Heuristic Scheduling of Space Mission Downlinks: A Case study from the Rosetta Mission

Space mission planning/scheduling is determining the set of spacecraft activities to meet mission objectives while respecting mission constraints. One important type of mission constraint is data management. As the spacecraft acquires data via its scientific instruments, it must store the data onboard until it is able to downlink it to ground communications stations. Because onboard storage is limited, this can be a challenging task. This paper describes a formulation of the data downlink scheduling problem used for the Rosetta orbiter, a European Space Agency cornerstone mission currently investigating the comet 67P/Churyumov-Gerasimenko. We first describe the abstract problem and the Rosetta mission specific problem, along with desirable features of downlink schedules. We outline several algorithms (including the Rosetta operational algorithm) and we compare their performance on both actual mission data.