Perseverance Finds Evidence of Hot Water on Mars

NASA’s Perseverance rover set out expecting to find rocks from an ancient lakeshore. What it actually found tells a far more complicated story about water on Mars.

Expecting a Lakeshore, Finding a Volcano

Since 2023, Perseverance has been exploring a region called the Margin Unit, which hugs the inner edge of Jezero Crater. Scientists had expected the area, based on observations from orbit, to consist of sedimentary rock deposited along the shoreline of the ancient lake that once filled the crater. Instead, the rover found igneous rock, material that originally formed underground from molten rock or through volcanic activity. Candice Bedford, lead author of a new study and a research scientist at Purdue University, said the team initially assumed the carbonate visible from orbit had formed through contact with the crater’s ancient lake, but the Margin Unit turned out to be something more like a crossroads where multiple water systems converged.

Three Episodes Written in Stone

Using Perseverance’s SuperCam instrument, researchers analyzed more than 185 bedrock targets across the region. Their analysis, published September 21 in the journal Communications Earth and Environment, identified evidence of at least three separate episodes of water interacting with the rock. In the earliest episode, carbon-dioxide-rich groundwater reacted with olivine, a mineral formed as magma slowly cooled, producing carbonate minerals within cracks in the rock. A later episode appears tied to Jezero’s ancient lake itself: some rocks contain silica, which forms when olivine reacts with water and shows up in particularly high concentrations in rock that once sat below the lake’s waterline.

A Hotter Chapter

The third and final episode the team identified was noticeably different. Mineral veins containing calcium sulfate and fluorite turned up in the eastern part of the Margin Unit, evidence that hot water once circulated through the volcanic rock there. Researchers can reconstruct the order in which these three episodes occurred, but they can’t yet pin down exactly when each one took place. Together, the sequence shows the Margin Unit wasn’t simply an old lakeshore. It functioned as a location where groundwater, surface water, and heated fluids all interacted with Martian rock over time.

What This Means for the Search for Life

On Earth, hydrothermal systems, places where hot water circulates through rock, can create conditions capable of supporting microbial life, which is part of why this finding interests scientists studying whether Mars was ever habitable. Bedford said the results reinforce a broader lesson from a decade working with Mars rovers: orbital data alone rarely tells the whole story. She hopes the work helps planetary scientists reconstruct how Mars’s climate and habitability changed over time, and the carbonate minerals identified in this study could ultimately help researchers pin down when, and where, conditions suitable for life may have existed on the planet.

Sources

This report draws on original coverage by Space.com, citing a NASA/JPL statement and the peer-reviewed study by Candice Bedford and colleagues, published in Communications Earth & Environment.