Simulation of an auroral charging anomaly on the DMSP satellite

Observation of an operational anomaly on the Defense Meteorological Satellite Program (DMSP) F13 satellite has been reported by Anderson and Koons [1996]. On May 5 1995, the microwave imager experiment experienced a lockup of its microprocessor unit. This was attributed to the charging (and discharging) of thermal insulation blankets by energetic auroral electrons. DMSP is equipped with thermal and energetic charged particle detectors that measured the energetic auroral electron spectra responsible for the charging. A satellite frame potential of about -460 Volts was determined from the ion measurements. They presented calculations to show that the capacitance between the blanket surface and the spacecraft of an ungrounded .thermal blanket may be low enough to allow rapid charging, and that surface potentials of approximately -3 kV may have been attained in a period less than about 6 sec. Their approach however, does not account for the ion current collected by the charged surfaces. In this study, we have used the POLAR code to simulate the charging of DMSP at the time of the reported anomaly. POLAR is a three dimensional Fortran code that solves the PoissonVlasov system for self-consistent steady state plasma, density and currents around a charged spacecraft. The results indicate the highest potentials are achieved only by those few surfaces that have their ion collection restricted by the particulars of their location.