Examination of Radio Frequency Blackout for an Inflatable Vehicle During Atmospheric Reentry

Abstract

Numerical simulations of the plasma flow and electromagnetic wave around a membrane-aeroshell type reentry vehicle were performed using various physical model combinations, and the possibility of radio frequency blackout of transceiver antenna embedded at the rear of the vehicle was investigated. The flowfield was assumed to be in thermochemical nonequilibrium, and it was described by the Navier–Stokes equations with a multitemperature model and the equation of state. The simulations were performed for several altitudes, including the highest heat flux point according to reentry orbit data. Through these computations, the detailed distributions of the flowfield properties in the shock layer and wake region were successfully obtained. To evaluate the possibility of radio frequency blackout during atmospheric reentry, the distribution of the electron number density around the inflatable vehicle was clarified. A frequency-dependent finite-difference time-domain method was used for simulations of electromagnetic waves, and the physical properties were obtained from the computational results of the plasma flow calculation. Electromagnetic wave behaviors in an ionized gas region behind the inflatable vehicle were investigated. It was found that the number density of electrons was sufficiently small and that the electromagnetic waves can propagate with no reflection and less attenuation. These results suggest that radio frequency blackout may not occur during the atmospheric reentry of the inflatable vehicle.