Duration: 36 months
Presently, the experimental investigation of gas-surface interactions and material erosion of spacecraft operating within Very Low Earth Orbit (VLEO) relies on dedicated atomic oxygen (ATOX) test facilities. However, three fundamental limitations are identified: 1) While the employed flow generators generally produce ATOX flows at representative particle velocities, they can provide only limited particle fluxes, which renders the screening of materials to be deployed in VLEO time-consuming and expensive. 2) These facilities do not provide the means of adding additional gas species to the flow, which severely limits their ability to emulate the chemical composition of the residual atmosphere over all relevant altitudes. 3) A small but significant and increasing degree of aerothermodynamic heating occurs as flight altitudes decrease, which cannot be replicated by contemporary ATOX facility designs. It is observed that flows generated in a Plasma Wind Tunnel (PWT) re-entry ground test facility fitted with an Inductively heated Plasma Generator (IPG) can potentially address all these aforementioned issues. Such facilities were originally optimised for the investigation of re-entry phenomena, specifically material responses, at altitudes below 100 km, with comparatively low flow velocities being offset by high internal energies and densities to ensure flight similarity in stagnation point heating. Owing to this traditional focus on the extreme environment of re-entry, the possibility of adapting the PWT method to investigate gas-surface interaction phenomena in VLEO has not previously been studied. This study shall assess the feasibility and trade-offs of extrapolating and scaling the PWT/IPG testing method towards the investigation of gas-surface interactions in VLEO-relevant environments. This may provide a valuable complement to dedicated ATOX facilities and provide a novel cost- and time-effective means of screening materials for long-term deployment in VLEO.
