A Preliminary Study on the Effect of Lunar-Dust Movement on the Lunar Magnetic Field

Introduction: It is known that the present Moon has no global magnetic dipole field. Data from former lunar exploration programs show that the lunar magnetic field is very weak, usually just a few nT. Variations in field strength are noted in different lunar areas, e.g.: the average magnetic field in young basins and craters is between 0.5-1.5 nT, with exceptions that antipodal of Nectaris, Serenitatis, and Crisium field strength is greater than 11 nT and antipodal of Imbrian and Orientale field strength exceeds 34 nT. In contrast, the average magnetic field over the entire lunar surface is only ~4 nT while the average field outside the five antipodal regions is only 3 nT. The antipodal grooved and pitted terrains are the most strongly magnetic widespread lunar regions with average magnetic fields > 67 nT [1]. The origin of the lunar magnetic field is still a controversial topic. There are two principal ways to obtain information regarding the origin of the lunar magnetic field: one is from lunar samples collected during the former lunar-landing programs, and the second is from magnetic measurement data from lunar missions (such as Magnetometer and Electronic Reflector on the Lunar Prospector Orbiter). Charged lunar dust floats on the lunar surface [2] and the movement of charged particles should be able to generate an induced magnetic field. To the best of our knowledge, however, there is no study on how the movement of charged lunar dust could have impacted the lunar magnetic field. The purpose of the study is to design a model called " The Electromagnetic Induction Model of Charged Active Lunar Dust " based on the " Fountain Model " [3] and data from LEAM (Lunar Ejecta and Meteorites). The preliminary result shows that the contribution of the movement of charged lunar-dust to the lunar magnetic field is not negligible. The motion characteristics of lunar dust: Owing to the low-gravity and near vacuum of the lunar surface, tiny lunar soil particles from lunar regolith are liable to float off the lunar surface once they become disturbed by human or natural activities. These floating particles are lunar dust. The size (r d) of lunar dust is so small that particles are usually invisible to human eyes. These tiny particles have large specific surface areas and relatively good insulating properties so they can easily become charged under the low conductivity, high temperature and strong radiation conditions of …