Negative potentials above the day‐side lunar surface in the terrestrial plasma sheet: Evidence of non‐monotonic potentials

The Lunar Prospector (LP) Electron Reflectometer (ER) instrument conducted a series of measurements of the lunar surface potential in a variety of conditions. Occasionally, when the Moon was exposed to the terrestrial plasma sheet and in daylight, large, unexpected negative potentials (∼−500 V) were measured. In this paper, we compare LP ER measurements with one‐dimensional particle‐in‐cell simulations of the potential above the lunar surface when the Moon is exposed to both solar UV radiation and the terrestrial plasma sheet. The simulations show that large negative potentials will be measured by LP ER due to the presence of stable, non‐monotonic potentials. Implications of these measurements to other airless bodies in the solar system are also discussed.

[1]  E. Roussos,et al.  Surface charging of Saturn's plasma absorbing moons: theoretical estimations and comparisons with Cassini observations , 2010 .

[2]  Andrew R. Poppe,et al.  Simulations of the photoelectron sheath and dust levitation on the lunar surface , 2010 .

[3]  F. Mozer,et al.  Spacecraft charging and ion wake formation in the near-Sun environment , 2010, 1006.0760.

[4]  J. Halekas,et al.  Lunar Prospector measurements of secondary electron emission from lunar regolith , 2009 .

[5]  S. Robertson,et al.  Lunar Dust Levitation , 2009 .

[6]  J. Halekas,et al.  Lunar Prospector observations of the electrostatic potential of the lunar surface and its response to incident currents , 2008 .

[7]  M. Hudson,et al.  Extreme lunar surface charging during solar energetic particle events , 2007 .

[8]  Chong-oh Lee,et al.  Lunar Surface Charging During Solar Energetic Particle Events , 2007 .

[9]  David L. Mitchell,et al.  Large negative lunar surface potentials in sunlight and shadow , 2005 .

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

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

[12]  D. Mitchell,et al.  Evidence for negative charging of the lunar surface in shadow , 2002 .

[13]  Eos Sorce,et al.  Laboratory for Atmospheric and Space Physics , 2000 .

[14]  Hood,et al.  Lunar surface magnetic fields and their interaction with the solar wind: results from lunar prospector , 1998, Science.

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

[16]  R. Grard.  Photoemission on the surface of Mercury and related electrical phenomena , 1997 .

[17]  S. Barabash,et al.  Plasma and magnetic field effects associated with Phobos and Deimos tori , 1991 .

[18]  W. Ip.  Electrostatic charging and dust transport at Mercury's surface , 1986 .

[19]  David G. Sibeck,et al.  An ISEE 3 study of average and substorm conditions in the distant magnetotail , 1985 .

[20]  R. Lin,et al.  Measurement of lunar and planetary magnetic fields by reflection of low energy electrons , 1975 .

[21]  R. Lin,et al.  Energetic electron scattering from the lunar remanent magnetic field , 1974 .

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

[23]  J. Bvl.  Characteristics of the Lunar Photoelectron Layer in the Geomagnetic Tail , 1972 .

[24]  R. J. L. Grard,et al.  Photoemission from lunar surface fines and the lunar photoelectron sheath , 1972 .

[25]  J. H. Fu.  Surface potential of a photoemitting plate , 1971 .

[26]  R. Guernsey,et al.  Potential distribution surrounding a photo-emitting, plate in a dilute plasma , 1970 .