Generic Computation Method of Free-Molecular Flow Effects on Space Objects

Abstract

This paper presents an analytical formulation and a computational method of free-molecular flow effects incorporating the temperature variation over the orbital motion of a satellite. The rarefied aerodynamics interactions, so-called free-molecular flow, has been studied for decades and the complexity of the phenomena has been the bottleneck. A new aspect of analysis on the surface temperature contributions is implemented in the analytical form. It affects the magnitude of momentum exchanges and thus the resulting force at the satellite surfaces. The free-molecular interaction perturbs the orbit and the attitude of a satellite as well as of any other orbiting space objects below the exosphere of the Earth, including International Space Station and space debris. The enhanced fidelity and accuracy of the atmospheric perturbation model is expected to complement with the growing requirements on the orbit determination accuracy of space objects, especially gravimetry missions. Under exemplary orbit and attitude conditions, temperature variations together with the free-molecular flow effects are obtained and discussed. The result indicates the magnitude of the force coefficient jump is around 6%, which is induced by the surface temperature variation.