Absolute Radiation Measurement in Venus and Mars Entry Conditions

摘要

Comparisons of experimental characterization and model predictions of entry radiation relevant to Mars and Venus exploration are presented. Characterization is performed in the recently upgraded Electric Arc Shock Tube facility at NASA Ames Research Center. Tests are performed in simulated Mars (96% CO_2, 4% N_2) and Venus (96.5% CO_2, 3.5% N_2) atmospheres at downstream pressures and incident velocities spanning from 0.1 to 2.0 torr and 3-12 km/s. Velocity and pressure conditions were chosen based on expected flight conditions (direct entry or aerocapture) for Mars and Venus atmospheres. The absolute radiance data are spatially and spectrally resolved and span the vacuum ultraviolet through midinfrared (120-1650 nm, 3-5 μm). Resolved spectra of the CO fourth positive band in the vacuum ultraviolet are reported for the first time. Measurements of CO_2 molecular vibrational radiation are also attempted at low-velocity conditions. Radiation modeled using an equilibrium assumption with the NEQAIR code compares favorably to measured radiation under some, but not all, conditions.