NASA’s Perseverance rover has uncovered evidence of three distinct water interactions in Jezero Crater, reshaping understanding of Mars’ ancient hydrological history. The findings, published in Communications Earth & Environment, reveal a complex interplay of groundwater, lakes, and hydrothermal activity that altered the region’s rocks over billions of years.
The Perseverance rover’s exploration of the “Margin Unit” in Jezero Crater has challenged previous assumptions about Mars’ aqueous past. Instead of sedimentary rocks, scientists found igneous formations that recorded at least three episodes of water interaction, according to a study led by Purdue University researcher Candice Bedford. These discoveries, derived from over 185 bedrock analyses using the rover’s SuperCam instrument, suggest Mars’ water systems were far more dynamic than previously thought.
The Margin Unit findings are important because Jezero Crater sits inside one of the largest exposures of carbonate on Mars, so what we learn here reaches well beyond this crater. The Perseverance rover captured the data used in this panorama of the “Margin Unit,” a geologic area that hugs the inner edge of Jezero Crater’s rim, between October 8 and October 16, 2023. The rover examined the Margin Unit over approximately 870 feet (265 meters) of elevation. At the higher parts of the area, the rover encountered coarse, crystalline rock rich in olivine. These rocks showed very little evidence of past contact with water. Olivine contains magnesium and iron.
Three Episodes of Water Activity
The first episode involved carbon-dioxide-rich groundwater reacting with olivine, creating carbonate ridges in lower elevations. This process, observed in rocks near the ancient lakebed, left behind silica deposits that scientists now associate with the second episode—water from the lake itself. Turning olivine into carbonate can leave silica behind, and we see more of that silica in rocks that sat below the water line,
noted Eleni Ravanis of the University of Hawaii at Manoa.
The third and final episode, identified in the eastern Margin Unit, involved hot groundwater that formed mineral veins about 25 centimeters thick, containing calcium sulfate and fluorite.
At the higher elevations, the rover encountered coarse, crystalline rock containing the mineral olivine. These rocks showed very little evidence of past contact with water. The situation was very different farther down the Margin Unit, near the ancient lakebed. There, the olivine appears heavily altered. Its grains are fractured, and silica fills spaces between them. Carbonate and silica are especially interesting to scientists searching for signs of ancient habitability.
SuperCam’s Role in Decoding Martian Geology
The rover’s SuperCam instrument, which uses laser-induced plasma to analyze rock chemistry, was critical in mapping the Margin Unit’s transformations. By examining 185 targets across 265 meters of elevation, scientists reconstructed the sequence of water interactions. At higher elevations, olivine-rich rocks showed minimal water alteration, while lower areas exhibited fractured grains and silica-filled spaces, indicating prolonged exposure to aqueous systems.
Before we got to the Margin Unit, the main hypothesis, drawn from observations from orbit, was that the carbonates seen from orbit formed in contact with the lake that existed in Jezero crater.
Bedford explains why this matters for the picture of the crater so far: But now we know that this place became a kind of crossroads of water systems.
SuperCam Reveals Mars’ Hidden Water History Much of this evidence came from SuperCam, an instrument mounted high on Perseverance’s mast. SuperCam can identify the mineral composition of geological features by analyzing the light they reflect. The detailed analysis of more than 185 bedrock points, carried out with the rover’s sophisticated SuperCam instrument, has revealed that the Martian soil contains formations of igneous and volcanic origin, instead of the expected lacustrine sediments.
Implications for Mars’ Habitability
The findings have significant implications for the search for ancient microbial life. Carbonate and silica, both linked to water activity, are known to preserve biosignatures on Earth. The presence of hydrothermal systems—similar to those that supported life in Earth’s deep oceans—suggests Mars may have once harbored conditions favorable to microbial survival.
A study published on September 21, 2026, highlights Jezero Crater's significance in understanding Mars' climatic evolution. As Perseverance continues its journey, the data collected from the Margin Unit will inform future missions seeking evidence of past life on the Red Planet. The rover has also explored the “Lac de Charmes” area, an area of valleys and ridges west of the Jezero crater rim that represent a wild west frontier
for the mission. The rocks in this area are among the oldest Perseverance has encountered.
Exploration has been boosted by a new algorithm that makes clever use of a processor originally used to communicate with the Ingenuity helicopter to achieve longer and more accurate drives. Perseverance’s exploration of the “Lac de Charmes” region is now nearing its end, but the discoveries certainly haven’t stopped. Recently, the science team sent the rover towards an area nicknamed “Idubi,” where hundreds of light-toned boulders were spotted from a distance. “Idubi” has proven to be a scientific bonanza, where rocks of varying texture and composition are concentrated.
When Perseverance investigated one of these light-toned boulders, an abrasion patch fittingly named “Badger Peak” revealed a spectacular light-and-dark texture (shown in the image above) unlike any the rover has seen before. An attempt to sample this boulder was unsuccessful due to its high hardness, so the team is now searching elsewhere for a similar rock to sample. The rover has created a total of 13 abrasion patches on rocks that caught the team’s attention, providing a feast of scientific data.