While the physical phenomena causing unbalanced changes in the state of energy within an orbital system are reasonably well understood, their effect on individual spacecraft are varied. The lessons learned in solving the problems of a given satellite can be broadly applied but the demands for a specific and detailed characterization of each new satellite cannot be circumvented for accurate results. There are a large number of effects which must be considered, and as orbit accuracies are successively improved, smaller effects grow in proportion to the total error budget.