PRISMA

Abstract

PRISMA is a precursor mission for formation-flying and on-orbit-servicing critical technologies. It consists of two spacecraft launched clamped together in low Earth orbit and separated in space after the commissioning phase in August 2010. The mission represents a unique in-orbit test-bed for guidance, navigation, and control (GNC) algorithms, novel relative navigation sensors (GPS, radio-frequency, vision-based), as well as new propulsion systems (high performance green propellant, micro-electro-mechanical). Originating from an initiative of the Swedish National Space Board, PRISMA is run by OHB Sweden with important contributions by the German Aerospace Center, the French Space Agency, and the Technical University of Denmark. After a brief overview of motivations, partners, and objectives, the chapter starts with a comprehensive description of the mission, including spacecraft platform, formation-flying and rendezvous sensors and actuators, as well as GNC key modes and algorithms. The discussion is followed by a summary of the main project phases, including overall schedule, verification process, and mission operations. Actual flight results from the basic PRISMA mission and its numerous GNC experiments are presented along with the achieved relative navigation and control accuracies over a broad range of autonomous operations between 30 km and nearly zero inter-spacecraft separation.