SOLAR-FLARE PROTON EVALUATION AT GEOSTATIONARY ORBITS FOR ENGINEERINGAPPLICATIONS

This work presents the results of novel analyses of spacecraft solar f lare proton measurements for solar cycles 20, 21, and 22. Solar events and cycles were classified and ranked by fluence and frequency of occ urrence, and events were characterized by the mean energy of the proto n spectral distributions, Spacecraft observations permitted a detailed study of event characteristics, such as special consideration of sola r minimum flares and cycle variability. Tables and curves are presente d to allow evaluations of potential threats to spacecraft survivabilit y at GEO, particularly for types of flare environments that emulate so lar cycle 22. Upsets for major events are calculated for several Bende l A parameter values and shield thicknesses, and effective energy thre sholds of events are determined as a function of these variables, Crit ical fluence levels, required to cause errors, versus A are presented, SEU's (single event upsets) of 93L422 devices on TDRS-1 are evaluated for various shielding conditions, Finally, upset dependencies on A an d shield thickness are correlated with event fluences for threshold en ergies of >30, >50, and >60 MeV.