Speaker
Description
Increases in the flux of high energy electrons in the Earth's radiation belts cause satellite charging which can lead to an electrostatic discharge, anomalies and disruption to service. For geostationary orbit (GEO) there are guidelines on how much shielding to protect electronic components, but not for lower orbits. Here we use data from GPS satellite NS41, the AE9 radiation model, and LANL satellite data to create a reasonable worst-case electron flux spectrum between 60 keV and 8 MeV. We calculate the charging currents for satellites in circular equatorial orbit between 4.25 and 7.0 Re and show that the recommended guideline of 2.8 mm (110 mil) of Al shielding is sufficient to keep charging below recommended guidelines at GEO. Approximately 4.5 mm (177 mil) of Al shielding would be needed for satellites in circular equatorial orbit at 4.5 Re. We show that the maximum electric field could exceed the breakdown field in cables and dielectrics just under the spacecraft surface on a timescale of 1-2 hours presenting a risk of anomalies. Radiation induced conductivity reduces the risk but is highly uncertain. A magnetic storm, series of storms or high speed stream accompanied by a large solar energetic particle event would present a much higher risk of anomalies on several satellites.
