Killer electrons from the angry Sun did not stop the pagers

Abstract

On 19 May 1998 at 2210 UT, pager service in North America was interrupted. The cause was traced to a failure of a computer on board the Galaxy 4 (G4) spacecraft. Because the satellite failure followed an extended period of elevated high-energy electron flux that began earlier in April and May, electrostatic charging and discharging within the satellite initially appeared to be the cause of the failure. The failure of another (non-Boeing) satellite, Equator-S, earlier in the high flux storm strengthened the case for electrostatic discharge. The media picked up the story, reporting it in terms of "killer electrons from an angry Sun." However, killer electrons did not cause the failure. A review of the space weather experienced by G4 and other similar Boeing satellites since their launches forced the investigation team to conclude that space weather was not a plausible cause. The experience of Galaxy 4 is not unique. A review of satellite anomaly databases shows that the rate of nondamaging anomalies increases during periods of elevated fluxes of high-energy electrons, but, at an industry or fleet-wide level, there is no correlation of failures with electron flux. This article reviews the evidence that led the investigation team to reject space weather as the root cause of this particular anomaly. Copyright 2007 by the American Geophysical Union.