Thursday, August 01, 2013

The Origin of the Russian Meteor Found


Scientists think they might have pinpointed where the infamous Russian meteorite of 2013 came from. Astronomers Carlos de la Fuente Marcos and Raul de la Fuente Marcos from the Complutense University of Madrid calculated that it likely originated as a piece of a near-Earth asteroid named 2011 EO40.

On the morning of February 15, the skies above Chelyabinsk, Russia lit up as an enormous fireball streaked out of the sky and exploded overhead. Scientists estimate that the meteorite was about the size of a six-story building. It's one of the biggest meteor impacts in recorded history, but it's a pretty small rock compared with some of the ones out there. It exploded 14 miles above the Earth's surface with the force of about 25 Hiroshima bombs, injuring about 1,500 people.



But where did it come from? To find out, the Spanish team ran a computer simulation calculating the different possible paths that could have slammed the errant asteroid into Earth. Astronomers were lucky that there were so many cameras that recorded the fireball, giving them a starting point to figure out its trajectory. The computer simulations gave them its most likely orbital path, which they could use to retrace its steps. They wanted to see if there was any chance it could have broken away from any known space debris nearby.

Using NASA's JPL Small-Body Database, a list of thousands of asteroids and comets orbiting the Sun, the team looked for any that might intersect the orbit they predicted for the Chelyabinsk meteor. The near-Earth asteroid 2011 EO40 lined up.

2011 EO40 was discovered in March of 2011 by asteroid hunter Richard Kowalski. It's roughly about 150 to 300 meters across, takes 2.13 years to orbit the Sun, crosses Earth's orbit and has been labeled a "potentially hazardous object." That that means that it has an orbit that crosses Earth's path and it's big enough to do some damage, but it doesn't mean that its likely to hit us any time soon.

Workers clean up broken glass after the Russian meteor
exploded in the sky above Chelyabinsk.
Image: Nikita Plekhanov
But it seems like a small piece of it may have broken away and grazed Russia in February.

Contrary to popular belief, asteroids are not all big solid rocks whizzing through space. The truth is many are nothing more than giant floating piles of space stones, bound together only by their weak gravity. It's not uncommon for chunks of rocks to calve off these rubble piles if they get jostled by gravity. That's what the researchers from Spain think happened to 2011 EO40.

If one piece broke away, its possible others did as well. The team identified about 20 very small chunks that may have broke away as well, but they're too small and dim to be easily track and calculate for sure. Even if they are from the asteroid, its extremely unlikely they'll come near to Earth, or big enough to pose any threat.

In order to confirm that asteroid 2011 EO40 was the parent of the Chelyabinsk meteor, astronomers would need take a spectrograph of it to compare whether the asteroid matches up with the bits of debris that landed throughout northern Russia.

The research paper was published on the ArXiv on July 30, and is slated to be published in a forthcoming issue of the Monthly Notices of the Royal Astronomical Society: Letters.

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