Review of SCATHA (Spacecraft Charging at High Altitudes) Satellite Results: Charging and Discharging

摘要

This report summarizes the major results from the SCATHA (P78-2) satellite charging monitors and discharge detectors. The data show that surface charging, near synchronous altitudes, occurs preferentially in the midnight to local morning sectors, as expected. Evidence for bulk charging by energetic electrons is also observed. The material-charging data show that there was a marked increase in bulk conductivity of solar-illuminated Kapton with exposure time in the space vacuum. Teflon accumulated a permanent charge that slowly increased with time, and a quartz cloth material charged to higher than expected levels; some of these material effects have now been simulated in the laboratory. The statistical picture of the surface charging and the resultant discharges and noise generation show a close association with each other. Some of the discharges are ascribed to possible bulk charging. The signal amplitudes of the discharges are discussed and the temporal character of the discharge signal is shown for a few cases. The results represent a new baseline in our understanding of satellite charging and its effects.