Analysis of STS-39 Space Shuttle glow measurements

Measurements of Space Shuttle glow were conducted on STS-39. Cargo-bay infrared and visible sensors measured intensities and spectral distributions of shuttle glow as a function of attitude, gas releases, day/night, and mission elapsed time. One of these sensors, the Spacecraft Kinetic Infrared Test (SKIRT), was a cryogenic infrared spectrometer which observed nitric oxide, ionized nitric oxide, and hydroxyl in the quiescent and thruster-enhanced Shuttle glow. A nitric oxide gas release significantly enhanced the glow and showed a fast gas-phase reaction and a slower surface-mediated reaction. The glow was also shown to be dependent on the orientation of the Shuttle. The change in glow intensity from pointing the orbiter and sensor along the velocity vector, into ram, versus looking 90 deg from ram, showed a cos-squared Theta dependence. During nonglow quiescent times, when SKIRT was pointed away from ram toward deep space, there were no emissions down to the sensor noise level of 10 exp -10 W/sq cm sr micron. (Author)