Ram vehicle glow spectrum; Implication of NO₂ recombination continuum

An experiment was operated on several space shuttle missions to provide spatial and spectral distributions of a ram glow associated with the orbiter. The most recent data featured resolved spectrum and imagery of the glow with spectroscopic resolution of 34 Å FWHM between 4000 and 8000 Å. The spectrum of the glow on the shuttle tail pod could be clearly separated from spectrum of the reflected light from the orbiter. Analysis and comparison have been performed which strongly suggest the emission originates from recombination continuum of NO 2 . Both fast recombination (high temperature) and the spectral dependence in lifetime can describe the spectral difference. If the recombined NO 2 retains 25% of the kinetic energy of the ram OI, the thickness of the glow layer can be explained by the lifetime of NO 2 (²B 1 ) recombination emission.