Space Radar Spies Great Wall

^{Image Credit: NASA}

The Apollo astronauts never did see the Great Wall of China from the moon, as had been reported. But it is easily visible with space radar.

The two spaceborne radar images above show part of the Great Wall of China as it passes through a desert region in north-central China, about 400 miles west of Beijing. Two walls can be seen right next to each other in the enlarged section. The wall to the left is newer, built around 600 years ago during the Ming Dynasty. This wall is 16-26 feet high in this area. The wall to the right is more ragged looking. It was built 1500 years ago during the Sui Dynasty. Parts of it are covered by dirt and blowing sand.

Features such as the Great Wall are easily seen with spaceborne imaging radar because the wall's steep, smooth sides strongly reflect the radar beam. The above images were taken by the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 10, 1994. SIR-C/X-SAR is a joint mission of the German, Italian, and United States space agencies, and part of NASA's Mission to Planet Earth.

More Cool Stuff

The above observation was featured in NASA's Mission to Planet Earth "What's News," April 8, 1996:

http://www.hq.nasa.gov/office/mtpe/whatsnews.html

ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1996/96-77.txt

For additional information about radar imagery of the Great Wall of China, go to NASA's Jet Propulsion Laboratory (JPL):

http://southport.jpl.nasa.gov/imagemaps/html/srl-greatwall.html

Check out the JPL Imaging Radar homepage for information about SIR-C/X-SAR, radar views of the earth, exciting 3-D radar flights, science and applications, and more:

http://southport.jpl.nasa.gov

Learn more about how radar imaging can reveal hidden desert features in our electronic exhibit, "The Search for Ubar":

http://observe.ivv.nasa.gov/nasa/exhibits/ubar/ubar_0.html

Check out other observations in the Observation of the Week Archive.