Probability factors governing ESD effects in geosynchronous orbit

Case studies of classic distributions of anomalies experienced by operational satellites, due to surface charging (MARECS-A) and internal charging (DRA-/spl delta/), yield probability factors in respect to solar cycle, season, local time, geomagnetic activity and intensity of the outer radiation belt. Those derived relative frequency functions which depend upon electron incidence should have general applicability but others, which seem to be shaped by specific properties of the charge sites, still represent a useful base-line of ESD vulnerability.