The fact that amino acids exist in other celestial bodies in the universe other than Earth is a topic of discussion. About 20 amino acids were discovered in the soil of the asteroid ‘Ryugu’. It was discovered in the soil of Ryugu, which was taken and brought to Earth by the unmanned space probe ‘Hayabusa 2’ of the Japan Aerospace Exploration Agency (JAXA). Amino acids are substances that make up life. Some scientists speculate that the asteroid impact may have brought the chemicals necessary for the birth of early life on Earth, or even brought life itself to Earth.
Supporting the hypothesis that ‘the origin of amino acids is the universe’
Hayabusa 2 is JAXA’s second asteroid probe after Hayabusa 1. The purpose is to discover the origins of mankind, water and life by exploring the asteroid Ryugu orbiting near Mars. It was launched into space in December 2014, the year after Hayabusa 1’s return. Ryugu is an asteroid discovered in May 1999. Hayabusa means ‘peregrine falcon’ in Japanese.
On June 27, 2018, Hayabusa 2 arrived in Ryugu orbit, which is 340 million km away. After that, 5.4 g of soil samples below the surface of Ryugu were collected twice in February and July 2019. Before collecting the sample, the probe first fired a 4.5 kg copper bullet at the asteroid at a speed of 2 km from about 500 m close to the asteroid. This is to make a small explosion happen the moment a bullet hits the surface, to remove the surface material and other foreign substances, and to obtain the soil under the resulting pit. The purpose was to collect an uncontaminated sample inside the Ryugu surface.
Hayabusa 2 landed the rover on the surface of Ryugu two weeks after all the remnants of the bullets were removed and collected samples. This is the first time in history that material has been collected from the underground of an asteroid.
After completing soil extraction, Hayabusa 2 returned to Earth in November 2019 and arrived in orbit on December 5, 2020. And the next day, the capsule containing the sample was dropped from 200 km above the Earth into the Umera Desert, Australia. The capsule was retrieved the same day. Ryugu is a type C asteroid composed mainly of carbonaceous material. C-type asteroids contain more organic matter than S-type asteroids made of silicon (stone matter) or M-type asteroids made of metal. Therefore, it is more suitable for exploring the origin of life on Earth. About 75% of asteroids are type C.
After dropping the capsule on Earth, Hayabusa 2 left Earth orbit again and flew into space. The next target, at a distance of 10 billion km, is to explore the asteroid 1998KY26. The arrival of Hayabusa 2 in 1998KY26 is expected to be July 2031. If Hayabusa 2 succeeds in exploring the asteroid 1998KY26, it will gain the reputation of being the world’s first spacecraft to orbit around two asteroid bodies.
Ryugu’s soil samples were sent to research institutes around the world in June last year through JAXA. It was to analyze the constituents of the asteroid soil. The scientific community estimates that asteroids were formed when rock fragments formed immediately after the formation of the solar system 4.6 billion years ago. Therefore, asteroids contain only the environment of the early days of the solar system, so they are suitable clues to reveal the origin of the solar system. Ryugu is an asteroid presumed to contain material that existed in the primordial solar system.
The JAXA research team released the analysis results on the 9th following the 6th of June. According to him, organic matter was identified in the Ryugu soil sample at a ratio of 4% carbon, 1.2% hydrogen, and 0.17% nitrogen. In particular, more than 20 amino acids that make up proteins were discovered. Among the amino acids that make up the protein of the human body, valine and isoleucine, which cannot be synthesized in the body, were discovered, and glycine, a component of collagen, and glutamic acid, which is known as a component that gives flavor, were also confirmed. There are more than 80 kinds of natural amino acids found in nature, but only about 20 amino acids exist in the human body and are used for protein synthesis.
This is the first time that an amino acid, the basis of life, has been identified in soil samples taken from outside Earth. It means that the same materials that make up our bodies now exist in places other than Earth. In that respect, the results of this study give strength to the hypothesis that the origin of amino acids is the universe.
Water content in Ryugu soil sample
Scientists believe that amino acids were present on the Earth immediately after the birth of the solar system 4.6 billion years ago, but all amino acids were lost during the period when the Earth’s surface was covered with magma. Because of this, it has been assumed that meteorites that came from outer space after the Earth cooled and supplied these lost amino acids to the Earth. This is because there have been several cases of amino acids being detected in meteorites found on the ground.
However, the hypothesis that amino acids came from ‘alien’ was not fully accepted. This is because it is not certain whether the amino acids contained in the meteorite were originally created in space, or whether the meteorite came into contact with the earth’s atmosphere, sunlight, or soil during its return to Earth. Under such circumstances, this JAXA research team’s analysis came out.
The research team analyzed pure Ryugu soil that did not come into contact with the Earth’s atmosphere or soil, enough to support the hypothesis that meteorites from outer space supplied amino acids that were lost from Earth. It is highly likely that materials from space may have been involved in the birth of life on Earth.
Meanwhile, analysis teams from JAXA, Hokkaido University, and Tokyo Institute of Technology also announced that Ryugu soil contains water in the international scientific journal ‘Science’ on June 9th. Although not as abundant as the experts had originally expected, measurements of the sample’s chemical composition revealed that water accounted for 7% of its total mass. Of course, we did not discover liquid water. The water had already evaporated and remained in the sample as a hydroxyl group (OH) in which oxygen and hydrogen atoms were bonded. The research team analyzed that Ryugu’s soil sample was formed by contact with water from melted ice, only about 5 million years after the formation of the solar system. He also revealed that the Ryugu sample is the most primitive and uncontaminated pure material in the solar system that has been analyzed so far.
Following Hayabusa 1 and 2, JAXA is also conducting a project to explore Trojans. It plans to send a probe in 2025. In fact, asteroid exploration is very time-consuming and expensive. But why do we need to explore asteroids? This is because you can get three things: ‘understanding the early solar system’, ‘understanding the internal structure of the Earth and planets’, and ‘the process of how the planets in the solar system were formed’. It is hoped that Ryugu’s research on soil samples and exploration of the Trojan asteroid will shed light on whether the origin of life on Earth is the universe.
