Data analysis of the polar plasma environment for spacecraft charging analysis

Polar Earth orbit (PEO) is a peculiar orbit where energetic auroral electrons and low-temperature ionospheric plasma coexist. There is a risk of charging and subsequent arcing in PEO. The plasma environment, namely its density and energy, is the crucial parameter for spacecraft charging analysis. We statistically analyzed the environmental condition in PEO using the data of auroral electrons and thermal ions measured by DMSP (Defense Meteorological Satellite Program) satellites. The probability of a given combination of current densities of auroral electrons and thermal ions has been derived. The energy spectrum of the auroral electrons is also classified into several types, and its correlation with the thermal ions is analyzed. Combinations of the plasma parameters used by a spacecraft charging simulation software have been identified and a database containing the probability of occurrence of each combination has been formulated.

► We analyzed the aurora current density and background thermal ion in PEO using data of DMSP.
► We produced a database suitable for series of spacecraft charging simulations.
► Database is used to derive the number of charging events and primary arcs in orbit.
► Aurora current density exceeding 100 μA/m2 is possible with a probability of 0.01%.
► Aurora electron spectrum can be fitted by a double Maxwellian using the Genetic Algorithm.