Hall Thruster Plume Interactions Analysis and Mitigation for Astranis MicroGEO Satellites

Astranis designs, manufactures, and operates MicroGEO satellites to provide internet access from geostationary orbit. Electric propulsion plays an enabling role by providing capability for orbit raise, stationkeeping, and slot relocation in a miniaturized bus.The unconventional electric thruster placement on MicroGEO spacecraft, in addition to their compact form factor, necessitates careful analysis of interactions between thruster plumes and spacecraft surfaces and design to mitigate resulting risks. If not properly accounted for, plumes may cause sputtering erosion of coatings, degradation of surface optical properties via deposition of eroded material, undesired torques and thermal loads, parasitic current collection by solar arrays, and attenuation of electromagnetic waves.Astranis has developed an in-house toolset to model interactions between plumes and spacecraft surfaces and uses this toolset to help drive spacecraft design.To validate analysis tools and characterize materials important to erosion and deposition, a ground test campaign is ongoing in which samples are exposed to the plume of a Hall thruster and permitted to deposit ultrathin films onto various substrates.This paper provides an overview of plume interactions characterization at Astranis, where rapid development makes analytical models and uncertainty management essential in addressing plume-induced risks. An analysis of the power and thermal system impacts of erosion and subsequent redeposition from a deployable reflector onto solar array and radiator surfaces on the MicroGEO Block 2 spacecraft guided hardware and operations design. The success of the bus design in avoiding problematic plume impacts has been demonstrated by completion of full electric orbit raise on multiple spacecraft.