TerraSAR-X and TanDEM-X After 13 Years of Joint SAR and DEM Mission

The German SAR satellites TerraSAR-X and TanDEM-X are in orbit since 2007 and 2010, respectively. This paper gives an overview about the challenges faced by such long-enduring missions, recent measures taken to preserve the satellites and to continue the mission, and major lessons learned for future SAR missions.