The objective of the German satellite mission TanDEM-X is to generate a high-precision, 3-dimensional global digital elevation model of Earth’s surface in uniform quality. The TanDEM-X mission involves two almost identical earth observation satellites: TerraSAR-X and TanDEM-X. Both satellites fly in close formation at 514 kilometers altitude. The distance between them is slight and variable, sometimes even less than 200 metres. The two satellites record in a synchronized mode the land surface with two radar systems, which enables simultaneous acquisitions from different angles. This leads to precise elevation information with a horizontal grid of 12 x 12 meters and a vertical resolution of better than two meters in relative view and better than 10 meters in absolute view (Metzig and others 2008).
An unprecedented Antarctic database is also made available for investigating many science topics. In 2013 the inner parts of the Antarctic continent including the South Pole were also recorded using the so-called left-looking mode. At the 9th European Conference on Synthetic Aperture Radar (EUSAR) in 2012 the TanDEM-X Mission received a "Certificate of Recognition of TanDEM-X Achievements and Impact" in appreciation of the importance of the mission.
The radar instruments on the TerraSAR-X and TanDEM-X satellites provide a huge amount of data. Since storage capacity on the spacecraft is, however, limited, frequent downlink capability is a mandatory requirement. For polar orbiting satellites like TerraSAR-X and TanDEM-X this capability can be provided by satellite receiving stations located in polar regions. Polar stations have the advantage of being able to provide approximately 15 contacts a day to polar orbiting spacecraft, depending on their location. This is many more than is possible for stations in mid-latitude regions. Therefore, GARS O’Higgins can well meet the requirements of the TanDEM-X mission for very large downlink capacity.