There is an explosion of interest in the utilization of very low Earth orbit (VLEO, roughly 100 – 350 km altitude) for commercial and military purposes. Despite the obvious proximity advantages of VLEO, these altitudes have long been avoided because of the high density and harsh oxidizing environment of the residual atmosphere, which contains atomic oxygen (AO) and molecular nitrogen (N2). Momentum exchange in collisions between these species and satellite surfaces results in aerodynamic drag. Aside from drag, materials on the external surfaces of VLEO satellites may react chemically with AO, resulting in oxidation, erosion, roughening, and degradation of function. Minimizing and predicting drag and maximizing AO resistance are crucial for proliferated VLEO operation.

 We have used molecular beams of O and O2, traveling at orbital velocities of ~8 km/s, to investigate both the AO resistance and drag potential of various materials that may be used on VLEO satellites. The pulsed molecular beam, produced from a laser-detonation source, was used to expose selected materials to AO fluences up to ~1e021 O atoms/cm^2. Some of these materials were also exposed to the LEO environment on the International Space Station to similar AO fluences. Materials that exhibited significant AO resistance were used in molecular beam-surface scattering experiments, and the scattering dynamics were measured as a function of both polar (q) and azimuthal (f) scattering angles on pristine and pre-exposed sample surfaces. The velocity and angular distributions of scattered O-atoms depend strongly on the incident angle of the impinging atoms and the roughness of the surface in ways that have informed a new gas-surface scattering model, which has been parametrized for several satellite material surfaces, thus allowing for the determination of overall energy and momentum accommodation and for simulations of satellite drag.