Aerodynamic effects on an Earth orbiting satellite

Satellites orbiting the Earth experience both a lift and a drag force due to the atmosphere. Historically, only the drag force has been investigated. Lift and drag forces are both related to the gas-surface interaction between the atmosphere and the satellite. This study hopes to show that an improved model of the gas-surface interaction using a variable model for the normal and tangential momentum accommodation coefficients can increase the accuracy of orbit prediction programs. The orbit of the ERS-1 satellite was analyzed by comparing changes in the semi-major axis and eccentricity of the orbit with predicted changes using the traditional diffuse model and the improved variable model for the accommodation coefficients. It was found that although the variable model predicts much a much greater lift force on the satellite, improved modeling of the atmospheric density is need to accurately predict orbital perturbations. A procedure for incorporating a lift model into an orbit prediction program is suggested.