A selfie from the Curiosity rover on Mars.

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NASA / JPL-Caltech / MSSS

  • For eight years, the Curiosity rover has explored the red planet to try to understand why it has become an uninhabitable arid place.

  • Thanks to a telescope, scientists have just observed a geological transition more closely.

  • This provides key information on the drying up of Mars, which took place in several stages.

    A clue on the planet's climate change that still has a lot of secrets to deliver.

Millions of kilometers from Earth, since February, all eyes have been on Mars and the first steps of Perseverance.

But while NASA's new rover deploys its instruments in the heart of Jezero Crater, further southwest, Curiosity continues to carve out its route on Mount Sharp.

And his daily work delivers, more than eight years after his arrival, still precious secrets on the red planet.

Latest: Mars did not dry up suddenly 3.5 billion years ago, but over a period of several thousand years.

This discovery is due to a team of Franco-American researchers who have just published an article in the magazine Geology.

From orbit, these specialists had already spotted a geological transition on part of the mountain.

Fluctuations in wet and dry periods

But it took time to get close.

“It's a mountain that is almost 6 km high, difficult to explore because we are in canyons, outcrops everywhere.

We knew that this sedimentary transition was important but we did not really know its nature.

From orbit, we could see that there were clays at the sedimentary base and, above, sulphates.

But we absolutely did not know what was behind that, ”explains William Rapin, CNRS researcher at the Institute for Research in Astrophysics and Planetology (IRAP) in Toulouse.

Thanks to the ChemCam instrument, and its telescope with a much higher resolving power than other cameras, they were able to observe this phenomenon up close and for the first time to see the details.

And the result amazed the research team.

“For eight years, we have seen dried sludge, sands deposited by ancient rivers and there, suddenly, we arrive in the sulphates.

The surprise is that higher up, we again have deposits, the nature of the structures that we see with the telescope changes and again we are in a humid environment, probably a river flood plain.

This allows us to confirm for the first time on Mars that a mineral change is associated with a change in climate, we can suspect elsewhere on Mars that these sulphates are linked to climate change, ”emphasizes the scientist.

For now, the origin of these fluctuations remains a mystery.

But that's what motivates those who have their eyes on Mars.

Curiosity will continue to climb this mountain and drill, to find out the chemical composition of these great seas of sand.

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  • Geology

  • Perseverance

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  • Curiosity

  • Toulouse

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