Collision Experiment Shows How Water May Have Come to Earth

Researchers from Brown and John Hopkins University have shed light on how water may have first arrived on Earth, according to new research in the journal Science Advances. Water is one of the most common substances on our planet. Even so, nobody is sure how it initially got here. The question has perplexed scientists for years because, though there is a chance it came from ice-laden comets, it could have also come via a large collision.

“Water is critical to life as we know it, and it’s also essential to the evolution of planets,” explained lead author Terik Daly, a planetary geologist at Brown University, according to Popular Science. “Water changes the way rocks behave, so the timing of when water arrives on Earth really affects its geological evolution. We’ve known for awhile that asteroids and comets carry water, and that’s probably how water came to Earth. But the details of that process have kind of been a black box.”

To shed light on such mysteries, the team in the study used a super-sized gun at NASA’s Ames Research Center to recreate a meteor strike. That then allowed them a chance to see if such impacts had the ability to create water.

The team took the gun and used it to launch small rock pellets at a thin bed of pumice powder — a substance that is similar to the surface of an asteroid. That then simulated a water-rich asteroid slamming into the surface of another asteroid.

In the experiment, the rock hit the surface hard enough to melt both rock and pumice into a glass-like substance that held water. In addition, some of that water stuck around after the impact and did not dissolve. Some remained in the projectile blown apart by the impact, but a lot also mixed with the molten glass.

Those findings suggest that two colliding asteroids could potentially move water between them. While the research did not simulate how asteroid impacts affected large bodies like the Earth or the moon, scientists plan to follow up on the findings by closely analyzing asteroids in the solar system that have water signatures on their surface. That will help them better understand the results and potentially give them insight into how both our solar system and Earth first formed.