Maintenance of Relay Orbit About the Earth-Moon Collinear Libration Points

Relay orbits about the Earth-Moon collinear libration point shave significant valueon the exploration of the lunar farside, but have complex kinetic characteristics in the nature, thus the orbit maintenance has always been focused in the deep space navigation and control field. This paper explores orbit maintenance technology of the relay orbit about the collinear Earth-Moon libration points under the real dynamical conditions. First, based on the restricted three-body problem, the mathematic model of relay orbit station-keeping with the real dynamical model is analyzed. The continue-circling method is presented for the relay orbit maintenance with the two control styles, i.e., the Halo style and the Lissajous style. Second, with the third-body gravitation and the solar radiation pressure perturbations considered, the method is tested and analyzed by using the numerical simulations to achieve the control frequency and the corresponding velocity increment required by the relay orbits with different amplitudes. According to the simulations, the Lissajous style is suitable to the orbit maintenance with a control interval of 7.4 days and a velocity increment less than 20 m/s/a. Furthermore, the method has been successfully applied in Chang'e-2 and Chang'e-5T1 extended missions and can provide a beneficial reference for the future Chang'e-4 mission.