The Apollo 11 “Eagle” Lunar Module ascent stage was abandoned in lunar orbit after the historic landing in 1969. Its fate is unknown. Numerical analysis described here provides evidence that this object might have remained in lunar orbit to the present day. The simulations show a periodic variation in eccentricity of the orbit, correlated to the selenographic longitude of the apsidal line. The rate of apsidal precession is correlated to eccentricity. These two factors appear to interact to stabilize the orbit over the long term.

中文翻译：

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阿波罗 11 号“鹰”登月舱上升阶段的长期轨道稳定性

阿波罗 11 号“鹰”号登月舱上升阶段在 1969 年历史性着陆后被遗弃在月球轨道上。它的命运未知。此处描述的数值分析提供了证据，表明该物体可能一直保留在月球轨道上直到今天。模拟显示轨道偏心率的周期性变化，与顶点线的硒经度相关。顶点进动的速率与偏心率相关。从长远来看，这两个因素似乎相互作用以稳定轨道。