Spaceborne Bistatic Synthetic Aperture Radar

In order to maintain adequate swath overlap along the orbit, BSAR missions require careful selection of orbits and pointing which must also take into account system-level issues, for instance: impacts on transmitting/receiving radar mission, requirements on bistatic payload/bus, lifetime. This chapter presents an overview of candidate orbits for BSAR mission and highlights orbit design in the case of parallel orbits. In addition, a comprehensive analysis of attitude and pointing geometry is presented. A model is developed, which is applicable independently from the orbital configuration selected for the bistatic formation. The procedure is based on spherical trigonometry and allows effects of large, time-variant baselines to be accounted for, when different strategies are selected to share tasks and complexities between main mission and parasitic spacecraft. Basically, the model has been realized for mission analysis and simulation, as will be shown in the next chapter. However, it can also be applied to develop on-board software for real-time modifying pointing angles, using satellites positions as input, in order to attain swath overlap with predefined bistatic baselines.