Two-stage guidance for autonomous transfer on asteroid surface

As a probe landing on the surface of the asteroid, the autonomous transfer needs to be performed due to the change of the target landing point. In this paper, a two-stage guidance method is proposed for the autonomous transfer problem on the asteroid surface, which contains an autonomous obstacle avoidance stage and a re-landing stage. Firstly, the trajectory optimization problem of the optimal fuel consumption is established, and the reference control profile is solved by Gauss pseudo-spectral method. On this basis, for the autonomous obstacle avoidance stage, an obstacle avoidance compensation term for the reference control thrust is designed, which has a collision threat warning function. For the re-landing stage, the ZEM/ZEV guidance method is designed with the time-to-gogo parameter satisfying the thrust constraint solved. Finally, the proposed guidance method is simulated using the 433 Eros asteroid model. The results show that the guidance method can realize the autonomous obstacle avoidance and the re-landing for the asteroid autonomous transfer mission.