Initial Results of Martian Electron Distribution Calculations Including a Nonuniform Magnetic Field

The Electron Reflectometer (ER) onboard the Mars Global Surveyor (MGS) satellite is intended to remotely probe the magnetic field of the planet. By measuring the velocity space distribution of fast electrons (10 eV < E < 20 keV), the spatial and temporal variability of the magnetic field topology far from the satellite can be deduced. Complicated distributions necessitate accompanying theoretical calculations to deconvolve the observations. Standard "two-stream" electron transport calculations, however, assume a uniform magnetic field and only resolve the pitch angle distribution into hemispherical grid points (up and down the field line). Accurate numerical reconstructions of the data, therefore, require a more sophisticated approach. Presented here are initial results of a time-dependent, multi-stream, kinetic electron transport model that includes the effects of a non-uniform magnetic field. Comparisons against MGS/ER data during the aerobraking phase of the mission, when the spacecraft sampled near-Mars space from well below the ionopause to beyond the bow shock, are shown to test the validity of the model.