home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
PC Media 4
/
PC MEDIA CD04.iso
/
nasa
/
sc-roter.txt
< prev
next >
Wrap
Text File
|
1995-02-23
|
4KB
|
71 lines
SPACEBORNE IMAGING RADAR-C/
X-BAND SYNTHETIC APERTURE RADAR
(SIR-C/X-SAR)
PHOTO CAPTION P-45149
January 26, 1995
Roter Kamm, Namibia
This space radar image shows the Roter Kamm impact crater in
southwest Namibia. The crater rim is seen in the lower
center of the image as a radar-bright, circular feature.
Geologists believe the crater was formed by a meteorite that
collided with Earth approximately 5 million years ago. The
data were acquired by the Spaceborne Imaging Radar-C/X-Band
Synthetic Aperture Radar (SIR-C/X-SAR) instrument onboard
space shuttle Endeavour on April 14, 1994. The area is
located at 27.8 degrees south latitude and 16.2 degrees east
longitude in southern Africa. The colors in this image were
obtained using the following radar channels: red represents
the L-band (horizontally transmitted and received); green
represents the L-band (horizontally transmitted and
vertically received); and blue represents the C-band
(horizontally transmitted and vertically received). The
area shown is approximately 25.5 kilometers (15.8 miles) by
36.4 kilometers (22.5 miles), with north toward the lower
right. The bright white irregular feature in the lower left
corner is a small hill of exposed rock outcrop. Roter Kamm
is a moderate sized impact crater, 2.5 kilometers (1.5
miles) in diameter rim to rim, and is 130 meters (400 feet)
deep. However, its original floor is covered by sand
deposits at least 100 meters (300 feet) thick. In a
conventional aerial photograph, the brightly colored
surfaces immediately surrounding the crater cannot be seen
because they are covered by sand. The faint blue surfaces
adjacent to the rim may indicate the presence of a layer of
rocks ejected from the crater during the impact. The
darkest areas are thick windblown sand deposits which form
dunes and sand sheets. The sand surface is smooth relative
to the surrounding granite and limestone rock outcrops and
appears dark in radar image. The green tones are related
primarily to larger vegetation growing on sand soil, and the
reddish tones are associated with thinly mantled limestone
outcrops. Studies of impact craters on the surface of the
Earth help geologists understand the role of the impact
process in the Earth's evolution, including effects on the
atmosphere and on biological evolution.
-----
Spaceborne Imaging Radar-C and X-band Synthetic Aperture
Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet
Earth. The radars illuminate Earth with microwaves, allowing
detailed observations at any time, regardless of weather or
sunlight conditions. SIR-C/X-SAR uses three microwave
wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3
cm). The multi-frequency data will be used by the
international scientific community to better understand the
global environment and how it is changing. The SIR-C/X-SAR
data, complemented by aircraft and ground studies, will give
scientists clearer insights into those environmental changes
which are caused by nature and those changes which are
induced by human activity. SIR-C was developed by NASA's
Jet Propulsion Laboratory. X-SAR was developed by the
Dornier and Alenia Spazio companies for the German space
agency, Deutsche Agentur fuer Raumfahrtangelegenheiten
(DARA), and the Italian space agency, Agenzia Spaziale
Italiana (ASI), with the Deutsche Forschungsanstalt fuer
Luft und Raumfahrt e.V.(DLR), the major partner in science,
operations and data processing of X-SAR.
#####