An asteroid that exploded last year over Chelyabinsk, Russia, leaving more than 1,000 people injured by flying glass and debris, collided with another asteroid before hitting Earth, new research by scientists shows.
Analysis of a mineral called jadeite that was embedded in fragments recovered after the explosion show that the asteroid's parent body struck a larger asteroid at a relative speed of some 3,000 mph (4,800 kph).
"This impact might have separated the Chelyabinsk asteroid from its parent body and delivered it to the Earth," lead researcher Shin Ozawa, with the University of Tohoku, wrote in a paper published in the journal Scientific Reports.
The discovery is expected to give scientists more insight into how an asteroid may end up on a collision course with Earth. Scientists suspect the collision happened 290 million years ago.
Analysis of recovered Chelyabinsk meteorites revealed an unusual form of jadeite entombed inside glassy materials known as shock veins, which form after rock crashes, melts and resolidifies.
Jadeite, which is one of the minerals in the gemstone jade, forms only under extreme pressure and high temperature. The form of jadeite found in the Chelyabinsk meteorites indicates that the asteroid's parent body hit another asteroid that was at least 492 feet (150 meters) in diameter.
In an email, Ozawa described the Chelyabinsk meteorite as "a unique sample."
"It is a near-Earth object that actually hit the Earth, and its trajectory was well-recorded," Ozawa wrote.