With more and more missions around the Moon, a communication/navigation constellation around the Moon is necessary. Halo orbits, due to their unique geometry, are extensively studied by researchers for this purpose. A dedicated survey is carried out in this work to analyse the coverage ability of halo orbits. It is found that a two-satellite constellation is enough for continuous one-fold coverage of the north or the south polar regions but never both. A three-satellite constellation is enough for continuous one-fold coverage of both north and south polar regions. A four-satellite constellation can cover nearly 100% of the whole lunar surface. In addition, the coverage ability of another special orbit – distant retrograde orbit (DRO) – is analysed for the first time in this study. It is found that three satellites on DROs can cover 99·8% of the lunar surface, with coverage gaps at polar caps. A four-satellite constellation moving on spatial DROs can cover nearly the whole lunar surface. By combining halo orbits and DROs, we design a five-satellite constellation composed of three halo orbit satellites and two DRO satellites. This constellation can provide 100% continuous one-fold coverage of the whole lunar surface.

中文翻译：

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基于光晕轨道和远距离逆行轨道的月球通信/导航星座覆盖分析

随着围绕月球的任务越来越多，围绕月球的通信/导航星座是必要的。光环轨道，由于其独特的几何形状，为此目的被研究人员广泛研究。在这项工作中进行了专门的调查，以分析晕轨道的覆盖能力。人们发现，一个双卫星星座足以连续覆盖北极或南极地区，但不能同时覆盖这两个地区。一个三卫星星座足以连续覆盖北极和南极地区的一倍。一个四星星座可以覆盖近100%的整个月球表面。此外，本研究首次分析了另一个特殊轨道——遥远逆行轨道（DRO）的覆盖能力。研究发现，DROs上的三颗卫星可以覆盖99·8%的月球表面，在极冠处存在覆盖间隙。在空间 DRO 上移动的四颗卫星星座几乎可以覆盖整个月球表面。通过结合光环轨道和 DRO，我们设计了一个由三颗光环轨道卫星和两颗 DRO 卫星组成的五卫星星座。这个星座可以提供 100% 连续的一倍覆盖整个月球表面。