基于星下点机动的再入飞行器离轨规划

针对约束再入点地理位置的再入飞行器离轨问题，提出了一种基于星下点机动的离轨规划方法。再入飞行器的离轨轨道设计受到飞行器当前轨道状态和再入点参数的约束。首先，基于轨道飞行原理，建立了一般椭圆轨道冲量模型下离轨制动参数和再入点参数的关系，分析了最优离轨的推力施加原则；其次，在考虑地球自转的前提下，提出了直接离轨必要条件，针对约束再入点经纬度的问题，完善了利用非线性规划优化方法确定有限推力模型下离轨点位置的策略，同时给出了符合燃料最优目标的离轨制动参数；最后，探讨了一般情况下初始轨道不满足直接离轨必要条件时，为满足星下点约束而进行的轨道机动施加策略。

Deorbit planning of reentry vehicles using ground track manipulation

Aimed at the deorbit problem of reentry vehicles with constraints of reentry point location, a deorbit planning method using ground track manipulation is proposed in this paper. The deorbit trajectory design of reentry vehicles is constrained by the parameters of the real-time orbit and the aimed reentry point. First, based on the principles of orbital flight, the relationships between deorbit parameters and reentry point parameters are established with the model of impulse thrust in ellipse orbit. And the principle of thrust application for optimal deorbit is analyzed. Then, considering the influence of earth rotation and finite thrust, the necessary condition of direct deorbit is proposed. The strategy for determining deorbit location is developed with the method of nonlinear programming for the deorbit problem with latitude and longitude constraints of the reentry point. And the deorbit braking parameters conforming to the fuel optimal requirement are determined as a result. Finally, in the general case that the initial orbit does not satisfy the necessary condition of direct deorbit, the ground track manipulation method is proposed in terms of impulse thrust to satisfy the ground track constraints.