Re-impact Guidance for Asteroid Defense Considering Multi-Debris Avoidance

The rubble-pile asteroid would be partially destroyed and produce numerous debris after an impact for asteroid defense. As the partially destroyed asteroid may still pose a threat to the Earth, a re-impact is required. The re-impact against the asteroid needs to consider the debris as obstacles. Aiming at the problem of re-impact guidance for asteroid defense considering multi-debris avoidance, an obstacle avoidance guidance method based on sequential B-planes is proposed in this paper. The basic idea is controlling the trajectory of the impactor by an analytical guidance law to achieve accurate impact with multi-debris avoidance. For the problem of multi-debris avoidance, a series of B-planes is arranged to group the debris. Only a small number of debris are considered in the fight of approaching the asteroid, which would help to reduce the burden of obstacle avoidance. Focusing on the problem of the short obstacle avoidance time, the initialization and correction model of guidance parameters are established. The impactor can take into account the information of future obstacles while avoiding nearby obstacles, and retain sufficient avoidance time in advance. Finally, the proposed re-impact guidance method for multi-debris avoidance is simulated. The results show that the proposed method can achieve multi- debris avoidance and impact the target accurately, with a high solving efficiency for guidance commands.