Meteorite study finds DNA, RNA bases

Japanese researchers reported in March that samples returned from asteroid Ryugu contained all five canonical nucleobases used in DNA and RNA, providing a peer-reviewed basis for social-media posts that circulated this week about “all DNA and RNA bases” in space rocks. The study was published March 16 in *Nature Astronomy* by Toshiki Koga and colleagues, who analyzed two Ryugu samples collected by Japan’s Hayabusa2 mission. They reported detections of adenine, guanine, cytosine, thymine and uracil in both samples. Nature said the findings came from uncontaminated extraterrestrial material returned from the carbonaceous asteroid. ### Which space rock did this study actually examine? Ryugu, not a newly fallen meteorite, was the core material in the paper behind the recent posts. The samples were collected by JAXA’s Hayabusa2 mission and returned to Earth in December 2020, according to coverage by the American Chemical Society’s *Chemical & Engineering News*. Koga’s team later received two grains sets — one from the surface and one from the subsurface — for a more complete nucleobase analysis. (natureasia.com) Nature’s press release said the researchers compared the Ryugu results with material from the Murchison and Orgueil meteorites and with returned samples from asteroid Bennu. That comparison is one reason some online retellings blurred “asteroid samples” and “meteorites,” but the headline result in the March paper was the Ryugu detection. ### Had scientists already found these molecules in meteorites before this? (cen.acs.org) NASA-backed researchers reported in 2022 that they had found the complete set of nucleobases used in life in carbon-rich meteorites, including the previously elusive cytosine and thymine. A NASA Goddard summary said earlier work had identified adenine, guanine and uracil in meteorites, while the newer techniques added the last two missing bases. The underlying 2022 paper in *Nature Communications* described detections of purine and pyrimidine nucleobases in three carbonaceous meteorites. (natureasia.com) Science News quoted NASA astrochemist Daniel Glavin at the time saying researchers had “completed the set” of bases found in DNA and RNA in meteorites. That means the 2026 Ryugu paper did not create the first-ever claim that all five had been seen in extraterrestrial material; it extended that picture to pristine asteroid samples returned under tightly controlled conditions. (science.gsfc.nasa.gov) ### Why are researchers treating Ryugu as a cleaner test case? Nature said detecting nucleobases in uncontaminated extraterrestrial material helps researchers study how such compounds can form without life and move through the Solar System. Ryugu samples are especially valuable because they were collected directly in space and sealed for return, reducing the contamination questions that follow meteorites after they land on Earth. (sciencenews.org) The *C&EN* report said Koga’s group also identified many structural isomers alongside the five canonical bases. Hannah McLain, an astrochemist at the University of Maryland, Baltimore County working at NASA Goddard, told the magazine the sample was “really tiny,” at about 20 milligrams total, underscoring how little material was available for the analysis. (natureasia.com) ### Does this mean life came from space? Toshiki Koga told AFP, in comments carried by Phys.org, that the finding “does not mean that life existed on Ryugu.” The study addresses prebiotic chemistry — the presence of molecules used by life — not living organisms, fossils or any evidence of biology on the asteroid. Nature’s press release said the authors concluded that nucleobases appear to be widespread in asteroid and meteorite materials and suggested carbonaceous asteroids may have contributed to early Earth’s chemical inventory. (cen.acs.org) That is a statement about possible delivery of ingredients, not proof of extraterrestrial life or proof that life itself began off Earth. ### What should readers watch for next? (phys.org) The March 16, 2026 *Nature Astronomy* paper is the primary document behind the current online discussion, and any follow-up debate is likely to center on abundance measurements, contamination controls and comparisons with Bennu, Murchison and Orgueil. JAXA’s Hayabusa2 samples and NASA’s Bennu return material remain the named reference points for the next round of astrobiology papers on prebiotic chemistry in carbon-rich asteroids. (natureasia.com)