Nonequilibrium radiative heating during outer planet atmospheric entry

The contradictory results obtained by investigators assessing the influence of finite-rate ionization on the radiative heating of probes entering the atmospheres of Jupiter and Saturn are discussed. Tiwari and Szema (1979) found that the radiation heating increased, whereas Leibowitz (1973) and Liebowitz and Kuo (1976) found that it decreased in relation to the results obtained when the ionization rate was assumed to be in equilibrium at the local thermodynamic conditions. The study presented here is limited to stagnation shock layers for nonviscous, hydrogen-helium plasmas with cold, nonblowing conditions at the probe heat shield. It is found that the radiative heating comes mainly from the Balmer region of the spectrum, where the shock layer is optically thin.