DSMC analysis of bipropellant thruster plume impingement on a geostationary spacecraft

Abstract

To quantify the potential contamination induced by exhaust plume from the MBB 10 N bipropellant thruster firing, we performed plume impingement analyses on the sensitive surfaces. The heat and mass fluxes of chemical species on the spacecraft surfaces and on the specific area of sensor units (optical port and radiator) were evaluated. A fully unstructured three-dimensional Direct simulation Monte Carlo (DSMC) code was developed and validated with measurements. A geostationary satellite with an optical port and radiator was selected and the actual configuration of the satellite was simplified by considering a bipropellant thruster, which is a major plume source to the sensitive surfaces, two communication antennas, and satellite panels. The DSMC computations show that the mass distribution or plume gas composition is unevenly distributed due to the mass separation effect, which occurs from the rapid expansion into vacuum especially around the nozzle lip at the backflow region. H2O is known as the most critical contaminant species; however, its plume impingement effect on the sensitive surfaces is negligible compared to the evaporation rate calculated by Langmuir's evaporation equation. Not only have the results contributed to the geostationary satellite development, but also these findings are expected to be significant in designing spacecraft configurations and useful in the trade-off studies