太阳高纬探测器的借力飞行轨道设计

行星借力飞行技术可以节省深空探测任务的能量消耗.针对借助内行星引力向太阳高纬度发射探测器这一科学任务,分别以金星和地球为借力星体,运用圆锥曲线拼接法,通过求解兰伯特问题绘制能量等高线图,搜索多天体交会发射机会,设计探测器与借力体轨道周期之比为1∶ 1或2∶ 3的多次借力行星际轨道,获得相对黄道面成大倾角的目标轨道.分析表明,采用多天体交会借力相比单天体借力可大大降低发射能量;3次借用金星或者地球的引力可以使探测器轨道相对黄道面的倾角达到30°左右;3次地球借力轨道性能为最优,需要的地球发射能量更低,而且飞行器进入目标轨道之前的转移时间较短.

Trajectories to the far side of the sun via gravity assists

The interplanetary trajectories to the high latitude of the sun via gravity assists of inner planets were analyzed to reduce the energy cost of the space mission. Based on the patched-conic theory, the energy contour maps, which were used to search for the appropriate launch opportunities of multiple spacecraft and celestial body encounters, were plotted by solving the Lambert′s problem. The ratio of orbit periods between the spacecraft and the planet, such as Venus or Earth, was designed as 1∶ 1 or 2∶ 3 to provide repetitious gravity assists. Results show that, if inner planet gravity assists are used, the inclination of the object orbit relative to the ecliptic reaches about 30°at the most following thrice Venus or Earth gravity-assist flybys, and the "Earth-Venus-Mars-Earth-Earth-Earth" flight path which demands lower launch energy and shorter flight time is the optimal trajectory. Launching energy can be much reduced by multiple gravity-assist maneuvers than by single planet maneuver.