All Five DNA Building Blocks Found in Pristine Asteroid Ryugu Samples
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A Japanese research team has detected all five nucleobases—the fundamental genetic letters shared by DNA and RNA—inside pristine material returned from asteroid Ryugu, strengthening the idea that life's chemical ingredients were delivered to early Earth from space.
A team of Japanese scientists has confirmed all five nucleobases—adenine, guanine, cytosine, thymine, and uracil—in samples collected from the near-Earth asteroid Ryugu by JAXA's Hayabusa2 spacecraft. The 5.4 grams of material returned to Earth in 2020 were handled under strict contamination controls, placing them among the most pristine extraterrestrial matter ever studied. The team found the five genetic bases in roughly similar amounts across two separate Ryugu samples. This pattern differs from other carbonaceous bodies: the Murchison meteorite is enriched in purines, while Bennu and Orgueil contain more pyrimidines—differences thought to be shaped by ammonia. The finding mirrors results from NASA's mission to asteroid Bennu, which also yielded all five nucleobases in 2025. Asteroids such as Ryugu are remnants of the early Solar System capable of preserving materials largely unchanged for about 4.5 billion years—making them chemical time capsules of conditions that existed long before life on Earth. Researchers say their results suggest key components of genetic material may have formed in space and later been delivered to the early Earth, connecting the origin of life to a broader cosmic chemistry. The study was published in the journal Nature Astronomy.
