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It wasn鈥檛 long after Ben Tutolo started as a participating scientist on NASA鈥檚  team that he started to understand just how much information was being collected on the red planet.

鈥淵ou are getting blasted with data all the time, so you have to be able to take a step back whenever something really compelling comes down the line,鈥� says PhD, associate professor with the  in the

He took a step back last year to answer a longstanding question: Why are there no carbonates on Mars?

鈥淚f any of our models about atmospheric warming are correct, we know that you must have had a large amount of CO₂ on ancient Mars to stabilize liquid water. Which means there should have been interactions between the CO₂ and the basalts that make up the planet. You should have carbonate minerals on Mars,鈥� says Tutolo. 鈥淏ut nobody has ever been able to find them at the levels we would expect.鈥�

Until now.

Curiosity rover finds 鈥榣arge carbon deposits鈥� on Mars

Research from NASA鈥檚 Curiosity rover, , has found evidence of a carbon cycle on ancient Mars.

The paper reveals that data from three of Curiosity鈥檚 drill sites had siderite, an iron carbonate material, within sulfate-rich layers of Mount Sharp in Gale Crater.

鈥淭he 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,鈥� says Tutolo, a geochemist who鈥檚 the lead author on the paper.

Reaching the strata, he says, was a long-term goal of the Mars Science Laboratory mission.

鈥淭he abundance of highly soluble salts in these rocks and similar deposits mapped over much of Mars has been used as evidence of the 鈥榞reat drying鈥� of Mars during its dramatic shift from a warm and wet early Mars to its current, cold and dry state,鈥� explains Tutolo.

Sedimentary carbonate has long been predicted to have formed under the CO₂-rich ancient Martian atmosphere, but Tutolo says identifications had previously been sparse.

NASA鈥檚 Curiosity rover landed on Mars on Aug. 5, 2012, and has  on the surface.

Curiosity drills three to four centimetres down into the subsurface to study the chemical and mineral makeup.

鈥淒rilling though the layered Martian surface is like going through a history book,鈥� Dr. Thomas Bristow, PhD, a research scientist at NASA Ames and a co-author on the paper, says

The discovery of carbonate suggests that the atmosphere contained enough carbon dioxide to support liquid water existing on the planet鈥檚 surface. As the atmosphere thinned, the carbon dioxide transformed into rock form.

NASA says future missions and analysis of other sulfate-rich areas on Mars could confirm the findings and help to better understand the planet鈥檚 early history and how it transformed as its atmosphere was lost.

Life on Mars?

Scientists are ultimately trying to determine whether Mars was ever capable of supporting life 鈥� and the latest discovery brings them closer to an answer.

鈥淚t tells us that the planet was habitable and that the models for habitability are correct,鈥� says Tutolo.

鈥淭he broader implications are that 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鈥� ability to stay warm,鈥� he explains.

鈥淭he question looking forward is how much of this CO₂ from the atmosphere was actually sequestered? Was that potentially a reason we began to lose habitability?鈥�

The research, he adds, fits with his ongoing work on Earth 鈥� trying to turn anthropogenic CO₂ into carbonates as a climate change solution.

鈥淟earning about the mechanisms of making these minerals on Mars helps us to better understand how we can do it here,鈥� he says. 鈥淪tudying the collapse of Mars鈥� warm and wet early days also tells us that habitability is a very fragile thing.鈥�

Tutolo says it鈥檚 clear that small changes in atmospheric CO₂ can lead to huge changes in the ability of the planet to harbour life.

鈥淭he most remarkable thing about Earth is that it鈥檚 habitable and it has been for at least four billion years,鈥� he adds. 

鈥淪omething happened to Mars that didn鈥檛 happen to Earth.鈥�