A system and method are provided for operating a control moment gyro (CMG)
in a spacecraft. The CMG includes a spin motor, and a CMG rotor that is
coupled to the spin motor and is configured to rotate about a spin axis.
Electrical power from a power source is supplied to the spin motor to
rotate the CMG rotor about the spin axis. A determination is made as to
whether the power source can supply sufficient electrical power to the
spin motor. If the power source cannot supply sufficient electrical power
to the spin motor, the spin motor is rotated by the CMG rotor to generate
and supply electrical power to the power source.