地月L2点周期轨道的月球背面覆盖分析

地月L2点附近轨道具备独特的动力学和运动学特性,是月球背面探测任务的中继卫星首选布设位置。面向未来月球背面探测任务的中继通信需求,分析并研究了地月L2点周期轨道(halo轨道)对月球背面的覆盖。在圆型限制性三体问题模型下,研究并给出了halo轨道族延拓计算方法,基于延拓法设计了地月系大范围南北halo轨道族;给出了中继卫星的月球背面覆盖计算模型,定义了相应的时间覆盖因子;数值仿真了地月系南北halo轨道族的月球背面覆盖情况。研究结果表明:地月L2点周期轨道幅值和类型决定其对月面的覆盖性,幅值较小的轨道的月面整体覆盖性较好,幅值较大的轨道对月球南北极覆盖较好,南北族轨道分别有利于月球南北半球的覆盖。文章研究可为我国"嫦娥4号"月球背面探测任务的中继星轨道设计提供有益参考和借鉴。

Coverage of Lunar Farside Surface of the Earth-Moon L2 Periodic Orbits

Orbits nearby the Earth-Moon libration points have the specific dynamic characteristicsand are the preferred position of relay satellites for the lunar farside exploration. For relay requirements of the future lunar farside exploration, the surface coverage of the Earth-Moon L2 periodic orbits is studied. Firstly, the continuation method calculating the halo orbit family is proposed with the circular restricted three-body problem. The south and north halo families with a large scope are calculated in the Earth-Moon system. Secondly, the coverage model of the lunar farside surface is presented for the relay satellites. The coverage factors are consequently defined. Finally, the coverage is numerically simulated. The results show that the coverage capacity is decided by the amplitude and style of L2 orbits. A halo orbit with small amplitude has an excellent entire coverage capacity, while a large one has a better coverage capacity for the south or north poles. Furthermore, the research can provide a beneficial reference for the orbit design of the future CHANG''E-4 mission.