Japan brings in alien particles from a rock 300 million kilometres from Earth

Japan has completed its most ambitious space mission in the last decade. The Japanese Aerospace Exploration Agency (JAXA) has succeeded in bringing to Earth grains from the ground of an asteroid, a space rock orbiting our planet and Mars.

On Sunday, December 6, at 19:07 Spanish peninsular time, a very small 16-kilogram armoured capsule with about 100 milligrams of small soil fragments from the asteroid catalogued 162173 Ryugu entered the Earth's atmosphere at high speed. It descended the last 10 kilometres supported by a parachute and landed at the Woomera Projectile Experiment Complex, a limited area of about 100 square kilometres located in the extreme south of Australia, about 500 kilometres northwest of the city of Adelaide.

As described above, the spacecraft Hayabusa2, the Peregrine Falcon - has ended its high-risk exploratory mission by encountering the rock, which is about 500 metres in diameter, as it spins on itself while moving at speeds of around 100,000 kilometres per hour. A space relic believed to be around 4.6 billion years old, the journey there and back has taken six years, as it is located 300 million kilometres from our Blue Planet.

To more easily locate the exact location of the impact on Australian soil, the JAXA has used telescopes to observe the light emitted by the capsule during its entry into the atmosphere. It had also organized an extensive deployment of detection instruments on board helicopters and drones, as well as antennas located around the large planned landing area. "He is finally back home", exclaimed the head of the mission, Professor Yuichi Tsuda.

A charter flight awaited the hermetically sealed container to be immediately transported to Japan to begin the distribution and analysis of the alien rock sediments as soon as possible. Rich in water and organic carbon compounds and no larger than 2 centimetres in size, Japanese scientists intend to try and decipher the origin of the solar system and the asteroids, since their surface, unlike that of the planets, has remained practically unchanged.

With Beijing pushing hard with the Chang'e missions to the moon, Tokyo put the 610-kilogram Hayabusa2 probe into orbit on 3 December 2014, reaching Ryugu on 28 June 2018 and spending a year and a half around the small space rock. Once in its vicinity, the probe had to approach very slowly to avoid hitting its irregular surface and causing the mission to fail.

At the end of September of that year, it deposited two tiny 1.1 kg all-terrain vehicles and a 9.6 kg surface module, all packed with instruments. Hayabusa2 landed on the asteroid on 22 February 2019 to catch samples of Ryugu's surface layers. The operation lasted a few seconds and at a very well calculated speed, and immediately afterwards it moved away at full speed, all in a completely autonomous manner.

A few months later he fired a small explosive charge to cause fragments to fall. Once the area where the explosion debris fell was stable, the probe descended again on 11 July, this time into the crater formed. It collected particles of the material ejected by the detonation and, having done its job, at the end of 2019 began the journey back to Earth.

The mission that has just concluded is part of a larger JAXA project to collect materials from nearby asteroids and bring them back to Earth for analysis. The first stage was Hayabusa, which took off from the Japanese Space Centre in Tanegashima on 9 May 2003 and returned on 13 June 2010. Its aim was to reach asteroid 25143 Itokawa, a body located 300 million kilometres from the Earth and orbiting around the Sun, also between the Earth and the Red Planet.

Very irregular in shape, rocky, elongated (530 metres long) and described as very similar to a large flying potato, Hayabusa was the first initiative to attempt to bring samples of a celestial body other than the Moon. The first Hayabusa reached the vicinity of the small flying rock on 12 September 2005. She studied it for several months from 20 to 7 kilometres and then landed on its surface on 20 November for half an hour.

It took off, kept circling the asteroid and five days later it descended again at another point to stay for a few seconds while it trapped to bring them back to Earth. The mission was not a complete success as Hayabusa released a small surface module named Minerva to take pictures and measure its temperature, but failed in the attempt.

Research on the 1,500 particles between 3 and 180 microns in size captured by Hayabusa and published in the journals Science Advances and Science has confirmed that the rocky asteroid Itokawa contains large amounts of water. Also, that the most frequent meteorites that reach the Earth - called chondrites -, come from similar space rocks and are mostly composed of silicon.

The collection of asteroid samples is also the subject of interest from the community of US scientists committed to the knowledge of outer space. The first NASA spacecraft dedicated exclusively to studying one of these heavenly bodies is OSIRIS-REx, a 2,110-kilogram probe that was launched into space on 8 September 2016 to travel to the encounter with the small asteroid 101955 Bennu.

With the shape of a giant rounded stone 490 meters in diameter and in orbit 330,000 kilometres from the Earth, OSIRIS-REx descended on Bennu on October 20th. It deployed its 3.35 metre articulated robotic arm with a sort of hoover at its end and collected organic sediments from the soil for 10 seconds.

OSIRIS-REx is now circling the asteroid, until March 2021 when NASA technicians decide to start its return home. If the schedule is met, it is expected to land in the Utah desert on 24 September 2023 with a maximum of 2 kilos of samples from Bennu. The NASA Deep Space Network, one of whose three monitoring stations is located in Robledo de Chavela (Madrid), has followed the two Japanese missions and now OSIRIS-REx.