This paper presents a spaceborne SAR mission concept in Ku-band for the measurement of the two-dimensional ocean surface current. The measurement concept is based on dual-beam along-track interferometry, which requires two highly squinted antennas each looking simultaneously in fore and aft direction. A single side-looking geometry and a ScanSAR imaging mode is chosen to complete the observational concept in order to achieve the requirements on revisit-time and coverage. The applied hybrid polarization is intended to increase the information level about different ocean scattering mechanisms. Furthermore a methodology of instrument requirement derivation is briefly discussed, ensuring the ocean current measurement accuracy requirements. Finally the instrument concept, including digital beamforming, and the SAR performance are presented. ... Read more