The asteroid Ryugu has all of the main ingredients for life

Samples from the asteroid Ryugu have revealed all five key ingredients for DNA and RNA. This finding bolsters the theory that asteroids could have delivered the essential components for life to Earth in the distant past.

Japan’s Hayabusa 2 spacecraft reached Ryugu in 2018, deploying two projectiles—one small, one large—into its surface to gather debris. The spacecraft returned to Earth with these samples in 2020, which researchers have been meticulously studying since then.

Yasuhiro Oba from Hokkaido University in Japan, along with his team, analyzed two different samples: one from the asteroid’s outer layer and another from materials beneath the surface, unearthed by the projectiles. Both samples contained all five primary nucleobases, the compounds that form the nucleic acids DNA and RNA when combined with sugars and phosphoric acid.

This discovery is not entirely unprecedented, as nucleobases have also been identified in meteorites and samples from the asteroid Bennu. However, the researchers observed variations in nucleobase abundance across different samples, suggesting these compounds could help trace asteroids and meteorites to their original parent bodies and provide insight into their evolutionary history.

The presence of nucleobases in samples from asteroids like Bennu and Ryugu underscores the potential role of asteroids in the origin of life on Earth. “Their detection in Ryugu strongly supports their ubiquity in the solar system,” says Oba. If asteroids throughout the solar system contain DNA building blocks, they may have contributed to the early development of life on Earth billions of years ago.

There is even the possibility that Ryugu and other asteroids could contain DNA and RNA themselves, beyond just their components. “It is very likely that more complex organic molecules like nucleic acids are formed on asteroids,” Oba adds. This possibility enhances the significance of asteroids in the context of life’s origins on Earth.