The development of the ENVISAT-1 Advanced Synthetic Aperture Radar

The Advanced Synthetic Aperture Radar (ASAR) selected for the ENVISAT-1 mission of the European Space Agency, represents a sensor of paramount importance for the remote sensing community due to its enhanced flexibility with respect to the ERS AMI synthetic aperture radar. The unique combination of different spatial resolutions, incidence angles, swath width sizes and polarisation diversity will reflect in an increased number of operational modes tailored for a large set of scientific and operational applications. The use of an active antenna concept for tailoring the transmit and receive elevation beams to different mode geometry, a digital generation waveform technique for obtaining variable time-bandwidth products and a block adaptive quantization compression scheme are among the innovative design features of this radar. In this paper, the status of the ASAR instrument development are described, the accomplished project milestones are highlighted together with preliminary instrument performances.