Japanese Team Lands First-Time Discovery of Building Blocks of Life from an Asteroid

More than 20 amino acids have been discovered by Japanese researchers on the space rock Ryugu, which is more than 320 million kilometers from Earth.

Scientists studied samples from the said near-Earth asteroid. The samples were retrieved by the Japan Aerospace Exploration Agency's (JAXA) Hayabusa2 spacecraft, which landed on Ryugu in 2018. This was the first time that signs of life were discovered on an asteroid.

In 2019, the spacecraft collected 5.4 grams from the surface and subsurface of the asteroid, stowed it in an airtight container, and returned it to Earth on a precise trajectory.

Near-Earth Asteroid Ryugu

Ryugu is made up of many small rocks rather than a single large boulder, and scientists believe the asteroid's unusual spinning top shape is due to rapid rotation.

Ryugu is a carbonaceous, or C-type, asteroid with a lot of carbon-rich organic matter on it, most of which were made from the same nebula that gave birth to the Sun and the planets of the Solar System approximately 4.6 billion years ago. The asteroid may also contain water, as per previous sample analysis.

While outlining the initial findings at the Lunar and Planetary Science Conference in March, Hisayoshi Yurimoto, a geoscience professor at Hokkaido University, pointed out that the Ryugu material is the most primitive in the Solar System ever studied. Yurimoto is the leader of the Hayabusa2 mission's initial chemical analysis team.

The pitch-black asteroid samples, which reflect only 2% to 3% of the light that hits them, have not been altered by interactions with Earth's environment, giving them a chemical composition with better resemblance with that of the early solar system. Such characteristic is unlike the organic molecules found on earth.

Hiroshi Naraoka, a planetary scientist at Kyushu University, explained that their team detected various prebiotic organic compounds in the samples, including proteinogenic amino acids, and polycyclic aromatic hydrocarbons similar to terrestrial petroleum, and various nitrogen compounds. Naraoka is the leader of the team which looked for organic matter in the samples.

He went on to say that these prebiotic organic molecules have the potential to spread throughout the Solar System, possibly as interplanetary dust from the Ruygu surface due to impact or other factors.

According to Japan's education ministry, sample analysis initially detected 10 amino acid types, but the number has now surged to more than 20. Amino acids are the basic building blocks of all proteins and are highly necessary for life to exist on Earth.

Read also: Oxygen in Earth's Atmosphere Could Help Identify Signs of Life Beyond Our Solar System 

Signs of Life

Organic molecules from space were discovered in a group of 3.3 billion-year-old rocks discovered in South Africa, according to a 2019 study published in the journal Geochimica et Cosmochimica Acta, raising the possibility that some, if not all, of these life-building molecules first reached the Earth through comets and asteroids. The Ryugu findings support the case that asteroids carry these molecules.

Kensei Kobayashi, a professor emeritus of astrobiology at Yokohama National University, gave a statement to Kyodo News, saying that proving amino acids exist in the subsurface of asteroids increases the probability that the compounds originated from space.

According to Kobayashi, amino acids could be found on other planets and natural satellites as well, indicating that life may have originated in more places in the Universe than previously thought.

Ryugu samples are still being analyzed, and more data about the asteroid's development and composition will be available soon.

Aside from Ryugu other space rocks are being studied. Another diamond-shaped asteroid named Bennu was sampled by NASA's OSIRIS-REx spacecraft in 2021.

Samples from Bennu are expected to reach Earth in 2023. Scientists are leaning on the possibility that signs of organic matter contained within the collected samples could provide important clues into the evolution of the solar system and its materials, and how life emerged from them.

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