Mission ObjectivesThe original objective of the EXOSAT mission was to use lunar occultation to obtain precise positional information for the relatively small number of X-ray sources then known. The mission made a number of significant scientific advances, including:
Mission NameEXOSAT = European X-ray Observing Satellite
SpacecraftEXOSAT was the European Space Agency's first three-axis stabilised spacecraft, with all three instrument packages co-aligned.
InstrumentsThe three instrument packages gave coverage between 0.05 and 50 keV. The LE (Low-energy imaging telescopes) had the highest sensitivity.
OrbitEXOSAT was placed in a 90 hours highly-eccentric Earth orbit, quite different from that of any previous X-ray astronomy satellite. The initial apogee was 191 000 km and the perigee 350 km. The science instruments were operated above 50 000 km, outside the earth's radiation belts. This allowed scientific operations for up to 76 hr per 90 hr orbit, without interruption.
Operations CentreGround station: Villafranca. Visible 76 hours out of 91 hour orbit. Scientific operations: European Space Operations Centre, Darmstadt.