深空探测器多次引力辅助转移轨道全局搜索

介绍行星引力辅助近似模型,包括近行星点无动力和有动力两种方式;采用开普勒轨道拼接法与双脉冲Lambert算法,建立多次引力辅助转移轨道的参数优化模型;通过广度优先搜索算法对引力辅助行星序列进行穷举,对发射窗口和天体间转移时间进行离散化网格搜索,每一步网格搜索后均采用合理的定界剪枝方法,减少后续计算量。这种全局搜索方法不需要提前指定引力辅助行星序列,并可得到对应不同飞行时间以及不同引力辅助次数的搜索结果,获得若干多天体引力辅助转移轨道初步结果,为进一步局部优化设计奠定基础。文章给出几组全局搜索算例,得到从地球到火星、木星和土星的多次引力辅助转移轨道,验证了全局搜索方法的有效性。

Global Search of Multiple Gravity Assist Transfer Trajectories for Deep Space Probes

An approximate model of gravity assist is described,including two types with and without power exertion in planet’s periapsis.In terms of patched Keplerian orbits and Lambert algorithm,parameter optimization model is established for solving multiple gravity assist transfer trajectories.Exhaustive search of gravity assist sequence and discrete grid search of launch instant and transfer duration between planets are performed via breadth-first search algorithm,and reasonable bounding and pruning methods are used to reduce the successive computational loads after each step of grid search.This global search method does not need to specify the planetary gravity assist sequence in advance,and the solutions corresponding to different flight durations and different numbers of gravity assist can be obtained.Through global search,preliminary results of multiple gravity assist trajectories can be obtained for further local optimization.Finally,several design examples,including the multiple gravity assist trajectories from Earth to Mars,Jupiter and Saturn,demonstrate the effectiveness of the proposed global search method.