Overview, testing and solutions to ESD-induced, solar-array string, on-orbit failures

Geostationary satellites have had sections of their high-voltage GaAs (and perhaps silicon) solar arrays fail abruptly on orbit. The recent (1997/8) occurrence of the problem was shown to correlate highly with active Geomagnetic-substorm activity (of the type that can result in spacecraft charging events) and thus was attributed to electrostatic discharge (ESD). A review of the cause and damage mechanisms of the effect is provided, along with the array requirements for this type of damage and the solutions to the problem. A comparison is made between several aspects of silicon and GaAs cells and how these could affect the probability of such damage. An extended discussion of the various points includes speculation about earlier solar-cell-string failures on silicon arrays.