Lunar gravity assist is a means to boost the energy and C3 of an escape trajectory. Trajectories with two lunar gravity assists are considered and analyzed. Two approaches are applied and tested for the design of missions aimed at Near-Earth asteroids. In the first method, indirect optimization of the heliocentric leg is combined to an approximate analytical treatment of the geocentric phase for short escape trajectories. In the second method, the results of pre-computed maps of escape C3 are employed for the design of longer Sun-perturbed escape sequences combined with direct optimization of the heliocentric leg. Features are compared and suggestions about a combined use of the approaches are presented. The techniques are efficiently applied to the design of a mission to a near-Earth asteroid.

月球重力辅助是增加逃生轨迹的能量和C3的一种手段。考虑并分析了具有两个月球重力辅助的轨迹。应用了两种方法并测试了针对近地小行星的任务设计。在第一种方法中，将对日心轴腿的间接优化与对地心线相位的近似分析处理相结合，以解决短逃逸轨迹的问题。在第二种方法中，将逃逸C3的预计算图的结果用于设计更长的太阳扰动逃逸序列，并与日心小腿的直接优化相结合。比较功能并提出有关方法结合使用的建议。该技术被有效地应用于近地小行星的任务设计。