Study On Reentry Trajectory Design And Guidance Approach For Lifting Spacecraft

Reentry into the earth’s atmosphere is a crucial step to the Manned SpaceMission, especially for the spacecraft returning from the moon that encountersextremely severe environment in the entry phase with higher entry velocity. Reentrytrajectory design and guidance approach are researched in this dissertation under thebackground of manned lunar-landing mission, and the main results are summarized asfollows:First, the dynamic model of reentry is established as well as the definitions ofcoordinate systems, the transfer matrices and eulerian angles, based on which adynamic simulation program in FORTRAN is developed.Next, a trajectory design method based on the concept of cruise parameter isstudied. By investigating the relation between trajectory characteristics and kinematic/dynamic parameters, the method concludes a corresponding relationship betweenbank angle and parameters of trajectory. Also, trajectories are generated with themethod under different designing conditions of cruise parameters. Simulation resultsdemonstrate that all the trajectories satisfy the request of designed cruise values.Then, the dissertation makes a research on reentry trajectory characteristics ofthe lunar-landing vehicle, comparing the reentry from moon-earth transfer orbit withthat from low earth orbit (LEO); the relationship between initial velocity and initialpath angle is analyzed as well as the regulation of bank angle’s impact on downrangeand crossrange and the envelope of direct reentry, composed of initial velocity andpath angle, is obtained. In this dissertation, the method based on the concept of cruiseparameter is applied in the reentry trajectory design of lunar-landing spacecraft, wherethe constant-overload trajectory, trajectory of linear-overload with height and a skiptrajectory constrained by constant-overload are achieved; by examining the ability ofquasi-glide flight, the dissertation interprets why the spacecraft cannot maintain arelatively low stagnation heat flux by flying at the height of rarefied atmosphere.Finally, the guidance for spacecraft reentry is studied with focusing on NominalTrajectory-Based guidance and Predictor-Corrector guidance, and the performance ofNominal Trajectory-Based guidance is evaluated.In conclusion, the work involved in this dissertation can be reference in futuremanned lunar mission and the trajectory design method has a promising potential forfurther application.