PC Media 4/PC MEDIA CD04.iso/nasa/sc-death.txt

Text File | 1995-02-23 | 4KB | 71 lines

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF.  91109.  TELEPHONE [phone]

PHOTO CAPTION                                             P-43883
                                                   April 11, 1994

This image shows Death Valley, California, centered at 36.629
degrees north latitude, 117.069 degrees west longitude.  The
image shows Furnace Creek alluvial fan and Furnace Creek Ranch at
the far right, and the sand dunes near Stove Pipe Wells at the
center.  The dark fork-shaped feature between Furnace Creek fan
and the dunes is a smooth flood-plain which encloses Cottonball
Basin.  This SIR-C/X-SAR supersite is an area of extensive field
investigations and has been visited by both Space Radar Lab
astronaut crews.  Elevations in the valley range from 70 meters
(230 feet) below sea level, the lowest in the United States, to
more than 3,300 meters (10,800 feet) above sea level.  Scientists
are using SIR-C/X-SAR data from Death Valley to help answer a
number of different questions about Earth's geology.  One
question concerns how alluvial fans are formed and change through
time under the influence of climatic changes and earthquakes.
Alluvial fans are gravel deposits that wash down from the
mountains over time.  They are visible in the image as circular,
fan-shaped bright areas extending into the darker valley floor
from the mountains.  Information about the alluvial fans helps
scientists study Earth's ancient climate.  Scientists know the
fans are built up through climatic and tectonic processes and
they will use the SIR-C/X-SAR data to understand the nature and
rates of weathering processes on the fans, soil formation and the
transport of sand and dust by the wind.  SIR-C/X-SAR's
sensitivity to centimeter-scale (inch-scale) roughness provides
detailed maps of surface texture.  Such information can be used
to study the occurrence and movement of dust storms and sand
dunes.  The goal of these studies is to gain a better
understanding of the record of past climatic changes and the
effects of those changes on a sensitive environment.  This may
lead to a better ability to predict future response of the land
to different potential global climate-change scenarios.

Death Valley is also one of the primary calibration sites for
SIR-C/X-SAR.  The bright dots near the center of the image are
corner reflectors that have been set-up to calibrate the radar as
the shuttle passes overhead.  Thirty triangular-shaped reflectors
(they look like aluminum pyramids) have been deployed by the
calibration team from JPL over a 40- by 40-kilometer (25- by 25-
mile) area in and around Death Valley.   The calibration team
will also deploy transponders (electronic reflectors) and
receivers to measure the radar signals from SIR- C/X-SAR on the
ground.

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).

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