The Perseverance rover begins its exploration of the planet Mars


At the end of a perilous re-entry into the atmosphere of the Red Planet, the NASA probe made an ideal landing, on a site conducive to the search for possible traces of life.

At 9:55 p.m. French time on Thursday evening, Swati Mohan, the engineer in charge of flight operations, had a brief moment of hesitation. Then she finally said with obvious relief the two long-awaited words: “Confirmed landing”. Perseverance, NASA’s new six-wheeled, $ 2.4 billion rover is on Mars. Eruption of joy in the control room of the Jet Propulsion Laboratory of Nasa (JPL) in California, where, Covid obliges, simple “checks”, fist against fist, replace the usual braces, these “hugs” so dear to Americans.

At the end of a perilous re-entry into the atmosphere of Mars at nearly 20,000 km / h, the American probe perfectly carried out the sequence of seven minutes of critical operations necessary to place on Martian soil the precious rover of a ton… in one piece. “The JPL teams have once again shown that they are the best in the world for this kind of maneuver, it’s really impressive”, applauded Sylvestre Maurice, astrophysicist at Irap and father of the SuperCam instrument on board the mast of the American robot.

During the landing phase, the scientist was at the headquarters of Cnes, the French space agency, to explain live to Emmanuel Macron and his wife the progress of operations. Because if the success of the landing is 100% American, France can be proud of having designed and manufactured an emblematic part of the rover, its “eye”, capable of studying rocks several meters away thanks to its five high-precision instruments, including a powerful laser.

Somewhat blurry images

The first images sent back to Earth and broadcast Thursday evening by NASA, are in black and white and slightly blurry because of the transparent covers that still protected the cameras. If they will not win beauty prizes, they do show that the automatic guidance system during the descent has fulfilled its role perfectly. The terrain is perfectly flat, almost boring, dusty, and strewn with a few lighter pebbles. “We’re just one kilometer from the center of the landing ellipse. So we start the mission there we wanted ”, rejoices Nicolas Mangold, geologist specializing in Mars at the Planetology and Geodynamics Laboratory in Nantes and member of the mission. “The site is very flat, with mostly sand, but we are right in the middle of two very interesting fields that will keep us busy for several months. To the east, fractured rocks with a little less sand, and to the west, paler, rougher terrain. ”

We are just two kilometers as the crow flies from our first main target, the edges of the delta where we will look for sedimentary strata

Nicolas mangold

The six wheels of the rover therefore rest as expected on the bottom of the Jezero crater, a large circular structure 45 km in diameter created by a gigantic impact. The site was chosen because about 3.5 billion years ago, at a time when the planet was hotter and wetter than today, a river flowed into the crater, carving a canyon and depositing a range of sediments. The water has long since disappeared, but the presence of this river delta on the edge of the crater makes it a particularly interesting site for looking for possible traces of life, one of the main objectives of the mission. “We are just two kilometers as the crow flies from our first main target, the edges of the delta where we will look for sedimentary strata», Specifies Nicolas Mangold.

For a geologist, this stack of layers of sediment is the ideal environment to retrace the history of the site, and to “read” the way in which the water has affected the environment there, perhaps giving favorable conditions to the site. life. “With the Performance auto-navigation system, more efficient than Curiosity, we can do more than 100 meters per day on favorable ground, specifies the Nantes researcher. At this rate, the delta really won’t be far. “But before you start riding and doing science, you must first check that everything is working well on board», Specifies Sylvestre Maurice, who is impatiently awaiting the deployment of the mast on which his SuperCam instrument is installed, normally on Friday.

A verification period of thirty Martian days

Because of the incredible complexity of Perseverance, 1026 kg of high-tech mechanics and advanced electronics, this verification period is going to be long, and must last at least thirty days. Or rather 30 Martian days, each lasting 24 hours and 39 minutes. A slight delay which forces the two French scientists, like their American colleagues, to fix their agendas on Martian time, and to start their work 40 minutes later each day.

There remains the problem of the Covid, not easy to manage for such a complex mission which requires the collaboration of more than 250 scientists spread around the world. “In a way, my office is on Mars, 200 million miles away, but we miss direct interactions with our American colleagues, I must say», Regrets Sylvestre Maurice.

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