The question of where Mars’ atmosphere disappeared to has long been one of the central mysteries in the planet’s 4.6-billion-year history.
However, two geologists from MIT may have found an answer, one that lies within the soil of the Red Planet. In a paper published in *Science Advances*, the researchers suggest that much of Mars’ lost atmosphere may be trapped in a layer of soil covering the planet.
The report posits that when water once existed on Mars, it could have slowly seeped through specific types of rocks. This process gradually extracted carbon dioxide from the atmosphere and converted it into methane, a form of carbon that could remain stored in the Martian soil almost indefinitely.
Similar processes can be observed in certain regions of Earth. The researchers applied their knowledge of the interactions between rocks and gases on Earth to Mars, hypothesizing that similar processes might have taken place on the neighboring planet.
By estimating the amount of soil covering Mars’ surface, they calculated that the Martian soil could hold up to 1.7 bars of carbon dioxide—bar being a unit used to measure pressure.
