Spectral measurement of the Space Shuttle leeside shock layer and wake

Leeside shock layer and wake spectral radiation measured during the high altitude portion of the reentry of Space Shuttle Orbiter STS 51-D are presented and are compared with similar measurements obtained in an arc jet tunnel. The spectra, measured with a low-resolution spectral camera, are compared in order to identify the radiating species in a wavelength range from 4000 to 8000 angstroms. Emissions identified are: N2 first positive and N2 second positive systems, the N2(+) first negative system, and the sodium-D lines. No atomic air species or CN are observed. The spectra and procedure will be of use in comparison of flight flowfield properties with computational predictions and for guidance in developing future flight experiments.