Scientists have made an astonishing discovery: liquid water once flowed through the parent asteroid of Ryugu, the carbon-rich near-Earth asteroid first identified in 2015. Microscopic samples brought back by Japan’s Hayabusa2 mission reveal that this asteroid’s interior remained wet for over a billion years after its formation. This remarkable finding upends long-held beliefs that water activity on asteroids ceased early in the solar system’s history and offers compelling new clues about the origins of Earth’s oceans.
Ryugu’s Watery Past: A New Perspective on Earth’s Oceans
A pioneering study by researchers at the University of Tokyo confirms that Ryugu holds an “unblemished record” of prolonged water activity. By meticulously analyzing lutetium and hafnium isotopes within the asteroid’s rock samples, the team uncovered irrefutable evidence of liquid water movement through its minerals.
Associate Professor Tsuyoshi Iizuka highlighted the significance: “If water persisted on these celestial bodies for such extended periods, it implies that asteroids like Ryugu might have harbored and delivered substantially more water to early Earth than previously imagined.”
The team theorizes that a significant impact on Ryugu’s original parent asteroid could have melted deeply buried ice. This event would have enabled water to seep through fractures, chemically altering the rock and eventually contributing to the parent body’s fragmentation and the formation of Ryugu itself. This theory underscores the potentially profound influence asteroids had on the development of Earth’s oceans and atmosphere.
To detect these faint indications of ancient water, the scientists employed sophisticated chemical techniques, working with mere milligrams of asteroid material. Their future plans include examining phosphate veins within the samples for more accurate dating and comparing their findings with data from NASA’s upcoming Bennu asteroid mission.
An embedded video further illustrates the scientific findings.