Navigation and Control of the PRISMA Formation: In-Orbit Experience

This paper presents flight results and lessons learned from the Spaceborne Autonomous Formation Flying Experiment (SAFE) conducted by the German Space Operations Center in the frame of the Swedish PRISMA technology demonstration mission. PRISMA involves two fully autonomous formation-flying spacecraft which have been launched in June 2010 in a dawn/dusk orbit at an altitude of 750 km. SAFE represents one of the first demonstrations in low Earth orbit of an advanced guidance, navigation and control system for dual-spacecraft formations. Innovative techniques based on carrier-phase differential GPS (Global Positioning System), relative eccentricity/inclination vectors and impulsive maneuvering are validated and tuned in orbit to achieve centimeter accurate real-time relative navigation, reliable formation keeping at the meter level and flexible formation reconfiguration capabilities. The technologies demonstrated within SAFE are considered as key precursors of future distributed satellite systems for unrivaled remote sensing and space exploration