A wheel of passive radar microsats for upgrading existing SAR projects

Almost-simultaneous radar images can be produced by a low cost system using a set of passive receivers onboard a constellation of micro-satellites using special orbital configuration. The combination of these images can improve the final resolution in range and azimuth and provide a systematic production of across-track and along-track interferometric data. The authors first review some of the technical peculiarities of these systems, linked to (1) the system, such as the chronogram, the orbital geometry and the required pointing, (2) the image quality, such as the ambiguity level, the required clock stability and the processing to higher resolution. They illustrate two applications of the concept in cooperation with the radar onboard the Japanese ALOS satellite or the ASAR instrument onboard the European satellite. They envision more focussed applications of the concept in simultaneous polarimetry and interferometry. Throughout the paper, they indicate the main features of the simplified radar payload that can fulfill the tasks while being light and small enough to be embarked on the generic micro-satellite spacebus that CNES specified.