High-precision physics-based radiation force models for the Galileo spacecraft

We present two new high-precision physics-based radiation force models for the In-Orbit Validation (IOV) and Full Operational Capability (FOC) spacecraft (s/c) of Galileo Global Navigation Satellite System (GNSS). In both cases, s/c bus surfaces are covered in material types, i.e., Laser Retro-reflector Array (LRA), Optical Surface Reflector (OSR) Single-Layer Insulation (SLI) coverings, that were either not encountered or specifically dealt with earlier work. To address this, a number modelling enhancements proposed tested, including: specific model to account direct reflected solar LRA surfaces; design update computation process allow more than one insulation material; thermal OSR Antenna (NAVANT) surface includes temperature derived from on-orbit measurements; emissions radiator panels on + X ± Y IOV FOC, - Z FOC only. UCL2+ each these effects accounted for. The theoretical impact concept introduced is assessed, individually, by considering magnitude its effect acceleration-space. orbit accuracy confirmed through rigorous set Precise Orbit Determination (POD) validation tests, which observations all active over full years, 2017 2018, including during eclipsing periods, included analysis. approach results day boundary discontinuities 22 mm, 17 mm 27 radial, across-track along-track components, respectively. Analysis one-way Ranging (SLR) residuals suggests radial at better 1 cm (3.7 mean residuals) precision 2 (17 root square (rms) error) achievable model.