The Formation Flying Navigation System for Proba 3

Abstract

PROBA-3 will demonstrate technologies and techniques for precise Formation Flying of two spacecraft. This paper describes its Formation Flying Navigation system for relative position and velocity determination. A Coronagraph spacecraft carries fine relative position metrology and higher-thrust propulsion, and an Occulter spacecraft carries fine low thrust actuators. The two spacecraft communicate data to each other through an Inter-Satellite Link with an associated delay. A relative GPS solution is also available for a period around the perigee pass. The Formation Flying Navigation system is part of the Formation Flying Software which commands the formation. It collects data from the sensors and actuation commands, synchronizes them to a common correction time, and processes them in an Extended Kalman Filter which makes use of a model of the dynamics of relative motion in elliptical orbits. This article provides an overview of the mission and the challenges posed to the relative navigation function design, and describes, in high level, the developed solutions that constitute the preliminary design of the Formation Flying Navigation System. Special emphasis is given to the solutions for handling the synchronization and processing of information from a high number of sources, in two spacecraft which communicate through an Inter Satellite link and are thus subject to significant latencies.