ESA GNC Conference Papers Repository

PRISMA was launched on June 15, 2010 to demonstrate strategies and technologies for formation flying and rendezvous. OHB Sweden is the prime contractor for the project which is funded by the Swedish National Space Board with additional support from DLR, CNES, and DTU. PRISMA consists of two spacecraft: Mango and Tango. The Mango spacecraft is 3-axis stabilized and has a propulsion system providing full 3D orbit control. Tango is 3-axis stabilized with a solar magnetic control system and does not have orbit control capability. The two spacecraft were launched clamped together into a 700 km SSO and Tango was successfully separated from Mango on August 11, 2010. In April 2013, when both the nominal and extended mission phases were successfully completed, new objectives were assigned to the Mango spacecraft and the Tango spacecraft was shut down permanently. An eighteen month journey was started towards a new, non-cooperative space object to demonstrate rendezvous and inspection within an experiment called IRIDES (Iterative Reduction of Inspection Distance with Embedded Safety). The baseline rendezvous target is Picard. Since the start of IRIDES, the Mango spacecraft has completed a large series of optimized orbit manoeuvres that has put the spacecraft on a drift towards the new object. The rendezvous is expected in the second half of 2014 and will demonstrate optical relative navigation technologies and the characterization of the rendezvous object and its motion with the use of the on-board video system. The rendezvous strategy within IRIDES includes a series of collision free drift manoeuvres past the rendezvous object successively reducing the closest relative distance. The demonstrated technologies for this rendezvous are believed to play an important role in the future developments associated with space debris mitigation. The paper gives a brief introduction to PRISMA including a retrospective of the different achievements made in the mission. The paper then describes the optimized orbit manoeuvres made to acquire the drift orbit. The status of the drift finalization is then given where the initial manoeuvres performed to finalize the drift are described. The final part of the paper describes the planned activities within the rendezvous phase with focus on the IRIDES experiment.