High-Resolution Spectroscopy of the Hayabusa Reentry Using a Fabry-Perot Interferometer

Spectroscopic observations of the Hayabusa reentry are presented as obtained by an instrument combining Fabry-Perot interferometry and classical optical emission spectroscopy. The instrument was deployed onboard NASA's DC-8 airborne laboratory as part of the Hayabusa Reentry Airborne Observation Campaign led by NASA, in close collaboration with Japan Aerospace Exploration Agency. The covered wavelength range in the low-resolution mode is from 738.4to 852.1nm with the aim to acquire simultaneously the neutral atomic oxygen triplets at 777 and 844nm and the nitrogen lines at 746 and 821nm. The high-resolution mode reaches a wavelength resolution of =0.01nm. The intention of this instrument was to measure the translational temperature of the neutral atoms in the plasma flow ahead of the Hayabusa capsule. Air plasma emissions were detected at high resolution, but not at high enough signal to noise to measure the linewidth with sufficient accuracy. As expected, the measurements demonstrate the absence of significant pressure broadening in the lines compared with plasma wind-tunnel conditions.