How did Mars turn from a wet planet to a frozen desert?

Today, it seems that Mars has become Desert cold and dry; But about 3.5 billion years ago – or a little more – it is ambiance It was hot enough for liquid water to flow across the planet’s surface. In 1972, it was the Mariner 9 mission that first revealed landscapes on Mars studded with ancient river basins. For decades, researchers have amassed evidence to support this. However, they still did not know the reason for this shift.

It is generally agreed that the depletion of the Martian atmosphere in Carbon Dioxide (Ko₂) has caused this amazing drying of red planet. but, University of Chicago researchers (USA) suggests that the transition from a hot, humid planet to a cold, dry planet could be the result of the loss of another component of the atmosphere. Which ? The question remains.

Researchers studied thousands of photos returned by many Missions launched to Mars In the last years. They analyzed how river courses overlap and how they are altered. All to reconstruct the history of the Red Planet River over the past billions of years. With the idea of ​​combining these analyzes and simulations of climatic conditions. To determine what best corresponds to observations made by instruments that have flown over Mars.

A better target for habitable planets

In the process, the researchers realized a change in the amount of carbon dioxide₂ – a strong greenhouse gases, we only know well – in the atmosphere of Mars the climatic conditions of the red planet have not changed sufficiently. In other words, CO₂ It does not appear to be the main driver of the wet/dry transition that occurred on Mars. Another major factor could have intervened. He added, “We do not know what this factor is, but it must be present in large quantities to explain the results.” »says Edwin Kite, a geophysicist at the University of Chicago, in A communication.

There seem to be several alternative solutions. The first is the one proposed by the same researchers last year. having a layer of Clouds Thin and icy high in Mars’ atmosphere that would trap heat. Other scientists have suggested that hydrogen released from the planet’s interior may have reacted once with carbon dioxide₂ into the atmosphere to absorb infrared light and heating the planet.

The perseverance rover, which is currently roaming the Earth of the Red Planet, could provide additional evidence that would at least help eliminate certain hypotheses. As researchers know, for a planet, maintaining stable – and life-friendly – conditions for millions or even billions of years is no easy feat. Solving the mystery of Mars’ drying up could eventually allow them to target potentially better habitable exoplanets.