In flight performance of the zarm magnetic toruers MT90-1/MT140-2 flown on the abrixas mission

摘要

This paper deals with the in flight performance of the magnetic torquer assembly flown ond the German astronomical satellite ABRIXAS (A BRoad-band Imaging X-ray All-sky Survey). The attitude control system was designed to rely entirely on magnetic actuators from first attitude acquisition to three axis stabilization. A single momentum wheel has been added to provide stability. ABRIXAS has been successfully launched atop Russian COSMOS launcher from Kapustin Yar April 28,1999. After release of the satellite, telemetry could be established during the first pass above the ground station Weilheim (GSOC) located near Munich, germany. At the second contact engineers had noticed a sharp change in temperature in the main battery before the main battery failed. For the next two days the backup batteries (primary cells) have been used to keep the satellite alive. The backup system was designed to provide additional power for initial attitude acquisition and wheel momentum charging. Thus, the attitude control system was mostly not affected by the main battery loss. Housekeeping data have been received every two seconds. The system worked as expected from simulation runs performed prior launch. Shortly after battery discharge telemetry has been lost. The magnetic torquer assembly first flown on ABRIXAS are proofed by the received flight data but it is needless to say that the loss of the mission is a tragedy for the entire scientific team and all the people who worked on the project.