Lessons from Surveyor VI: Hopping Spacecraft for Low-Cost Surface Mobility on Small Bodies

There is great interest in missions to small bodies in our solar system such as asteroids, comets, Centaurs, dwarf planets, and moons. A key aspect of these bodies that makes them interesting is their varying morphologies over (and under) their surfaces. To characterize these bodies with in-situ exploration, a surface landing architecture is necessary that allows for the study of multiple diverse areas. Current stationary surface landers have only a short range, limited to capabilities of their on-board instruments and robotic arms. Surface rovers, while more mobile, are inherently more complex than landers and incur high costs both in development and operations. A surface lander capable of performing multiple hops could not only lower the cost of this mobility significantly, but also allow for the characterization of even more diverse areas than a rover. While a rover can cover tens of kilometers over the course of its lifetime, a hopper could potentially perform multiple hops of that same distance. While multiple mission concepts have been proposed (CHOPPER, Mars Geyser Hopper, GRUNT), and some have even flown (MINERVA-II, NEAR Shoemaker, Philae), the only mission to execute a planned hop on the surface of another body is the lunar lander, Surveyor 6. Performed in November of 1967, the results of this three-meter hop experiment contain lessons that will aid the development of future hopping mission concepts. This paper will first summarize previous hop attempts - both intentional and unintentional-and proposed concepts for future hopping spacecraft. A more in-depth study of the Surveyor 6 mission will be included, and lessons learned from the study will be applied to other small bodies. Analysis of ballistic, Surveyor 6-like hops, are performed for a diverse catalogue of small bodies including dwarf planet Ceres, comet 67P, and the moon Triton. Feasibilities of hops on each body are then evaluated based on distance and Δ-V, among other considerations. The utility of another style of hop, the “jump-and-wait” method, is also examined for the same bodies and compared to the Surveyor style hop results. The paper will conclude with a summary of the applicability of various types of hops for a variety of small bodies.