The proposed space mission Galileo Galilei (GG) utilizes Earth-orbiting test masses in high-speed co-rotation to test the Weak Equivalence Principle (EP). This paper presents the results of a technical evaluation of the proposal, as it was presented in September 1996. Investigation of the dynamics and control aspects reveals that the experiment is limited by the imperfections inherent in the practical implementation of the required drag-free control and stabilizing servo forces. The net consequence is a degradation of the EP measurement sensitivity by many orders of magnitude compared with the proposers' expectations.

This contribution to the calculation of spacecraft pointing and attitude measurement error budgets provides a rational method, based on Bayesian maximum a posteriori probability and related to maximum entropy principles, for the determination of probability distribution functions of the error components in these budgets. It takes into account the kind and amount of information on these error components that is usually available. It thereby improves on the conventional method, which assumes that all error components are normally distributed. Guidelines are provided for the choice of the confidence levels, i.e., the probability with which actual pointing errors must lie below the specified value. An example is given.

CorrespondenceClosed-form expressions are derived by field calculations for the drag force exerted by spacecraft eddy current dampers. These devices are conducting slabs moving at low speed in a narrow gap between magnets with a rectangular cross section. Finite edge effects of the slab are accounted for. The results can be used for design studies.

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