The radars used during the SRTM mission were actually developed and flown on two shuttle missions that took place in 1994. The Shuttle Imaging Radar-C (SIR-C) and the X-Band Synthetic Aperture Radar (X-SAR) flew on board the space shuttle in April and October of 1994 to gather data about Earth's environment.

SIR-C was developed by NASA. X-SAR was developed through a joint collaboration with the space agencies of Germany and Italy. So SRTM was actually a mission that re-used proven flight hardware plus some additional equipment that was needed to get the job done.

The major innovation of SRTM was that additional antennas were deployed on a 60-meter mast so the system could operate as a single-pass interferometer to efficiently and accurately collect elevation data. The 60-meter mast is the longest structure ever flown in space.

Funding for SRTM came from the Defense Department's National Geospatial-Intelligence Agency (NGA), while NASA supplied the SIR-C hardware, shuttle launch, ground systems, mission operations, and data processing support. The German Aerospace Center (DLR) and the Italian Space Agency (ASI) supplied the X-SAR hardware, ground systems, mission operations, and data processing support.