Abstract: Radiometers and Spectrometers embedded as flight instrumentation in a spacecraft’s thermal protection system (TPS) can generate data on shock layer radiation to a spacecraft’s surface for high-speed trajectories such as lunar return. Robust and accurate flight measurements of shock layer radiation can validate models and inform TPS selection and sizing, to reduce risk and TPS launch mass. Contamination from soot deposition and ablation products in the boundary layer condensing on a cold sapph…