Comment Curiosity a révolutionné nos connaissances sur la planète Mars

Comment Curiosity a révolutionné nos connaissances sur la planète Mars

On August 6, 2012, after a seven-minute descent where NASA engineers clung to their chairs, Curiosity rover rested its wheels in a crater on Martian soil. The beginning of an adventure that is supposed to last two years and that, a decade later, continues to excite scientists every morning that they receive the news and images collected by this jewel of technology weighing almost 900 kg. Especially those behind the screens of the French Operations Center for Science and Exploration at the Toulouse Space Center.

For ten years, CNES engineers and researchers from the Pink City Astrophysics and Planetology Research Institute have been scrutinizing the results of the laser shots that they programmed in the ChemCam instrument the day before, millions of kilometers from the floor of the cows. Since its arrival on the red planet, after having traveled 28.4 km, the rover has not been idle, pointing 907,000 times at the rock that surrounds it.

The habitability of Mars is proven

Not for the pleasure of degumming sediments, but to fulfill the objectives of the Mars Science Laboratory exploration mission, launched in 2003, by observing their chemical composition using a spectrometer. “Earth and Mars formed at the same time but evolved differently. We want to know why Mars became what it is. It is also a way to better understand the Earth, to study the origin of life, but also the Martian climate and, why not, prepare for the next human exploration”, recalls Valérie Mousset, director of the Curiosity project at CNES.

A mission that Curiosity has already fulfilled to a large extent since it has shown “that Mars in the past could have been habitable more than 3,000 million years ago in a simple life form,” continues the manager. Curiosity thus found traces of water, chemical and energetic compounds necessary for microbiological life, and traces of organic molecules.

“Thanks to all these measurements we were able to make a chemical map. Therefore, we are interested in small transformations over time, how many times the rocks have been in contact with water, but also to observe how the wind has shaped them”, continues Olivier Gasnault, head of the ChemCam instrument and researcher at the IRAP. Like this fascinating image of a 1 cm sand rose, a tiny concretion eroded by sedimentary rock that has been cemented by mineral-rich groundwater.

The teams have shown that the Red Planet has experienced alternating dry and wet periods, before drying out completely nearly 3 billion years ago.

Discovering a huge valley

Thanks to its drill and excavator, Curiosity was also able to collect soil samples and analyze them. Finding low-level methane, clay, chlorinated salts, perchlorate and “among the latest important discoveries, we recently found sulfur compounds,” says Arnaud Buch, a CNRS engineer in the laboratory for space, environmental and atmospheric observations.

Despite heavily worn wheels and extreme temperature conditions, the rover will continue to roll down its hump for another three years. In fact, NASA has committed to funding the mission’s operation and research through 2025. And, while more than 3,000 km away, its successor Perseverance continues to survey the Martian soil surface and collect samples, Curiosity is now entering to a valley 800 m wide. and 100 m high. “At the bottom of the valley, there is like a river bed that could be the last water flows on Mars. The large scree scattered on the ground will also allow us to see what is above”, enthuses Olivier Gasnault. The adventure is far from over.

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