Flight Results of the Precise Autonomous Orbit Keeping Experiment on the Prisma Mission

The Autonomous Orbit Keeping (AOK) experiment on the PRISMA mission was executed successfully from the 18th of July to the 16th of August 2011 and has demonstrated the capability of autonomous precise absolute orbit control. Using GPS-based absolute navigation data, AOK commanded thruster activations in the orbital frame to autonomously control the satellite’s longitude of ascending node (LAN) within a predefined window. The main performance requirement of the experiment was a control accuracy of the LAN of 10 m (1� sigma) with a maneuver velocity increment-decrement available budget of 0.5 m/s. After a 4-days commissioning phase, the reference orbit was acquired. A 3.5-days controller tuning was then followed by the fine orbit control phase started on the 30th of July until the end of the experiment. The control accuracy requirement was fulfilled. The mean value of the LAN deviation controlled by AOK was -3.6 m with a standard deviation of 9.5 m during the fine control phase. The total delta-v spent during the entire experiment was 0.1347 m/s corresponding to 27% of the maneuvers budget allocated. Digital Video System (DVS) data-takes on Earth have played an important role in the planning and execution of the AOK experiment as they mimic a remote sensing payload