COLLISIONAL DESORPTION OF NO BY FAST O ATOMS

Surface-adsorbed NO figures largely in the mechanism that produces vis ible glow around spacecraft in low Earth orbit (LEO). In view of the p otential interference to optical observations such a glow represents, we have investigated the collision-induced desorption of NO from Al, N i, and Z306 Chemglaze(R)-coated surfaces at 96 K by hyperthermal (8 km /s) oxygen atoms. The removal of surface NO was followed by the monito ring of the visible fluorescence of electronically excited NO2. produc ed through the surface-mediated reaction O+NO. A variability in collis ional desorption rate with material was observed. The limited data sug gest a removal efficiency of 4 to 8% of the impinging O atom flux. Imp lications for the atmospheric scouring of contaminants from external s urfaces of LEO spacecraft are discussed.