Patent ID: 7721998

Claim:
A spacecraft attitude control system, comprising: an attitude controller configured to selectively supply gimbal rate commands; a motion damping controller coupled to receive the supplied gimbal rate commands and determine if the supplied gimbal rate commands are available or unavailable; allow the supplied gimbal rate commands to pass for execution if the supplied gimbal rate commands are available; and supply modified gimbal rate commands that cause a gradual reduction of any spacecraft rotation to a predetermined quiescent state if the supplied gimbal rate commands are unavailable; and a control moment gyro (CMG) coupled to receive the valid gimbal rate commands and the modified gimbal rate commands and configured, upon receipt thereof, to rotate at the commanded gimbal rate about a gimbal axis, the CMG comprising: a rotationally mounted CMG rotor configured to rotate about a spin axis that is perpendicular to the gimbal axis, and a spin motor coupled to the CMG rotor and adapted to be selectively energized and deenergized, the spin motor configured to rotate the CMG rotor about the spin axis and, upon being deenergized, to be rotated by the CMG rotor and generate electrical power.