A DYNAMIC FOUNTAIN MODEL FOR DUST IN THE LUNAR EXOSPHERE

ABSTRACT From the Apollo era there is much evidence to show that the lunar “horizon glow” and “streamers” observed at the terminator are caused by sunlight scattered by dust grains originating from the Moon’s surface. A simple dynamic dust “fountain” model has previously been proposed to explain observations of submicron dust “lofted” to altitudes of ~100 km. In this model charged dust grains follow ballistic trajectories, subsequent to being accelerated upwards through a narrow sheath region by the surface electric field. Described here are the effects of including a more realistic exponentially decaying electric field (consistent with Debye shielding of a charged surface in a plasma). Also discussed are the different mechanisms by which highly charged dust grains can be generated at the lunar surface; in particular, the possible effects of triboelectric charging are considered. Dust in the exosphere will affect the optical quality of the lunar environment for astronomical observations, as well as interfere with future robotic and human exploration activities.

[1]  E. H. Walker,et al.  Electrostatic dust transport on the lunar surface , 1962 .

[2]  D. R. Criswell,et al.  Surveyor observations of lunar horizon-glow , 1974 .

[3]  H. Zook,et al.  Large scale lunar horizon glow and a high altitude lunar dust exosphere , 1991 .

[4]  M. Horányi,et al.  Experimental levitation of dust grains in a plasma sheath , 2002 .

[5]  J. Goree,et al.  Observation of Dust Shedding From Material Bodies in a Plasma , 1992 .

[6]  David R. Criswell,et al.  Horizon-glow and the motion of lunar dust , 1973 .

[7]  M. Horányi,et al.  Dust transport in photoelectron layers and the formation of dust ponds on Eros , 2005 .

[8]  R. Manka,et al.  PLASMA AND POTENTIAL AT THE LUNAR SURFACE , 1973 .

[9]  E. Whipple,et al.  Potentials of surfaces in space , 1981 .

[10]  Mihaly Horanyi,et al.  Experimental investigations on photoelectric and triboelectric charging of dust , 2001 .

[11]  William M. Farrell,et al.  IMPACT OF DUST ON LUNAR EXPLORATION , 2007 .

[12]  J. Mccoy,et al.  Photometric studies of light scattering above the lunar terminator from Apollo solar corona photography , 1976 .

[13]  D. R. Criswell,et al.  Evidence for a high altitude distribution of lunar dust , 1974 .

[14]  William M. Farrell,et al.  Lunar Surface Charging: A Global Perspective Using Lunar Prospector Data , 2007 .

[15]  W. Farrell,et al.  A Dynamic Fountain Model for Lunar Dust , 2005 .

[16]  C. Goertz,et al.  Dusty plasmas in the solar system , 1989 .

[17]  R. Vondrak,et al.  Effects of levitated dust on astronomical observations from the lunar surface , 1993 .

[18]  O. Havnes,et al.  Levitation and dynamics of charged dust in the photoelectron sheath above surfaces in space , 1998 .