Mars was not always as cold and dry as it is now. More and more facts show that billions of years ago, water currents flowed there. That is, a dense atmosphere was formed, which created a greenhouse effect and kept the water in liquid form. About 3.5 billion years ago, the water disappeared and the gas shell thinned significantly. Why? American geologists found that the answer lies literally on the surface.

Scientists from the Massachusetts Institute of Technology (USA) proposed to search for traces of the lost atmosphere in the clay minerals of the Martian crust. From the article published in the journal: Science DevelopmentsWater coming from the surface passes through rocks and starts a chain of chemical reactions that pull carbon dioxide from the atmosphere and convert it into methane. And this organic compound can be stored for long periods in clay minerals.

Similar processes are taking place in some parts of the world. Scientists have checked whether this is possible in the conditions of Mars. They determined how much clay there is on the planet. It turned out that its volume is enough to convert and retain 1.7 bar of carbon dioxide. This is about 80 percent of the planet’s initial atmosphere. It is possible that humanity will learn to extract this gas to produce fuel for future space missions.

“Using geological data, we have shown that similar processes probably occur on Mars. A certain amount of atmospheric CO₂ “It can go into methane synthesis and become clay. That methane could still be there. It’s the future energy source of the planet,” explained Professor of Geology Oliver Jagutz, one of the authors of the paper.

Jagutz and his colleague Joshua Murray studied the clay mineral smectite, which acts as an excellent carbon trap thanks to its layered structure. Gas hidden in the folds of a single smectite particle can be preserved for billions of years.

Scientists have shown that the mineral on Earth is formed as a result of tectonic activity. When it reaches the surface, it begins to release CO₂ It moves away from the atmosphere and retains it, causing cooling over millions of years.

The researchers’ next step was to map the Martian surface: They found it covered in smectite clays. Then they got the idea that it could serve as a carbon reservoir, like on Earth.

There are no signs of plate tectonics on Mars, at least not today. Where do you get smectite? Remote observations show that some areas of the Martian crust contain ultramafic igneous rocks. On Earth, their decomposition would lead to the formation of smectite. The same thing could have happened on the Red Planet when rivers with branching branches flowed through it.

To prove this, scientists modeled the reactions of ultrabasic rocks with water, as they do on Earth. They then added data from Martian igneous rocks, which are rich in the mineral olivine.

“We looked at the period when CO was on Mars₂ “It was everywhere, including the water seeping through the rocks,” Murray explained.

Over billions of years, water slowly reacted with olivine, which contained reduced iron. The oxygen in the water bound it, creating oxidized iron that gave the planet its red color. The hydrogen released combined with carbon dioxide in the water to form methane (CH).₄Over time, olivine was replaced by serpentine, which in turn became smectite.

It is estimated that the surface of Mars is covered in a layer of smectite clay that is 1,100 metres thick, enough to trap methane equivalent to most of the carbon dioxide lost from the atmosphere.