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sc-isabe.txt
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1995-02-23
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PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.TELEPHONE (818) 354-5011
PHOTO CAPTION P-43913
April 15, 1994
Isabela 1, 3-D
This is a three-dimensional view of Isabela, one of the Galapagos
Islands located off the western coast of Ecuador, South America.
This view was constructed by overlaying a Spaceborne Imaging
Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) image on a
digital elevation map produced by TOPSAR, a prototype airborne
interferometric radar which produces simultaneous image and
elevation data. The vertical scale in this image is exaggerated
by a factor of 1.87. The SIR-C/X-SAR image was taken on the 40th
orbit of space shuttle Endeavour. The image is centered at about
0.5 degree south latitude and 91 degrees west longitude and
covers an area of 75 by 60 kilometers (47 by 37 miles). The
radar incidence angle at the center of the image is about 20
degrees. The western Galapagos Islands, which lie about 1,200
kilometers (750 miles) west of Ecuador in the eastern Pacific,
have six active volcanoes similar to the volcanoes found in
Hawaii and reflect the volcanic processes that occur where the
ocean floor is created. Since the time of Charles Darwin's visit
to the area in 1835, there have been more than 60 recorded
eruptions on these volcanoes. This SIR-C/X-SAR image of Alcedo
and Sierra Negra volcanoes shows the rougher lava flows as bright
features, while ash deposits and smooth pahoehoe lava flows
appear dark. Vertical exaggeration of relief is a common tool
scientists use to detect relationships between structure (for
example, faults, and fractures) and topography.
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Spaceborne Imaging Radar-C and X-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).
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