Viscous shock layer analysis of the Martian aerothermal environment

Detailed surface heating and flowfield results have been obtained for the stagnation region of a planetary exploration vehicle entering the Martian atmosphere. A viscous shock layer analysis (which includes an absorbing boundary layer) is used to obtain solutions with and without coupled ablation injection. Recently developed curve fits for the transport and thermodynamic properties of Martian atmospheric and ablation species as well as for the absorption coefficient for CO(4+) are employee. Extensive results are provided at altitudes of 30, 36, and 50 km for bodies with nose radii of 1, 2.3, and 23 m at freestream velocities of 6, 8, 10, and 12 km/s. Sublimation temperature is employed with coupled ablation injection cases, whereas radiative equilibrium wall temperature is used without injection. Only for bodies with large nose radii (23 m or larger) and for velocities of approximately 6 km/s can a reusable heat shield (with the currently available materials) be used. For higher velocities or vehicles with smaller nose radii, an ablative thermal protection system will be required. A comparison with thermochemical nonequilibrium calculations suggests that much of the flow in the shock layer is in thermochemical equilibrium for the cases analyzed. This is one of the first studies for the Martian entry conditions of large size bodies with coupled radiation and ablation injection.