A Formation Flying Concept for an Along-track Interferometry SAR Mission

Kurzfassung

While space-borne synthetic aperture radar (SAR) has evolved into a mature technology over the past two decades, there is a growing interest in interferometric SAR applications. Especially along-track interferometry with its capability to resolve the velocity of on-ground objects and ocean currents is of high interest for scientific applications. Since the accuracy of the resolved velocity on ground directly scales with the applied interferometric baseline and space vehicles are quite limited in size, a formation flying approach with two SAR instruments distributed onto two spacecraft appears to be an innovative approach to alongtrack SAR interferometry. In the framework of an ESA study, the present note discusses the potential benefits, drawbacks and problems associated with a close formation flight for an along-track interferometry SAR mission. To this end, the absolute and relative orbit reconstruction requirements for the SAR processing chain are derived from basic interferometric principles as well as appropriate baselines of the satellite formation in L-Band and X-Band. A discussion of potential space-borne navigation sensors is presented along with the accuracy of state-of-the-art relative orbit reconstruction. Finally, appropriate thrusters for formation acquisition and control are discussed together with approaches to formation flying guidance and control as well as fuel consumption.