Water-Bearing Asteroid Discovery Fuels New Theories of Earth Ocean Formation

Scientists are hailing an ancient water finding on a nearby asteroid. It’s a major breakthrough in our knowledge of how Earth's oceans formed, they say. 

Based on the finding, the asteroid Ryugu held water for over a billion years longer after it first formed. This is much longer than was thought. The finding could upend former theories about how Earth’s oceans formed.     

Asteroids like Ryugu carried vital compounds to Earth. Water was one. Phosphorus and nitrogen were others. The finding that they carried the liquid for far longer is important. It means that conditions ripe for life on Earth could have come about more slowly. That, and much more of Earth’s water could have come straight from asteroids with water that struck the planet than from inside it, scientists say. Microscopic life is believed to have first appeared on Earth 3.5 billion years ago. 

Scientists long believed that Earth’s water emerged through a mixture of comet and asteroid impacts and chemical processes within the planet. But the main view was that much of the Earth’s water derived from water forming from hydrogen and oxygen under its surface.  

“The idea that (objects like Ryugu) held on to ice for so long is (stunning),” Tsuyoshi Iizuka said in a statement. Iizuka's a research team member. Iizuka's also a University of Tokyo scientist. “It suggests that the building blocks of Earth were far wetter than we (thought). This forces us to rethink (how our planet’s water system began),” he said.

Ryugu samples were studied by the research team. The samples were gathered during the Japanese Hayabusa2 mission. The craft landed on the asteroid in 2018. It returned to Earth two years later. Ryugu is believed to contain some of the solar system’s most ancient substances. These date back to its birth 4.6 billion years ago.  

Reflect: What kinds of discoveries about space make you most curious?

Photo of an asteroid from Unsplash courtesy of NASA Hubble Space Telescope.