Seminars

There has been a growing interest in very low Earth orbit (VLEO, dband communication. At these altitudes, drag from the residual atmosphere significantly accelerates orbital decay, and the predominance of reactive atomic oxygen (AO) leads to surface erosion of most materials. Protective coatings are therefore essential for long-term spacecraft operations in VLEO.
This study investigates how AO-induced surface roughness aIects orbital drag through roughness-resolved Direct Simulation Monte Carlo (DSMC) modeling. The approach combines experimental measurements of surface profilometry, obtained before and after AO molecular beam exposure under simulated VLEO conditions, with DSMC simulations in which the measured roughness is explicitly resolved by the computational mesh. The associated experimental work focusses on manufacturing material samples with germanium and gold coating on diIerent substrates and AO exposure and scattering measurements.
Preliminary DSMC results assuming perfectly specular scattering indicate that root- mean-square roughness in the range of 1–10 μm can alter drag by up to 25% relative to fully diIuse scattering. The computed angular scattering distributions show good agreement with experimental measurements. Initial AO fluence levels and corresponding erosion of germanium coatings exhibit negligible drag variation, though greater eIects are anticipated at higher fluences in upcoming experiments.