Study On The Dynamics Of Mars Entry And Decent Trajectories

Mars exploration has become more and more popular in the field of deep space exploration in recent years.The dynamic problems in entry,descent and landing(EDL)phases during Mars landing mission are the difficulties.Taking China’s further Mars landing exploration plan as the background,this paper analyzes and studies on the dynamics of Mars entry and decent trajectory and many other issues during the EDL process in depth.The details are as follows:1)Aiming at the trajectory optimization problem of the Mars entry phase and considering the constraints of states and paths,an adaptive Gaussian pseudo-spectral method is used to obtain the optimal trajectory with the terminal height and flight path angle as the performance indexes.Besides,the influences of the trajectory length and bank angle constraints on the entry trajectory are discussed.2)Considering the uncertainties of Mars atmosphere,the numerical predictor-corrector method and drag-based tracking method are adopted respectively to solve the Mars entry guidance and control problem.The stability and precision of the guidance law are analyzed by Monte Carlo simulation.At the same time,the nonlinear predictive control method is adopted to reduce peak heat flux and peak overload.3)In order to solve the parachute expansion problem in the Mars descent phase,the dynamic models of the 6-DOF parachute and explorer are established,the uncertainty of the environment is analyzed and the influences of peak force and torque during the parachute expansion on parachute and explorer dynamic properties are studied.Besides,the total attack angle of explorer is constrained by damping control method,improving the stability of parachute expansion.4)In order to solve the heat shield separation problem during the Mars descent phase,the 3-DOF and 6-DOF heat shield separation models are established respectively.The dynamic process of the heat shield separation is simulated and analyzed and the safety is evaluated.The safety analysis method of heat shield separation under different mass and different drag coefficient of the parachute is given.