At approximately 2200 UT on 19 May 1998, the PanAmSat Corporation's Galaxy 4 spacecraft experienced a failure in its attitude control system (Automatic Pointing Control, APC). Unfortunately, the backup system also had failed, either at that same time or earlier, so that the operators were unable to maintain stable Earth-link [Space News, 25-31 May 1998, p. 3]. The Galaxy 4 spacecraft is a heavily used communication satellite at geostationary orbit; its sudden failure caused the loss of pager service to some 45 million customers as well as numerous other communication outages.