Cooperative optical navigation for asteroid exploration
- Paper ID
96750
- DOI
- author
- company
Northwestern Polytechnical University; Northwestern Polytechnical University，NPU; Beijing Minospace Technologies Co., Ltd
- country
China
- year
2025
- abstract
Asteroid exploration missions have become a focal point of research in the international aerospace field. Unlike other exploration missions such as those to Mars or the Moon, asteroid exploration presents unique challenges due to the small size, irregular shape, and significant uncertainty in the target characteristics of asteroids. These challenges include: (1) Asteroids' small size and irregular shape result in weak gravitational forces that vary rapidly in spatial distribution, requiring the spacecraft to overcome disturbances to its trajectory and attitude caused by irregular and weak gravitational forces. (2) The environment around asteroids is highly complex, with additional perturbations such as solar radiation pressure. (3) Due to the great distance from Earth, there is a significant communication delay between ground control stations and the spacecraft, necessitating an exact and autonomous navigation system for the spacecraft. Addressing the relatively low navigation accuracy issue when using a single spacecraft under uncertain asteroid ephemeris, this article investigates a cooperative optical navigation method for asteroid exploration. Firstly, a measurement model for two-spacecraft cooperative navigation is presented, using spatial pointing vectors and inter-satellite measurement information obtained by the two-spacecraft as observations. Based on orbital dynamics, the state transition matrices for each spacecraft are derived and combined with the error variance matrix, a robust Kalman filter is employed to estimate the position and velocity of the two spacecraft, achieving rapid positioning and velocity determination of the two spacecraft under inaccurate asteroid ephemeris. Secondly, by analyzing the observability and trajectory constraints of the two spacecraft cooperative navigation systems, a trajectory optimization method for the spacecraft based on observability analysis is proposed. Using the observability matrix based on LIE derivatives and incorporating the dynamics of the asteroid system, the observability of the two spacecraft navigation is analyzed. By optimizing the relative positions of the dual probes and the asteroid, the positioning accuracy of the navigation system is improved. Simulations demonstrate that when the asteroid ephemeris is uncertain, the navigation accuracy of a single spacecraft is low, whereas the cooperative navigation scheme of two spacecraft can effectively enhance the navigation accuracy. Compared to random trajectories without trajectory optimization, the navigation accuracy of the two spacecraft flying along optimized trajectories is significantly improved, with position determination accuracy reaching 15 m, meeting the requirements for autonomous navigation accuracy in deep space exploration.