A recent discovery by NASA’s Perseverance rover has uncovered evidence that water shaped certain regions of Mars in more complex ways than researchers previously thought.
While NASA has confirmed the presence of water on Mars in the past, mostly in the form of surface ice and possible deep reservoirs of liquid water, the new research revealed multiple episodes of ancient lake activity, groundwater, and heated underground fluids helping to shape the Martian environment.
The discovery comes from the rover’s exploration of the “Margin Unit,” a geological region along the inner edge of Jezero Crater. Perseverance reached the area in September 2023, where scientists initially expected to find sedimentary rocks formed from material deposited in an ancient lake.
Instead, the rover found igneous rock that recorded repeated interactions with water.
Published in Communications Earth & Environment, the study suggests the Margin Unit became a kind of geological crossroads where different water systems interacted with the Martian surface and subsurface at different points in the planet’s history.
“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,” Candice Bedford, a research scientist at Purdue University in West Lafayette, Indiana, and the study’s lead author, says in a statement.
“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,” Bedford adds.
The evidence comes from Perseverance’s SuperCam instrument, which analyzes rocks by firing laser pulses and studying the resulting plasma to determine chemical composition. In total, the rover has reviewed 185 bedrock targets across the Margin Unit.
Recent investigations by Perseverance revealed coarse-grained, olivine-rich rock that showed little evidence of water alteration. Scientists believe this rock originally formed deep underground as magma slowly cooled, allowing large mineral crystals to develop. It was later exposed at the surface as overlying material eroded.
“If there is one thing I have learned after 10 years working with Mars rovers, it is that Mars constantly throws surprises at you,” said Bedford. “It is very rare that things are as we expect them to be from orbital data.”
When looking at the geological sequence, however, the rocks do indeed tell a different story.
The olivine grains were fractured and surrounded by silica and carbonate minerals, evidence that water had interacted with the rock. Here on Earth, similar reactions involving olivine can produce hydrogen, which some microorganisms can use as an energy source. Carbonate and silica can also preserve chemical evidence of ancient environments.
Carbon-rich groundwater altered the olivine, while Jezero’s ancient lake left silica-rich minerals behind. Additionally, Perseverance found fluorite and calcium sulfate veins, suggesting Mars’ region experienced a later episode of hot, hydrothermal water activity.
Understanding these findings could help scientists reconstruct Mars’ water history, climate, and potential habitability.
“I hope this work helps reshape how scientists view the history of water in Jezero Crater and across Mars,” Bedford said.
“Ultimately, I hope it helps planetary scientists reconstruct the changing climate and habitability of early Mars.”
Chrissy Newton is a PR professional and the founder of VOCAB Communications. She currently appears on The Discovery Channel and Max and hosts the Rebelliously Curious podcast, which can be found on YouTube and on all audio podcast streaming platforms. Follow her on X: @ChrissyNewton, Instagram: @BeingChrissyNewton, and chrissynewton.com. To contact Chrissy with a story, please email chrissy @ thedebrief.org.