The effect of aerodynamic lift on near-circular satellite orbits

Theory is developed to evaluate the effect of aerodynamic lift on near circular satellite orbits for: (i) flat surfaces at constant attitude to the velocity vector and (ii) sun-oriented plates. In both cases, the gas-surface interaction is restricted to diffuse or specular reflection; the former being particularly relevant to the height band where atomic oxygen predominates. An order of magnitude study is undertaken to determine the effect of lift on the solar panels of the ERS 1 satellite, due for launch around 1990. Calculations reveal radial perturbations of order 1 cm over a 5-day period for low to moderate solar activity. High solar activity, however, leads to a 10-fold increase in the order of this effect. Effects on stabilised satellites at lower altitudes are illustrated by a hypothetical study of the orbital inclination of Skylab 1.