满足一定约束条件的登月飞行轨道的设计

讨论满足约束条件的登月飞行轨道的设计问题，将约束条件分类为只与太阳，月球，地球，飞行器和观测站之间的相对位置有关的运动学约束条件以及小及到飞行器轨道云动的动力学约束条件，在考虑登月飞行轨道的特征后，给出一种设计满足约束条件的标准飞行轨道的方法，并将方法应用于不同约束条件下的我国登月飞行以及月球卫星的轨道预测计。

LUNAR-LANDING TRAJECTORY DESIGNING UNDER CERTAIN CONSTRAINTS

This article presents a method to design a Lunar landing trajectory under certain constraints. The meaning of the constraints is analyzed and reduced to manageable forms. The constrains are classified into two categories: kinetic constraints deal with the relative configurations among Sun, Moon, Earth, spacecraft and tracking stations, while dynamic constrains concern the orbit of the spacecraft. Kinetic constraints generally select the launching dates of a month to satisfy the tracking network constraint and the landing hours of a day to satisfy the illumination constraint. Dynamic constraints reduce the 6 degrees of freedom for a spacecraft to 3 and impose limits on the adjustment of the 3 free parameters. To find the proper initial parameters for the trajectory search, a Lunar landing trajectory is approximately treated as a combination of two separate perturbed two body orbits. With the analytic solution for a two body problem and the numerical solution for a perturbed problem available , the search can be simplified by first requiring the trajectory enter the Hill radius of the Moon, and then fine tune the parameters to satisfy all the constraints. Although it is unlikely that the standard trajectory this paper obtains will be materialized due to the unrealistic constraints, as explained in the context, the method of searching standard flight trajectories can be generalized to treat other Lunar landing missions under different constraints.