The asteroid Ryugu is rich in organic molecules that could serve as the building blocks of life. The discovery was made when scientists got their first look at a sample collected from the asteroid by the Hayabusa2 spacecraft.
Ryugu’s sample contains many so-called “prebiotic organic substances” including several types of amino acids that organisms use to build proteins that are essential for regulating chemical reactions and forming structures such as hair and muscles. These particles can also be created by various non-living processes, such as chemical reactions that can occur in asteroids.
The findings add further credence to the theory that the basic ingredients needed to begin the evolution of life on Earth could have been delivered to the planet in its infancy from space.
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“The presence of prebiotic molecules on the asteroid surface despite its harsh environment caused by solar heating and ultraviolet radiation, as well as cosmic ray irradiation under high vacuum conditions, indicates that the upper surface Ryugu grains have the potential to protect organic molecules,” said the lead author. For research and Kyushu University researcher Hiroshi Naraoka, V.A statement (Opens in a new tab). “These particles can be transported throughout the solar system, and are likely to disperse as interplanetary dust particles after being ejected from the asteroid’s upper layer by impacts or other causes.”
The term “organic molecules” describes a large group of compounds that contain the element carbon paired with hydrogen, oxygen, nitrogen, sulfur, and other atoms and are the building blocks of all life here on Earth.
These compounds can be created through chemical reactions that do not involve living organisms, which means that chemical processes inside asteroids can create ingredients for life. The search for these chemical processes that could have given rise to life on Earth is known as “prebiotic chemistry”.
Also found in the Ryugu sample were organic biomolecules that form in the presence of liquid water, another vital component of life, such as aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-containing heterocyclic compounds.
“So far, the amino acid results from Ryugu are mostly consistent with what has been seen in certain types of carbon-rich (carbonaceous) meteorites that have been exposed to the most water in space,” said center scientist Jason Durkin.
So far missing from the Ryugu sample are sugars, components of DNA and RNA that have been discovered in other carbon-rich asteroids. The team suspects these compounds may be present in Ryugu but they are below detection limits due to the small mass of the sample examined for this research.
The Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 spacecraft collected samples from Ryugu, located about 215 million miles (347 million km) from Earth, in February 2019. The samples were then returned to Earth in December 2020, and recovered in Japan. in 2021.
A small amount, 30 milligrams or about 0.001 ounce, of that sample, was analyzed by the International Soluble Organic Analysis Team at NASA Goddard in the fall of that year.
This new research marks the first organic analysis of a Ryugu sample that will be studied for many years to come. These future investigations will include comparing the Ryugu sample with samples from the asteroid Bennu collected in 2020.
“We will be doing a direct comparison of the samples taken from Ryugu and the sample from the asteroid Bennu when NASA’s OSIRIS-REx mission returned them to Earth in 2023,” Durkin said. “OSIRIS-REx is expected to bring back much more mass of samples than Bennu and will provide another important opportunity to search for the organic building blocks of life in a carbon-rich asteroid.”
The team’s research is published in the February 24 edition of the journal Sciences. (Opens in a new tab)
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