UPPER LIMITS ON SPACECRAFT-INDUCED ULTRAVIOLET EMISSIONS FROM THE SPACE-SHUTTLE (STS-61C)

Ultraviolet spacecraft-induced emissions from low Earth-orbiting satellites have been reported by several investigators. Several R/angstrom of ultraviolet emission were observed from the S3-4 satellite at altitudes between 180 and 250 km and from the Spacelab 1 shuttle mission at an altitude of 250 km. Conway et al. (1987) showed that N2 Lyman-Birge-Hopfield (LBH) emissions observed by S3-4 at night are probably the result of spacecraft interaction with the atmosphere. We have searched for band emission of N2, OH, O2, and NO in nightglow spectra obtained in January 1986 with the Johns Hopkins ultraviolet background experiment (UVX) flown on the space shuttle Columbia (STS-61C) at an altitude of 330 km. The experimental consisted of two Ebert monochromators spanning the spectral range from 1200 to 1700 angstrom at 17 angstrom resolution and from 1600 to 3200 angstrom at 29 angstrom resolution. The spectra yield 3(sigma) upper limits for the following total band emission rates: NO delta, 0.6 R; NO gamma, 0.7 R; NO beta, 3.5 R; O2 Herzberg I, 4.5 R; OH (A2SIGMA(u)l - X2(PI))(070) and (1,0), 0.1 R, and N2 LBH, 5.3 R. The upper limits for the N2 LBH emissions are consistent with the recent models of spacecraft induced LBH glow of Kofsky (1988), Swenson and Meyerott (1988), and Cuthbertson and Langer (1989) and with a [N2]3 or [N2]2[O] altitude dependence.