A classification framework for mapping lunar soils

The ever-closer establishment of a sustainable human presence on the Moon requires a thorough mapping of its soil to support in situ resource utilization (ISRU): the identification, extraction, and use of local materials to support mission needs and reduce reliance on Earth-based supply chains. Lunar soils are a critical resource for extracting valuable elements, constructing habitats, and potentially serving as a growth substrate for food production. However, current knowledge of lunar soils is largely based on remote sensing, which lacks the resolution and accuracy needed for detailed resource planning. To address this challenge, planetary pedology has emerged. In this study, we (1) review the concept of soil and soil-forming factors in the lunar context; (2) identify seven pedogenic-like processes operating at the Moon's surface; (3) propose a classification system based on reference horizons and five lunar reference soil groups within the World Reference Base for Soil Resources framework or, alternatively, a new order and six suborders within the Soil Taxonomy framework; and (4) apply this system to the Apollo 15 deep core as a test case. By offering a structured way to assess and compare soil properties, our approach provides a foundation for evaluating ISRU potential across different lunar terrains. Reliable soil classification is essential for selecting extraction sites, planning infrastructure deployment, and optimizing resource utilization strategies. These frameworks aim to facilitate communication and enhance our understanding of lunar soils, thereby supporting both scientific exploration and practical applications.