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

Abstract

Ultraviolet spacecraft‐induced emissions from low Earth‐orbiting satellites have been reported by several investigators. Several R/Å 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 experiment consisted of two Ebert monochromators spanning the spectral range from 1200 to 1700 Å at 17 Å resolution and from 1600 to 3200 Å at 29 Å resolution. The spectra yield 3σ upper limits for the following total band emission rates: NO δ, 0.6 R; NO γ, 0.7 R; NO β, 3.5 R; O2 Herzberg I, 4.5 R; OH (A ²Σu+ ‐ X²Π) (0,0) 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.

Observations of the far ultraviolet airglow by the Ultraviolet Limb Imaging Experiment on STS‐39

“…This results partly from the large uncertainty in the ram-viewing spectrum due to the small LB H signal: the total LBH emission detected in the ram dayglow spectrum is 78+41 R. Assuming the vehicle glow vibrational distribution given by Conway et al [1987], we detect no LBH vehicle glow in the ram-viewing dayglow spectrum and obtain a 3-0 upper limit to the vehicle glow of 41 R at an altitude of 268 km. Furthermore, in a spectrum summed from 682 nightglow scans in a variety of viewing geometries (compiled to characterize the instrumental line shape) no LBH emission is detected, and we set a 3-0 upper limit to LBH emission of 8.5 R. These UVLIM upper limits to LBH vehicle glow brightnesses are consistent with the Conway et al predictions for a 268 km altitude orbit, recent solar maximum FUV photomerry aboard STS-45 [Lampton et al, 1993], and results from the UVX experiment [Morrison et al, 1992], and are much lower than earlier observations from Spacelab 1 at comparable altitudes [Torr et al, 1985].…”

Time variations in the UV background

“…We know that airglow does vary over the course of an observation but Murthy (2014b) have shown that there is little airglow contribution within two hours of orbital midnight. The primary emission lines in the GALEX bands are the geocoronal O I lines at 1304 and 1356 Å in the FUV and at 2471 Å in the NUV (Morrison et al 1992;Feldman et al 1992) with Kulkarni (2021) suggesting that continuum two-photon emission from the atmosphere could contribute about 20 photon units to the background but all these mechanisms would contribute more to the FUV emission than the NUV, which is not what we see.…”

The 1997 reference of diffuse night sky brightness

“…These observations at 250 km altitude were performed under conditions of moderate solar activity. During minimum solar activity and at 330 km, Morrison et al (1992) observed no such emissions. The GAUSS camera onboard the German Spacelab mission D2 (296 km, moderate solar activity) observed a patchy glow with ≈ 0 − 3 10…”

“…shows an appropriately scaled solar spectrum and is assumed to show the contribution to zodiacal light. From Morrison et al (1992) thus enabling a "thumb-cinema" look at these spatiotemporal variations. Quantitative examples for variation during one night or variation with solar cycle can be seen in Figs.…”