A surface chemistry model for the altitude dependence of the N₂ Lyman‐Birge‐Hopfield glow on spacecraft

Abstract

Low‐orbiting spacecraft have been observed to cause UV emission in the N2 Lyman‐Birge‐Hopfield bands. We examine the chemical processes expected to underlie this emission. Recombination between incident and adsorbed N atoms has been proposed as the source of radiating N2*; however, the cubic dependence of the intensity, as [N2]³ or [N2]²[O], has not been explained. We suggest that this can be explained by a model where adsorption of nitrogen on the spacecraft surface is balanced mainly by the removal of N from the surface by atomic oxygen. On the basis of these assumptions we construct a mathematical model for the production of N2*. We show that for large enough reaction efficiencies our model predicts a magnitude and altitude dependence for the emission which can explain the measurements reported by other investigators.

Upper limits on spacecraft‐induced ultraviolet emissions from the space shuttle (STS‐61C)

“…Similar emission, also at a level of several R/•, has also been observed in spectra from the space shuttle Spacelab 1 experiment [Torr et al, 1985] from an altitude of 250 km. Various mechanisms have been proposed to explain the induced N 2 LBH glow [Kofsky, 1988;Swenson and Meyerott, 1988;Cuthbertson and Langer, 1989] that are consistent with a [N2] 3 or [N21210] altitude dependence.…”

Optical Aeronomy

“…LBH bands are conspicuous features in vehicle glow, [e.g., Conway et al 1987]. There has been considerable interest in understanding this particular emission, with surface chemistry models advanced by Kofsky [1988], Swenson and Myerott [1988], Myerott and Swenson [1990], and Cuthbertson and Langer [1989]. For other work of interest on modeling of spacecraft‐atmosphere interactions see Gordon and Seebaugh [1989], Elgin et al [1990 a,b ].…”