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Shuttle Imaging Radar

Overview:

JPL's Seasat satellite in 1978 established that images could be taken of Earth from orbit using radar pulses rather than optical light as the illumination. Imaging radar has various advantages over images that use visible light; it can "see" through desert sands, for example, to detect the remnants of ancient riverbeds. A series of imaging radar missions were therefore flown on NASA's Space Shuttle over the next 20 years.

The first mission, called Shuttle Imaging Radar-A, was carried into space on STS-2, only the second mission flown by the then-new shuttle. This mission launched from Kennedy Space Center, Florida, on November 12, 1981, and landed two days later.

Three years later, a follow-up mission called Shuttle Imaging Radar-B was flown on shuttle mission STS-41G, which launched October 5, 1984, and landed seven days later.

After that project, a decade went by before imaging radar flew on the shuttle again. For the next mission, JPL's Spaceborne Imaging Radar-C was combined with a German-Italian in student called X-Band Synthetic Aperture Radar which used a higher-frequency radar than the American instrument. This package flew twice on the space shuttle, once on STS-59 from April 9 to 20, 1994, and the second time on STS-68 from September 30 to October 11, 1994.

The instrument's mammoth radar antenna was then augmented with a second antenna that would allow it to map the height of features on Earth using a technique somewhat similar to stereo photography. Sponsored by the Defense Department's National Image Mapping Agency, this package flew under the name Shuttle Radar Topography Mission on STS-99 from February 11 to 22, 2000.

The Shuttle Imaging Radar instruments were designed and built by JPL, where the antennas were the largest space structures ever built at the Laboratory.