Maintenance of Earth-Moon halo orbit

Halo orbit nearby the Earth-Moon libration points is valuable to explore the lunar farside, which however must frequently be controlled to stay in the vicinity of libration points because of instability. With a consideration of the high fidelity force models, this paper focuses on maintenance of halo orbit nearby the Earth-Moon libration points. First, based on the dynamic characteristic of libration orbit in the circular restricted three-body problem (CRTBP), the mathematic model and control strategy of maintenance are studied. A control method named circling-continuation is put forward including the Halo-style and Lissajous-style ways. Then, with the solar radiation pressure and third-body perturbation considered, maintenance of halo orbit nearby the Earth-Moon L2 point is investigated on the control interval and velocity increment. Additionally, the maintenance costs and efficiencies of two control styles are compared. The results show that the Lissajous-style way is suitable for the halo orbit maintenance with a control interval about 7.4 days and a velocity increment less than 20m/s. The circling-continuation method has been successfully applied to the Chinese CHANG'E-2 and CHANG'E-5T1 extended mission nearby the Sun-Earth/Moon and Earth-Moon L2 libration points, which has been proved to be efficient and fuel-saving and suitable to the future lunar and deep space exploration.