Experiment of Autonomous Orbit Control on the DEMETER Satellite

An in-flight demonstration of Autonomous Orbit Control (AOC) will be carried out in 2004/2005 on the French micro-satellite DEMETER. The experiment aims at computing and performing station keeping maneuvers on board and autonomously. It is based on a TOPSTAR 3000 GPS receiver including the “DIOGENE” orbital navigator. In order to limit the impacts on the satellite platform, the maneuver computation software is installed in the GPS receiver, whereas the effective velocity and attitude maneuvering commands are generated by a dedicated piece of software installed in the payload management unit. This paper will first introduce the experiment and its context. Some simulation results will be shown in order to illustrate the expected long-term station keeping performance. Finally, newly obtained in-flight results of the navigation performance and of the maneuver computation software behavior will be presented. 1. EXPERIMENT CONTEXT CNES has for long been involved in activities related to on-board navigation, as proved by the successful inflight results obtained by the orbital navigators DIODE on SPOT4 and DIOGENE on HETE2 [3]. A research and technology program has been led by CNES since 1998 in order to demonstrate that on-board autonomy can be a good option for future missions. Part of this program is an in-flight demonstration of autonomous orbit control in 2004/2005 on the DEMETER satellite. DEMETER was successfully put in orbit on June 29th 2004 by a DNEPR launcher. The experiment implementation is still at an early stage, yet some first in-flight results have been obtained. Before showing them along with some other simulation results, the experiment and its context will be presented in details.