Previous abstract Next abstract
We present the first far-ultraviolet (FUV) images of the Moon, obtained using the Ultraviolet Imaging Telescope (UIT) during the Astro-2 Spacelab mission in March, 1995. The data set comprises images taken at three phase angles ($3.7^\circ$, $33.8^\circ$, and $57.4^\circ$), through three FUV filters (B6: 130--170~nm, B1: 135--170~nm, and B5: 150--175~nm), for four exposure times each (ranging from 1.3s for the shortest full Moon B1 exposure to 105s for the longest $57.4^\circ$-phase B5 exposure). Although a very difficult target to track (due to the combined $0.5''$/s proper motion of the Moon and the 0--$4''$/s parallax motion from the shuttle), the apparent resolution of the images is $<5''$, or about 10~km on the lunar surface. Since UV emissions from the Moon are due entirely to reflected sunlight, the FUV images will provide useful new data on the ultraviolet scattering properties of lunar soils as a function of phase angle. In addition, these images will be used to 1) examine FUV/visible albedo variations as a function of surface type (e.g., mare versus highlands), 2) test the hypothesis that FUV albedo is diagnostic of surface weathering exposure age (materials exposed to space tend to darken more quickly at UV wavelengths than at visible and longer wavelengths), and 3) provide ``ground-truth'' FUV data for comparison with future UV images of asteroids, planetary satellites, and other atmosphereless solar system bodies. Progress in these areas will be presented at the meeting. We would like to acknowledge the excellent job done by the team of engineers, scientists, and astronauts in charge of pointing, and NASA's Astro-2 Guest Investigator project for support.
Monday program listing