New research suggests Mars’ atmosphere may be hidden in its clays, absorbed by minerals over 3 billion years ago, explaining its transformation from a potentially life-supporting planet. NASA’s rovers have found evidence of ancient water, implying Mars once had an atmosphere to prevent freezing. Researchers propose that water triggered reactions in rocks, converting atmospheric CO2 into methane, which was then sequestered in clays. This process, similar to Earth’s, could mean methane remains on Mars, potentially usable as an energy source. The study, led by MIT’s Oliver Jagoutz, focused on smectite clay’s carbon-trapping efficiency.