Asteroid Ryugu is a rubble pile of material from the formation of our Solar System. A new study of material returned by the Japanese Hayabusa-2 space probe shows that Ryugu, and likely objects like it, retained more water for much longer than previously thought. This water could have been delivered to Earth and other planets. Asteroid Ryugu photographed from a distance of about 12 miles (19 kilometers). Image credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu and AIST.

Hayabusa-2 Sample Return Mission Suggests Protracted Wetter Asteroids

by Andy Fell
September 17, 2025

New results from the Hayabusa-2 space probe show that asteroids formed at the very beginnings of our Solar System retained substantial amounts of water for hundreds of millions of years, potentially delivering water to Earth and other planets for much longer than previously thought. The work by a large international team, including Professor Qing-Zhu Yin at the UC Davis Department of Earth and Planetary Sciences, was published Sept. 10 in Nature.

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