| Preliminary research for manned lunar landing mission has already begun in China, with trajectory design as the research foundation. As the mission trajectory of a manned lunar landing mission differs greatly from that of an unmanned lunar mission in many aspects, such as flight time, lighting constraints, earth re-entry, tracking requirements, mission abort trajectory, etc., methods of trajectory design for unmanned lunar missions can't be applied directly in the manned mission. So far there is very few open domestic literature on trajectory design of manned lunar landing mission, hence this issue is of great engineering application value and worth deep study from the perspective of mission constraints.In this dissertation, trajectory design and related issues, namely launch window and tracking conditions, are studied for the manned lunar landing mission. Firstly, characteristics of the Earth-Moon system and their influences on trajectory design are studied. Secondly, trajectory modeling, analysis and design, as well as launch window calculation, are investigated for translunar trajectory, transearth trajectory, free-return trajectory, and hybrid trajectory respectively, based on which the layout of ground tracking stations for manned lunar landing mission is studied. Lastly, cislunar cluster flight is preliminarily explored. The main contributions and conclusions of the dissertation are summarized as follows:1) The kinetic and gravitational characteristics of the Earth-Moon system and their influences on trajectory design and calculation are analyzed. Based on analysis of revolution and rotation of the moon, simplified calculation methods of the time of lunar eclipse and libration in longitude are proposed. Specifically research focus is set on the effects of different definitions of gravitational sphere of a small celestial body on trajectory calculation precision. The conclusions are: patched conics trajectories based on the Hill sphere and the sphere of influence are more accurate, but still have remarkable errors. As a result, the selection of gravitational sphere for patching has negligible influence for preliminary design and characteristic analysis.2) The issues of launch window calculation and translunar trajectory design for lunar soft landing mission are studied. An improved model for translunar trajectory calculation is proposed, which can merge lunar status information directly into the analytical model. Calculations and comparisons show that calculation accuracy can be improved without obvious change of model complexity. For unmanned lunar soft landing missions and manned lunar landing missions, a universal approach to calculate launch window of lunar soft landing mission is developed with multiple constraints considered, and calculation methods of launch window of each feature point are presented. The results show that the best launch opportunity lasts only one day per month under restrict lighting constraints. For the aforementioned two missions, design procedures of translunar trajectory are proposed respectively, with which both a preliminary design case and a precise design case are studied with given launch window conditions.3) Modeling, characteristics and design of transearth trajectory are investigated. Mathematical model of three-dimensional transearth trajectory is established, which takes only 3×10-4 seconds to calculate one transearth trajectory, so as to make it possible to compute a great number of trajectories with affordable calculation cost. According to comprehensive calculations of transearth trajectories using the above model, some characteristics of the trajectory are given: a) transearth trajectories that have same direction with rotation of the earth are more suitable for manned lunar landing missions; b) all trajectories escape from lunar sphere of influence on the east hemisphere, and the distribution area of the exit points is similar to an oval shape; c) selenocentric longitude of 80°E is the best initial value for trajectory design of an unmanned lunar freight ship, while selenocentric longitude of 40°E is the best initial value for trajectory design of a manned lunar landing ship; d) the transearth flight time can be shortened if the selenocentric inclination is chosen as 180°. With these analyses, effects of variables upon trajectory parameters are summarized in a comprehensive table, which can provide reference to adjust the design parameters of the trajectory. Lastly design procedures and case studies for manned lunar landing ships and unmanned lunar freight ships under multiple constraints are presented.4) Design methods of free-return trajectories and hybrid trajectories are investigated. Firstly free-return trajectories and hybrid trajectories are introduced briefly and analyzed qualitatively. Then an approach to design free-return trajectories satisfying certain constraints is proposed, with which a precise trajectory is calculated and can be treated as a nominal trajectory of the manned lunar landing mission. The flight procedure of the hybrid trajectory is discussed, and a typical flight case of a hybrid trajectory is designed based on the preceding nominal free-return trajectory.5) Tracking conditions of different layout of deep space tracking stations on manned lunar landing missions are analyzed, and then the idea of establishing deep space tracking stations in Polar Regions is proposed. Geometrical modeling and analysis of tracking condition for a deep space target is studied. Three layout schemes of ground deep space stations are compared, which include the layout of two domestic stations, the layout of one domestic station and one South American station, and the layout of one domestic station and one Antarctic station. The main conclusions are: a) tracking effect of the layout of two domestic stations is dissatisfactory; b) tracking effect of the layout of one domestic station and one South American station is better, but there still remains certain tracking gaps; c) combining with proper trajectory design, a single polar station may cover 100% tracking of the mission, but it is difficult to implement.6) The concept of cislunar cluster flight is proposed, and relative motion on hyperbolic trajectory and configuration of cislunar cluster are preliminarily discussed. Differences between cluster flight and distributed space system, such as formation flying and constellations, are discussed. A creative conception that employs cluster flight technique in the cislunar space is proposed. Its theoretical value and application value are illustrated, and a detailed future research plan is presented. Differential equations of spacecrafts relative motion on hyperbolic trajectory are derived. Design principles of hyperbolic hovering orbit and control method of station keeping are investigated. Laws of configuration changing of cislunar uncontrolled cluster are also analyzed. The calculation examples show that the configuration of the cislunar cluster changes gently and the base line length of the cluster is relatively steady under specific constraints.This dissertation may provide technical support for China manned lunar landing mission as well as stage two and three of China Lunar Exploration Program. The analysis of deep space stations layout may provide reference for TT&C system development of Mars exploration and other deep space explorations in the future. The discussion of cislunar cluster flight presents a brand-new mode for future deep space explorations.
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