Two long-term stationkeeping methods for real Earth-Moon libration point orbits

Dynamics of the Earth-Moon system is more complex than the Sun-Earth system when a high-fidelity ephemeris model is adopted, which makes the long-term stationkeeping of the Earth-Moon libration orbits a challenging problem. This paper applies the LQR and the target point methods to this problem, and proposes a method for the coarse selection of control parameters. One typical Lissajous orbit around the L₂ point is taken as the nominal orbit for simulation. Results show that both methods are able to maintain the spacecraft in the close vicinity of the reference orbit, and the average yearly cost is below 1.5m/s with the current capability of the tracking accuracy. Compared with the LQR, target point method has a simpler form, and its control efficiency and robustness is higher as well.