Investigation of Fixed Across-Track Baselines for Distributed Spaceborne SAR Systems

Abstract

Spaceborne Synthetic Aperture Radar (SAR) greatly benefits from distributed concepts. This work investigates the opportunity of establishing formations with fixed baselines. In particular, a fixed baseline in the across-track direction can enhance the performance of SAR interferometry for the generation of accurate digital elevation models or enable multi-platform range ambiguity suppression. Achieving a fixed across-track baseline requires a continuous forced solution of the relative motion, different from the Helix configuration, adopted for TanDEM-X, which relies on a natural solution of the dynamics. Continuous control is given by low-thrust engines, which continuously compensate for the natural oscillations of the relative motion in the across-track direction and maintain the desired spacecraft separation. This study aims to evaluate the feasibility of continuous control, in terms of delta-velocity budget, and the impact on SAR interferometric performance. The analyses yield promising results in terms of SAR applications and can be used for preliminary mission analysis and design, including both SAR and mission control considerations