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Shuttle Radar Topography Mission




The objective of the Shuttle RadarTopography Mission is to obtain elevation radar data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. The SRTM radar data have many applications.

The Shuttle Radar Topography Mission (SRTM) is an international project spearheaded by the National Geospatial-Intelligence Agency and NASA whose objective is to obtain the most complete high-resolution digital topographic database of the Earth.

Photo of SRTM hardware on Shuttle Endeavour
Part of the SRTM hardware is photographed through Endeavour's aft flight deck windows about halfway into the mission. The mast is deployed from the mast canister, and the main antenna can be seen behind the mast.

During the Shuttle Radar Topography Mission, a specially modified radar system flew onboard Space Shuttle Endeavour for 11 days in February of 2000. This radar system gathered data that will result in the most accurate and complete topographic map of Earth's surface that has ever been assembled.

The processed SRTM radar data can be tailored to meet the needs of the military, civil, and scientific user communities. But other uses of this data include improved water drainage modeling, more realistic flight simulators, navigation safety, better locations for cell phone towers, and even improved maps for backpackers.

Just about any project that requires accurate knowledge of the shape and height of the land can benefit from this data. Some examples are flood control, soil conservation, reforestation, volcano monitoring, earthquake research, and glacier movement monitoring.

SRTM used of a technique called radar interferometry . In radar interferometry, two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations the SRTM hardware consisted of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast that extended 60 meters (200 feet) from the shuttle.

SRTM was launched into an orbit with an inclination of 57 degrees. This allowed SRTM's radars to cover most of Earth's land surface that lies between 60 degrees north and 56 degrees south latitude.  This is about 80 percent of Earth's land mass.

Artist representation of SRTM in space
Artist representation of SRTM in space. Main antenna is located in the payload bay, the mast is deployed to 60 meters (200 feet), and the outboard antenna is attached to the end of the mast.
(Courtesy of the German Aerospace Center)