The present paper discusses the development of a margin policy for radiative heating during lunar return Earth re-entry. The approach starts with stagnation line radiance predictions, for which significant validation data are available, and follows a mathematical formalism to translate the uncertainty in radiance prediction to an uncertainty in radiative heating. The analysis accounts for uncertainties in equilibrium and non-equilibrium radiance, angular integration, boundary layer absorption, and flowfield-radiation coupling. Uncertainties based on parametric analyses are then reduced through Bayesian inference against experimental data. Terms are introduced to account for the neglect of ablation products and trace air species. The impact is then assessed through analysis of candidate entry trajectories. The major contributors to margin are uncertainty in equilibrium radiation parameters, non-equilibrium radiation and neglect of trace species.
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