Study On Transfer Trajectories Of Manned Lunar Exploration With LEO Space Station And Lunar Orbital Station As Spaceport

With the maturity of low orbit orbit(LEO)manned space technology and the preliminary development of LEO resources such as the International Space Station(ISS)and the future China Space Station(CSS),manned lunar exploration has once again become a hotspot of manned space activities among space powers since the 1960 s.Apart from the Apollo mission,various manned lunar exploration flight modes have been proposed nowadays,which pay more attention to their sustainability and reusability for the spacecraft,and are more inclined to carry out manned lunar exploration based on existing mature technologies and aerospace resources in LEO.In this context,three types of reusable manned lunar exploration flight modes are proposed,including the modes that take the LEO space station(LEOSS),the lunar orbital station(LOS),and both the LEOSS and the LOS as the spaceport,respectively.Aimed at the transfer trajectories of these three types of flight modes,this paper systematically and thoroughly carries out the modeling and characteristics analysis for the Earth-Moon-Earth transfer trajectories under the constraint of the cislunar space station,and tackles the key technology of the low-thrust Earth-Moon transfer which meets the demand of freight replenishment in these three types of flight modes.The main work of this paper is as follows:1.Providing the feasibility basis for the reusable cislunar transportation system.The cislunar space is divided into two parts: the space between the Earth's surface and the Earth's atmosphere,the space between the LEO and the Earth-Moon transfer space or the lunar space.From the perspective of velocity increment,the feasibility study for the reusable cislunar transportation system is carried out.The results show that when the load-mass ratio of single stage rocket is between 4% and 16%,it will be able to support missions between the LEO and low lunar Orbit(LLO)based on atmospheric deceleration,as well as the missions between lunar surface and the LLO.2.Design and characteristic analysis for transfer trajectories of reusable manned lunar exploration with LEOSS as spaceport.Based on the patched-conic model,an analytical design method for the Earth-Moon-Earth transfer trajectories constrained by the LEOSS is established.The characteristics of the orbital transfer window,the velocity increment and the total flight time are analyzed.Range of the accessible LLO is given in the Moon-centered fixed coordinate frame.A high-fidelity model is used to modify the parameters of the Earth-Moon-Earth transfer trajectories.3.Design and characteristic analysis for transfer trajectories of reusable manned lunar exploration with LOS as spaceport.Based on the patched-conic model,a fast iterative algorithm for the design of trajectories between the Earth and the LOS,is presented analytically.The convergence of the algorithm is presented,and the orbital transfer windows for the LOS with different inclination and altitude are analyzed.The Earth-Moon-Earth transfer trajectory design between the LEO and the LOS under the high-fidelity model is also completed.4.The research about the design of transfer trajectories between the LEOSS and LOS.Under the circular restricted three-body model,the concept of the reachable sets for Earth-Moon or Moon-Earth direct transfer are proposed,and the symmetry of the reachable sets is analyzed.Taking the Earth-Moon direct transfer as example,the reachable set of Earth-Moon direct transfer is given by solving the minimum-perilune Earth-Moon direct transfer trajectories.Based on the near-Moon three-impulse mathematical model,the design method for minimum-fuel Earth-Moon direct transfer trajectories covering the whole lunar is proposed,and the velocity increment distribution is given in the Moon-centered fixed coordinate frame.The characteristics of transfer trajectories between the LEOSS and the LOS are analyzed.5.The research about the design of low-thrust Earth-Moon transfer trajectories,which are used in the replenishment of cargo for reusable manned lunar exploration.Based on the Jacobi integral and zero-velocity surface,the sufficient conditions for lunar capture are established,and the guidance law of low thrust Earth-Moon transfer is proposed,including thrust direction,propulsion efficiency and flight control sequence.Then,based on the continuous dependence properties of the differential equation,the lunar capture set theories are proposed and proved,to ensure that the spacecraft is captured by the Moon.Finally,based on the lunar capture set theories,the low-thrust Earth-Moon transfer trajectory design is realized.The results show that the proposed low-thrust Earth-Moon transfer guidance law is robust to navigation errors and switching errors,and the design results are as good as the optimal solution in fuel consumption.Through the research of this paper,the transfer trajectories problems related to the manned lunar exploration flight mode with the cislunar space station as the spaceport are efficiently solved,and the theoretical and technical support is provided for the demonstration of the sustainable manned lunar exploration system.