Ryugu Samples Reveal Ancient Water Flow on Asteroid for a Billion Years

Researchers have discovered that liquid water ran through the asteroid that created Ryugu, a near-Earth, carbon-rich asteroid announced in 2015. Based on the microscopic samples returned by Japan's Hayabusa2 mission, the findings indicate that wet conditions within Ryugu's parent body continued for more than a billion years after its birth. These discoveries challenge the conventional wisdom that water-related activities on asteroids ended early in solar system history and provide additional insight into how Earth's oceans might have formed.

Ryugu's Ancient Water Traces Suggest Asteroids Helped Shape Earth's Oceans

As per a study led by researchers from the University of Tokyo, Ryugu preserved a “pristine record” of late water activity. The team studied the isotopes of lutetium and hafnium in their rock samples, finding signs that liquid water once flowed through the asteroid's minerals.

If water remained on these bodies for long periods of time, it suggests that asteroids such as Ryugu could have harboured and carried more water to early Earth than we ever thought,' explained associate professor Tsuyoshi Iizuka.

The team believes an impact on Ryugu's parent asteroid may have melted buried ice. It allows water to flow through cracks and chemically alter the rock. This process can break the parent body and form Ryugu. The finding points out that such asteroids may have played a remarkable role in shaping Earth's oceans and atmosphere.

Researchers developed advanced chemical techniques to trace out these subtle traces of water movement by using only milligrams of sample material. They now plan to study phosphate veins within the samples for more precise dating and to compare their results with NASA's Bennu asteroid mission.