Prediction of flight measurements of high-enthalpy nonequilibrium flow from a cubesat-class atmospheric probe

Physical chemical aspects of high-enthalpy, non-equilibrium flows affect radiation and heat transfer estimates at low-earth altitudes, which is important for modeling thermal protection systems. For diatomic molecules, high energy collisions in the bow shock region result in rovibrionic transitions and release of photons in different wavelength bands. In this work, the Direct Simulations Monte Carlo (DSMC) method is used for the SASSI² mission to determine the external flow field around the 3U CubeSat and the internal flowfield of custom pressure sensor ports. The Nonequilibrium Radiative Transport and Spectra Program (NEQAIR) code is used to determine ultraviolet radiation from nitric oxide and the tangent slab approximation is used to estimate spacecraft visible glow radiance from nitrogen dioxide. Additional calculations are performed to provide a sensitivity analysis of estimates based on the DSMC code utilized, chemical reaction rates, and CubeSat orientation.