Nonequilibrium Chemistry and Radiation for Neptune Entry

Abstract

A theoretical model to describe the thermochemical nonequilibrium and radiation phenomena in the shock layer over a spacecraft entering the planet Neptune is derived by assembling existing information. This model is applied to predict the flow in a constant-area channel behind a normal shock wave in a mixture representing the atmosphere of the planet. Calculation is made for aerocapture flights into Neptune that have been considered in the past. It is shown that the presence of methane in the planet's atmosphere shortens the time for equilibration and typically increases the radiative heat flux by about 50%. Radiative heat flux values are calculated over a range of densities and velocities expected in an aerocapture flight into Neptune.