GPS Based Precise Orbit Determination and Real-Time Navigation of the PROBA-2 Spacecraft

The PROBA-2 (Project for Onboard Autonomy) \nspacecraft is a micro-satellite serving as joint platform for \ntechnology demonstration and astronomical observations of the \nSun. The satellite is equipped with two kinds of GPS receivers: a \nminiaturized single-frequency receiver (Phoenix-XNS) \nsupporting the attitude and orbit control system and the first \nEuropean space receiver for tracking the civil GPS signals on \nboth the L1 and L2 frequency. Both receivers provide raw \nmeasurements for precise orbit determination on ground and are \nalso equipped with a real-time navigation system enabling \naccurate onboard positioning. The paper discusses the flight \nperformance of both receivers based on data collected during the \nfirst year of operation.