HR: 1400h
AN: SM23B-04    [Abstracts]
TI: Surface Charging on Airless Bodies
AU: * Halekas, J S
EM: jazzman@ssl.berkeley.edu
AF: Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720, United States
AU: Delory, G T
EM: gdelory@ssl.berkeley.edu
AF: Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720, United States
AU: Brain, D A
EM: brain@ssl.berkeley.edu
AF: Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720, United States
AU: Lin, R P
EM: rlin@ssl.berkeley.edu
AF: Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720, United States
AU: Stubbs, T J
EM: Timothy.J.Stubbs.1@gsfc.nasa.gov
AF: Goddard, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States
AU: Stubbs, T J
EM: Timothy.J.Stubbs.1@gsfc.nasa.gov
AF: Goddard Earth Sciences and Technology Center, University of Maryland, Baltimore County, Baltimore, MD 21250, United States
AU: Farrell, W M
EM: William.M.Farrell.1@gsfc.nasa.gov
AF: Goddard, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States
AB: Although the Moon and asteroids are often thought of as having relatively dormant environments, in fact the Moon at least is very electrically active. The surfaces of airless bodies are directly exposed to solar UV and X-rays, as well as solar wind plasma and energetic particles. This bombardment creates a complex electric field and plasma environment, with the surface typically charging positive in sunlight and negative in shadow, and surface potentials varying over orders of magnitude in response to changing solar illumination and plasma conditions. We present the first efforts to derive the exact magnitude of the nightside lunar surface electric potential from orbit (which involves correcting for spacecraft charging effects), rather than the lower limits which have been derived before. We then compare these measurements to simple theoretical models and other predictions for lunar surface charging in shadow during quiet times. In addition, we present a complete survey of lunar surface charging (utilizing data from Apollo surface observations and Lunar Prospector orbital observations, in concert with theory and modeling) for all lunar locations and solar and plasma conditions, in order to demonstrate the wide range of charging conditions that can occur on airless bodies. By validating surface charging models for the Moon, we can gain confidence in the application of these models to other airless bodies such as asteroids, moons, and Mercury. It is important to have confidence in these theoretical tools, so we can apply them to problems such as dust levitation and transport - which may be of fundamental importance both at the Moon and on asteroids.
DE: 2756 Planetary magnetospheres (5443, 5737, 6033)
DE: 2780 Solar wind interactions with unmagnetized bodies
DE: 5421 Interactions with particles and fields
DE: 6025 Interactions with solar wind plasma and fields
DE: 6250 Moon (1221)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly