Nonequilibrium and Equilibrium Radiation to the Space Tug from the Shock Layer

Preliminary estimates of the thermal radiation heat transfer to an aerobraking space tug are presented. The tug is descending from a geosynchronous orbit to a low earth orbit on one or more passes through the atmosphere. For the flight regime of the tug, between a velocity of 22,000 ft./sec. and 34,000 ft./sec. with an altitude between 220,000 ft. and 340,000 ft., the nonequilibrium radiation can be more than 1,000 times larger than the value of the equilibrium radiation. Therefore, an analysis of the radiative heating for these altitude must include the nonequilibrium radiation from the shock layer.