THE SHUTTLE GLOW PHENOMENON

Spacecraft in low earth orbit exhibit an unusual phenomenon: Surfaces facing the atmospheric wind produce a bright orange glow. This phenomenon was first noticed on the space shuttle but has since been verified as occurring on all spacecraft. The intensity of the glow depends on atmospheric density, on the angle between the velocity vector and the spacecraft surface, and on the temperature of the surface. This review summarizes the observations as well as the current explanation for the glow, namely its being due to NO2* formed in surface-aided recombination between O and NO. Laboratory measurements and surface studies related to the phenomenon are briefly discussed.