A Japanese spacecraft lands successfully on an asteroid and recovers a dust sample

At about 200 million kilometers from Earth, a Japanese spacecraft has just recovered a tiny sample of earth on the surface of an asteroid – the second time that humanity has achieved such a feat. The precious samples are intended to return to Earth, where they will be analyzed by scientists. This review could tell us a lot about the chemical composition of these rocks, as well as the materials present in the early days of the solar system.

Hayabusa-2, operated by the Japan Aerospace Exploration Agency (JAXA), is the spaceship in possession of this newly acquired asteroid. This is the successor to the original Hayabusa mission of the JAXA, which was the first to return samples of an asteroid to Earth in 2010. Launched in 2014, Hayabusa-2 has traveled in the US. space for three and a half years and arrived at an asteroid named Ryugu in June 2018. Since then, Hayabusa-2 drags around Ryugu, analyzing the surface and applies to the large sample collection of today hui.

Late last night, the spacecraft fired its engine, causing the vehicle to slowly descend to the surface of Ryugu. Then, when Hayabusa was hovering just above the asteroid, he tapped a horn-shaped appendage on the ground. As soon as this happened, a bullet-like projectile in the horn shot outward, stabbing the asteroid and creating a pile of dust and fragments. If all goes well, some of these fragments are fed up in the horn and gathered in a small room inside the spacecraft.

Hayabusa-2 will retain this material until he leaves Ryugu and returns to Earth. And when these samples arrive on our planet, they could tell us a little more about what was our cosmic neighborhood billions of years ago. "From a scientific point of view, this goes back to the dawn of the solar system," said Dante Lauretta, principal investigator of NASA's Asteroid Specimen Return Mission, OSIRIS-REx, who worked with the Hayabusa-2 team. The edge. "These asteroids are the first rocks that have formed around the Sun before the planets exist."

Hayabusa-2 hopes to bring back between 10 and 100 milligrams for study. However, it is not known exactly how much material sample the spacecraft has picked up. JAXA has no way of measuring the amount of material collected by Hayabusa-2. However, the agency says that each maneuver went as planned and that Hayabusa-2 gave the order to shoot his bullet as planned. This makes them almost certain that the spacecraft has some samples in his belly.

Image: JAXA

In fact, the original Hayabusa was still able to get a sample of his asteroid, Itokawa, even though his projectile had failed. In two touchdown attempts, the data showed that the bullet firing mechanism was not working. However, some dust still accumulated in the sample collector when Hayabusa touched the Itokawa surface. "If they manage to get in touch with the asteroid, something will come up in the measuring chamber," says Lauretta.

Nevertheless, sampling samples from an asteroid is an extremely difficult process. This requires pinpoint accuracy around an object where gravity is very low. This means that minimal forces, such as the pressure of solar radiation or gases from the spacecraft, can have a significant effect and deflect the vehicle. "When you find yourself in these microgravity environments around small asteroids, [small forces] kind of pushing you substantially, "says Lauretta.

To ensure the best possible sample capture, the JAXA performed multiple dress rehearsals during which she lowered the satellite very close to the location on Ryugu where the team wanted to take a sample . Hayabusa-2 even deployed two tiny rovers on the surface of the asteroid in September, in order to collect data on its environment. The Ryugu pitch proved to be much rockier than the JAXA imagined. The mission team therefore decided to do additional tests to make sure everything would still work. The abundance of caution involved postponing the date of sampling scheduled from October to today.

Image: JAXA

Now that Hayabusa-2 has recovered his sample, it is possible that he will get another one in the months to come. The probe essentially carries a small gun that it can use to strike Ryugu's surface, exposing the rocks deeper into the asteroid. Hayabusa-2 could then lower and take another sample from this crater. However, the JAXA experts have not yet decided if this would actually happen. Hayabusa-2 is expected to leave Ryugu a little later this year.

In the meantime, today's success could be used to make Lauretta's mission, OSIRIS-REx, a success. NASA's OSIRIS-REx space probe was launched in September 2016 and arrived on the asteroid Bennu at the end of last year. OSIRIS-REx will also take a Bennu sample over the next year, although it uses a very different instrument than the one used by Hayabusa-2. Rather than shooting the asteroid with a projectile, OSIRIS-REx will blow a highly pressurized gas at Bennu's surface, which hopefully will bounce the rocks into a collector plate.

The OSIRIS-REx mission team will do a thorough preparation, but it still does not know exactly what the touching of the asteroid will be like. "What's the answer to this surface?" Asks Lauretta. "This is the biggest uncertainty we have tried to model." Lauretta hopes the Hayabusa-2 team can tell us more.

If all goes well, it means that two samples of different asteroids will be brought back to Earth in the coming years. And these pieces could contain clues about the early history of the solar system and even about our own planet. Scientists believe that some of the oldest building blocks of life – such as carbon, hydrogen and other organic matter – could have come to Earth under ancient asteroids. Finding this material on the rocks surrounding our solar system could mean that life is possible in other worlds nearby.

"The probability that there is life on the basement of Mars, or on the oceans of Europe or Titan, becomes much higher," says Lauretta, "if basic chemistry was ubiquitous in the early solar system and was not peculiar to the Earth "