Mixed-Initiative Planning for Space Exploration Missions

Modern planning and scheduling systems are capable of dealing with the size and complexity of many real world problems. However, mission critical planning is still often done by humans. Even if only a couple of plans are produced (“Master Plan” and “Plan B”), human experts evaluate multiple alternatives, think of contingencies, consider the likelihood of failure of various steps, and account for schedule slack and plan flexibility. Computers can evaluate thousands of alternative scenarios, but the solutions they ultimately produce are often not convincing enough for expert decision makers to trust human lives or mission critical operations to computer decisions. Further, automated systems often require significant changes in the way people operate, which in high-stakes high-pressure environments leads to rejection of the system by the users. In this paper we describe the decision support functionality of the Coordinated Multi-source Maintenance on Demand (CMMD) system. CMMD is designed to support the complete life cycle of mission plans for human space exploration, starting with initial long-term planning and ending with day-by-day execution of a detailed schedule. The goal of CMMD is not to replace human experts, but to assist them. To do so, CMMD explains reasons for commitments it makes, allows the user to interactively explore alternatives, guide the search toward more desirable solutions, and to run various queries (e.g., what courses of action have not yet been explored with respect to some goal?). We claim that giving users insight into workings of the system and gradually enhancing existing processes is crucial for gaining user confidence in produced plans and ultimately for adoption of the system.