New research shows that liquid water flowed across the parent body of the near-Earth asteroid Ryugu much later than previously thought possible.

The discovery comes from analysis of rock samples collected by Japan’s Hayabusa2 mission between 2018 and 2019 and returned to Earth in December 2020.

By examining radioactive isotopes of lutetium and hafnium in the samples, scientists determined that fluids moved through the asteroid’s rocks over a billion years after its formation, likely triggered by an impact that fractured the parent body and melted buried ice.

This finding suggests that carbonaceous asteroids like Ryugu may have contained far more water than previously believed, implying that such asteroids could have delivered substantial amounts of water to early Earth, influencing its oceans and atmosphere.

Researchers emphasized the significance of conducting the study with samples smaller than a grain of rice, which required advanced techniques to isolate and analyze isotopes with extreme precision, Space.com has reported.

The team plans to study phosphate veins in the samples to better date the water flow and compare their findings with NASA’s Bennu samples to determine whether late water activity was unique to Ryugu or common among asteroids.