Feasibility of noncontacting electromagnetic despinning of a satellite by inducing eddy currents in its skin. I. Analytical considerations

The servicing of disabled satellites requires that the units be despun before any repair can be done. This paper embarks on the feasibility study of an electromagnetically coupled despinning system based on inducing eddy currents in the satellite skin by an external dc magnetic field. The eddy current power input would act in such a way as to reduce the rotational energy of the satellite. The system does not contact the disabled satellite, and therefore, eliminates the hazards associated with physically attaching equipment, or astronauts with equipment, to the satellite. Two methods are investigated for inducing the eddy currents: (1) a large-diameter current loop positioned around the satellite such that the axis of the satellite rotation is in the plane of the loop, and (2) a magnet, either bar or U-shaped, positioned close to or surrounding the satellite. Closed-form solution for-the interacting magnetic flux, in terms of which the eddy current power input may be derived, is given for the two cases. Design parameters are evaluated for the two despinning systems in terms of input power and weight requirements