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The US space agency’s Perseverance rover is only three weeks away from its arrival on Mars.
The robot’s current distance from the Red Planet is still around 4.5 million km (3 million miles), but this gap is closing at a rapid rate.
The largest and most sophisticated vehicle ever sent to land on another planet, the NASA robot is targeted on a near-equatorial crater called Jezero.
Touchdown is expected shortly before 9:00 p.m. GMT on Thursday, February 18.
To descend, NASA’s rover will have to survive what engineers call the “seven minutes of terror” – the time it takes to get from the top of the atmosphere to the surface.
“Terror” is a reference to the daunting challenge that is inherent in trying to reduce an input speed of 20,000 km / h to something like the pace of walking when “riding”.
“When scientists look at our landing site, Jezero Crater, they see the scientific promise of everything: the remains of an ancient river going in and out of this crater and thinking that’s the place to go for it. look for signs of past life. But when I look at Jezero I see the danger, ”says Allen Chen, the engineer who leads the entry, descent and landing (EDL) effort for Perseverance.
“There is danger everywhere. There is this 60-80m high cliff that cuts through the middle of our landing site. If you look west, there are craters that the rover cannot. get out even if we manage to land. in one of them. And if you look east there are some big boulders that our rover would be very unhappy about if we dropped them, “he said. at BBC News.
Fortunately, Perseverance has proven technologies that should ensure it reaches a safe point on the surface. Among them is the famous “Skycrane” jet pack which managed to land NASA’s previous rover, Curiosity, eight years ago.
There are even a few additions designed to improve reliability. The parachute system that slows atmospheric descent from supra to subsonic speeds now has something called a “range trigger”. This more precisely times the opening of the parachute to bring the rover closer to its fictitious target.
Unlike Curiosity which has just opened the chute when it reaches a predetermined speed, Perseverance first checks its surroundings before issuing the command.
Related to this is terrain navigation. Perseverance will examine the ground below and check it against satellite imagery of the crater to better assess its position.
It’s like you or I are looking out our car window and then looking at a map to see where we’re at, Chen said.
“This is what we are asking Perseverance to do on its own, find out where it is, and then fly to known safe places nearby.
Curiosity managed to land about a mile from the dummy target. He slightly exceeded. Perseverance, with its improved landing technologies, should do a lot better.
Scientists have already named the area that includes the target. It is called Timanfaya, named after the Spanish national park of Lanzarote, one of the Canary Islands.
Lanzarote Timanfaya is volcanic terrain; the Martian version, which encompasses a square of 1.2 km by 1.2 km, probably also contains volcanic rock. This is the floor of the Jezero crater.
Although this is the landing spot, it is not the main interest of the mission. It’s the remaining delta just to the north, with more distant carbonate rocks that researchers say could trace the edge of a once-huge lake in Jezero.
“Carbonate rock is extremely abundant on Earth, but it’s quite rare on Mars and we don’t really know why,” says Ken Farley, the scientist for the NASA Project on Perseverance.
“There is an area at the edge of the crater that would have been the shore with a high concentration of carbonate. It is very attractive to us, because on Earth carbonate is often precipitated [by living organisms]: people will be familiar with things like coral reefs. And it’s a good way to record bio-signatures, ”he told BBC News.
The dream is that perseverance will stumble upon fossil evidence of stromatolites. These are sedimentary deposits that have been built up by layers, or mats, of microorganisms.
The structures and the chemistry they contain are recognizable to geologists. That said, we are talking about rocks in Jezero that are almost four billion years old.
The finds are unlikely to be of the slam-dunk genre, which is why Perseverance will pack their most interesting finds for later missions to be recovered and brought back to Earth for further study.
Farley says Perseverance will ask the most fundamental questions and the answers it produces will be instructive.
“Is it a case that if you build a habitable environment then life will come? Or is it like a magical spark that must also occur? And the answer to that question is really important, because we now know that there is has billions, literally billions of planets beyond Earth.
“What is the probability that life does not exist there? It seems small to me, but it all depends on the omnipresence of that spark that makes life come alive,” he explained.
Originally published
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