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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, CALIF. 91109. TELEPHONE (818) 354-5011
PHOTO CAPTION P-45156
February 7, 1995
Angkor, Cambodia
L, C bands
This is an image of the area around the city of Angkor,
Cambodia. The city houses an ancient complex of more than
60 temples dating back to the 9th century. The principal
complex, Angkor Wat, is the bright square just left of the
center of the image. It is surrounded by a reservoir that
appears in this image as a thick black line. The larger
bright square above Angkor Wat is another temple complex
called Angkor Thom. Archeologists studying this image
believe the blue-purple area slightly north of Angkor Thom
may be previously undiscovered structures. In the lower
right is a bright rectangle surrounded by a dark reservoir,
which houses the temple complex Chau Srei Vibol. In its
heyday, Angkor had a population of 1 million residents and
was the spiritual center for the Khmer people until it was
abandoned in the 15th century. The image was acquired by
the Spaceborne Imaging Radar-C/X-band Synthetic Aperture
Radar (SIR-C/X-SAR) on the 15th orbit of the space shuttle
Endeavour on September 30, 1994. The image shows an area
approximately 55 kilometers by 85 kilometers (34 miles by 53
miles) that is centered at 13.43 degrees north latitude and
103.9 degrees east longitude. 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); blue represents the C-band
(horizontally transmitted and vertically received). The
body of water in the south-southwest corner is Tonle Sap,
Cambodia's great central lake. The urban area at the lower
left of the image is the present-day town of Siem Reap. The
adjoining lines are both modern and ancient roads and the
remains of Angkor's vast canal system that was used for both
irrigation and transportation. The large black rectangles
are ancient reservoirs. Today the Angkor complex is hidden
beneath a dense rainforest canopy, making it difficult for
researchers on the ground to study the ancient city. The
SIR-C/X-SAR data are being used by archaeologists at the
World Monuments Fund and the Royal Angkor Foundation to
understand how the city grew, flourished and later fell into
disuse over an 800-year period. The data are also being
used to help reconstruct the vast system of hydrological
works, canals and reservoirs, which have gone out of use
over time. Research teams from more than 11 countries will
be using this data to study the Angkor complex.
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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.
#####