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Researchers detected the building blocks of DNA, shown here, in samples collected from the asteroid Ryugu. . |Image source: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, and Japan Industrial Technology Research Institute.
A “potentially hazardous” asteroid contains all the “letters” that make up DNA, suggesting these key ingredients for life may be common in the solar system.
Researchers made the discovery after analyzing samples collected from asteroid Ryugu, a 3,000-foot-wide (900-meter) space rock shaped like a spinning top.
Scientists have detected a complete set of typical nucleobases, which are DNA — the genetic basis of all life on Earth — and its lesser-known cousins RNAaccording to a new study published Monday (March 16) in the journal natural astronomy.
The lead author of the study said this “does not mean there is life on Dragon Palace” Toshiki KogaA biogeochemist at Japan’s Marine-Earth Science and Technology Agency told AFP, physical network. “Instead, their presence suggests that primitive asteroids could have produced and preserved molecules important for chemistry related to the origin of life.”
This isn’t the first time an asteroid has been found to carry all five nucleobases. NASA recovered the same set Nucleobases from asteroid Bennu 2023, by OSIRIS-REx spacecraft. The researchers also detected Nucleobases on meteorites. Taken together, these findings suggest that nucleobases may be widespread in the solar system.
The origin of life in the universe?
Scientists aren’t sure how life begins on earth. Some theories believe it originated here, such as deep-sea hydrothermal vents. However, it’s also possible that life – or the building blocks of life – didn’t form on Earth at all, but was brought here via comets or asteroids.
Cesar Menor SalvanAn astrobiologist at Spain’s University of Alcalá, who was not involved in the study, stressed in an interview with AFP that the new results “do not indicate that life originated in space.”
However, “through this and Bennu’s results, we have a very clear idea of what organic matter could have formed under the conditions leading to the origin of life anywhere in the universe,” Salvan added.
The Japan Aerospace Exploration Agency (JAXA) collected Ryugu samples during the Hayabusa2 mission launched in 2014. The unmanned Hayabusa2 spacecraft landed on the asteroid in 2019, then collected two dust samples from the asteroid’s surface and brought them back to Earth in 2020.
Each sample weighs just 5.4 grams (0.19 ounces), less than the weight of a quarter, but has excited scientists for years. Preliminary analysis of a small portion of material sampled in 2023 suggests the asteroid contains cornerstone of many livesinclude a nucleobase (uracil) and many other organic substances, including 15 amino acids, which are the building blocks of protein. These are prebiotic molecules, and although they are not life, they are present in all life.
One study also revealed Microorganisms crawl on a sample of asteroid Ryugu. But these microorganisms are so similar to bacteria on Earth that their presence is almost certainly the result of contamination of the samples after they were returned to Earth. (even NASA is in trouble Keeping Earth’s bacteria away from starships in apparently sterile chambers).
The Japan Aerospace Exploration Agency (JAXA) collected Ryugu samples by landing a spacecraft on the asteroid. |Image source: (left) JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, Japan Industrial Technology Research Institute. (right) Mascot/DLR/JAXA
The closest look so far
In the new study, the researchers used more sample material and optimized analytical techniques to conduct a more comprehensive analysis of the nucleobases than during the initial study.
This time, the researchers discovered all the nucleobases—adenine, guanine, cytosine, thymine, and uracil. These natural compounds are mixed with ribose and phosphate to form DNA and RNA. The researchers also looked at the nucleobase ratios and compared them with those found on Bennu and two meteorites that fell to Earth: Murchison and Allgaier.
The nucleobase is divided into two groups based on their chemical structure. Adenine and guanine are purines and are known for their double ring structure, while cytosine, thymine and uracil are pyrimidines with a single ring structure.
The researchers found that Ryugu contains equal amounts of purines and pyrimidines, while Bennu and Orgueil have higher pyrimidine content and Murchison has higher purine content. Notably, the researchers also found a strong correlation between purine-pyrimidine ratios and ammonia concentrations in Ryugu, Bennu and Orgueil, suggesting that ammonia is another life friendly elementsAccording to the study, it may be a key factor driving similar nucleobase formation pathways in different environments in rocks.
“Since no known formation mechanism predicts this relationship, this discovery may point to a previously unrecognized pathway for nucleobase formation in early solar system materials,” Koga said.
Related:
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— “Potentially Hazardous” Asteroid 2024 YR4 Is Earth’s First Real Planetary Defense Test
— Astronomers discover a skyscraper-sized asteroid hiding in the sun — and it’s moving at near record speed
Ryugu and Bennu are common asteroids known as carbonaceous asteroids, which make up 75% of all asteroids in the solar system. Observations from the James Webb Space Telescope (JWST) show Two asteroids may have originated from the same parent asteroid Divided billions of years ago. The Orgail meteorite also originates from carbonaceous asteroids.
These ancient rocks are leftover from when the solar system was still forming about 4.5 billion years ago, when the Earth was also forming. Thus, the detection of nucleobases suggests that carbonaceous asteroids may have helped Earth acquire life-forming chemicals.
“The detection of multiple nucleobases in asteroid and meteorite material suggests their widespread occurrence throughout the solar system and strengthens the hypothesis that carbonaceous asteroids contributed to the probiotic chemical inventory of early Earth,” the researchers wrote in the study.