REENTRY flows are characterized by high-temperature effects, like internal energy excitation, chemical reactions, and ioniza- tion. The thermochemical processes and their nonequilibrium effects determine the temperature of the gas that envelops the vehicle. They also alter the gas composition and associated properties, like conductivity and viscosity of the gas mixture. These have a dominant effect on the shock standoff distance, surface heat flux, and other aerothermodynamic characteristics of the vehicle.