GIOVE-A's Fregat Disposal Assessment

Galileo will be Europe's own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. Following the approval of Galileo in 1999, a demonstration element was added - the Galileo System Test Bed (GSTB) with the GIOVE-A and GIOVE-B satellites - to allow early experimentation with the navigation signals and services before committing to the final constellation design. GIOVE-A (launched on 28 Dec 2005) and GIOVE-B (launched on 26 April 2008) were injected in the Galileo operational orbit (semi-major axis 29600 km, circular orbit, inclination 56 degrees) by direct injection with Soyuz/FREGAT launch vehicle.In order to mitigate future collision risks at Galileo altitudes, it was decided that all injected objects (FREGAT, and GIOVE/Galileo satellites at end-of-life) would be placed in higher-altitude disposal orbits. After separation from the GIOVE satellites, in both cases, FREGAT performed manoeuvres to move to a disposal orbit with a higher altitude. The disposal orbit was targeted as to minimize eccentricity growth and therefore maximize time for FREGAT to cross the operational orbit altitude. The objectives of this paper are: • To present an assessment of the FREGAT graveyarding actual manoeuvres with respect the target disposal orbit.• To present an assessment of the FREGAT actual disposal orbit evolution based on long-arc TLE fitting, taking into account accuracy of the fitting and of very long-term predictions.