Study On Design Method Of Multiple Lunar Swingby Trajectories

The multiple lunar swingby orbit is a kind of large-scale orbit in the Earth-moon system.It has great application value in the deep space exploration.At present,the research on this kind of orbit is few.In this paper,the design method of the multi-lunar swingby orbit of the geomagnetic tail explorer is studied,including the following aspects:Firstly,the coordinate system and its transformation relationship are introduced.The Lambert problem and the state transition matrix(STM)which are based theory of orbit design are introduced.The influence of the swingby on the spacecraft's orbit parameters is analyzed.Secondly,based on the patched-conic method,the time of encounter of the spacecraft and the moon,the flight time of spacecraft in each segment are obtained by solving the time constraint equation.Based on the lunar position and flight time,the two-body Lambert problem is solved,and patched orbit in the inertial coordinate is obtained.Thirdly,multi-conic method and the pseudo-state theory are introduced.The advantage of multi-conic is analysed.The multi-conic method is applied to the initial state correction of the orbit,and the pseudo-state theory is applied to the modeling of the lunar swingby.The obtained orbit is a patched orbit under the restrictive three-body model.At last,the algorithm of reducing the velocity difference of patched is studied.The relationship between the patched point speed difference and the position vector and time of each patched point are deduced,and the relationship matrix is used to reduce the difference of patched point velocity.The research content of the paper can provide new means and methods for the future deep space exploration orbit design.It is of great scientific and engineering significance to further carry out the research of multiple lunar swingby technology.