Moscow: The Chelyabinsk meteor which exploded over Russia earlier this year, injuring more than 1000 people, was not a one-off - there are 20 more lurking on a similar path, Spanish astronomers have warned.
Scientists discovered that the Chelyabinsk bolide, an 18-meter wide 11,000-ton space rock that burst in a 460-kilotonne explosion above Russia, used to be a part of a larger space body.
Between 20,000 to 40,000 years ago, a massive body orbiting the Sun broke up, most likely as a result of the temperature extremes and planetary gravitation it experienced while looping out past Mars and Venus, researchers said.
The asteroid pieces formed an `asteroid family`, a group of asteroids that share same origin, composition and orbit, `RTnews` reported.
Astronomers have identified the parent of this potentially hazardous asteroid family as 2011 EO40. Those rocks are still flying somewhere in space, and just like the Chelyabinsk meteorite, their orbits could intersect with that of Earth.
Carlos de la Fuente Marcos and colleagues from the Complutense University in Madrid have found reliable statistical evidence for the existence of the Chelyabinsk cluster, or asteroid family.
Computer simulations of billions of possible asteroid orbits were used to find the ones most fitting into the Chelyabinsk impactor pre-collision orbit.
They then searched the NASA database of known asteroids to find out if any of them follow those orbits.
They spotted the Chelyabinsk bolide family of about 20 asteroids, which range in size from 5 to 200 meters across.
"It appears to include multiple small asteroids and two relatively large members: 2007 BD7 and 2011 EO40. The most probable parent body for the Chelyabinsk superbolide is [asteroid] 2011 EO40," researchers said.
The study points out that the shattered pieces of a rubble-pile asteroid can spread along the entire orbit of the parent body, making their collision with Earth possible on a time-scale of hundreds of years.
"More objects with the same orbital signature may encounter our planet in the future," Marcos said.