Mars is the first American visitor for years, a three-legged geologist

Mars is about to attract its first American visitor for years: a geologist with three legs and an arm to dig deep and listen to earthquakes.

NASA's InSight enters the Martian sky on Monday after a six-month, 300-million kilometer (480 million kilometer) trip. It will be the first US spacecraft to land since the Curiosity rover in 2012 and the first dedicated to underground exploration.

NASA uses a proven method to bring this mechanical miner to the surface of the red planet. The engine shots will slow down his final descent and the probe will land on his rigid legs, imitating the landings of previous successful missions.

This is where the old school of this billion-dollar effort led by the United States and Europe ends.

Once California flight controllers have determined that the coast is unobstructed at the landing site – relatively flat and unobstructed – InSight's 1.8 m (6 ft) arm will pull off the two experiments. Major scientists from the lander's bridge and will place them directly on the Martian surface. .

No spaceship has tried such a thing before.

The first ones do not stop there.

An experiment will attempt to penetrate Mars on 5 feet using a self-hammering nail equipped with heat sensors to measure the internal temperature of the planet. This would break the extraordinary depth record of 2 and a half feet (2.5 meters) drilled by the Apollo Moonwalkers nearly half a century ago for lunar heat measurements.

Astronauts have also left instruments to measure moonquakes. InSight offers the first seismometers to monitor marsquakes, if they exist. Still another experiment will calculate Mars' wobble, providing clues to the planet's core.

He will not look for signs of life, past or present. No life detector is on board.

The spacecraft is like an autonomous robot, said lead researcher Bruce Banerdt of NASA's Jet Propulsion Laboratory.

"He has his own brain, he has an arm capable of manipulating things, he can listen with his seismometer, he can sense things with pressure sensors and temperature sensors, he draws his own energy from the sun." he declared. .

By exploring the interior of Mars, scientists could learn how our neighbor, as well as other rocky worlds, including the Earth and the Moon, have formed and transformed over billions of years . Mars is much less geologically active than the Earth and its interior is closer to its original state, an enticing time capsule.

InSight aims to "revolutionize our vision of the inside of the planet," said Thomas Zurbuchen, head of NASA's science mission.

But first, the 360-kilogram vehicle must reach the Martian surface safely. This time there will be no bouncing balloon with the spaceship inside, as there was for the Spirit and Opportunity rovers in 2004. And there will not be any Celestial crane to lower the LG like there was for the six wheeled Curiosity during its dramatic "seven minutes of terror".

"It was crazy," acknowledged InSight project director Tom Hoffman. But he noted: "Every time you try to land on Mars, it's crazy, frankly, I do not think there's a healthy way to do it."

No matter how it is done, arriving on Mars and landing there is difficult – and ruthless.

The success rate of the Earth on Mars is only 40%. This includes planetary flyovers dating back to the early 1960s, as well as orbits and landing gear.

Although it had its share of flops, the United States has by far the best record. No one else managed to land and operate a spacecraft on Mars. Two years ago, a European lander entered so quickly, his descent system being uncertain, that he dug a crater during the impact.

This time, NASA borrowed a page from the twin Vikings of 1976 and Phoenix 2008, which were also stationary and three-legged.

"But you never know what Mars is going to do," said Hoffman. "It's not because we've done it before that we're not nervous and looking forward to doing it again."

Gusts of wind could cause a dangerous fall of the spacecraft during the descent, or the parachute could entangle. A dust storm like the one that hit Mars last summer could hamper InSight 's ability to generate solar energy. One leg could get buckled. The arm could get stuck.

The most tense time for flight controllers in Pasadena, California: the six minutes following the moment the spacecraft hits the atmosphere and touchdown of Mars. They will have peanut pots on hand – a tradition of good fortune that goes back to the successful Ranger 7 mission on the moon in 1964.

InSight will enter the Mars atmosphere at a supersonic speed of 12,000 km / h (19,800 km / h), based on its white nylon parachute and a series of engine shots designed to slow down enough to allow a landing. smoothly on Elysium Planitia, a vast equatorial plain of Mars.

Hoffman hopes it is "like a Walmart car park in Kansas".

The flatter, the better it will be so that the undercarriage does not rock, ending the mission, and so that the robotic arm can pose the scientific instruments.

InSight – abbreviation for indoor exploration using seismic surveys, geodesy and heat transport – will rest near the ground, the upper deck one meter or less above the surface. Once its two circular solar panels open, the undercarriage will occupy the space of a large car.

If NASA is lucky, two suitcase-sized satellites followed by InSight since their joint takeoff in May could provide almost live updates when descending the LG. . There is an eight-minute lag in communications between Earth and Mars.

The experimental CubeSats, dubbed WALL-E and EVE from the 2008 animated film, will fly over Mars and will remain in perpetual orbit around the sun, their technological demonstration over.

If WALL-E and EVE are dumb, the landing news will come from NASA's orbiters on Mars, but not as quickly.

The first images of the landing site should start flowing shortly after touchdown. It will take at least 10 weeks before scientific instruments are deployed. Add a few more weeks for the thermal probe to bury itself in Mars.

The mission is designed to last a full Martian year, the equivalent of two Earth years.

As the landing day is so close to Thanksgiving, many flight inspectors will be eating turkey at their desks during the holidays.

Hoffman expects his team to wait until Monday to fully thank them.

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