In those drill sites, Curiosity detected deposits containing an iron carbonate material called siderite. According to Ben Tutolo, a University of Calgary associate professor of Earth, Energy, and Environment Studies as well as a NASA Mars Science Laboratory Curiosity Rover team, the data marks a major moment in the search for extraterrestrial life.

Billions of years ago, Mars was warmer and wetter than today, perhaps because volcanoes belched enough carbon dioxide to create a blanketing atmosphere. But scientists have not been able to find many of the carbon-rich minerals they would have expected on the Martian surface had that been the case.