地月空间的远距离逆行轨道族及其分岔研究

地月系统中存在着一类绕月逆行、高度稳定的轨道族，称为远距离逆行轨道族(DRO)。以圆型限制性三体问题(CR3BP)为动力学模型研究了DRO轨道族周边的动力系统结构。利用Broucke稳定性图寻找分叉点，判断分叉类型，基于数值延拓计算分岔后产生的一系列新轨道分支。分叉类型主要有切分叉与多倍周期分叉(从3倍周期开始)，轨道维度包含平面轨道族与三维轨道族。计算新轨道族的特征，包括形状、周期、能量、稳定性、双曲流形结构等。探讨周期轨道的轨道周期与能量的关系，以几何化的方式展现分叉结构、多周期轨道的双曲流形结构等。该动力结构将为基于DRO轨道族的地月空间任务提供重要的理论支持。 

Distant retrograde orbits and its bifurcations in Earth-Moon system

There exists a type of stable retrograde orbit around the Moon called distant retrograde orbit (DRO) in the Earth-Moon system. The circular restricted three-body problem (CR3BP) is taken as the dynamical model to study the dynamical structure around DRO. It is possible to determine the bifurcation point and type using Broucke's stability diagram. The numerical continuation method is used to calculate several new orbital branches. Tangent and multi-period bifurcations are the two primary forms of DRO bifurcations (starting from period tripling). New orbit families include planar orbits and 3D orbits. The characteristics of the new orbit family are discussed, including shape, period, energy, stability, hyperbolic manifold structure. The relationship between orbital period and energy is discussed. The bifurcation structure and the hyperbolic manifold structure of multi-periodic orbits are presented geometrically. The dynamic structure will provide theoretical support for the mission based on DRO families.