The Shuttle Radar Topography Mission (SRTM) is an international research effort that obtained digital elevation models on a near-global scale from 56°S to 60°N, to generate the most complete high-resolution digital topographic database of Earth prior to the release of the ASTER GDEM in 2009. The technique employed for generating topographic data by radar is known as interferometric synthetic aperture radar. It flew onboard the 11-day STS-99 mission in February 2000.
Intermap Technologies was the prime contractor for processing the interferometric synthetic aperture radar data. The elevation models derived from the SRTM data are used in geographic information systems. They can be downloaded freely over the Internet, and their file format (.hgt) is widely supported.