Abstract
Small Satellites are establishing themselves as important tools for exploring our solar system. Developments in micro-electronics have enabled small and low-cost deep space probes to complement conventional space platforms in long-duration deep space missions. There is obviously an incentive to develop and enhance autonomous and robust guidance and control concepts for low-cost deep space missions. The paper presents a baseline design of an autonomous attitude determination and control system for a spacecraft performing a Near Earth Object (NEO) fly-by mission. During the spinstabilized escape phase, a single low-cost Sun sensor provides all information needed for the autonomous determination of the spin axis attitude pointing. Following the spin to three-axis transition, low-cost gyros in combination with a star sensor deliver the required attitude knowledge. The NEO encounter phase is the most critical mission phase with the attitude control performed by a cluster of small Control Moment Gyros (CMC's). The satellite needs to be rotated relatively fast to keep the NEO within its field of view for the imaging. The attitude knowledge is provided by a set of gyros and a star sensor. Simulations demonstrate the practicality and versatility of the proposed concept for low-cost NEO deep space missions.