The German radar satellite TanDEM-X was successfully launched from Baikonur, Kazachstan, at 04.14 hrs CET on Monday, June 21, 2010. TanDEM-X joins its "twin" TerraSAR-X, which has been in operation since mid 2007, in its 514 km orbit. Together, the two satellites will spend three years collecting stereo radar data for a global digital elevation model of the Earth's entire landmass. This DEM will feature a relative accuracy of better than 2 meters (10 meter absolute) for a 12 meter grid. http://www.planetek.it/eng/products/all_products/terrasar_x