In search of the origins of life, the Japanese probe Hayabusa 2 lands on an asteroid

The Japanese spacecraft Hayabusa 2 has successfully landed on the surface of the asteroid Ryugu, a historical moment of space exploration that could provide fascinating details about the origins of life on Earth.

At 0749 local Japan time, the probe landed on Ryugu after descending from a stable orbit some 20 kilometers from the surface. Occurring some 310 million kilometers from the Earth – well beyond the point where even a flash communication is too slow for real-time control – the descent was automated and took about 23 hours. By gently touching the surface, the Hayabusa 2 spacecraft should have had a closing speed of only seven centimeters per second. If everything went as planned, a sampling arm several meters long was able to fire a bullet-like projectile into the surface, which resulted in a reduction of up to 0.1 gram of material. in a sample capsule and bring it back to Earth at the end of 2020.

The probe took images before, during and after the sample collection attempt, which will be the only way to know if the mechanism worked. After leaving the surface, Hayabusa 2 took about half a day to return to its original position above the asteroid. "It's really exciting, because it's the first time in history that we [may have] a sample of carbon asteroid, "said Patrick Michel of the Observatory of the Côte d'Azur in France, co-investigator of the mission.

Hayabusa 2 was launched in December 2014 by the Japan Aerospace Exploration Agency (JAXA) and arrived in June 2018 in Ryugu, a type C (carbon) primitive asteroid. Ryugu is barely a kilometer in diameter but contains a huge scientific treasure: immaculate materials left by the primordial solar system of 4.6 billion years ago, a time before the coalescence of the sequel of planets of the sun. To study this science-rich rock, Hayabusa 2 has already created global maps from his orbital pole and sent three small rovers to the surface in late 2018. A fourth rover will be deployed later this year. But the main objective of the mission has always been to collect samples directly from the surface, using equipment similar to that deployed during a previous mission, Hayabusa 1. Hayabusa 1, the only previous mission to return samples of asteroids, returned S-type (or stony asteroid) Itokawa dust grains in June 2010, a less-pristine object that would have formed much later than Ryugu in the history of the solar system.

The Hayabusa 1 sample collection mechanism, however, did not work as expected, as the projectile failed to fire the surface – even though the spacecraft's thrusters threw dust into the collector. The scientists and engineers of Hayabusa 2 hope to have solved the problem. If everything goes as planned, the benefits could be considerable. "This time, we think we can get some organic material," says Makoto Yoshikawa, JAXA's Hayabusa 2 Mission Manager, referring to carbon-rich compounds that, along with water and the sun, form the basis. fundamental of life on Earth. "In the case of Hayabusa 1 in Itokawa, we did not find any organic matter. But this time at the Ryugu asteroid, we think we can get organic matter and water in the sample. It is therefore our main goal. "

After the arrival of the spacecraft on the asteroid, the team began to study images to find a landing site conducive to the collection of a sample . It quickly became apparent that the material on the surface was not as fine as expected, but included rocks and rocks resembling ribbons that could easily escape an attempt at errant sample collection. So, to increase the chances of success, the probe dropped target markers on Ryugu in October 2018 – thin sheets of reflective material serving as mirrors for telemetry lasers capable of accurately measuring the distance to the surface .

Everyone, we did it !!! # haya2_TD

Thank you very much for your support around the world! pic.twitter.com/cHkeTCBgcs

– HAYABUSA2 @ JAXA (@ haya2e_jaxa) February 22, 2019

The initial plan included three separate landings and sample collections, returning material from different locations. Concerns about the rugged terrain, however, imply that only one other landing will likely be attempted, an even more ambitious goal. Not until April, the spacecraft will fire an impactor weighing one kilogram to the surface at a speed of two kilometers per second, digging a small crater two to three meters wide. The team will then decide whether to go down and try to collect a sample inside this crater, by picking up materials inside the asteroid itself, which has never been done before.

NASA scientists involved in OSIRIS-REx, another asteroid sampling effort taking place at the same time, will closely monitor Hayabusa 2's work in Ryugu. The OSIRIS-Rex mission plans to collect up to two kilograms of material from the asteroid Bennu, also a Type-C asteroid, by the end of 2020. A strong collaboration between Japan and the US has allowed both teams to share information, and OSIRIS The team will learn valuable data on Hayabusa 2's landing attempts. "We are very interested in what is going on during their sampling attempt," says Dante Lauretta, senior researcher on OSIRIS-REx and co-researcher on Hayabusa 2. "We're going to have a meeting. [with JAXA] go through the lessons learned. "

Looking back in time with remote sensing data and direct samples collected by this spacecraft, the researchers hope to understand how asteroids, and perhaps comets, have sown Earth from Earth first. Water and other ingredients essential to life. If and when the primitive samples of these primordial asteroids are rendered, global teams of scientists are looking for them to find organic materials such as amino acids, which could provide new clues to our early days. The analysis of the isotopic composition of the samples will also reveal the exact age of each asteroid, which will strengthen the chronology of the future of our solar system. "We want to check if these bodies contain organic materials," says Michel, "and analyze these materials to understand the role of asteroids in the emergence of life on Earth. One scenario could be that all the elements necessary for the emergence of life, including water and perhaps other prebiotic materials, were brought by these small bodies. "

Hayabusa 2 must leave Ryugu at the end of 2019 and by the end of 2020, he will arrive on Earth by putting his capsule filled with precious cargoes at the dawn of the solar system. With OSIRIS-REx, this intrepid interplanetary mission could tell us more about the origins of our world than ever before.

This article is reproduced with the permission of Scientific American. You can see the original story here.