Abstract: In order to determine the weak gravity field of irregular asteroids with 100 meters in international asteroid exploration mission, a gravity field measurement method based on visual navigation is proposed in this paper. Firstly, after completing three dimensional reconstruction, the optical navigation camera on the probe is used to measure three non collinear feature points of the known positions at intervals to obtain image information. Then the asteroid gravity constant and spherical harmonic coefficients are estimated by weighted least squares batch processing algorithm, which processes the measured data under the probe flight trajectories. Meanwhile, the flight trajectory planning of the probe is also analyzed, which shows that the flight path should be planned with the shape and mass distribution of the asteroid. Finally, the simulation results show that the proposed method can effectively measure the global gravity information of the asteroid in fewer flight paths.

Key words: asteroid, gravity field measurement, visual navigation, weighted least squares, flight trajectory