A Design Method of Multi-Window Launch Trajectories Design for Lunar Exploration Mission

Aiming at multi-window launch requirements as well as the target orbit's property of strong lunar perturbation in lunar exploration mission,a quick and efficient design method of launch trajectory is presented in this paper. During the launch phase before Spacecraft/Launch Vehicle(SC/LV)separation,each launch window has the same trajectory in the first and second stage flight sections,only the program angles of third stage work sections and the durations of coast sections need to be adjusted to satisfy injection requirements. During the orbital stage passivation phase,in order to raise the perigee altitude of orbital stage above GEO protected region,its velocity direction is properly modified with the help of lunar perturbation. This method can consolidate LV's status in first and second stage fight sections,reduce sub-stages' impact zones,strengthen the flexibility of injection parameter design,enhance the effieciency of injection parameter iteration and relative analyses,obviously improve the de-orbit effect of orbital stage,meet the requirements of space safety. This method can be applied to multi-window launch trajectory design for other deep space missions.