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A numerical tool is developed for the design and analysis of Mars atmospheric entry trajectories. Simple latitude dependent density model is employed along with an approximate temperature model for Mars' atmosphere. Radiative heat flux and convective heat flux (with cold wall boundary condition) relations are used for the study of stagnation point...
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... inclination of its axis of rotation (similar to the terrestrial) and the high eccentricity of the Martian orbit induce a seasonal cycle more intense than the terrestrial one. However, neglecting these seasonal variations, a typical temperature profile is used (Figure 1). The calculation of convective heat fluxes is carried out using the Sutton-Graves convective heating correlation [4]. ...
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Citations
... are longitude, latitude, flight-path angles, heading angles, and bank angles [14]. The variables D L, are the lift acceleration and drag acceleration. ...
... Correspondingly, this study selected the terminal altitude as the optimization goal and performance index to maximize terminal altitude. As shown in equation (10) (14) Therefore, 3240 groups of simulations were conducted with combinations of different Mars entry scenarios, vehicular parameters, and process constraints. A total of more than 1400 groups of optimal solutions were obtained. ...
Trajectory optimization technology used for Mars entry is one of the key technologies for planetary exploration. Evaluation of the performance of the entry trajectory under conditions of complex atmospheric dynamics, various vehicular design parameters, and multiple constraints in the process of entry, are important issues pertaining to the design of trajectories. In this study, an efficient evaluation approach of the terminal state for Mars entry is proposed based on Gaussian process regression to evaluate the maximum terminal altitude for different entry velocities, terminal Mach numbers, and vehicular parameters. Additionally, the influences of entry flight-path angle, lift-drag ratio, and ballistic coefficient, on the maximum terminal altitude are analyzed. A genetic algorithm is used in the optimization solver to avoid local minima and to guarantee the data quality of the training samples used for Gaussian process regression. The mean function, kernel function, and hyperparameters are selected as the optimization parameters for Gaussian process regression to describe the correlation between samples, and the maximum terminal altitude prediction model is then established. Numerical simulations demonstrate that the proposed method can achieve the evaluation of more than 3000 group scenarios within tens of seconds with a mean relative error that is less than 4%.
... Ping Lu [5] uses truncated dynamics to generate the optimal profiles of the aerodynamic angles. In this paper, for the dynamics of the entry mission, 3 DoF state equations with respect to spherical non-rotating Mars are used [6]. A quadratic polynomial as a function of angle of attack is derived to represent the variation of aerodynamic coefficients. ...
The optimal profiles of angle of attack and bank angle of a Mars entry vehicle to achieve the target site starting from certain entry conditions are obtained. The problem is formulated as a two point boundary value problem using an indirect approach based on Pontryagin’s principle of optimal control theory. The solution is obtained using differential evolution technique, an heuristic optimization technique. To handle the ‘angle of attack’ in the indirect approach, a quadratic polynomial is used to represent aerodynamic coefficients as a function of angle of attack.
... The equations of motion of a nonthrusting entry module of mass m with respect to nonspherical rotating Mars are [4,11] ...
