If we need someone or something to blame the Chelyabinsk asteroid on, new research suggests the likely culprit was a larger asteroid that collided with its parent asteroid, knocking the Chelyabinsk chunk off and into an eventual collision course with Earth.
On February 15 2013, the asteroid exploded about 30 kilometers above Chelyabinsk, Russia, in what was the second largest asteroid burst in recorded history. Fragments of the meteorite were analyzed by Shin Ozawa and a team of researchers at Tohoku University in Sendai, Japan, and the results appeared recently in Scientific Reports.
Ozawa’s team focused on the fragments' shock-melt veins, which are created by the heat and pressure of an impact, causing parts of the asteroid to melt and later cool into a glass-like vein. The Chelyabinsk fragments contained the mineral jadeite which is only formed under extreme pressure and high temperature - in this case at least three to 12 gigapascals from a shock lasting over 70 milliseconds.
From this analysis of that bit of jadeite, the team determined that the 20-meter-wide Chelyabinsk asteroid was a piece of another asteroid that collided with a larger one measuring at least 150 meters in diameter that was traveling at around 4,800 kilometers per hour at the time of impact.
It appears the big bump occurred 290 million years ago. The chunk then took 280 million years to get pulled into the solar system’s asteroid belt, where it entered an orbit that put it on its collision course with Earth in 2013.
Previous calculations show that the asteroids in the belt have a life expectancy of less than 10 million years. This research confirms that they can survive much longer. Ozawa says the Chelyabinsk asteroid was unique.
It is a near-Earth object that actually hit the Earth, and its trajectory was well-recorded.
Now, if we can just find out who caused the collision so Chelyabinsk residents know where to send the repair bills.