Enhanced gas-surface scattering modeling for VLEO satellites in DSMC simulations

The Direct Simulation Monte Carlo (DSMC) method is a crucial tool for calculating the aerodynamicsof satellites in Very Low Earth Orbit (VLEO). However, DSMC simulations fall short in providinghigh-precision gas-surface scattering models. Implementing such model could vastly enhance missionplanning and fuel requirement calculations, ultimately extending operational lifetimes and reducingcosts. Moreover, the ability to utilize aerodynamic lift for altitude and orbit control reduces the needfor thrusters and fuel. Existing scattering models in DSMC can only capture the full complexity of theinteractions between gas and surface to a limited extent. Molecular dynamics (MD) simulations areexcellent for accurately modeling these interactions on a microscopic scale and provide detailed insightsinto the physical processes involved. However, due to computational limitations, it is not possible tosimulate the entire scale of a satellite with MD. We present an advanced modeling technique that is ableto use reflected velocity data points from MD simulations, to create a scattering kernel. This kernel,which represents a conditional probability density function, can be integrated into DSMC simulations,significantly enhancing their accuracy.