Pre-LOI trajectory maneuvers of the CHANG′E-2 libration point mission

This paper addresses pre-LOI (before Lissajous orbit insertion) trajectory maneuvers for the libration point mission of CHANG′E-2, which is the first Chinese satellite to fly to the Sun-Earth L2 libration point and the first satellite ever to fly to the L2 point from lunar orbit. First, a transfer trajectory for the mission is designed based on InterPlanetary Superhighway theory under the constraint of the remaining propellant, TT&C (telemetry, track and command) and sunlight conditions. The effects of trajectory maneuver errors on the mission are also analyzed. Second, based on the analysis results, the article investigates the trajectory maneuver schemes for the lunar escape and transfer trajectory maneuvers employing mathematical models and operational strategies. The mission status based on our maneuver schemes is then presented, and the results of control operation and corresponding analysis are provided in detail. Finally, the future trajectory maneuver in the Lissajous orbit is discussed. According to the analysis of the CHANG′E-2 TT&C data, the trajectory maneuver schemes proposed in the article work properly and efficiently.