Absolute Radiation Measurements Behind Strong Shock Wave In Carbon Dioxide Flow for Mars Aerocapture Missions

Abstract

Absolute radiation measurements behind strong shock wave in Mars simulant gas composed of 96% CO2 and 4% N2 are conducted in a shock tube developed in JAXA Chofu Space Center in order to expect the radiative heating for future Mars aerocapture missions. Emission intensities from VUV to NIR region are obtained at 133.3Pa, 7.0km/s and 13.3Pa, 8.5km/s. The absolute spectral radiances from VUV to UV region are calibrated with a Deuterium lamp. On the other hand, the absolute spectral radiances from UV to NIR region are calibrated with a tungsten halogen lamp. By setting both of these lamps at the measurement positions, spectral radiance from VUV to NIR region can be obtained. At 133.3Pa, 7km/s, the flow is achieved in thermal equilibrium around 5mm behind the shock wave front, while at 13.3Pa, 8.5km/s, the flow is totally in nonequilibrium. The simulated profiles from 300 to 650nm in equilibrium estimated with CFD and radiation analysis code, SPRADIAN2, have a good agreement with the experimental results.