THE NEAR GUIDANCE AND CONTROL SYSTEM

he Near Earth Asteroid Rendezvous (NEAR) spacecraft guidance and control system supports all modes of pointing and control for the mission, including routine control during the long cruise to the asteroid Eros, high-frequency control of the propulsion subsystem thrusters during orbital corrections, precise pointing for science data collection, and spacecraft safety in emergencies. The attitude determination and control algorithms have been structured to provide the necessary capability, autonomy, high throughput, and relatively easy transitions among modes. The guidance and control system includes very few attitude sensors but achieves at least one level of redundancy for all reasonable failure modes. Its functions are divided between two redundant computers that are cross-strapped for maximum flexibility. (