Development of a Radiative Heating Margin Policy for Lunar Return Missions

Abstract

The present paper discusses the development of a margin policy for radiative heating during lunar return Earth reentry. 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 nonequilibrium 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, nonequilibrium radiation, and neglect of trace species.