| After the successful completion of the lunar mission, Chang’e-2was transferred to the Sun-EarthL2point, making it the first spacecraft to carry out such a type of mission around the world, whichmeans higher requirements for orbit design and control. Compared to traditional two-body missions,the libration point mission always takes three bodies into consideration, which is also an N-bodyproblem in celestial mechanics. At present, except for N=2(i.e. two-body problem), we can get theanalytical solution; when N≥3, there is no analytical solution. Because of the N-body problem ismuch more complicated than the two-body problem, it is necessary to study the transfer trajectoryfrom the Moon orbit to Sun-Earth L2point and look for potential time and fuel optimal trajectory.This paper aims to study of the transfer orbit design and optimization from the Moon orbit toSun-Earth L2point orbit, at the same time of libration point orbit design, transfer orbit midwaycorrection and periodic orbit station keeping. The mainly used mechanical model is planar circularrestricted three-body problem and the real force model established in STK. A patched doublethree-body method for designing transfer trajectory from low Moon orbit to Sun-Earth L2point isproposed in this paper. The four-body trajectory is divided into two sections of three-body trajectory,the Jacobi constant is used to determine the least energy for a spacecraft to leave the Earth-Moonsystem while the invariant manifold is used to design the transfer trajectory from the sphere ofinfluence to Sun-Earth L2point. By patching these two sections, we can construct an optimalreference transfer trajectory from low Moon orbit to Sun-Earth L2point. Numerical simulations havedemonstrated that after the procedure of differential correction, the initial conditions got according tothe patched double three-body method work well in the real force model, which means this methodcan give a good reference trajectory in the missions about Sun, Earth and Moon. |
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