Satellite anomalies linked to electron increase in the magnetosphere

On January 20, 1994, at 1443 UT, the momentum wheel control circuitry of the Intelsat K spacecraft at geostationary orbit suffered an operational anomaly causing a loss of attitude control. The system was switched to the backup circuitry, and control was reestablished. The same day, at 1735 UT, the Anik E‐l spacecraft, also at geostationary orbit, suffered the same kind of operational anomaly in the momentum wheel control circuitry [ Rostoker , 1994]. According to newspaper accounts the next day, Telesat Canada operators struggled for 8 hours to regain control of the Anik E‐1 satellite. They were able to finally switch to the backup momentum wheel controller and resume reasonably normal operations.