A theoretical investigation has been made of the torques acting, as a result of electromagnetic interaction, on spherical conducting earth satellites. The analysis has been applied to the 41-meter-diameter satellite Echo II (1964 4A), which is in a near polar circular orbit. The calculations have yielded quantitative values for the accelerating and the decelerating torques. A probable explanation of the nearly constant spin rate of Echo II for a long period of time is that the eddy-current torque and the induction torque were in balance. Other torques are shown to be negligible in comparison with these two.

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