The RADARSAT-2&3 topographic mission: an overview

The Canadian Space Agency and MacDonald Dettwiler are jointly conducting a study to define the mission capabilities and the operational performance of a RADARSAT-2/3 tandem interferometric mission. The primary objective of the mission is to provide a global digital elevation model of the Earth with quality comparable to the emerging US National Imaging and Mapping Agency High Resolution Terrain Information Level 3 (HRTI-3) specification; approximately 2 m relative height accuracy (90% LE) and 10 m nominal post spacing. The initial phase of the study identified a set of required modifications to the RADARSAT-2 spacecraft to support the tandem interferometric mission. These modifications have already been included in the design of the RADARSAT-2 spacecraft that is currently in Phase C/D of development and is scheduled for launch by the end of 2003. The RADARSAT-3 spacecraft would be a copy of RADARSAT-2 and be launched two years after to maximize the window of opportunity for the tandem mission. The two spacecraft would be flown with a separation of a few kilometres to gather interferometric data in a simultaneous monostatic and bistatic (SiMB-static) mode. At the end of the interferometric mission, the two spacecraft would be set apart to maximize the coverage of the combined system. This paper gives an overview of the tandem mission, and presents a summary of technical investigations carried out by MacDonald Dettwiler on the operating mode, the performance assessment, the orbit definition and the interferometric processing.