Launch: November 12, 1981; October 5, 1984; April 9, 1994; September 30, 1994; February 11, 2000
Purpose: Earth imaging using radar pulses
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
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.
For more information, see the Shuttle
Radar Topography Mission home page or the
Spaceborne Imaging Radar/X-band Synthetic Aperture Radar home page.