Flight Results from PRISMA Formation Flying and Rendezvous Demonstration Mission

Abstract

The PRISMA in-orbit test-bed for Formation Flying and Rendezvous technology was launched on June 15, 2010. The Swedish Space Corporation (SSC) is the prime contractor for the project which is funded by the Swedish National Space Board (SNSB) with additional support from the German Aerospace Center (DLR), the French National Space Center (CNES) and the Technical University of Denmark (DTU). The PRISMA mission consists of two spacecraft: Mango and Tango, launched clamped together and separated in space. The Mango spacecraft is 3- axis stabilized and is equipped with a propulsion system providing full 3D orbit control capability. Tango is also 3- axis stabilized but with a simplified solar magnetic control system, and has no orbit control capability. The mission consists of a series of experiments mainly in the Guidance Navigation and Control (GNC) domain, demonstrating various aspects of formation flying and rendezvous which can be considered key technologies for future missions addressing tasks where multi-satellite technology must be mastered. The spacecraft are equipped with GPS, RFsensor and Vision Based navigation systems and has three different types of propulsion. The different GNC experiments are conducted by the participating organizations. These consist of Autonomous Formation Flying (based on either GPS or RF sensor), Proximity Operations with Final Approach/Recede Manoeuvres, and Autonomous Rendezvous. Interleafed with the GNC experiments, flight demonstration of the novel motor technologies are carried out. The first two weeks in space were allocated to a thorough system checkout on both spacecraft, with Mango and Tango still clamped together. Tango was then separated from Mango on August 11, after which real formation flying started. The formation control and safety heavily depends on the GPS based relative navigation system. The system has after certain adjustments proven to be stable and accurate down to sub-decimetre level in favourable conditions. By the beginning of September 2010, all essential equipment on the two satellites has been fully commissioned and the initial parts of the Autonomous Formation Flying in closed loop has been initiated. The mission will continue with more and more advance experiments up to a total experiment time of approximately one year. It is expected that propellant will remain after the nominal mission. The possibility exists to extend the mission with other innovative formation flying experiments.