All five DNA and RNA nucleobases found in samples from asteroid Ryugu, study reports
Japanese scientists report finding all five nucleobases in material returned by the Hayabusa2 mission, adding to evidence that ingredients for life were widespread in space.
A team of Japanese scientists has found all five nucleobases used in DNA and RNA in samples from the asteroid Ryugu, according to ScienceDaily. The outlet republished an article from The Conversation by Kliti Grice, a professor of organic and isotope geochemistry at Curtin University.
The study was published in Nature Astronomy. The samples were brought back to Earth in 2020 by the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA).
Nucleobases are nitrogen-containing organic molecules. ScienceDaily describes them as the "letters" of genetic information. The five are adenine and guanine, known as purines, and cytosine, thymine and uracil, known as pyrimidines. Combined with sugars and phosphates, they form nucleotides, the building blocks of genetic material.
In 2023, an international team reported finding one of the five, uracil, in the Ryugu samples. The new work confirms all five are present. The researchers analysed two samples and found the nucleobases in roughly similar amounts, the report says.
Hayabusa2 delivered 5.4 grams of asteroid material in total. Researchers worked in ultra-clean lab conditions to avoid contamination, extracting organic molecules with water and hydrochloric acid before purifying them.
Why it matters
According to the report, the finding means these ingredients for life may have been widespread across the early Solar System. Asteroids like Ryugu are remnants of that period and can preserve material largely unchanged for about 4.5 billion years.
Meteorites that land on Earth, such as the Murchison meteorite that fell in Australia in 1969 and the Orgueil meteorite that fell in France in 1864, have also yielded nucleobases. But those rocks can be contaminated during their journey and landing. Because the Ryugu samples were collected directly in space, ScienceDaily says they offer one of the clearest views of ancient Solar System chemistry. The report adds that samples from NASA's mission to asteroid Bennu also yielded all five nucleobases in 2025.
What is not known
The results suggest, but do not show, that key parts of genetic material formed in space and were later delivered to the early Earth. The report presents this as a possibility.
The mix of molecules also differs between space rocks. Murchison is richer in purines, while Bennu and Orgueil contain more pyrimidines. The report says it is thought that ammonia may influence this balance, but this is not presented as settled.
The report does not give the exact quantities measured in the Ryugu samples or name the members of the research team.
