HR: 0830h
AN: P21D-12    [Abstracts]
TI: A Dynamic Fountain Model for Dust in the Lunar Exosphere
AU: * Stubbs, T J
EM: tstubbs@lepvax.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 United States
AU: Vondrak, R R
EM: Richard.R.Vondrak@nasa.gov
AF: NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 United States
AU: Farrell, W M
EM: William.M.Farrell@nasa.gov
AF: NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 United States
AB: From the Apollo era there is much evidence to show that lunar horizon glow observed at the terminator is caused by sunlight scattered by dust grains originating from the surface. The dust grains and lunar surface are electrically charged by the moon's interaction with the local plasma environment and the photoemission of electrons due to solar UV and X-rays. This causes the like-charged surface and dust particles to repel each other, and creates a near-surface electric field. Previous models have explained dust observations at ~10 cm above the surface, by suggesting that charged grains "levitate" in the local electric field; however this does not explain observations at ~1 km altitude. In order to explain the high-altitude dust observations, we propose a dynamic "fountain" model in which charged dust grains follow ballistic trajectories, subsequent to being accelerated upwards through a narrow sheath region by the surface electric field. The affect of different surface electric field profiles and adhesion of grains to the surface is also investigated. These dust grains will affect the optical quality of the lunar environment for astronomical observations and interfere with exploration activities.
DE: 5421 Interactions with particles and fields
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly