SPATIAL AND SPECTRAL CHARACTERIZATION OF LABORATORY SHUTTLE GLOW SIMULATIONS

Laboratory experiments designed to uncover mechanistic information about the spectral and spatial characteristics of shuttle glow were conducted. Pulsed oxygen atoms traveling at orbital velocities were directed toward a substrate which was previously dosed with NO molecules. Heterogeneous recombination of the O and NO species resulted in NO2* exiting the surface of the sample, and an associated emission was found to extend from the sample plane. In the experiments the materials investigated were Z306 Chemglaze(R) (a common baffle black paint), aluminum, and nickel. The sample temperatures were varied from 300 to 77 K, and the oxygen atom velocity was varied from 5 to 10 km s-1. The experimental results include the measure of (1) an effective NO2* lifetime of 185-mu-s, (2) complete surface thermal accommodation of the formed NO2*, (3) a large NO2* emission brightness which was inversely related to surface temperature, and (4) a spectral shape which indicates a red shifting to distance from the sample as well as (5) a slight spectral shift which appears to be material related. The preliminary experimental data from this experiment were presented by Caledonia et al. (1990).