Missfit: Statistical Multi-Event Missed-Thrust Optimization for Low-Thrust Trajectories

We are developing a program, called Missfit, to design trajectories that accounts for unplanned thrust outages. These thrust outages result from routine and unavoidable anomalies that send a spacecraft into safe mode. While missed thrust events cannot be predicted, we do have statistical models that describes how likely they are to occur, which indicate that missions of significant length are likely to experience multiple MTEs. Using a novel approach that considers multiple events occurring during a mission, Missfit will give a mission designer the ability to set a desired probability of success and see the cost to the mission in terms of propellant or time. Equivalently, the user may optimize a probabilistic function, such as the 99th percentile propellant or time-of-flight. This approach directly targets mission risk---a topic of great importance to customers and review boards---rather than an arbitrary metric. Demonstrating that the risks to a mission are well-characterized and managed will help a project as it moves through its design phases, ultimately saving time and cost. Phase II funding will be used to continue development of Missfit, bringing it from a proof-of-concept state to a robust, tested, and documented software package that can be distributed to users. Target markets for Missfit include any entity planning a low-thrust electric propulsion mission. This includes the civil, commercial, and defense sectors.