Recent research poses an intriguing question about Mars: could the planet's lost atmosphere be "hiding in plain sight"? An innovative study suggests that the once-abundant atmosphere of the Red Planet may have been absorbed by minerals in its clay-rich surface, leading to the dramatic transformation of Mars into the dry desert we see today. This finding not only reshapes our understanding of Martian history but also raises the possibility of past life on our neighboring planet.

For millions of years, Mars was not the barren world depicted by the rovers Perseverance and Curiosity. These two NASA explorers have unearthed compelling evidence of liquid water flowing over the Martian surface billions of years ago, indicating that the planet must have had a thick atmosphere to prevent that water from freezing. The burning question that has puzzled scientists for decades remains: Where did that atmosphere go?

Researchers from the Massachusetts Institute of Technology (MIT) suggest that the answer might lie in the planet's clays. In a paper recently published in *Science Advances*, the team argues that as water permeated Martian rock types, chemical reactions took place that captured carbon dioxide from the atmosphere. This carbon dioxide was possibly converted into methane and subsequently trapped within the clays.

"This process could mean that significant amounts of carbon dioxide were sequestered in clays, similar to what we observe on Earth," says Oliver Jagoutz, a professor of geology at MIT. "It's even conceivable that this methane could still exist, potentially serving as an energy resource for future Mars missions."

Originally, the research centered around Earth and its geology. The scientists investigated how processes like tectonic plate movement influence the structure of Earth's crust—the lithosphere. They focused on a specific clay mineral, "smectite," renowned for its ability to trap carbon. A single grain of smectite has numerous folds that permit carbon to remain locked away for billions of years.

On Earth, smectites form through the weathering of tectonic plates, drawing carbon dioxide from the atmosphere over time. However, given Mars' lack of tectonic activity, scientists pondered how similar smectites could arise on the Red Planet. The answer may lie in certain igneous rocks known as “ultramafic rocks,” which have low silica content but can also create smectites when exposed to water.

The research team utilized a model that simulated water's interaction with these ultramafic rocks, proposing that over a billion years, water could have seeped into the Martian crust, reacting with olivine—a magnesium-iron silicate mineral. As olivine oxidized, it released hydrogen, which could have combined with carbon dioxide to create the trapped methane.

Their findings revealed that to sequester significant levels of carbon dioxide, Mars would need layers of smectite at least 3,600 feet (1,100 meters) deep. The presence of these clay deposits gives credence to the theory that much of Mars' original atmosphere was absorbed over time, leading to its current inhospitable conditions.

The implications of this research extend beyond mere Martian geology. Understanding how Earth's atmosphere evolved in comparison to Mars could have significant consequences for the search for extraterrestrial life and for potential human colonization of the Red Planet. Future missions will likely focus on investigating these clay deposits more closely, potentially exploring the remnants of Mars' atmosphere that may still be locked away in its crust.

In conclusion, as scientists delve deeper into Mars' mysterious past, they may unravel the secrets surrounding its lost atmosphere—possibly even uncovering a scenario where, more than three billion years ago, the Martian landscape transitioned from a life-supporting environment to the stark wasteland we study today. Who knows? The stories concealed within Mars' soils could rewrite our understanding of life’s potential beyond Earth!