AERODYNAMIC TORQUE ON A SPINNING SPHERICAL SATELLITE WITH APPLICATION TO MEASUREMENT OF ACCOMMODATION COEFFICIENTS,

A spinning spherical satellite has been proposed by the Coordinated Science Laboratory to measure a general relativity effect which is predicted to cause the spin axis of the satellite to precess 5 to 7 sec of arc per year. Measurement of the precession is realized by a unique method or read-out which utilizes terrestrial sightings of sunlight reflected from mirrors on the satellite's surface. The measurement of such a small precession rate required an investigation of other torques producing effects which could possibly prevent the isolation of the relativity effect. In this respect, the analysis to determine the aerodynamic torque was initiated. The study consists of first obtaining the general analytical experession for aerodynamic torque which is found to depend upon the orientation of the satellite and the accommodation coefficient of the surface. Consideration is given to the effect of nonuniform distribution of accommodation coefficient and orbital regression effects which cause a change in satellite orientation with time. When these results are applied to the CSL satellite two conclusions are evident. These conclusions are discussed in the report and the feasibility of performing a satellite experiment to measure the accommodation coefficient by the technique proposed by the Coordinated Science Laboratory is investigated. (Author)