The Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is the most advanced civilian spaceborne radar yet flown. It is the world's first spaceborne multifrequency, multipolarization system and incorporates a number of advanced capabilities and innovative features and modes, including SCANSAR and interferometry. SIR-C/X-SAR was successfully flown twice in 1994 aboard the Shuttle Endeavour as part of an international imaging radar mission. The United States' SIR-C operates at L- and C-bands, each with multiple polarization, utilizing an active phased array antenna. The German/Italian X-SAR operates synchronously with SIR-C at X-band with a single polarization to collect data over common sites. Over the two flights, a total of 143 hours (93 terabits) of SAR data were digitally recorded on tape for subsequent processing in the U.S., Germany, and Italy. This advanced, multifaceted system has produced a rich data set for Earth science and remote sensing utility development and has the potential for additional flights.