Lunar regolith control and resource utilization

Abstract

The major process for weathering and erosion on the moon is micro-meteorite impact. This produces the outer blanket of the moon known as lunar regolith or soil, which consists of numerous particles of various sizes. Lunar dust (defined as particles ≪20um) makes up about 20 wt% of the typical lunar soil. Dust contamination causes serious problems for equipment and vehicles vital to space mission applications. Lunar “weathering” has left the lunar soil with a relatively fine texture compared to terrestrial dust particle size distributions. The electrostatic charging of the lunar surface is caused by its interaction with the local plasma environment and solar UV and X-ray induced photoemission of electrons. According to observations by astronauts, lunar dust is electrostatically charged, difficult to remove, and appears to get everywhere. The lunar thermal environment poses a unique challenge to materials since it is characterized by large temperature variations, long hot and cold soak times, and reduced heat rejection capability due to the presence of the lunar regolith. Previous investigations have indicated a lunar regolith deposition rate of about 1 cm per 2–3 million years, but the deposition rate is expected to be both geographically variable and also to vary over time. Dust gathers on sensors and actual pieces of the vehicle inhibiting motion and data gathering. Devices that require transparency to light for maximum efficiency such as solar photovoltaic power systems, video cameras, optical or infrared detectors, and windshields for various types of vehicles including rovers and spacecraft will suffer from the dust accumulation. Another potential hazard is the unintentional capture of extraterrestrial bacteria or spores on the surfaces of the equipment, to the extent that can be anticipated, that might bring inadvertent and possibly catastrophic contamination of human environment. We are attempting to design an integrated approach to solving the dust problems and to actually leverage the unique properties associated with the lunar regolith's many elements through insitu resource utilization and processing. This paper highlights some of the aspects of cost-effective, lightweight, self-cleaning and anti-contamination coatings to mitigate accumulation of lunar dust on critical power and optical system elements and some unique approaches to lunar regolith processing to extract potentially valuable resources that can be used to support a lunar habitat.