Mars’s ancient atmosphere might be locked in clay

They believe that while water exists on Mars, the liquid may have flowed through certain types of rocks, triggering a slow series of reactions that gradually sucked carbon dioxide out of the atmosphere and converted it into methane, a form of fuel that can be stored form of carbon in clay for eons.

The researchers applied their knowledge of the interactions between rocks and gases on Earth to how similar processes could occur on Mars. They found that the amount of clay covering the surface of Mars could hold up to 1.7 bars of carbon dioxide₂equivalent to about 80% of the Earth’s early atmosphere. “In some ways, Mars’ missing atmosphere may be hiding in plain sight,” Murray said.

Researchers believe that this sequestered carbon may one day be recycled and converted into propellant to fuel future missions between Mars and Earth.