In 2014, the Japan Aerospace Exploration Agency (JAXA) has its . sent Hayabusa2 spacecraft to meet 162173 Ryugu, a Near-Earth Asteroid (NEA) that periodically passes close to Earth. In 2018, this sample return mission reached Ryugu and spent the next year and a half studying the surface and obtaining samples of the surface and subsurface. By 2020, these samples returned to Earth, where scientists began analyzing them in hopes of learning more about the early history of the solar system and answering important questions about the origin of life.
Earlier this year, the first results of the analysis showed that Ryugu is (as expected) rich in carbon, organic molecules and volatiles (such as water) and hinted at the possibility that it once a comet† Based on a more recent analysis, eight teams of Japanese researchers (including one from JAXA) recently announced that Ryugu carries species of no less than 20 different amino acids — the building blocks of DNA and life itself! These findings could provide new insight into how life is distributed throughout the cosmos and could mean it’s more common than previously thought.
This research was started in 2021 by JAXA and numerous Japanese research institutions, including the University of Tokyo and Hiroshima University. Initially, the analysis found evidence of 10 types of amino acids, but that number has since grown to 20. Since C-type asteroids are composed of material left over from the formation of the solar system, the study of these ancient bodies could reveal things about their early history. Although samples of asteroids containing organic molecules have been found on Earth, it is uncertain whether they were the result of contamination from Earth’s biosphere.
One of the Hayabusa2 The main objectives of the mission were to determine whether there is a relationship between C-type asteroids and carbonaceous chondrites (CC) meteorites. This refers to meteorites that have been altered by water, as evidenced by the presence of clay minerals and salts in them. Scientists have suspected for some time that these meteorites come from C-type asteroids that originated in the far reaches of the outer solar system. These asteroids, made up largely of volatiles such as water ice, are believed to have brought water into our solar system billions of years ago.
In the case of the Ryugu samples, scientists have sought an answer to a long-standing question: are C-type asteroids responsible for water distribution? and the building blocks of life throughout the solar system via CC meteorites? by the Nebula hypothesis, the planets merged about 4.5 billion years ago from a disk of gas and dust that settled around the newborn sun. One theory suggests that na Earth growth of this disk, the planet’s surface was in a molten state that would have destroyed all amino acids. Gradually, meteorites brought them back to Earth after the surface cooled.
If this theory is correct, life on Earth originated thanks to organic matter that did not originate here, but was introduced by asteroids from the outer solar system (also known as lithopanspermia). Hiroshi Naraoka, a planetary scientist at Kyushu University and the leader of the team, explained at the Lunar and Planetary Science Conference in March:
“We detected several prebiotic organic compounds in the samples, including proteinogenic amino acids, polycyclic aromatic hydrocarbons similar to petroleum and several nitrogen compounds. These prebiotic organic molecules can spread throughout the solar system, possibly as interplanetary dust from the Ruygu surface through impact or other causes.”
Hayabusa2 was groundbreaking because it collected samples of underground materials that were not weathered by sunlight or cosmic rays. Kensei Kobayashi, professor emeritus of astrobiology at Yokohama National University, also explained how these findings have significant implications for astrobiology. “Proving that amino acids exist in the subsurface of asteroids increases the likelihood that the compounds arrived on Earth from space,” he said, adding that this is a possible indication of how “life could have arisen in more places in the universe.” than previously thought.”
Hayabusa2 is one of the few existing or proposed monster return missions dedicated to investigating the origin of life in the solar system. Between 2018 and 2021, NASA’s OSIRIS-REx also collected samples from the NEA Bennu, which will be returned to Earth by September 2023. China also plans to launch its own monster return mission known as Zhenghelaunching in 2024 and merging with the NEA Kamo’oalewa by 2032.
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