ABSTRACT
In the Gravity Probe B experiment [1], a superconducting rotating ball will be orbiting the Earth for over a year, and the drift of its axis resulting from two General Relativity effects will be measured. The drift is expected to be very small (0.042 arc-sec/year and 6.6 arc-sec/year in the East-West and North-South directions, respectively) and the measurement accuracy should be very high, so the classical (non-relativistic) torques causing the drift must be either eliminated or carefully accounted for. In particular, there will be quantum-size sources of magnetic field (fluxons) on the surface of the superconducting rotor which induce eddy currents and thus energy dissipation in surrounding normal metals. Consequently, differential damping torques are produced which must be estimated.
