Characterization of Lunar Dust Simulants by Automated Particle Analysis using Scanning Electron Microscopy

Understanding the physical and chemical properties of extraterrestrial dust is crucial for extended human and robotic exploration on the Moon or Mars. Lunar and Martian dust can affect everything from equipment and spacesuits to habitable spaces in the lunar modules and may also serve as a potential resource for future space missions. Due to limited availability of lunar dust from the Apollo missions, simulant materials have been manufactured to replicate specific properties of the dust for testing on Earth. A total of 8 commercial and government-based simulants provided by NASA, SolySys Mining, and Space Resource Technologies were analyzed by automated particle analysis using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The focus of the analysis was on the fine fraction of particles less than 20 micrometers. The fine size fraction has not been studied as extensively as the coarse fraction, but an understanding of the fine particle characteristics is essential for dust mitigation strategies. The behavior of dust particles in the small size fractions is vastly different than particles in the visible range. Transport and adhesion of particles below 20 micrometers pose risks to hardware and human health, and specialized microscopic characterization techniques are warranted. The automated SEM-EDS analysis provided data on size, shape, and elemental composition. Particle size distributions by number were determined as well as particle type concentrations based on elemental compositions. Optical and SEM relocation were also performed on the larger fraction of particles to correlate the color, surface morphology, and elemental composition. A comparison of the particle size distribution, elemental composition, and particle morphology was made between the lunar dust simulants and published data from Apollo mission studies.