Full successful ARTEMIS salvage mission overall

Abstract

Artemis spacecraft has been placed, on 12 July 2000, in an unplanned orbit for a partial failure following the Ariane 5 Flight 142 problem with upper stage. The selected mission rescue scenario, chosen for Artemis Salvage, has been the one that, involving a number of unusual operations, has offered the possibility to bring the satellite from the useless degraded injection orbit to the nominal geostationary position in a shorter time and using less propellant than possible. Whereas the initial part of the orbit-raising process, using chemical thrusters, was completed within a few days, the remaining part has taken more than 1 year and an half, requiring the ion engines to fire almost continuously. That is because the thrust of these engines is very weak and because only one of the four experimental ION thrusters has resisted at the long time firing. At first the liquid apogee engine using chemical propulsion has been used with five perigee firings to increase the apogee. The elliptical orbit has been then circularized by a number of apogee maneuvers resulting in a near circular parking orbit. The second rescue strategy has been selected for orbit raising mission using the satellite's electrical ion propulsion system, originally planned for station keeping maneuvers, leaving enough chemical propellant and Xenon to support several years of nominal operations lifetime. Thanks to the various and very complex strategies utilized, the satellite has been at first ‘spiraled’ from the circular parking position to an intermediate orbit using alternatively both south and north IPP thrusters, effecting also a partial inclination correction. Finally, due to the ION thrusters successive breaking, a continuous firing, initially with two thrusters and after with only one, has brought the satellite into the geostationary orbit. The recovery operation resulted in a certain number of unusual activities, in particular on the attitude control system for which a new operational mode has been designed. Embedded in a novel and remarkably flexible system design, used with outstanding ingenuity, team spirit and operational skills, Artemis’ propulsion capabilities proved to be the key to the rescue of an otherwise lost mission.