双小行星系统表面动力学环境分析

The binary asteroids are quite common in the solar system and are of unique scientific value. Studying the surface dynamical environment is the key to enabling surface roving exploration. The surface dynamical environment of the primary and secondary asteroid may be significantly affected by disturbances between them as compared to a single asteroid. In this study, the near-Earth binary asteroid system (66391) Moshup is taken as an example for the surface dynamical environment investigation. The polyhedral gravitational field models of the primary and secondary are adopted to establish the dynamical model of a point mass near the asteroid surface. The surface equivalent gravity and slope of the primary and secondary, as well as the minimum and maximum lift-off speeds, are calculated, and their distributions on the surface are analyzed. Much attention is focused on the periodical tidal effect of the secondary on the surface dynamical environment of the primary. Suitable areas on the primary and secondary for landing and roving are analyzed. Results show that the rotational centrifugal force causes the equivalent gravity to tend to decrease with latitude, and the slope is mostly dependent on the local terrain. The regions near the north pole of the primary and above the latitude of 80° of the secondary have small slopes and large equivalent gravity and are suitable for landing or roving. The tidal effect of the secondary has a periodic impact on the surface gravity of the primary. The minimum lift-off speeds in most areas of the primary surface are less than 0.3 m/s, while those in most areas of the secondary surface are between 0.10 m/s to 0.25 m/s. Due to the asteroid's rotation, almost all the directions of the minimum lift-off speeds are eastward.