多目标小行星探测轨道整体化设计理论研究

Asteroid explorations are of scientific significance, of which orbit design is crucially one of technical challenges. Electric propulsion, planetary gravity assists, multi-target explorations, and some others are all praised highly but need experiments. This project studies systematic design of multi-target orbit design of asteroid explorations pushed by electric thruster. The time scale crosses from hours to years, and the space scale from meters to astronomical units. The dynamical model includes N-body gravitations, solar radiation pressure, and other main perturbations. These imply high nonlinearity. To utilize the impulse theory of orbit design, firstly, the quantitative equivalence between impulse and continuous thrust is studied. Secondly, the trajectory optimization theory pushed by continuous thrust is studied, which includes many inner constraints caused by events such as multiple planetary gravity assists and successive asteroid flybys, and constraint on control. Furthermore, gravity assists and flying-around asteroids are modeled as durative events, so that the orbit optimal design problem including many path constraints needs study. Finally, on the above basis, taking orbit deflection of potentially hazardous near Earth objects and asteroid exploration with flying-around and sample return as application prospects, optimal design theory is studied comprehensively. This project aims at a suit of general and effective theory and program on orbit design and optimization, so as to support orbit design of future asteroid explorations of our country.

小行星探测具有重大的科学意义，轨道设计是其中一项关键的技术难题，电推进、行星借力、多目标探测等是待验证而受推崇的技术。项目研究电推进作用下多任务小行星探测整体化轨道设计与优化的理论方法。探测轨道具有横跨小时到年、米到天文单位的时空尺度，动力学模型包括N体引力、太阳光压力等不同强度的摄动力，具有很强的非线性。为了使脉冲轨道设计理论用于连续推力推进，首先研究脉冲与连续推力之间等效的定量规律。再研究利用多次行星借力、中途探访多颗小行星的含有大量内点约束及控制约束的连续推力轨迹优化设计算法。进一步，将行星借力、小行星绕飞建模为过程问题，研究含有路径约束的轨道优化设计问题。最后，综合上述研究，以近地威胁天体轨道偏移、多颗小行星绕飞并采样返回等科学任务为背景，研究整体的轨道最优控制策略。旨在探索一套全面且高效的轨道优化设计的理论方法和计算软件，为我国未来的小行星探测提供轨道设计方面的理论

小行星探测具有重大的科学意义，轨道设计是其中一项关键的技术难题，电推进、行星借力、多目标探测等是待验证而受推崇的技术。项目研究电推进作用下多任务小行星探测整体化轨道设计与优化的理论方法。项目首先研究了脉冲与连续推力之间的等效问题，给出了等效关系式，用于求解GTOC7的问题，获得了第5名。其次，开展了复杂动力学模型和复杂控制约束下的轨道优化研究，对太阳帆连续小推力探测火星和小行星的时间最优轨迹优化问题进行了研究，得出了相关参数的影响特点，并以第六届全国空间轨道设计竞赛题为例，研究了多天体引力场模型下的小行星采样返回最优轨道设计问题。再次，开发了一种含多内点约束及控制约束的轨道优化设计算法，以GTOC7提交的结果为题，提炼后的结果能够提高项目组的排名，并且在GTOC8中获得了创造了国内最好成绩纪录——亚军。最后，工程应用性地研究了以火星探测为背景的绕火星及推广到绕类地行星的小推力人工冻结轨道和人工太阳同步轨道的优化设计问题，明确了绕水星、金星、地球、火星的人工轨道设计的异同。通过研究，项目组形成了一套全面且高效的轨道优化设计的理论方法和计算软件，能够为我国未来的小行星探测提供轨道设计方面的理论。