Meteorite Reveals Violent Solar System History
A unique volcanic meteorite recovered in Western Australia several years ago by scientists indicates that our solar system has a violent past, according to a new study.
In 2007, planetary scientists from Curtin University captured on camera the meteorite falling on the Western Australia side of the Nullarbor Plain. Named the Bunburra Rockhole Meterorite, this celestial rock's unique characteristics suggest that it came from a large asteroid that has never before been identified.
Researchers believe the meteorite is evidence that a series of collisions of asteroids occurred more than 3.4 billion years ago.
"This meteorite is definitely one-of-a-kind," Dr. Fred Jourdan, from Curtin's Department of Applied Geology, said in a statement.
"Nearly all meteorites we locate come from Vesta, the second largest asteroid in the solar system. But after studying the meteorite's composition and orbit, it appears it derived from a large, unidentified asteroid that was split apart during the collisions," he explained.
The research team used the argon-argon technique, a well-known method for dating impact crater events, to determine the asteroid's bombardment history.
They obtained three series of ages indicating that the meteorite recorded three impact events between 3.6 billion and 3.4 billion years ago.
"These ages are pretty old by terrestrial standards, but quite young for a meteorite since most are dated at 4.57 billion years old, when the solar system began," Jourdan said.
"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," he added.
Jourdan says that the reason impacts stopped 3.4 billion years ago could be because after that time asteroids were too small to be targets for collisions, or because they were protected by regolith, a thick blanket of cushiony powder usually found at the surface of asteroids.
Regardless of why these collisions ended, Jourdan and colleagues are excited about their discovery, which reveals a little more about the impact history of our solar system.
The study's findings were published in the journal Geochimica et Cosmochimica Acta.