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What We Know About the Russian Meteor Event [UPDATED]

We have the technology to provide warning about these potential disasters

Posted by Heidi Hammel

15-02-2013 14:26 CST

Topics: events and announcements, Earth impact hazard, meteorites, meteors

Correction: this post initially contained a typo that listed the mass of the meteor at 8 tons, we meant 8000 tons. Currently, the estimated mass 10,000 tons. -ed

Update Feb 21 - 11:19am PST 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.

The latest info can be found at: http://www.jpl.nasa.gov/news/news.php?release=2013-061

What we know (subject to change as more information comes in): At 9:20 a.m. local time in Russia, videos show an impactor coming in from the North. Asteroid 2012 DA14 is approaching Earth from the South. These two events are not related. The body is estimated to have been 15 meters across and weighed roughly 8 tons 8000 tons. The resulting airburst would have the equivalent yield of a 1-10 megaton 500 kiloton explosion. Note that these are very rough and extremely preliminary estimates.

Tim Swindle, director of the Lunar and Planetary Lab, released this from Peter Brown, one of the foremost expert on fireballs. The following is from Peter:

What follows are *initial* information gleaned for multiple instrumental sources recording various aspects of the Feb 15, 2013 airburst over Chelaybinsk, Russia (55.2N, 61.4E)

1. Time: The time of the main flare/airburst was 03:20:26 UT on Feb 15, 2013; the fireball began ablation about 30 secs before this time.

2. Based on the long duration of the event and videos, it is clear this was a very shallow entry (certainly less than 20 degrees, maybe more shallow).

3. It is *not* related to 2012 DA14

4. Energy: This is perhaps the hardest value to pin down so early in this investigation. From multiple sensors using multiple technologies a best initial estimate of the total energy of the event is about 300 kilotons of TNT equivalent = ~10^15 J). This could easily be in error by a factor of two. I am confident, however that it is in excess of 100 kTons, making it the largest recorded event since the 1908 Tunguska explosion.

5. Speed: The fireball entered the atmosphere at 18 km/s

6. Damage: The airblast clearly caused window breakage and light structural damage in downtown Chelaybinsk. The exact overpressure at which window failure occurs tends to be probabilistic and varies by construction design (ANSI S2.20, 1983). Normally some damage begins to occur around 500 Pa of overpressure, widespread window damage is expected to occur up to around ten-20 times this value. As the fireball had a shallow trajectory, the cylindrical blast wave would have propagated directly to the ground and would be expected to be intense. This could be further compounded by any fragmentation, quasi-spherical blasts. My impression is that the key here is that the terminal part of the fireball (probably between 15-20 km altitude) occurred almost directly over Chelaybinsk; this was perhaps the single greatest contributor to the blast damage (short range to the main part of the terminal detonation).

7. Comparators: The Sikhote-Alin fall (Feb 12, 1947) in the former Soviet Union was the equivalent of about 10 kilotons TNT, BUT as an iron impactor much of this energy was deposited at the ground rather than at altitude. The Oct 8, 2009 Indonesia event is the most recent similar event at about 50 kTons, but over the ocean.

8. Size: The pre-impacting asteroid was about 15 meters in diameter and had a mass of ~7000 tonnes.

I fully expect revision of some of the numbers above, particularly the estimate of the yield which could *easily* change by a factor of two upon more complete analysis and will likely change as the day progresses

According to NASA, the fact that it broke up in the atmosphere suggests that it was not an iron-nickel asteroid. We do expect fragments to be discovered on the ground. A much more quantitative estimate will come from analysis of the videos, the damage distribution, and the seismic reports. The timing of the shock wave, and the verbal and video reports, are consistent with verbal reports of the Tunguska event in 1908.

I describe the Tunguska event and show impact statistics. One of these megaton events occurs roughly every 100 years. Tunguska was 1908. I ask the audience to do the math.

In my "cosmic collisions" talk (which I've been giving for over a decade now), I describe the Tunguska event and show impact statistics. One of these larger events occurs roughly every 100 years. Tunguska was 1908. I ask the audience to do the math. This event was only a question of when, not if, and could have been anywhere on Earth. NASA has programs to detect potential impactors, but due to funding limitations, these searches have been focusing their efforts only on objects that would cause truly catastrophic events. LSST will likewise focus on larger bodies. Fortunately, this 2013 event was not a catastrophe, just a Really Bad Day in Russia.

We have the technology to avert such a disaster. After Comet Shoemaker-Levy 9 and these wake-up calls of 2012 DA14 and the newest Russian meteor blast, if we humans are done in by a rogue asteroid or comet, we have only ourselves to blame. That said, we probably can't stop these smaller ones from hitting Earth, since they are much harder to detect ahead of time. We can, however, give folks a few hours warning. A tornado siren does not stop tornadoes, but it gives people a chance to take cover. Had the folks in Russia been given even a few minutes warning, many injuries could have been avoided.

 
See other posts from February 2013

 

Or read more blog entries about: events and announcements, Earth impact hazard, meteorites, meteors

Comments:

Ethan Walker: 02/15/2013 05:26 CST

I understand that the estimates of size are preliminary, but a diameter of 15m is inconsistent with a mass of 8 tons. The volume of a 15m sphere is over 1700 m^3, which translates to .004 g/cm^3. Two or three meters would be believable.

Ethan Walker: 02/15/2013 05:28 CST

Ah. Or a much higher mass.

Nando Boston: 02/16/2013 01:28 CST

Thank you, however I am a bit confused when you talked about iron-nickel asteroid, and size of asteroid (# 8) , instead of a meteor. Thank you.

Casey Dreier: 02/16/2013 12:19 CST

@Nando: The term meteroid and asteroid have an ill-defined transition point (with a meteoroid being, essentially, a small asteroid. A meteoroid becomes a meteor when its in the sky. The chunks that make it to the ground are meteorites. The composition is still a guess based on the initial information. We'll have more as we hear it.

Kit Watson: 02/16/2013 05:58 CST

"Had the folks in Russia been given even a few minutes warning, many injuries could have been avoided." The folks in Russia *did* have 2 minutes and 20 seconds of warning. Many injuries *could* have been easily avoided. The problem here is that no one possesses sufficient knowledge of the physics of these events, nor the ability to effectively recognize the characteristics of such an event, to know that there is a great potential for an intense and damaging pressure wave minutes after the visual component. This 100-year event, *must* be a teaching moment for the entire planet. We adults must strive to understand and assimilate into our existence all that such an event portends. Teachers around the world *must* take this opportunity to explain to children what happened, why the damage occurred, and why it is so important to "duck and cover" immediately after witnessing such an event. If everyone in Chelaybinsk had the ability to quickly assess what this thing was in their skies, and immediately recognize that a blast wave was more than likel coming, there would have only been a handful of injuries, I am sure. Now is the time to gain and propagate this knowledge in society, so that it can be applied when the next one comes in!

EarthlingX: 02/16/2013 11:03 CST

If Tunguska event is once per 100 years, we are still waiting for it - this is not it, it's much smaller.

Steven: 02/17/2013 08:07 CST

I see the above comparisons but what about http://en.wikipedia.org/wiki/1972_Great_Daylight_Fireball ?

Marshall Eubanks: 02/17/2013 08:14 CST

Here is what I have been able to find about falls from the Russian meteor. The hole in the lack has been scoured, with nothing found at the bottom of the lake. http://www.upi.com/Top_News/World-News/2013/02/16/Divers-find-no-pieces-of-Russian-meteorite/UPI-97681361028430/ http://rt.com/news/chelyabinsk-fireball-damage-repair-387/ Russian authorities now think the hole formed “because of a different reason.” It may have been a (rather prompt) hoax, or a hole made by fishermen. Still, at least one small (mm sized) object was found on the ice of the lake near the hole http://74.mvd.ru/news/item/845855/ Pictures 4 and 5 from that web site are the only pictures I have found showing a potential fall. It may be that this meteor was a piece of a dead comet with no tensile strength, and there won't be any pieces bigger than a few mm. I think that more will have to wait on some local scientists coming up with a orbit, which should make it possible to predict where the strewn field is.

Marshall Eubanks: 02/17/2013 09:08 CST

Looking at the videos, I suspect that the Russia meteor may be a repeat of the 1972 Fireball (US19720810), in other words, a body that left the Earth's atmosphere, and also that it split into two major pieces (each of which may have left the atmosphere). This video (at 22-25 seconds) clearly shows that there are two bright objects that continue to move rapidly to the right, and then dim. They seem to be following a ballistic trajectory. http://www.youtube.com/watch?v=1W90i4nZZAQ The object clearly split - this video (and many others like it) clearly shows two trails http://www.youtube.com/watch?v=36w4Lh44dZg My guess is that the split was at the time of the extremely bright flash that saturated all of the nearby cameras. Note that (in the above video) there are multiple sonic booms, starting at 1:30 and continuing for some 20 seconds. That must reflect the passage of multiple objects. The passage of the Russian Meteor (which I guess we should start calling Chelyabinsk 2013) through the atmosphere is of course consistent with the failure to find a strewnfield.

Anonymous: 02/17/2013 09:47 CST

Marshall Eubanks Great comment! But I wonder what makes earth grazing meteors plausible. Our radius is about 13 000 km, the altitude of that meteor was about 1/1000 of that. Those should be extremely rare events, unless there's some gravitational or other explanation. I mean, if you throw a dart at an apple, how often will it grace its skin without penetrating it? The smoke traces maybe were only generated until some level of deceleration or disintegration, and therefor it looks as if it was passing by although its non-smoking fragments fell down later? Kit Watson I wanna give you a bit of a reality check there. Meteors that hurt people are very rare events. I think this is the first I've ever heard of. Slipping in the bathtub or crossing a road are much more dangerous events. So people make rational priorities. Meteors are entertainment for interested guys like you and me. It is not a threat. Those who don't care will thrive and live healthy ever after.

JimO: 02/17/2013 10:14 CST

I would also be very interested in eyewitness reports of electrophonic sound PRIOR to the acoustic shock -- that is, during the brightest flaring of the fireball. This is a at-long-last well-established effect of plasma-generated radio noise coupling into near-observer physical objects and creating a hissing or whooshing sound. It occurs simo with the visual flares, seems to come from 'all around' [not from above], has been reported for centuries by some bright fireball witnesses and pooh-poohed by scientists until work by Colin Keay and others established its validity.  See http://www.gefsproject.org/electrophones/index_history.html

Marshall Eubanks : 02/18/2013 12:21 CST

I swear, this is the same little pebble in the other picture. http://en.rian.ru/russia/20130217/179531203/Meteorite-Fragments-Found-in-Icy-Urals-Lake---Scientists.html but it does seem to be a meteorite : "This meteorite is an ordinary chondrite, it is a stony meteorite which contains some 10 percent of iron. It is most likely to be named Chebarkul meteorite,” Grohovsky said. I still have a feeling it skipped off the atmosphere.

Marshall Eubanks: 02/18/2013 12:30 CST

@anonymous I don't think a skip is as rare as that. Think of the Earth (from the meteorite's standpoint) as something like a circular dart board, such as you might see in a bar, with a big center (say, 6400 km in radius) and a small band around the rim (the region where the meteor would hit, form a trail, but be scattered off the planet. This region is fairly wide, say (to keep the math simple) 64 km. The area of the board is pi R**2, the area of the rim is 2 pi R dR, where dR is the vertical extent of the rim. The ratio of these is (to first order) the scattering probability, and it is 2 pi R dR / pi R**2 or 2 dR / R. Using the numbers, that's 2%. Now, 1 chance in 50 is not super high, but it is not that improbable. (The scattering band is large because it merges smoothly with the infinite region at higher altitudes, where the meteor never interacts with the atmosphere at all.)

Rock: 02/18/2013 06:01 CST

(I'm Anon 09:47 above) Thanks for your clarification, Eubanks. I wonder about the hole in the ice of that lake. It is quite circular. Is that to be expected from a meteor strike, maybe because it heated the water which then melted the ice symmeterically? Or is it an indication of it being a manmade hoax? Small fragments might be found all over the place. I suppose they have found them on the lake because that's where they've searched for it. And they are easier to spot there than in the forest. It doesn't need to indicate that any larger part hit the lake, I'd say. And can't they see if it left the atmosphere again, they have a missile defence, right, but they don't know it this one hit or missed the ground? Oh well, our beloved russians. Stuff from space always seems to drop down through their roofs over there. Google "cosmonaut street".

George: 02/18/2013 01:14 CST

@Rock -- I may be wrong, but I'm pretty certain its almost impossible for a meteorite that hits the ground to actually be hot enough to melt ice. These things are *cold* before they hit the atmosphere, and just don't have much time in the fire, so to speak, to really warm up much before hitting the ground. If it was going fast enough, maybe it could punch through ice, but AFAIK it can't melt its way through.

IcePilot: 02/18/2013 02:38 CST

Casey - If a meteoroid becomes a meteor when it enters Earth's atmosphere, would an asteroid become an aster in the very few seconds left before utter destruction? And what is the (ballpark) transition size?

Rock: 02/18/2013 03:22 CST

If not heat, then could the mechanic force of shockwaves create such a symmetrically circular hole in the ice? I'm intuitively sceptical, but "the establishment" seems to swallow it publicly, so I wonder how come. The cornflake sized meteor fragment found next to that hole is intriguing, but not very convincing.

jim oberg: 02/19/2013 10:08 CST

The source of the white trail is confusing to a lot of people, who are misled by terms such as 'contrail' and even smoke trail. It's a shock-induced chemical effect, and is best illustrated by these eyewitness accounts of the shuttle Endeavour fireballing across the SW US on its way to a Florida landing: http://www.jamesoberg.com/96mar-sts72_entry.pdf

marshall Eubanks: 02/19/2013 10:59 CST

This is a very cool map of all falls in history (!). There is obviously a strong population effect. http://www.guardian.co.uk/news/datablog/interactive/2013/feb/15/meteorite-fall-map

Marshall Eubanks: 02/19/2013 11:03 CST

This recent report makes it clear that there is a strewn field, but it mostly seems to be small pieces http://online.wsj.com/article/SB10001424127887323764804578312264130040432.html This article talks about the "gold rush" to find meteor fragments in the poor villages in the area. http://www.nytimes.com/2013/02/19/world/europe/russian-scientists-say-they-found-meteorite-fragments.html?_r=0

marshall Eubanks: 02/19/2013 06:18 CST

This is from twitter - a picture from an airplane (I know nothing more than that). @XB70AValkyrie Russian meteor photographed from an airliner over Chelyabinsk. #RussianMeteor http://twitpic.com/c4w5rb I do not know if that picture was taken from this flight, but it sounds likely : http://english.ruvr.ru/2013_02_18/Chelyabinsk-meteorite-made-close-shave-with-airliner/ If this picture is real, it may shoot down my of the main body of the meteor skipping off the atmosphere

Lawrence Squeri: 03/07/2013 08:41 CST

A Russian nationalist politician claimed the event was no meteor but the testing of a secret American weapon. Thank god this idiot does not have his finger on Russia's nuclear button. Imagine if the meteor were bigger and caused greater damage? If it had fallen on Mecca and wiped out the city, would Muslim extremists claim that the Zionists or Americans had attacked Islam and they would further claim that the "meteor" is a cover story. Instead of Mecca, choose any other city in the Muslim world and one gets the same horrible repercussions. Or perhaps our hypothetical meteor fell on Pyongyang, the North Korean capital. How would the paranoid North Korean government, which now has atomic capability, react? Earth's history is full of impacts from comets, asteroids, and meteors. It may turn out that the real disaster next time may not be the impact but the way humans react to it.

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