The evolution of the Spaceborne Imaging Radar (SIR) has lead to a multipolarization, multifrequency synthetic aperture radar (SAR) with variable imaging geometry which will be ready for flight on the Earth Observing System (Eos). Nominally, this SAR will be a three frequency (L-, C- and X-bands) system with quadpolarization available for the L- and C-bands. It will be capable of acquiring multiincidence angle data using electronic beam steering and other imaging geometries by mechanically pitching, yawing and rolling the antenna. The capabilities of the Eos SAR, particularly acquisition of cross polarized and high incidence angle data, depend on the altitude of the platform on which the SAR flies and improve significantly at lower altitudes. The Eos SAR will provide a unique new data set and will play a key role in understanding the Earth's global processes alone and synergistically with other Eos instruments.