A series of laboratory measurements have been performed in order to provide a mechanistic interpretation for the visible shuttle glow. These studies involved interactions of an 8 km/s oxygen atom beam with both contaminated dosed surfaces and gaseous targets. We conclude that visible shuttle glow arises from surface mediated O+NO recombination via a Langmuir-Hinshelwood mechanism and that the gas-phase exchange reaction O+N2→NO+N provides a viable source of precursor NO above surfaces oriented in the ram direction. ¿ American Geophysical Union 1993