Synthetic aperture radar in Europe: ERS, Envisat, and beyond

Following the successful Seasat project in 1978, the European Space Agency used advanced microwave radar techniques on the European Remote Sensing sat ellites ERS-1 (1991) and ERS-2 (1995) to provide global and repetitive obse rvations, irrespective of cloud or sunlight conditions, for the scientific study of the Earth's environment. The ERS synthetic aperture radars (SARs) demonstrated for the first time the feasibility of a highly stable SAR inst rument in orbit and the significance of a long-term, reliable mission. The ERS program has created opportunities for scientific discovery, has revolut ionized many Earth science disciplines, and has initiated commercial applic ations. Another European SAR, the Advanced SAR (ASAR), is expected to be la unched on Envisat in late 2000, thus ensuring the continuation of SAR data provision in C band but with important new capabilities. To maximize the us e of the data, a new data policy for ERS and Envisat has been adopted. In a ddition, a new Earth observation program, The Living Planet, will follow En visat, offering opportunities for SAR science and applications well into th e future.