Violent Solar System History of Asteroid Collisions Revealed in Recovered Meteorite

Scientists are learning a bit more about the violent history of our solar system. By studying a unique volcanic meteorite recovered from Western Australia, scientists have found out that a series of collisions of asteroids occurred more than 3.4 billion years ago.

"This meteorite is definitely one-of-a-kind," said Fred Jourdan, one of the researchers, in a news release. "Nearly all meteorites we locate come from Vesta, the second largest asteroid in the solar system. But after studying the meteorites composition and orbit, it appears it derived from a large, unidentified asteroid that was split apart during the collisions."

The researchers dated the meteorite with an argon-argon technique. This method is usually used for dating impact crater events and sheds light on an asteroid's impact history. In this case, the scientists obtained three series of ages, indicating that the meteorite recorded three impact events between 3.6 and 3.4 billion years ago.

"Interestingly, the results also showed that not a single impact occurred on this meteorite after 3.4 billion years ago until it fell to Earth in 2007," said Jourdan. "The same impact history has also been observed from meteorites originating from Vesta with any impact activity stopping after 3.4 billion years ago. Obtaining similar information from two large, yet distinct asteroids is an exciting discovery as it confirms some of the bombardment history of our solar system."

So why did the bombardment stop about 3.4 billion years ago? It's possible that the asteroids were simply too small in size for collisions. Another explanation could be that they were protected by regolith, which is a thick blanket of cushioned powered that's usually found at the surface of asteroids.

The findings reveal a bit more about asteroid impacts in the beginnings of our solar system.

The findings are published in the journal Geochimica et Cosmochimica Acta.