Design And Optimization Of Low-Energy Transfer Trajectory For Libration Point Orbit

Libration points in the Sun-Earth system and Earth-Moon system are considered as suitable locations for performing space science missions and interplanetary exploration.In the complex dynamic environment of multi-body system,the low-energy transfer trajectory,combining with periodic and quasi-periodic orbit as well as their invariant manifolds structures,has attracted wide attention.It can significantly reduce fuel consumption and then possibly increase the ability of carrying payloads.Thus,analysis of the dynamic characteristics in three-body/four-body models and an effective design method are key points to gain the low-energy transfer.This dissertation was supported by the National Natural Science Foundation of China‘Nonlinear Orbital Dynamics and Trajectory Optimization in Non-Autonomous Four Body Problem'.The dissertation takes libration point orbits(LPOs)and invariant manifolds as the research objects,and studies the dynamic characteristics and optimization design method of the low-energy transfer trajectory deeply.The main research work focuses on the following aspects:The problem of constructing the transfer trajectory in the Sun-Earth system is studied.A design strategy of transfer trajectory with multiple constraints is introduced,and initial value functions are constructed based on the dynamic behaviors.The regions where the cost-efficient transfer exists are also discussed in detail.Firstly,a constraint model is given to describe the size and spatial orientation of the Earth parking orbit.The time departing the Earth is used as a free variable,which guarantees the convergence of the proposed design algorithm.In order to reduce the sensitivity of the initial condition,the initial value function is gained through the nonlinear data fitting.Finally,different amplitude and insertion points of the libration point orbits in conjunction with various constraint conditions are considered to deeply analyze the transfer performance.Preliminary results including velocity increment,flight time and departure time are discussed and the selected ranges of the insertion points for some special transfer trajectories are obtained.For the low-energy transfer in the Earth-Moon system,techniques associated with stable manifold and lunar flyby have been applied in the circular restricted three-body model and restricted four-body model.In terms of the periodic orbits around the different libration points,the useful constraint sets at perilune are established.The value ranges of the corresponding parameters are determined through a detailed analysis on the effect of lunar proximity.Meanwhile,the fuel consumption and transfer time are also calculated for the changed target orbits,which can find the optimal locations of inserting the LPOs.On this basis,the influence of the solar with different positions is examined to analyze the motion of the spacecraft.The impulsive and low-thrust versions of the fuel-optimal transfers between the LPOs are deeply exploited.A global search strategy is proposed based on the invariant manifolds construction.The adjusted states of the unstable and stable manifolds are studied to seek the suitable match point for maneuver application.Then the optimal method is adopted to further optimize velocity increment and obtain the complete optimal transfers in the considered three-body system.Additionally,the low-thrust transfers between periodic orbits with different energies in the vicinity of five libration points are designed.Optimization technique incorporated with constraint gradients is employed to further improve the computation efficiency and accuracy of the algorithm.To highlight the effectivity of the transfer scheme and analyze the properties,planar and three-dimensional low-energy transfers between different types of periodic orbits are explored.For the interplanetary transfer problem,the application of transporting a spacecraft from the LPOs in the Earth-Moon system to the Mars is investigated systematically.Two transfer types,incorporated with planetary gravity assist,are studied.One of them only employs the Earth gravity assist;and the other strategy combines both the Moon and Earth gravity assist.In order to gain the suitable trajectory and reduce the fuel consumption,a deep space maneuver is needed in the process of transporting the spacecraft to the Mars.Finally,the LPOs with different amplitudes are taken as study objects to be analyzed respectively.The best transfer opportunity is searched and confirmed in the given time range and the results indicate that the orbit transfer windows are quasi-periodic.