TerraSAR-X and TanDEM-X flying in close formation.
TerraSAR-X and TanDEM-X flying in close formation.
The TanDEM-X mission concept is based on the coordinated operation of two spacecraft flying in close formation. Using two independent spacecraft provides the flexible and reconfigurable imaging geometry required to meet the various mission objectives. For example, the primary goal of generating a precise digital elevation model requires variable cross-track 'baselines' – the distance between the satellites - of around 200 to 500 metres. At such short distances, collision avoidance becomes a major issue and a minimum safe distance of 150 metres perpendicular to the flight direction has to be maintained throughout the orbit.
