Mars Siderite Discovery Reveals Clues To Ancient Life-Friendly Climate

NASA Mars exploration 2025

A mineral called siderite found in Martian rocks is giving scientists new clues that Mars may have once been much warmer and wetter, possibly even supporting life.

NASA’s Curiosity rover, which landed on Mars in 2012 to study whether the planet could have ever supported tiny life forms, discovered siderite in rock samples from three spots in Gale Crater during 2022 and 2023. Gale Crater is a huge basin with a mountain at its center, believed to have once held a lake.

Siderite is an iron carbonate mineral, and finding it in ancient sedimentary rocks suggests that Mars once had a thick atmosphere full of carbon dioxide. This gas is important because it traps heat, much like it does on Earth, allowing for liquid water to exist on the surface.

Scientists have long thought that features like dry riverbeds and lakebeds on Mars show that water once flowed across its surface. But until now, there was little direct evidence showing that Mars had enough carbon dioxide in its past atmosphere to support such a climate.

According to Benjamin Tutolo, a geochemist at the University of Calgary and lead author of the new study, this discovery helps answer an old mystery: if Mars had enough carbon dioxide to keep it warm, why haven’t we found more carbonate minerals like siderite before?

The rover’s samples showed up to 10.5% siderite by weight, providing strong support for the idea that a lot of Mars’ past carbon dioxide ended up locked in rocks through natural chemical processes.

Similar rocks have been spotted across Mars, so scientists believe this hidden carbon storage might be widespread. That could explain what happened to the carbon dioxide that once warmed the planet.

These rocks are around 3.5 billion years old, formed during a time when Gale Crater likely had a lake and before Mars became the cold, dry world it is today.

Edwin Kite, a planetary scientist involved in the study, called Mars’ shift from habitable to barren the planet’s “biggest known environmental disaster.” He said we still don’t know exactly why the change happened, but this new discovery is an important clue.

On Earth, the carbon cycle is balanced through processes like volcanic eruptions and plate tectonics, which recycle carbon dioxide. Mars doesn’t have plate tectonics, so once carbon dioxide got trapped in rocks, it likely stayed there.

The scientists say that Mars’ ancient carbon cycle was one-sided—more carbon dioxide got buried than released—helping explain how the planet lost its ability to support life.

This discovery not only adds to our understanding of Mars’ history, but also helps scientists update models of the Martian climate and its chances of once having been a habitable world.

Highlights:

NASA’s Curiosity rover discovered siderite, revealing Mars once had a carbon-rich, warmer atmosphere.
The find supports the idea that liquid water once existed on Mars, possibly making it habitable.
Up to 10.5% siderite was found in Gale Crater rocks, helping explain where Mars’ carbon dioxide went.
The discovery offers a major clue in solving how Mars lost its ability to support life over time.