A Remote Agent Prototype for Spacecraft Autonomy

NASA has recently announced the New Millennium Program (NMP) to develop \faster, better, cheaper" spacecraft in order to establish a \virtual presence" in space. A crucial element in achieving this vision is onboard spacecraft autonomy, requiring us to automate functions which have traditionally been achieved on ground by humans. These include planning activities, sequencing spacecraft actions, tracking spacecraft state, ensuring correct functioning, recovering in cases of failure and recon guring hardware. In response to these challenging requirements, we analyzed the spacecraft domain to determine its unique properties and developed an architecture which provided the required functionality. This architecture integrates traditional real-time monitoring and control with constraint-based planning and scheduling, robust multi-threaded execution, and model-based diagnosis and recon guration. In a ve month e ort we successfully demonstrated this implemented architecture in the context of an autonomous insertion of a simulated spacecraft into orbit around Saturn, trading o science and engineering goals, and achieving the mission goals in the face of any single point of hardware failure. This scenario turned out to be among the most complex handled by each of the component technologies. As a result of this success, the integrated architecture has been selected to control the rst NMP ight, Deep Space One, in 1998. It will be the rst AI system to autonomously control an actual spacecraft. keywords: autonomous robots, agent architectures, action selection and planning, diagnosis, integration and coordination of multiple activities, fault protection, operations, real-time systems, modeling.