Planetary pedology: New horizons for lunar resource mapping

Space agencies, private organizations, and advocacy groups are working to establish a sustainable human presence on the Moon and Mars in the coming decades, which necessitates in situ resource utilization. Regolith, the most accessible resource, offers opportunities to extract rare elements and produce high-strength structural materials for habitats. It could also serve as a substrate for food production, functioning similarly to soil on Earth, which is crucial for establishing future extraterrestrial human settlements. Much like the Industrial Revolution on Earth, the demand for resources requires detailed mapping of the surfaces of the Moon and Mars, raising questions about suitable mapping methods and the classification of incoherent materials. We propose that lunar regolith can be classified as soil and assess the applicability of established terrestrial soil nomenclatures, such as the World Reference Base for Soil Resources and the U.S. Soil Taxonomy, for this purpose. We conclude that these systems are not inherently applicable and would require substantial modifications and/or additions to accommodate the unique characteristics encountered. Consequentially, we advance a new nomenclature for lunar soils that highlights differences in pedogenic processes on the Moon, compared to those on Earth.