The Shuttle Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) (Figure 1) is a cooperative space shuttle experiment between NASA, the German Space Agency, and the Italian Space Agency. The experiment is the next evolutionary step in NASA's Spaceborne Imaging Radar (SIR) program that began with the Seasat Synthetic Aperture Radar (SAR) in 1978 and continued with SIR-A in 1981 and SIR-B in 1984. It also represents a continuation of Germany's imaging radar program, which started with the Microwave Remote Sensing Experiment flown aboard the Shuttle on the first SPACELAB mission in 1983. The SIR-C/X-SAR mission benefits from synergism with the Magellan mission to Venus, other international spaceborne radar programs, and prototype aircraft sensors such as the Jet Propulsion Laboratory's Airborne SAR (AIRSAR) and the German Aerospace Establishment (DLR) E-SAR.