State-to-State Modeling of CO for Mars Entry Applications

Abstract

This work addresses the study of the dynamics of the excited states of CO in shock heated Mars’s atmosphere. The model accounts for thermal non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. Furthermore, electronic states of molecules are treated as separate species, allowing for non-Boltzmann distributions of their populations. Two approaches have been considered and compared: i) state-to-state and ii) quasi-steady state. Both strategies are applied to the modeling of the flow behind a normal shock wave, for Mars entry conditions. The results indicate that the use of a quasi-steady state approach can lead to a substantial dissociation of the excited CO molecules, thus leading to a drastic underestimation of the radiation heat flux.