Automated Scheduling for TerraSAR-X/TanDEM-X

Abstract

In 2007 the satellite TSX-1 of the mission TerraSAR-X has been launched. Its primary payload is an active radar instrument, which shall supply radar images on request for commercial and scientific users. With a maximum load of up to 1000 datatake requests per day and an order deadline of six hours before uplink, the command generation process had to be fully automated. The complexity of the satellite and the evolving knowledge of its constraints exposed further challenges on implementation of the scheduling process. In 2010 a copy of TSX-1 has been launched: the TDX-1 satellite. When operating in close formation (i.e. distances of 250m-400m) this pair of satellites may execute stereoscopic datatakes which allow the generation of a digital elevation model. However several inter-satellite constraints need to be taken into account when operating at such short distances. Additionally we have two distinct missions, which need to be merged together: First, we have the old TerraSAR-X mission, for which the customers usually ingest their high-priority orders very late, for example for disaster monitoring. Second, we have the TanDEM-X mission, whose goal is a complete coverage of the earth in 3D with best possible accuracy. For this mission the datatakes are calculated up to one year in advance. This paper shows what techniques have been developed in order to cope with the challenging requirements of combining two missions and handling a two-satellites-system.