TanDEM-X Mission Status and Outlook on the Tandem-L Mission

The TanDEM-X mission consists of two satellites which fly in close formation to form a single-pass bistatic synthetic aperture radar (SAR) interferometer. It is used for the generation of the digital elevation model (DEM) of the global land surfaces and for scientific applications. The global TanDEM-X DEM has been completed in 2016. Since then bistatic operations continued for DEM updates and to capture dynamic changes of the Earth’s topography. A better understanding of these dynamic processes is the objective of Tandem-L, a follow-on mission proposal. It is based on two L-Band satellites featuring digital beamforming techniques in combination with large deployable reflectors enabling up to 350 km swath width and weekly global interferometric coverage. Such frequent observations are the precondition for monitoring dynamic changes in the biosphere (forest height, 3D forest structure, biomass), in the geosphere (deformation due to seismic and volcanic activities), in the cryosphere (sea ice extent, glacier flow velocity, volume and 3D structure), and in the hydrosphere (soil moisture, ocean currents) at adequate time intervals. Tandem-L aims at more than 25 higher level information products, among them are seven essential climate variables.