载人登月绕月自由返回轨道存在性判据与月面可达域研究

To develop and utilize the lunar full resources is the preferred way for humans to explore the deep space, the circumlunar free-return orbit with high-safety is favored. The lunar gravitational swing-by mechanism and complex engineering constraints make it difficult to judge whether the circumlunar free-return orbit exists or not, and it is also difficult to accurately calculate the lunar surface reachable set of the low lunar orbit formed by tangential braking at the perilune point of the circumlunar free-return orbit. The existence criterion of the circumlunar free return orbit and the precision boundaries of its lunar surface reachable set are studied. Firstly, a set of independent design variables with low sensitivity and orbit design methods are established to facilitate the solution of the lunar surface reachable set. Then, the circumlunar free-return orbit are divided into two segments: the trans-lunar segment and the trans-earth segment, with the reverse and forward semi-analytical computing model, the relationship between the engineering constraints and the orbital design parameters are established, and the existence criterion of the circumlunar free-return orbit is designed. Finally, the boundaries of the lunar surface reachable set are calculated based on the circular restricted three-body model and the Hamilton system maximum principle, and furthermore, the evolution characteristics of the precision boundaries with the accurate dynamic model are calculated using the continuation theory. The research results can reveal the intrinsic properties of the circumlunar free-return orbit, and also make contributions to evaluate the selection feasibility of the lunar landing site for China's manned lunar mission in the near future.

全面开发利用月球资源是人类走向深空的必由之路，高安全性的绕月自由返回轨道倍受青睐，月球引力甩摆机理和复杂的工程约束导致轨道是否存在难以判断，也导致近月点切向制动形成的环月轨道月面可达域难以精确计算。项目研究一定工程约束条件下绕月自由返回轨道存在性判据和月面可达域精确边界求解问题。首先建立一组低敏感性独立设计变量及相应的轨道设计方法，便于求解月面可达域；然后将地月转移段和月地返回段拆分为逆向和正向两段分别半解析计算，建立约束条件与轨道设计参数影响关系，设计轨道存在性判据；最后，基于圆形限制性三体模型和Hamilton系统极大值原理计算月面可达域边界，并应用延拓理论和精确动力学模型计算可达域的演变特性。研究成果可揭示绕月自由返回轨道内在属性，也可为未来载人登月工程中月面着陆点选址的工程可实现性评估提供参考。

全面开发利用月球资源是人类走向深空的必由之路，高安全性的绕月自由返回轨道倍受青睐，月球引力甩摆机理和复杂的工程约束导致轨道是否存在难以判断，也导致近月点切向制动形成的环月轨道月面可达域难以精确计算。项目研究一定工程约束条件下绕月自由返回轨道存在性判据和月面可达域精确边界求解问题。建立了以近月点参数为设计变量的载人登月轨道设计模型，根据我国载人航天总体研究与论证中心提供的《载人登月轨道与窗口设计约束条件(V1.0) 》文件，设计了典型约束的载人登月自由返回轨道窗口存在性判据，可快速准确判定某时刻是否满足窗口约束条件，且证明了复杂约束条件下窗口并无明显规律可言，具体情况需要具体计算；基于环月交会支持的飞行模式，设计了着陆器地月转移轨道月面可达域分析计算方法和绕月自由返回轨道月面可达域分析计算方法。其中着陆器地月转移轨道月心LVLH坐标系中近月点倾角可在90~180deg之间分布，当倾角小于167deg时，升交点赤经只分布在80~140 deg和260~320 deg 之间，当倾角大约167deg时，升交点赤经可在80~320deg 之间连续分布，且分布区域都关于180deg对称。对于绕月自由轨道而言，月心LVLH坐标系中近月点倾角只能在168~180deg之间分布，当倾角接近168deg时，升交点经度只能在约130~170deg和290~330deg两个区间分布，当倾角接近180deg时，升交点经度歧义，理论上可在0~360deg之间分布。综上所述，典型约束的窗口存在性判据和月面可达域分析结论可直接支持我国未来载人登月任务飞行方案规划和月面选址。