Estimating optimum launch velocity of electrostatically detached dust particles over sunlit locations on moon

Abstract

Microscopic fluctuations over sunlit locations on Moon due to dominant photoelectric charging might induce a sufficient fluctuating electric field that can electrostatically detach the overlying charged dust by overcoming surface adhesion and lunar gravity. A formulation based on the dynamical evolution of the statistical variables, viz., the mean charge and the variance, at microscopic scale is established to calculate the local charge and electric field fluctuations and illustrate this effect. The formulation has been coupled with the charged particle dynamics to derive the optimum launch velocity of the dust particles near the surface just after detachment. Fowler's treatment of the photoemission, dominant Extreme Ultraviolet (EUV) Lyman α radiation of the solar spectrum and subsequent collection of the emitted photoelectrons, measured particle size distribution of the regolith sample, and typical solar wind plasma have been consistently accounted for illustrating the concept. Our analysis suggests that the intense fluctuations in the electric field locally detach the submicron-charged particles with a launch velocity of a few ms-1-for instance, the charge fluctuations might induce ∼ 10 Mv/m field that can launch 100 nm particles with a speed of ∼5 ms-1.