电动帆轨迹优化及其性能分析

电动帆是一种新兴的无推进剂损耗的推进方式，利用太阳风的动能冲力飞行。电动帆由数百根长而细的金属链所组成，这些金属链通过空间飞行器自旋展开,太阳能电子枪向外喷射电子，使金属链始终保持在高度的正电位，这些带电的金属链会排斥太阳风质子，利用太阳风的动能冲力推动空间飞行器驶向目标方向。针对电动帆轨迹优化问题，提出采用Gauss伪谱法进行轨迹优化，克服了间接法对协态变量初值敏感的缺点。考虑在太阳风暴等原因造成特征加速度改变的情况，基于Gauss伪谱法实现电动帆在线轨迹重新规划，提高电动帆对太阳风不确定性的适应能力。最后以太阳系外探测任务为例，对电动帆和太阳帆的性能进行对比，仿真结果表明电动帆在星际远航任务中所用时间较短。

Electric Sail Trajectory Optimization and Performance Analysis

The electric sail is an innovative propulsion concept which uses the solar wind dynamic pressure to produce a thrust without the need for propellant mass. The electric sail is consisted of many metal tethers which are connected to a solar powered electron gun. The electron gun emits electrons to maintain the tethers at a high positive potential. The electric field generated by these metal tethers reflects the solar wind ions to generate a thrust. In this paper, the Gauss pseudospectral method is proposed for the trajectory optimization of electric sail. The Gauss pseudospectral method overcomes the shortcomings of the indirect method which is sensitive to the initial value of the costate variable. Considering the case of the characteristic acceleration changed under solar storms, the electric sail trajectory is generated online based on the Gauss pseudospectral method, thus improving the adaptability to the uncertainty of the solar wind. Finally, an outer solar system exploration mission is taken as a reference mission to compare the performance of electric sail and solar sail. The simulation results show that electric sail is faster than solar sail in the outer solar system exploration mission.