A dynamical characterization of internally-actuated microgravity mobility systems

The in-situ exploration of small Solar System bodies (such as asteroids or comets) is becoming a central objective for future planetary exploration. Such bodies are characterized by very weak gravitational fields, which make hopping mobility platforms one of the preferred mobility strategies for microgravity surface exploration, as recognized by space agencies worldwide. However, little is known about the dynamical behavior of hopping platforms in low gravity environments, where small bodies' rotational dynamics can have a critical effect. Accordingly, the objective of this paper is to study in detail the “dynamic envelope” of hopping microgravity rovers, with a focus on internal actuation. Specifically, we first perform a static analysis with the goal of determining regions of a small body where an internally-actuated hopping rover can stably remain at rest. Then, we perform a dynamic analysis and discuss the actuation and instrument pointing performance of hopping microgravity platforms as a function of a number of system and environmental parameters (e.g., rover shape, body rotation rate). Finally, we tailor our analysis to a potential mission to Mars' moon Phobos. Collectively, our results show that internally-actuated rovers, from an actuation standpoint, are a viable mobility solution for a vast class of small Solar System bodies. Also, our analysis represents a key first step to develop path planning algorithms for microgravity explorers to safely explore dynamically feasible regions.