Size and charge distribution characteristics of fine and ultrafine particles in simulated lunar dust: Relevance to lunar missions and exploration

Abstract

Astronaut anecdotal data, biologic studies, and multi-perspective reports indicate that lunar dust will be a significant hindrance to exploring the Moon, both robotically and by humans. Hence, important characteristics of the lunar dust must be established. Critically needed are detailed particulate matter size, dust cloud concentration, and charge distribution analyses to determine the viability of methods for real-time measurement on the lunar surface. In this study, we applied various state-of-the-art aerosol measurement techniques to characterize fine (0.1–2.5 ​μm) and ultrafine (<0.1 ​μm) JSC-1A lunar simulant particles. The different techniques were assessed at 1 ​atm and evaluated for viability on the lunar surface (i.e., hard vacuum). To represent suspended dust, the simulant was dispersed as an aerosol and size distributions were measured in real-time using multiple aerosol instruments. Results show a unimodal distribution centered at approximately 0.2 ​μm, in fair agreement with previously reported measurements. To demonstrate portability and networkability, two low-cost particulate matter sensors were evaluated for measurement of suspended dust concentration. Strong correlations with an industry standard instrument support the potential candidacy of these sensors for future in-situ measurements on the Moon. Evaluating the capability of compact, low-cost instruments and larger, more robust instruments to precisely and accurately measure particle size distributions is a critical step to determine the prospect of measuring particulate matter with lightweight sensors in multiple lunar environments. In addition, assessing the compact instrument mass, power, portability, complexity, and measurement speed will provide key guidance into mitigating dust-related challenges to future lunar missions.