NASA’s Perseverance rover has discovered that Mars’ Jezero Crater hosted complex water systems on multiple occasions, uncovering igneous rocks modified by groundwater and hydrothermal activity rather than simple lake sedimentation. The findings, published in September 2024, reshape scientific understanding of early Martian habitability.
When NASA’s Perseverance rover arrived at the inner edge of Mars’ Jezero Crater in September 2023, mission scientists expected a straightforward shoreline. Known as the Margin Unit,
the geologic band hugs an ancient Martian lakebed where researchers anticipated finding sedimentary deposits of clay and silt. On Earth, such layered sedimentary environments excel at preserving traces of past microbial life.
Instead, the rover encountered igneous rock formed deep underground from molten magma or surface volcanic activity. Rather than disrupting the scientific timeline, this volcanic baseline preserved an intricate, multi-step diary of water movement across early Mars. The results of the analysis were published in September 2024 in the journal Communications Earth & Environment.
SuperCam Analysis Across 185 Bedrock Targets
To unravel the site’s geology, the science team utilized the SuperCam instrument mounted on the rover’s mast. By firing a laser up to 21 feet (6.5 meters) away, the instrument analyzes the spectrum of resulting plasma to determine mineralogy based on reflected light. Across an elevation range of roughly 870 feet (265 meters) in the Margin Unit, the rover examined more than 185 bedrock targets.
That detailed remote sensing revealed three distinct aqueous episodes, proving that the crater rim functioned as a dynamic crossroads for different fluid systems rather than a single static shoreline.
“Before we arrived at the Margin Unit, the main hypothesis — derived from orbital observations — was that the carbonate seen from orbit formed from interaction with the lake that existed in Jezero Crater,” said Candice Bedford, a research scientist at Purdue University in West Lafayette, Indiana, and the study’s lead author. “But now we know that this location became a sort of crossroads for aqueous systems. 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.”
Candice Bedford, research scientist at Purdue University in West Lafayette, Indiana
Three Distinct Episodes of Water Interaction
The first episode began long before the lake filled the basin, originating from coarse-grained olivine rocks formed in deep magma chambers. As ground above eroded away, carbon-dioxide-rich groundwater seeped into fractures within the exposed olivine, triggering chemical reactions that left behind prominent ridges of carbonate minerals.
A subsequent second episode tied directly into the ancient crater lake. Water from the lake interacted with the fractured olivine, leaving behind silica deposits especially concentrated below the old water line.
“Turning olivine into carbonate can leave silica behind, and we see more of that silica in rocks that sat below the water line.”
Eleni Ravanis, co-author and planetary scientist at the University of Hawaii at Manoa
Finally, Perseverance discovered mineral veins containing calcium sulfate and fluorite in the eastern Margin Unit. These formations indicate a third, much hotter phase where thermal fluids circulated through the volcanic bedrock much like a terrestrial hot spring system.
Implications for Ancient Life and Future Study
While the rover team mapped the sequence of these interactions, determining their exact chronological ages remains challenging. Hydrothermal systems and carbonate-silica interactions are prime targets for astrobiology because they create environments capable of supporting microbes and locking organic traces into mineral structures.
“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 in the statement. “It is very rare that things are as we expect them to be from orbital data. I hope this work helps reshape how scientists view the history of water in Jezero Crater and across Mars. Ultimately, I hope it helps planetary scientists reconstruct the changing climate and habitability of early Mars.”
Candice Bedford, research scientist at Purdue University
The rover has cached multiple samples from the formation.
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