Washington DC [US], April 24 (HBTV): Research from NASA’s Curiosity rover has revealed evidence of a carbon cycle on ancient Mars, advancing scientists’ understanding of the planet’s past habitability.

Lead author Dr. Ben Tutolo of the University of Calgary, a participating scientist on the Mars Science Laboratory Curiosity team, and colleagues analysed samples from three drill sites within sulfate‑rich layers of Mount Sharp in Gale Crater. They identified siderite—an iron carbonate—indicating substantial carbon deposits in these strata.

“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,” said Tutolo. Reaching these carbonate‑bearing layers was a long‑term goal of the Curiosity mission, as they provide direct evidence of CO₂‑rich conditions necessary for liquid water on the surface.

Previously, sedimentary carbonates had been predicted to form under Mars’s ancient thick CO₂ atmosphere, but definitive identifications were rare. The presence of siderite suggests that Mars once maintained enough atmospheric carbon dioxide to sustain liquid water, before significant atmospheric thinning caused CO₂ to precipitate into rock.

Since its landing on August 5, 2012, Curiosity has traversed over 34 kilometres on Mars, exploring Gale Crater to understand climate transitions and habitability. The new findings, published this week in Science, bolster models of early Mars as a warm, wet world that later “greatly dried” into its present cold, arid state.

Future missions and analyses of other sulfate‑rich regions may confirm these results and further unravel Mars’s early history. Tutolo noted, “It tells us that the planet was habitable and that the models for habitability are correct. The broader implications are that the planet was habitable up until this time, but as CO₂ sequestration into siderite proceeded, Mars’s ability to stay warm was compromised.”

He added, “The question looking forward is how much of this CO₂ was actually sequestered? Was that potentially a reason we began to lose habitability?” The study underscores how small changes in atmospheric CO₂ can drive major shifts in a planet’s capacity to harbour life.

(ANI)