Spacecraft Charging Effects by the High-Energy Natural Environment

Charging of dielectrics deep within spacecraft structures by the high-energy portion of the electron environment is investigated. Order-of-magnitude estimates of charging rates and saturation fields are made for spacecraft dielectrics and compared with breakdown thresholds. Results indicate that radiation-induced and natural conductivities of several spacecraft dielectrics are sufficiently low to permit charge accumulation to the point of dielectric breakdown. It is concluded that the high-energy portion of the natural environment can produce discharges and reasonably large replacement currents within the spacecraft structure and cables. Certain of the possible mitigation techniques proposed for spacecraft charging problems arising from the lower-energy portion of the environment may not be effective in protecting the spacecraft from the high-energy electron charging.