A Research Of Orbit And Attitude Of Spacecraft

The libration points of the restricted three-body problem is very important in space exploration.The libration points can be the ideal region for observing celestial bodies in space and also can be used as a staging region for interplanetary space exploration missions.Scholars have done a lot of work on the design of transfer trajectory to reach these libration points and periodic orbit around them.Same with the orbit motion,the attitude motion of the spacecraft is also very important.Based on the above background,this paper studies related dynamics problems involved in space missions.The main research contents and innovations of this paper are as follows:Analytical solutions of periodic configurations around an arbitrary equilibrium point are constructed.The periodic motions are expanded as formal series of in-plane and out-of-plane amplitudes,then the 15-order solutions are obtained by taking Lindstedt-Poincare(L-P)method.According to the method of polynomial expansions,a pair of modal coordinates is chosen,and the remaining state variables are expressed as poly-nomial series about the modal coordinates,then the 8-order solutions are constructed.Considering the fact that relative motion model is a special case of the restricted three-body problem,the periodic configurations constructed in the model of relative motion are taken as starting solutions to numerically identify the periodic orbits in restricted three-body problem by means of continuation technique with the mass of system as continuation parameter.The low-energy transfer trajectories of a spacecraft from the Earth to periodic or-bits around Sun-Earth libration point L2(SE-L2)are constructed.Initially,We studied Earth-Moon transfer trajectories in the circular restricted three-body problem(CRTBP)from the viewpoint of families,and twelve families of trajectories with transfer time shorter than fifty days are identified.By connecting these transfers with stable man-ifolds of the target orbit,low-energy transfers from the low Earth orbit to a small-amplitude periodic orbit around SE-L2 are determined in two separate CRTBPs(Earth-Moon and Sun-Earth CRTBPs).Then,taking the patched trajectories as initial guesses and introducing a small maneuver at the perilune,we optimize the whole transfer tra-jectories in the Sun-Earth-Moon-Spacecraft system.Results indicate that it is possible to realize low-energy transfers to small-amplitude orbits around SE-L2 by patching the Earth-Moon transfers with stable manifolds of the target orbits.The attitude motion of a rigid spacecraft is studied in the Earth-Moon CRTBP.Firstly,the equilibrium attitude and its stability as functions of the moments of inertia are discussed when the spacecraft is assumed at the libration points.Then,periodic attitude motions of a spacecraft with mass distribution given in the stable regions are obtained.Regarding space mission applications,the Sun orientation is discussed and the orbit-attitude resonances are constructed for spacecrafts working on the libration point orbits by means of a continuation procedure.