Ionizational Nonequilibrium Heating During Outer Planetary Entries

Abstract

An analytical tool has been developed which enables the impact of ionizational nonequilibrium effects on outer planet entry heating to be estimated. The analysis combines recent shock-tube experiments, flowfield calculations, and planetary entry trajectory analysis. The thickness of the nonequilibrium layer and its variation around the entry body have been correlated by a reaction flow parameter over a wide range of entry conditions. The influence of nonequilibrium effects on heating during entry into Saturn and Jupiter model atmospheres has been studied and the effect of vehicle size and ballistic coefficient determined. An ionizational nonequilibrium layer of significant thickness was found to exist during portions of entry into Saturn and Jupiter warm atmospheres. However, the nonequilibrium layer was found to be thin during the peak heating portions of the trajectory and resulted in reductions in total probe heating of less than 15%.