancement by the crater
flows of fault structures that are below the resolution of the Magellan
synthetic aperture radar is providing the Magellan Science Team with
valuable geologic information.

The flow deposits from the craters are thought to consist primarily of
shock melted rock and fragmented debris resulting from the nearly
simultaneous impacts of two projectile fragments into the hot (800 degrees
Fahrenheit) surface rocks of Venus.  The presence of the various floors of
this irregular crater is interpreted to be the result of crushing,
fragmentation, and eventual aerodynamic dispersion of a single entry
projectile during passage through the dense Venusian atmosphere.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37786  MGN-34
                                        3/5/91

Thirty-six orbits of full-resolution data from the northern edge of central
Alpha Regio are shown in this image.  The image width is about 600
kilometers (375 miles).  The bright lineated terrain is a series of
troughs, ridges, and faults that are oriented in many directions.  The
lengths of these features generally range from 10 kilometers (6.3 miles) to
50 kilometers (31.3 miles).  The topographic elevation within Alpha Regio
varies over a range of 4 kilometers (2.5 miles).  Local topographic lows,
whose outlines are generally controlled by structures within the central
region, are relatively radar-dark and filled with volcanic lavas.  Source
vents for this volcanism appear as bright spots within the smooth plains
units.  A distinct example of late-stage deformation of Alpha is the narrow
band of southwest-northeast trending faults that disrupt older terrain
between -20 degrees and -22 degrees latitude.  Another interesting feature
is the 35 kilometers (21.9 miles) diameter volcanic edifice located at the
upper right of the image.  The center of the volcano is a local topographic
low and its western edge appears to be breached.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37787  MGN-35
                                        3/5/91

This Magellan image shows part of the northern boundary of Ovda Regio, one
of the large highlands ringing the equator of Venus.  The scene consists
largely of low-relief, rounded linear ridges.  These ridges, 8-15
kilometers (5-9 miles) in width and 30-60 kilometers (20-40 miles) long,
lie mostly along a 100-200 kilometer (60-120 mile) wide slope where the
elevation drops 3 kilometers (2 miles) from Ovda Regio to the surrounding
plains.  Some of the ridges have been cut at right angles by extension
fractures.  Dark material, either lava or windblown dirt, fills the region
between the ridges.  The curvilinear, banded nature of these ridges
suggests that crustal shortening, roughly oriented north-south, is largely
responsible for their formation.  Such crustal shortening was unexpected by
Magellan scientists, who believed that Ovda Regio, a likely site of hot
upwelling from the interior of Venus, should be dominated by volcanism and
crustal extension.  This image, centered approximately at 1 N 81 E,
measures 300 kilometers (190 miles) by 225 kilometers (140 miles) and was
acquired by Magellan in November 1990.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37788  MGN-36
                                        3/5/91

This Magellan image shows part the interior of Ovda Regio, one of the large
highlands ringing the equator of Venus.  Several tectonic events formed
this complex block-fractured terrain.  An underlying fabric of ridges and
valleys strikes NE-SW.  These ridges are spaced 10-20 kilometers (6-12
miles) apart and may have been caused by shortening of the crust at right
angles to this trend.  These structures are cut by throughgoing extension
fractures trending NW-SE, suggesting a later episode of NE-SW extension.
Lastly, the largest valleys, particularly the 20 kilometer (12 mile)-wide
one extending across the image, were filled with dark material, probably
lava.  The complex internal fabric of Ovda Regio attests to a long history
of tectonic deformation.  This image, centered approximately at 1 S 81 E,
measures 225 kilometers (140 miles) by 150 kilometers (90 miles) and was
acquired by Magellan in November 1990.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-37789  MGN-37
                                        3/5/91

This Magellan image is located in the Eistla Region of Venus in the
southern hemisphere and is centered at 5.5 degrees east longitude, 18
degrees south latitude.  It is 122.8 kilometers (76.1 miles) across east-
west and 107.5 kilometers (66.6 miles) across north-south.  North is
oriented towards the top of the image.

Shown in the image is an unusual volcanic edifice unlike all others
previously observed.  It is approximately 65.6 kilometers (40.7 miles)
across at the base and has a relatively flat, slightly concave summit 34.8
kilometers (21.6 miles) in diameter.  The sides of the edifice are
characterized by radiating ridges and valleys that impart a fluted
appearance to the construct.  To the west, the rim of the edifice appears
to have been breached by dark lava flows that emanated from a shallow
summit pit approximately 5.4 kilometers (3.3 miles) in diameter and
traveled west along a channel approximately 5.4 kilometers (3.3 miles) wide
and 26.8 kilometers (16.6 miles) long.  A series of coalescing, collapsed
pits 2-10 kilometers (1.2-6.2 miles) in diameter are located 10 kilometers
(6.2 miles) west of the summit rim.

The edifice and western pits are circumscribed by faint, concentric
lineaments up to 70.3 kilometers (43.6 miles) in diameter.  A series of
north-northwest-trending graben are deflected eastwards around the edifice;
the interplay of these graben and the fluted rim of the edifice produce a
distinctive scalloped pattern in the image.  Several north-northwest-
trending lineaments cut directly across the summit region.

This peculiar volcanic construct is located 25-30 kilometers (15.5-18.6
miles) north of Alpha Regio, a highly deformed region of tessera terrain.
A collection of at least 6 similar volcanoes has been observed near Thetis
Regio, a region of tessera within Aphrodite Terra.  Thus, these unusual
constructs tentatively appear to be spatially associated with regions of
tessera.  The implications of this spatial association on the unusual
morphology of these constructs are being investigated.
                          MAGELLAN PROJECT OFFICE

                                  P-37824
                                  3/11/91

During orbits 404 through 414 on 19-20 September 1990, Magellan imaged a
peak-ring crater that is 50 kilometers in diameter located at latitude 27.4
degrees north and longitude 337.5 degrees east the name Barton has been
proposed by the Magellan Science Team for this crater, after Clara Barton,
founder of the Red Cross; however, the name is tentative pending approval
by the International Astronomical Union.

Barton is just at the diameter size that Venus craters appear to begin to
possess peak-rings instead of a single central peak or central peak complex
like does 75 percent of the craters with diameters between 50 and about 15
kilometers.  The floor of the crater is flat and radar-dark, indicating
possible infilling by volcanic deposits sometime following the impact
event.  Barton's central peak ring is discontinuous and appears to have
been disrupted or separated during or following the cratering process.  The
extremely blocky crater deposits (ejecta) surrounding Barton appears to be
most extensive on the southwest to southeast (lower left to right) side of
the crater.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37831
                                  3/11/91

These dark diffuse circular patterns imaged by the Magellan spacecraft are
thought to be effects generated by the impact of asteroids or comets into
Venus' dense atmosphere.  The three patterns, located in Sedna Planitia
(near 45N and 350E), may represent a sequence in which  a) the impactor was
large enough to penetrate the atmosphere largely intact and striking the
surface producing a bright, rough impact crater and ejecta blanket (right);
b) the impactor was slowed down and broken up with only scattered fragments
striking and scarring the surface (middle); or  c) the impacting body was
so small that it was disrupted and slowed down by the atmosphere creating
no surface impact or scar.  The dark circular regions (30-60 km in
diameter) surrounding these possible impact features are thought to result
from enormous shock waves transmitted to the surface by the atmosphere
which are strong enough to crush surface materials into fine debris which
are dark (non-scattering) in the radar images.  In some cases, notably the
middle image, a brighter region also formed outside of the dark zone.  This
may be a case where the shock was only strong enough to produce coarse
fractures in volcanic flows and in this case increasing the ability to
scatter radar signals.  These features may prove important evidence for
mapping out the types of materials on the surface of the planet.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-37944
                                  3/14/91

This mosaic of Magellan radar images covers 5 percent of the surface of
Venus, approximately the size of the United States and Canada combined.  It
extends 5500 kilometers (3300 miles) across and 4900 kilometers (2900
miles) from top to bottom (north is towards the top), centered on 10 N
latitude, 0 longitude.  A total of 300 north-south image strips were used
to make this mosaic which covers the equatorial regions of Venus known as
Eistla Regio and Tinatin Planitia.  The black stripes are missing data
orbits which may be filled in the future.  Scientists use large mosaics
like these to study the wide variety of geologic features and understand
the regional history of Venus.  Numerous bright circular impact craters are
scattered throughout, ranging in diameter from less than 5 kilometers (3
miles) to 80 kilometers (48 miles).  Some of these are surrounded by dark
halos and streaks which may be formed during the impact process.  The state
of California would just fit inside the large circular fault and fracture
pattern at lower center, named Heng-O Corona.  This feature probably formed
as a result of complex motions in the interior of Venus.  Sif Mons, Gula
Mons, and Sappho Patera, located at upper and left center, are three large
volcanoes.  Numerous lava flows run down from the summits of these
volcanoes.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-37945
                                  3/14/91

This image covers much of Ovda Regio, which forms the western part of
Aphrodite Terra.  It covers an area about 2250 km (1386 miles) wide by 1300
km (800 miles) north to south, and ranges in latitude from 8 north to 12
south and in longitude from 62 to 90.  Ovda Regio is a highland region that
rises over 4 km (2.5 miles) above the surrounding plains.  Magellan images
show a complex surface, with several generations of structures.  A
pervasive fabric of irregular broad domes and ridges and associated
curvilinear valleys was flooded by lava, then fractured.  The circular
feature surrounded by dark lava flows in the western part of the image is a
caldera, or large volcanic collapse pit.  Late-stage extension created long
graben, or fault-bounded valleys, is best seen near the center of the
image.  The northern boundary of Ovda Regio is a steep, curvilinear
mountain belt made up of long, narrow, rounded ridges.  These ridges are
similar in appearance to folded mountain belts on Earth.  Several impact
craters, such as the circular feature on the western margin of the image,
are scattered across the area.  The bright area in the southeast part of
the image indicates the presence of a radar-reflective mineral such as
pyrite.  Most of the highland areas on Venus display a similar bright
signal.  Each pixel of this C2-MIDR-scale product covers an area on the
surface 675 m (2215 feet) across, representing a 9x reduction in resolution
compared to full-resolution data.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-37946
                                  3/14/91

This Magellan image centered at 25 South, 82.5 longitude shows a corona
located about a thousand kilometers south of Aphrodite Terra.  This unnamed
corona is 375 km in diameter; it flanks a north-south trending fracture
zone which meets a smaller corona in the southeast corner of the image.

Coronae are thought to form as a result of heat flow from the interior of
the planet melting the crust.  The molten material rises toward the
surface, causing it to dome.  As it subsequently cools off, the dome
collapses.  The annular ring of fractures and graben, visible in this
image, along with the volcanic domes in the center are characteristic
features of coronae.

Other features associated with the large corona are also noteworthy.  The
bright rim along the northern edge of the corona may represent blocky
debris which has fallen from its flank.  The pancake dome on the western
edge of the corona is a viscous extrusion; it is thought to be younger than
the adjacent graben, since it is superposed on top of them.

The coronae are found amidst lava plains.  Individual flow complexes are
distinguished from each other by variations in radar brightness.  This
suggests subsequent events which resulted in lavas of different textures
(bright greys are blockier, while darker ones are smoother).  The light
grey blotch in the radar-dark circumferential valley on the northwestern
edge of the large corona is a section of the plains, which, because of its
relative height, did not get covered by the non-viscous flow.  This flow
was discharged from the corona through fissures.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-37947
                                  3/14/91

This full-resolution mosaicked image is part of Ovda Regio, which forms the
western part of Aphrodite Terra.  The image is centered at 5 south latitude
and 70 east longitude.  The image includes an area 600 km (370 miles) wide
and 545 km (335 miles) from north to south.  Several events are recorded by
the structures displayed in this image.  The oldest events were the
formation of irregular broad domes and ridges on the order of 20 km (12
miles) wide and of the small-scale structure on the domes and ridges.  The
valleys between these ridges then were flooded by dark lava flows.  An
extensive fracture system radial to the circular feature at the bottom of
the image then cut across the older features.  An impact crater 60 km (37
miles) across is also younger than the flood lava.  Full-resolution images
such as this are providing clues to the origin of Aphrodite Terra, and
therefore important information about Venus tectonics.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-37948
                                  3/14/91

This Magellan mosaic covers an area 1,843 kilometers wide (1145 miles) by
1,613 kilometers high (1002 miles) centered at 45 north latitude and 11
east longitude.  The mosaic shows an area in Bereghinya Planitia.

This area is dominated by volcanism and displays a remarkably diverse set
of surface features.  The most prominent geologic structures are arachnoids
which range in size from 60 to 250 kilometers (37 to 155 miles).
Arachnoids are believed to be of volcanic origin and are marked by
concentric ridges and fractures, and frequently are found in groupings
which form networks connected by fractures which are radial to the
individual arachnoids.  The arachnoids are concentrated in the south east
corner of this mosaic.  Volcanic lava flow fields can be seen associated
with two of the arachnoids (39.5 N, 16 and 40 N, 8.5).  A 300 kilometer
(186 miles) diameter corona (large circular structure) is seen at latitude
48 North and longitude 9 East.  One theory suggests that arachnoids are an
early stage of corona formation.  Other volcanic features are also visible
within this region.  Two types of domes can be found:  small shields
concentrated in two groups (43 N, 8.5o and 42o N, 6o); and several
'pancake' domes at 44o N latitude and 11o longitude, and latitude 44o North
and longitude 7.5o East.  A long sinuous channel is visible in the NE
corner of the image.  The channel comes out of a group of collapse features
associated with a domal structure at 52o N latitude, 19o longitude and
flows for 1100 kilometers (684 miles) to the south.  Finally, six impact
craters can be found in the mosaic, one of which has an anomalous bright
interior floor (43.5o North, 19o East).  This image is a once compressed
mosaic which has been reduced in resolution by a factor of three
(resolution: 225 meters/738 feet) from the resolution available from
Magellan (resolution: 75 meters/245 feet).

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38054
                                  4/2/91

Centered at 22.5 degrees north, 358 degrees east, this Magellan image shows
Sif and Gula Montes, two shield volcanoes thought to be analogous to
volcanoes in the Hawaiian Islands.  Surrounded by the relatively smooth
plains of Eistla Regio, layer upon layer of flow complexes extend more than
500 kilometers (300 miles) from the shield summits into the plains.  Gula
Mons, the taller of the two, stands more than four kilometers above the
surrounding plains.  On Sif Mons flows and fractures radiate from a central
peak dimpled with pit craters.  A fracture zone trends NNW from Gula Mons
to a low relief dome-skirted by lava flows hundreds of kilometers in
length.  A larger fracture zone extends past the lower right-hand corner of
the image.  The dark horseshoe-shaped halo around the crater in the right
center and the streak in the upper center of the image are smooth surfaces
thought to have formed from the interaction of the shock wave of the
impacting object with the surface.  Smooth areas appear dark on the image
since they return fewer radio waves.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38055
                                  4/2/91

Multiple lava flows off the northern slope of Sif Mons, a shield volcano
located approximately 22 degrees north latitude, 352 degrees east
longitude, on the northwestern end of Eistla Regio are seen in this
Magellan image mosaic.  The image is about 600 kilometers (360 miles)
across.  Descending two to three kilometers (1.2-1.8 miles) into the
finger-like plains, the flows form patterns which reveal the topography and
some geologic features.  The flows bend in the direction of the steepest
slope, turning more than 90 degrees on the plains where they eventually
pond.  The long flow in the center flowed around small shield volcanoes but
was thin enough not to cover their peaks.  Radar-bright lineations
associated with the long flow to the east show where lava has been diverted
into troughs.  The darkness around the impact crater on the lower left side
of the image is characteristic of either pulverization during the initial
interaction with the impacting body and the surface or the settling of
particles thrown into the atmosphere after impact.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38056
                                  4/2/91

This is a full resolution mosaic of Magellan orbits 492-524 centered at 25
degrees north latitude, 357 east longitude in southern Sedna Planitia on
Venus.  The irregular circular feature or corona in the right center of the
image is a low dome approximately 100 kilometers (60 miles) in diameter.
The corona is flanked by two major lava flows that extend downslope to the
north for several hundred kilometers.  The entire region lies on the
northern flank of a broad regional highland that contains the two volcanic
centers of Sif Mons and Gula Mons.  The dark streak in the upper left of
the image is associated with a small impact crater.  The object that formed
the crater appears to have broken up in its passage through the dense
Venusian atmosphere.  The radar dark streaks associated with small impact
craters may form from interaction of an intense shock wave with the
surface.  The radar dark surface is smoother than its surroundings.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38088
                                  4/5/91

This is a 225 meter per pixel Magellan radar image mosaic of Venus,
centered at 47 degrees south latitude, 25 degrees east longitude in the
Lada region.  The scene is approximately 550 kilometers (341 miles) east-
west by 630 kilometers (391 miles) north-south.  The mosaic shows a system
of east-trending radar-bright and dark lava flows encountering and
breaching a north-trending ridge belt (left of center).  Upon breaching the
ridge belt, the lavas pool in a vast, radar-bright deposit (covering
approximately 100,000 square kilometers [right side of image]).  The source
caldera for the lava flows, named Ammavaru, lies approximately 300
kilometers (186 miles) west of the scene.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38089
                                  4/12/91

This is a 225 meter per pixel Magellan radar image mosaic of part of Venus,
centered at 51 degrees south latitude, 21 degrees east longitude.  The
scene is approximately 200 kilometers (124 miles) east-west by 160
kilometers (99 miles) north-south.  Running from west to east across the
center of the image is part of a 1200 kilometer (744 miles) long by 20-
kilometer (12-mile) wide lava channel in the Lada Terra region of Venus.
Numerous streamlined structures within the channel attest to the very high
temperature, very fluid lavas (resulting in both thermal and mechanical
erosion) responsible for carving the channel.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38098
                                  4/12/91

This Magellan radar image shows Alpha Regio, a topographic upland
approximately 1300 kilometers across which is centered on 25 degrees south
latitude, 4 degrees east longitude.  In 1963, Alpha Regio was the first
feature on Venus to be identified from earth-based radar.  The radar-bright
area of Alpha Regio is characterized by multiple sets of intersecting
trends of structural features such as ridges, troughs and flat-floored
fault valleys that together form a polygonal outline.  Circular-to-oblong
dark patches within the complex terrain are local topographic lows that are
filled with smooth volcanic lava.  Complex ridged terrains such as Alpha,
formerly called "tessera" in Venera 15/16 and Arecibo radar data, appear to
be a widespread and common surface expression of Venusian tectonic
processes.  Directly south of the complex ridged terrain is a large ovoid-
shaped feature named Eve.  The radar-bright spot located centrally within
Eve marks the location of the prime meridian of Venus.  Magellan radar data
reveals that relatively young lava flows emanate from Eve and embay the
southern margin of the ridged terrain at Alpha.  The mosaic was produced by
Eric De Jong and Myche McAuley in the JPL Multimission Image Processing
Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38101
                                  4/5/91

This Magellan image mosaic shows the largest (275 kilometers in diameter
[170 miles]) impact crater known to exist on Venus at this point in the
Magellan mission.  The crater is located north of Aphrodite Terra and east
of Eistla Regio at latitude 12.5 degrees north and longitude 57.4 degrees
east, and was imaged during Magellan orbit 804 on November 12, 1990.  The
Magellan science team has proposed to name this crater Mead, after Margaret
Mead, the American Anthropologist (1901-1978).  All Magellan-based names of
features on Venus are, of course, only proposed until final approval is
given by the International Astronomical Union-Commission on Planetary
Nomenclature.

Mead is classified as a multi-ring crater with its innermost, concentric
scarp being interpreted as the rim of the original crater cavity.  No inner
peak-ring of mountain massifs is observed on Mead.  The presence of
hummocky, radar-bright crater ejecta crossing the radar-dark floor terrace
and adjacent outer rim scarp suggests that the floor terrace is probably a
giant rotated block that is concentric to, but lies outside of, the
original crater cavity.  The flat, somewhat brighter inner floor of Mead is
interpreted to result from considerable infilling of the original crater
cavity by impact melt and/or by volcanic lavas.  To the southeast of the
crater rim, emplacement of hummocky ejecta appears to have been impeded by
the topography of preexisting ridges, thus suggesting a very low ground-
hugging mode of deposition for this material.  Radar illumination on this
and all other Magellan image products is from the left to the right in the
scene.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38102
                                  4/5/91

Arachnoids, among the more remarkable features found on Venus, are seen on
radar-dark plains in this Magellan image mosaic in the Fortuna region.  The
image is centered at about 40 degrees north latitude, 18 degrees longitude.
Arachnoids are circular to ovoid features with concentric rings and a
complex network of fractures extending outward.  The top image is a mosaic
of Magellan radar images with a resolution of 120 meters.  The Magellan
image is illuminated from the left at an angle of 35 degrees off vertical.
The bottom image was obtained by the Soviet Venera 15/16 radar system.  The
Venera image has a resolution of about 1.5 kilometers (.9 mile).  The
bottom image is illuminated from the right side at an angle of 10 degrees
off vertical.  This image illustrates the importance of multiple mapping
angles for some areas.  Notice in the top image, the bright, irregular lava
flows, just to the left of bottom center.  The rough lava surface is bright
at the Magellan incidence angle.  The lava flows are not detected in the
Venera image at the higher incidence angle which is less sensitive to
roughness variations.  However, the high angle Venera image reveals the
topography which is not easily seen at the Magellan incidence angle.  In
the image, the arachnoids range in size from approximately 50 kilometers
(29.9 miles) to 230 kilometers (137.7 miles) in diameter.  Since arachnoids
are similar in form but generally smaller than coronae (circular volcanic
structures surrounded by a set of ridges and grooves as well as radial
lines), one theory concerning their origin is that they are a precursor to
coronae formation.  The radar-bright lines extending for many kilometers
may have been caused by an upwelling of magma from the interior of the
planet which pushed up the surface to form "cracks."  Radar-bright lava
flows are present in the central part of this image, also indicative of
volcanic activity in this area.  Some of the fractures cut across these
flows, indicating that the flows occurred before the fractures appeared;
such relations between different structures provides good relative age
dating of events.  At present, arachnoids are found only on Venus.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38103
                                  4/5/91

This Magellan image reveals Sacajawea Patera, a large, elongate caldera
located in Western Ishtar Terra on the smooth plateau of Lakshmi Planum.
The image is centered at 64.5 degrees North latitude and 337 degrees East
longitude.  It is approximately 420 kilometers (252 miles) wide at the
base.  Sacajawea is a depression approximately 1-2 kilometers (0.6-1.2
miles) deep and 120 x 215 kilometers (74 x 133 miles) in diameter; it is
elongate in a southwest-northeast direction.  The depression is bounded by
a zone of circumferential curvilinear structures interpreted to be graben
and fault scarps.  These structures are spaced 0.5-4 kilometers (0.3-2.5
miles) apart, are 0.6-4.0 kilometers (0.4-2.5 miles) in width and up to 100
kilometers (62 miles) in length.  Extending up to approximately 140
kilometers (87 miles) in length from the southeast of the patera is a
system of linear structures thought to represent a flanking rift zone along
which the lateral injection and eruption of magma may have occurred.  A
shield edifice 12 kilometers (7 miles) in diameter with a prominent central
pit lies along the trend of one of these features.  The impact crater
Zlata, approximately 6 kilometers (4 miles) in diameter is located within
the zone of graben to the northwest of the patera.  Few flow features are
observed in association with Sacajawea, possibly due to age and state of
degradation of the flows.  Mottled bright deposits 4-20 kilometers (2.5-12
miles) in width are located near the periphery and in the center of the
patera floor within local topographic lows.  Diffuse patches of dark
material approximately 40 kilometers (25 miles) in width are observed
southwest of the patera, superposed on portions of the surrounding graben.
The formation of Sacajawea is thought to be related to the drainage and
collapse of a large magma chamber.  Gravitational relaxation may have
caused the resultant caldera to sag, producing the numerous faults and
graben that circumscribe the patera.  Regions of complex, highly deformed
tessera-like terrain are located north and east of the patera and are seen
in the upper portion of the image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38104
                                  4/5/91

This is a Magellan radar image covering a 105-kilometer (63- mile) by 45-
kilometer (27-mile) region near Hestia Rupes on the northwestern corner of
Aphrodite Terra.  The complex network of narrow (<1 kilometer) fractured in
the center of the image extends for approximately 50 kilometers (31 miles).
This network exhibits tributary-like branches similar to those observed in
river systems on Earth.  However, the angular intersections of tributaries
suggest tectonic control.  These features appear to be due to drainage of
lava along preexisting fractures and subsequent collapse of the surface.
The underlying tectonic fabric can be observed in the northeast trending
ridges which predate the plains.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38139
                                  4/19/91

This complex crater in the Navka region of Venus was mapped by Magellan on
September 26-27, 1990 during orbits 459 and 460.  The crater has a diameter
of 22 kilometers (13.6 miles) and is located at latitude 5.75 degrees
south, longitude 349.6 degrees east.  It has the terraced walls, flat
radar-dark floor, and central peak that are characteristic of craters
classified as "complex."  The central peak on its floor is unusually large.
Flow-like deposits extend beyond the limits of the coarser rim deposits on
its west and southwest.  Like about half of the craters mapped by Magellan
to date, it is surrounded by a local, radar-dark halo.

Buck, the proposed name for this crater honors Pearl S. Buck, American
author (1892-1973).  Proposed names for all features on planetary bodies
are provisional until formally adopted by the International Astronomical
Union.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38140
                                  4/19/91

This beautiful impact crater in the Lada region of Venus was mapped by
Magellan on October 11, 1990 during orbits 585 through 595.  It is located
at latitude 30.75 degrees south, longitude 20.20 degrees east.  The crater,
67 kilometers (41.5 miles) in diameter, is distinctive because unusual,
feather-like flows extend from the west and northwest sides of its rim.
It's radar-bright floor has unique physical and electrical properties that
are presently being evaluated by members of the Magellan Science Team.  The
crater is classified as a "peak-ring" crater because its floor has a
concentric ring of hills, or peak-ring.  In this crater, the peak-ring has
been somewhat disrupted and is not the nearly perfect ring seen in some
other large craters mapped by Magellan.  A large, radar-bright, parabola-
shaped deposit (not shown here) extends west from the crater for many
hundreds of kilometers.  It is thought to result from the interaction of
fine crater ejecta with the upper atmospheric winds that are dominant in
the equatorial region.  Similar west-facing deposits observed by Magellan
are associated with a dozen or so other bright-floored craters in the
equatorial region.

Stuart, the proposed name of this crater honors Mary Stuart, Queen of Scots
(1542-1587).  Proposed names for all features on planetary bodies are
provisional until formally adopted by the International Astronomical Union.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38141
                                  4/19/91

This Magellan full-resolution mosaicked image shows the central and
northern parts of Ovda Regio, one of the large highlands ringing the
equator of Venus that make up Aphrodite Terra.  The complex structures
displayed in this image indicate a long history involving several tectonic
events.  The northern third of the image is dominated by low-relief,
rounded linear ridges that trend roughly east-west.  These ridges lie along
a 100-200 kilometer (60-120 mile) wide slope where the elevation drops 3
kilometers (2 miles) from Ovda Regio to the surrounding plains.  The ridges
have been interpreted as resulting from crustal shortening (compression)
oriented approximately north-south.  The topographic expression of the
ridges is reminiscent of that displayed by folded mountain belts on Earth.
Shorter, broader ridges and valleys which form the underlying fabric in the
central part of Ovda may be another manifestation of this crustal
shortening.  Both types of ridges are cut by through-going fractures and
graben (fault-bounded valleys), indicating that an episode of northeast-
southwest extension followed the compressional event.  The youngest event
was flooding of low-lying areas by smooth (radar-dark) lava flows.  The
importance of crustal shortening in the formation of the equatorial
highlands was not recognized prior to production of Magellan images.
Instead, scientists expected that Ovda Regio, a likely site for the
upwelling of hot material from the interior of Venus, should be dominated
by volcanism and crustal extension.  This image, centered at 0 degrees
north latitude, 82 degrees east longitude, measures approximately 535
kilometers (334 miles) by 600 kilometers (375 miles) wide and was acquired
by Magellan in November 1990.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38142
                                  4/19/91

This Magellan full-resolution mosaic shows an area in Ishtar Terra on
Venus, centered at 65 degrees north latitude and 6 degrees east longitude.
The prominent circular feature is Cleopatra, an impact crater, 100
kilometer (62 miles) in diameter.  Cleopatra lies on the eastern slopes of
Maxwell Montes, the tallest mountain range on Venus at almost 11 kilometers
(6.8 miles) above the mean planetary radius.  The western slopes of Maxwell
Montes are very steep while the eastern slopes descend gradually.  The
radar-bright return throughout most of the image is present on Venus at
high altitudes.  This phenomenon is thought to indicate the presence of a
radar reflective mineral such as pyrite which is stable at the pressure and
temperature found at higher altitudes.  The ridges and troughs throughout
the image formed from compression of the surface.  It was not determined
whether Cleopatra was a volcanic or impact crater until high-resolution
Magellan data were received.  The rough, surrounding ejecta is visible in
Magellan images, distinguishing it as a large double-ring impact basin
similar to those found on other planetary bodies.  Lava from impact melt or
volcanism triggered by the impact breached the crater rim and filled the
troughs in the upper right-hand corner of the image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38143
                                  4/19/91

This crater, partly flooded by volcanic lavas, was mapped by Magellan on
September 20, 1990 during orbits 411 through 418.  It is located in the
Lavinia region of Venus at 59.5 degrees south latitude and 354.5 east
longitude.  It is one of the very few impact craters that has been
documented by Magellan to be actually in the process of elimination by
volcanic resurfacing, and with a diameter of 63 kilometers (39 miles), it
is the largest of these craters.  The large, trough-like depression on the
southwest (lower left) side is a rille or channel through which lava once
flowed.  A remnant of rough radial ejecta is preserved outside the crater's
southeast rim.  The presence of partly lava-flooded craters, such as this,
are important to our understanding of the rate of resurfacing on Venus by
volcanism.  Resolution of the Magellan data is about 120 meters (400 feet).

Alcott, the name proposed for this crater, honors Louisa May Alcott,
American author (1832-1888).  Proposed names for all features on planetary
bodies are provisional until formally adopted by the International
Astronomical Union.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38156
                                  5/10/91

This Magellan image, centered at 42.5 degrees south latitude, 6 degrees
east longitude shows Pandora Corona.  It is 350 kilometers (210 miles) in
diameter and is located in Lada Terra.  It lies beside a northwest-
southwest trending fracture zone.  Many of the radial fractures in
Pandora's interior appear to connect with this fracture zone, suggesting
that both features may have formed at the same time.

Coronae are circular to elliptical features marked by a ring of concentric
ridges, and are thought to result from heat flow from the planet's
interior.  As hot material rises, it weakens the upper layers of the planet
and causes the surface to dome upwards.  Then s the region cools, the dome
begins to subside.  As the upper layers rise and subside, they are
subjected to stresses which crack the surface, creating both circular and
radial fractures.

The medium grey lobes on the southern side of Pandora's outer ring are lava
flows which began in fissures, or cracks, along the outer ring.  The
irregularly shaped features, aligned in a radial direction, are thought to
be lava collapse tubes.  Molten lava can flow in long channels near the
surface; when the flow stops, these structures may become unstable and
collapse, creating depressions on the surface.  The small crater in the
northeast corner of the image is 12 kilometers (7.2 miles) in diameter.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38160
                                  4/23/91

This Magellan image is centered at 17 degrees north latitude and 62.5
longitude in the northwestern Ovda Region of Venus.  The image, which is
100 kilometers (62 miles) in width and 70 kilometers (43.4 miles) in
length, is a mosaic of orbits 829-834.  The image shows some spectacular
wind streaks 500 kilometers (300 miles) northeast of the crater Mead.  Mead
is the largest impact crater known to exist on Venus with a diameter of 275
km (170 miles).  The large explosion associated with the impact spread
debris as much as 500 kilometers away from Mead on to the surrounding
plains.  The streaks in this image most likely represent debris from the
impact that has been modified by surface winds.  It is difficult to
determine whether there are bright streaks on top of darker terrain or dark
streaks on top of brighter terrain.  If the streaks represent radar-bright
debris then the wind is blowing from the northwest to the southeast.  If
the streaks are composed of radar-dark material, then the wind direction is
reversed.  During the second cycle, Magellan scientists will look at this
area again to determine if there has been any movement of the streaks.
Movement will indicate active aeolian modification on the surface of Venus.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38169
                                  4/19/91

This is a full resolution mosaic centered at 25 degrees north latitude, 351
east longitude.  The region is approximately 160 kilometers (100 miles)
across.  It shows a series of complex lava flows which emerge from the
northern flank of Sif Mons, a large volcano just to the south.  Several of
the flows occupy narrow troughs formed by long fractures.  A sequence of
events that can be inferred from this image is the formation of the dark
background plains by eruptions of extremely fluid volcanic material, and
the formation of the small shield volcanoes on the plains surface that can
be seen in the upper left part of the image.  Next, the region was domed
upward probably by heat from the interior of Venus that ultimately caused
magmas to break out from the surface near the summit regions forming the
Sif volcanic structure and its associated flank eruptions which can be seen
in this image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38170
                                  5/10/91

This 48-kilometer-diameter "complex" crater with its radar-dark flat floor
and its central peak of hills is one of the three similar craters mapped in
the "crater farm area".  The crater is located at latitude 26.35 degrees
south, longitude 337.25 degrees east.  The radar-bright ejecta deposits are
nearly symmetric around the crater except for their absence in a small
sector on the northwest rim (upper left side).  A thin, radar-dark, flow-
like deposit has emanated from the rim deposits on the south side and
extends to the southwest.  The narrow, radar-bright bands outlining the
deposit are thought to result from the piling up and roughening of the
material along its sides.

Danilova, the name proposed for this crater, honors a Russian ballet
dancer.  Proposed names for all features on planetary bodies are
provisional until formally adopted by the International Astronomical Union.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38171
                                  4/19/91

This is a full-resolution mosaicked image centered at 24.5 degrees north,
350.5 degrees east.  Located on the northern slope of Sif Mons, where
elevated Eistla Regio meets Sedna Planitia (plains) this area displays a
simple sequence of events.  The circular features, no more than 5
kilometers (3.1 miles) in diameter are small shield volcanoes, features
commonly found on the Earth.  The dark background plains and the shield
volcanoes both formed from the eruption of very fluid lava.  Then, several
layers of lava flows covered each other, each one successively brighter
indicating that they become blockier in texture and more viscous (sticky)
in consistency with time.  The summits of the shield volcanoes protrude
from the flow without being covered.  After the flows were emplaced,
fractures formed as the new surface expanded.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38172
                                  5/01/91

This Magellan full-resolution image shows Maxwell Montes, and is centered
at 65 degrees north latitude and 6 degrees east longitude.  Maxwell is the
highest mountain on Venus, rising almost 11 kilometers (6.8 miles) above
mean planetary radius.  The western slopes (on the left) are very steep,
whereas the eastern slopes descend gradually into Fortuna Tessera.  The
broad ridges and valleys making up Maxwell and Fortuna suggest that the
topography resulted from compression.  Most of Maxwell Montes has a very
bright radar return; such bright returns are common on Venus at high
altitudes.  This phenomenon is thought to result from the presence of a
radar reflective mineral such as pyrite.  Interestingly, the highest area
on Maxwell is less bright than the surrounding slopes, suggesting that the
phenomenon is limited to a particular elevation range.  The pressure,
temperature, and chemistry of the atmosphere vary with altitude; the
material responsible for the bright return probably is only stable in a
particular range of atmospheric conditions and therefore a particular
elevation range.  The prominent circular feature in eastern Maxwell is
Cleopatra.  Cleopatra is a double-ring impact basin about 100 kilometers
(62 miles) in diameter and 2.5 kilometers (1.5 miles) deep.  A steep-
walled, winding channel a few kilometers wide breaks through the rough
terrain surrounding the crater rim.  A large amount of lava originating in
Cleopatra flowed through this channel and filled valleys in Fortuna
Tessera.  Cleopatra is superimposed on the structures of Maxwell Montes and
appears to be undeformed, indicating that Cleopatra is relatively young.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38173
                                  5/01/91

This image, centered at 21.5 degrees north, 359.5 degrees east is part of
an F-MIDR (Full-resolution Mosaicked Image Data Record) covering Magellan
orbits 492-523.  This is a close look at Gula Mons, a shield volcano 4
kilometers (13100 feet) in height in northwestern Eistla Regio on Venus.
This type of volcanism is similar to that of the Hawaiian islands in that
it is thought have resulted from hot material rising from the interior and
heating the crust.  Both volcanoes formed from hot, fluid lava which
erupted non-explosively.  The radar-bright area consists of both the summit
(circular southwestern part) and radial troughs and scarps trending to the
northeast down the slope of Gula Mons.  Evidence of regional expansion of
the crust is expressed in this area by the radial troughs or graben and a
larger scale fracture complex which trends southeast from the bottom right
corner of the image.  The very thin lineations which extend outward from
the summit before bending southward are thought to be the surface
expression of a dike system (planes of solidified molten rock within
bedrock).  The dikes formed between intermittent outflows of lava which
descend from the summit of Gula Mons.  This is apparent from the
observation that some dikes cut the flows while others are covered by them.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38177
                                  4/23/91

This Magellan image is centered at 55 degrees north latitude, 348.5 degrees
longitude, in the eastern Lakshmi region of Venus.  The image, which is 300
kilometers (180 miles) in width and 230 kilometers (138) miles in length,
is a mosaic of orbits 458-484.  The image shows a relatively flat plains
region composed of many lava flows.  The dark flows most likely represent
smooth lava flows similar to pahoehoe flows on Earth while the brighter
lava flows are rougher flows similar to aa flows on Earth.  The rougher
flows are brighter because the rough surface returns more energy to the
radar than the smooth flows.

Situated on top of the lava flows are three dark splotches.  Because of the
thick Venusian atmosphere, the small impactors break up before they reach
the surface.  Only the fragments from the broken up impactor are deposited
on the surface and these fragments produce the dark splotches in this
image.  The splotch at the far right (east) has a crater centered in it,
indicating that the impactor was not completely destroyed during its
journey through the atmosphere.  The dark splotches in the center and to
the far left in this image each represent an impactor that was broken up
into small fragments that did not penetrate the surface to produce a
crater.  The dark splotch at the left has been modified by the wind.  A
southwest-northwest wind flow has moved some of the debris making up the
splotch to the northeast where it has piled up against some small ridges.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38197
                                  5/01/91

This Magellan image is a mosaic of eight orbits.  The image is centered at
17.4 degrees north latitude and 338.6 degrees longitude, in the northern
Navka region of Venus.  It is 125 kilometers (75 miles) in width and 100
kilometers (60 miles) in length.  The image shows radar-dark linear wind
streaks on top of radar-dark lava flows.  The streaks indicate a southeast-
northwest wind direction.  The darkness of the streaks indicates that the
streaks are made up of small, fine material that cannot return a strong
radar signal to the Magellan spacecraft.  The radar-dark lava flows that
the streaks lie upon are radar-dark because they are smoother than the
rougher, radar-bright lava flows to the left (west).  Because the streaks
are associated with lava flows, they may be composed of fine ash from the
volcanic eruption that produced the lava flows.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38218
                                  5/01/91

A portion of Western Eistla Regio is displayed in this three-dimensional
perspective view of the surface of Venus.  The viewpoint is located 700
kilometers (430 miles) southeast of Gula Mons at an elevation of 1.2
kilometers (0.74 miles).  A rift valley, shown in the foreground, extends
to the base of Gula Mons, a 3 kilometers (1.86 miles) high volcano.  We are
looking to the northwest with Gula Mons appearing at the right on the
horizon.  Gula Mons is located at approximately 22 degrees north 359
degrees east.  Sif Mons, a volcano with a diameter of 300 kilometers (180
miles) and a height of 2 kilometers (1.2 miles), appears to the left of
Gula Mons, in the background.  Magellan Synthetic Aperture Radar data is
combined with radar altimetry to develop a three-dimensional map of the
surface.  Ray tracing is used to generate a perspective view from this map.
Simulated color and radar-clinometry are used to enhance small scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced at the JPL
Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall and
Myche McAuley, and is a single frame from the movie released at the March
5, 1991 Press Conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38269
                                  6/5/91

This Magellan image, centered at 10 degrees north latitude, 188 east
longitude shows the volcano Sapas Mons located in the broad equatorial rise
known as Atla Regio (8 degrees north latitude, 188 degrees east longitude).
Sapas Mons is about 400 kilometers (250 miles) across and rises 1.5
kilometers (0.9 miles) above the local terrain.  It is about 4.5 km above
the mean planetary radius.  The flanks of the volcano are composed of
numerous overlapping lava flows.  The dark flows on the lower right are
thought to be smoother than the brighter flows near the central part of the
volcano.  Many of the flows appear to have erupted along the flanks of the
volcano, rather than from the summit.  This type of flank eruption is
common on large volcanoes on the Earth, such as the Hawaiian volcanoes.
The summit area consists of a pair of flat-topped mesas, whose smooth tops
give a relatively dark appearance in the radar image.  Also seen near the
summit are groups of pits, some as large as 1 kilometer (0.6 miles) across.
These are thought to have formed when underground chambers of magma were
drained through other subsurface tubes, leading to a collapse at the
surface.  A 20-kilometer (12.5-mile) diameter impact crater northeast of
the volcano is partially buried by the lava flows.  Little was known about
the Atla Regio rise prior to Magellan.  The new data, taken in February
1991, show the region to be composed of at least five large volcanic
edifices such as Sapas Mons, which are commonly linked by complex systems
of fractures or rift zones.  By analogy with similar features on the Earth,
Atla Regio is thought to result from upwellings of large volumes of molten
rock from the interior of Venus known as "hot spots."

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38281
                                  6/19/91

This Magellan image from the Atla region of Venus shows several types of
volcanic features and superimposed surface fractures.  The image is
approximately 350 kilometers (217 miles) across, centered at 9 degrees
south latitude, 199 degrees east longitude.  Lava flows emanating from
circular pits or linear fissures form flower-shaped patterns in several
areas.  A collapse depression approximately 20 kilometer by 10 kilometer
(12 by 4 mile) near the center of the image is drained by a lava channel
approximately 40 kilometer (25 mile) long.  Numerous surface fractures and
graben (linear valleys) criss-cross the volcanic deposits in north to
northeast trends.  The fractures are not buried by the lavas, indicating
that the tectonic activity post-dates most of the volcanic activity.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38283
                                  6/14/91

This Magellan full-resolution image shows Jeanne crater, a 19.5 kilometer
(12 mile) diameter impact crater.  Jeanne crater is located at 40.0 degrees
north latitude and 331.4 degrees longitude.  The distinctive triangular
shape of the ejecta indicates that the impacting body probably hit
obliquely, traveling from southwest to northeast.  The crater is surrounded
by dark material of two types.  The dark area on the southwest side of the
crater is covered by smooth (radar-dark) lava flows which have a strongly
digitate contact with surrounding brighter flows.  The very dark area on
the northeast side of the crater is probably covered by smooth material
such as fine-grained sediment.  This dark halo is asymmetric, mimicking the
asymmetric shape of the ejecta blanket.  The dark halo may have been caused
by an atmospheric shock or pressure wave produced by the incoming body.
Jeanne crater also displays several outflow lobes on the northwest side.
These flow-like features may have formed by fine-grained ejecta transported
by a hot, turbulent flow created by the arrival of the impacting object.
Alternatively, they may have formed by flow of impact melt.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38284
                                  6/14/91

This image of Sachs Patera on Venus is centered at 49 degrees north, 334
degrees east.  Defined as a sag-caldera, Sachs is an elliptical depression
130 meters (81 feet) in depth, spanning 40 kilometers (25 miles) in width
along its longest axis.  The morphology implies that a chamber of molten
material drained and collapsed, forming a depression surrounded by
concentric scarps spaced 2-to-5 kilometers (1.2-to-3 miles) apart.  The
arc-shaped set of scarps, extending out to the north from the prominent
ellipse, is evidence for a separate episode of withdrawal; the small lobe-
shaped extension to the southwest may represent an additional event.
Solidified lava flows 10-to-25 kilometers (6-to-16 miles) long, give the
caldera its flower-like appearance.  The flows are a lighter tone of gray
in the radar data because the lava is blockier in texture and consequently
returns more radar waves.  Much of the lava, which was evacuated from the
chamber, probably traveled to other locations underground, while some of it
may have surfaced further south.  This is unlike calderas on Earth, where a
rim of lava builds up in the immediate vicinity of the caldera.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38285
                                  6/14/91

This Magellan image, which is 50 kilometers (31 miles) in width and 80
kilometers (50 miles) in length, is centered at 11.9 degrees latitude, 352
degrees longitude in the eastern Navka Region of Venus.  The crater, which
is approximately 8 kilometers (5 miles) in diameter, displays a butterfly
symmetry pattern.  The ejecta pattern most likely results from an oblique
impact, where the impactor came from the south and ejected material to the
north.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38286
                                  6/14/91

Crater Stephania is located at 51.3 degrees latitude, 333.3 degrees
longitude in northern Sedna Planitia on Venus.  With a diameter of 11
kilometers (6.8 miles) it is one of the smaller craters on Venus.  Because
many small meteoroids disintegrate during their passage through the dense
atmosphere, there is an absence of craters smaller than 3 kilometers (1.9
miles) in diameter, and even craters smaller than 25 kilometers (15.5
miles) are relatively scarce.  The apron of ejected material suggests that
the impacting body made contact with the surface from an oblique angle.
Upon closer observation it is possible to delineate secondary craters,
impact scars from blocks ejected from the primary crater.  A feature
associated with this and many other Venusian craters is a radar-dark halo.
Since dark radar return signifies a smooth surface, it has been
hypothesized that an intense shock wave removed or pulverized previously
rough surface material or that a blanket of fine material was deposited
during or after the impact.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38287
                                  6/14/91

This Magellan full-resolution mosaicked image shows an unnamed crater
approximately 13 kilometer (8 mile) diameter impact crater.  This crater is
located at 6.0 degrees north latitude, 331.9 degrees longitude.  The
asymmetry of the ejecta blanket indicates that the impacting body probably
hit obliquely, traveling from south to north.  Debris kicked up by the
impact created secondary craters to the north.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38288
                                  6/14/91

This irregularly-shaped crater is located at 51.7 degrees south latitude,
348.3 degrees longitude, with an average diameter of about 11 kilometers (7
miles).  While areas east and southwest of the crater appear to be blockier
than the rest of the bright ejecta, this crater does not have the usual
well-defined lobate ejecta flows.  Both the crater and the associated
ejecta have asymmetrical forms.  Impact craters on Venus in this size range
commonly display these irregular features.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38290
                                  6/14/91

This Magellan image, which is 40 kilometers (25 miles) in width and 76
kilometers (47 miles) in length, is centered at -21.4 degrees latitude,
335.2 degrees longitude in the northern Lavinia Region of Venus.  The image
shows an irregular crater of approximately 14-kilometer (8.7-mile) mean
diameter.  The crater is actually a cluster of four separate craters that
are in rim contact.  The noncircular rims and multiple, hummocky floors are
probably the result of the breakup and dispersion of an incoming meteoroid
during passage through the dense Venusian atmosphere.  After breaking up,
the meteoroid fragments impacted nearly simultaneously, creating the crater
cluster.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38291
                                  6/14/91

This Magellan full-resolution mosaicked image shows an intermediate-sized
volcano about 50 kilometers (31 miles) in diameter.  This volcano is
located in northern Lada Terra at 42.6 degrees south latitude, 27.9 degrees
longitude.  The volcano has a central caldera-like structure (depression)
about 12 kilometers (7 miles) in diameter, surrounded by an asymmetrical
ring of narrow flows that extend for 15-to-40 kilometers (9-to-25 miles).
To the north and northeast, an apron of older lava flows underlies the
annulus and extends up to an additional 60 kilometers (37 miles).  The
darker stripes within the mosaic are an artifact of the radar collection;
these are individual orbits in which the spacecraft's antenna was pointing
very slightly off-target.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38292  MGN-56
                                        7/26/91

This Magellan full-resolution mosaic, centered at 55 degrees south, 354
east shows the lava flows of Mylitta Fluctus in Lavinia Planitia (plains)
on Venus.  The entire flow complex spans over 800 kilometers (496 miles)
from north to south and 380 kilometers (236 miles) from east to west.
Individual flows range in width from less than 3 to 125 kilometers (about 2
to 78 miles).  The flows originate from a 700 meter (2,300 feet) high
volcano located on a possible rift zone outside the image to the south.
The northern flank of the volcano is seen on the southern edge of the image
and consists of a diffusely bright, fan-shaped area of relatively thin
flows.  The main flow field descends 1 kilometer (.62 miles) into the
plains until it encounters more level ground, where individual flows pond
and widen.  A variety of flow features such as braided channels, levees,
and roughness or texture changes within flows further our understanding of
the conditions of the eruption and the nature of the lava itself.  These
flows are thought to have been very fluid and similar to lunar mare basalts
and terrestrial flood basalts.
                          MAGELLAN PROJECT OFFICE

                                  P-38293
                                  7/1/91

This is a Magellan radar mosaic of the Lavinia region of Venus.  The mosaic
is centered at 45 degrees south latitude and 350 degrees longitude and
covers a region 1840 kilometers (1100 miles) by 1600 kilometers (970
miles).  This topographically low region exhibits many diverse geologic
features.  The dominant structures are the tectonically deformed lineament
belts which appear on this image as concentrated regions of parallel bright
lines.  These belts, which are slightly more elevated than the surrounding
plains, consist of a series of ridges thought to be formed by the
compression of the upper layer of the planet.  Individual ridges within a
belt are a few kilometers wide and tens of kilometers long.  Small (less
than 20 kilometers or 12 mile diameter) circular patches in the plains,
such as those located in the upper left of the image, are believed to be
small volcanic shields.  The bright and dark lobes in the bottom center and
middle right of the image are volcanic deposits that have flowed from
source regions not seen in this image.  The bottom flow complex is the
northern part of Mylitta Fluctus, a region of vast outpourings of lava over
800 kilometers (480 miles) long.  The northern part of this flow can be
seen to surround a few ridges, suggesting that the ridge belts formed
before the last eruptions.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38293  MGN-57
                                        7/26/91

This is a Magellan radar mosaic of the Lavinia region of Venus.  The mosaic
is centered at 45 degrees south latitude and 350 degrees longitude and
covers a region 1,840 kilometers (1,100 miles) by 1,600 kilometers (970
miles).  This topographically low region exhibits many diverse geologic
features.  The dominant structures are the tectonically deformed lineament
belts which appear on this image as concentrated regions of parallel bright
lines.  These belts, which are slightly more elevated than the surrounding
plains, consist of a series of ridges thought to be formed by the
compression of the upper layer of the planet.  Individual ridges within a
belt are a few kilometers wide and tens of kilometers long.  Small (less
than 20 kilometers or 12 mile diameter) circular patches in the plains,
such as those located in the upper left of the image, are believed to be
small volcanic shields.  The bright and dark lobes in the bottom center and
middle right of the image are volcanic deposits that have flowed from
source regions not seen in this image.  The bottom flow complex is the
northern part of Mylitta Fluctus, a region of vast outpourings of lava over
800 kilometers (480 miles) long.  The northern part of this flow can be
seen to surround a few ridges, suggesting that the ridge belts formed
before the last eruptions.
                          MAGELLAN PROJECT OFFICE

                                  P-38294
                                  8/2/91

This Magellan image of Venus is centered at 25 degrees south latitude and 3
degrees east longitude.  Most of this image is of complex ridge terrain,
otherwise known as tessera.  Relationships between ridges and troughs may
indicate a time sequence of deformation, so a series of events can be
hypothesized.  These clues give insight into the complex nature of
tectonics in tessera areas.  This image shows at least two different kinds
of tessera and several examples of intratessera plains.

In the upper northwest quadrant an orthogonal patterned tessera is most
pronounced where ridges and troughs trend west-northwest.  Spaced 20 to 50
kilometers (12 to 31 miles) apart and over 50 kilometers (31 miles) in
length, these troughs and ridges commonly intersect and disrupt smaller
(less than 25 kilometers [16 miles] long) north-northeast-trending
structures, predominantly troughs spaced about 1 kilometer (.6 mile) apart.

Another kind of tessera seen in the southwest quadrant of the image is a
complex tessera.  Two different scales of structures are seen.  The first
consists of ridges and troughs in arcuate, loop-like patterns at the
spacing of 10 to 20 kilometers (6 to 12).  On the spacing of 1 kilometer
(.6 miles) or less, structures consist of scarps, fractures and troughs.
These smaller structures tend to follow local trends set by the larger
loop-like structures.

Intratessera plains are the dark, smooth patches scattered throughout the
tessera.  The very faint small bumps are shield volcanoes that are less
than 5 kilometers (3 miles) across.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38295
                                  7/26/91

This Magellan full-resolution mosaic of Venus centered at 60.3 degrees
north ,337.5 degrees east shows Danu Montes (mountains) bordering on
Lakshmi Planum (plains).  Rising almost two kilometers (1.25 miles) above
the adjacent plains, the mountains appear as ridges and troughs, implying
crustal shortening by compressional forces.  The highly deformed terrain,
known as tessera, is present in most of the lower right portion of the
image.  Deep gorges separate continuous lineaments of the folded terrain,
suggesting that an episode of expansion split apart the surface proceeding
the compression.  The largest and most prominent chasm in the image spans a
width of 20 kilometers (12.5 miles) with a length of 75 kilometers (46.88).
A popular theory on the processes and history of this region suggests that
after the crust bunched together under compression, it heated up, became
more supple and slumped into the plains.  There are also round and elongate
pits; some of them have long channels extending more than 75 kilometers
(46.88 miles) out into the plains.  The volcanic plains of Lakshmi Planum
span a maximum of 2100 kilometers (1302 miles) in length and a maximum of
1500 kilometers (930 miles) in width.  Only part of the southern tip is
visible in this image.  The plains are relatively high and level, varying
from 3 to 4 kilometers (1.86 to 2.48 miles) above mean planetary radius.
The fractured plains in the lower left corner of the image are over 2.5
kilometers (1.55 miles) lower in elevation than Lakshmi Planum.  In the
lower right portion of the image a crater, 25 kilometers (15.5 miles) in
diameter appears relatively radar bright.  Another crater at the bottom of
the image where the fractured plains meet the tessera is similar in size
but has been highly degraded by dynamic crustal forces.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38296
                                  7/26/91

This Magellan full-resolution mosaic of Venus, centered at 69.5 degrees
north, 338 degrees east shows the southern part of Freyja Montes
(mountains) descending westward into the elevated volcanic plains known as
Lakshmi Planum.  Ridges trending north-south are thought to be either
folding of the crust or low angle thrust faults, where one part of the
surface slides underneath the other causing it to bunch and buckle-up.
Such features result from lateral compression of the surface.  Parallel to
these ridges are graben (troughs), a surface expression of lateral
extension.  A likely scenario for this area is that the crust bunched up
and subsequently fell apart under its own weight.  The fact that some of
the graben cut across the ridges offers further evidence that the events
occurred in that time sequence.  The same tectonics on a smaller scale are
thought to have been responsible for the tortoise shell appearance of the
oval-shaped feature at the top right portion of the image.  Its collapse
may have contributed to the formation of the ridges flanking the feature.
Smooth volcanic plains, which are imaged by radar as uniformly dark areas,
fill in the lower elevations of the fluctuating topography.  In these
areas, lava has been extruded, often without an obvious vent.  Wrinkles or
thrust faults taper off into the vast volcanic plains of Lakshmi where
remnants of fractured plains are surrounded by newer, relatively
featureless plains.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38297
                                  6/19/91

This is a Magellan radar mosaic of the Navka region of Venus.  The mosaic
is centered at 15 degrees north latitude and 352 degrees longitude and
covers a region 1840 kilometers (1100 miles) east-west and 1600 kilometers
(970 miles) north-south.  The north-south black bars are regions of missing
data.  The southern halves of two large volcanoes are located at the top of
the image.  Sif Mons, at the top-center, is approximately 500 kilometers
(300 miles) across and rises about 2.5 kilometers (1.5 miles) above the
average elevation of the planet's surface.  The 30 kilometer (18 mile)
circular region (called a caldera) is the probable source of the many
lobate lava flows that radiate downhill.  A 10 kilometer (6 mile) diameter
impact crater surrounded by a dark halo is located on the slopes of the
volcano 225 kilometers (135 miles) southwest of the central caldera.  To
the east of Sif is Gula Mons, a 550 kilometers (330 mile) diameter volcano
that is 3.5 kilometers (2.1 miles) high.  The summit of Gula Mons is
composed of 2 calderas joined by a belt of linear deformation.  The
southwestern of these 2 calderas is the bright circular region in the upper
right of the image.  As at Sif Mons, bright and dark flows radiate downhill
from the volcano.  The concentrated region of bright lines southeast of
Gula is the near end of a rift zone that intersects Gula at the caldera.
Many other bright linear features cross the mottled plains that surround
the volcanoes.  In the center of the image is a 40 kilometer (24 mile)
diameter impact crater.  The bright halo surrounding the crater may be a
fairly thin deposit, since the fractures on the underlying plains can still
be seen.  These plains are probably volcanic in origin; the boundaries
between different areas of plains often have a flow-like morphology.  There
is another smaller volcano in the lower left of the image, emphasizing that
this region of Venus has been very active volcanically.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38298
                                  6/19/91

This is a Magellan radar mosaic of the Lavinia region of Venus.  The mosaic
is centered at 45 degrees south latitude and 350 degrees longitude and
covers a region 1840 kilometers (1100 miles) east-west and 1600 kilometers
(970 miles) north-south.  The north-south black bars are regions of missing
data.  This topographically low region exhibits many diverse geologic
features.  The dominant structures are the tectonically deformed lineament
belts which appear on this image as concentrated regions of subparallel
bright lines.  These belts, which are slightly more elevated than the
surrounding plains, are interpreted to be composed of a series of ridges
formed by the compression of the upper layer of the planet.  Individual
ridges within a belt are a few kilometers wide and tens of kilometers long.
The medium-gray plains surrounding these ridge belts are interpreted to be
volcanic in origin.  Small (less than 20 kilometer or 12 mile diameter)
circular patches in the plains, such as those located in the upper left of
the image, are believed to be small volcanic shields.  Other signs of
volcanism are evident in the bottom center and middle right of the image.
These bright and dark lobes of material are volcanic deposits that have
flowed downhill from source regions not seen in this image.  The bottom
flow complex is the northern part of Mylitta Fluctus, a region of vast
outpourings of lava over 800 kilometers (480 miles) long.  The northern
part of this flow can be seen to surround a few ridges, suggesting that the
ridge belts formed before the eruption of Mylitta.  The placement of the
small (10-15 kilometer or 6-8 mile diameter) double impact crater on top of
the ridges just to the left of Mylitta also supports the idea that the
ridge belts are some of the older features in this region.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38299
                                  7/1/91

Centered at roughly 30 North latitude, 332 East longitude, this Magellan
radar image of part of the southernmost portion of the Lakshmi region of
Venus depicts an area measuring roughly 540 kilometers North-South by 440
kilometers East-West (330 x 270 miles).  The area is dominated by two
distinct features: narrow lineaments and small shield volcanoes.  Much of
the image is covered by long, narrow lineaments, indicating that this
region of plains has been fractured at various scales.  The dominant set of
fractures extends in a bright, broad zone from the northwest corner of the
image down toward the southeast.  The majority of the fractures in this
broad zone are less than 1 kilometer (0.6 miles) wide and less than 20
kilometers (12.5 miles) in length.  These short fractures are often
organized in an en echelon fashion, in which a number of short, offset
fractures oriented in the same direction combine to form what look like
longer, individual lineaments.  Although somewhat fainter, there is a
second set of fractures oriented approximately perpendicular to the bright,
dominant set.  In those areas where the two fracture sets combine, a
gridded pattern results.  In places, the lineament patterns are covered by
individual small shield volcanoes, measuring less than 20 kilometers (12.5
miles) in diameter at the base, or by shield fields, regions on the order
of 100 kilometers (62 miles) in diameter with a concentration of small
shield volcanoes.  The individual volcanoes are occasionally centered on
top of a lineament, suggesting that the emplacement of small shield
volcanoes is structurally controlled.  Since their deposits obscure the
fractures, the majority of the small shield volcanoes shown in the image
are probably younger than the fractures, suggesting that the most recent
stage in the region's geologic development involved active surface
volcanism.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38300
                                  7/16/91

This Magellan image is centered about 24 degrees north latitude and 334
degrees longitude, in the southern Lakshmi Region of Venus.  The image, 600
kilometers (372 miles) in length and 450 kilometers (279 miles) in width,
is a mosaic of 24 orbits.  The image shows plains that have been fractured
in all directions to produce a pattern similar to an alligator's skin.
Several large ridges have bright edges, particularly on their southern
sides.  This may be the result of wind depositing debris at the ridges'
southern edge.  There are two types of wind streaks associated with small
volcanic cones.  The first type of streak occurs in the upper left of the
image.  These radar-bright streaks probably represent depositional material
covering the underlying plains.  The streaks indicate a northeast-southwest
wind flow.  The second type of streak is found in the lower left side of
the image.  These radar-bright streaks are regions of non-deposition or
scouring.  The underlying plains can be seen in the streak but not in the
surrounding area.  The streak's fan shape indicates that the wind direction
varies over several degrees, with a dominant flow towards the south.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38301
                                  7/16/91

This Magellan full resolution mosaic shows a volcanic plains region in
southern Guinevere Planitia, a lowland area 560 kilometers (347 miles) by
540 kilometers (335 miles).  Multiple stages of volcanic activity have
produced overlapping bright (rough-surfaced) and dark (smooth) lava flows
which are especially prominent in the upper left and lower right portions
of the image.  Lavas can be seen as small circular flows surrounding
individual volcanic cones or as extensive flows that have erupted from
volcanic vents and flooded the surrounding terrain.  Sets of bright thin
linear bands that both cut across and are flooded by individual flows are
found in the plains.  A long sinuous trail of bright volcanic cones and
their associated deposits extends southward from the top center of the
image.  Portions of this region show cracks and rifts that have been
flooded by lavas from the cones and surrounding plains.  Near the bottom
center of the image a dark region of numerous lava flows and volcanic cones
occurs among broader and more sinuous ridges and troughs.  This may be a
local zone of crustal extension from which rifts in the crust have allowed
lavas to erupt and flood the area.  The upper right corner of the image
shows a portion of a 500 kilometer (310 mile) long sinuous channel through
which lavas once flowed.  The meandering nature of the channel suggests
that the lavas were very fluid and not as viscous as lavas on Earth.
Sections of the channel also appear to have been obscured by later volcanic
flooding.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38302
                                  7/16/91

This Magellan full resolution mosaic shows a volcanic plains region in
southern Guinevere Planitia, a lowland area on Venus.  The image, centered
at 5 degrees south latitude and 334.8 degrees east longitude, covers an
area 490 kilometers (304 miles) by 540 kilometers (335 miles).  Multiple
stages of volcanic activity have produced overlapping bright (rough-
textured surface) and dark (smooth surface) lava flows which surround
individual volcanic cones and flood older sections of higher ridge and
trough terrain.  Volcanoes, 10-20 kilometers (6-12 miles) across, are shown
in the lower left of the image and are probably composed of more viscous
(sticky) lavas than those flooding the plains.  These structures often have
a central cavity or caldera at their summits (similar to those seen, for
example, in the Hawaiian islands or on the large Martian volcanoes) which
may have formed as magmas feeding the volcano at depth receded into the
crust.  The long thin bright bands in the lower left of the image have
formed from stress within the crust.  They cut through one of the volcanoes
and, in turn, are covered by flows from another volcano.  The heart-shaped
feature to the lower right of that feature is an irregular 15 kilometer (9
mile) wide impact crater showing a dark floor and bright ejecta deposits on
its western and northern flanks.  Impact craters such as this result from
the break-up of meteoroids in the thick Venus atmosphere followed by
multiple impacts from the fragments within a relatively small area.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38302
                                  7/1/91

This image is a mosaic of Magellan orbits 376-402.  It is centered at 5
degrees south latitude, 335 degrees east longitude, in the Navka region of
Venus.  The image is dominated by a broad plains region with scattered
small volcanic constructs and extensional graben or troughs.

The radar-bright and dark patches are volcanic flows overlying, or in some
cases partially buried by other plains materials.  Many of these flow units
contain small volcanic domes.  The reason for such a wide range of radar
brightness variations in these flow units is probably due to differences in
surface roughness and/or compositional differences.

The vertical striping in this mosaic (the so-called "venetian blind
effect") was caused by a two-thirds of a second mismatch between where the
radar data processing system assumed the radar antenna pattern was hitting
the ground and where the radar was actually illuminating the surface.  This
small error was enough to cause the radar processing system to improperly
process data for those orbits, resulting in the banding seen here.  This
timing error appears only in early orbits which were acquired before the
radar instrument's behavior was fully understood.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38303
                                  7/16/91

This Magellan mosaic shows a portion of the Lada Terra highlands on Venus.
The image, centered near 65 degrees south latitude and 14 degrees east
longitude, covers an area about 1900 kilometers (1178 miles) north to south
by about 600 kilometers (372 miles) east to west.  The large complex bright
terrain trending from the lower left to the upper right of the image is
tessera terrain, characterized by multiple sets of complexly intersecting
ridges and troughs.  This region of tessera has been heavily disrupted by
crustal stresses and degraded by later lava flows.  The dark smooth valleys
extending to the northeast area about 15-50 kilometers (9-31 miles) across
and have been filled by lavas.  Near the center of the image within the
tessera are two small semi-circular depressions, separated by about 300
kilometers (186 miles), that may be ancient impact craters heavily modified
by subsequent tessera disruption.  To the north and south of the tessera
lava flows have formed extensive plains regions, flooding the lower
elevations of the edges of Lada Terra.  At the top of the image is the
southern rim of Eithinoha corona, a 500 kilometer (310 mile wide circular
structure surrounded by concentric ridges thought to have formed as hot
magma within the Venus crust migrated toward the surface, bowing up the
crust and producing a smooth interior flooded by volcanic deposits and a
ridged boundary.  Large cracks or rifts are seen extending around the
western edge of the corona and to the south, probably a direct result of
the crustal stresses associated with the formation of the corona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38304
                                  7/26/91

This Magellan full-resolution image of Venus, centered at 35.5 degrees
north, 332 degrees east shows an area in Sedna Planitia with a variety of
morphologies.  The plains have a slightly mottled appearance, indicating
differences in texture, since radar return is dependent on surface
roughness.  The abundant white streaks present in all but the uppermost
part of the image are fractures trending northwest-southeast and south
southwest, bending to the northeast.  Toward the bottom of the image
fractures widen into deep set graben (troughs).  The fractures trending
northwest-southeast cross cut the southwest-northeast fractures implying
that they formed more recently.  The features in the center of the image
with the dappled appearance are a field of shield volcanoes, with diameters
from less than 1 kilometer (.62 miles) to 5 kilometers (3.1 miles).  Shield
volcanos typically have shallow slopes since they are formed from very
fluid lava.  The fact that there are few fractures present in the shield
complex suggests that shields formed subsequent to the episodes of
fracturing.  The rough, bright grey areas along the eastern edge of the
image are intricately deformed terrain called tessera.  The flat-topped
edifice with the star-shaped fracture pattern is a volcanic feature unique
to Venus, although there are relatively few of them.  These edifices,
referred to as "ticks", are distinguished from others by the small ridges
on their slopes radiating outward.  The central part of the edifice is
thought to result from magma rising toward the surface, pushing it upward.
A number of mechanisms have been proposed to explain the existence of
subordinate ridges.  One theory is that they formed from magma reaching
toward the surface along linear weaknesses.  The concentric fractures
around the edifice may have formed from the withdrawal of magma under the
surface and the resulting collapse.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38335
                                  5/23/91

This Magellan full-resolution mosaic of Venus centered at 60.3 degrees
north, 337.5 degrees east shows the northeast portion of Danu Montes
(mountains) where it borders on Lakshmi Planum (plains).  Rising almost two
kilometers (1.2 miles) above the adjacent plains, the mountains appear as
ridges and troughs, implying crustal shortening by compressional forces.
The deep gorges and valleys separate continuous ridges of the folded
terrain, suggesting that an episode of expansion split apart the surface
following the compression.  The largest and most prominent chasm in the
image spans a width of 20 kilometers (12.4 miles) with a length of 75
kilometers (46.5).  There are also round and elongate pits which are
thought to be areas where the surface has collapsed - perhaps where magma
(subsurface molten rock) was emplaced close to the surface.  In some
instances lava flows from these depressions into channels extending more
than 75 kilometers (46.5 miles) out onto the plains.  A possible theory on
the history of this region suggests that after the crust came together
under compression, it heated up, became weaker, and slumped into the
plains.  Some evidence for this can be drawn from analogies on Earth such
as the Himalayas where gravity has forced mountains to split apart under
their own weight.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38338  MGN-46
                                        5/21/91

This image is a composite of 30 orbits recorded by the Magellan spacecraft
in April 1991 superimposed on Pioneer Venus topography (the small grey
triangular wedge in the upper right hand corner of the image).  This image,
with a resolution of 120 meters (370 feet), is centered on the equator at
288 degrees east longitude and shows the complex deformation associated
with faulting in Devana Chasma.  These faults have a relatively uniform
spacing of approximately 5 kilometers (3 miles) and are part of 100 to 180
kilometer (60 to 108 miles) wide zone of deformation.  A group of bright
(rough) lava flows 70 kilometers by 280 kilometers (42 by 168 miles) flow
down the raised west flanks of the Devana Chasma rift valley.  The new
Magellan data reveal remarkable detail and complexity in this deformed
terrain.  Analysis of images from areas such as Devana Chasma is expected
to improve our understanding of the global tectonic forces affecting Venus.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38339  MGN-47
                                        5/21/91

This image is a composite of the first two orbits recorded by the Magellan
spacecraft in August 1990 during the initial in-orbit test of the radar
system.  The data, which are superimposed on Pioneer Venus topography, are
located at the intersection of Devana Chasma and the Phoebe Regio upland.
The image covers a region approximately 525 kilometers by 525 kilometers
(315 x 315 miles), centered at the equator and 288 degrees east longitude.
It includes part of the 150 kilometer (90 miles) wide, 1.0 to 1.5 kilometer
(0.6 to 0.9 miles) deep valley, Devana Chasma.  Devana Chasma consists of
radar bright lineaments, interpreted to be fault scarps, oriented in a
north-northeast direction.  This part of the planet is thought to be an
area where the crust is being stretched and pulled apart producing a rift
valley, similar to the East African rift.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38340  MGN-48
                                        5/21/91

This Magellan radar image shows a region approximately 300 kilometers (180
miles) across, centered on 59 degrees south latitude, 164 degrees east
longitude and located in a vast plain to the south of Aphrodite Terra.  The
data for this image were obtained in January 1991.  The large circular
structure near the center of the image is a corona, approximately 200
kilometers (120 miles) in diameter and provisionally named Aine Corona.
Just north of Aine Corona is one of the flat-topped volcanic constructs
known as "pancake" domes for their shape and flap-jack appearance.  This
pancake dome is about 35 kilometer (21 miles) in diameter and is thought to
have formed by the eruption of an extremely viscous lava.  Another pancake
dome is located inside the western part of the annulus of the corona
fractures.  Complex fracture patterns like the one in the upper right of
the image are often observed in association with coronae and various
volcanic features.  They are thought to form because magma beneath the
surface follows pre-existing fracture patterns.  When eruptions or other
movements of the magma occur, the magma drains from the fractures and the
overlying surface rock collapses.  Other volcanic features associated with
Aine Corona include a set of small domes, each less than 10 kilometers (6
miles) across, located along the southern portion of the annulus of
fractures, and a smooth, flat region in the center of the corona, probably
a relatively young lava flow.  The range of volcanic features associated
with coronae suggests that volcanism plays a significant role in the
formation of coronae.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38341  MGN-49
                                        5/21/91

This image compares the best available views of the crater Golubkina as of
August 1990 (left) and April 1991 (right).  The crater, 34 kilometers (21.1
miles) in diameter, is named for the Russian sculptress Anna Golubkina
(1864-1927).  It is located at about 60.5 degrees north latitude, 287.2
degrees east longitude.  The area shown is approximately 100 kilometers (62
miles) by 215 kilometers (133 miles).  The left image shows Magellan data
from the initial test of the radar system (August 1990), overlain on an
image obtained by the Soviet Venera 15 and 16 spacecraft in 1983-84.  The
data in the right image were obtained by Magellan in April 1991.  The new
image demonstrates the increase in detail obtained by Magellan as compared
with Venera.  Magellan achieved a ten-fold improvement in resolution - 120
meters (400 feet) versus 1.5 kilometers (0.9 miles), for Venera 15 and 16.
The new Magellan data provide the first opportunity to "revisit" areas
previously imaged by the spacecraft.  There is no evidence in these images
for changes in the surface over 243 days.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38346AC
                                        April 12, 1991

This Magellan image shows two large shield volcanoes, Sif (left) and Gula
(right) Montes which are located in the Eistla Region of Venus.  The
superimposed colors represent the planetary topography, or radius, measured
from the center of the planet in kilometers.  The 10-degree grid spacing is
equivalent to approximately 1,050 kilometers (651 miles).  Both volcanoes
are thought to consist of thick accumulations of lava flows.  The flow-like
structure of the most recent lava deposits surrounding Sif Mons is
especially bright in the radar illumination because of the roughness of the
material.  A fracture system, or rift, emanates from the southeastern flank
of Gula Mons and extends several hundred kilometers beyond the edge of the
frame.
                          MAGELLAN PROJECT OFFICE

                                 P-38346BC
                                  4/12/91

A shaded-relief perspective view of Venus prepared from Magellan data, that
shows two large shield volcanoes, Sif (left) and Gula (right), located in
the Eistla Region.  The superimposed colors represent the radiothermal
emissivity as given by the scale at right.  Emissivity is a measure of the
surface's ability to radiate energy, and depends primarily on the
material's electrical properties.  The 5-degree grid spacing is equivalent
to 528 kilometers (328 miles).  Both volcanoes are thought to consist of
thick accumulations of lava flows.  Note the relatively low values of
emissivity associated with the summits, a property often found at higher
elevations on Venus that is possibly the result of a change in the
mineralogy as the ambient temperature and pressure drop.  A fracture
system, or rift, emanates from the southeastern flank of Gula Mons and
extends several hundred kilometers beyond the edge of the frame.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                 P-38346CC
                                  4/12/91

A shaded-relief perspective view of a region surrounding the 10-km-high
Maxwell Montes on Venus, prepared from Magellan data.  The superimposed
colors represent the radiothermal emissivity of the region as given in the
scale at right.  Emissivity is a measure of the surface's ability to
radiate energy, and depends primarily on the material's electrical
properties.  The higher elevations of Maxwell display some of the lowest
values of emissivity found on the planet; these low values probably result
from changes in the surface mineralogy of volcanic flows when exposed for
long periods of time to the lower ambient temperatures and pressures found
at high altitudes.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38359  MGN-50
                                        5/21/91

This image compares Magellan data acquired in August 1990 during the
initial test of the radar system (black and white insets), with data
acquired by the spacecraft in April 1991 (color background).

The area is in the southern hemisphere of Venus, and represents an area
about 540 kilometers (335 miles) on a side, centered on latitude 35 degrees
south and longitude 294 degrees east.  The Magellan radar illuminates the
surface from the left.

The northern and eastern parts of the area consist of plains, which appear
moderately-dark to dark on the radar image because they are relatively
smooth at a scale comparable to the wavelength of the radar, 12.5
centimeters (about 5 inches).  The bright terrain in the southwestern part
of the image is about 500 to 700 meters (1640 to 2300 feet) higher than the
plains; it is characterized by abundant faults and fractures, which appear
as straight to gently curved bright lines.  Many of these linear features
are large enough to infer that they are graben, which are troughs bounded
on both sides by faults.  However, many of them are too narrow to determine
if they are faults or simply fractures that have roughened the surface.
This elevated faulted and fractured region is part of a large east-west
elongated ridge mapped by the Pioneer Venus radar altimeter; the portion
shown here is about midway between Themis Regio and Tefnut Mons.

The plains are probably underlain by volcanic lavas.  The various shades
indicate that minor differences in surface roughness are present, and these
may be used to map out the distribution of different lavas.  The small,
bright patches on the plains represent places where the lava surfaces are
relatively rough.  Just left of the center of the image is a sharply
defined volcanic crater about 15 kilometers (9.3 miles) in diameter.
Immediately north of this crater are numerous round spots about 2-4
kilometers (1-2 miles) across that are small volcanic domes.  The low-
resolution strip along the eastern edge of this image represents earth-
based Arecibo data at a resolution about 20 times coarser than that of the
Magellan data.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38360  MGN-51
                                        5/21/91

This false-color Magellan image shows the volcano Sapas Mons, located in
the broad equatorial rise known as Atla Regio (8 degrees north latitude,
188 degrees east longitude).  The area shown is approximately 650
kilometers (400 miles) on a side.  The volcano itself is about 400
kilometers (250 miles) across and rises 1.5 kilometers (0.9 miles) above
the local terrain.  It is about 4.5 km above the mean planetary radius.
The flanks of the volcano are composed of numerous overlapping lava flows.
The dark flows on the lower right are thought to be smoother than the
brighter flows near the central part of the volcano.  Many of the flows
appear to have erupted along the flanks of the volcano, rather than from
the summit.  This type of flank eruption is common on large volcanoes on
the Earth, such as the Hawaiian volcanoes.  The summit area consists of a
pair of flat-topped mesas, whose smooth tops give a relatively dark
appearance in the radar image.  Also seen near the summit are groups of
pits, some as large as 1 kilometer (0.6 miles) across.  These are thought
to have formed when underground chambers of magma were drained through
other subsurface tubes, leading to a collapse at the surface.  A 20-
kilometer (12.5-mile) diameter impact crater northeast of the volcano is
partially buried by the lava flows.  Little was known about the Atla Regio
rise prior to Magellan.  The new data, taken in February 1991, show the
region to be composed of at least five large volcanic edifices such as
Sapas Mons, which are commonly linked by complex systems of fractures or
rift zones.  By analogy with similar features on the Earth, Atla Regio is
thought to result from upwellings of large volumes of molten rock from the
interior of Venus known as "hot spots."
                          MAGELLAN PROJECT OFFICE

                                  P-38387
                                  6/5/91

Many of the impact craters of Venus revealed by Magellan have
characteristics unlike craters on any other planetary body.  This 30-
kilometer (18.6-mile) diameter crater, named Adivar crater for the Turkish
educator and author Halide Adivar (1883-1964), is located just north of the
western Aphrodite highland (9 degrees north latitude, 76 degrees east
longitude).  Surrounding the crater rim is ejected material which appears
bright in the radar image due to the presence of rough fractured rock.  A
much broader area has also been affected by the impact, particularly to the
west of the crater.  Radar-bright materials, including a jet-like streak
just west of the crater, extend for over 500 kilometers (310 miles) across
the surrounding plains.  A darker streak, in a horseshoe or paraboloidal
shape, surrounds the bright area.  Radar-dark (i.e., smooth) paraboloidal
streaks were observed around craters in earlier Magellan images, but this
is a rare bright crater streak.  These unusual streaks, seen only on Venus,
are believed to result from the interaction of crater materials (the
meteoroid, ejecta, or both) and high-speed winds in the upper atmosphere.
The precise mechanism that produces the streaks is poorly understood, but
it is clear that the dense atmosphere of Venus plays an important role in
the cratering process.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38388
                                  6/5/91

This Magellan full resolution mosaic, centered at 12.3 north latitude, 8.3
east longitude, shows an area 160 kilometers (96 miles) by 250 kilometers
(150 miles) in the Eistla region of Venus.  The prominent circular features
are volcanic domes, 65 kilometers (39 miles) in diameter with broad flat
tops less than 1 kilometer (.6 mile) in height.  Sometimes referred to as
"pancake" domes, they represent a unique category of volcanic extrusions on
Venus formed from viscous (sticky) lava.  The cracks and pits commonly
found in these features result from cooling and the withdrawal of lava.  A
less viscous flow was emitted from the northeastern dome toward the other
large dome in the southwest corner of the image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38434
                                  6/14/91

This Magellan image shows a tectonically disrupted zone in the Thetis
region of Venus.  The image, centered on 15 degrees south latitude, 163
east longitude, is roughly 1,600 kilometers (992 miles) by 1,850 kilometers
(1,147 miles).  The bright arcuate features, which consist of numerous
closely-spaced ridges and troughs, mark the locations of exceptionally deep
chasmata (canyons).  The chasmata commonly terminate at or wrap around
circular corona structures, such as the 500 kilometers (310 miles) diameter
feature in the lower right.  The eastern portion of Dali Chasma extends
from the left edge of the image and terminates at a corona-like feature
near the center of the image.  Dali Chasma is up to 4 kilometers (3 miles)
deep in the area pictured.  Diana Chasma, with comparable depths, extends
from the lower left to the lower right of the image.  These chasmata are
part of the Aphrodite Terra equatorial highland, which is approximately
16,000 kilometers (9,920 miles) in length.  The dramatic topography of the
chasmata, and their association with the large Aphrodite structure, suggest
that they may hold keys to understanding the global tectonic framework of
Venus.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38449
                                  6/14/91

This map shows the topography of a portion of the Thetis region of Venus,
using data acquired by the Magellan altimetry instrument.  Colors represent
the planetary radius, measured in kilometers.  The 10-degree grid spacing
is equivalent to approximately 1050 kilometers (651 miles).  The east-west
trending troughs near the center of the map are Diana and Dali Chasmata.
These valleys are up to 4 kilometers (3 miles) deep in places.  Slopes as
steep as 25 degrees, extending over several kilometers, are found at the
edges of the valleys.  The existence of such dramatic relief suggests that
active tectonic forces may be dynamically supporting the topography.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38450
                                  6/14/91

This Magellan image shows part of the highland Ovda Regio.  The
superimposed colors represent the planetary radius (topography), measured
in kilometers.  The 10-degree grid spacing is equivalent to approximately
1,050 kilometers (651 miles).  A thick flow of possibly viscous lava
extends about 160 kilometers (99 miles) in the east-west direction near the
center of the image.  The topography indicates that the central region of
the flow now lies nearly 1 kilometer (0.62 mile) lower than the edges of
the flow.  This may be the result of subsidence of the central area
following the emplacement of the lava flow.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38451
                                  6/14/91

This image shows false-color representation of the surface relief of Venus
between longitudes 100 degrees and 190 degrees east, as measured by the
altimeter aboard the Magellan spacecraft.  The distance from top to bottom
(pole-to-pole) is 19,000 kilometers (11,780 miles).  Colors represent
variations in planetary radius, measured in kilometers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38452
                                  6/14/91

A perspective view of the topography Dali (to left) and Diana (to right)
towards the southwest at 15 degrees south latitude, just to the east of
Aphrodite Terra on Venus.  Vertical exaggeration is about twenty-to-one.
These valleys are 4 kilometers (3 miles) deep and about 65 kilometers (40
miles) wide, with walls sloping down at angles as steep as 25 degrees.  The
data were obtained by Magellan's altimetry.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38471
                                  6/19/91

This large lava-flow field, which is about 140 kilometers (87 miles) wide
and 300 kilometers (186 miles) long, was deposited on the rugged uplands of
Ovda Regio.  Subsequently, dark smooth appearing materials were deposited
atop the southeastern margins of the lavas and the rugged uplands.  Finger-
like lobes of lavas extend from the margins of the field in all directions,
but generally away from the center of the field and the now-hidden source
of the lavas.  Unlike most lava flows on Venus, which are thin, some lobes
of these lavas are estimated to be near 200 meters (660 feet) thick.
Lobate flows on Earth that are this thick are evolved, silica-rich lavas
such as trachytes and rhyolites; basalt flows in Hawaii are much thinner
than the Venusian lobes.  Compression of the upper parts of the lavas
during flow has produced concentric ridge and trough segments, also called
pressure ridges, on the surface of the flow.  The Magellan altimeter shows
that the surface of the flow is spoon-shaped and lower near the west-
central part (left) than elsewhere.  The reason for this shape is unclear,
but up-welling and subsidence of lava and faulting are possibilities.
There is evidence that substances such as pyrite, magnetite, or other
conductors are present at the surface of the flow.  These substances
suggest exciting possibilities for the composition of the lava flow field
or some other processes unrelated to the flow.  Magellan scientists are
pursuing the geological implications of this flow field.  Center of lava
flow field is at 6.0 degrees south and 95.5 degrees east.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38515
                                  7/1/91

This Magellan radar mosaic shows a portion of the Lada Terra highlands on
Venus.  The image, centered near 60 degrees south latitude and 15 degrees
east longitude, covers an area about 1600 kilometers (970 miles) north-
south by about 1840 kilometers (1100 miles) east-west.  The large circular
feature in the north-west of the image is the 500 kilometer (300 mile)
diameter Eithinoha corona.  Corona are thought to have formed as hot magma
within the Venus crust migrates towards the surface, causing up-bowing of
the crust and formation of a ridged boundary surrounding a central region
of volcanism.  Several lava flows and small shields can be seen in the
center of this structure.  The bright lines extending away from the corona
are cracks and rifts that are probably a direct result of the crustal
stresses associated with the formation of the corona.  The arch in the
lower left of the image is the boundary of another large corona.  Extensive
volcanism has also occurred in the plains and gives them a patchy or
mottled appearance.  This plains-forming volcanism has flooded some
surrounding higher material, such as the bright patches of tessera east and
southeast of Eithinoha corona.  Tessera consists of multiple sets of
complex intersecting ridges and troughs and often forms large (100's of
kilometers wide) continuous patches of elevated terrain.  In this case,
however, the tessera has been flooded and degraded by volcanic activity,
suggesting that the tessera is one of the older features in this region.
The narrow channel that can just be seen in the lower central portion of
the image was probably formed by the flow of lava from within the tessera
out to the surrounding plains to the southwest; lobate lava deposits can be
seen at the end of the channel.  Two well-preserved, 30-40 kilometer (18-24
mile) diameter impact craters are found in the north central plains and two
small circular features in the south central tessera may be degraded impact
craters.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38515  MGN-58
                                        7/26/91

This Magellan radar mosaic shows a portion of the Lada Terra highlands on
Venus.  The image, centered near 60 degrees south latitude and 15 degrees
east longitude, covers an area about 1600 kilometers (970 miles) north-
south by about 1,840 kilometers (1,100 miles) east-west.  The large
circular feature in the north-west of the image is the 500 kilometer (300
mile) diameter Eithinoha corona.  Coronae are thought to have formed as hot
magma within the Venus crust migrates towards the surface, causing up-
bowing of the crust and formation of a ridged boundary surrounding a
central region of volcanism.  Several lava flows and small shields can be
seen in the center of this structure.  The bright lines extending away from
the corona are cracks and rifts that are probably a direct result of the
crustal stresses associated with the formation of the corona.  The arch in
the lower left of the image is the boundary of another large corona.
Extensive volcanism has also occurred in the plains and gives them a patchy
or mottled appearance.  This plains-forming volcanism has flooded some
surrounding higher material, such as the bright patches of tessera east and
southeast of Eithinoha corona.  Tessera consists of multiple sets of
complex intersecting ridges and troughs and often forms large (100's of
kilometers wide) continuous patches of elevated terrain.  In this case,
however, the tessera has been flooded and degraded by volcanic activity,
suggesting that the tessera is one of the older features in this region.
The narrow channel that can just be seen in the lower central portion of
the image was probably formed by the flow of lava from within the tessera
out to the surrounding plains to the southwest; lobate lava deposits can be
seen at the end of the channel.  Two well-preserved, 30-40 kilometer (18-24
mile) diameter impact craters are found in the north central plains and two
small circular features in the south central tessera may be degraded impact
craters.
                          MAGELLAN PROJECT OFFICE

                                  P-38547
                                  4/12/91

Topographic relief of western Eistla Regio, showing the volcanic mountains,
Sif (the red dot at left center) and Gula (the gray dot at right center).
The superimposed colors represent the altitude of the surface features,
measured from the center of the planet in kilometers (see scale at right).
The 10-degree grid spacing is equivalent to 1,056 kilometers (656 miles).
Both volcanoes are thought to consist of thick accumulations of lava flows.
A fracture system, or rift, emanates from the southeastern flank of Gula
Mons and extends several hundred kilometers nearly to the edge of the
frame.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38548
                                  7/1/91

This is a Magellan radar mosaic of a region approximately 1300 kilometers
(806 miles) across, centered at 21 degrees north latitude, 1 degree east
longitude.  Left of center is the radar-bright elongated summit of Gula
Mons, a 1.8 kilometer (1.1 mile)-high volcano.  Radiating outward in all
directions from the summit is a system of lava flows, most of which are
several hundred kilometers (up to about 600 miles) long.  Though many of
these flows appear bright in the radar image, dark flows are also present.
This variability in radar brightness is largely due to differences in
surface roughness from one flow to another.  Dark flows are smoother than
bright flows.  The darker flows may be similar to terrestrial pahoehoe lava
flows, whereas, the brighter flows are likely similar to terrestrial aa
flows, which have a very rough, blocky surface texture.  Trending
southeastward from Gula Mons is a system of radar-bright irregular
lineaments.  This is the northwest end of Eistla Regio, a broad system of
fractures and fault scarps that extends for approximately 6000 kilometers
(3720 miles) eastward toward Aphrodite Terra.  The individual scarps appear
bright in the radar both because they are rough textured and because they
face in the general direction of the incident radar beam (similar to a sun-
facing slope appearing bright in visible light).  Gula Mons is surrounded
by plains that are likely volcanic flood plains.  At least five impact
craters are present in this scene.  One of these, at right center, is
associated with a roughly parabolic shaped dark region.  The crater lies
near the apex of the parabola which widens and fades to the west.
Approximately 10 percent of the craters on Venus are associated with this
parabolic feature which, in all cases, widens westward in the direction the
wind blows in Venus' upper atmosphere.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38605
                                  8/2/91

This full resolution mosaicked image covers an area of approximately 100
kilometers by 120 kilometers (62 by 74 miles) and is located in the Lakshmi
region of Venus at 47 degrees north latitude and 334 east longitude.

Due to the dense Venusian atmosphere, primary impact craters of less than a
3 kilometer (2 mile) diameter are nonexistent.  The dark circular region
and associated central bright feature in this image are thought to be the
remnants of a meteoroid smaller than the size necessary to create an impact
crater entering the atmosphere at a low velocity (approximately 350
meters/second.)  The central bright feature appears to be a cluster of
small secondary impacts, ejecta and debris from the original meteor that
broke up in the atmosphere.  Even though most of the meteorite did not hit
the surface, the atmospheric shock wave could be great enough to modify the
surrounding region.  One explanation for this radar dark circular
formation, called dark margins, could be that the shock wave was energetic
enough to pulverize the surface (smooth surfaces generally appear radar
dark.)  Another explanation is that the surface could be blanketed by a
fine material that was formed by the original meteor's breakup through the
atmosphere.  More than half of the impact craters on Venus have associated
dark margins, and most of these are prominently located left of center of
the crater.  This is another effect which could be caused by the dense
atmosphere of Venus.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38606
                                  8/2/91

This Magellan mosaic covers an area of approximately 228 kilometers by 228
kilometers (141 by 141 miles).  It is centered at 9.3 degrees north
latitude, 357.8 degrees east longitude in the Navka region.  The radar
illumination is from the left.  The image shows a cluster of impact craters
whose ejecta is distributed in a butterfly pattern rather than radially out
from the craters.  The impacting object probably broke up during its
passage through the atmosphere causing the multiple craters.  The
asymmetrical distribution of ejecta is indicative of an impact from an
oblique angle.  The cluster is located in a fractured plain with radar
bright lineaments intersecting in several directions.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38607
                                  8/2/91

This full resolution radar mosaic from Magellan centered at 15 degrees
north latitude, 351 degrees east latitude, contains an impact crater
approximately 25 kilometers (16 miles) in diameter.  The crater Cunitz
possesses a radar-bright ejecta blanket and non-radial flow-like ejecta
indicative of flow of a low-viscosity material.  On the periphery of the
radar-bright ejecta blanket "dark margins" with low backscatter values are
observed.  The crater floor contains relatively smooth material with
numerous linear fractures reminiscent of lunar mare wrinkle ridges.  The
impact crater occurs in an area of highly fractured plains and apparently
postdates fracturing as evidenced by the manner in which the ejecta
material is directed by the fractures.  The principle fractures trend
roughly east-west and intersect nearly orthogonal with shorter fractures
creating a polygonal pattern.  Fainter troughs trend nearly north-south and
are probably the youngest fractures.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38608
                                  8/2/91

A portion of Lavinia Planitia (30 degrees south latitude, 338 degrees east
longitude) is displayed in this image of the surface of Venus.  The image
covers a region approximately 75 kilometers by 135 kilometers (47 by 84
miles).  Three dome shaped features, 8 to 15 kilometers (5 to 9 miles) in
diameter, are seen in the southern part of the region.  Analogues to these
dome shaped features can be found in a number of different environments on
Earth, such as Long Valley, California, and Valles, New Mexico.  Tens of
kilometers north of these domes is a small conical volcano, 8 kilometers (5
miles) in diameter and several hundred meters high.  The 3 kilometer (2
mile) summit pit of the volcano suggests explosive eruptions, tectonic
activity, or collapse of the summit.  The volcanoes are surrounded by an
abundance of lineaments and fractures.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38609
                                  8/2/91

Data for this image were recorded by Magellan during the first cycle of
Venus orbits in September 1990 using Magellan's synthetic aperture radar
(SAR).  North is towards the top of the image, and radar illumination is
from the left at an incidence angle of 38 degrees.  The image is centered
at 20.2 degrees south latitude and 338.7 degrees east longitude, west of
Alpha Regio in the Navka region of Venus, and covers a section of the
surface approximately 150 kilometers (93 miles) in width by 200 kilometers
(124 miles) in length.  Two circular areas with low radar backscatter
cross-sections can be seen in the image, and are most likely due to
meteoroid-atmosphere interaction.

Large, radar-dark regions like the ones in the image, often called "dark
margins," have been observed in association with about half of the impact
craters on Venus, and it is speculated that such regions are the product of
atmospheric shock waves from impactors.  A second hypothesis attributes the
dark regions to fine deposits of material created on impact or by ablation
during atmospheric transit.  The dark margin in the southern half of the
image appears to surround a small, irregular impact crater or multiple
crater, though the feature to the north does not.  This suggests that the
latter was due to a smaller meteoroid, one destroyed during transit, but
large enough to create a shock or pressure wave able to deform the surface.
Both radar-dark areas are about 50 km (31 miles) in diameter.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38610
                                  8/2/91

This Magellan image, located in the Navka region of Venus, covers an area
approximately 212 kilometers (131 miles) wide and 405 kilometers (251
miles) long.  The large circular structure, approximately 50 kilometers (31
miles) across, centered at 16 degrees south latitude and 352 degrees east
longitude (about 1500 kilometers [930 miles] northwest of Alpha Regio)
probably resulted from an upwelling of magma.  There is an abundance of
lineaments associated with this structure arranged radially around the rim
while, at greater distances, the fractures are generally north-south
trending.  These fractures are thought to be the surface expression of
numerous shallowly placed dikes, the orientation of which is controlled
near the structure by stress associated with the magma chamber.  Further
away from the structure, the fractures may be controlled by a larger
regional stress field.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38611
                                  7/16/91

These radar images show an identical area on Venus (centered at 110 degrees
longitude and 64 degrees north latitude) as imaged by the U.S. Magellan
spacecraft in 1991 (left) and the U.S.S.R.  Venera 15/16 spacecraft in the
early 1980's (right).  Illumination is from the left (or west) in the
Magellan image (left) and from the right (or east) in the Venera image
(right).  Differences in apparent shading in the images are due to
differences in the two radar imaging systems.  Prior to Magellan, the
Venera 15/16 data was the best available for scientists studying Venus.
Much greater detail is visible in the Magellan image owing to the greater
resolution of the Magellan radar system.  In the area seen here,
approximately 200 small volcanoes, ranging in diameter from 2 to 12
kilometers (1.2 to 7.4 miles) can be identified.  These volcanoes were
first identified as small hills in Venera 15/16 images and were predicted
to be shield-type volcanoes constructed mainly from eruptions of fluid lava
flows similar to those that produce the Hawaiian Islands and sea floor
volcanoes - a prediction that was confirmed by Magellan.  These small
shield-type volcanoes are the most abundant geologic feature on the surface
of Venus, believed to number in the hundreds of thousands, perhaps
millions, and are important evidence in understanding the geologic
evolution of the planet.  The only other planet in our Solar System with
this large number of volcanoes is Earth.  Clearly visible in the Magellan
image are details of volcano morphology, such as variation in slope, the
occurrence and size range of summit craters, and geologic age relationships
between adjacent volcanoes, as well as additional volcanoes that were not
identifiable in the Venera image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38665
                                  7/26/91

This mosaic is a composite of three pre-Magellan data sets: Arecibo radar
images, Pioneer Venus radar images, and Pioneer Venus altimetry and shows
the area imaged by Magellan during its first eight weeks of mapping.  The
curved dark lines represent gaps in the Magellan data that occurred due to
Deep Space Network (DSN) outages and spacecraft pointing errors.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38690
                                  8/2/91

This Magellan image centered near 9.6 degrees north latitude, 189.5 degrees
east longitude of an area 140 kilometers (87 miles) by 110 kilometers (68
miles) covers part of the eastern flank of the volcano Sapas Mons on the
western edge of Atla Regio.  The bright lobate features along the southern
and the western part of the image, oriented in northeast to southwest
directions, are lava flows that are rough at the 12.6 centimeter wavelength
of the radar.  These flows range in width from 5 kilometers to 25
kilometers (3 to 16 miles) with lengths of 50 kilometers to 100 kilometers
(31 to 62 miles), extending off the area shown here.  Additional radar-dark
(smooth) flows are also present.  The radar-bright linear structures in the
northwest part of the image are interpreted to be faults and fractures
possibly associated with the emplacement of magma in the subsurface.
Located near the center of the image is a 20 kilometer- (12 mile-) diameter
impact crater.  This crater is superimposed on a northeast/southwest
trending fracture while the southern part of the crater's ejecta blanket is
covered by a 6 kilometer- (4 mile-) wide radar-bright lava flow.  These
relations indicate that the crater post dates an episode of fracturing and
is older than the lava flows covering its southern edge.  This is one of
only a few places on Venus in which an impact crater is seen to be covered
by volcanic deposits.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38691
                                  8/2/91

This Magellan image shows an impact crater in the central Eistla Region of
the equatorial highlands of Venus.  It is centered at 15 degrees north
latitude and 5 degrees east longitude.  The image is 76.8 kilometers (48
miles) wide.  The crater is slightly irregular in planform and
approximately 6 kilometers (4 miles) in diameter.  The walls appear
terraced.  Five or six lobes of radar-bright ejecta radiate up to 13.2
kilometers (8 miles) from the crater rim.  These lobes are up to 3.5
kilometers (2 miles) in width and form a "starfish" pattern against the
underlying radar-dark plains.  The asymmetric pattern of the ejecta
suggests the angle of impact was oblique.  The alignment of two of the
ejecta lobes along fractures in the underlying plains is apparently
coincidental.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38707
                                  8/2/91

This Magellan image is centered about 3.2 degrees north latitude, 194.9
degrees longitude in the eastern Ovda region of Venus.  The image, which is
90 km (56 miles) in width and 80 km (50 miles) in length, shows some small
volcanic domes on the flank of the volcano Maat.  The bright flows to the
east are most likely rough lava flows while the darker flows to the west
are probably smoother flows.  The dark flows do show some roughness,
however, as can be seen by the structure in the flows to the southwest.
These dark flows also have some debris that has been deposited on top of
the flows.  The debris may be fine material from the surrounding plains on
top of the flow by wind or it may be ash from the volcano.

Small volcanic domes are very common features on the surface of Venus,
indicating that there has been much volcanic activity on the surface.
Assuming that the central volcanic cone is symmetrical in shape and knowing
the length of the cone's side and the incidence angle, radar foreshortening
yields a height and slope of 688 meters and 8.2 degrees, respectively for
the cone.  These values are similar to heights and slopes of some volcanic
cones on the Earth.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38720  MGN-76
                                        October 29, 1991

A portion of Western Eistla Regio is displayed in this three-dimensional
perspective view of the surface of Venus.  The viewpoint is located 1,310
kilometers (812 miles) southwest of Gula Mons at an elevation of 0.78
kilometers (0.48 mile).  The view is to the northeast with Gula Mons
appearing on the horizon.  Gula Mons, a 3 kilometer (1.86 mile) high
volcano, is located at approximately 22 degrees north latitude, 359 degrees
east longitude.  The impact crater Cunitz, named for the astronomer and
mathematician Maria Cunitz, is visible in the center of the image.  The
crater is 48.5 kilometers (30 miles) in diameter and is 215 kilometers (133
miles) from the viewer's position.  Magellan synthetic aperture radar data
is combined with radar altimetry to develop a three-dimensional map of the
surface.  Rays cast in a computer intersect the surface to create a three-
dimensional perspective view.  Simulated color and a digital elevation map
developed by the U.S. Geological Survey, are used to enhance small-scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced at the JPL
Multimission Image Processing Laboratory and is a single frame from a video
released at the March 5, 1991, JPL news conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38721  MGN-77
                                        October 29, 1991

Gula Mons is displayed in this computer-simulated view of the surface of
Venus.  The viewpoint is located 110 kilometers (68 miles) southwest of
Gula Mons at the same elevation as the summit, 3 kilometers (1.9 miles)
above Eistla Regio.  Lava flows extend for hundreds of kilometers across
the fractured plains.  The view is to the northeast with Gula Mons
appearing at the center of the image.  Gula Mons, a 3 kilometer (1.9 mile)
high volcano, is located at approximately 22 degrees north latitude, 359
degrees east longitude in western Eistla Regio.  Magellan synthetic
aperture radar data is combined with radar altimetry to produce a three-
dimensional map of the surface.  Rays cast in a computer intersect the
surface to create a three-dimensional perspective view.  Simulated color
and a digital elevation map developed by the U.S. Geological Survey are
used to enhance small-scale structure.  The simulated hues are based on
color images recorded by the Soviet Venera 13 and 14 spacecraft.  The image
was produced by the JPL Multimission Image Processing Laboratory and is a
single frame from a video released at the March 5, 1991, JPL news
conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38722  MGN-74
                                        October 21, 1991

Sif Mons is displayed in this computer-simulated view of the surface of
Venus.  The viewpoint is located 360 kilometers (223 miles) north of Sif
Mons at a height of 7.5 kilometers (4.7 miles) above the lava flows.  Lava
flows extend for hundreds of kilometers across the fractured plains shown
in the foreground to the base of Sif Mons.  The view is to the south.  Sif
Mons, a volcano with a diameter of 300 kilometers (186 miles) and a height
of 2 kilometers (1.2 miles), appears in the upper half of the image.
Magellan synthetic aperture radar data is combined with radar altimetry to
produce a three-dimensional map of the surface.  Rays, cast in a computer,
intersect the surface to create a three-dimensional perspective view.
Simulated color and a digital elevation map developed by the U.S.
Geological Survey are used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced at the JPL Multimission Image
Processing Laboratory and is a single frame from a video released at the
March 5, 1991, JPL news conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38723  MGN-73
                                        October 21, 1991

A corona is displayed in this computer-simulated view of the surface of
Venus.  The viewpoint is located 150 kilometers (93 miles) north of Gula
Mons at a height of 1.6 kilometers (1 mile) above the corona.  The corona
has a diameter of 97 kilometers (60 miles).  The proposed name for the
corona is Idem-Kuva, a Finno-Ugraic harvest spirit.  Lava Flows extend for
hundreds of kilometers across the fractured plains shown in the background.
The viewpoint is to the north with Gula Mons to the south.  Magellan
synthetic aperture radar data is combined with radar altimetry to produce a
three-dimensional map of the surface.  Rays, cast in a computer, intersect
the surface to create a three-dimensional perspective view.  Simulated
color and a digital elevation map developed by the U.S. Geological Survey
are used to enhance small-scale structure.  The simulated hues are based on
color images recorded by the Soviet Venera 13 and 14 spacecraft.  The image
was produced at the JPL Multimission Image Processing Laboratory and is a
single frame from a video released at the March 5, 1991, JPL news
conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38724  MGN-72
                                        September 27, 1991

A portion of Western Eistla Regio is displayed in this three-dimensional
perspective view of the surface of Venus.  The viewpoint is located 1,100
kilometers (682 miles) northeast of Gula Mons at an elevation of 7.5
kilometers (4.6 miles).  Lava flows extend for hundreds of kilometers
across the fractured plains shown in the foreground, to the base of Gula
Mons.  We are looking to the southwest with Gula Mons appearing at the left
just below the horizon.  Gula Mons, a 3 kilometer (1.86 mile) high volcano,
is located at approximately 22 degrees north latitude, 359 degrees east
longitude.  Sif Mons, a volcano with a diameter of 300 kilometers (180
miles) and a height of 2 kilometers (1.2 miles), appears to the right of
Gula Mons.  The distance between Sif Mons and Gula Mons is approximately
730 kilometers (453 miles).  Magellan synthetic aperture radar data is
combined with radar altimetry to develop a three-dimensional map of the
surface.  Ray tracing - rays as if from a light source are cast in a
computer to intersect the surface - simulate a perspective view.  Simulated
color and a digital elevation map developed by Randy Kirk of the U.S.
Geological Survey, are used to enhance small scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced at the JPL Multimission Image
Processing Laboratory by Eric De Jong, Jeff Hall, and Myche McAuley, and is
a single frame a video released at a March 5, 1991, JPL news conference.
                          MAGELLAN PROJECT OFFICE

                                  P-38741
                                  8/12/91

This remarkable "half crater" is located in the rift between Rhea and Theia
Montes in Beta Regio.  Radar illumination is from the left.  The as yet
unnamed crater is 37 (23 miles) kilometers in diameter and is located at
latitude 29.91 degrees north, longitude 282.9 degrees east.  It has been
cut by many fractures or faults since it was formed by the impact of a
large asteroid.  The eastern half of the crater has been completely
destroyed during the formation of a fault-valley that is up to 20
kilometers (12 miles) wide and apparently quite deep.

A north-south profile through the very center of this crater is visible as
a result of the downdropping and removal of the eastern half of the crater.
This "profile view" gives a third dimension to the crater.  Thus it will be
beneficial to "illuminate" this area from the opposite side (right-looking)
with the Magellan SAR during a later mapping cycle, permitting an even more
detailed view of the geologic structure of this feature.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38809
                                  8/12/91

This full-resolution radar mosaic from Magellan centered at 13.5 degrees
South latitude, 161 degrees longitude shows a 5.5 kilometer (3.3 mile) high
scarp north of Dali Chasma, in the Thetis Region of Venus.

The bright region in the bottom one-third of the mosaic, is elevated above
the darker material to the north (and separated from it by the scarp).  At
least 3 landslides from the scarp can be identified in the mosaic, along
with the head scarps from which they came.  These are the hummocky surfaces
at center, just left of center, and just above right center.  These
landslides range up to 30 kilometers (18 miles) from the base of the scarp.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-38810
                                  8/12/91

The comet-like tail trending northeast from this volcanic edifice is a
relatively radar-bright deposit.  The volcano, whose basal diameter is 5
kilometers (about 3 miles), is a local topographic high that has slowed
down northeast trending winds enough to cause deposition of this material.
The streak is 35 kilometers (about 22 miles) long and 10 kilometers (about
6 miles) wide.  The volcano is located at the western end of Parga Chasma
at 9.4 degrees south latitude, 247.5 degrees east longitude.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38811
                                  8/12/91

Two unusual volcanic domes are shown in this Magellan full-resolution
mosaicked image.  The image covers an area 180 by 240 kilometers (120 by
160 miles) centered at 18.1 degrees north latitude, 303.52 degrees east
longitude, just east of Beta Regio.  The dome in the south center of the
image is about 45 kilometers (30 miles) across, with a 20 kilometer (13
mile) caldera, or volcanic collapse crater, in the center.  The dome in the
northwest corner of the image is about 30 kilometers (20 miles) across with
a small (5 kilometer or 3 mile) summit crater; the very bright radar return
from the western flank of this dome indicates that it has steep slopes.
The flanks of these volcanoes display prominent gullies which may have been
formed by slumping of surface material or thermal erosion by lava flows.
Variation in the brightness within the surrounding plains show the extent
of lava flows which originated at these volcanoes.  Arcuate fractures
surrounding the southern edifice indicate that there has been subsidence
(down-warping) of the dome following eruptive activity.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38827
                                  8/12/91

This full-resolution radar mosaic from Magellan at 52 degrees north
latitude, 170 degrees east longitude, shows a 94 kilometer (56 mile)
segment of the longest channel discovered on Venus to date.  The channel is
approximately 1.8 kilometers (1.1 miles) wide.  At over 7000 kilometers
(4200 miles) long, it is at least several hundred kilometers longer than
the Nile River, Earth's longest river; thus, making it the longest known
channel in the solar system.  Both ends of the channel are obscured,
however, so its original length is unknown.

This channel was initially discovered by the Soviet Venera 15-16 orbiters,
which, in spite of their 1 kilometer resolution, detected over 1000
kilometers of the channel.  These channel-like features are common on the
plains of Venus.  In some places they appear to have been formed by lava
which may have melted or eroded a path over the plains' surface.  They
resemble terrestrial meandering rivers superficially.  Most are 1-3
kilometers (.6 to 2 miles) wide, though one degraded channel is 12
kilometers (7.4 miles) wide.  They often exhibit meanders, cutoff oxbows,
and abandoned channel segments, though they are not as tightly sinuous as
terrestrial rivers.  Most are partly buried by younger lava plains, making
their sources difficult to identify.  A few have terminal deposits, vast
radar-dark plains units associated with them, suggesting large flow
volumes.  These channels appear to be older than other channel types, as
they are crossed by fractures and wrinkle ridges, and are often buried by
other volcanic materials.  In addition, they appear to run both upslope and
downslope, suggesting that the plains formed and were later warped by
regional tectonism.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  9110
                          MAGELLAN PROJECT OFFICE

                                  P-38828
                                  8/12/91

This full-resolution radar mosaic from Magellan at 51 degrees north
latitude, 168 degrees east longitude, shows a 140 kilometer (84 mile)
segment of the longest channel discovered on Venus to date.  The channel is
approximately 1.8 kilometers (1.1 miles) wide.  At over 7000 kilometers
(4200 miles) long, it is at least several hundred kilometers longer than
the Nile River, Earth's longest river; thus, making it the longest known
channel in the solar system.  Both ends of the channel are obscured,
however, so its original length is unknown.

This channel was initially discovered by the Soviet Venera 15-16 orbiters,
which, in spite of their 1 kilometer resolution, detected over 1000
kilometers of the channel.  These channel-like features are common on the
plains of Venus.  In some places they appear to have been formed by lava
which may have melted or eroded a path over the plains' surface.  They
resemble terrestrial meandering rivers superficially.  Most are 1-3
kilometers (.6 to 2 miles) wide, though one degraded channel is 12
kilometers (7.4 miles) wide.  They often exhibit meanders, cutoff oxbows,
and abandoned channel segments, though they are not as tightly sinuous as
terrestrial rivers.  Most are partly buried by younger lava plains, making
their sources difficult to identify.  A few have terminal deposits, vast
radar-dark plains units associated with them, suggesting large flow
volumes.  These channels appear to be older than other channel types, as
they are crossed by fractures and wrinkle ridges, and are often buried by
other volcanic materials.  In addition, they appear to run both upslope and
downslope, suggesting that the plains formed and were later warped by
regional tectonism.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38850
                                  9/13/91

This compressed resolution radar mosaic from Magellan at 49 degrees north
latitude, 165 degrees east longitude, shows a 600 kilometer (360 mile)
segment of the longest channel discovered on Venus to date.  The channel is
approximately 1.8 kilometers (1.1 miles) wide.  At over 7,000 kilometers
(4,340 miles) long, it is at least several hundred kilometers longer than
the Nile River, Earth's longest river, thus making it the longest known
channel in the solar system.  Both ends of the channel are obscured,
however, so its original length is unknown.  This channel was initially
discovered by the Soviet Venera 15-16 orbiters, which, in spite of their 1
kilometer resolution, detected over 1,000 kilometers of the channel.  These
channel-like features are common on the plains of Venus.  In some places
they appear to have been formed by lava which may have melted or eroded a
path over the plains' surface.  They resemble terrestrial meandering rivers
superficially.  Most are 1-3 kilometers (0.6 to 2 miles) wide, though one
degraded channel is 12 kilometers (7.4 miles) wide.  They often exhibit
meanders, cutoff oxbows, and abandoned channel segments, though they are
not as tightly sinuous as terrestrial rivers.  Most are partly buried by
younger lava plains, making their sources difficult to identify.  A few
have terminal deposits, vast radar-dark plains units associated with them,
suggesting large flow volumes.  These channels appear to be older than
other channel types, as they are crossed by fractures and wrinkle ridges,
and are often buried by other volcanic materials.  In addition, they appear
to run both upslope and downslope, suggesting that the plains formed and
were later warped by regional tectonism.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38851  MGN-65
                                        August 30, 1991

This compressed resolution radar mosaic from Magellan at 49 degrees north
latitude, 165 degrees east longitude with dimensions of 460 x 460
kilometers (285 x 285 miles), shows a 600 kilometer (360 mile) segment of
the longest channel discovered on Venus to date.  The channel is
approximately 1.8 kilometers (1.1 miles) wide.  At over 7000 kilometers
(4200 miles) long, it is over several hundred kilometers longer than the
Nile River, Earth's longest river; thus, making it the longest known
channel in the solar system.  Both ends of the channel are obscured,
however, so its original length is unknown.

This channel was initially discovered by the Soviet Venera 15/16 orbiters,
which, in spite of their 1 kilometer resolution, detected over 1000
kilometers of the channel.  Channel-like features are common on the plains
of Venus.  In some places they appear to have been formed by lava which may
have melted or thermally eroded a path over the plains' surface.  Most are
1-3 kilometers (.6 to 2 miles) wide, though one degraded channel is 12
kilometers (7.4 miles) wide.  They resemble terrestrial meandering rivers
in some aspects with meanders, cutoff oxbows, and abandoned channel
segments.  However, Venus channels are not as tightly sinuous as
terrestrial rivers.  Most are partly buried by younger lava plains, making
their sources difficult to identify.  A few have vast radar-dark plains
units associated with them, suggesting large flow volumes.  These channels
with large deposits appear to be older than other channel types, as they
are crossed by fractures and wrinkle ridges, and are often buried by other
volcanic materials.  In addition, they appear to run both upslope and
downslope, suggesting that the plains were warped by regional tectonism
after channel formation.  Restoration of the Magellan data is about 120
meters (400 feet).
                          MAGELLAN PROJECT OFFICE

                                  P-38852
                                  8/30/91

This map shows the location on Venus of the long lava channel named Hildr.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38853
                                  8/30/91

This map shows the location on Venus of the long lava channel named Hildr.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38856
                                  8/21/91

This Magellan mosaic is centered about 27 degrees south latitude and 200
degrees east longitude in the northern Imdr Region of Venus.  The image,
which is 600 kilometers x 600 kilometers (372 miles x 372), shows numerous
wind streaks.  Wind streaks are produced downwind of a topographic obstacle
where debris is either deposited or removed.  In this image, the bright
teardrop shape streaks located downwind of small volcanic cones most likely
are regions of non-deposition or scouring.  Hence, these streaks are bright
because the area surrounding the streak has been filled in by debris that
makes the terrain smoother and therefore darker in the radar image.  Those
streaks that are dark are probably regions where there has been deposition.
The debris in this image most likely came from two large impact craters.
The crater Isabella is a 165-kilometer (102 mile) diameter crater located
400 kilometers (248 miles) southeast of the image.  Some of the ejecta from
Isabella can be seen in the lower right of the image.  The crater Stanton
is a 108-kilometer (67 mile) diameter crater located 300 kilometers (186
miles) north of the image.

If one were to follow the wind streaks from the bottom of the image to the
top, the streaks at the lower left are bright fan streaks downwind of
volcanic cones.  These streaks indicate an eastward wind direction.  To the
northeast are bright and dark streaks indicating a northeast flow.  Moving
to the northwest are hundreds of very fine dark streaks indicating a
northeast flow.  Directly east of these streaks are about thirty
spectacular teardrop-shape bright streaks associated with small volcanic
domes.  These streaks also indicate a northeast wind flow towards the
equator.

Finally, in the upper left and lower right of the image are small lava
channels.  These channels may have formed by drainage of lava or they may
be the result of lava erosion.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-38857
                                  8/21/91

This spectacular Magellan image is centered on 30 degrees south latitude,
135 degrees east longitude, spans 3500 kilometers (2170 miles) from east to
west (left to right), and shows the near-circular trough of Artemis Chasma.
Its circular shape and size (2100 km or 1302 miles in diameter) make
Artemis the largest corona identified to date on the surface of Venus.
Artemis could encompass most of the U.S. from the Front Range of the
Rockies (near Denver) to the West Coast and is approximately twice the
diameter of the next-smaller corona Heng-O.  Coronae are characterized by a
ring of concentric features surrounding an interior which typically
contains fractures of varying orientations and volcanic features ranging
from individual flows and small (<20 kilometer [12 mile]) volcanoes up to
large (>100 kilometers [62 mile]) shield volcanoes.  Artemis contains
complex systems of fractures, numerous flows and small volcanoes, and at
least two impact craters, the larger of which is located in the lower left
(southwest) quadrant of the feature.  The ring of fractures that defines
Artemis forms a steep trough with raised rims approximately 120 kilometers
(74 miles) wide and with as much as 2.5 kilometers (1.6 miles) of relief
from the rim crest to the bottom of the trough.  Most coronae are thought
to be related to upwelling of hot material from the interior of Venus in
the form of plumes or diapirs, and Artemis may be an extensional trough
related to such an upwelling event.  Raised-rim troughs are most commonly
found to be extensional features (those formed by forces which tend to pull
apart the crust and lithosphere of a planet) but the unusual size and
circularity of Artemis have led to the alternate suggestion that it may be
a zone of intense compression and underthrusting, similar to oceanic
subduction zones on Earth.  Magellan scientists are currently examining
this feature in detail to determine which, if either, of these hypotheses
is correct.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38870  MGN-66
                                        August 30, 1991

A portion of the eastern edge of Alpha Regio is displayed in this three-
dimensional perspective view of the surface of Venus.  The viewpoint is
located at approximately 30 degrees south latitude, 11.8 degrees east
longitude at an elevation of 2.4 kilometers (3.8 miles).  The view is to
the northeast at the center of an area containing seven circular dome-like
hills.  The average diameter of the hills is 25 kilometers (15 miles) with
maximum heights of 750 meters (2,475 feet).  Three of the hills are visible
in the center of the image.  Fractures on the surrounding plains are both
older and younger than the domes.  The surrounding plains are both older
and younger than the domes.  The hills may be the result of viscous or
thick eruptions of lava coming from a vent on the relatively level ground,
allowing the lava to flow in an even lateral pattern.  The concentric and
radial fracture patterns on their surfaces suggests that a chilled outer
layer formed, then further intrusion in the interior stretched the surface.
An alternative interpretation is that domes are the result of shallow
intrusions of molten lava, causing the surface to rise.  If they are
intrusive, then magma withdrawal near the end of the eruptions produced the
fractures.  The bright margins possibly indicate the presence of rock
debris or talus at the slopes of the domes.  Resolution of the Magellan
data is about 120 meters (400 feet).  Magellan's synthetic aperture radar
is combined with radar altimetry to develop a three-dimensional map of the
surface.  A perspective view is then generated from the map.  Simulated
color and a process called radar-clinometry are used to enhance small-scale
structures.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced by the JPL
Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall, Myche
McAuley, and Randy Kirk of the United States Geological Survey, and is a
single frame from the movie released at the May 29, 1991 Magellan news
conference.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38889  MGN-68
                                        August 30, 1991

These two radar images are full resolution mosaics, showing where Magellan
began its mapping of Venus on September 15, 1990 and then completed its
primary mission - one cycle covering all of Venus' 360 degrees of
longitude.  Completion was achieved on May 16, 1991 with 83.7% of the
surface imaged by Magellan.  The bottom image shows data from the start of
mapping on the right mosaicked with data at the end of cycle 1 on the left.
The left side of the top mosaic shows radar imagery from the Soviet Venera
15/16 spacecraft.  Resolution of Venera data is 1 kilometer (.62 miles),
while Magellan's average resolution is 120 meters (400 feet) or about 10
times better than that obtained by Venera.  Centered at 59 degrees north
latitude and 330 east longitude, the images cover an area 260 kilometers
(161 miles) by 210 kilometers (130 miles) where a steep scarp called Vesta
Rupes meets the dark smooth plains of Lakshmi Planum at the top of the
images.  Vesta Rupes consists of ridges which in this image trend primarily
west-northwest.  It descends 1.5 to 2 kilometers (.93 to 1.24 miles) from
Lakshmi Planum in the north to the plains in the south, which themselves
are inclined to the north.  The ridges are crosscut by troughs, implying
that formation of the troughs came after the deformation that caused the
ridges to form.  The troughs and abundant pits may have formed from
collapse after the withdrawal of lava from subsurface lava tubes and
chambers.  The plains at the southern part of the image contain small
ridges and are adjacent to a complexly deformed area in the southwest which
is typical of terrain on Venus called tessera.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38890  MGN-67
                                        August 30, 1991

These two Magellan radar images are centered about 60.5 degrees south
latitude and 348.8 degrees east longitude in the eastern Lavinia Region of
Venus.  The images, which are 110 kilometers (68 miles) in length and 130
kilometers (81 miles) in width, are full resolution mosaics of 14 orbits.
The bottom image was made during cycle 2 of the Magellan mission when the
radar was looking to the right of the spacecraft and at an angle of 25
degrees.  The top image was made at the beginning of the mission when the
radar was looking to the left and at an angle of 20 degrees.  The mission
data at the lower left of the top image represents the beginning of radar
mapping during cycle 1.  Both images show an area with interesting troughs,
which are collapse features.  In the bottom image, the north-south trending
trough has a bright side on the left and a dark side on the right, while in
the top image it is reversed.  This is because the side of the trough
sloping away from the radar appears dark while the side facing the radar
appears bright.  Since the radar was looking from the right in the bottom
image and from the left in the top image, the bright and dark sides for the
trough are reversed between the top and bottom images.  It is very useful
to obtain right-looking and left-looking images of the same area because
features may not be visible from the opposite look direction.  For
instance, there are some fractures that can only be seen in one image.  In
addition, the different incidence angles obtained in cycle 2 of the
mission, will allow scientists to better understand the nature of the Venus
surface.  Resolution of the Magellan data is about 100 meters (400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-38975  MGN-69
                                        August 30, 1991

Landslides on Venus!  The image on the left was taken in late November of
1990 during Magellan's first trip around Venus.  The image on the right was
taken July 23, as the Magellan spacecraft passed over the region for the
second time.  Each image is 24 kilometers (14.4 miles) across and 38
kilometers (23 miles) long, and is centered at 2 degrees south latitude and
74 degrees east longitude.  This pair of Magellan images shows a region in
Aphrodite Terra, within a steeply sloping valley that is cut by many
fractures.  In the center of the image on the right, a bright, flow-like
area can be seen extending to the west (left) of a bright fracture.  The
bright, rough area has appeared and the fracture has changed position in
the 8 months since the first image was made.  A "Venusquake" may have
occurred, producing a new scarp and causing a landslide (the bright area)
to form.  This is the first evidence of active tectonics occurring on other
planets in the solar system.  Resolution of the Magellan data is 120 meters
(400 feet).
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39065  MGN-70
                                        September 27, 1991

Southwest Lakshmi Planum (plains) is bounded on the south by the Danu
Montes (mountains).  Lakshmi Planum is an elevated plateau plain that is
bounded on all sides by mountain chains.  Here, the Danu mountains have an
angular fractured appearance.  Chasms slice diagonally across the mountains
in the lower left (southwest) corner of the image.  Because of the steep
slopes and the local relief of the mountains of several kilometers (2-3
miles), these fault-bounded troughs appear to zig-zag through the mountains
when, in fact, they are probably straight if viewed from above.  The radar
view provides a perspective that would place the viewer's eye to the right
27 degrees above the horizon.  Thus, slopes facing to the right can be seen
completely, though dark, and slopes facing away to the left appear
shortened, often seen only as thin bright lines.  In the center of the
image is a low volcanic dome 20 kilometers (12 miles) in diameter.  This
type of volcanic feature frequently occurs on the low plains.  This dome on
the edge of Lakshmi is deformed and faulted where it has been affected by
the forces that created the Danu mountains.  The image is 75 kilometers (46
miles) on a side.  The center is at 60 degrees north latitude, 324.5
degrees east longitude.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39066  MGN-70
                                        September 27, 1991

This Magellan full-resolution image shows the northern part of the Akna
Montes (Mountains) of Venus.  The Akna range is a north-south trending
ridge belt that forms the western border of the elevated smooth plateau of
Lakshmi Planum (plains).  The Lakshmi plateau plains are formed by
extensive volcanic eruptions and are bounded by mountain chains on all
sides.  The plains appear to be deformed near the mountains.  This suggests
that some of the mountain building activity occurred after the plains
formed.  An impact crater (Official International Astronomical Union name
Wanda, mapped first by the Soviet Venera 15/16 mission in 1984 at low
resolution) with a diameter of 22 kilometers (14 miles) has formed by the
impact of an asteroid into the Akna mountains.  The crater has a rugged
central peak and a smooth radar-dark floor, probably volcanic material.
The crater does not appear to be much deformed by later crustal movement
that uplifted the mountains and crumpled the plains.  Material from the
adjacent mountain ridge to the west, however, appears to have collapsed
into the crater.  Small pits seen to the north of the crater may be
volcanic collapse pits a few kilometers across (1-2 miles).  The ridge of
the Akna mountains immediately to the west of the crater is 8 kilometers
wide (5 miles).  The area in the image is approximately 200 kilometers long
and 125 kilometers wide (130 by 80 miles).  This area is centered at 71.5
degrees north latitude, 324 degrees east longitude.  The resolution of the
Magellan radar system is 120 meters (400 feet).  At this latitude, the
radar views the surface from an angle of 23 degrees off vertical, creating
a perspective as though a viewer were looking at the scene from the right
(east) at an angle of 23 degrees above the surface.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39092
                                        September 27, 1991

This image illustrates the technique used to create one frame of the
computer-generated flyover movie of Venus showing the large volcanos Sif
and Gula Mons.

The radar image mosaic produced by the Magellan spacecraft is shown in its
normal presentation, as though viewed from directly overhead.  Magellan
also measures the elevation (topography) of the surface, directly using its
radar as an altimeter, and indirectly through a technique called
radargrammetry, in which the variations in brightness of the radar image
are interpreted as variations in the slope of the surface.

The red box represents the area of the mosaic used to create one movie
frame.  The cross at the corner of the red box marks the location of the
"camera" above the surface.  The blue line leads to a second cross at the
center of the scene, while the two green lines mark the edges of the scene.
The viewing location of the "camera" is also controlled in its height above
the surface.

Each movie frame is generated by calculating what the scene would look like
from the "camera" position, looking in the chosen direction.  The flat
radar image is registered onto the elevation model, as though it were
draped over the rises and falls of the terrain.  The computer determines
which part of the radar mosaic would be seen in each picture element
(pixel) making up the scene.

In order to create the movie, many frames are assembled in sequence, with
the "camera" location and viewing direction moving smoothly along the
desired flight path.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39093
                                        September 27, 1991

This image illustrates the flight path used to create the computer-
generated flyover movie of Venus showing the large volcanos Sif and Gula
Mons.

The radar image mosaic produced by the Magellan spacecraft is shown in its
normal presentation, as though viewed from directly overhead.  Magellan
also measures the elevation (topography) of the surface, directly using its
radar as an altimeter, and indirectly through a technique called
radargrammetry, in which the variations in brightness of the radar image
are interpreted as variations in the slope of the surface.

The red line represents the flight path of the computer's "camera".  The
camera starts at the upper left, loops around the summit of Sif, moves
south and then east across a smooth plain, crossing two craters on the way.
It then flies north up a bright chasm, directly over the summit of Gula.
It moves back to the west and then east over the dark fallout streak from
an impact crater.  Finally it flies away to the northeast looking back
toward the area it has covered.

Each movie frame is generated by calculating what the scene would look like
from the "camera" position, looking in the chosen direction.  The flat
radar image is registered onto the elevation model, as though it were
draped over the rises and falls of the terrain.  The computer determines
which part of the radar mosaic would be seen in each picture element
(pixel) making up the scene.

In order to create the movie, many frames are assembled in sequence, with
the "camera" location and viewing direction moving smoothly along the
desired flight path.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39144
                                 10/21/91

This full-resolution mosaic centered at 9.4 degrees south latitude, 74
degrees east longitude in the Ovda Region of the Aphrodite Highlands on
Venus is an anaglyph or combined image consisting of two data sets slightly
displaced from each other and projected in red and blue.  This produces a
3-dimensional or stereo effect when viewed through red and blue tinted
glasses.  Magellan "looked" at the surface from different incidence angles
(44 and 24 degrees, from a line normal to the surface) as it passed over
the same part of the surface in the first and second mapping cycle
(November 1990 and July 1991, respectively).  The ability to see both the
radar image and differences in elevation together is valuable for geologic
interpretation.  The image, which is approximately 80 kilometers (49.6
miles) on a side, shows a smooth depression in the upper left of the frame.
Surrounding this depression is a complex ridge-and-valley terrain that sits
at a higher elevation.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39145
                                 10/21/91

This full-resolution mosaic centered at 2 degrees south latitude, 74
degrees east longitude is an anaglyph or combined image consisting of two
data sets slightly displaced from each other and projected in red and blue.
This produces a 3-dimensional or stereo effect when viewed through red and
blue tinted glasses.  Magellan "looked" at the surface from different
incidence angles (44 and 24 degrees, from a line normal to the surface) as
it passed over the same part of the surface in the first and second mapping
cycle (November 1990 and July 1991, respectively).  The brain perceives it
as if there were two large eyes, one at each Magellan position, viewing the
surface while discerning relief.  The ability to see both the radar image
and differences in elevation together is valuable for geologic
interpretation.  The image which is approximately 95 kilometers (58.9
miles) on a side shows scarps and troughs concentric to and radiating from
a 75 kilometer (46.5 mile) depression.  Surrounding the depression is fine
scale complex ridge terrain which may have formed from several events of
compression and extension in different directions.  The fact that the
depression appears dark and lacks most of these ridges may be attributed to
flooding by smooth lava after some of the deformational events.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39146  MGN-78
                                        October 29, 1991

Three impact craters are displayed in this three-dimensional perspective
view of the surface of Venus.  The center of the image is located at
approximately 27 degrees south latitude, 339 degrees east longitude in the
northwestern portion of Lavinia Planitia.  The viewpoint is located
southwest of Howe Crater, which appears centered in the lower portion of
the image.  Howe is a crater with a diameter of 37.3 kilometers (23.1
miles) located at 28.6 degrees south latitude, 337.1 degrees east
longitude.  Danilova, a crater with a diameter of 47.6 kilometers (29.5
miles), located at 26.35 degrees south latitude, 337.25 degrees east
longitude, appears above and to the left of Howe in the image.  Aglaonice,
a crater with a diameter of 62.7 kilometers (38.9 miles), located at 26.5
degrees south latitude, 340 degrees east longitude, is shown to the right
of Danilova.  Magellan synthetic aperture radar data is combined with radar
altimetry to develop a three-dimensional map of the surface.  Rays cast in
a computer intersect the surface to create a three-dimensional perspective
view.  Simulated color and a digital elevation map developed by the U.S.
Geological Survey are used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced at the JPL Multimission Image
Processing Laboratory and is a single frame from a video released at the
May 29, 1991, JPL news conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39147  MGN-79
                                        October 29, 1991

This Magellan image depicts a stereoscopic pair of an area on Venus with
small volcanic domes.  Stereoscopic images of Venus offer exciting new
possibilities for scientific analysis of Venusian landforms, such as the
domes shown here, impact craters, graben - long rifts bounded by faults -
and other geologic features.  Stereopsis, or a three-dimensional view of
this scene, may be obtained by viewing with a stereoscope.  One may also
cut this photograph into two parts and look at the left image with the left
eye and the right image with the right eye; conjugate images (the same
features) should be about 5 centimeters (2 inches) apart when viewing.
This area is located at 38.4 degrees south latitude and 78.3 degrees east
longitude.  The incidence, or look, angle of the left image is 28.5 degrees
and that of the right image is 15.6 degrees.  Radar illumination for both
images comes from the left.  A small dome at left center is about 140
meters (462 feet) high and 6 kilometers (3.7 miles) wide.  Other domes with
smaller relief can be perceived in three dimensions.  At the smaller
incidence angle used to acquire the image on the right, radar brightness is
more sensitive to small changes in topography.  This enhances the
visibility of many of the domes in this scene.
                          MAGELLAN PROJECT OFFICE

                                  P-39163
                                  1/17/92

A portion of Western Eistla Regio is displayed in this three-dimensional
perspective view of the surface of Venus.  The viewpoint is located 725
kilometers (450 miles) southeast of Gula Mons, at an elevation of 1.2
kilometers (0.74 miles).  A rift valley, shown in the foreground, extends
to the base of Gula Mons, a 3 kilometer (1.86 miles) high volcano.  We are
looking to the northwest with Gula Mons appearing at the right on the
horizon.  Gula Mons is located at approximately 22 degrees north 359
degrees east.  Sif Mons, a volcano with a diameter of 300 kilometers (180
miles) and a height of 2 kilometers (1.2 miles), appears to the left of
Gula Mons in the background.  Magellan synthetic aperture radar data is
combined with radar altimetry to develop a three-dimensional map of the
surface.  Ray tracing is used to generate a perspective view from this map.
The vertical scale is exaggerated approximately 23 times.  Simulated color
and a digital elevation map developed by the U. S. Geological Survey are
used to enhance small scale structure.  The simulated hues are based on
color images recorded by the Soviet Venera 13 and 14 spacecraft.  The image
was produced at the JPL Multimission Image Processing Laboratory by Eric De
Jong, Jeff Hall, and Myche McAuley, and is a single frame from the movie
released at the March 5, 1991, press conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39164
                                        November 7, 1991

Stuart crater is displayed in this image of the surface of Venus, which was
created in a computer using Magellan radar data.  The viewpoint is located
east of Stuart crater at an elevation above the surface of 1.6 kilometers
(1 mile).  Stuart crater, named for Mary Stuart, Queen of Scots, is located
at approximately 30.75 degrees south latitude, 20.20 degrees east
longitude, and has a diameter of 67 kilometers (41.5 miles).  The image is
made by combining in a computer Magellan synthetic aperture radar data with
radar altimetry.  The computer processing produces a three-dimensional
perspective of the surface.  The vertical scale in this perspective has
been exaggerated 22.5 times.  Simulated color and a digital elevation map
developed by the U.S. Geological Survey are used to enhance small-scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced by the Solar
System Visualization project and the Magellan Science team at the JPL
Multimission Image Processing Laboratory, and is a single frame from a
video released at the May 29, 1991, JPL news conference.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39165
                                        November 7, 1991

A volcano with a fluted rim is displayed in this image of the surface of
Venus which was created in a computer from Magellan radar data.  The
viewpoint is located 50 kilometers (31 miles) northwest of the volcano, at
a height of 0.6 kilometers (0.47 miles) above the volcano.  The image is
centered at 5.5 degrees east longitude, 18 degrees south latitude, 25
kilometers (16 miles) north of the complex-ridged terrain of Alpha Regio.
The volcano is approximately 66 kilometers (41 miles) across at the base,
with a concave summit 35 kilometers (22 miles) in diameter.  Dark lava
flows emanate from a shallow summit pit.  The sides of the volcanic edifice
are characterized by radiating ridges and valleys that impart a fluted
appearance.  The image is made by combining in a computer Magellan
synthetic aperture radar data with radar altimetry.  The computer
processing produces a three-dimensional perspective of the surface.
Simulated color and a digital elevation map developed by the U.S.
Geological Survey, are used to enhance small scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced at the JPL Multimission Image
Processing Laboratory, and is a single frame from a video released at the
May 29, 1991, JPL news conference.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39166
                                        November 7, 1991

Gula Mons and Cunitz crater are displayed in this image of the surface of
Venus which was created in a computer using Magellan radar data.  The
viewpoint is located 1,310 kilometers (812.2 miles) west of Gula Mons and
is 1.6 kilometers (1 mile) above the surface at Eistla Regio.  The view is
to the east with Gula Mons appearing on the horizon.  Gula Mons, a 3-
kilometer (1.9-mile) high volcano, is located at approximately 22 degrees
north latitude, 359 degrees east longitude in western Eistla Regio.  The
impact crater displayed in the center of the image is named after the
astronomer and mathematician, Maria Cunitz.  Cunitz crater is 48.5
kilometers (30 miles) in diameter and is located at approximately 14.5
degrees north latitude, 350 degrees east longitude.  The image is made by
combining Magellan synthetic aperture radar data with radar altimetry.  The
computer processing produces a three-dimensional perspective of the
surface.  The vertical scale in this perspective has been exaggerated 22.5
times.  Simulated color and a digital elevation map developed by the U.S.
Geological Survey are used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced by the Solar System Visualization
project and the Magellan Science team at the JPL Multimission Image
Processing Laboratory, and is a single frame from a video released at the
March 5, 1991, JPL news conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39167
                                  1/17/92

A caldera on Gula Mons is displayed in this computer-simulated view of the
surface of Venus.  The viewpoint is located at a height of 1.6 kilometers
(1 mile) above the caldera.  The caldera has a diameter of approximately 25
kilometers (15.5 miles).  Lava flows extend for hundreds of kilometers
across the fractured plains shown in the background.  The view is to the
north.  Magellan synthetic aperture radar data is combined with radar
altimetry to produce a three-dimensional map of the surface.  Rays cast in
a computer intersect the surface to create a three-dimensional perspective
view.  The vertical scale is exaggerated approximately 23 times.  Simulated
color and a digital elevation map developed by the U. S. Geological Survey
are used to enhance small-scale structure.  The simulated hues are based on
color images recorded by the Soviet Venera 13 and 14 spacecraft.  The image
was produced by the Solar System Visualization project and the Magellan
Science team at the JPL Multimission Image Processing Laboratory, and is a
single frame from a video released at a March 5, 1991, JPL news conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
                          MAGELLAN PROJECT OFFICE

                                  P-39168
                                  1/17/92

A portion of Alpha Regio is displayed in this three-dimensional perspective
view of the surface of Venus.Alpha Regio, a topographic upland
approximately 1300 kilometers across, is centered on 25 degrees south
latitude, 4 degrees east longitude.  In 1963, Alpha Regio was the first
feature on Venus to be identified from earth-based radar.  The radar-bright
area of Alpha Regio is characterized by multiple sets of intersecting
trends of structural features such as ridges, troughs, and flat-floored
fault valleys that, together, form a polygonal outline.  Directly south of
the complex ridged terrain is a large ovoid-shaped feature named Eve.  The
radar-bright spot located centrally within Eve marks the location of the
prime meridian of Venus.  Magellan synthetic aperture radar data is
combined with radar altimetry to develop a three-dimensional map of the
surface.  Ray tracing is used to generate a perspective view from this map.
The vertical scale is exaggerated approximately 23 times.  Simulated color
and a digital elevation map developed by the U. S. Geological Survey are
used to enhance small scale structure.  The simulated hues are based on
color images recorded by the Soviet Venera 13 and 14 spacecraft.  The image
was produced at the JPL Multimission Image Processing Laboratory by Eric De
Jong, Jeff Hall, and Myche McAuley, and is a single frame from the movie
released at the March 5, 1991, press conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
                          MAGELLAN PROJECT OFFICE

                                  P-39175
                                 10/21/91

This Magellan image is centered at 4 degrees south latitude and 157 degrees
east longitude in the Thetis Region of Venus.  The image is approximately
525 kilometers (326 miles) wide at the base and shows Franklin, an impact
crater 72 kilometers (45 miles) in diameter.  The crater is complex,
characterized by a partial central ring and a floor flooded by radar-dark
materials.  Hummocky, rough-textured ejecta extend up to 60 kilometers (37
miles) from the crater rim.  The crater is most remarkable for the
extensive flows that appear to have travelled over 300 kilometers (186
miles) from the crater walls.  These flows are striking against the darker
underlying plains and may represent large volumes of impact melt.
Alternatively, they may be the result of volcanic material released from
the subsurface during the cratering event.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39191  MGN-75
                                        October 21, 1991

This Magellan mosaic is of an area centered about 67 degrees north latitude
and 90 degrees east longitude in the Tellus Region of Venus.  The area
imaged is 340 kilometers (211 miles) in length and 190 kilometers (118
miles) in width and shows a possible dune field on Venus.  The dune field
is located in a valley between Ishtar Terra and Meshkenet Tessera.  It
covers about 17,120 square kilometers (6,506 square miles) and has about 40
radar-bright linear wind streaks.  The dunes range from 0.5 to 10
kilometers (0.3 to 6.2 miles) in length, and are about 0.2 kilometers (0.1
miles) wide and have an average spacing of 0.5 kilometers (0.3 miles).  The
orientation of the dunes and the wind streaks in the southern part of the
field indicates a southeast to northeast wind flow that shifts to a
westward flow in the northern part of the field.  Two bright streaks near a
12-kilometer (7.4 mile) diameter crater north of the dune field also
suggest westward wind flow.  The streaks indicate that the dunes are
oriented perpendicular to the prevailing winds.  On Earth, windblown sand
accumulates in dunes usually at angles no greater than 33 degrees.  With
radar, the faces of dunes normally can only be seen with look-angles of
less than 33 degrees aimed directly into the faces of the dunes.  It is
assumed that windblown dunes would form the same way on Venus.  These
dunes, however, were viewed at an angle of 22 degrees and most of them are
parallel to the radar angle rather than perpendicular to it.  They may be
visible to the radar because of the change in roughness across the dunes.
Rough surfaces show up brightly in radar illumination.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39194
                                        October 29, 1991

This full-resolution mosaic centered at 1.3 degrees north latitude, 73.8
degrees east longitude in the Ovda Region of the Aphrodite Highlands on
Venus is an anaglyph or combined image consisting of two data sets slightly
displaced from each other and projected in red and blue.  This produces a
3-dimensional or stereo effect when viewed through red and blue tinted
glasses.  Magellan "looked" at the surface from different incidence angles
(44 and 24 degrees, from a line perpendicular to the surface) as it passed
over the same part of the surface in the first and second mapping cycle
(November 1990 and July 1991, respectively).  The ability to see both the
radar image and differences in elevation together is valuable for geologic
interpretation.  The image, which is of an area approximately 100
kilometers (62 miles) on a side, shows a complex pattern of troughs,
ridges, and depressions.  A steep ridge running approximately northeast-
southwest marks the boundary between a zone of fractured plains to the
northwest and a deep quasi-circular depression to the southeast.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39195
                                        October 29, 1991

This full-resolution mosaic centered at 59.1 degrees south latitude, 86.5
degrees east longitude in the Lada Terra Region on Venus is an anaglyph, or
combined image, consisting of two data sets slightly displaced from each
other and projected in red and blue.  This produces a 3-dimensional or
stereo effect when viewed through red and blue tinted glasses.  Magellan
"looked" at the surface from different incidence angles (20 and 14 degrees
from a line perpendicular to the surface) as it passed over the same part
of the surface in the first and second mapping cycles (November 1990 and
July 1991, respectively).  The ability to see both the radar image and
differences in elevation together is valuable for geologic interpretation.
The image is of an area approximately 100 kilometers (62 miles) on a side
and shows a deep trough approximately 110 kilometers (68 miles) long, and 8
to 12 kilometers (5 to 7 miles) wide.  Analysis of geometric distortions in
the two images shows the trough to be about 800 meters (0.5 mile) deep.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39196
                                        October 29, 1991

This full-resolution mosaic centered at 1.9 degrees south latitude, 73.8
degrees east longitude in the Ovda Region of the Aphrodite Highlands on
Venus is an anaglyph or combined image consisting of two data sets slightly
displaced from each other and projected in red and blue.  This produces a
3-dimensional or stereo effect when viewed through red and blue tinted
glasses.  Magellan "looked" at the surface from different incidence angles
(44 and 24 degrees, from a line perpendicular to the surface) as it passed
over the same part of the surface in the first and second mapping cycles
(November 1990 and July 1991, respectively).  The ability to see both the
radar image and differences in elevation together is valuable for geologic
interpretation.  The image, which is of an area approximately 200
kilometers (124 miles) on a side, shows an extremely complex, tectonically
disrupted terrain which displays dramatic topography.  The dark circular
region near the center of the image sits as much as 3 kilometers (2 miles)
lower than the ridges to the west.  The complex pattern of ridges and
troughs indicates the region has experienced a series of tectonic events,
including faulting, uplift, and collapse.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39224  MGN 80
                                        October 29, 1991

The northern hemisphere is displayed in this global view of the surface of
Venus.  The north pole is at the center of the image, with 0 degrees, 90
degrees, 180 degrees, 270 degrees east longitudes at the 6, 3, 12, and 9
o'clock positions, respectively, of an imaginary clock face.  Magellan
synthetic aperture radar mosaics from the first cycle of Magellan mapping
are mapped onto a computer-simulated globe to create this image.  Data gaps
are filled with Pioneer-Venus Orbiter data, or a constant mid-range value.
Simulated color is used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced by the Solar System Visualization
project and the Magellan Science team at the JPL Multimission Image
Processing Laboratory, and is a single frame from a video released at the
October 29, 1991, JPL news conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39225  MGN 81
                                        October 29, 1991

This global view of the surface of Venus is centered at 180 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping are mapped onto a computer-simulated globe to create
this image.  Data gaps are filled with Pioneer-Venus Orbiter data, or a
constant mid-range value.  Simulated color is used to enhance small-scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced by the Solar
System Visualization project and the Magellan Science team at the JPL
Multimission Image Processing Laboratory, and is a single frame from a
video released at the October 29, 1991, JPL news conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39226  MGN-82
                                        October 29, 1991

This full resolution radar mosaic from Magellan at 49 degrees south
latitude, 273 degrees east longitude of an area with dimensions of 130 by
190 kilometers (81 by 118 miles), shows a 200 kilometer (124 mile) segment
of a sinuous channel on Venus.  The channel is approximately 2 kilometers
(1.2 miles) wide.  These channel-like features are common on the plains of
Venus.  In some places they appear to have been formed by lava which may
have melted or thermally eroded a path over the plains' surface.  Most are
1 to 3 kilometers (0.6 to 2 miles) wide.  They resemble terrestrial rivers
in some respects, with meanders, cutoff oxbows, and abandoned channel
segments.  However, Venus channels are not as tightly sinuous as
terrestrial rivers.  Most are partly buried by younger lava plains, making
their sources difficult to identify.  A few have vast radar-dark plains
units associated with them, suggesting large flow volumes.  These channels
appear to be older than other channel types on Venus, as they are crossed
by fractures and wrinkle ridges, and are often buried by other volcanic
materials.  In addition, they appear to run both upslope and downslope,
suggesting that the plains were warped by regional tectonism after channel
formation.  Resolution of the Magellan data is about 120 meters (400 feet).
                          MAGELLAN PROJECT OFFICE

                                  P-39230
                                 10/29/91

This full resolution radar mosaic from Magellan at 50 degrees south
latitude, 273 degrees east longitude with dimensions of 80 by 60 kilometers
(50 by 37 miles), shows a 90 kilometer (56 mile) segment of a sinuous
channel on Venus.  The channel is approximately 2 kilometers (1.2 miles)
wide.  These channel-like features are common on the plains of Venus.  In
some places they appear to have been formed by lava which may have melted
or thermally eroded a path over the plains' surface.  Most are 1 to 3
kilometers (0.6 to 2 miles) wide.  They resemble terrestrial rivers in some
respects, with meanders, cutoff oxbows, and abandoned channel segments.
However, Venus channels are not as tightly sinuous as terrestrial rivers.
Most are partly buried by younger lava plains, making their sources
difficult to identify.  A few have vast radar-dark plains units associated
with them, suggesting large flow volumes.  These channels appear to be
older than other channel types on Venus, as they are crossed by fractures
and wrinkle ridges, and are often buried by other volcanic materials.  In
addition, they appear to run both upslope and downslope, suggesting that
the plains were warped by regional tectonism after channel formation.
Resolution of the Magellan data is about 120 meters (400 feet).

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39326  MGN-83
                                        October 29, 1991

Maat Mons is displayed in this three-dimensional perspective view of the
surface of Venus.  The viewpoint is located 560 kilometers (347 miles)
north of Maat Mons at an elevation of 1.7 kilometers (1 mile) above the
terrain.  Lava flows extend for hundreds of kilometers across the fractured
plains shown in the foreground, to the base of Maat Mons.  The view is to
the south with Maat Mons appearing at the center of the image on the
horizon.  Maat Mons, an 8 kilometer (5 mile) high volcano, is located at
approximately 0.9 degrees north latitude, 194.5 degrees east longitude.
Magellan synthetic aperture radar data is combined with radar altimetry to
develop a three-dimensional map of the surface.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.
Simulated color and a digital elevation map developed by the U. S.
Geological Survey, are used to enhance small-scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced at the JPL Multimission Image
Processing Laboratory.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109 TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39342
                                        November 25, 1991

Every 243 days (one Venus "day"), the Magellan spacecraft returns to the
same position over the surface of the planet.  This provides the
opportunity to view the same terrain with a different set of radar
instrument parameters.  This image pair shows two views of an area in the
Ovda Region of the Aphrodite highlands (center latitude 8 degrees south,
longitude 74 degrees east).  The area shown is approximately 80 kilometers
(49.6 miles) across and 220 kilometers (136.4 miles) top-to-bottom.  The
left image was acquired in November 1990 during the first mapping cycle;
the right image was acquired in July 1991 during the second mapping cycle.
The images were acquired at different view angles (43 degrees from vertical
in cycle 1, 23 degrees from vertical in cycle 2).  This difference creates
slightly different distortions related to topographic variations.  By
viewing the images one to each eye (left image to left eye, right image to
right eye), a three dimensional "stereo" effect is created.  A total of
about 2.6 kilometers (1.6 miles) of elevation difference are present in
this scene.  Fine details of topography are revealed by this technique,
which greatly aid in the geological interpretation of the image data.  The
smooth radar-dark area in the lower part of the frame is seen to be a
depression, which is surrounded by complex ridge-and-valley terrain that
sits at a higher elevation.  Mission planners anticipate that Magellan will
operate in "stereo" mode, with incidence angles complementary to cycle one,
during most of cycle three in 1992.
                          MAGELLAN PROJECT OFFICE

                                  P-39374
                                  11/4/91

This image shows color-coded elevation overlaid on a shaded relief
perspective view of Alpha Regio, based on Magellan altimetry.  This area,
about 750 miles across, is one of the most topographically complex to be
found on Venus, and shows surface roughness at virtually all scale sizes
from a few inches up to a hundred miles.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39375
                                  11/4/91

This image shows Mercator (above) and polar stereographic (below) color-
coded maps of elevations on Venus, as derived from the first eight months
of Magellan altimetric observations.  A small amount of shading has been
added to emphasize steep slopes.  The large highland area in the north is
Ishtar Terra, containing the highest mountains (called Maxwell) on the
planet.  Aphrodite Terra, another important highland, is draped along the
equator to the right.  Regions shown in gray have not yet been observed by
Magellan, but show the coarser results of the 1978 Pioneer Venus mission.
Over 90% of the planet has been mapped in this image.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39380  MGN-84
                                        November 7, 1991

The western half of Venus is displayed in this simple cylindrical map of
the planet's surface.  The left edge of the image is at 240 degrees east
longitude, the right edge at 67.5 degrees east longitude.  The top and
bottom of the image are at 90 degrees north latitude and 90 degrees south
latitude, respectively.  Magellan synthetic aperture radar mosaics from the
first cycle of Magellan mapping are mapped onto a rectangular latitude-
longitude grid to create this image.  Data gaps are filled with Pioneer-
Venus Orbiter altimetric data, or a constant mid-range value.  Simulated
color is used to enhance small-scale structure.  The simulated hues are
based on color images recorded by the Soviet Venera 13 and 14 spacecraft.
The image was produced by the Solar System Visualization project and the
Magellan Science team at the JPL Multimission Image Processing Laboratory.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-39381  MGN-85
                                        November 7, 1991

The eastern half of the planet is displayed in this simple cylindrical map
of the surface of Venus.  The left edge of the image is at 52.5 degrees
east longitude, the right edge of 240 degrees east longitude.  The top and
bottom of the image are at 90 degrees north latitude and 90 degrees south
latitude, respectively.  Magellan synthetic aperture radar mosaics from the
first cycle of the Magellan mapping are mapped onto a rectangular latitude-
longitude grid to create this image.  Data gaps are filled with Pioneer-
Venus Orbiter altimetric data, or a constant mid-range value.  Simulated
color is used to enhance small-scale structure.  The simulated hues are
based on color images recorded by the Soviet Venera 13 and 14 spacecraft.
The image was produced by the Solar System Visualization project and the
Magellan Science team at the JPL Multimission Image Processing Laboratory.
                          MAGELLAN PROJECT OFFICE

                                  P-39570
                                  1/17/92

This global view of the surface of Venus is centered at 0 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping are mapped onto a computer-simulated globe to create
this image.  Data gaps are filled with Pioneer-Venus Orbiter data, or a
constant mid-range value.  Simulated color is used to enhance small-scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced by the Solar
System Visualization project and the Magellan Science team at the JPL
Multimission Image Processing Laboratory, and is a single frame from a
video released at the October 29, 1991, JPL news conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
                          MAGELLAN PROJECT OFFICE

                                  P-39571
                                  1/17/92

This global view of the surface of Venus is centered at 90 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping are mapped onto a computer-simulated globe to create
this image.  Data gaps are filled with Pioneer-Venus Orbiter data, or a
constant mid-range value.  Simulated color is used to enhance small-scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced by the Solar
System Visualization project and the Magellan Science team at the JPL
Multimission Image Processing Laboratory, and is a single frame from a
video released at the October 29, 1991, JPL news conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
                          MAGELLAN PROJECT OFFICE

                                  P-39572
                                  1/17/92

This global view of the surface of Venus is centered at 270 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping are mapped onto a computer-simulated globe to create
this image.  Data gaps are filled with Pioneer-Venus Orbiter data, or a
constant mid-range value.  Simulated color is used to enhance small-scale
structure.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.  The image was produced by the Solar
System Visualization project and the Magellan Science team at the JPL
Multimission Image Processing Laboratory, and is a single frame from a
video released at the October 29, 1991, JPL news conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
                          MAGELLAN PROJECT OFFICE

                                  P-39573
                                  1/17/92

The southern hemisphere is displayed in this global view of the surface of
Venus.  The south pole is at the center of the image, with 0 degrees, 90
degrees, 180 degrees, 270 degrees east longitudes at the 12, 3, 6, and 9
o'clock positions, respectively, of an imaginary clock face.  Magellan
synthetic aperture radar mosaics from the first cycle of Magellan mapping
are mapped onto a computer-simulated globe to create this image.  Data gaps
are filled with Pioneer-Venus Orbiter data, or a constant mid-range value.
Simulated color is used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced by the Solar System Visualization
project and the Magellan Science team at the JPL Multimission Image
Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
            Pasadena, Calif.  91109.  Telephone [phone]
                          MAGELLAN PROJECT OFFICE

                                  P-39631
                                  2/5/92

The northern hemisphere is displayed in this global view of the surface of
Venus.  The north pole is at the center of the image, with 0 degrees, 90
degrees, 180 degrees, 270 degrees east longitudes at the 6, 3, 12, and 9
o'clock positions, respectively, of an imaginary clock face.  Magellan
synthetic aperture radar mosaics from the first cycle of Magellan mapping,
and a 5 degree latitude-longitude grid, are mapped onto a computer-
simulated globe to create this image.  Data gaps are filled with Pioneer-
Venus Orbiter data, or a constant mid-range value.  The image was produced
by the Solar System Visualization project and the Magellan Science team at
the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39632
                                  2/5/92

The southern hemisphere is displayed in this global view of the surface of
Venus.  The south pole is at the center of the image, with 0 degrees, 90
degrees, 180 degrees, 270 degrees east longitudes at the 12, 3, 6, and 9
o'clock positions, respectively, of an imaginary clock face.  Magellan
synthetic aperture radar mosaics from the first cycle of Magellan mapping,
and a 5 degree latitude-longitude grid, are mapped onto a computer-
simulated globe to create this image.  Data gaps are filled with Pioneer-
Venus Orbiter data, or a constant mid-range value.  The image was produced
by the Solar System Visualization project and the Magellan Science team at
the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39633
                                  2/5/92

This global view of the surface of Venus is centered at 0 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping, and a 5 degree latitude-longitude grid, are mapped
onto a computer-simulated globe to create this image.  Data gaps are filled
with Pioneer-Venus Orbiter data, or a constant mid-range value.  The image
was produced by the Solar System Visualization project and the Magellan
Science team at the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39634
                                  2/5/92

This global view of the surface of Venus is centered at 90 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping, and a 5 degree latitude-longitude grid, are mapped
onto a computer-simulated globe to create this image.  Data gaps are filled
with Pioneer-Venus Orbiter data, or a constant mid-range value.  The image
was produced by the Solar System Visualization project and the Magellan
Science team at the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39635
                                  2/5/92

This global view of the surface of Venus is centered at 180 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping, and a 5 degree latitude-longitude grid, are mapped
onto a computer-simulated globe to create this image.  Data gaps are filled
with Pioneer-Venus Orbiter data, or a constant mid-range value.  The image
was produced by the Solar System Visualization project and the Magellan
Science team at the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39636
                                  2/5/92

This global view of the surface of Venus is centered at 270 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping, and a 5 degree latitude-longitude grid, are mapped
onto a computer-simulated globe to create this image.  Data gaps are filled
with Pioneer-Venus Orbiter data, or a constant mid-range value.  The image
was produced by the Solar System Visualization project and the Magellan
Science team at the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39657bw  MGN-88
                                        January 27, 1992

This Magellan image shows a portion of Eistla Regio (Region) in the
northern hemisphere of Venus, centered at 1 degrees south latitude, 37
degrees east longitude.  The area is 440 kilometers (270 miles) wide and
350 kilometers (220 miles) long.  This image was produced from Magellan
radar data collected in Cycle Two of the mission.  Cycle Two was completed
January 15, 1992.  The area was not imaged during the first cycle because
of superior conjunction, when the Sun was between the Earth and Venus,
preventing communication with the spacecraft.  This image contains examples
of several of the major geologic terrains on Venus and illustrates the
basic stratigraphy or sequence of geologic events.  The oldest terrains
appear as bright, highly fractured or chaotic highlands rising out of the
plains.  This is seen in the right half of the image.  The chaotic
highlands, sometimes called tessera, may represent older and thicker
crustal material and occupy about 15 percent of the surface of Venus.  The
fractured terrain in this region has a distinctly linear structure with a
shear-like pattern.  Plains surround and embay the fractured highland
tessera.  Plains are formed by fluid volcanic flows that may have once
formed vast lava seas which covered all the low lying surfaces.  Plains
comprise more than 80 percent of the surface of Venus.  The most recent
activity in the region is volcanism that produced the radar bright flows
best seen in the upper left quadrant of the image.  The flows are similar,
in their volcanic origin, to the darker plains volcanics, but apparently
have more rugged surfaces that more efficiently scatter the radar signal
back to the spacecraft.  The geologic sequence is early fracturing of the
tessera, flooding by extensive plains lavas, and scattered, less extensive
individual flows on the plains surface.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39657C  MGN-88
                                        January 27, 1992

This false color Magellan image shows a portion of Eistla Regio (Region) in
the northern hemisphere of Venus, centered at 1 degrees south latitude, 37
degrees east longitude.  The area is 440 kilometers (270 miles) wide and
350 kilometers (220 miles) long.  This image was produced from Magellan
radar data collected in Cycle Two of the mission.  Cycle Two was completed
January 15, 1992.  The area was not imaged during the first cycle because
of superior conjunction, when the Sun was between the Earth and Venus,
preventing communication with the spacecraft.  This image contains examples
of several of the major geologic terrains on Venus and illustrates the
basic stratigraphy or sequence of geologic events.  The oldest terrains
appear as bright, highly fractured or chaotic highlands rising out of the
plains.  This is seen in the right half of the image.  The chaotic
highlands, sometimes called tessera, may represent older and thicker
crustal material and occupy about 15 percent of the surface of Venus.  The
fractured terrain in this region has a distinctly linear structure with a
shear-like pattern.  Plains surround and embay the fractured highland
tessera.  Plains are formed by fluid volcanic flows that may have once
formed vast lava seas which covered all the low lying surfaces.  Plains
comprise more than 80 percent of the surface of Venus.  The most recent
activity in the region is volcanism that produced the radar bright flows
best seen in the upper left quadrant of the image.  The flows are similar,
in their volcanic origin, to the darker plains volcanics, but apparently
have more rugged surfaces that more efficiently scatter the radar signal
back to the spacecraft.  The geologic sequence is early fracturing of the
tessera, flooding by extensive plains lavas, and scattered, less extensive
individual flows on the plains surface.  The simulated hues are based on
color images recorded by the Soviet Venera 13 and 14 spacecraft.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39658bw  MGN-89
                                        January 27, 1992

This Magellan image shows a portion of Bereghinya Planitia (plains) in the
northern hemisphere of Venus, centered at 31 degrees north latitude, 43
degrees east longitude.  The area is 260 kilometers (160 miles) wide and
330 kilometers (200 miles) long.  This image was produced from Magellan
radar data collected in Cycle Two of the mission.  Cycle Two was completed
January 15, 1992.  The area was not imaged during the first cycle because
of superior conjunction, when the Sun was between the Earth and Venus,
preventing communication with the spacecraft.  This image contains examples
of several of the major geologic terrains on Venus and illustrates the
basic stratigraphy or sequence of geologic events.  The oldest terrains
appear as bright, highly fractured or chaotic highlands rising out of the
plains.  This is seen in the upper right and lower left quadrants of the
image.  The chaotic highlands, sometimes called tessera, may represent
older and thicker crustal material and occupy about 15 percent of the
surface of Venus.  Plains surround and embay the fractured highland
tessera.  Plains are formed by fluid volcanic flows that may have once
formed vast lava seas which covered all the low lying surfaces.  Plains
comprise more than 80 percent of the surface of Venus.  The most recent
activity in the region is volcanism that produced the radar bright flows
best seen in the lower right quadrant of the image.  The lava flows in this
image are associated with the shield volcano Tepev Mons whose summit is
near the lower left corner of the image.  The flows are similar to the
darker plains volcanics, but apparently have more rugged surfaces that more
efficiently scatter the radar signal back to the spacecraft.  The geologic
sequence is early fracturing of the tessera, flooding by extensive plains
lavas, and scattered, less extensive individual flows on the plains
surface.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39658C  MGN-89
                                        January 27, 1992

This false color Magellan image shows a portion of Bereghinya Planitia
(plains) in the northern hemisphere of Venus, centered at 31 degrees north
latitude, 43 degrees east longitude.  The area is 260 kilometers (160
miles) wide and 330 kilometers (200 miles) long.  This image was produced
from Magellan radar data collected in Cycle Two of the mission.  Cycle Two
was completed January 15, 1992.  The area was not imaged during the first
cycle because of superior conjunction, when the Sun was between the Earth
and Venus, preventing communication with the spacecraft.  This image
contains examples of several of the major geologic terrains on Venus and
illustrates the basic stratigraphy or sequence of geologic events.  The
oldest terrains appear as bright, highly fractured or chaotic highlands
rising out of the plains.  This is seen in the upper right and lower left
quadrants of the image.  The chaotic highlands, sometimes called tessera,
may represent older and thicker crustal material and occupy about 15
percent of the surface of Venus.  Plains surround and embay the fractured
highland tessera.  Plains are formed by fluid volcanic flows that may have
once formed vast lava seas which covered all the low lying surfaces.
Plains comprise more than 80 percent of the surface of Venus.  The most
recent activity in the region is volcanism that produced the radar bright
flows best seen in the lower right quadrant of the image.  The lava flows
in this image are associated with the shield volcano Tepev Mons whose
summit is near the lower left corner of the image.  The flows are similar
to the darker plains volcanics, but apparently have more rugged surfaces
that more efficiently scatter the radar signal back to the spacecraft.  The
geologic sequence is early fracturing of the tessera, flooding by extensive
plains lavas, and scattered, less extensive individual flows on the plains
surface.  The simulated hues are based on color images recorded by the
Soviet Venera 13 and 14 spacecraft.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39659bw  MGN-90
                                        January 27, 1992

This Magellan image shows a portion of Leda Planitia (plains) in the
northern hemisphere of Venus, centered at 41 degrees north latitude, 52
degrees east longitude.  The area is 220 kilometers (135 miles) wide and
275 kilometers (170 miles) long.  This image was produced from Magellan
radar data collected in Cycle Two of the mission.  Cycle Two was completed
January 15, 1992.  The area was not imaged during the first cycle because
of superior conjunction when the Sun was between the Earth and Venus,
preventing communication with the spacecraft.  This image contains examples
of several of the major geologic terrains on Venus and illustrates the
basic stratigraphy or sequence of geologic events.  The oldest terrains
appear as bright, highly fractured or chaotic highlands rising out of the
plains.  This is seen in the upper left, or northwest, quadrant of the
image.  The chaotic highlands, sometimes called tessera, may represent
older and thicker crustal material and occupy about 15% of the surface of
Venus.  The circular ring structure in the lower left of the image is
probably an impact crater.  This 40 kilometer (25 mile) diameter crater has
been given a proposed name Heloise, after the French physician who lived
from about 1098 to 1164 A.D.  The crater was formed by the impact of an
asteroid sometime before the plains lavas embayed and covered the region.
The plains surround and embay the fractured highland tessera.  Plains are
formed by fluid volcanic flows that may have once formed vast lava seas
which covered all the low lying surfaces.  Plains comprise more than 80
percent of the surface of Venus.  The most recent activity in the region is
volcanism that produced the radar bright flows best seen in the upper right
quadrant of the image.  Those flows are similar to the darker plains
volcanics, but apparently have more rugged surfaces that more efficiently
scatter the radar signal back to the spacecraft.  Thus the geologic
sequence is early fracturing of the tessera, flooding by extensive plains
lavas, and scattered, less extensive individual flows on the plains
surface.  Impact cratering occurs throughout geologic history and provides
a rough estimate of the time scale.  Craters larger than a few kilometers
in diameter form on Venus, as they do on Earth, at the rate of about one
per million years, with smaller impacts much more frequent than larger
ones.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39659C  MGN-90
                                        January 27, 1992

This false color Magellan image shows a portion of Leda Planitia (plains)
in the northern hemisphere of Venus, centered at 41 degrees north latitude,
52 degrees east longitude.  The area is 220 kilometers (135 miles) wide and
275 kilometers (170 miles) long.  This image was produced from Magellan
radar data collected in Cycle Two of the mission.  Cycle Two was completed
January 15, 1992.  The area was not imaged during the first cycle because
of superior conjunction when the Sun was between the Earth and Venus,
preventing communication with the spacecraft.  This image contains examples
of several of the major geologic terrains on Venus and illustrates the
basic stratigraphy or sequence of geologic events.  The oldest terrains
appear as bright, highly fractured or chaotic highlands rising out of the
plains.  This is seen in the upper left, or northwest, quadrant of the
image.  The chaotic highlands, sometimes called tessera, may represent
older and thicker crustal material and occupy about 15% of the surface of
Venus.  The circular ring structure in the lower left of the image is
probably an impact crater.  This 40 kilometer (25 mile) diameter crater has
been given a proposed name Heloise, after the French physician who lived
from about 1098 to 1164 A.D.  The crater was formed by the impact of an
asteroid sometime before the plains lavas embayed and covered the region.
The plains surround and embay the fractured highland tessera.  Plains are
formed by fluid volcanic flows that may have once formed vast lava seas
which covered all the low lying surfaces.  Plains comprise more than 80
percent of the surface of Venus.  The most recent activity in the region is
volcanism that produced the radar bright flows best seen in the upper right
quadrant of the image.  Those flows are similar to the darker plains
volcanics, but apparently have more rugged surfaces that more efficiently
scatter the radar signal back to the spacecraft.  Thus the geologic
sequence is early fracturing of the tessera, flooding by extensive plains
lavas, and scattered, less extensive individual flows on the plains
surface.  Impact cratering occurs throughout geologic history and provides
a rough estimate of the time scale.  Craters larger than a few kilometers
in diameter form on Venus, as they do on Earth, at the rate of about one
per million years, with smaller impacts much more frequent than larger
ones.  The simulated hues are based on color images recorded by the Soviet
Venera 13 and 14 spacecraft.
                          MAGELLAN PROJECT OFFICE

                                  P-39715
                                  2/10/92

Maat Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  The viewpoint is located 560
kilometers (347 miles) north of Maat Mons at an elevation of 1.7 kilometers
(1 mile) above the terrain.  Lava flows extend for hundreds of kilometers
across the fractured plains shown in the foreground, to the base of Maat
Mons.  Maat Mons, an 8 kilometer (5 mile) high volcano, is located at
approximately 0.9 degrees north latitude, 194.5 degrees east longitude.
Maat Mons is named for an Egyptian Goddess of truth and justice.  Magellan
synthetic aperture radar data is combined with radar altimetry to develop a
three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 22.5 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.
Simulated color and a digital elevation map developed by the U. S.
Geological Survey, are used to enhance small-scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced by the Solar System
Visualization project and the Magellan Science team at the JPL Multimission
Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39716
                                  2/10/92

This Magellan image is centered at 74.6 degrees north latitude and 177.3
east longitude, in the northeastern Atalanta Region of Venus.  The image is
approximately 185 kilometers (115 miles) wide at the base and shows
Dickinson, an impact crater 69 kilometers (43 miles) in diameter.  The
crater is complex, characterized by a partial central ring and a floor
flooded by radar-dark and radar-bright materials.  Hummocky, rough-textured
ejecta extend all around the crater, except to the west.  The lack of
ejecta to the west may indicate that the impactor that produced the crater
was an oblique impact from the west.  Extensive radar-bright flows that
emanate from the crater's eastern walls may represent large volumes of
impact melt, or they may be the result of volcanic material released from
the subsurface during the cratering event.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-39717
                                  2/10/92

This unusual Venusian volcano is located on the plains between Artemis
Chasma and Imdr Regio at 37.5 degrees south and 164.5 degrees east.  The
most recent effusions of lavas produced the dome-like structure, about 100
kilometers (62 miles) across, with lava channels that radiate from the
volcano's center.  Lava flowing through one of these channels debouched on
the plains to the lower-left of the volcano and produced a "lava-fan."  The
"dome" is about 0.5 to 1.0 kilometer (.3-.6 mile) high.

Before the "dome" formed, lavas issued from the volcano and formed the
extensive mesa of lavas above, to the right, and below the "dome."  Lobes
of lava along the margins of the mesa and the "dome," are near 60 meters
(198 feet) thick; lava flows as thick as these are very rare on Venus.  The
concentric ridges and troughs on the flows are folds produced by
compression of the cool upper surfaces of the lavas as they flowed.

The earliest deposits are represented by the bright "fingers" at the upper-
right and the bright lobes at the upper-left; dark patches at the lower-
right are areas of non-deposition.  These earliest deposits may have been
produced by an explosive eruption of hot gases and lava fragments that
generated pyroclastic flows.

This volcano shows that magmatic differentiation has occurred on Venus -
just as on our Earth.  The differentiation produced an explosive eruption
of a low-viscosity phase that generated pyroclastic flows and later
effusions of high-viscosity phases of silica-rich lavas that produced the
thick flows of the mesa and the dome-like structure.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                         P-39838, P-39839, P-39840
                                  3/10/92

These three images (P-39840, P-39839, P-39838) illustrate the range in
regional coverage and resolution available in three of the standard
Magellan image data products.  The first image, (P-39840), is a C2-MIDR
(Compressed-twice Mosaicked Image Data Record) centered at 30 degrees north
latitude, 335 degrees east longitude, in the southern Sedna Planitia region
of Venus.  The mosaic covers an area of approximately 27 million square
kilometers, with a pixel spacing of 675 meters, enabling planetary
scientists to characterize the relationships of relatively large-scale
structures on the planet.  Two large volcanoes - Sif Mons and Gula Mons -
can be seen below center right.  Numerous radar-bright lava flows radiate
from the summit calderas of these volcanoes.

The second mosaic, (P-39839), is a C1-MIDR (Compressed-once Mosaicked Image
Data Record) of the region at right center of the first image, centered at
30 degrees north latitude, 350 degrees east longitude.  This image covers
an area of approximately 3 million square kilometers with a pixel spacing
of 225 meters, and shows three times as much detail visible in the first
mosaic.  This scale is most suited to the study of medium-scale structures,
such as the radar-dark streak below center.

The third mosaic, (P-39838), is a full-resolution mosaic centered at 25
degrees north latitude, 357 degrees east longitude.  It covers an area of
approximately 350,000 square kilometers, with a pixel spacing of 75 meters.
This scale allows planetary scientists to examine small-scale structures in
detail, including superposition relationships between lava flows and
surrounding plains, and cross-cutting relationships between sets of fault
troughs or ridges.

The irregular circular feature or corona in the right center of the image
is a low dome approximately 100 kilometers (62 miles) in diameter.  The
corona is flanked by two major lava flows that extend downslope to the
north for several hundred kilometers.  The entire region lies on the
northern flank of a broad regional highland that contains the two volcanic
centers of Sif Mons and Gula Mons.  The dark streak in the upper left of
the image is associated with two small impact craters.  The object that
formed the craters appears to have broken up during its passage through the
dense Venusian atmosphere.  Radar-dark streaks associated with small impact
craters may form from the interaction between an intense shock wave and the
surface, or as a result of deposition of fine-grained ejecta.  The radar-
dark surface is apparently smoother than its surroundings.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-39916  MGN-93
                                        March 16, 1992

This unusual Venusian volcano is located on the plains between Artemis
Chasma and Imdr Regio at 37.5 degrees south latitude and 164.5 degrees east
longitude.  The dome structure with lava channels radiating from the
volcanic center is about 100 km (62 miles) across.  This volcanic feature
has been imaged by Magellan in both left-looking and right-looking modes.
This image, from the second mapping cycle, was taken from the right.  The
volcano and its lava flows appear much the same in both images, but there
are two important differences.  In the left-looking image west-facing
slopes are brighter because they are tilted toward the radar.  In this
right-looking image, west-facing slopes are darker because they face away
from the radar.  Another difference is the image displacement caused by
elevation differences as seen by the radar from the two sides.  The top of
a flow margin is displaced toward the radar relative to its base.  The
displacement is in the opposite direction in the two images.  The sum of
the two displacements is called parallax and can be used to estimate the
height of features.  The topographic relief that can be measured
horizontally is much more precise than can be measured with the altimeter
(about 10 kilometers, or 6 miles).  Parallax measurements show that the
thickness of the lobe of lava at the left-center edges of the image is
variable but typically about 540 meters (1772 feet).  This measurement
conflicts with the altimetry measurement.  The fan-shaped lava flow in the
lower left is about 120 meters (394 feet) thick near its edge.  Lava scarps
on the east side of the complex are about 90 meters (295 feet) high.  (See
P-39717)
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109 TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40030  MGN-94
                                        March 30, 1992

As the Magellan mission has progressed, areas of Venus have become
accessible to the imaging radar system for a second look.  During
Magellan's second 243-day global mapping cycle, the spacecraft was rotated
180 degrees to view the surface from the opposite direction.  This pair of
mosaics shows a region of Venus 575 kilometer (356 miles) by 460 kilometers
(285 miles) as viewed in March 1991 from the left or west (top image) and
in November 1991 from the right or east (bottom image).  This image is
centered at approximately 48 degrees south latitude, 230 degrees east
longitude in the Imdr region of Venus.  The incidence angle of the radar
beam with the surface for both observations was approximately 25 degrees
from vertical.  The dark band near the right edge of the March image is due
to a missing segment of data from one orbit.  Much of the surface appears
different in the two observations.  Some of the darkest areas in the top
image appear patchy and bright in the bottom image.  In addition, east-west
trending, alternating bright and dark bands in the lower left part of the
bottom image are nearly or completely invisible in the top image.  Magellan
scientists are currently evaluating these apparent differences to
understand their origin.  Two theories have been developed.  In one
interpretation, the bright patches in the November (bottom) image are
reflections from facets of surface material that are oriented toward the
east with a slope of approximately 25 degrees.  This would lead to strong
mirror-type reflections that are only visible from the east, the direction
from which the surface was viewed in November.  Under the second
interpretation, the surface itself is proposed to have changed between
image acquisitions.  It is suggested that materials on the surface had been
rearranged sometime during the 8-month period, possibly by near-surface
winds.  Under this interpretation, the apparent brightening of the surface
is explained as a result of the removal of loose material such as dust or
sand, exposing a rougher, rockier surface that would appear brighter in a
radar image.  Magellan scientists hope to obtain a third view of this area
in July 1992, under a viewing geometry similar to the earlier data.  This
should provide the information necessary to distinguish between the
"viewing direction" and "surface change" interpretations.
                          MAGELLAN PROJECT OFFICE

                                  P-40049
                                  4/2/92

This Magellan image, centered at 60 degrees north latitude, 355 degrees
east longitude, is 610 kilometers (378 miles) long by 540 kilometers (335
miles) wide.  At the top of this Magellan full resolution mosaic (F-MIDR)
the elevated plateau Lakshmi Planum drops off from a height of 4 kilometers
(2.5 miles) into deformed lava plains which reside at or near the mean
elevation of Venus.  Intertwining wrinkle ridges, which have bright west
facing slopes are present throughout most of the southern and eastern half
of the image.  Subtle differences in brightness may be attributed to the
roughness of different lava flows (with the bright areas being the
roughest).  The bright, irregular lines in the top left of the image are
fractures which may have formed from the elevated area collapsing under its
own weight due to the flexibility of rock at the hot Venusian surface
temperatures.  The egg-shaped feature in the upper right portion of the
image is a volcanic caldera, 40 kilometers (25 miles) long along its major
axis.  Such features form when lava is extruded from a subsurface chamber
which subsequently collapses leaving a large depression on the surface.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                 P-40142AC
                                  12/1/92

These images present the topography of Venus obtained by the Magellan radar
altimeter, using color to code (see color bar) elevation, and simulated
shading to emphasize relief.  Red corresponds to the highest, blue to the
lowest elevations.  The upper image shows that part of the planet between
69 degrees north and 69 degrees south latitude in Mercator projection;
beneath it are the two polar regions covering latitudes above 44 degrees in
stereographic projection.  Easterly longitudes run across the Mercator map
from left to right, and around the periphery of the polar stereographic
projections.  Height accuracy is better than 50 meters; horizontal
("footprint") resolution of the surface depends on spacecraft altitude,
being about 10 kilometers near the equator and degrading to as much as 25
kilometers at high latitudes.  Gray areas show the coarser results from the
1978 Pioneer Venus mission, and indicate where data had not yet been
obtained by Magellan after the first eight months of operation.

The elevated region in the north is Ishtar Terra, dominated by Maxwell
Montes (the planet's highest mountains) which rise 11 kilometers (36,000
feet) above the planetary mean.  The scorpion-shaped feature extending
along the equator between 70 and 210 degrees longitude is Aphrodite Terra,
a zone that contains several spectacular volcanoes at its eastern limit:
Maat, Ozza and Sapas Montes.  Major geologic feature names are indicated on
the top image.  The altimetric data shown here were analyzed and projected
at the Center for Space Research, Massachusetts Institute of Technology.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40144
                                  5/4/92

These images display the meter-scale roughness of the Venus surface
(characterized by its root-mean-square average slope), as observed by the
Magellan radar altimeter.  The lightest shades locate areas having the
steepest values of average slope, while darker shades indicate areas that
are smoother.  The upper image shows that part of the planet between 69
degrees north and 69 degrees south latitude in Mercator projection; beneath
it are the two polar regions covering latitudes above 44 degrees in
stereographic projection.  Easterly longitudes run across the Mercator map
from left to right, and around the periphery of the polar stereographic
projections.  Resolution of the surface varies with spacecraft altitude,
being about 10 kilometers near the equator and degrading to as much as 25
kilometers at high latitudes.  Black areas indicate where data had not yet
been obtained by Magellan after the first eight months of operation.

There is a tendency for elevated regions, e.g. the Maxwell Montes (left of
the data gap at top center) and Aphrodite Terra (along the equator at
right), to show steeper meter-scale slopes than are typical of lower-lying
areas.  The steeper slopes probably result from disruption of the surface
associated with tectonic activity in these regions.  Note the large 2300-
kilometer (1400-mile) diameter circular feature (Artemis Chasma) in the
lower right of the Mercator image.  This feature is thought to have been
caused by a gigantic plume of heated rock rising from the planet's
interior.  The data shown here were analyzed and projected at the Center
for Space Research, Massachusetts Institute of Technology.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40156  MGN-95
                                        April 22, 1992

Impact craters on Venus have been shown by Magellan radar data to have
properties unlike craters on any other planet in the solar system.  As the
mission has progressed, many areas of the planet, including some containing
unusual crater-related deposits, have become accessible for a second look.
During the second 243-day global mapping cycle, the spacecraft was rotated
180 degrees to view the surface from the opposite side.  This pair of
mosaics shows a region of Venus 860 kilometers by 700 kilometers (515 miles
by 420 miles), as viewed in February, 1991 from the left or west (top
image) and in October, 1991 from the right or east (bottom image).  The
image is centered at approximately 58 degrees south latitude, 200 degrees
east longitude, in the Imdr region of Venus.  Black strips in the top image
are due to missing data.  The incidence angle of the radar beam with the
surface was approximately 21 degrees from vertical in the top image, and 24
degrees from vertical in the bottom image.  The 29 kilometer (17.5 mile)
diameter crater near the center of the image has provisionally been named
Eudocia, for the 5th century Byzantine empress.  Much of the surface
surrounding the crater appears different in the two observations.  Many
patchy bright areas in the top image appear dark in the bottom image.  In
addition, alternating bright and dark bands in the top image are nearly or
completely invisible in the bottom image.  These areas are part of a large
parabolic-shaped feature associated with Eudocia.  Magellan scientists are
currently evaluating these apparent differences to understand their origin.
The bright patches are clearly related to features on the surface, ruling
out an atmospheric source.  Two theories have been developed to explain the
observed differences.  In one interpretation, the bright patches in the
February (top) image are reflections from facets of surface material that
are oriented toward the west with a slope of approximately 21 degrees.
This would lead to strong mirror-type reflections that are only visible
from the west, the direction from which the surface was viewed in February.
These facets may be slopes of small dunes or ripple structures formed by
the wind.  Under the second interpretation, the surface itself is proposed
to have changed between image acquisitions.  It is suggested that materials
on the surface have been rearranged sometime during the 8-month period,
possibly by near-surface winds.  Under this interpretation, the apparent
darkening of the surface is explained as a result of the deposition of
loose material such as dust or sand, covering a rougher, rockier surface
that appears brighter in the earlier image.
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40157  MGN-96
                                        April 22, 1992

Impact craters on Venus have been shown by Magellan radar data to have
properties unlike craters on any other planet in the solar system.  As the
mission has progressed, many areas of the planet, including some containing
unusual crater-related deposits, have become accessible for a second look.
During the second 243-day global mapping cycle, the spacecraft was rotated
180 degrees to view the surface from the opposite side.  This pair of
mosaics shows a region of Venus 860 kilometers by 700 kilometers (515 miles
by 420 miles), as viewed in January, 1991 from the left or west (top image)
and in October, 1991 from the right or east (bottom image).  The image is
centered at approximately 61 degrees south latitude, 184 degrees east
longitude, in the Imdr region of Venus.  The black strip across the top
image is due to a missing orbit.  The incidence angle of the radar beam
with the surface was approximately 20 degrees from vertical in the top
image, and 24 degrees from vertical in the bottom image.  A 45 kilometer
(27 mile) diameter crater, provisionally been named Kuan Tao-Sheng for the
13th century Chinese painter and calligrapher is seen near the center of
the image, along with a 30 kilometer (18 mile) diameter unnamed crater to
the northwest.  Much of the surface surrounding the craters appears
different in the two observations.  Many patchy bright areas in the top
image appear dark in the bottom image, while other areas are bright only in
the bottom image.  These areas are part of a large parabolic-shaped feature
associated with the craters.  Magellan scientists are currently evaluating
these apparent differences to understand their origin.  Two theories have
been developed to explain the observed differences.  In one interpretation,
the bright patches in the January (top) image are reflections from facets
of surface material that are oriented toward the west with a slope of
approximately 20 degrees.  This would lead to strong mirror-type
reflections that are only visible from the west, the direction from which
the surface was viewed in January.  Similar structures having slopes near
24 degrees to the east could occur in the areas that appear bright only in
the October image.  These facets may be slopes of small dunes or ripple
structures formed by the wind.  Under the second interpretation, the
surface itself is proposed to have changed between image acquisitions.  It
is suggested that materials on the surface have been rearranged sometime
during the 8 and 1/2 month period, possibly by near-surface winds.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40158
                                        April 22, 1992

This Magellan full-resolution mosaicked anaglyph centered at 69.5 degrees
north latitude, 355 degrees east longitude covers an area approximately 375
by 450 kilometers (233 by 115 miles), located north of the 10 kilometer
high (6.2 mile) mountain belt called Maxwell Montes.  An anaglyph is a type
of image consisting of two data sets which are slightly displaced from one,
another and projected in red and blue so that a 3-dimensional or stereo
effect is produced when the image is viewed through red and blue tinted
glasses.  The images were obtained when Magellan "looked" at the same part
of the surface from different angles during its first and third mapping
cycles (October 1990 and February 1992, respectively).  The ability to see
both the radar image and differences in elevation together is valuable for
geologic interpretation.  The image is dominated by volcanic plains (the
radar-dark or smooth areas) and tessera (the rough contorted terrain which
is unique to Venus).  The radar-bright terrain at the bottom right of the
image is believed to be an unusual mineral alteration covering most of
Maxwell Montes.  Slightly north of this are large, dome-shaped areas whose
morphologies are not visible in the 2-dimensional radar images.  The image
was produced at the JPL Multimission Image Processing Laboratory.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40159
                                        April 22, 1992

This Magellan full-resolution mosaicked anaglyph centered at 66.5 degrees
north latitude, 0.0 degrees east longitude covers an area approximately 300
by 300 kilometers (186 by 186 miles) at the northern end of Maxwell Montes,
the tallest mountain belt on Venus at approximately 10 kilometers (6.2
miles) above the average elevation on the planet.  An anaglyph is a type of
image consisting of two data sets slightly displaced from one another and
projected in red and blue so that a 3-dimensional or stereo effect is
produced when the image is viewed through red and blue tinted glasses.  The
images were obtained when Magellan "looked" at the same part of the surface
from different incidence angles during its first and third mapping cycles
(October 1990 and February 1992, respectively).  The ability to see both
the radar image and differences in elevation together is valuable for
geologic interpretation.  The two broad valleys, crossing through the
center of the image are not visible in the 2-dimensional radar images.
Likewise, the image reveals that Maxwell Montes, which trends approximately
northwest is cut by northeast trending mountains in the upper, left portion
of the image, indicating that the latter are younger.  It is also apparent
from this image that the anomalously bright terrain which scientists are
attempting to understand does not occur at or greater than a specific
elevation although it generally occurs at high altitudes.  The image was
produced at the JPL Multimission Image Processing Laboratory.
                          MAGELLAN PROJECT OFFICE

                                  P-40160
                                  5/4/92

This Magellan full-resolution mosaicked anaglyph centered at 65 degrees
north latitude, 0.0 degrees east longitude covers an area approximately 614
by 537 kilometers (381 by 333 miles) where the smooth, elevated plains of
Lakshmi Planum (on the left portion of the image) meet Maxwell Montes, the
tallest mountain belt on Venus at approximately 10 kilometers (6.2 miles)
above the average elevation on the planet.  An anaglyph is a type of image
consisting of two data sets slightly displaced from one another and
projected in red and blue so that a 3-dimensional or stereo effect is
produced when the image is viewed through red and blue tinted glasses.  The
images were obtained when Magellan "looked" at the same part of the surface
from different incidence angles during its first and third mapping cycles
(October 1990 and February 1992, respectively).  The ability to see both
the radar image and differences in elevation together is valuable for
geologic interpretation.  The broad valleys, in the upper, center portion
of the image are not visible in the 2-dimensional radar images.  Likewise,
the image reveals that Maxwell Montes, which trends approximately northwest
is cut by northeast trending mountains in the top, left portion of the
image, indicating that the latter are younger.  It is also apparent from
this image that the anomalously bright terrain which scientists are
attempting to understand does not occur at or greater than one specific
"cutoff" elevation although it generally occurs at high altitudes.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109

PHOTO CAPTION                           MAGELLAN
                                        P-40175  MGN-97
                                        April 22, 1992

Maat Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  The viewpoint is located 634
kilometers (393 miles) north of Maat Mons at an elevation of 3 kilometers
(2 miles) above the terrain.  Lava flows extend for hundreds of kilometers
across the fractured plains shown in the foreground, to the base of Maat
Mons.  The view is to the south with the volcano Maat Mons appearing at the
center of the image on the horizon and rising to almost 5 kilometers (3
miles) above the surrounding terrain.  Maat Mons, is located at
approximately 0.9 degrees north latitude, 194.5 degrees east longitude with
a peak that ascends to 8 kilometers (5 miles) above the mean surface.  Maat
Mons is named for an Egyptian Goddess of truth and justice.  Magellan
synthetic aperture radar data is combined with radar altimetry to develop a
three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 10 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.
Simulated color and a digital elevation map developed by the U. S.
Geological Survey, are used to enhance small-scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced by the Solar System
Visualization project and the Magellan Science team at the JPL Multimission
Image Processing Laboratory and is a single frame from a video released at
the April 22, 1992 news conference.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40176  MGN-98
                                        April 22, 1992

Sapas Mons is displayed in the center of this computer-generated three-
dimensional perspective view of the surface of Venus.  The viewpoint is
located 527 kilometers (327 miles) northwest of Sapas Mons at an elevation
of 4 kilometers (2.5 miles) above the terrain.  Lava flows extend for
hundreds of kilometers across the fractured plains shown in the foreground
to the base of Sapas Mons.  The view is to the southeast with Sapas Mons
appearing at the center with Maat Mons located in the background on the
horizon.  Sapas Mons, a volcano 400 kilometers (248 miles) across and 1.5
kilometers (0.9 mile) high is located at approximately 8 degrees north
latitude, 188 degrees east longitude, on the western edge of Atla Regio.
Its peak sits at an elevation of 4.5 kilometers (2.8 miles) above the
planet's mean elevation.  Sapas Mons is named for a Phoenician Goddess.
The simulated hues are based on color images recorded by the Soviet Venera
13 and 14 spacecraft.  The vertical scale in this perspective has been
exaggerated 10 times.  Rays cast in a computer intersect the surface to
create a three-dimensional perspective view.  Simulated color and a digital
elevation map developed by the U. S. Geological Survey, are used to enhance
small-scale structure.  The simulated hues are based on color images
recorded by the Soviet Venera 13 and 14 spacecraft.  The image was produced
by the Solar System Visualization project and the Magellan Science team at
the JPL Multimission Image Processing Laboratory and is a single frame from
a video released at the April 22, 1992 news conference.
                          MAGELLAN PROJECT OFFICE

                                  P-40255
                                  6/1/92

Maat Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  This image was created on
Caltech's Intel Touchstone Delta Supercomputer.  The viewpoint is located
634 kilometers (393 miles) north of Maat Mons at an elevation of 3
kilometers (2 miles) above the terrain.  Lava flows extend for hundreds of
kilometers across the fractured plains shown in the foreground, to the base
of Maat Mons.  The view is to the south with the volcano Maat Mons
appearing at the center of the image on the horizon and rising to almost 5
kilometers (3 miles) above the surrounding terrain.  Maat Mons is located
at approximately 0.9 degrees north latitude, 194.5 degrees east longitude
with a peak that ascends to 8 kilometers (5 miles) above the mean surface.
Maat Mons is named for an Egyptian Goddess of truth and justice.  Magellan
synthetic aperture radar data is combined with radar altimetry to develop a
three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 10 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.
Simulated color and a digital elevation map developed by the U.S.
Geological Survey are used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced by the Solar System Visualization
project and the Magellan Science Team at the JPL Multimission Image
Processing Laboratory and is a single frame from a video being created on
the Delta Supercomputer.  This work is part of NASA's "Grand Challenge"
research effort in the planetary science applications of high performance
computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40256
                                  6/1/92

Sapas Mons is displayed in the center of this computer-generated three-
dimensional perspective view of the surface of Venus.  This image was
created on Caltech's Intel Touchstone Delta Supercomputer.  The viewpoint
is located 527 kilometers (327 miles) northwest of Sapas Mons at an
elevation of 4 kilometers (2.5 miles) above the terrain.  Lava flows extend
for hundreds of kilometers across the fractured plains shown in the
foreground to the base of Sapas Mons.  The view is to the southeast with
Sapas Mons appearing at the center with Maat Mons located in the background
on the horizon.  Sapas Mons, a volcano 400 kilometers (248 miles) across
and 1.5 kilometers (0.9 miles) high is located at approximately 8 degrees
north latitude, 188 degrees east longitude, on the western edge of Atla
Regio.  Its peak sits at an elevation of 4.5 kilometers (2.8 miles) above
the planet's mean elevation.  Sapas Mons is named for a Phoenician goddess.
The vertical scale in this perspective has been exaggerated 10 times.  Rays
cast in a computer intersect the surface to create a three-dimensional
perspective view.  Simulated color and a digital elevation map developed by
the U.S. Geological Survey are used to enhance small-scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced by the Solar System
Visualization project and the Magellan Science Team at the JPL Multimission
Image Processing Laboratory and is a single frame from a video being
created on the Delta Supercomputer.  This work is part of NASA's "Grand
Challenge" research effort in the planetary science applications of high
performance computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40257
                                  6/1/92

Sapas Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  This image was created on
Caltech's Intel Touchstone Delta Supercomputer.  The viewpoint is located
243 kilometers (151 miles) south of Sapas Mons.  Lava flows extend for
hundreds of kilometers from the large volcano into the smooth plains.  The
view is to the north with the volcano Sapas Mons appearing at the center of
the image at approximately 0.9 degrees north latitude, 188 degrees east
longitude with two peaks that ascend to 3 kilometers (1.8 miles) above the
mean surface.  Sapas Mons is named after an ancient Phoenician Goddess.
Magellan synthetic aperture radar data is combined with radar altimetry to
develop a three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 10 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.
Simulated color and a digital elevation map developed by the U.S.
Geological Survey are used to enhance small-scale structure.  The simulated
hues are based on color images recorded by the Soviet Venera 13 and 14
spacecraft.  The image was produced by the Solar System Visualization
project and the Magellan Science Team at the JPL Multimission Image
Processing Laboratory and is a single frame from a video being created on
the Delta Supercomputer.  This work is part of NASA's "Grand Challenge"
research effort in the planetary science applications of high performance
computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40258
                                  6/1/92

The great volcanos of Atla Regio, Sapas, Maat and Ozza Montes are displayed
in this computer generated three-dimensional perspective view of the
surface of Venus.  This image was created on Caltech's Intel Touchstone
Delta Supercomputer.  The viewpoint is located on the flank of Sapas Mons,
1216 kilometers (754 miles) northwest of Maat Mons, which is in the center
of the image on the horizon, towering above the plains at an elevation of 8
kilometers (5 miles).  Lava flows extend for hundreds of kilometers across
the smooth plains from the margins of the volcanoes.  The view is to the
southeast with Maat Mons located at approximately 0.9 degrees north
latitude, 194.5 degrees east longitude and Sapas at 9 degrees north
latitude, 188 degrees east longitude.  Sapas Mons is named after an ancient
Phoenician goddess, while the name Maat comes from an Egyptian Goddess of
truth and justice.  Magellan synthetic aperture radar data is combined with
radar altimetry to develop a three-dimensional map of the surface.  The
vertical scale in this perspective has been exaggerated 10 times.  Rays
cast in a computer intersect the surface to create a three-dimensional
perspective view.  Simulated color and a digital elevation map developed by
the U.S. Geological Survey are used to enhance small-scale structure.  The
simulated hues are based on color images recorded by the Soviet Venera 13
and 14 spacecraft.  The image was produced by the Solar System
Visualization project and the Magellan Science Team at the JPL Multimission
Image Processing Laboratory and is a single frame from a video being
created on the Delta Supercomputer.  This work is part of NASA's "Grand
Challenge" research effort in the planetary science applications of high
performance computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40286  MGN-99
                                        May 29, 1992

This image, with radar illumination from west to east, shows three unusual
volcanoes located in the Guinevere Planitia lowland.  At the center of the
image is a large feature (50 kilometers or 31 miles in diameter) with an
unusual shape: very round when viewed from above with steep-sides and a
flat top.  These volcanoes are believed to be the result of relatively
thick and sticky (viscous) lava flows that originated from a point source.
Although a faint remnant of its original circular shape is preserved, the
northern rim of this central volcano has a steep scarp.  The scarp is
probably the result of material that has slid away from the volcano and
subsequently has been covered by lava flows.  This volcano overlaps another
feature to the southwest that is about 45 kilometers (28 miles) in diameter
and disrupted by many fractures.  The southeastern volcano (25 kilometers
or 15.5 miles in diameter) appears to be the highest of the three as its
illuminated western edge has the brightest radar return.  The scalloped
edges give this feature a bottle-cap like appearance.  The highly scalloped
edges are probably the result of multiple material slides along the volcano
margin.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40287  MGN-100
                                        May 29, 1992

The Magellan spacecraft has observed remnant landslide deposits apparently
resulting from the collapse of volcanic structures.  This Magellan radar
image is centered about 25.4 degrees south latitude and 308 degrees east
longitude in the Southwestern Navka Region of Venus.  The image shows a
17.4 kilometer (10.8 mile) diameter volcanic dome on the plains.  The dome
is approximately 1.86 kilometers (1.2 mile) in height and it has a slope of
about 23 degrees.  The northwest and northeast flanks of the dome have
collapsed to form landslides that have deposited debris on the plains.  The
image shows an area 110 kilometers (68 miles) across and 100 kilometer (62
miles) in length.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40288  MGN-101
                                        May 29, 1992

The Magellan spacecraft has observed remnant landslide deposits apparently
resulting from the collapse of volcanic structures.  This image, centered
at 45.2 degrees south latitude, 201.4 degrees east longitude, shows a
collapse deposit 70 kilometers (43 miles) across.  The bright, highly
textured deposit near the center of the image probably consists of huge
blocks of fractured volcanic rock, many as large as several hundred meters
across.  A remnant of the volcano itself, about 20 kilometers (12.4 miles)
across, is seen at the center of the image.  The distorted radar appearance
of the volcano is a result of extremely steep slopes on the "scars" from
which the landslide material originated.  A field of numerous small
volcanic domes can be seen in the northern half of the image.  The bright
irregular lineaments trending to the north-northwest are ridges caused by
regional tectonic deformation of the upper layers of the Venusian crust.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40289  MGN-102
                                        May 29, 1992

This Magellan full-resolution mosaic which covers an area 143 by 146
kilometers (89 by 91 miles) is centered at 55 degrees north latitude, 266
degrees east longitude.  The bright feature, slightly south of center is
interpreted to be a volcano, 15-20 kilometers (9.3 to 12.4 miles) in
diameter with a large apron of blocky debris to its right and some smaller
aprons to its left.  A preferred explanation is that several massive,
catastrophic landslides dropped down steep slopes and were carried by their
momentum out into the smooth, dark lava plains.  At the base of the east-
facing or largest scallop on the volcano is what appears to be a large
block of coherent rock, 8-10 kilometers (5 to 6 miles) in length.  The
similar margin of both the scallop and block and the shape in general is
typical of terrestrial slumped blocks (masses of rock which slide and
rotate down a slope instead of breaking apart and tumbling).  The bright
lobe to the south of the volcano may either be a lava flow or finer debris
from other landslides.  This volcanic feature, characterized by its
scalloped flanks is part of a class of volcanos called scalloped or
collapsed domes of which there are more than 80 on Venus.  Based on the
chute-like shapes of the scallops and the existence of a spectrum of
intermediate to well defined examples, it is hypothesized that all of the
scallops are remnants of landslides even though the landslide debris is
often not visible.  Possible explanations for the missing debris are that
it may have been covered by lava flows, the debris may have weathered or
that the radar may not be recognizing it either because the individual
blocks are too small.
                          MAGELLAN PROJECT OFFICE

                                  P-40333
                                  6/1/92

Hyppolyta Linea, a system of surface fractures in the Lavinia region of
Venus, is shown in this false-color Magellan radar image.  The area
pictured is 325 kilometers by 360 kilometers (202 miles by 223 miles) and
is centered at 41 degrees south latitude, 340 degrees east longitude.  The
fracture belt sits somewhat higher in elevation (about 1 kilometer or 0.62
mile) than the surrounding volcanic plains, and is dominated by sets of
fault-bounded valleys known as graben.  The trend of most of these
fractures is perpendicular to sets of narrow sinuous features called
"wrinkle ridges" that are seen in the plains at the top and bottom of the
image.  Similar wrinkle ridges have been identified on the surfaces of the
Moon, Mars and Mercury.  They are believed to be the result of horizontal
compressional forces in the uppermost layers of the planets' crusts.  The
inter-relationships between the compression-related wrinkle ridges and the
likely extension-related graben structures allow geologists to unravel the
tectonic history of this region of the surface of Venus.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40347
                                  6/15/92

These images display the distribution of radio-thermal emission efficiency
(emissivity) over the Venus surface, observed using the Magellan SAR radar
receiver.  Color is used to code the emission efficiency (see color bar).
Red corresponds to the highest, blue to the lowest values of emissivity.
The upper image shows that part of the planet between 69 degrees north and
69 degrees south latitude in Mercator projection; beneath it are the two
polar regions covering latitudes above 44 degrees in stereographic
projection.  Easterly longitudes run across the Mercator map from left to
right, and around the periphery of the polar stereographic projections.
The emissivity of the surface is determined primarily by its bulk
electrical properties and on the angle at which the emitted radiation is
viewed.  The decrease in average emissivity at low latitudes results from
the higher view angle there.  The horizontal resolution also varies with
latitude, being determined solely by the "footprint" of Magellan's high-
gain SAR antenna beam.

Near the equator the surface resolution is about 20 kilometers, but at high
latitudes it degrades to as much as 100 kilometers.

There is a tendency for elevated regions, e.g. the Maxwell Montes (left of
the data gap at top left center) and Aphrodite Terra (along the equator at
right center), to show lower values of emissivity than are typical of
lower-lying areas.  These low values confirm the high values of radar
reflectivity seen in corresponding regions by the Magellan altimeter, but
do not offer significant additional information to help solve the
considerable puzzle of what mechanism may underlie this unexpected
behavior.  On a cooler planet such as Earth or Mars, water or ice might
explain the anomalous observations, but at the 470-degree-Celsius
temperature of the Venus surface, neither can be present.  Some theories
require the presence of minerals such as iron pyrites; others suggest a
material, as yet unidentified, that has extremely low electrical loss.  The
data shown here were analyzed and projected at the Center for Space
Research, Massachusetts Institute of Technology.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40348
                                  6/15/92

These images show the distribution of radar reflection coefficient
(reflecting efficiency) of the Venus surface when viewed from directly
overhead by the Magellan altimeter.  The lightest shades locate areas
having the highest values of normal-incidence reflectivity (as high as 70
percent in places), while darker shades indicate areas of low reflection
efficiency.  The upper image shows that part of the planet between 69
degrees north and 69 degrees south latitude in Mercator projection; beneath
it are the two polar regions covering latitudes above 44 degrees in
stereographic projection.  Easterly longitudes run across the Mercator map
from left to right, and around the periphery of the polar stereographic
projections.  Resolution of the surface varies with spacecraft altitude,
being about 10 kilometers near the equator and degrading to as much as 25
kilometers at high latitudes.  Black areas indicate where data had not yet
been obtained by Magellan after the first eight months of operation.

There is a tendency for elevated regions, e.g. the Maxwell Montes (left of
the data gap at top center) and Aphrodite Terra (along the equator at
right), to show higher values of reflectivity than are typical of lower-
lying areas.  The highest values (greater than 30 percent) are puzzling to
understand.  On a cooler planet such as Earth or Mars, water or ice might
explain the observations, but at the 470-degree-Celsius temperature of the
Venus surface, neither can be present.  Some theories require the presence
of minerals such as iron pyrites; others suggest a material, as yet
unidentified, that has extremely low electrical loss.  The data shown here
were analyzed and projected at the Center for Space Research, Massachusetts
Institute of Technology.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40657
                                  7/22/92

This Magellan synthetic aperture radar (SAR) mosaic is a sinusoidal equal-
area projection of Venus.  Centered at 180 degrees latitude, the image
includes all information gathered by the spacecraft from the beginning of
the mission in September, 1990 through July, 1991.  A sinusoidal equal-area
projection distorts the true shapes of features while allowing an unbiased
view of the sizes of features whether they are on the equator or near the
poles.  While the planet rotates underneath the spacecraft, Magellan
collects successive swaths of data, approximately 25 kilometers (16 miles)
in width but tens of thousands of kilometers or miles in length.  After
Venus has rotated one full Venusian day or 243 Earth days, the spacecraft
completes its passage over the entire surface.  Represented in this image
is the sum total of the information from Magellan's 'first passage'
referred to as 'Cycle 1,' along with one major gap fill from Cycle 2.  The
solid black regions are gaps in the data set primarily due to spacecraft
and/or planetary geometry constraints.  For example, we could not receive
information from Magellan during Superior Conjunction, when the spacecraft
was on the other side of the Sun from the Earth.  This image was produced
by Washington University, St. Louis, Missouri.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40686 (B,C)  MGN-103
                                        August 11, 1992

This Magellan full-resolution mosaic of Venus, centered at 10 degrees north
latitude, 301 degrees east longitude shows an area replete with diverse
volcanic features.  The image of an area 489 kilometers long by 311
kilometers wide (303 by 193 miles), is dominated by volcanic plains which
appear mottled because of varying roughnesses of each solidified lava flow.
The rougher the terrain the brighter it appears in the radar image.  The
small, bright bumps clustered in the left portion of the image are a
grouping of small volcanoes called a shield field.  Each shield volcano is
approximately 2 to 5 kilometers (1.2 to 3.1 miles) in diameter and has very
subdued relief.  It is believed that the lava flows that make up each
shield originates from a common source.  To the right of the shield field
is another type of volcano called a scalloped dome.  It is 25 kilometers
(16 miles) in diameter and has a central pit.  Some of the indistinct lobe-
shaped pattern around the dome may either be lava flows or rocky debris
which has fallen from the scalloped cliffs surrounding the domes.  The
small radial ridges characteristic of scalloped domes are remnants of
catastrophic landslides.  To the right of that feature is a large
depression called a volcanic caldera.  The caldera was formed when lava was
expelled from an underground chamber, which when emptied, subsequently
collapsed, forming the depression.  The feature furthest to the east
(right) is another scalloped dome, 35 kilometers (22 miles).  That feature
is unusual in that lava came out through the southeastern margin, rafting a
large portion of the dome for 20 kilometers (12 miles).  The lava continues
into the lower right portion of the area in the image.  Its steep rounded
boundaries suggest it was a very sticky, oozing lava.  That same type of
lava is what scientists propose formed the steep-sided domes such as the
bright, round feature, slightly northeast of center.  It is highly likely
that the features are all part of a single volcanic complex, where a large
body of molten rock formed beneath the surface feeding each of the
volcanoes above.  The presence of fractures in the west, partially
surrounding the volcanoes supports this theory.
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40690  MGN-104
                                        August 11, 1992

This full resolution Magellan radar mosaic centered at 14 degrees north
latitude, 72 degrees east longitude, shows an oblique view of the impact
crater Riley, named for Margaretta Riley, a 19th century botanist.  This
view was prepared from two left-looking Magellan radar images acquired with
different incidence angles.  Because the relief displacements on the two
images are different, depths from the crater rim to the crater floor and
heights of the crater rim and flanks above the surrounding plains can be
measured.  The crater is 25 kilometers (15.5 miles) in diameter.  The floor
of the crater is 580 meters (1914 feet) below the plains surrounding the
crater.  The crater's rim rises 620 meters (2046 feet) above the plains and
1200 meters (3960 feet) above the crater floor.  The crater's central peak
is 536 meters (1769 feet) tall.  The crater's diameter is 40 times the
depth resulting in a relatively shallow appearance.  The topography is
exaggerated by 22 times to emphasize the crater's features.  This oblique
view was produced from two left-looking radar stereo image mosaics
utilizing photogrammetric software developed by the Solar System
Visualization Project and the Digital Image Animation Laboratory at the Jet
Propulsion Laboratory's Multimission Image Processing Laboratory.
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40691  MGN-105
                                        August 11, 1992

This set of three Magellan images shows a small volcano, lava plains
distorted into "wrinkle ridges," and some unusual wispy-appearing surface
deposits.  The images were acquired during the first, second, and third
mapping cycles of the mission, in March,1991, November 1991, and July 1992,
respectively.  The area shown is about 400 kilometers by 100 kilometers
(248 miles by 62 miles) and is centered near 47.5 degrees south latitude,
226 degrees east longitude, in the Imdr region of Venus.  The middle image,
from the second cycle, was acquired with the spacecraft facing toward the
west (left), while the other two images were acquired with an identical
east-looking geometry.  The differing appearance of the second image has
intrigued Magellan scientists, because of the possibility that the bright
patches observed in cycle 2 may have been caused by rearrangement of loose
soil material between March and November 1991.  However, by duplicating the
cycle 1 viewing geometry in cycle 3, the surface change theory has been
tentatively ruled out.  Instead, the radar brightness variations are
attributed to reflections from an undulating surface, such as sand ripples
or small dunes, that have an asymmetry in the east-west direction.  The
deposits are apparently associated with a 78 kilometers (48 miles) diameter
impact crater, Stowe, which lies about 500 kilometers (310 miles) to the
northeast.  The fine-grained material created during the impact event may
have settled out to form the unusual surface deposits observed here.
Scientists are now trying to determine if the proposed ripple structures
formed at the time of the impact, or are the result of ongoing wind action
at the surface.  Data quality during portions of cycle 3 was adversely
affected by a faulty transmitter aboard the spacecraft, leading to the
missing strips in the bottom image.
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40697  MGN-106
                                        August 11, 1992

This computer-generated perspective view of Latona Corona and Dali Chasma
on Venus shows Magellan radar data superimposed on topography.  The view is
from the northeast and vertical exaggeration is 10 times.  Exaggeration of
relief is a common tool scientists use to detect relationships between
structure (i.e., faults and fractures) and topography.  Latona Corona, a
circular feature approximately 1000 kilometers or (620 miles) in diameter
whose eastern half is shown at the left of the image, has a relatively
smooth, radar-bright raised rim.  Bright lines or fractures within the
corona appear to radiate away from its center toward the rim.  The rest of
the bright fractures in this area are associated with the relatively deep
(approximately 3 kilometers or 1.9 miles) troughs of Dali Chasma.  The Dali
and Diana Chasma system consist of deep troughs that extend for 7,400
kilometers (4,588 miles) and are very distinct features on Venus.  These
chasma connect the Ovda and Thetis highlands with the large volcanoes at
Atla Regio and thus are considered to be the "Scorpion Tail" of Aphrodite
Terra.  The broad, curving scarp resembles some of Earth's subduction zones
where crustal plates are pushed over each other.  The radar bright surface
at the highest elevation along the scarp is similar to surfaces in other
elevated regions where some metallic mineral such as pyrite (fool's gold)
may occur on the surface.
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-40698  MGN-107
                                        August 11, 1992

This Magellan mosaic centered at 12.5 degrees south latitude, 261 degrees
east longitude, shows an unnamed volcano that straddles a narrow, angular
fracture system extending southeastward from Phoebe Regio, a highland
tessera, or tile-appearing, region.  The image, which shows an area
approximately 587 kilometers (364 miles) on a side, is a synthetic aperture
radar (SAR) backscatter image combined with a color radio-thermal emission
(emissivity) image.  The red corresponds to a high emissivity, blue to a
low emissivity.  The emissivity, which is a measure of the electrical
properties of surface materials, is an important clue for understanding
surface composition.  While many Magellan images display just the radar
backscatter in order to obtain information about the shape and roughness of
features, there are other important data sets including the surface
topography obtained from the Magellan altimeter and the emissivity.
Information to derive emissivity is recorded when Magellan's radar antenna
ceases to send signals to the surface and instead listens to the radio
waves naturally emitted from the surface.  This volcano exhibits what
scientists have noticed to be a widespread phenomenon on Venus -- the
occurrence of lower emissivities at higher altitudes.  The summit of the
volcano, which is about 2 kilometers (1.2 miles) in height, displays the
lowest emissivity, while the emissivity becomes progressively greater
toward lower elevations.  The presence of minerals such as pyrrohtite or
pyrite may explain the low emissivities in some cases because of their
electrical properties and their stability at the temperatures and pressures
found at high altitudes on Venus.  The image was produced at the JPL
Multimission Image Processing Laboratory.
                          MAGELLAN PROJECT OFFICE

                                  P-40699
                                  8/14/92

Maat Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  This image was created on
Caltech's Intel Touchstone Delta Supercomputer.  The viewpoint is located
near the face of Maat Mons.  The view is to the east with the volcano Maat
Mons appearing at the center of the image on the horizon.  Maat Mons is
located at approximately 0.9 degrees north latitude, 194.5 degrees east
longitude with a peak that ascends to 8 kilometers (5 miles) above the mean
surface.  Maat Mons is named for an Egyptian Goddess of truth and justice.
Magellan synthetic aperture radar data is combined with radar altimetry to
develop a three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 10 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.  A
digital elevation map developed by the U.S. Geological Survey is used to
enhance small-scale structure.  The image was produced by the Solar System
Visualization project, the Magellan Science Team at the JPL Multimission
Image Processing Laboratory and the Digital Image Animation Laboratory, and
is a single frame from a video being created on the Delta Supercomputer.
This work is part of NASA's "Grand Challenge" research effort in the
planetary science applications of high performance computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40700
                                  8/14/92

Maat Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  This image was created on
Caltech's Intel Touchstone Delta Supercomputer.  The viewpoint is located
634 kilometers (393 miles) north of Maat Mons at an elevation of 3
kilometers (2 miles) above the terrain.  Lava flows extend for hundreds of
kilometers across the fractured plains shown in the foreground, to the base
of Maat Mons.  The view is to the south with the volcano Maat Mons
appearing at the center of the image on the horizon and rising to almost 5
kilometers (3 miles) above the surrounding terrain.  Maat Mons is located
at approximately 0.9 degrees north latitude, 194.5 degrees east longitude
with a peak that ascends to 8 kilometers (5 miles) above the mean surface.
Maat Mons is named for an Egyptian Goddess of truth and justice.  Magellan
synthetic aperture radar data is combined with radar altimetry to develop a
three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 10 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.  A
digital elevation map developed by the U.S. Geological Survey is used to
enhance small-scale structure.  The image was produced by the Solar System
Visualization project, the Magellan Science Team at the JPL Multimission
Image Processing Laboratory and the Digital Image Animation Laboratory, and
is a single frame from a video being created on the Delta Supercomputer.
This work is part of NASA's "Grand Challenge" research effort in the
planetary science applications of high performance computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40701
                                  8/14/92

Sapas Mons is displayed in this computer generated three-dimensional
perspective view of the surface of Venus.  This image was created on
Caltech's Intel Touchstone Delta Supercomputer.  The viewpoint is located
243 kilometers (151 miles) south of Sapas Mons.  Lava flows extend for
hundreds of kilometers from the large volcano into the smooth plains.  The
view is to the north with the volcano Sapas Mons appearing at the center of
the image at approximately 0.9 degrees north latitude, 188 degrees east
longitude with two peaks that ascend to 3 kilometers (1.8 miles) above the
mean surface.  Sapas Mons is named after an ancient Phoenician Goddess.
Magellan synthetic aperture radar data is combined with radar altimetry to
develop a three-dimensional map of the surface.  The vertical scale in this
perspective has been exaggerated 10 times.  Rays cast in a computer
intersect the surface to create a three-dimensional perspective view.  A
digital elevation map developed by the U.S. Geological Survey is used to
enhance small-scale structure.  The image was produced by the Solar System
Visualization project, the Magellan Science Team at the JPL Multimission
Image Processing Laboratory and the Digital Image Animation Laboratory, and
is a single frame from a video being created on the Delta Supercomputer.
This work is part of NASA's "Grand Challenge" research effort in the
planetary science applications of high performance computers.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40752
                                  1/12/93

This perspective view of the synthetic aperture radar (SAR) image of part
of Bereghinya Planitia is false-colored to show the thermal emissivity (the
amount of energy radiated by the surface at a given temperature, relative
to the maximum amount for a perfect radiator).  Emissivity varies somewhat
for different rock types, and is more strongly affected by the small-scale
surface texture: rougher, more porous surfaces tend to have higher
emissivities.  In this image purple represents an emissivity of 0.81, and
red an emissivity of 0.88.  The base image is a compressed once mosaicked
image data record (C1-MIDR) which is a standard Magellan data product with
a resolution of 0.255 kilometer/pixel, processed to enhance small features.
The Magellan altimeter dataset was used to determine the shape, and thus
the appearance in perspective, of the surface.  Shading based on the
altimetric shape (with illumination from the right in this view) was also
added to the image in order to emphasize large-scale topographic features.
The view is from approximately 33.88 degrees north latitude, 18.80 degrees
east longitude, looking due west along a chain of arachnoids, "spider-like"
features that have raised rims surrounding a central depression and are
characterized by both concentric and radiating patterns of bright
fractures.  The bright feature in the foreground is a lava flow.  The image
has been vertically exaggerated by a factor of 20.  Image processing was
performed for the Magellan project by the U.S. Geological Survey,
Flagstaff, Arizona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40753
                                  1/12/93

This synthetic aperture radar (SAR) image of part of Bereghinya Planitia is
false-colored to show altimetry data.  Purple represents a radius of
6050.35 kilometers from the center of Venus, and red a radius of 6052.65
kilometers (the mean radius of the planet is 6051.8 kilometers).
Geologically, this area consists of lowland lava plains, criss-crossed by
chains of arachnoids.  These "spider-like" features have raised rims
surrounding a central depression and are characterized by both concentric
and radiating patterns of bright fractures.  A regional upward slope to the
north is apparent.  The base image is a compressed once mosaicked image
data record (C1-MIDR) which is a standard Magellan data product with a
resolution of 0.225 kilometer/pixel and is in a sinusoidal equal-area map
projection. This image, centered at 45 degrees north latitude, 11 degrees
east longitude, is 1613 kilometers from top to bottom and 1843 kilometers
from side to side.  The base image has been digitally processed to enhance
small features.  The intensity (brightness) information in the SAR image
has been preserved, but color has been added to indicate the variation of
elevations mapped by the Magellan altimeter.  Image processing was
performed for the Magellan project by the U.S. Geological Survey,
Flagstaff, Arizona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40754
                                  1/12/93

This synthetic aperture radar (SAR) image of part of Aphrodite Terra is
false-colored to show the thermal emissivity (the amount of energy radiated
by the surface at a given temperature, relative to the maximum amount for a
perfect radiator).  Purple represents an emissivity of 0.50, and red an
emissivity of 0.89.  Emissivity varies somewhat for different rock types,
and is strongly affected by small scale surface texture: rougher, more
porous surfaces tend to have higher emissivities.  These relatively subtle
effects are swamped by an abrupt decrease in emissivity at high elevations
(greater than about 6054 kilometers from the center of the planet) almost
everywhere on Venus.  This decrease is believed to be due to the reaction
of rocks in high, relatively cool locations with the atmosphere, forming a
highly conductive mineral phase.  The base image is a compressed once
mosaicked image data record (C1-MIDR) which is a standard Magellan data
product with a resolution of 0.225 kilometer/pixel and is in a sinusoidal
equal-area projection.  This image, centered at 15 degrees south latitude,
129 degrees east longitude, is 1613 kilometers from top to bottom and 1843
kilometers from side to side.  The base image has been digitally processed
to enhance small features.  The southern edge of Aphrodite Terra, a
continent-sized region of highlands centered on the Venusian equator, runs
roughly horizontally across the center of the image.  This highland is made
up principally of complex ridged terrain (formerly called tesserae, because
of their resemblance to an inlaid parquet floor) that is believed to have
been formed by extensive crustal deformation.  Image processing was
performed for the Magellan Project by the U.S. Geological Survey,
Flagstaff, Arizona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40755
                                  1/12/93

This synthetic aperture radar (SAR) image of part of Aphrodite Terra is
false-colored to show variations in meter scale roughness of the surface.
This dataset is sensitive to slopes that extend over distances larger than
the radar wavelength (tens of centimeters) but smaller than the area
sampled by the instrument (tens of kilometers).  In this image, purple
represents a typical or root-mean-square (RMS) slope of 3.0 degrees, and
red a RMS slope of 19.2 degrees.  The greater roughness of the highlands
compared to the lowland plains is readily apparent.  The base image is a
compressed once mosaicked image data record (C1-MIDR) which is a standard
Magellan data product with a resolution of 0.225 kilometer/pixel and is in
a sinusoidal equal-area projection.  This image, centered at 15 degrees
south latitude, 129 degrees east longitude, is 1613 kilometers from top to
bottom and 1843 kilometers from side to side.  The base image has been
digitally processed to enhance small features.  The southern edge of
Aphrodite Terra, a continent-sized highland centered on the Venusian
equator, runs roughly horizontally across the center of the image.  This
highland is made up principally of complex ridged terrain (formerly called
tesserae, because of their resemblance to an inlaid parquet floor) and is
believed to have been formed by extensive crustal deformation.  To the
south are lowland plains that are made up of overlapping lava flows.  Image
processing was performed for the Magellan Project by the U.S. Geological
Survey, Flagstaff, Arizona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40756
                                  1/12/93

This synthetic aperture radar (SAR) image of part of Aphrodite Terra is
false-colored to show variations in elevation.  Purple represents a radius
of 6051.7 kilometers from the center of Venus and red a radius of 6055.7
kilometers (the mean radius of the planet is 6051.8 kilometers).  This
image clearly shows the difference in elevation between the lowland plains
in the south and the highlands to the north.  A rift is located along the
boundary between these two terrains.  The base image is a compressed once
mosaicked image data record (C1-MIDR) which is a standard Magellan data
product with a resolution of 0.225 kilometer/pixel and is in a sinusoidal
equal-area projection.  This image, centered at 15 degrees south latitude,
129 degrees east longitude, is 1613 kilometers from top to bottom and 1843
kilometers from side to side.  The base image has been digitally processed
to enhance small features.  The southern edge of Aphrodite Terra, a
continent-sized highland centered on the Venusian equator, runs roughly
horizontally across the center of the image.  This highland is made up
principally of complex ridged terrain (formerly called tesserae, because of
their resemblance to an inlaid parquet floor) and is believed to have been
formed by extensive crustal deformation.  The lowland plains are made up of
overlapping lava flows.  Image processing was performed for the Magellan
Project by the U.S. Geological Survey, Flagstaff, Arizona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40757
                                  1/12/93

This synthetic aperture radar (SAR) image of part of Maxwell Montes and
Fortuna Tesserae is false-colored to show the thermal emissivity (the
amount of energy radiated by the surface at a given temperature, relative
to the maximum amount for a perfect radiator).  Purple represents the
lowest values (an emissivity of 0.40) and red the highest values (an
emissivity of 0.90).  Emissivity varies somewhat for different rock types,
and is strongly affected by small scale surface texture: rougher, more
porous surfaces tend to have higher emissivities.  These relatively subtle
effects are swamped by the abrupt decrease in emissivity at high elevations
(greater than about 6054 kilometers from the center of the planet) almost
everywhere on Venus.  This decrease is believed to be due to the reaction
of rocks in high, relatively cool locations with the atmosphere, forming a
highly conductive mineral phase.  The base image is a full resolution basic
image data record (F-MIDR) which is a standard Magellan data product with a
resolution of 0.075 kilometer/pixel and is in a sinusoidal equal-area
projection.

This image, centered at 66 degrees north latitude, 12 degrees east
longitude, is 538 kilometers from top to bottom and 614 kilometers from
side to side.  The base image has been digitally processed to enhance small
features.  Maxwell Montes, the highest mountain range on Venus, occupies
approximately the left most one-third of the image, with its summit just
outside the area shown.  The remainder of the image covers part of Fortuna
Tesserae, a region of complex ridged terrain that is believed to have been
formed by extensive deformation of the Venusian crust.  In the left center
of the image is the 105-kilometer diameter crater Cleopatra.  Prior to the
Magellan mission, it was not clear whether Cleopatra was an impact crater
or a volcano; a thin channel can be seen leading from the inner crater to a
lava-flooded area to the east, but this is now believed to be the result of
impact-triggered melting rather than volcanism.  The impact nature of
Cleopatra is clearly demonstrated by its ejecta, which partially blanket
the ridges in the nearby terrain.  Image processing was performed for the
Magellan Project by the U.S. Geological Survey, Flagstaff, Arizona.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-40844
                                  9/8/92

This Magellan mosaic centered at 12.5 degrees south latitude, 261 degrees
east longitude, shows an unnamed volcano that straddles a narrow, angular
fracture system extending southeastward from the Phoebe Regio highlands.
The image, which shows an area approximately 587 kilometers (364 miles) on
a side, is a synthetic aperture radar (SAR) backscatter image.  While
Magellan SAR images obtain information about the shape and roughness of
features, there are other important data sets including the surface
topography obtained from the Magellan altimeter and the emissivity.  This
volcano exhibits what scientists have noticed to be a widespread phenomenon
on Venus -- the occurrence of lower emissivities at higher altitudes.  The
summit of the volcano, which is about 2 kilometers (1.2 miles) in height,
displays the lowest emissivity, while the emissivity becomes progressively
greater toward lower elevations.  The presence of minerals such as
pyrrohtite or pyrite may explain the low emissivities in some cases because
of their electrical properties and their stability at the temperatures and
pressures found at high altitudes on Venus.  The image was produced at the
JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           Magellan
                                        P-40991  MGN-108
                                        September 21, 1992

This Magellan image, centered at 41.3 degrees south latitude, 328.3 degrees
east longitude on Venus, was obtained in early September 1992, near the end
of the third mapping cycle.  Dimensions of the area imaged are
approximately 44 kilometers by 36 kilometers (27 miles by 22 miles).  The
radar-bright lineaments appear to be scarps associated with surface
faulting and extension.  The area pictured lies approximately 200
kilometers (124 miles) southeast of the volcano Hathor Mons, which rises
about 2 kilometers (1.2 miles) above the surrounding plain.  Hathor and two
other large volcanoes, Ushas and Innini, were imaged by Magellan for the
first time this September.  This region was the largest single remaining
gap in the Magellan global radar image map.  The area of Venus covered by
Magellan is now approximately 99% of the planet's surface or 455 million
square kilometers (172 million square miles).  That is approximately three
times the land area of all of the Earth's continents combined.
                          MAGELLAN PROJECT OFFICE

                                  P-41005
                                 10/20/92

This poster explains how Magellan radar data is processed into images.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           Magellan
                                        P-41056  MGN-109
                                        October 16, 1992

Crater Isabella, with a diameter of 175 kilometers (108 miles), seen in
this Magellan radar image, is the second largest impact crater on Venus.
The feature is named in honor of the 15th century queen of Spain, Isabella
of Castile.  Located at 30 degrees south latitude, 204 degrees east
longitude, the crater has two extensive flow-like structures extending to
the south and to the southeast.  The end of the southern flow partially
surrounds a pre-existing 40 kilometer (25 mile) circular volcanic shield.
The southeastern flow shows a complex pattern of channels and flow lobes,
and is overlain at its southeastern tip by deposits from a later 20
kilometer (12 mile) diameter impact crater, Cohn (for Carola Cohn,
Australian artist, 1892-1964).  The extensive flows, unique to Venusian
impact craters, are a continuing subject of study for a number of planetary
scientists.  It is thought that the flows may consist of "impact melt,"
rock melted by the intense heat released in the impact explosion.  An
alternate hypothesis invokes "debris flows," which may consist of clouds of
hot gases and both melted and solid rock fragments that race across the
landscape during the impact event.  That type of emplacement process is
similar to that which occurs in violent volcanic eruptions on Earth, such
as the 1991 Mount Pinatubo eruption in the Philippines.
                          MAGELLAN PROJECT OFFICE

                                  P-41147
                                 10/20/92

This global view of the surface of Venus is centered at 180 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the first cycle
of Magellan mapping are mapped onto a computer-simulated globe to create
this image.  Data gaps are filled with Pioneer-Venus Orbiter data, or a
constant mid-range value.  The image was produced at the JPL Multimission
Image Processing Laboratory and is a single frame from a video released at
the October 29, 1991, JPL news conference.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-41293
                                  1/15/93

This Magellan image of volcanic features and an impact crater with a dark
streak is located on the northern flank of Western Eistla Regio, centered
near 26 degrees north latitude, 354 degrees east longitude, and covers an
area 530 kilometers (329 miles) by 220 kilometers (136 miles).  Radar-
bright lava flows originating from the volcanoes Sif Mons and Gula Mons are
located at the left and right hand sides of the image respectively.  The
500 kilometer (310 mile) radar-dark streak cuts across a volcanic feature
and terminates at a 10 kilometer (6 mile) diameter impact crater at the
right side of the image.  The streak is an area where the surface is smooth
and is thought to have formed by shock waves transmitted through the
atmosphere during the impact process.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41294
                                  1/15/93

This image of the central part of Beta Regio is centered at 28 degrees
north latitude, 283 degrees east longitude and covers a region 1170
kilometers (725 miles) by 630 kilometers (391 miles).  Lying along a north-
south trend is the 1050 kilometers (651 miles) long rift valley Devana
Chasma.  The rift is similar to areas on the earth such as the east African
Rift where the crust is being stretched and faulted.  Located at the bottom
left of the image is the 5 kilometer (3 mile) high volcano Theia Mons.
Lava flows from this volcano contribute to infilling of the rift.  Faulting
along the western edge of Devana cut the volcano and its deposits
indicating that the emplacement of lava and faulting have been ongoing
processes.  The rift is widest, 240 kilometers (149 miles), in the vicinity
of Theia Mons and narrows to a width of 80 kilometers (50 miles) where it
intersects a region of tessera to the north.  Rhea Mons, located on the
western side of the rift, is located near the top center of the image and
is distinguished by a radar-dark oval area at its summit.  The 37
kilometers (23 miles) diameter impact crater Somerville is located to the
south of Rhea within Devana Chasma.  The rim of this crater has been
faulted due to extension and separated by a distance of approximately 10
kilometers (6 miles).

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41295
                                  1/15/93

This image, centered at 10 degrees south latitude, 78 degrees east
longitude covers a region 2500 kilometers (1550 miles) by 500 kilometers
(310 miles) along the southern flank of Aphrodite Terra.  The highland of
Aphrodite is a large area of complex ridged terrain also known as tessera.
Its complex structure shows evidence of both compressional and extensional
deformation.  Located along the southern edge of this upland is a zone of
fracturing and faulting 1000 kilometers (620 miles) long and 100 kilometers
(62 miles) wide that corresponds to Ix Chel Chasma.  A radar-dark oval
depression 150 kilometers (93 miles) long and 80 kilometers (50 miles) wide
corresponds to a large volcanic caldera located at the right hand part of
the image.  A radar-bright area to the north and west of the caldera
corresponds to a site where material on the surface is electrically
conductive and is thought to represent the presence of metallic minerals in
the rock.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41429
                                 12/21/92

The set of Magellan radar images shown here demonstrates the use of stereo
data to produce high resolution topography information.  The first two
images of the 24 kilometers (15 miles) diameter impact crater Riley,
located at 14.05 degrees north latitude, 72.3 degrees east longitude, are
from Magellan's first and third mapping cycles, respectively.  The look
angles for the two cycles are slightly different, allowing the images to be
viewed in stereo.  The third image is an orthorectified (radar distortions
removed) view of the crater that is combined with topography data taken
from a digital elevation model (DEM).  The DEM is created using an
algorithm that determines elevations from the displacement of identical
features in both images.  The abrupt boundary in elevations along the left
part of the crater is due to missing Cycle 3 data.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41461
                                 12/22/92

This Magellan image mosaic shows the largest (280 kilometers in diameter
[174 miles]) impact crater known to exist on Venus.  The crater is located
to the north of Aphrodite Terra and to the east of Eistla Regio at latitude
12.5 degrees north latitude and 57.2 degrees east longitude.  The
International Astronomical Union-Commission on Planetary Nomenclature has
approved Mead, after Margaret Mead--the American Anthropologist (1901-
1978), as the official name for this crater.

Mead is a multi-ring crater with its innermost, concentric scarp
interpreted to be the rim of the original crater cavity.  No inner peak-
ring of mountain massifs is observed on Mead.  The presence of hummocky,
radar-bright ejecta that crosses the radar-dark floor terrace and adjacent
outer rim scarp suggests that the floor terrace is a giant rotated block
that is concentric to, but lies outside of, the original crater cavity.
The flat, somewhat brighter inner floor of Mead is interpreted to result
from considerable infilling of the original crater cavity by impact melt
and/or by volcanic lavas.  To the southeast of the crater rim, emplacement
of hummocky ejecta appears to have been impeded by preexisting ridges, thus
suggesting a very low ground-hugging mode of deposition for this material.
Radar illumination on this Magellan image is from the left to the right.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
                          MAGELLAN PROJECT OFFICE

                                  P-41592
                                  5/26/93

This Magellan radar image of Ovda Regio is a compilation of data collected
during all three 8 month imaging cycles.  Areas where no images were
obtained are filled with topography data.  The scene is centered at 0
degrees north, 80 degrees east longitude and covers an area 6,300
kilometers by 6,300 kilometers (3,900 miles by 3,900 miles).  Ovda rises to
an elevation of over 3 kilometers (1.9 miles) above the surrounding
radar-dark (smooth) plains and is made up of a complexly deformed terrain
known as tesserae.  A band of east-west trending ridges located along the
north central part of Ovda, near the center of the image, are interpreted
to have formed by NW-SE oriented compression.  Along the southern edge of
the highland is a 200 kilometer (124 mile) wide zone of faulting and
fracturing formed by extension.  Near the northwest edge of Ovda (12.5
degrees north latitude, 57.2 degrees east longitude) is the 280 kilometer
(174 mile) diameter impact crater Mead.  A second, 31 kilometer (19 mile)
diameter crater named Adivar, has a radar-dark parabola shaped deposit and
is located to the northwest of the belt of ridges that form the northern
edge of the highland.  The radar-bright material at the eastern part of
Ovda (center left-hand part of the image) corresponds to the highest part
of this region.  The extreme brightness of this area is due both to a high
degree of roughness on the scale of the radar wavelength and the presence
of a metallic mineral in the surface rocks.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41843
                                  4/2/93

The Magellan spacecraft has completed three eight-month global radar
mapping cycles at Venus.  During most of the second and third cycles,
Magellan's radar was pointed at an angle to the surface that was slightly
different than the angle used during the first cycle.  Among the benefits
of these new perspectives of the surface is the opportunity to measure the
heights, depths and shapes of features with remarkable accuracy.  In this
example, a steep-sided, partially collapsed volcanic dome is viewed from
opposite sides - from the left in Cycle 1 (left) and from the right in
Cycle 2 (right).  The dome, approximately 40 kilometers (25 miles) in
diameter, lies at 16 degrees south latitude, 211.5 degrees east longitude,
southeast of Atla Regio.  The Cycle 1 image used an incidence angle of 40
degrees from vertical, which leads to a distortion of the image known as
foreshortening.  The top of the dome appears "pulled over" to the left, so
that the apparent distance between the upper scarp and the westernmost pit
at the base of the dome is 118 picture elements, or pixels.  At 75 meters
(246 feet) per pixel, this apparent distance is 8.85 kilometers (5.5
miles).  In the Cycle 2 image, with an incidence angle of 25 degrees, the
foreshortening is more pronounced and in the opposite direction to that in
the Cycle 1 image.  The apparent distance between the scarp and the pit is
243 pixels or 18.22 kilometers (11.3 miles).  There is a simple
mathematical equation that relates these apparent distortions, the
incidence angles and the height of the feature.  Solving this equation, the
height of the dome is found to be 2.6 kilometers (1.6 miles), among the
tallest of this class of volcanoes.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           Magellan
                                        P-41844  MGN-110
                                        March 10, 1993

During the third global cycle of Magellan's radar mapping mission, images
were obtained at viewing angles that were slightly different than those
used in the first two cycles.  This strategy was designed to produce stereo
image pairs, which take advantage of distortions induced by the different
views to provide details of the surface topography.  This is a stereo image
pair of crater Geopert-Meyer, named for the 20th century Polish physicist
and Nobel laureate (60 degrees north latitude, 26.5 degrees east
longitude).  The crater, 35 kilometers (22 miles) in diameter, lies above
an escarpment at the edge of a ridge belt in southern Ishtar Terra.  West
of the crater the scarp has more than 1 kilometer (0.6 mile) of relief.
Perception of relief may be obtained with stereo glasses or a stereoscope.
Some individuals may be able to fuse the images without the aid of those
devices.  The radar illumination for both images is from the west, or left
side of the scene.  Incidence angles are: Cycle 1 (left) 28 degrees, Cycle
3 (right) 15 degrees from vertical.  Analysis of stereo image pairs allows
planetary scientists to resolve details of topographic relationships on
Venusian craters, volcanoes, mountain belts, and fault zones.  The spatial
resolution of this topographic information is approximately ten times
better than that obtained by Magellan's altimetry experiment.
                          MAGELLAN PROJECT OFFICE

                                  P-41850
                                  4/2/93

The Magellan spacecraft has completed three eight-month global radar
mapping cycles at Venus.  During most of the second and third cycles,
Magellan's radar was pointed at an angle to the surface that was slightly
different than the angle used during the first cycle.  Among the benefits
of these new perspectives of the surface is the opportunity to measure the
heights, depths and shapes of features with remarkable accuracy.  In this
example, a type of volcanic pit known as a caldera is viewed from the west
side at two different angles - 42 degrees from the vertical in Cycle 1
(left) and 23 degrees from the vertical in Cycle 3 (right).  The two images
may be fused to form a three dimensional image by using a device such as a
stereoscope that directs each image exclusively to each eye.  The caldera,
approximately 50 kilometers (31 miles) in diameter, lies at 9.5 degrees
south latitude, 69 degrees east longitude, in the Ovda region of the
Aphrodite highlands.  The Cycle 1 image used an incidence angle of 42.5
degrees from vertical, which leads to a distortion of the image known as
elongation.  The western wall of the caldera appears "stretched out", so
that the apparent distance between the fractures on the west rim and the
floor of the caldera is 376 picture elements, or pixels.  At 75 meters (246
feet) per pixel, this apparent distance is 28.2 kilometers (17.5 miles).
In the Cycle 3 image, with an incidence angle of 22.7 degrees, the
elongation is more pronounced than in the Cycle 1 image.  The apparent
distance between the fractures and the floor is 399 pixels or 29.9
kilometers (18.5 miles).  There is a simple mathematical equation that
relates these apparent distortions, the incidence angles and the depth of
the feature.  Solving this equation, the depth of the caldera is found to
be 1.3 kilometers (0.8 miles).

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           Magellan
                                        P-41937  MGN-111
                                        March 10, 1993

These maps of Venus show how well various regions of the surface radiate
heat compared to a perfect radiator.  They display in color a quantity
called emissivity, observed using a Magellan Synthetic Aperture Radar (SAR)
receiver during its 24 months of systematic mapping in Venus orbit.  Color
is used to code the emission efficiency (see color bar).  Red corresponds
to the highest, blue to the lowest values of emissivity.  The upper image
shows the portion of the planet between 69 degrees north and 69 degrees
south latitude in Mercator projection; beneath it are the two polar regions
covering latitudes above 44 degrees in stereographic projection.  The
horizontal resolution varies with latitude, being determined solely by the
"footprint" of Magellan's high-gain SAR antenna beam.  Near the equator the
surface resolution is about 20 kilometers (12.4 miles) but at high
latitudes it degrades to as much as 100 kilometers (62 miles).  Emissivity
of the surface is a measure of how well the surface radiates heat.  Higher
regions, such as the Maxwell Montes (at top left center) and Aphrodite
Terra (along the equator at right center), usually show lower values of
emissivity than are typical of lower-lying areas.  On a cooler planet, such
as Earth or Mars, water or ice might explain the puzzling observations but
at the surface temperature of Venus -- 470 degrees C (878 F) -- neither can
be present.  Some theories call for the presence of an electrically-
conducting mineral such as pyrite (the minerals have an electrical field
when illuminated by radar); others suggest a material as yet unidentified
that has an extremely low electrical loss.  The data shown here were
compiled and analyzed at the Center for Space Research, Massachusetts
Institute of Technology.
PUBLIC INFORMATION OFFICE
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration
Pasadena, California 91109.  TELEPHONE [phone]

PHOTO CAPTION                           Magellan
                                        P-41938  MGN-112
                                        March 10, 1993

This map of the topography of Venus was obtained by the Magellan radar
altimeter during its 24 months of systematic mapping.  Color is used to
code elevation (see color bar), and simulated shading to emphasize relief.
Red corresponds to the highest, blue to the lowest elevations.  The upper
image shows the portion of the planet between 69 degrees north and 69
degrees south latitude in Mercator projection; beneath it are the two polar
regions covering latitudes above 44 degrees in stereographic projection.
Height accuracy is better than 50 meters; horizontal ("footprint")
resolution of the surface depends on spacecraft altitude, with a resolution
of about 10 kilometers (6 miles) near the equator and as much as 25
kilometers (15.5 miles) at higher latitudes.  The Magellan altimeter
acquired topography data over 98 percent of the planet's surface.  Gray
areas show the coarser results from the Pioneer Venus (1978) and Venera
15/16 (1983) radar altimeters, and indicate where data were not obtained by
Magellan.  The elevated region in the north is Ishtar Terra, dominated by
Maxwell Montes (the planet's highest mountains) which rise 11 kilometers
(36,000 feet) above the planetary mean elevation.  Southwest of Ishtar are
the highlands of Beta Regio and Phoebe Regio, which are bisected by a major
north-south trending rift zone.  The scorpion-shaped feature extending
along the equator between 70 and 210 degrees longitude is Aphrodite Terra,
a continent-like highland that contains several spectacular volcanoes at
its eastern limit: Maat, Ozza and Sapas Montes.  The altimetric data shown
here were compiled and analyzed at the Center for Space Research,
Massachusetts Institute of Technology.
                          MAGELLAN PROJECT OFFICE

                                 P-41938AC
                                  4/2/93

This map of the topography of Venus was obtained by the Magellan radar
altimeter during its 24 months of systematic mapping.  Color is used to
code elevation (see color bar), and simulated shading to emphasize relief.
Red corresponds to the highest, blue to the lowest elevations.  The upper
image shows the portion of the planet between 69 degrees north and 69
degrees south latitude in Mercator projection; beneath it are the two polar
regions covering latitudes above 44 degrees in stereographic projection.
Height accuracy is better than 50 meters; horizontal ("footprint")
resolution of the surface depends on spacecraft altitude, with a resolution
of about 10 kilometers (6 miles) near the equator and as much as 25
kilometers (15.5 miles) at higher latitudes.  The Magellan altimeter
acquired topography data over 98 percent of the planet's surface.  Gray
areas show the coarser results from the Pioneer Venus (1978) and Venera
15/16 (1983) radar altimeters, and indicate where data were not obtained by
Magellan.  The elevated region in the north is Ishtar Terra, dominated by
Maxwell Montes (the planet's highest mountains) which rise 11 kilometers
(36,000 feet) above the planetary mean elevation.  Southwest of Ishtar are
the highlands of Beta Regio and Phoebe Regio, which are bisected by a major
north-south trending rift zone.  The scorpion-shaped feature extending
along the equator between 70 and 210 degrees longitude is Aphrodite Terra,
a continent-like highland that contains several spectacular volcanoes at
its eastern limit: Maat, Ozza and Sapas Montes.  The altimetric data shown
here were compiled and analyzed at the Center for Space Research,
Massachusetts Institute of Technology.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41939
                                  3/11/93

These images show the radar reflecting efficiency of the Venus surface when
viewed from directly overhead by the Magellan altimeter during its 24
months of systematic mapping.  The lightest shades locate areas having the
highest values of reflectivity (as high as 70 percent in places), while
darker shades indicate areas of low reflection efficiency.  The upper image
shows the portion of the planet between 69 degrees north and 69 degrees
south latitude in Mercator projection; beneath it are the two polar regions
covering latitudes above 44 degrees in stereographic projection.
Resolution of the surface varies with spacecraft altitude, form about 10
kilometers near the equator to as much as 25 kilometers at high latitudes.
Black areas indicate where no data were obtained by Magellan.

There is a tendency for elevated regions, e.g. the Maxwell Montes (bright
feature at top center) and Aphrodite Terra (along the equator at right), to
show higher values of reflectivity than are typical of lower-lying areas.
The highest values (greater than 30 percent) are puzzling to understand.
On a cooler planet such as Earth or Mars, water or ice might explain the
observations, but at the 470-degree-Celsius temperature of the Venus
surface, neither can be present.  Some theories require the presence of
electrically conducting minerals such as pyrite; others suggest a material,
as yet unidentified, that has extremely low electrical loss.  The data
shown here were compiled and analyzed at the Center for Space Research,
Massachusetts Institute of Technology.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-41959
                                  4/1/93

This poster explains how Magellan data is processed into gravity
measurements.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                          Pasadena, Calif.  91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42356AC  MGN-113
                                        May 26, 1993

Magellan's fourth eight-month cycle of Venus mapping, which began in
September 1992, was dedicated to collecting gravity data.  The
computer-generated perspective shown here compares gravity and topography
over a region 12,700 kilometers by 8,450 kilometers (7,860 miles by 5,240
miles) and extends from longitudes 180 degrees east to 300 degrees east and
latitudes 40 degrees north to 40 degrees south.  The highlands of Beta
Regio and Atla Regio, sites of rifting and large volcanoes, have
corresponding high topography and high gravity.  These areas are
interpreted to be sites where hot mantle material is upwelling, forming
"hot spots," similar to areas on Earth such as Hawaii.  The two gravity
highs at Atla correspond to the volcanoes Maat Mons, the higher of the two
peaks, and Ozza Mons respectively.  Gravity anomalies at Atla and Beta are
the largest on Venus and these may be the sites of relatively young
geologic features.  In contrast to Earth, it is also seen that there is a
near-perfect correlation between gravity and topography with anomalies,
both positive (light blue) and negative (dark blue), being correlated with
topographic highs and lows.  This correspondence is interpreted to indicate
that, relative to Earth, the formation of features on Venus is more
strongly linked to fluid motions in the mantle.  The Magellan mission is
managed by the Jet Propulsion Laboratory for NASA's Office of Space
Science.
                          MAGELLAN PROJECT OFFICE

                                 P-42356BC
                                  5/26/93

Magellan's fourth Cycle of Venus mapping, which began in September of 1992,
was dedicated to collecting gravity data.  The global gravity map shown
here is centered near 330 longitude.  Gravity highs are indicated by the
reds and yellows and lows by the dark blue.  A gravity high corresponding
to the highland of Beta Regio, an area of rifting and volcanism, is seen at
the left.  A second gravity high, centered on the volcanic upland of
Western Eistla Regio, is located near the center of the image.  Both areas
are interpreted to be sites of mantle upwelling forming "hot spots",
similar to areas on the Earth such as Hawaii.  In the high northern and
southern latitudes no a priori constraint, information based on theoretical
analysis, is used to determine the gravity field.  Since the resolution of
the gravity data decreases with increasing spacecraft altitude (Magellan
was at an altitude greater than 700 km (430 miles) in the high northern and
southern latitudes), the red "waffled" features are regions where the
gravity field is very poorly determined.  Gravity data obtained after
Magellan is placed in a circular orbit will be greatly improved in these
polar regions and will give a global view at a constant resolution.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42359
                                  5/26/93

Magellan's fourth Cycle of Venus mapping, which began in September of 1992,
was dedicated to collecting gravity data.  This simple schematic shows the
method by which Magellan gravity data are acquired.  Gravity anomalies are
expressed as changes in the planet's gravity field due to the presence of
irregularities, such as mountains, valleys, craters, and/or regions of
different density materials at or below the surfaced.  These irregularities
cause the orbiting spacecraft to speed up or slow down.  The small changes
in speed (less than one millimeter/sec2) or accelerations are gravity data.
Earth-based radio signals transmitted to the spacecraft and returned to the
Earth can resolve speed measurements to 0.1 mm/sec.  The frequency shift in
the received radio signals (Doppler effect) make up the raw gravity
observation.  The signal is sampled every two seconds and over two million
data points have been acquired from the Magellan spacecraft.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42383  MGN-114
                                        May 26, 1993

This global view of the surface of Venus is centered at 90 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the three
eight-month cycles of Magellan radar mapping are mapped onto a
computer-simulated globe to create this image.  Magellan obtained coverage
of 98 percent of the surface of Venus.  Remaining gaps are filled with data
from previous Venus missions -- the Venera 15 and 16 radar and
Pioneer-Venus Orbiter altimetry -- and data from Earth-based radar
observations from the Arecibo radio telescope.  Simulated color is used to
enhance small-scale structures.  The simulated hues are based on color
images obtained by the Venera 13 and 14 landing craft.  The bright feature
near the center of the image is Ovda Regio, a mountainous region in the
western portion of the great Aphrodite equatorial highland.  The dark areas
scattered across the Venusian plains consist of extremely smooth deposits
associated with large meteorite impacts.  The image was produced by the
Solar System Visualization Project and the Magellan Science team at the Jet
Propulsion Laboratory Multimission Image Processing Laboratory.  The
Magellan mission is managed by JPL for NASA's Office of Space Science.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42384  MGN-115
                                        May 26, 1993

The northern hemisphere is displayed in this global view of the surface of
Venus.  The north pole is at the center of the image, with 0 degrees, 90
degrees, 180 degrees, 270 degrees east longitudes at the 6, 3, 12, and 9
o'clock positions, respectively, of an imaginary clock face.  Magellan
synthetic aperture radar mosaics from the three eight-month cycles of
Magellan radar mapping are mapped onto a computer-simulated globe to create
this image.  Magellan obtained coverage of 98 percent of the surface of
Venus.  Remaining gaps are filled with data from previous missions, (the
Soviet Venera 15 and 16 radar and Pioneer-Venus Orbiter altimetry) and data
from Earth-based radar observations from the Arecibo radio telescope.
Simulated color is used to enhance small-scale structures.  The simulated
hues are based on color images recorded by the Venera 13 and 14 landing
craft.  Maxwell Montes, the planet's highest mountain at 11 kilometers (6.6
miles) above the average elevation, is the bright feature in the lower
center of the image.  Other terrain types visible in this image include
tessera, ridge belts, lava flows, impact craters and coronae.  The image
was produced by the Solar System Visualization Project and the Magellan
Science team at the Jet Propulsion Laboratory Multimission Image Processing
Laboratory.  The Magellan mission is managed by JPL for NASA's Office of
Space Science.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42385  MGN-116
                                        May 26, 1993

Magellan radar image and altimetry data are combined in this view of three
volcanoes in the southern hemisphere of Venus.  The colors represent
elevations at the surface, with red and magenta being the highest and blue
being the lowest.  The area shown is centered at 33 degrees south latitude,
326 degrees east longitude, and is 2,300 kilometers by 1,650 kilometers
(1,380 miles by 990 miles) in size.  The data were acquired in September
1992 during the third and final phase of Magellan's radar mapping cycles.
From north to south, the volcanoes are Ushas, Innini and Hathor Montes.
Ushas Mons rises slightly less than 2 kilometers (1.2 miles) above the
surrounding plains, and is marked by numerous bright lava flows and a set
of north-south trending fractures.  Innini, at 2.8 kilometers (1.7 miles),
and Hathor, at 2.6 kilometers (1.6 miles), are taller than Ushas but are
less distinct in the appearance of their volcanic deposits.  The chain of
three volcanoes is thought to result from a large zone of hot material
upwelling from the Venusian mantle, a phenomenon known on Earth as a "hot
spot." The image was produced by the Magellan Science Team at the Jet
Propulsion Laboratory Multimission Image Processing Laboratory.  The
Magellan mission is managed by JPL for NASA's Office of Space Science.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42386  MGN-117
                                        May 26, 1993

Ushas Mons, a 2-kilometer-high (1.25-mile) volcano in the southern
hemisphere of Venus is shown in this Magellan radar image.  The image is
centered at 25 degrees south latitude, 323 degrees east longitude, and
shows an area approximately 600 kilometers (360 miles) on a side.  The
volcano is marked by numerous bright lava flows and a set of north-south
trending fractures, many of which appear to have formed after the lavas
were erupted onto the surface.  In the central summit area, however,
younger flows remain unfractured.  An impact crater can be seen among the
fractures in the upper center of the image.  The association of faulting
and volcanism is common on this type of volcano on Venus, and is believed
to result from a large zone of hot material upwelling from the Venusian
mantle, a phenomenon known on Earth as a "hot spot." Simulated color is
used to enhance small-scale structures.  The simulated hues are based on
color images recorded by the Venera 13 and 14 landing craft.  The data were
acquired during the third eight-month cycle of Magellan's radar mapping,
which end in September 1992.  Several narrow gaps in the Magellan coverage
are filled with low-resolution radar data obtained by the Earth-based
Arecibo radio telescope.  The image was produced by the Solar System
Visualization Project and the Magellan Science Team at the Jet Propulsion
Laboratory Multimission Image Processing Laboratory.  The Magellan mission
is managed by JPL for NASA's Office of Space Science.
                          MAGELLAN PROJECT OFFICE

                                  P-42387
                                  5/26/93

Ushas Mons, a 2 kilometer high (1.6 mile) volcano in the southern
hemisphere of Venus is shown in this Magellan radar image.  The image is
centered at 25 degrees south latitude, 323 degrees east longitude, and
shows an area approximately 600 kilometers (360 miles) on a side.  The
volcano is marked by numerous bright lava flows and a set of north-south
trending fractures, many of which appear to have formed after the lavas
were laid down.  In the central summit area, however, younger flows remain
unfractured.  An impact crater can be seen among the fractures in the upper
center of the image.  The association of faulting and volcanism is common
on this type of volcano on Venus, and is believed to result from a large
zone of hot material upwelling from the Venusian mantle, a phenomenon known
on Earth as a "hot spot".  The data were acquired during the final phase of
Magellan's radar mapping cycles, in September, 1992.  Several narrow gaps
in the Magellan coverage are filled with low resolution radar data obtained
by the Earth-based Arecibo radio-telescope.  The image was produced by the
Magellan Science Team at the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42388
                                  5/26/93

This global view of the surface of Venus is centered at 180 degrees east
longitude.  Magellan synthetic aperture radar mosaics from the full two
years of Magellan radar mapping are mapped onto a computer-simulated globe
to create this image.  Magellan obtained coverage of 98% of the surface of
Venus.  Remaining gaps are filled with data from previous Venus missions:
the Venera 15/16 radar and Pioneer-Venus Orbiter altimetry.  Simulated
color is used to enhance small-scale structure.  The simulated hues are
based on color images recorded by the Venera 13/14 landing craft.  The
twisting bright features that cross the globe from the lower left toward
the upper right are the highly fractured mountains and canyons of the
eastern Aphrodite highland.  Just to the right of center is the Atla
region, dominated by three large volcanoes: Sapas, Maat and Ozza Montes.
The image was produced by the Solar System visualization project and the
Magellan Science team at the JPL Multimission Image Processing Laboratory.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42392  MGN-118
                                        May 26, 1993

This computer-generated perspective view of the highland of Ovda Regio on
Venus shows Magellan radar data superimposed on topography.  This scene is
made up of a compilation of radar images collected during all three of
Magellan's eight-month mapping cycles.  Simulated color, based on color
images obtained by the Venera 14 and 15 landers, is used to enhance
small-scale structure.  The view is from the northeast looking to the
southwest and vertical exaggeration is 22.5 times.  Exaggeration of relief
is a common tool scientists use to enhance relationships between structure
(for example, faults and fractures) and topography.  Ovda Regio covers an
area 6,300 kilometers by 2,100 kilometers (3,900 miles by 1,300 miles),
rises over 3 kilometers (1.9 miles) above the surrounding plains, and is
made up of complex ridge terrain, also know as tessera.  At the bottom
right of this scene, along the northern edge of the highland, are a series
east-west trending ridges that are interpreted to have formed by
northwest-southeast-oriented compression.  In several places the ridges are
flooded by radar-dark (smooth) lava flows, indicating that volcanic
activity postdates the formation of the ridges.  The terrain in the
interior of Ovda forms a chaotic pattern indicating multiple directions of
deformation.  The Magellan mission is managed by the Jet Propulsion
Laboratory for NASA's Office of Space Science.
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE [phone]

PHOTO CAPTION                           MAGELLAN
                                        P-42393  MGN-119
                                        May 26, 1993

This computer-generated perspective view of the highland of Ovda Regio on
Venus shows Magellan radar data superimposed on topography.  This scene is
made up of a compilation of radar images collected during all three of
Magellan's eight-month mapping cycles.  Simulated color, based on color
images obtained by the Venera 14 and 15 landers, is used to enhance
small-scale structure.  The view is from west to east and vertical
exaggeration is 22.5 times.  Exaggeration of relief is a common tool
scientists use to enhance relationships between structure (for example,
faults and fractures) and topography.  Ovda Regio covers an area 6,300
kilometers by 2,100 kilometers (3,900 miles by 1,300 miles), rises over 3
kilometers (1.9 miles) above the surrounding plains, and is made up of
complex ridge terrain, also know as tessera.  Located in the foreground is
a 400 kilometer by 250 kilometer (250 mile by 155 mile) oval depression
that contains abundant faults and fractures.  This feature is surrounded by
radar-dark lava flows and is a site of volcanism and extension.  The dark
volcanic plains flood surrounding complex ridge terrain indicating that
lava emplacement postdates the tesserae.  The enhanced radar brightness of
the complex ridge terrain in the background is due to both roughness on the
scale of the radar wavelength and the presence of a metallic mineral in the
surface.  The Magellan mission is managed by the Jet Propulsion Laboratory
for NASA's Office of Space Science.
                          MAGELLAN PROJECT OFFICE

                                  P-42611
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

In this image, centered at 11.6 degrees south latitude, 89.7 degrees east
longitude, channels that once drained molten lava from the site of an
eruption extend like tentacles from a large collapse pit.  The pit is as
deep as 1 kilometer in places.  The highlands of Aphrodite Terra, though
dominated by tectonically disrupted terrains, also include fresher-
appearing volcanic terrains such as this one.  The image is 73 kilometers
wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42612
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

In this image, centered at 58.5 degrees north latitude, 26.5 degrees east
longitude, the crater Geopert-Meyer (named for the Polish Nobel laureate
physicist), is precariously perched at the edge of a deformed mountain belt
in Ishtar Terra.  The crater rim appears to have been disrupted by later
faulting, and its northwest portion has collapsed into the 1 kilometer-deep
trough below.  The image is 154 kilometers wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42613
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

In this image, centered at 9.5 degrees south latitude, 69 east longitude, a
1.3 kilometer-deep volcanic caldera lies in a fractured terrain in the Ovda
region of Aphrodite Terra.  Such features are believed to form by the
collapse of the surface following the withdrawal of magma from an
underground storage chamber.  The smooth, radar-dark floor suggests that
lava may have ponded there at a late stage of the caldera's evolution.  The
image is 60 kilometers wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42614
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

In this image, centered at 7 degrees south latitude, 69.6 degrees east
longitude, isolated hills and ridges are all that remain from a region of
tessera in western Aphrodite that has subsided and been flooded by later
volcanic flows.  Remnants of tessera are found in virtually all regions of
Venus, and may represent an earlier era of widespread tectonic deformation.
The image is 77 kilometers wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42615
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

In this image, centered at 41.8 degrees north latitude, 89.6 east
longitude, at the eastern edge of the Tellus upland, large quasi-circular
areas of tessera appear to have collapsed and been flooded by volcanic
materials.  Numerous small volcanic domes (1 to 5 kilometer diameter) have
formed on the smooth plain developed in the low-lying areas.  The image is
154 kilometers wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42616
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

This image shows Warren crater located at 11.8 degrees south latitude,
176.5 degrees east longitude.  The image is 90 kilometers in width.  Warren
crater, named for the American colonial woman of letters Mercy Warren, is
among the larger impact craters of Venus, with a diameter of 50 kilometers.
Much of the floor of the crater consists of a relatively smooth, yet radar-
bright material of unknown composition.  Most of the tectonic deformation
of this area, which is associated with the Dali Chasma trough system to the
south, appears to pre-date the impact event.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42617
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

A zone of fracturing and extension emanates from the southwest margin of
Latona Corona.  The valleys developed in this rift zone clearly indicate
that the crust has been pulled apart in an east-west direction, opening
gashes and down-dropping intervening blocks known as graben.  The image is
centered at 25.7 degrees south latitude, 166 degrees east longitude, and is
98 kilometers wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42618
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

The Diana Chasma-Dali Chasma trough system dominates the topography of
east-central Aphrodite Terra.  Shown here is a portion of Diana Chasma that
displays total relief of about 6 kilometers.  Controversy exists concerning
the origin of these great valleys.  One theory involves a process similar
to that found at the Earth's subduction zones.  The image is centered at 14
degrees south latitude, 155.5 degrees east longitude and is 151 kilometers
wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42619
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).

By directing each image exclusively to each eye with a stereoscopic viewer,
the images can be fused to create a three-dimensional scene.  When viewed
with a standard stereoscope, the perceived height differences are
exaggerated 5 to 10 times relative to the horizontal scale of the images.

One of Magellan's most intriguing discoveries was the class of volcanoes
known as steep-sided domes or "pancakes." Centered at 25.9 degrees south
latitude, 80 degrees east longitude, this dome sits near the rim of a
corona-like structure in Aino Planitia.  At 40 kilometers in diameter and
near 2 kilometers in height, this dome is much larger than the terrestrial
rhyolite domes that provide Earth's best analog.  The image is 90
kilometers wide.  Geologists are continuing to analyze data on the steep-
sided domes to determine the composition and dynamics of their lavas.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109
                          MAGELLAN PROJECT OFFICE

                                  P-42620
                                  7/14/93

Magellan's third global cycle of radar mapping was devoted primarily to
obtaining repeat coverage of regions seen in previous cycles, using a
different viewing angle.  The resulting "stereo" pairs provide details of
the surface topography at a resolution comparable to the image resolution
(about 120 meters or 400 feet).  By directing each image exclusively to
each eye with a stereoscopic viewer, the images can be fused to create a
three-dimensional scene.  When viewed with a standard stereoscope, the
perceived height differences are exaggerated 5 to 10 times relative to the
horizontal scale of the images.

In this image, Latona Corona, centered at 20.6 degrees south latitude,
172.5 degrees east longitude, is bounded on its north rim by Dali Chasma.
The southern half of the corona consists of a series of roughly concentric
scarp-and-trough features, the innermost of which is shown here.  Near the
left edge of the image, the trough is over 4 kilometers deep.  The image is
135 kilometers wide.

Three-dimensional views of Venus allow geologists to reconstruct the
details of geologic events.  The high resolution of these stereo image
pairs allows the construction of digital topographic maps (digital
elevation models or DEMs) from which precise measurements can be made of
the heights, depths, slopes and volumes of geologic structures.  Magellan
observed over 20 per cent of the surface in this dual-perspective mode, and
analysis of the third dimension of Venus is sure to continue for decades.

                         Jet Propulsion Laboratory
                    California Institute of Technology
               National Aeronautics and Space Administration
                        Pasadena, California 91109