One of the key milestones of radar remote sensing for civil applications was the launch of the European Remote Sensing Satellite 1 (ERS 1) in 1991. The platform carried a variety of sensors; the Synthetic Aperture Radar (SAR) is widely cons- ered to be the most important. This active sensing technique provides all-day and all-weather mapping capability of considerably ?ne spatial resolution. ERS 1 and its sister system ERS 2 (launch 1995) were primarily designed for ocean app- cations, but soon the focus of attention turned to onshore mapping. Examples for typical applications are land cover...