Asteroid Approach Guidance Based on Predicted Rendezvous Probability

In order to determine the maneuver time and thrust magnitude autonomously, an asteroid approach guidance method based on predicted rendezvous probability is developed under the constraints of guidance precision and fuel consumption. Firstly, the concept of rendezvous probability is proposed to describe the probability of reaching the target asteroid. According to the covariance matrix of the spacecraft state estimate, the position error ellipse of the spacecraft on the B-plane is calculated. Considering the existence of non-Gaussian noises in the system, a probability density function is established using the rank sampling method. The probability of the target point falling into the error ellipse, that is, the rendezvous probability between the spacecraft and the target asteroid, is then evaluated by integrating the probability density function. By further introducing the rendezvous probability into the design of the engine switching curve, a trajectory correction strategy using constant thrust is designed based on the relationship between the predicted target-missing quantity and sight rotation angular velocity. The simulation results show that the proposed guidance law is of higher guidance accuracy and less fuel consumption than the traditional predictive guidance and error ellipse guidance.