This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A Ph.D. student at the University of Sydney has produced the first comprehensive classification system and map of Martian soils, creating a new framework that could help scientists compare landscapes across the Red Planet and identify promising locations for future exploration, habitation and food production. The research, led by Daniel Irving from the Sydney Institute of Agriculture and the Faculty of Science, proposes a new term for Martian soil classes: "areths," derived from Ares, the Greek name for Mars.
Published in the journal CATENA, the research uses orbital observations and models to classify almost 800 million locations across Mars into a hierarchy of 2,000 soil classes and presents a global map showing where they occur. "This is the first time a classification system of this scale has been developed for Martian soils," Irving said. "Scientists have mapped Mars' geology, mineralogy and chemistry before, but our system brings together multiple properties into a single framework, helping us understand how different Martian soils relate to one another and where they're found." Irving's supervisor, professor Alex McBratney, said, "A future greenhouse on Mars would need more than air, water and light.
Its builders would also need to know what lies beneath to understand better starting points for growing plants." The Provisional Polythetic Areth Classification System, or PPACS, groups Martian soils into 10 major "realms," 100 "assemblages" and 2,000 detailed "forms," based on properties including texture, mineralogy, pH and profile thickness. The classification is accompanied by a detailed map covering 92% of the Martian surface, allowing researchers to visualize the distribution of different soil types. The prospect of growing crops on Mars has long captured the public imagination, most famously in the film "The Martian," in which astronaut Mark Watney, played by Matt Damon, survives by growing potatoes in Martian soil.
While a greenhouse on Mars remains firmly in the future, Irving's research offers a scientific starting point for understanding which Martian soils might be best suited to supporting plant growth under controlled conditions. As a proof of concept, the researchers assessed all 2,000 soil classes for characteristics important to plant production, including water-holding capacity, pH, profile thickness, clay content and gravel content. One soil class, known as Nohibareth, emerged as the most promising candidate, scoring 0.93 on the study's zero-to-one grading scale.
Nohibareth's modeled average profile includes a pH of 6.8, 72% clay, minimal sand or gravel and an estimated water-holding capacity of 202 millimeters per meter. The map places this class particularly in the midlatitudes of Mars, around Tharsis, central Arabia Terra and Elysium Planitia. Nohibareth soils are found on 0.14% of Mars' surface.
These areas are candidates for closer investigation, not selected greenhouse sites. Among the assessed properties, water-holding capacity was the limiting factor in 73% of forms studied. Classes in the Fareth to Mareth realms all scored below 0.3 in this initial test, reflecting less favorable combinations of the properties considered.
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