小行星探测轨道设计与优化技术研究

发布时间：2018-07-16 18:16

【摘要】：随着我国深空探测持续向前推进,开展对具有独特科学价值的小行星的探测已经成为深空探测技术发展的必然趋势。双小行星系统是众多小行星类群中的一种特殊形式,大约有16%的近地小行星和主带小行星属于双小行星系统,该类小行星是我国未来小行星采样返回任务的首选目标。本文以小行星探测和防御任务为潜在的工程背景,对小行星探测任务转移轨道设计与优化、弱引力双小行星系统引力场建模和双小行星系统附近轨道动力学特性等进行研究分析。首先,基于指数正弦曲线形状法并利用遗传算法对小推力小行星转移轨道进行了初始设计,继而采用Radau伪谱法和序列二次规划算法对小推力转移轨道进行了优化。采用指数正弦曲线法进行小推力转移轨道初始设计的关键是求解飞行时间约束方程,本文改进提出了一种计算效率好且计算精度高的指数拟合法。然后,采用复杂度和精度依次递增的球体-球体模型、椭球体-球体模型和改进的限制性椭球体-椭球体模型对双小行星系统的引力场进行建模,并对不同引力场模型下的双小行星系统平动点位置坐标偏差和三角平动点的稳定区域变化规律进行了对比分析。针对引力势函数模型中椭圆积分难以计算这一问题,采用了计算效率高、无积分环节的二阶二次球谐函数模型来进行引力势计算,并比较验证了其计算效率和准确性。最后,本文采用构造流函数方法来计算分析不同模型下的双小行星系统共线平动点李雅普诺夫轨道及其不变流形。该方法不用求解近似解析解来作为计算初值,也不用求解状态转移矩阵,便于编程实现。在李雅普诺夫轨道及其不变流形的基础上,利用不变流形的渐进性和方向性,设计了不同模型下的双小行星系统捕获轨道和逃逸轨道;并且,进一步借助不变流形及其异宿连接,采用庞加莱截面法设计了双小行星系统不同模型下的不同共线平动点李雅普诺夫轨道之间的低能转移轨道。
[Abstract]:With the development of deep space exploration in China, the exploration of asteroids with unique scientific value has become an inevitable trend in the development of deep space exploration technology. Double asteroid system is a special form of many asteroid groups. About 16% of near-Earth asteroids and main belt asteroids belong to double asteroid system. This kind of asteroid is the preferred target for future asteroid sampling and return mission in China. Based on the potential engineering background of asteroid exploration and defense mission, this paper designs and optimizes the transfer orbit of asteroid exploration mission. The gravitational field modeling of the weak gravity double asteroid system and the dynamic characteristics of the orbit near the double asteroid system are studied and analyzed. Firstly, the initial design of small thrust asteroid transfer orbit is carried out based on exponential sine curve shape method and genetic algorithm, and then the small thrust transfer orbit is optimized by Radau pseudospectral method and sequential quadratic programming algorithm. The key to the initial design of small thrust transfer orbit by using exponential sine curve method is to solve the time-of-flight constraint equation. In this paper, an exponential fitting method with good computational efficiency and high accuracy is proposed. Then, the gravity field of the two-asteroid system is modeled by the spheric-sphere model, the ellipsoid-sphere model and the modified restricted ellipsoid-ellipsoid model with increasing complexity and accuracy. The coordinate deviation of the moving point and the stable regional variation of the triangulated translational point in the two-asteroid system under different gravitational field models are compared and analyzed. Aiming at the problem that elliptic integration is difficult to calculate in the model of gravitational potential function, a second-order spherical harmonic function model with high efficiency and no integral link is used to calculate the gravitational potential, and its calculation efficiency and accuracy are compared and verified. Finally, the Lyapunov orbits and their invariant manifolds of two asteroid systems with collinear translational points under different models are calculated and analyzed by using the method of constructing stream functions. This method does not need to solve the approximate analytical solution to calculate the initial value, nor need to solve the state transfer matrix, so it is easy to be realized by programming. On the basis of Lyapunov orbit and its invariant manifold, using the asymptotic and directivity of invariant manifold, two asteroid systems under different models are designed to capture orbit and escape orbit. Furthermore, with the help of invariant manifolds and their heteroclinic connections, the low energy transfer orbits between Lyapunov orbits at different collinear translational points under different models of double asteroid systems are designed by using the Poincare cross section method.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V412.41
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本文编号：2127228