Features of Afterbody Radiative Heating for Earth Entry

Abstract

Radiative heating is identified as a major contributor to afterbody heating for Earth entry capsules at velocities above 10 km/s. Because of rate-limited electron–ion recombination processes, many of the electronically excited N and O atoms produced in the high-temperature/pressure forebody remain as they expand into the afterbody region, which results in significant afterbody radiation. Large radiative heating sensitivities to electron-impact ionization rates and escape factors are identified. Ablation products from a forebody ablator are shown to increase the afterbody radiation by nearly 40%, due to the influence of CO on the vibrational-electronic temperature. The tangent-slab radiation transport approach is shown to overpredict the radiative flux by as much as 50% in the afterbody, therefore making the more computationally expensive ray-tracing approach necessary for accurate radiative flux predictions. For the Stardust entry, the afterbody radiation is predicted to be nearly twice as large as the c...