The Computation Of Reentry Ballistic Trajectory For Space Debris And Ground Hazard Analysis

The main purpose of the present work is to establish a complete methodology for space debris reentry ballistic trajectory computation and ground hazard analysis,in which the choice of coordinate systems,the deduction of reentry ballistic equations,the modeling of debris,computer program coding and case analysis for ground hazard,are all included.There are two models of debris discussed in this work: solid sphere debris model and flat-plate debris model.The first one is very simple in aerodynamic analysis,and the second one involves complicated aerodynamic consideration and is close to real condition.In solid sphere debris model,debris of variable shape is regard as a solid sphere with the same mass and material type.In this case,aerodynamic lift need not be considered,and the aerodynamic ablation effects can be calculated based on average heat flux.According the different distribution type of internal temperature for solid sphere,two kinds of ablation model,i.e.zero and one dimensional model,are introduced and analyzed.In flat-plate debris model,the movement of debris is simplified,and the aerothermal effects are neglected.Based on the principles of dynamics for dilute gas and continuum gas,the calculation method for aerodynamic lift and drag of flat-plate debris is discussed,and is embedded into the solution of reentry equations.A computer program is built in present work,which can compute space debris reentry ballistic trajectories based on different debris model described,and the results are compared.Finally,considering geography information and population distribution data,the ground hazard induced by space debris reentry is assessed.