Shock Radiation Measurements for Mars Aerocapture Radiative Heating Analysis

NASA's In-Space Propulsion Technology program is supporting the development of shock radiation transport models for aerocapture missions to Mars and Venus. Phenomenological models of nonequilibrium shock radiation will be incorporated into high-fidelity flowfield computations used to predict the aerothermal environments for a Mars or Venus aerocapture entry vehicle. These models are validated with shock radiance measurements obtained at flight-relevant conditions. A comprehensive test series in the NASA Ames Electric Arc Shock Tube facility at a representative freestream condition was recently completed. The facility's optical instrumentation enabled spectral measurements of shocked gas radiation from the vacuum ultraviolet to the near infrared. The instrumentation captured the nonequilibrium postshock excitation and relaxation dynamics of dispersed spectral features. A description of the shock tube facility, optical instrumentation, and examples of the test data are presented.