ASTERIA : Autonomous collision risks management

Abstract

For a few years now, CNES has been developing ASTERIA, an on-board autonomy concept combining autonomous station-keeping and collision risks management for Low Earth Orbit (LEO) satellites. ASTERIA, acronym for Autonomous Station-keeping Technology with Embedded collision RIsk Avoidance system, enables both in-track and cross-track control for different LEO missions. The on-board collision risk management process is fully integrated into the autonomous station-keeping in order to maintain the satellite orbit as best as possible and to minimize mission unavailability resulting from the avoidance maneuvers. Collision risk management requires the best possible knowledge of the future trajectory of the primary satellite, up-to-date information on secondary objects, as well as a calculation process with a large amount of data and the propagation of orbital states and covariance. That is why, so far, collision risk management has always been a ground segment activity. But this strongly limits on-board autonomy by imposing a timing and a knowledge of the station-keeping maneuvers not very suitable with a reactive Autonomous Orbit Control (AOC) system. On the contrary, management by the spacecraft itself offers interesting prospects for responsiveness and increased autonomy, but requires to carry out on-board risk calculation, to identify relevant risk assessments and to implement efficient avoidance solutions. The paper aims to show the completeness of the ASTERIA concept. First, the principles of on-board collision risk management are described. Then, the paper presents the study of the on-board computational load, the accuracy of risk estimation and the performance of risk avoidance strategies. The ability to operate such a system is then demonstrated through the study of the related operational management process. The concept has been tested and validated by in flight experiments on the ESOC OPS-SAT 3-Units CubeSat. Some preliminary results of this experiment are presented. Finally, the issues related to an autonomous system are discussed, particularly those concerning space traffic management.