Lunar electric fields,surface Potential and Associated Plasma Sheaths

This paper reviews the electric field environment of the Moon. Lunar surface electric potentials are reported as follows: Solar Wind - Dayside: ø_o + 10 to + 18 V Solar Wind - Terminator: ø_o ç ? 10 to ? 100 V Electron and ion densities in the plasma sheath adjacent to each surface potential regime are evaluated and the corresponding Debye length estimated. The electric fields are then approximated by the surface potential over the Debye length. The results are: Solar Wind - Dayside: E_o ? 10 V m^?1 outward Solar Wind - Terminator: E_o ç 1 to 10 V m^?1 inward These fields are all at least 3 orders of magnitude higher than the pervasive solar wind electric field; however they are confined to within a few tens of meters of the lunar surface.