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 classification also in tropical zones and mo- toring of glaciers or urban growth. In parallel, international Space Shuttle Missions dedicated to radar remote sensing were conducted starting already in the 1980s. The most prominent were the SIR-C/X-SAR mission focussing on the investigation of multi-frequency and multi-polarization SAR data and the famous Shuttle Radar Topography Mission (SRTM). Data acquired during the latter enabled to derive a DEM of almost global coverage by means of SAR Interferometry. It is indispe- able even today and form any regions the best elevation model available. Differential SAR Interferometry based on time series of imagery of the ERS satellites and their successor Envisat became an important and unique technique for surface defor- tion monitoring. The spatial resolution of those devices is in the order of some tens of meters.