The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000. SRTM collected an unprecedented 8.6 Terabytes of interferometric C-band Synthetic Aperture Radar (SAR) data (equivalent to about 14,317 CDs). This data will be processed to produce a rectified terrain-corrected mosaic of approximately 80% of the Earth's land surface topography (between 60 degrees North and 56 degrees South latitude) at 30-meter resolution. This would be 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.
To acquire topographic (elevation) data, the SRTM payload was outfitted with two radar antennas, and a technique called radar interferometry was used. 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. One antenna was located in the shuttle's payload bay, the other on the end of a 60-meter (200-foot) mast that extended from the payload pay once the Shuttle was in space. Virtually all of the land surface between +/- 60 degrees latitude was mapped by SRTM. Processing of the C-band data took two years. During this time, JPL generated and released "showpiece" derived products.
SRTM is an international project spearheaded by the National Geospatial-Intelligence Agency (NGA), NASA, NIMA, and the German and Italian space agencies.