HR: 0800h
AN: SH51D-0293    [Abstracts]
TI: A Dynamic Fountain Model for Lunar Dust
AU: Vondrak, R R
EM: Richard.R.Vondrak@nasa.gov
AF: NASA Goddard Space Flight Center, Mail code 690, Greenbelt, MD 20771 United States
AU: * Stubbs, T J
EM: Timothy.J.Stubbs@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Mail code 690.4, Greenbelt, MD 20771 United States
AU: Farrell, W M
EM: William.Farrell@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Mail code 695, Greenbelt, MD 20771 United States
AB: 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 $\sim$10 cm above the surface, by suggesting that charged grains "levitate" in the local electric field; however this does not explain observations at $\sim$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. These dust grains may affect the optical quality of the lunar environment for astronomical observations and interfere with exploration activities.
DE: 6025 Interactions with solar wind plasma and fields
DE: 6213 Dust
DE: 6250 Moon (1221)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting