P-49846 May 14, 1998
This spaceborne radar image covers a rugged mountainous area of
southeast Tibet, about 90 kilometers (56 miles) east of the city
of Lhasa. In the lower right corner is a wide valley of the Lhasa
River, which is populated with Tibetan farmers and yak herders,
and includes the village of Menba. Mountains in this area reach
about 5800 meters (19,000) feet above sea level, while the valley
floors lie about 4300 meters (14,000 feet) above sea level. The
Lhasa River is part of the Brahmaputra River system, one of the
larger rivers in southeast Asia eroding the Tibetan Plateau. The
rugged relief in this area reflects the recent erosion of this
part of the Plateau. Most of the rocks exposed outside of the
river valleys are granites, which have a brown-orange color on
the image. In the upper left center of the image and in a few
other patches, there are some older sedimentary and volcanic
rocks that appear more bluish in the radar image. Geologists are
using radar images like this one to map the distribution of
different rock types and try to understand the history of the
formation and erosion of the Tibetan Plateau. This image was
acquired by the Spaceborne Imaging Radar-C/X-band Synthetic
Aperture Radar (SIR-C/X-SAR) on April 10, 1994, on board the
space shuttle Endeavour. North is toward the upper left. The
image is 49.8 kilometers by 33.6 kilometers (30.9 miles by 20.8
miles) and is centered at 30.2 degrees north latitude, 92.3
degrees east longitude. The colors assigned to the radar
frequencies and polarizations are as follows: red is L- band,
horizontally transmitted, vertically received; green is C-band,
horizontally transmitted, vertically received; and blue is the
ratio of C-band to L-band, horizontally transmitted and
received. SIR-C/X-SAR, a joint mission of the German, Italian and
United States space agencies, is part of NASA’s Earth Science
Enterprise.
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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.
