Higher altitude orbits (in the 500 to 20,000 km range) at the Moon are dominated by Earth perturbations and result in motions that do not ascribe to the standard notions of orbits dominated by nonspherical gravity effects (such as from oblateness). This fact complicates orbit design of lunar orbiter constellations that require specific and persistent coverage over a selected lunar region. Using a combination of analytical theory and numerical simulation, a technique is developed for designing a lunar constellation of three spacecraft where two spacecraft are always in view from the lunar surface for the polar regions.

中文翻译：

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冻结椭圆倾斜月球轨道的稳定星座

月球的高空轨道（在500至20,000公里范围内）受地球扰动支配，其运动并不归因于非球面重力效应（如扁圆度）支配的标准轨道概念。这一事实使需要在选定的月球区域进行特定且持续的覆盖的月球轨道星座的轨道设计变得复杂。结合分析理论和数值模拟，开发了一种用于设计三个航天器的月球星座的技术，其中两个航天器始终从月球表面看到极地区域。