Scientists have detected all five major nucleobases, essential components of DNA and RNA and genetic blocks of life, in samples collected from asteroid Ryugu. The discovery offers new evidence that some of the chemical ingredients needed for life existed in space billions of years ago.
The findings suggest that carbon-rich asteroids may have carried these compounds to early Earth, potentially contributing to the conditions that allowed life to emerge. Previous research has also examined when water and essential ingredients for life appeared on Earth.
The study, led by Toshiki Koga and published in Nature Astronomy, examined material returned by Japan’s Hayabusa2 spacecraft. The mission collected samples from Ryugu and delivered them to Earth in 2020.
Scientists identify all five nucleobases in asteroid samples
In 2023, researchers identified uracil, one of the five major nucleobases, in Ryugu samples. The new study has now confirmed the presence of adenine, guanine, cytosine, thymine and uracil. These nitrogen-containing compounds play an important role in genetic material. Adenine and guanine belong to a group called purines, while cytosine, thymine and uracil are pyrimidines. They combine with sugars and phosphates to form nucleotides, the building blocks of DNA and RNA.
Scientists have found all five genetic building blocks of DNA and RNA in samples from the 4.5-billion-year-old asteroid Ryugu.
The study also suggests that ammonia may have influenced how these molecules formed, offering new clues about the chemical origins of life on Earth. pic.twitter.com/28VJ5oahVX
— Tom Marvolo Riddle (@tom_riddle2025) November 3, 2026
Hayabusa2 returned approximately 5.4 grams of asteroid material. Researchers analyzed two samples under strict laboratory conditions to minimize contamination from Earth. The team detected all five nucleobases in both samples. The combined amounts of purines and pyrimidines were roughly equal.
Asteroid samples reveal different chemical conditions
The researchers compared Ryugu’s chemical composition with samples from asteroid Bennu and two meteorites, Murchison and Orgueil. Murchison fell in Australia in 1969, while Orgueil landed in France in 1864. Scientists previously detected several nucleobases in both meteorites.
In 2025, researchers also reported all five nucleobases in samples returned from Bennu by NASA’s OSIRIS-REx mission. Earlier analysis of NASA’s Bennu asteroid samples had revealed carbon-rich material and water-bearing minerals. The latest comparison revealed important differences. Murchison contained more purines, while Bennu and Orgueil had higher amounts of pyrimidines.
Researchers also identified a relationship between ammonia levels and the balance of these compounds. Samples with more ammonia generally contained a higher proportion of pyrimidines. The findings suggest that chemical conditions on each asteroid influenced how nucleobases formed.
What the discovery reveals about the origins of life
Asteroids preserve material from the solar system’s formation about 4.5 billion years ago. Unlike meteorites that fall to Earth, samples collected directly in space face a lower risk of contamination. The discovery strengthens evidence that nucleobases were widespread in the early solar system. It also supports the possibility that asteroids delivered organic compounds to Earth before life emerged.
Scientists continue to investigate the earliest evidence of life on Earth, although the direct role of asteroid-borne compounds in life’s origins remains uncertain.
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