Prober Deployment Strategies for Resource Utilization on Small-size Asteroids

Asteroids smaller than 100 m exist extensively in space. They are easy to access and require less energy to land or lift off due to weak gravity, which makes them potential targets for resource utilization or asteroid mining. In the meantime, the small-size asteroids have distinctive dynamical environments due to strong perturbations from solar radiation pressure (SRP) or third-body gravity. Some of the asteroids even have a fast spin rate, which makes significant challenges for probers orbiting or landing on them. In this paper, we investigate the potential prober deployment strategy on small-size asteroids in both orbiting and landing situations. Firstly, the surface environment of the asteroid is discussed. The geometric and geopotential topographies of small-size asteroids are studied under different shape models. The surface escape and lift-off velocities, which determine the minimal tangential and normal velocity to escape the asteroids are studied. Combined with surface terrain, a landing site selection strategy is proposed and the stable regions that are suitable for prober landing are found. It is found that, the stable regions mainly located in the polar region of a faster rotator and gradually extent to middle latitude region as the spin rate decreases. Secondly, in considering the SRP, the orbital environment around small-size asteroids is discussed. The periodic orbits around equilibrium points and terminator/resonant terminator orbits in Augmented Hill Problem are designed. The stability of orbits under high-fidelity model are investigated and the potential parking orbits for prober deployment are found. Deployment and return trajectories to and from the ideal landing site are designed, which could be used as the channel for resource transfer. Finally, due to the uncertain surface parameters, prober might bounce on the surface which causes inevitable deployment errors. The deployment strategy by bouncing control is discussed. The prober reduces its landing error by changing the landing attitude to decrease the bouncing velocity. The strategy could be also applied to the sample transfer on the surface at different landing sites. This paper provides an option for resource exploration and utilization on small-size asteroids.