The TanDEM-X mission will survey all 150 million square kilometres of Earth's land surface several times over during its three-year mission. Apart from its high measuring-point density (a 12-metre grid) and high vertical accuracy (better than two metres), the elevation model generated by TanDEM-X will have another unrivalled advantage – being entirely homogenous, it will serve as a basis for maps that are globally consistent. Conventional maps are often fragmented along national borders, or difficult to reconcile as they are based on different survey methods or because of time lags between survey campaigns. Together TanDEM-X and TerraSAR-X are form the first configurable synthetic aperture radar interferometer in space. Besides this primary goal, the mission has several secondary objectives based on new and innovative methods such as along-track interferometry, polarimetric synthetic aperture radar interferometry, digital beamforming and bistatic radar. The TanDEM-X satellite follows the TerraSAR-X design with minor modifications such as an additional cold gas propulsion system (powered by high-pressure nitrogen gas) to enable fine-tuning of its relative position during formation flying and an additional S-band receiver to receive status and position information sent by TerraSAR-X. The TanDEM-X satellite has been designed for a nominal lifetime of five years and has a planned overlap with TerraSAR-X of three years. TerraSAR-X holds consumables and resources for up to seven years of operation however, potentially allowing for a prolongation of the overlap and the duration of the TanDEM-X mission.

Instrument: SAR (Synthetic Aperture Radar)
- 3 basic interferometric SAR observational modes (Bistatic, Pursuit monostatic, Alternating bistatic)

Sun synchronous
95 minutes
Cartography, land surface, civil planning and mapping, digital terrain models, environmental monitoring