Samples retrieved from the C-type asteroid (162173) Ryugu by JAXA’s Hayabusa 2 mission reveal the presence of all five essential nucleobases: purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil). This finding suggests that fundamental aspects of life’s chemistry might have a cosmic origin.
Hayabusa2’s image of asteroid Ryugu taken from a distance of 6.9 miles, featuring a large crater at its center. Image credit: JAXA / University of Tokyo and partners.
Nucleobases are critical components of DNA and RNA, the molecules essential for life on Earth.
The detection of these compounds in pristine extraterrestrial materials enables scientists to explore how they form in non-biological contexts and how they traverse the solar system.
Prior analyses of Ryugu samples identified the nucleobase uracil. In comparison, investigations of materials from meteorites and the near-Earth asteroid Bennu have uncovered a broader spectrum of nucleobases.
“To properly evaluate the nucleobases within extraterrestrial materials, it’s crucial to examine samples minimally impacted by terrestrial factors,” explained Dr. Toshiki Koga from the Japan Agency for Marine-Earth Science and Technology and his team.
“In this scenario, raw asteroid samples that haven’t come into contact with Earth’s atmosphere hold significant scientific importance.”
Carbonate-rich particles found in the material samples from the near-Earth asteroid Ryugu. Image credit: Pilorget and colleagues, doi: 10.1038/s41550-021-01549-z.
The recent study involved analyzing two samples from Ryugu, collected by the Hayabusa 2 mission.
Both samples showed the presence of all five standard nucleobases: adenine, guanine, cytosine, thymine, and uracil.
The team compared their results with findings from the Murchison and Orgueil meteorites, as well as samples from the asteroid Bennu.
Significant differences in the relative quantities of nucleobases were observed.
Specifically, Ryugu exhibited roughly equal amounts of purine and pyrimidine nucleobases, whereas the Murchison meteorite showed a predominance of purines, while Bennu and Orgueil samples were richer in pyrimidines.
These variations reflect the distinct chemical, environmental, and evolutionary pathways of each parent body.
The identification of these nucleobases in asteroid and meteorite samples indicates their widespread presence across the solar system, despite chemical variations.
This discovery implies that carbonaceous asteroids may have played a role in shaping Earth’s early chemical landscape.
“Studying the original distribution and isotopic composition of nucleobases in other carbonaceous meteorites will yield key insights into the origins of these compounds and the astrochemical processes involving nitrogen-based molecules,” the researchers noted.
“The universal detection of all five standard nucleobases in Ryugu and Bennu samples underscores the potential for these extraterrestrial molecules to have contributed to the organic material that facilitated prebiotic molecular evolution, ultimately leading to the emergence of RNA and DNA on early Earth.”
Read the full study featured in this week’s issue of Nature Astronomy.
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Tetsuya Koga et al. A comprehensive set of standard nucleobases from the carbonaceous asteroid (162173) Ryugu. Nat Astron, published online March 16, 2026. doi: 10.1038/s41550-026-02791-z
Source: www.sci.news
