Micro-scale Electrostatic Structures formed on the Rough Surfaces of the Moon

TL;DR

This paper discusses the formation of micro-scale electrostatic structures on the Moon's rough surface, highlighting their potential role in dust mobilization and emphasizing the need for integrated research approaches.

Contribution

It introduces a comprehensive framework combining modeling, observations, and testing to better understand lunar surface charging phenomena.

Findings

Micro-scale electrostatic structures are formed on lunar surface due to charge separation.

These structures may influence dust mobilization on the Moon.

An integrated assessment approach is proposed for future research.

Abstract

It is widely accepted that the surface potential of the lunar dayside is "on average" several to 10 V positive due to photoelectron emission in addition to the solar wind plasma precipitation. Recent studies, however, have shown that an insulating and rough regolith layer tends to make positive and negative charges separated and irregularly distributed on sub-Debye-length scales. The local charge separation then gives rise to an intense and structured electrostatic field. Such micro-scale electrostatic structures lie in the innermost part of the photoelectron sheath and may contribute to the mobilization of the charged dust particles. Since the electrostatic structures can take different states depending on the topography of the lunar surface, it is necessary to update the research approach. We have launched a research group to develop an integrated assessment framework that includes theoretical and numerical modeling, on-orbit observations, ground-based testing, and the development of charging measurement instruments, with the ultimate goal of comprehensively understanding the surface charging processes on the Moon.