The Space Shuttle's far ultraviolet environment

Abstract

The recent discovery of the glow phenomena have triggered a renewed interest in the study of the optical environment near shuttle altitudes. Two astronomy experiments on Spacelab I, the Far Ultraviolet Space Telescope (FAUST) and the Very Wide Field camera (XWC), have experienced considerable contamination in the far ultraviolet (FW) wavelength region. The most likely cause for these emissions is the tropical ultraviolet emission which in turn is the result of radiative recombination of o+ ions. The Imaging Spectrometric Observatory (ISO) experiment on the Spacelab I which covered the same wavelength range at the same time did not observe the tropical ultraviolet emissions. A spectrometer on the S3-4 satellite observed a bright N, LBH signal (-- 1 kR) which mas subsequently confirmed by the IS0 experiment. However, several other rocket and satellite experiments which had the capabilities to observe LBH emissions did not observe them. Previous to the IS0 observations, the LBH emissions were observed to originate only in the summer northern hemisphere. The IS0 observed them in both hemispheres. In this paper, we examine these and other observations and point out the evidence for substantial intensity variations in the far ultraviolet at shuttle altitudes. Further investigation using several instruments is essential for a complete understanding of the optical environment of the Space Shuttle.