Optimal design of Mars immigration by using reusable transporters from the Earth–Moon system

In the 2016 International Astronautical Congress, SpaceX's Mars immigration plan was first formally proposed alongside a fully-reusable transportation infrastructure. In the 12th edition of the China Trajectory Optimization Competition (CTOC-12) held in 2022, a Mars transportation trajectory design problem using reusable transporters from a parking distant retrograde orbit (DRO) in the Earth–Moon system was released. It is expected to transport as many immigrants as possible using a maximum of 50 transporters within a total of 20 years. The BIT-DFH-BJUT team reported a solution that can deliver 9080 immigrants to Mars, which ranked first in the competition. In this paper, the methods and results from the winning team are presented, primarily including an overall analysis, underlying round-trip trajectory design, and top-level scheduling. Specifically, a round-trip is divided into four phases, leaving the DRO to man-boarding at the perigee, Earth–Mars interplanetary transfer, Mars's return to the Earth, and return to the DRO. An overall optimization framework is constructed by synthesizing techniques such as data set creation and patching, differential evolution, nonlinear programming, greedy algorithm, and mixed-integer programming. Finally, we outline the final solution of our team and compare the results with those from the top five teams. This competition demonstrates that a large-scale Mars immigration plan is possible by using reusable transporters from the Earth–Moon system.