Ballistic Rendezvous Maneuver of an Asteroid Surface Probe and an Orbiting Mothercraft via Robotic Hopping

Future asteroid missions may require the transport of scientific samples or mining ore between the surface and an orbiting mothercraft. This paper introduces the concept of robotic hopping, a mechanical launch maneuver to achieve an orbital rendezvous from the asteroid surface, and characterizes the probe's fallback to the surface should capture fail. The feasibility of this maneuver is characterized through a Global Accessibility Map, which records, for each candidate launch site, the cost of an admissible transfer to the mothercraft, stationed at a natural body-fixed equilibrium point. The surface probe is modeled as a point mass capable of a directional jump, in which the launch impulse is generated through an instantaneous exchange of linear momentum with the surface. A guidance strategy is presented to determine the impulse vector, in both magnitude and direction, required to intercept a specified target set. This strategy exploits the natural dynamics of the asteroid's rotating gravity field, represented through a polyhedral shape model. A parametric sweep over the asteroid's rotation period further quantifies how spin rate affects the maneuver. The proposed maneuver is demonstrated on asteroid Ryugu, to date the only small body to have received a hopping surface-probe deployment. A Monte Carlo assessment shows that, while a nominal transfer exists from every candidate launch site, launch dispersions inflate the arrival cloud, suggesting that an open-loop intercept is not a viable capture architecture, and a controlled terminal rendezvous is required.