Spacecraft surface charging induced by severe environments at geosynchronous orbit

Abstract

Severe and extreme surface charging on geosynchronous spacecraft is examined through the analysis of 16Â years of data from particles detectors onâ board the Los Alamos National Laboratory spacecraft. Analysis shows that high spacecraft frame potentials are correlated with 10 to 50Â keV electron fluxes, especially when these fluxes exceed 1Â Ã Â 108Â cmâ 2Â sâ 1Â srâ 1. Four criteria have been used to select severe environments: 1) large flux of electrons with energies above 10Â keV, 2) large fluxes of electrons with energies below 50Â keV and above 200Â keV, 3) large flux of electrons with energies below 50Â keV and low flux with energies above 200Â keV, and 4) long periods of time with a spacecraft potential below â 5Â kV. They occur preferentially during either geomagnetic storms or intense isolated substorms, during the declining phase of the solar cycle, during equinox seasons and close to midnight local time. The set of anomalies reported in Choi et al. (2011) is concomitant with a new database constructed from these events. The worstâ case environments exceed the spacecraft design guidelines by up to a factor of 10 for energies below 10Â keV. They are fitted with triple Maxwellian distributions in order to facilitate their use by spacecraft designers as alternative conditions for the assessment of worstâ case surface charging.Key PointsA new set of severe space environments is compared to satellite surface charging mitigation guidelines at geosynchronous orbitNew severe environment electron spectra exceed the guidelines by up to a factor of 10 below 10Â keVSatellites anomalies previously reported are concomitant with the injection of high fluxes of electrons between 10 and 50Â keV