flyby spacecraft assisted optical navigation method for approach phase of asteroid kinetic impact
- Paper ID
101786
- DOI
- author
- company
Beijing Institute of Technology (BIT); Beijing Institude of technology
- country
China
- year
2025
- abstract
Asteroid exist widely in near-Earth space, and is deep space target that threaten the safety of the Earth. Kinetic impact uses the impactor's high-speed impact to transfer momentum to change target orbit, is one of the most effective defense methods for small-size near-Earth asteroid (NEA). High-precision navigation of the impactor during approach phase is essential, which can provide accurate states information for the guidance and control system, and in turn enables accurate impact. The impactor's approach phase navigation is confronted with many difficulties. Firstly, the distance between impactor and the Earth is far, and communication delay of the deep-space network is large, so the navigation of the impactor needs to be autonomous. Secondly, the navigation methods that solely rely on optical cameras to obtain line-of-sight information from target cannot estimate the position and velocity of impactor in the radial direction. At the same time, in order to generate sufficient momentum, the impactor will fly fast in the approach phase, and the algorithm for the navigation system need to pay attention to both accuracy and real-time. To solve these problems, this study proposes a flyby spacecraft assisted autonomous optical navigation method. In the early stages of approach phase, the monocular camera is used to obtain line-of-sight measurement information of NEA, combined with the radio ranging information provided by the flyby spacecraft for integrated navigation, and the radial state of the impactor is estimated. On this basis, a trajectory optimization method for flyby spacecraft based on navigation information evaluation is proposed. Using the observability matrix of linearized system, the observability of the impactor state is analyzed, and the performance evaluation function is designed to optimize the trajectory of the flyby spacecraft. In the middle and late approach phase, the NEA is imaged as the surface target, and the texture features of the surface of the NEA is extracted and tracked using gray level co-occurrence matrix to estimate the inter frame relative state of the impactor, which is fused with the absolute state to achieve accurate state estimation of the impactor. At the same time, based on keeping the hovering observations of the flyby spacecraft, the observation geometry is analyzed, and the fast optimization selection method of texture features is established, which can improve navigation accuracy of the final impact section furtherly. The simulation results show that proposed method can effectively improve the navigation performance of the impactor during approach phase.