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 bgcolor=ffffff 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. P-45156

Angkor, Cambodia

February 7, 1995

Images from the international Space Radar Laboratory may help researchers find previously unknown settlements near the ancient city of Angkor in Cambodia.

The radar data were obtained during the October 1994 flight of the space shuttle Endeavour, processed and then sent in January to the World Monuments Fund in New York City. The group had approached the radar science team about observing the Angkor area after the Space Radar Laboratory's first flight in April 1994.

"I had read about the radar mission while the April mission was in progress and instantly surmised that it would have applications to the international research efforts at Angkor," said John Stubbs, program director of the World Monuments Fund. "I didn't really know where to start, but I was hopeful NASA would be willing to image the area around Angkor."

Angkor is a vast complex of more than 60 temples dating back to the 9th century that served as the spiritual center for the Khmer people. In its heyday the city housed a population of about 1 million people and was supported by a massive hydrological system of reservoirs and canals.

The April 1994 flight of the Space Radar Laboratory's complementary radars -- the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) -- first demonstrated their capability to obtain vast amounts of data that could be used to advance many disciplines, including ecological, oceanographic, geologic and agricultural investigations.

"We realized after the huge success of the first flight that we could be more flexible in adding new sites to the timeline of flight two," said Dr. Diane Evans, the SIR-C project scientist at NASA's Jet Propulsion Laboratory. "Since our science team was interested in studying as much of the tropical rainforest as possible, Cambodia and the Angkor site complemented our ecology objectives."

Today Angkor is hidden beneath a dense rainforest canopy. Its temples have been ravaged by weather, war and looters. Remnants of an extensive irrigation system, which fell into disuse long ago, have intrigued archeologists studying the ruins.

"The radar's ability to penetrate clouds and vegetation makes it an ideal tool for studying Angkor," Stubbs explained. "I can see the hydrological system very clearly in the radar imagery and preliminary analysis reveals what may be evidence of organized settlement of large tracts of land to the north of the present archeological park, which until now, has gone unnoticed."

The SIR-C/X-SAR data will be used by the World Monuments Fund, the Royal Angkor Foundation and research teams from more than 11 countries to understand how the city grew, flourished and eventually was abandoned over an 800-year period.

"The 'temple mountain' monuments at Angkor, such as Angkor Wat and the Bayon, are not unlike some of the pyramid-like forms encountered in Central America," Stubbs said. "The sheer size and sophistication of Angkor's great city plan, now enveloped in dense jungle, set this ancient capital apart as the ultimate jungle ruin."

SIR-C/X-SAR is a joint mission of the United States, German and Italian space agencies. The Jet Propulsion Laboratory built and manages the Spaceborne Imaging Radar-C portion of the mission for NASA's Office of Mission to Planet Earth.


For a full-resolution (32-megabyte) version of the image above, press here

This image is a part of the Image Library sponsored by the Texas Space Grant Consortium and the Center for Space Research - University of Texas at Austin. It was taken from


Last Modified: 07/10/00