814 ISSN 1990-7931, Russian Journal of Physical Chemistry B, 2008, Vol. 2, No. 5, pp. 814–826. © Pleiades Publishing, Ltd., 2008. Original Russian Text © S.T. Surzhikov, 2008, published in Khimicheskaya Fizika, 2008, Vol. 27, No. 10, pp. 63–76. INTRODUCTION In several projects for studying the Moon and solar system planets with the use of automated (piloted in the future) space vehicles, expedition scenarios are devel- oped in which radiation heating of the surface of a space vehicle entering dense atmospheric layers of planets and the Earth becomes commensurate with con- vective heating. A component of these projects is the development of computer models and codes for the expert examination of aerothermodynamic characteris- tics in various scenarios of entering dense atmospheric layers. The history of the astrophysics of descent space modules counts more than forty years of intense stud- ies. However, several fundamentally important prob- lems in this area cannot be considered solved at present, especially when it is necessary to analyze the aerother- modynamics of space vehicles during superorbital approach, when not only dissociation but also gas ion- ization in the shock layer becomes very important. Among the most urgent problems of increased interest to specialists from aerospace community, we can men- tion (1) the physicochemical kinetics of high-tempera- ture dissociated and ionized gases, (2) the properties of transfer of partially ionized gases under nonequilibrium conditions, (3) the spectral optical properties of par- tially dissociated and ionized gases, (4) the numerical algorithms for calculating flows of viscous, heat con- ducting, radiating, and physically and chemically non- equilibrium gases in two- and three-dimensional vol- umes with complex geometry, and (5) models of the physical and chemical kinetics of interaction of ionized gas flows and radiation with the thermal protection material of space vehicles (including the thermal destruction of thermal protection materials). Testing and certifying computer codes, first of all for the example of an analysis of the results of Earth tests and flight experiments, is likely the most important problem of modern aerophysics. Practice of world aerophysical studies includes only several flight exper- iments in which the densities of convective and radia- tion thermal fluxes on the surface of a space vehicle entering dense atmospheric layers were measured. The flight data of the Fire-II space experiment [1, 2] are most well documented at present. For this reason, these experimental data are extensively used for estimating the correctness of computer codes. In this flight experiment, the density of the total (convective and radiation) heat flux to the surface of the descent module of a segment-conical shape was mea- sured along the trajectory at the initial rate of entry V ∞ = 11.4 km/s. The flight data of the Fire-II project have two funda- mentally important special features. Part of measure- ments were performed under strongly nonequilibrium conditions in a shock layer, and part of measurements, under the conditions well described by the local ther- modynamic equilibrium model. Up to now, many attempts at calculation-theoretical interpretation of the Fire-II flight data resulted in substantial discrepancies between the calculation results and experimental data [2]. The differences between the calculation results HEAT AND MASS TRANSFER IN CHEMICAL KINETICS A Study of the Influence of Kinetic Models on Calculations of the Radiation-Convective Heating of a Space Vehicle in Fire-II Flight Experiment 1 S. T. Surzhikov Institute for Problems of Mechanics, Russian Academy of Sciences, pr. Vernadskogo 101, Moscow, 117526 Russia e-mail: Surg@ipmnet.ru Received March 15, 2007 Abstract—The aerodynamics of descent modules that enter dense atmospheric layers at a superobital velocity is studied using the Non-Equilibrium Radiation Aero Thermodynamics (NERAT) code and several models of the chemical kinetics of partially ionized air. The conditions of the Fire-II flight experiment are considered. It is shown that the Park, Dunn–Kang, and Martin–Bortner models extensively used in aerophysics provide satis- factory agreement between the calculated convective flux densities and those measured in the flight experiment. These models, however, predict different temperature levels in the shock layer, which can be of importance for correct calculations of radiation heat flux densities. DOI: 10.1134/S1990793108050254 1 Presented at the XXXI Academic Readings on Astronautics, Mos- cow, January 2007.