The Ryugu asteroid is rich in organic molecules that can serve as the building blocks of life. The discovery was made when scientists first saw samples collected from the asteroid by the Hayabusa2 spacecraft.
The Ryugu sample contained many so-called “prebiotic organic substances” including several types of amino acids that organisms use to build proteins that are important 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.
This finding adds further credence to the theory that the basic ingredients necessary to start the evolution of life on Earth could have been delivered to this planet in its infancy from outer space.
Related: Asteroid Ryugu: A warped space rock visited by Hayabusa 2
“The existence of prebiotic molecules on the surface of the asteroid despite the harsh environment caused by solar heating and ultraviolet radiation, as well as irradiation of cosmic rays under high vacuum conditions, shows that Ryugu grains on the upper surface have the potential to protect organic molecules,” he said. Lead author for the study and University of Kyushu researcher Hiroshi Naraoka, VA statement (Opens in a new tab). These particles could be transported throughout the solar system, and would likely disperse as interplanetary dust particles once they were ejected from the asteroid’s upper layers by impact or other causes.
The term “organic molecule” 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 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 the ingredients for life. The search for chemical processes that could give rise to life on Earth is known as “prebiotic chemistry”.
Also found in the Ryugu samples were organic biomolecules formed in the presence of liquid water, other vital components 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 largely consistent with what has been seen in some types of carbon-rich (carbon) meteorites that have been exposed to the most water in space,” said center scientist Jason Durkin.
So far missing from the Ryugu samples are sugars, components of DNA and RNA that have been found in other carbon-rich asteroids. The team suspects these compounds may be present in Ryugu but are below detection limits due to the small mass of samples examined for this study.
The Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 spacecraft collected samples from Ryugu, located approximately 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 ounces, 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 Ryugu samples that will be studied for years to come. This future investigation will include a comparison of the Ryugu sample with samples from the asteroid Bennu collected in 2020.
“We will be conducting direct comparisons of samples taken from Ryugu and samples from the asteroid Bennu when NASA’s OSIRIS-REx mission returns it to Earth in 2023,” Durkin said. “OSIRIS-REx is expected to bring back more samples than Bennu and will provide another important opportunity to search for the organic building blocks of life in carbon-rich asteroids.”
The team’s research is published in the Feb. 24 issue of the journal Knowledge. (Opens in a new tab)
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