- The estimated size of the object, prior to entering Earth's atmosphere, has been revised upward from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass has increased from 7,000 to 10,000 tons. Also, the estimate for energy released during the event has increased by 30 kilotons to nearly 500 kilotons of energy released. These new estimates were generated using new data that had been collected by five additional infrasound stations located around the world - the first recording of the event being in Alaska, over 6,500 kilometers away from Chelyabinsk. The infrasound data indicates that the event, from atmospheric entry to the meteor's airborne disintegration took 32.5 seconds. The calculations using the infrasound data were performed by Peter Brown at the University of Western Ontario, Canada.
"We would expect an event of this magnitude to occur once every 100 years on average," said Paul Chodas of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones."
The trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, which hours later made its flyby of Earth, making it a completely unrelated object. The Russia meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia.
From the European Space Agency:
- A space rock a few metres across exploded in Earth’s atmosphere above the city of Chelyabinsk, Russia today at about 03:15 GMT. The numerous injuries and significant damage remind us that what happens in space can affect us all.
While precise information on the size, mass and composition of the object are yet to be confirmed, videos show a fireball and explosion consistent with an asteroid up to a few metres in size exploding in the atmosphere, possibly several to ten kilometres above the surface.
In this type of event, if the explosion altitude is less than 10 km or so, the resulting shockwave can cause damage on the ground, such as shattering windows. Debris from the object may be found later.
“Current information, which is not yet complete nor confirmed, points to a small asteroid,” said Detlef Koschny, Head of Near-Earth Object activity at ESA’s Space Situational Awareness (SSA) programme office. “There is no way it could have been predicted with the technical means available today. What can be said with near certainty is that this object has no connection with asteroid 2012 DA14.”
- The scientists used updated information obtained by NASA-supported telescopes in 2011 and 2012, as well as new data from the time leading up to Apophis' distant Earth flyby yesterday (Jan. 9, 2013).
Discovered in 2004, the asteroid, which is the size of three-and-a-half football fields, gathered the immediate attention of space scientists and the media when initial calculations of its orbit indicated a 2.7 percent possibility of an Earth impact during a close flyby in 2029. Data discovered during a search of old astronomical images provided the additional information required to rule out the 2029 impact scenario, but a remote possibility of one in 2036 remained - until yesterday.
"With the new data provided by the Magdalena Ridge [New Mexico Institute of Mining and Technology] and the Pan-STARRS [Univ. of Hawaii] optical observatories, along with very recent data provided by the Goldstone Solar System Radar, we have effectively ruled out the possibility of an Earth impact by Apophis in 2036," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at JPL. "The impact odds as they stand now are less than one in a million, which makes us comfortable saying we can effectively rule out an Earth impact in 2036. Our interest in asteroid Apophis will essentially be for its scientific interest for the foreseeable future."
The April 13, 2029, flyby of asteroid Apophis will be one for the record books. On that date, Apophis will become the closest flyby of an asteroid of its size when it comes no closer than 19, 400 miles (31,300 kilometers) above Earth's surface.