Numerical Model of Atomic Oxygen Interaction with Space Materials

Modifications of material surface properties due to interactions with ambient atomic oxygen have been observed on space structures surfaces facing the orbital direction in Low Earth Orbits (LEO). Some effects are very damaging to surface optical properties because LEO atomic oxygen possesses sufficient energy to break most organic polymer bonds and sufficient flux to cause oxidative erosion of polymers. At a certain energy level, atomic oxygen triggers chemical and physical reactions with materials, leading to surface degradation. The extent of degradation depends on factors such as spacecraft altitude, orientation, orbital inclination, mission duration, and solar activity variations. Atomic oxygen can also oxidize silicones and silicone contamination, resulting in non-volatile silica deposits. Such contaminants are commonly found on LEO missions and can pose a threat to the performance of optical surfaces. This work concerns the definition of a numerical model to study the erosion depth on the typically employed spacecraft material with fixed orbit parameters and mission duration. The Finnie model was chosen, and a limited number of parameters were considered to better understand and test the dynamics of the phenomenon. The results show the erosion depth of exposed materials over a 1-year simulation to highlight its magnitude and the potential impact on mission failure.