Numerical Simulation of Atomic Oxygen Flux and Fluence Distribution on Spacecraft Surfaces in LEO Environment

A mathematical model has been developed for solving the atomic oxygen flux and fluence distribution on spacecraft surfaces in low Earth orbit space environment (LEO), based on Monte Carlo ray tracing and domain decomposition methods (MCRT-DD). The geometry of the spacecraft, the number density and molecular thermal motion of atomic oxygen, the spacecraft velocity affected by atmosphere co-rotation and orbit propagation parameters are considered in the model. Flux is calculated directly by integrating a differential equation and fluence is integrated by flux with orbit propagation. The results had shown that incidence angle plays an important role in affecting flux and fluence distribution. Maximum and minimum values are occurring in upwind and lee-wind direction separately. Calculated error is in agreement with the Long Duration Exposure Facility of National Aeronautics and Space Administration (LDEF-NASA) flight experiment data as well.