A STUDY OF THE IMPACT OF THE SPACE-SHUTTLE ENVIRONMENT ON FAINT FAR-UV GEOPHYSICAL AND ASTRONOMICAL PHENOMENA

FAUST is a far ultraviolet (1400-1800 angstrom) photon-counting imaging telescope featuring a wide field of view (7.6-degrees) and a high sensitivity to extended emission features. During its flight as part of the ATLAS-1 payload aboard the STS-45 mission in March 1992, nineteen deep-space nighttime viewing opportunities were utilized by FAUST. Here we report the observed fluxes and their time and space variations, and identify the signatures of post-sunset airglow phenomena and Orbiter vernier attitude-control thruster firing events. We find that the Space Shuttle nighttime environment at 296 km altitude is often sufficiently dark to permit geophysical and astronomical UV observations down to levels on the order of 1000 photons/cm2 sr angstrom s, i.e., 0.01 Rayleighs/angstrom. We also find evidence for occasional geophysical fluxes of some tens or hundreds of Rayleighs in the upward-looking direction.