Life’s Genetic Code Requires Five Key Ingredients. The Asteroid Ryugu Has All of Them, a New Study Suggests
The findings further hint that space rocks may have brought the building blocks of RNA and DNA to Earth long ago
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The asteroid Ryugu, millions of miles away from Earth, might not look that exciting. But on it, we now know, lie some of the most important molecular building blocks of life.
In a study published March 16 in Nature Astronomy, researchers report that all five molecular bases of DNA and RNA exist on Ryugu. Some scientists have long suspected that life’s basic ingredients may have arrived via asteroids colliding with our planet when it was young, and the findings support this idea.
Ryugu is not the first space rock to provide evidence of an early, violent galactic postal service. In 2025, scientists reported that the asteroid Bennu has the five molecular structures of genetic material, called nucleobases, as well as units that make up proteins. Two meteorites that crashed to Earth also contain the nucleobases.
In combination with past findings, however, the new study suggests that these building blocks are widespread, says study co-author Yasuhiro Oba, an astrophysical chemist at Hokkaido University in Japan, to Leah Crane at New Scientist. “Their detection in Ryugu strongly supports their ubiquity in the solar system.”
Asteroids are a strong source of astronomical history because they can preserve materials from the solar system’s early years around 4.5 billion years ago, writes Kliti Grice, a geochemist at Curtin University in Australia who was not involved in the study, for the Conversation.
To study one up close, the Japanese Aerospace Exploration Agency launched the Hayabusa 2 mission in 2014, in which a spacecraft traveled to Ryugu, blasted a crater into the asteroid and used rovers to collect exposed subsurface rocks. A return capsule brought about 5.4 grams of debris back to Earth in 2020.
Quick facts: About Ryugu
Ryugu is a roughly half-mile-wide asteroid that’s shaped like a diamond and full of carbon. When Hayabusa 2 reached it in 2018, the space rock was roughly 174 million miles from Earth.
Oba and his colleagues studied some of that material in an uber-pristine lab to avoid contaminating it with Earth material. They pulled out carbon-based organic molecules with water and hydrochloric acid and then purified them, revealing the nucleobases. When combined with sugars and phosphoric acid, these molecules can assemble into RNA and DNA, the genetic code for all life on Earth.
“Their results suggest key components of genetic material may have formed in space and [were] later delivered to the early Earth,” Grice writes. “In other words, the story of life on our planet may be deeply connected to the chemistry of such ancient asteroids.”
The five nucleobases fall into two main categories: purines and pyrimidines. Ryugu contains similar amounts of both types, the team found, which is different from the ratios in Bennu and the meteorites. These distinctions correlate with the amount of the chemical compound ammonia in the space rocks, which might provide a clue about how the genetic code molecules formed.
“This relationship suggests that ammonia may have played an important role in shaping the composition of nucleobases in these materials,” study co-author Toshiki Koga, a biogeochemist at the Japan Agency for Marine-Earth Science and Technology, tells Gizmodo’s Ellyn Lapointe. “Because no known formation mechanism predicts such a correlation, it may indicate that previously unrecognized chemical pathways contributed to the formation of nucleobases in the early solar system.”
Koga tells the outlet that he hopes future research will explore that possible link and other aspects of the chemical environments that may have fostered the formation of life’s building blocks.