New results from NASA’s Curiosity rover have shed light on a longstanding question about Mars' ancient atmosphere. Researchers have suspected that Mars once had a thick, carbon dioxide-rich atmosphere capable of supporting liquid water. However, evidence of carbonate minerals, which would form through interaction between carbon dioxide and surface rocks, had been elusive.
An upcoming study in Science presents data from three of Curiosity's drill sites which have identified siderite, an iron carbonate mineral, in the Gale Crater's sulfate-rich stratum on Mars. This evidence supports the theory of an ancient Martian atmosphere with enough carbon dioxide to sustain warmer conditions and liquid water.
"This discovery helps us understand the mechanisms that drove the two planets down very different paths," remarked Edwin Kite, associate professor of geophysical sciences at the University of Chicago.
The Curiosity rover, operational since its 2012 landing, employs a drilling technique to penetrate up to 1.5 inches into the Martian subsurface, analyzing samples via the CheMin instrument. "Drilling through the layered Martian surface is like going through a history book," explained Thomas Bristow, research scientist at NASA Ames.
The recently detected carbonates may have been obscured by other minerals, suggesting that future missions could uncover further insights into Mars' atmospheric and geological history. "The discovery of abundant siderite in the Gale Crater represents both a surprising and important breakthrough," noted Benjamin Tutolo of the University of Calgary.
Managed by NASA’s Jet Propulsion Laboratory in Pasadena, the Curiosity mission is a key part of NASA's efforts to understand Mars' past.
The study, "Carbonates identified by the Curiosity rover indicate a carbon cycle operated on ancient Mars," receives its funding from NASA, the Canadian Space Agency, and the UK’s Science and Technology Funding Council.
For more details, visit NASA's website.