According to the researchers, ancient water trickling through Mars' rocks could have triggered a series of chemical reactions, converting CO2 into methane and trapping the carbon

Mars’ Early Thick Atmosphere Could Be Locked Up in the Planet’s Clay Surface Researchers from MIT suggest that Mars' once thick atmosphere may be trapped within the planet's vast clay deposits, potentially storing significant amounts of carbon dioxide as methane.

Two MIT geologists believe they’ve found the answer in Mars’ clay-covered crust. Interestingly, the study estimates that Martian clay could store up to 80% of the planet’s i