Preliminary design of the payload for the interferometric cartwheel

The interferometric cartwheel concept proposed by CNES, is based on a constellation of three micro-satellites with passive receivers on board, a conventional SAR satellite being used as the source of opportunity for the Earth surface illumination. The micro-satellite orbits are designed such that, at any time, the constellation provides a vertical and a horizontal baselines by selecting the appropriate pair of satellites. Therefore, the concept can be used for interferometric and super-resolution applications, and it avoids the temporal decorrelation inherent to repeat pass interferometry. ALCATEL SPACE is studying under CNES contract the design of the micro-satellite payload. Major drivers for the payload are low volume, low cost, and reuse of recurrent subsystems. This philosophy is fundamental to the success of the concept and it should also permit to add extra satellites to the cartwheel which improves the performance of the system. The proposed architecture of the payload is based on a unfurlable antenna reflector. The echo are received, digitized and recorded on-board without any preprocessing, except for data compression, and transmitted to ground. L, C and X bands have been considered for the preliminary design of the receivers. The paper recalls the principle of the cartwheel and it presents the architecture and the preliminary design of the payload including the antenna, the RF and digital subsystems and the telemetry