Vital clue: NASA Curiosity's latest find shows Mars may have supported life until its CO₂ vanished
NASA believes that examining other sulfate-rich areas could validate these findings and further illuminate Mars’ transformation as its atmosphere dissipated.
- Apr 18, 2025,
- Updated Apr 18, 2025 4:54 PM IST
When NASA’s Curiosity rover landed on Mars in 2012, it began a journey that would eventually rewrite what we know about the planet’s potential to support life. Now, after more than a decade and 34 km of exploration, the rover has helped unearth a critical clue — evidence of an ancient carbon cycle buried deep in Mars’ Gale Crater. This finding, led by Dr Ben Tutolo of the University of Calgary, not only sheds light on the red planet’s climatic evolution but also brings scientists one step closer to answering a long-standing question: was Mars ever truly habitable?
As Curiosity drills through the sulfate-rich layers of Mount Sharp in Gale Crater, the team’s focus is squarely on tracing the planet’s climate shifts and assessing its ancient habitability. Their latest breakthrough, published in Science, reveals the presence of siderite — an iron carbonate mineral — at three separate drill sites.
“The discovery of large carbon deposits in Gale Crater represents both a surprising and important breakthrough in our understanding of the geologic and atmospheric evolution of Mars,” says Dr. Ben Tutolo, a participating scientist on the NASA Mars Science Laboratory team.
Reaching these strata had long been a key objective for the mission, and the findings are adding crucial context to Mars’ transition from a once warm, wet world to the cold and dry terrain we see today.
“The abundance of highly soluble salts in these rocks and similar deposits mapped over much of Mars has been used as evidence of the 'great drying' of Mars during its dramatic shift,” Tutolo explains.
Though scientists had predicted that sedimentary carbonate could form under Mars' CO₂-rich ancient atmosphere, concrete identifications had been rare—until now. This discovery suggests that the early Martian atmosphere held enough carbon dioxide to maintain liquid water. As the atmosphere thinned over time, some of that CO₂ was locked away in rock form.
NASA believes that examining other sulfate-rich areas could validate these findings and further illuminate Mars’ transformation as its atmosphere dissipated.
“It tells us that the planet was habitable and that the models for habitability are correct,” Tutolo says. “The broader implications are the planet was habitable up until this time, but then, as the CO₂ that had been warming the planet started to precipitate as siderite, it likely impacted Mars' ability to stay warm.”
The key question now is how much atmospheric CO₂ was sequestered — and whether that loss played a role in Mars’ declining habitability.
Tutolo also draws a direct connection to his Earth-based research, which explores turning human-made CO₂ into carbonates as a climate strategy.
“Learning about the mechanisms of making these minerals on Mars helps us to better understand how we can do it here,” he said. “Studying the collapse of Mars' warm and wet early days also tells us that habitability is a very fragile thing.”
For Tutolo, the findings underscore how delicate planetary habitability can be. “The most remarkable thing about Earth is that it's habitable and it has been for at least four billion years,” he added. “Something happened to Mars that didn't happen to Earth.”
When NASA’s Curiosity rover landed on Mars in 2012, it began a journey that would eventually rewrite what we know about the planet’s potential to support life. Now, after more than a decade and 34 km of exploration, the rover has helped unearth a critical clue — evidence of an ancient carbon cycle buried deep in Mars’ Gale Crater. This finding, led by Dr Ben Tutolo of the University of Calgary, not only sheds light on the red planet’s climatic evolution but also brings scientists one step closer to answering a long-standing question: was Mars ever truly habitable?
As Curiosity drills through the sulfate-rich layers of Mount Sharp in Gale Crater, the team’s focus is squarely on tracing the planet’s climate shifts and assessing its ancient habitability. Their latest breakthrough, published in Science, reveals the presence of siderite — an iron carbonate mineral — at three separate drill sites.
“The discovery of large carbon deposits in Gale Crater represents both a surprising and important breakthrough in our understanding of the geologic and atmospheric evolution of Mars,” says Dr. Ben Tutolo, a participating scientist on the NASA Mars Science Laboratory team.
Reaching these strata had long been a key objective for the mission, and the findings are adding crucial context to Mars’ transition from a once warm, wet world to the cold and dry terrain we see today.
“The abundance of highly soluble salts in these rocks and similar deposits mapped over much of Mars has been used as evidence of the 'great drying' of Mars during its dramatic shift,” Tutolo explains.
Though scientists had predicted that sedimentary carbonate could form under Mars' CO₂-rich ancient atmosphere, concrete identifications had been rare—until now. This discovery suggests that the early Martian atmosphere held enough carbon dioxide to maintain liquid water. As the atmosphere thinned over time, some of that CO₂ was locked away in rock form.
NASA believes that examining other sulfate-rich areas could validate these findings and further illuminate Mars’ transformation as its atmosphere dissipated.
“It tells us that the planet was habitable and that the models for habitability are correct,” Tutolo says. “The broader implications are the planet was habitable up until this time, but then, as the CO₂ that had been warming the planet started to precipitate as siderite, it likely impacted Mars' ability to stay warm.”
The key question now is how much atmospheric CO₂ was sequestered — and whether that loss played a role in Mars’ declining habitability.
Tutolo also draws a direct connection to his Earth-based research, which explores turning human-made CO₂ into carbonates as a climate strategy.
“Learning about the mechanisms of making these minerals on Mars helps us to better understand how we can do it here,” he said. “Studying the collapse of Mars' warm and wet early days also tells us that habitability is a very fragile thing.”
For Tutolo, the findings underscore how delicate planetary habitability can be. “The most remarkable thing about Earth is that it's habitable and it has been for at least four billion years,” he added. “Something happened to Mars that didn't happen to Earth.”