Sensitivity of Dragonfly Afterbody Radiation to Chemical Kinetic Parameters and Freestream Methane

Dragonfly is a NASA mission that aims to deliver a rotorcraft to explore the near-surface environment of Saturn's moon Titan. The flow around the Dragonfly capsule entering the Titan atmosphere is simulated and used to determine the associated radiation. The goal of the analysis is to determine whether the freestream concentration of methane in the Titan atmosphere can be reliably inferred from backshell radiation instrumentation that will be installed on the Dragonfly capsule. Chemical kinetic parameters are varied to understand their contribution to radiative heat flux uncertainty. Bayesian uncertainty quantification is applied to inversely model freestream methane concentration at individual points of the Dragonfly trajectory. The results show that the level of free stream methane impacts the radiation from the CN red system more than from CN violet. Therefore, the ratio of these bands can potentially be used to determine freestream methane concentration during post-flight reconstruction while sidestepping potential uncertainty from boundary layer processes.