LIAISON NAVIGATION IN THE SUN-EARTH-MOON FOUR-BODY PROBLEM

摘要

Liaison Navigation involves the use of scalar satellite-to-satellite tracking data to autonomously determine both the relative and absolute positions and velocities of a constellation of spacecraft. It was shown that Liaison Navigation worked well for spacecraft in halo orbits in the Earth-Moon three-body problem. In this paper, Liaison Navigation is simulated using libration orbits in the bicircular four-body problem involving the Earth, the Moon, and also the Sun. These bicircular libration orbits similar to halo orbits were computed using a multiple shooting method and initialized with a halo orbit computed in the three-body problem. Constellations of two spacecraft were placed in various bicircular orbits and crosslink range measurements were simulated. With those observations, orbit determination was used, and the resulting covariance matrix gave an estimate of the orbit determination accuracy. The fourth body gravity introduced large variation in the orbit determination accuracy which depended on the positions of the primary bodies. The average increase in error was about 3% over similar three-body halo orbits. When the Earth-Moon orbit plane is inclined with respect to the Sun-Earth orbit plane, the error was increased again by about 1%. Solar Radiation Pressure was included in the force model with no significant change in orbit determination accuracy. Estimating the reflectance of both spacecraft in a two-spacecraft constellation was possible to within 1-2% of the true reflectance. It appears that orbit determination error on the order of 10 m (1σ) could be achievable in actual operation.