Flyby Spacecraft Assisted Optical Navigation Method for Approach Phase of Asteroid Kinetic Impact

Kinetic impact is an effective strategy for deflecting near-Earth asteroids, where accurate autonomous navigation of the impactor during the approach phase is critical. This paper presents a flyby-spacecraft-assisted optical navigation method to enhance impactor state estimation. In the early stage of approach, monocular LOS measurements are integrated with radio ranging data from the flyby spacecraft to improve radial state observability. A navigation performance evaluation function is then constructed using the observability matrix of the linearized system, and combined with fuel consumption to optimize the flyby spacecraft trajectory. In the end stage of approach, asteroid surface features are extracted and matched using the ED-Line method, enabling frame-to-frame relative navigation. On this basis, an EKF is constructed for impactor state estimation, to achieve high-precision navigation. Simulation results verify that the proposed method significantly improves navigation performance and provides reliable support for precision impact missions.