A new study led by Candice Bedford, a research scientist in Purdue University’s Department of Earth, Atmospheric, and Planetary Sciences, and published in Communications Earth & Environment, shows that the Margin Unit did not record a single lakeshore environment. Instead, the rocks preserve a layered history of multiple, distinct episodes in which water of different origins and temperatures moved through, altered, and reworked the crust. Groundwater percolated through fractures and left carbonate deposits behind. Lake water or evolving groundwater systems chemically transformed minerals that had formed earlier. And in a final act, warm hydrothermal fluids pushed through the fractured bedrock, depositing vein minerals that recorded yet another chapter in the crater’s watery past. The Margin Unit, the team concluded, became a kind of crossroads where several aqueous systems converged over geological time.

Bedford and an international team of collaborators pieced together this history using measurements and images from Perseverance, particularly the data returned by the rover’s SuperCam instrument. SuperCam, mounted on the rover’s mast or head, combines remote chemical analysis techniques, including laser-induced breakdown spectroscopy, with high-resolution imaging, allowing scientists to determine the composition of rocks and individual mineral grains from a distance. That capability proved essential on the Margin Unit, where the crucial evidence was written at scales invisible from orbit: fine fractures, thin mineral veins, and subtle chemical variations between grains that together revealed a sequence of water-rock interactions spanning a long stretch of Martian history.

“If there is one thing I have learned after 10 years working with Mars rovers, it is that Mars constantly throws surprises at you,” Bedford said. “It is very rare that things are as we expect them to be from orbital data. They are usually far more complex and interesting, which is what makes planetary exploration so exciting.” Her comment captures a recurring lesson of the Mars 2020 mission: orbital spectroscopy can flag promising locations, but only close-up, grain-scale analysis can reveal the true sequence of geological events preserved in the rocks.

The oldest chapter of the story begins deep underground. At higher elevations within the Margin Unit, Perseverance encountered coarse, crystalline rocks rich in olivine, an iron-magnesium silicate mineral commonly associated with igneous processes. The chemistry and texture of these olivine-bearing rocks suggest that they originally formed from a magma that cooled slowly beneath the Martian surface, allowing large crystals to grow. In other words, the foundation of the Margin Unit is not sediment laid down on a lakebed but volcanic rock crystallized in the crust, later exposed and made available for alteration by whatever water arrived afterward. This igneous starting point matters, because it gives scientists a well-defined baseline against which every subsequent chemical change introduced by water can be measured.

The first watery episode left an unmistakable signature at lower elevations. The team identified carbonate-rich ridges cutting across the bedrock, evidence that groundwater once traveled through a network of fractures and precipitated minerals along its path. Bedford offered an analogy drawn from terrestrial plumbing: “The fractures are like pipes, and the carbonate is the Mars ‘limescale’ that eventually blocked the ‘pipes’ up.” Just as hard water leaves mineral scale inside household pipes, the Martian groundwater left carbonate crusts inside its fracture conduits, gradually sealing them. These carbonate fills record the chemistry of the fluids that deposited them and, by extension, the subsurface environment of early Mars, making them prime targets in the search for conditions that could once have supported microbial life.

The story did not end with the groundwater. The rover also found widespread silica distributed through the lower-elevation rocks, along with clear evidence that previously formed carbonates had been chemically altered. That combination points to a second, later episode of water-rock interaction, one that may have involved water from Jezero’s ancient lake spilling into the margin rocks or shifts in the groundwater system itself changing the composition and flow paths of subsurface fluids. Either way, the alteration of the earlier carbonates demonstrates that the region’s water history was not a single event but a sequence of overlapping processes, each overprinting and modifying the record left by the last.

The final chapter is perhaps the most surprising. Perseverance discovered a mineral vein containing fluorite and calcium sulfate, a chemical pairing that points to a hydrothermal episode occurring after the groundwater and lake-related alteration had already taken place. Fluorite, the mineral form of calcium fluoride, typically precipitates from warm, chemically distinctive fluids, and its presence alongside calcium sulfate suggests that heated waters moved through the fractured bedrock late in the crater’s history. Hydrothermal systems are of special interest to astrobiologists because on Earth they support thriving ecosystems independent of sunlight, making similar environments on Mars compelling places to look for signs of past life. The vein indicates that even after Jezero’s lake had faded from the scene, the crust beneath it remained geologically and hydrologically active.

Taken together, the findings fundamentally reshape how scientists view the Margin Unit and, by extension, the history of water in Jezero Crater and across Mars. “Before we arrived at the Margin Unit, the main hypothesis was that these carbonates formed from interaction with the lake that existed in Jezero Crater, but now we know that this location became a sort of crossroads for aqueous systems, which significantly altered the crystalline volcanic rocks that were originally there,” Bedford said. Environments where water and rock interact repeatedly over long periods are precisely the kinds of settings that intrigue scientists studying the possibility of life on Mars, because such systems can supply energy and chemical gradients that living organisms can exploit. The Margin Unit had long been considered a promising research target since orbiting spacecraft first detected its strong carbonate signatures, but only Perseverance’s close-up view could reveal the fractures, mineral veins, and individual grains that exposed its far more complex history.

The research drew on the collective expertise of the SuperCam team, which Roger Wiens, professor of Earth, Atmospheric, and Planetary Sciences at Purdue, has led since before the launch of NASA’s Mars 2020 mission. Briony Horgan, professor of planetary science at Purdue, contributed to the work and served as campaign science lead during Perseverance’s exploration of the Margin Unit, and former Purdue doctoral students Stephanie Connell and Brad Garczynski also played important roles. Bedford, Wiens, and Connell received support from NASA for the SuperCam instrument. During its traverse, Perseverance collected rock samples from the Margin Unit, sealing them in tubes for a future mission intended to carry them to Earth. In terrestrial laboratories, those samples will be analyzed with instruments far more sensitive than anything a rover can carry, allowing scientists to examine the environments recorded in the rocks at microscopic scales and to assess their potential to preserve signs of ancient habitability.

“I hope this work helps to reshape how scientists view the history of water in Jezero Crater and across Mars,” Bedford said. “Ultimately, I hope this study helps planetary scientists reconstruct the changing climate and habitability of early Mars and provides helpful context for future researchers when these cached Perseverance samples are returned to Earth to be analyzed for potential biosignatures.” The paper, titled “Lake- and groundwater-associated alteration of the olivine-rich Margin Unit in Jezero Crater, Mars,” was accepted for publication in Communications Earth & Environment. For now, the findings stand as a vivid reminder that planetary surfaces keep their secrets at scales that only surface missions can reach, and that the red planet’s ancient waters were not a single still lake but a dynamic, evolving system whose shifting flows left an intricate, overlapping archive in the rocks along Jezero’s rim.

Subject of Research: Alteration of the olivine-rich Margin Unit in Jezero Crater, Mars, by groundwater, lake water, and hydrothermal fluids as observed by the Perseverance rover

Article Title: Purdue-led study finds an ancient history of water on Mars that shifted over time

Article References: Purdue-led study finds an ancient history of water on Mars that shifted over time. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Mars, Perseverance rover, Jezero Crater, Margin Unit, carbonates, groundwater, hydrothermal activity, SuperCam, olivine, astrobiology, water-rock interaction, Purdue University

The study, published as the inaugural article in the journal Space and Planetary Resources, was conducted by Kevin M. Cannon of Ethos Space Corp. and the Colorado School of Mines. Drawing on decades of laboratory analyses of nearly 400 martian meteorites and on in-situ measurements from the Spirit, Opportunity, Curiosity, Perseverance and Zhurong rovers, Cannon compiled the highest reported concentrations of 83 naturally occurring elements on Mars and compared them with the grades of ore deposits mined on Earth. The work arrives, he argues, at an inflection point between what may be the last large robotic science missions to Mars and the first serious steps toward commercialization and human landings.

A central theme of the analysis is that past discussions of planetary resources have often stumbled into logical errors that the terrestrial mining industry abandoned long ago. The most common is the presence-versus-absence fallacy: asking whether an element exists on Mars at all, when modern mass spectrometers can detect parts per trillion in virtually any material. What matters, Cannon stresses, is concentration, or grade, in a specific raw material at a specific location, because the energy and cost of extraction rise exponentially as grade falls. A gold mining company does not care how much gold is in Earth’s crust; it cares about the grade of a particular deposit. Similarly, the speciation of an element into separable ore minerals, such as zircon or monazite, versus lattice-bound substitutions in silicates, can make the difference between a practical resource and an impractical one.

The comparison baseline matters too. Average crustal composition is the wrong yardstick; martian concentrations must be measured against actual terrestrial ore bodies, which are enriched many orders of magnitude above bulk crust. When that comparison is made, the results span more than five orders of magnitude, with a median ratio of 27, meaning terrestrial ores are on average 27 times richer than the best-known martian materials. Six elements, including oxygen, sulfur, germanium, rubidium, argon and xenon, match or exceed the concentrations of the materials they are extracted from on Earth. Volatile elements such as sulfur, chlorine and bromine sit close to terrestrial ore grades, consistent with Mars having accreted from more volatile-rich building blocks. By contrast, the light metals lithium, beryllium and boron, the platinum group elements, the light rare earths, and the nuclear fuels thorium and uranium are orders of magnitude depleted in known martian samples.

Perhaps the most striking conclusions concern specific deposit types that rovers may have already brushed against. In Gale crater, ChemCam on the Curiosity rover detected copper enrichments throughout the stratigraphy of Mount Sharp, with the highest values in the Kimberley Formation. Detailed analysis suggests the copper occurs both in detrital grains of the potassic sandstones and adsorbed on manganese oxide coatings, pointing toward a porphyry copper or impact-hydrothermal deposit somewhere in the sediment source region. That would be a remarkable finding, because earlier theoretical work had specifically predicted that porphyry copper deposits should not exist on Mars, a prediction made before the discovery of evolved, potassic igneous lithologies and the full extent of ancient water-rock interaction on the planet.

At Jezero crater, the Perseverance rover has found strongly correlated nickel and copper enrichments in highly altered, aluminum-rich float rocks, with ore-grade values that support the long-standing prediction of Ni-Cu-PGE sulfide deposits associated with ultramafic volcanism. The region’s extensive olivine-rich unit, mapped from orbit and confirmed on the ground by an olivine cumulate outcrop on the crater floor, fits the terrestrial analog of large igneous provinces where such sulfide ores segregate from lava flows. Perseverance’s PIXL instrument has also detected lamellar bands of zirconium, titanium, chromium and phosphorus-bearing dense grains in deltaic sediments, evidence for heavy mineral lag deposits of the kind mined on Earth for ilmenite and zircon. Cannon notes that in all three cases the enriched materials were transported by water away from their sources, leaving only shadows of the original ore bodies, much as the California gold rush began in creek beds before prospectors traced the gold back to hard rock.

The quantitative picture is sharpened by extrapolation from element-element correlations in the meteorite collection. A single SuperCam point at Jezero reporting up to 2000 parts per million copper, if taken at face value, would predict roughly 2.2 parts per million ruthenium based on the meteorite correlation, exceeding typical terrestrial platinum-group ore grades even though the value falls below rover detection limits. Similarly, a PIXL spot measuring 1.4 weight percent zirconium, attributed to zircon or baddeleyite, implies about 362 parts per million hafnium, slightly above terrestrial ore values. These calculations suggest that ore-quality enrichments may already have been encountered on rover traverses, hidden below the sensitivity of onboard instruments, and that only a tiny fraction of the martian surface has been examined at all.

Mapping the indicators globally reveals a crucial geographic pattern. Olivine detections, potassium- and thorium-rich alkali terrains, aluminum clay exposures and fan-shaped sedimentary landforms, the best orbital proxies for sulfide, porphyry-like, leached and placer deposits respectively, cluster largely in equatorial regions such as Nili Fossae, Mawrth Vallis and eastern Valles Marineris. The mid-latitudes, where shallow ground ice is abundant, show a notable absence of these indicators, partly because younger lava flows, plains deposits and ice-dust mantles bury the ancient Noachian units where ores are most likely. This creates a potential tradeoff for settlement planning: if water is mined from ground ice, prospecting for metals may be pushed to marginal zones, but if water comes from hydrated minerals or other equatorial sources, the richest known mineral provinces become accessible. Atmospheric carbon dioxide and iron, available everywhere from regolith and iron meteorites, impose no such constraint.

Volumetrics remain a major uncertainty. The hematite-bearing unit at Meridiani Planum covers some 150,000 square kilometers, though its thickness is poorly known, while a native sulfur deposit recently discovered by Curiosity in Gediz Vallis has an estimated volume of 28,000 to 50,000 cubic meters. For the copper and nickel-copper signals at Gale and Jezero, the source deposits, if intact, likely exceed the transported materials in which they were detected, but elements like copper and nickel cannot yet be mapped from orbit. Cannon also flags unexplored geologic settings as prime targets for human fieldwork: evolved dacite terrains in Syrtis Major and the Eridania basin, impact-induced and magma-ice hydrothermal systems, speculative ancient seafloor deposits, and deeply leached aluminum clay stratigraphies like those at Mawrth Vallis, where extreme alteration hinted at by Jezero’s float rocks may have concentrated additional elements.

The bottom line is a sober but encouraging assessment. Mars falls between the Moon and Earth in its ore grades, as expected for a planet with intermediate geologic activity and water-rock interaction. Basic structural and industrial metals, including iron, aluminum, manganese, chromium, copper, zinc and titanium, show promising enrichments detectable with current orbital and geomorphologic data and should be prioritized for an initial settlement, while elements like lead, uranium and antimony are so depleted that substitution or import will likely remain necessary. As robotic exploration winds down and human missions approach, the study argues that the periodic table, not just the water cycle, must become the framework for choosing where on Mars to go and what to build when we get there.

Subject of Research: Assessment of non-volatile mineral and ore resources on Mars using meteorite and rover sample data

Article Title: Mineral resources of Mars based on decades of sample analysis

Article References: Cannon, K. M. (2025). Mineral resources of Mars based on decades of sample analysis. Space and Planetary Resources, 1(1), Article 1. https://doi.org/10.1007/s44461-025-00001-8

Image Credits: AI Generated

DOI: 10.1007/s44461-025-00001-8

Keywords: Mars, mineral resources, ore deposits, in-situ resource utilization, martian meteorites, Gale crater, Jezero crater, porphyry copper, Ni-Cu-PGE sulfides, heavy mineral sands, Perseverance rover, Curiosity rover