Onboard Mission Planning for Autonomous Avoidance of Spacecraft Subject to Various Orbital Threats: An SMT-Based Approach

The onboard mission planning problem for spacecraft is investigated in this article to autonomously avoid various orbital threats. First, the features of three typical orbital threats are analyzed, and a framework for autonomous avoidance of orbital threats is proposed. Then, the mission planning model is established, which can select different information flows depending on the threat categories and lighting conditions. During the planning, the discrete changes in the states of spacecraft are captured by the single happening. By transforming the happenings into the variables of satisfiability module theories (SMT), the constraints on duration and resource are described. On this basis, the planning problem of autonomous avoidance, which can be expressed as a finite number of happenings, is incorporated in the SMT formula. The mission planning solution is extracted from the satisfied assignment of the SMT formula via increasing the number of happenings iteratively. Finally, the simulations verify that the proposed strategy can achieve the autonomous avoidance of various orbital threats.