Curiosity Rover Uncovers Surprising Evidence of Carbon Cycle on Mars

Recently, the Curiosity rover made a groundbreaking discovery of ancient lakes in Gale Crater. Carbonate mineral, in particular siderite, was revealed to be present, suggesting a previously unrecognized carbon cycle occurring on Mars. During its exploration of an ancient lakebed, the rover made a surprising find. During its operations from 2022-2023, it collected samples from rocks that transitioned from muddy clays to desiccated sulfates.

Siderite – identified in four separate samples – occurred in a characteristic band over an 89-meter wide swath of acidic plain. Curiosity’s onboard Advanced Science Laboratory performed a detailed compositional analysis of the samples. Those tests indicated that these samples contained 5 to 10 percent siderite by weight. University of Calgary geochemist Benjamin Tutolo was the study’s principal investigator. First author Paul Niles, a NASA astrobiologist, said this finding helps paint a picture of Mars’ climatic past.

“This provides a great explanation for where the missing carbonate is and how the ancient Martian atmosphere could have been thick enough to support liquid water on the surface,” – Janice Bishop

Of great importance is the discovery of siderite. It shows that Mars experienced a gradual, slow carbon cycle, eventually causing it to lose the habitable environment that was present billions of years ago. Siderite is created by water that has been weathered through rock. Its presence demonstrates that as Mars became drier, carbon dioxide (CO2) in the atmosphere fell drastically.

Tutolo highlighted the ramifications of this discovery, saying, “We think this is the great drying of Mars. It would imply that none of the life-supporting properties of our planet’s climate have stood the test of cosmic time. Siderite offers important clues as to the ultimate destiny of Mars’ former atmosphere of carbon dioxide. It provides new, critical clues about what Earth’s climate was like in the deep past.

Curiosity rover has been exploring a region where ancient lakes once teemed. The shift from muddy clays to sulfates reflects the onset of fundamental geological alterations. The discovery of siderite in these rocks offers insights into the environmental conditions that prevailed during the planet’s wetter periods.

Bishop said these findings are particularly significant because “Once CO2 goes down, it doesn’t come back up.” This comment is intended to highlight the adult effect of carbon loss on the long-term habitability of Mars.