Analysis of air radiation measurements obtained in the EAST shocktube facility

The Vision for Space Exploration has renewed interest in understanding the radiation that is encountered during re-entry into Earth’s atmosphere. In particular, the focus has been to consider conditions that are relevant to the Orion capsule, as part of the Crew Exploration Vehicle (CEV) Aerosciences Project (CAP). Because the radiation is a significant portion of the heat flux, although only for a relatively short time in the trajectory, detailed simulations and experiments have been undertaken to quantify this radiation and the associated uncertainties (Johnston 2008; Bose et al. 2008; Panesi et al. 2009). Previous studies have identified significant differences between the experimental measurements taken in the Electric Arc Shock Tube (EAST) facility at the NASA Ames Research Center (Cruden et al. 2009) and theoretical models (Bose et al. 2008), such as NEQAIR (Whiting et al. 1996)) and HARA (Johnston 2006). Understanding these uncertainties are therefore critical in the design of the thermal protection system (TPS). The present analysis should help provide an insight into the level of fidelity of the theoretical models, and to any previous discrepancies that have already been identified, such as the level of the background continuum (Bose et al. 2008).