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Airburst Explained: NASA Addresses the Russian Meteor Explosion

A small asteroid entered Earth’s atmosphere early Friday, February 15, 2013 over Chelyabinsk, Russia at about 9:20 am local Russian time. Initial estimates, according to Bill Cooke, lead for the Meteoroid Environments Office at NASA’s Marshall Space Flight Center, is that the asteroid was about 15 meters (50 feet) in diameter, with a weight of 7,000 metric tons. It hit the atmosphere at a shallow angle of about 20 degrees, at a speed of about 65,000 km/h (40,000 mph).

It traveled through the atmosphere for about 30 seconds before breaking apart and producing violent airburst ‘explosion’ about 20-25 km (12-15 miles) above Earth’s surface, producing an energy shockwave equivalent to a 300 kilotons explosion. That energy propagated down through the atmosphere, stuck the city below – the Chelyabinsk region has a population of about 1 million — and windows were broken, walls collapsed and there were other reports of minor damage throughout the city.

The official impact time was 7:20:26 p.m. PST, or 10:20:26 p.m. EST on Feb. 14 (3:20:26 UTC on Feb. 15).

Cooke said that at this time, the known damage is not due to fragments of the bolide striking the ground but only from the airburst. “There are undoubtedly fragments on the ground, but at the current time no pieces have been recovered that we can verify with any certainty,” Cooke said during a media teleconference today.

A meteorite flashes across the sky over Chelyabinsk, Russia, taken from a dashboard camera.

A meteorite flashes across the sky over Chelyabinsk, Russia, taken from a dashboard camera.

He added that the space rock appears to be “an asteroid in nature,” – likely a rocky asteroid since it broke apart in the atmosphere. It wasn’t detected by telescopes searching for asteroids because of its small size, but also because “it came out of the daylight side of our planet – was in the daylight sky and as a result was not detected by any earth based telescopes. #RussianMeteor was not detected from Earth because it came from the daylight side (i.e the Sun-facing side of Earth).

The meteor left a trail in the sky about 480 km (300 miles) long.

Cooke, along with Paul Chodas, a research scientist in the Near Earth Object Program Office at NASA’s Jet Propulsion Laboratory said that asteroids this size hit the Earth on average about once every 100 years. “These are rare events, and it was an incredible coincidence that it happened on the same day as the close flyby of Asteroid 2012 DA14,” Chodas said. “The two are not related in any way.”

The Russian meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia. Oddly enough, the Tunguska event was caused by an object about the size of 2012 DA14, the asteroid that flew by Earth today harmlessly. The meteor, which was about one-third the diameter of asteroid 2012 DA14, became brighter than the Sun, as seen in some of the videos here. Its trail was visible for about 30 seconds, so it was a grazing impact through the atmosphere.

There were certainly pieces that hit the ground, according to Jon M. Friedrich from Fordham University. “For something that created a bolide and sonic detonation of the size seen in Russia, it seems likely that fragments reached the earth,”Friedrich said in an email to Universe Today. “In fact, there are reports of a crater in a frozen lake and other locations that were in the path of the meteor. The resulting fragments are not likely large – I’d expect some of the absolute largest to be football to basketball sized, with many fragments being smaller, like marbles.”

Chodas said that defending the Earth against tiny asteroids like this is challenging issue, “something that is not currently our goal,” he said. “NASA’s goal it to find the larger asteroids. Even 2012 DA14 is on the smaller size. The tiny asteroid that hit over Russia is very difficult to detect, an in order to defend the Earth, the problem and issue there is to find these things early enough to do something about it if we wanted to divert it. While smaller asteroids are easier to divert, they are much more difficult to detect.”

“What an amazing day for near Earth objects,” Chodas said, “with two events happening on the same day.”

The lead animation courtesy of Analytical Graphics, Inc.

About 

Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

Comments on this entry are closed.

  • Craig Temple February 15, 2013, 11:41 PM

    Credit to NdGT: Asteroids are nature’s way of asking: “How’s that space program coming along?”

    • Woodrow Wotan February 16, 2013, 12:40 AM

      Earth is the cradle of our species.

      No species is meant to live forever in the cradle.

      • Organ_Morgan February 16, 2013, 6:54 PM

        All species leave their cradles, so this is merely a truism.
        Do you have a point?

        • Woodrow Wotan February 16, 2013, 8:11 PM

          Yeah, but I’m combing my hair over it nowadays.

  • GregtheThird February 16, 2013, 2:18 AM

    What are the odds of these two asteroids getting this close to earth on the same day? It would seem like the heavens are trying to get our attention. Mystics and occultists will probably be talking about the portent of this day for centuries.

    • Olaf2 February 16, 2013, 2:57 AM

      Odds? A lot of asteroids are coming close that size. It is only because it entered the atmosphere that it was noticed.

      And so far the Mystics and oculists FAILED to predict this one. And those that they predict FAIL also.

      • Alejandro Garcia Crespo February 16, 2013, 10:32 AM

        That’s a WIN straight answer xD

      • GregtheThird February 19, 2013, 7:05 AM

        Evidently, but that doesn’t stop them from trying and amusing me in the process.

    • Skipdallas February 16, 2013, 4:59 PM

      I seriously doubt that anyone will be talking about this next month let alone centuries from now.

      • Lorin Ionita February 18, 2013, 10:03 AM

        Actually somebody will talk about it in the future. The Russian grandsons will hear something like this “One time, when I was young, I lived through a freaking asteroid”

      • GregtheThird February 19, 2013, 7:00 AM

        You don’t know much about the mystic fringes then. I bet there will be 30 minute segments on the future equivalent of cable channels still running 100 years from now about what the meaning of this day portends for future events.

        • Skipdallas February 19, 2013, 12:14 PM

          You are correct: I do not know about mystic fringe crazies and their strange and rather silly conjectures.

    • Qev February 16, 2013, 3:14 PM

      100%, apparently. ;)

    • GregtheThird February 19, 2013, 7:33 AM

      Rather than try to ridicule my post I did some research to help me answer my own question. To enlighten everyone, I got 1 in 100 million for the odds of 2 asteroids to come this close on the same day. For those who don’t get the fact that I was using humor in reference to the mystics, then I would just say they must have slept through the mandatory humanities courses in undergrad school.

  • danangel February 16, 2013, 3:17 AM

    A warning shot across our bow. Are we going to do anything with it? Seems someone is trying to wake us up.

    • zkank February 16, 2013, 4:10 AM

      I hope you’re not suggesting that somehow this was controlled by “someone”!

      “Warning shot”?! Too silly!

      As silly as one CNN news anchor last week suggesting that DA14 2012 might somehow be a result of “global warming”.

      • Qev February 16, 2013, 3:16 PM

        I think danangel is thinking in terms of a natural event serving as a “wake up call” as opposed to the agency of some malicious intelligence. :)

  • Tony Power February 16, 2013, 5:18 AM

    Could it be that there are a swarm of these meteors out there associated to the DA14 2012 body that are too small to be detected by our radars?

    • donarb February 16, 2013, 6:36 AM

      Asteroids are not detected using radar. They essentially take multiple pictures of the sky and compare them looking for moving objects. But there is a limit to the size of objects that can be detected.

      • Tony Power February 16, 2013, 6:52 AM

        The US Space surveillance network can detect objects out to 30,000 KM, shouldn’t this be able to detect these objects?

        • Tony Trenton February 16, 2013, 8:06 AM

          At +- 65,000 km /hr ? That leaves less than half an hour to do something!

          What do you suggest ?

          • Tony Power February 17, 2013, 11:31 PM

            Sorry, I wasn’t trying to seggest anything along the lines of stop it or evacuate, just asking, could there be a group of these meteors out there on the same trajectory as DA14 2012, perhaps as a result of a colision or something.

            Could they be part of the same parent asteroid, and if so the pieces that fall to earth could reveal more about DA14 2012 that we would otherwise have been able to learn.

          • Tony Power February 17, 2013, 11:33 PM

            Also I haven’t seen anything about what DA14 2012’s orbit has done? Has it’s near miss with us pulled it into an orbit that would bring it our way again?

      • space_sailor February 16, 2013, 12:35 PM

        we know orbits of even smaller asteroids. One of them (size 8m) passed Earth at 190.000 km last week. So I`m suprised that we completly missed that one. BTW – there should be a lot of debrises so I`m looking for news what kind of body it was.

  • Tom Watson February 16, 2013, 10:49 AM

    7,000 metric tons is that right? all other sources say it was about 10 tons…anyone??

    • kurteren February 16, 2013, 12:03 PM

      That was the initial estimate made without any real data, and the news agencies just repeat that figure as if it’s somehow valid. The higher estimate is based on data now available, and is therefore more reliable. It’s quite certain that a ten ton object would not be able to create an explosion of this magnitude, even if it was instantly completely vaporized.

      • Qev February 16, 2013, 3:17 PM

        I think the estimated energy output has been raised again, to close to 500 kt-equivalent, as well. Interesting times…

  • Chetan Chauhan February 16, 2013, 11:14 AM

    Wow , unimaginable.
    That thing was moving relative to us @ almost 20km/SECOND . The kinetic energy with something travelling at that speed is phenomenal.
    The funny thing is everyone was afraid and worked up about 2012 DA14 hitting the Earth. Instead this meteor came right out of the blue and actually hit the Earth. It would be very interesting to find out what size , and whether it was a metallic meteorite.

    Also a trail of 480km means the meteorite was in the Sky for hardly 20-30 seconds travelling @ 20km/second.

    • lcrowell February 17, 2013, 5:18 PM

      The kinetic energy is easy to compute. With a mass of 7000 tons, a velocity of 20km/s and KE = 1/2mv^2 this energy is

      KE = .5*7×10^6kg*(2.0×10^4m/s)^2 = 1.4×10^{15}j.

      A ton equivalent of TNT is 4.18×10^9j and so this is the equivalent of 334 kilotons of explosives. The hard work was trying to estimate the kinetic energy of the bolide from the energy of the shock wave at various distances from the estimated burst point or origin of the shock front.

      LC

  • Dav_Daddy February 16, 2013, 12:01 PM

    It is one heck of a coincidence this asteroid hitting roughly 12 hrs before another one is supposed to make a close pass.

    However seeing as how this one was about 300,000 miles in front of and coming from a different direction than 2012 DA14 it is just that a coincidence.

    I found a good graphic showing the different trajectories here: http://scienceblogs.com/startswithabang/files/2013/02/MarkOliverTelegraphUK.jpeg

    • lcrowell February 17, 2013, 5:10 PM

      The known orbital ephemeris of 21012DA14 and the estimated orbit of this bolide exclude the possibility these two have any direct physical or causal relationship.

      LC

  • Aqua4U February 16, 2013, 6:33 PM

    Subject: Population control, the hard way.

    Our poor little planet is suffering from an overabundance of large brained but stupid hominids. There are FAR too many people on this planet for a reasonable and sustainable future for our species? We have poisoned the land, sea and atmosphere with our greed driven activities. We live in a time where a ‘tipping point’ toward extinction has become a very real probability. It doesn’t look good for our children – yet might become a moot subject if ‘the problem’ suddenly evaporated with an instantaneous cosmic intervention.

    Perhaps an advanced ETI might choose to intervene (again?) on the behalf of lesser species, giving them a chance to evolve, with a large asteroid or comet? Benevolence in a far removed consciousness may appear destructive at best? But as fire releases seeds from some kinds of trees.. nature finds a way.

  • danangel February 17, 2013, 1:06 AM

    Right you are. Maybe I could have said it better, but something has to wake up enough people to force the government to take notice and actually prepare for when that near miss is a little too ‘near’.

  • katesisco February 17, 2013, 1:23 PM

    Let’s consider this was a delivery from the sun, a gas ball. As such it would be hard to id with satellite, no?

    • Lorin Ionita February 18, 2013, 10:17 AM

      How would it stay coagulated in space?

  • bugzzz February 17, 2013, 10:39 PM

    The timing of the two events is uncanny. I don’t particularly believe in coincidence, so I might suggest that the timing of the Russian event is actually a helpful cosmic assist highlighting the dangers of far larger potential asteroids in the future. If that helps focus more public attention on the issue then the second event has greater significance than might first appear.

    • hjs GER February 18, 2013, 8:29 AM

      Objects of a size under 5 to 10 meters moving through lunar orbit are very frequent and will hardly ever be detected when still more than 1 hour away from Earth. Statistically a few dozens or so have done so since 2012 DA14 went by. But they have not come close to the stratosphere, so we don’t know of them. If one pointed straight to Berlin or to Washington tomorrow, we would not know today, and we could not. And I do not think we will in 20 years, in order to send out a spaceship in time, to tell the guy to get the hell out of here. And if you don’t believe in coincidence, then you may believe in destiny, God, Thor’s hammer or in determination. But be sure you can define none of these lexemes logically.

  • bugzzz February 19, 2013, 5:35 PM

    Yes, I believe in destiny and ‘god’ or some form of intelligent universe. Maybe a virtual reality with us all running on god the machine. The existence of the universe is inherently paradoxical since it cannot exist without something setting it in motion, and whatever set it in motion can also not exist without a cause, unless the answer is existence is a contradiction. An unresolvably so, which I am fine with.

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