Abstract: A sun-referenced safe-hold control system for momentum-biased satellites employs a safe-hold processor responsive to a set of sun sensors to detect attitude errors of the solar wings. Safe-hold processor provides independent control logic which rotates the solar wings to ensure that sunlight is maintained incident on the solar wings to maintain solar power in the safe-hold mode. In addition, the safe-hold processor provides independent control of the momentum wheel to place the spacecraft body in a passively stable nutational state. Passive nutational stability inherent in a momentum-biased satellite about two axes of the spacecraft enables the safe-hold processor to actively control the spacecraft about only one of its axes. The spacecraft safe-hold control system increases the period in which spacecraft health is guaranteed by adding active, closed-loop control of the solar wings.