太阳中纬度探测共振借力轨道设计

针对太阳中纬度探测任务,设计了共振借力轨道方案.根据离开超越速度的解析表达式得到借力后日心轨道的可行集并将结论推广到任意借力行星.进而提出RRpInc图形化设计方法,通过RRpInc图分析得到共振借力的超越速度大小直接决定了最终轨道倾角.以共振借力行星作为目标星体设计借力转移轨道,以逃逸速度和到达超速作为性能指标,采用多目标优化算法优化.给出了两个设计方案:方案1选择金星作为共振借力行星,探测器通过"金星-地球-地球"借力飞行增加金星共振借力前的超越速度;方案2选择地球为共振借力行星,探测器在木星借力后返回地球共振借力.两个方案最终轨道倾角分别约为30°和35°.

Resonant gravity-assist trajectory design for Sun’s middle latitude exploration

Sun's middle latitude exploration targets on the observation of the solar middle-latitude region from inclined orbits. In order to achieve this, resonant gravity-assists trajectory(RGA) was investigated considering the constraints of nearest distance to the Sun. After the deduction of analytical expression of out-going excess velocity, dimensional normalization was performed in order that the results can be applied to any gravity-assist planet with proper scaling. Then a novelty graphical method for gravity-assist analysis was proposed as RRpInc graph, which visualized the relations in resonance ratio, normalized perihelion and inclination. From RRpInc graph, the magnitude of excess velocity was concluded to be the key parameter for final inclination. Thus several other gravity-assists should be carried out before RGA and optimized by multi-objective genetic algorithm for both minimum escape energy and maximum excess velocity at the beginning of resonant gravity-assist planet. Then RRpInc graph was used to get the proper resonant ratio. Two trajectory options are listed up as promising choices. The first option takes a flyby sequence of venus-earth-earth(VEE) before Venus resonant gravity-assists to the final inclination of 30?. The second option uses Jupiter flyby to speed up, which is followed by Earth resonant gravity-assists to reach an solar ecliptic inclination of 35?.