Stagnation-point heat transfer rates for Pioneer-Venus Probes

The convective and radiative heat transfer rates are calculated for the stagnation region of the Pioneer-Venus Probe vehicles during their entry nights into the planet Venus. The nonequilibrium thermochemical state of the flow is calculated using a viscous shock-layer method accounting for oxidation of the heat shield surface by atomic oxygen and for pyrolysis-gas injection. Radiative transport along the stagnation streamline is calculated using a line-by-line technique and tangent-slab approximation. For both radiative and convective heating rates, the present results are substantially smaller than the earlier values obtained assuming equilibrium.