Bolide Shockwave Injures 1000+ in Russia: Black Swan — or I Told You So?





The Bos!

Slow feed but great vids

Plugged!: Younger Dryas Impact Event

Feb Fireball Season

San Fran

Cuba and video



Brazil 2012

Iowa 1875 and here


Fireball Hush-Up?

NASA Urges Vigilance for Weird Fireballs

NASA 2012 Press Release “The Fireballs of February”

Year of the Snake?

Black Swan

As readers know, the Tusk is generally uninterested in current events related to our subject. We stick to the past unless we simply cannot ignore the present. But, in the end, we study the past so that we may be more prepared for what happened this morning in Russia.

This humble blog has some of the most informed and open-minded readers in fields related to this event of any source on the internet. I hope our regular commentors and others will develop an informative thread of observations.


  • E.P. Grondine

    George, Steve –

    “proxy” is used for the HSIE impactites, that data being a “proxy” for proved surface impacts.

    LDG is not a “proxy”. It is impact glass, data, and contains elements from the impactor which created it.

    Just to clear up some further confusion, at Chelybinsk you had the plumes from surface ablation, and then you had the bright IR release and blast wave from the bolide. Two separate energy conversions.

    Some large fragments of the meteoroid survived the bolide and traveled on at lower speed, but none of the plasma of the bolide did. Most likely this was because of earlier fractures of the meteoroid.

  • E.P. Grondine

    Finally and separately, Boslough’s model. Boslough maintains based solely on ONE data point that the plasma from the bolide conserves momentum.

    The two problems: there are not second data points. And his first and only data point has limited study as to the meteoroid plasma/heat energy distributions within the entire field of it.

    This data is what Boslough would need to verify his computer model.

    Like I said, IMO, he’s not that good.

  • Barry Weathersby
  • Barry Weathersby

    Oops… Delete my name from the end of that URL.

  • Trent Telenko

    >>If you want a first order approximation, the impact data seems to indicate that 30 meter
    >>cometissimals explode with 5 kilotons of energy at 5 kilometers altitude, while 60 meter
    >>cometissimals explode with 15 megatons of energy at 5 kilometers altitude.


    That is an extremely useful set of numbers for FEMA types.

    If you could get some sort of ground foot print based on angle of entry to go with it, you have a 1st responder planning tool.

  • Steve Garcia

    Hermann –

    I found this photo from the airliner (it might possibly have been a second one – not sure):

    It shows the steep down slope pretty well.

  • Steve Garcia

    Location: Cement plant at Pervomaisky, about 8 km SW of Korkino. From the video – Definitely right under it AND right under the big burst. From other sources Pervomaisky was directly under the path. One burst was

    From my other sources, one burst was 20 km east, and one was 15 km west – and one burst was freaking right over it, exactly.

    A new video to me. People looking at the trail from directly below, when loud bangs are heard. I counted at least seven nearby and three more at some distance, maybe four.

    This implies that they were NOT noises from only the “explosions” above, but suggests to me that fragments were landing nearby.

    I had seen another video that definitely was impacts on the ground. Don’t know why I didn’t posit it here.

  • Steve Garcia

    Ed –

    First of all, did you really mean to say “diffraction of SUNLIGHT”? By the ATMOSPHERE? I am shaking my head if that is what THEY are saying. If you typo-ed that, no problem.

    1. How is SUNLIGHT going to be diffracting when the Sun is behind the tail?

    2. How is sunlight going to be diffracting when there is a more intense light right there to diffract?

    3. How is the atmosphere diffracting on an angle like that – and just HAPPENS to be following along with the meteor?

    At the same time, I am prepared to agree that it IS diffraction, but it IS either the camera lens or windshield.

    In this other “negative” video at , the same types of apparent ejecta occurs.

    Note that there is a 180° opposed streamer each time. ONE shoots out straight ahead of the path, and no opposite one appears, but I think it is hidden in the tail.

    Later on the NW-SE opposing rays change angle. That bothered me until I re-ran it, and I could see that the angle to the camera changed: The meteor was farther to the right in the field of view.

    The rays extend down past the tree line, so it can’t be an atmospheric thing.

    To prove my point here that it cannot be the atmosphere, the second part of the video is another dashcam SW of the object. In this video, after the big flare-up, the rays continue – and one of the vertical rays extends down in FRONT of an oncoming car.

    Case closed. I was wrong. There was no ejecta visible – except for the ablation vapors.

    It IS amazing if a 10 meter object can disintegrate without throwing off pieces.

    Let’s consider that for a moment…

    When CO2-bearing magma comes out of a volcanic vent, the magma is pulverized by the escaping high pressure gases. Can we relate that to this? When this flared did the escaping gasses pulverize almost the entire body(ies)?

    Maybe so.

  • Steve Garcia

    Ed –

    I can’t find which post it is on, but you commented something about Peter Brown in the last couple of days or so.

    At something called, on March 29, Tom quoted the following from ESA:

    At 03:20 GMT on 15 February, a natural object entered the atmosphere and disintegrated in the skies over Chelyabinsk, Russia.

    Extensive video records indicate a northeast to southwest path at a shallow angle of 20* above the horizontal. The entry speed is estimated at around 18 km/s – more than 64 000 km/h.

    According to calculations by Peter Brown at the University of Western Ontario, Canada, drawing on extremely low-frequency sound waves detected by a global network,

    WTF? NE to SW? No no no no no. The bearing was around 279°. The Sun was rising at about 111° – 21° south of due east, and the object’s radiant was to its left (east, as some phrase it). At they calculated and came within an eyelash of matching the Columbians’ path – and it had a bearing of over 282°.

    What is with ESA – or is it Peter Brown? – saying the “Extensive video records indicate a northeast to southwest path” six weeks after the event?

  • Steve Garcia

    Guys, I am beating a dead horse of a different color here:

    From Russia Beyond The Headlines (Rossiyskaya Gazeta). Interfax. 5 March 2013:

    “By 5 March 2013 Interfax had reported that the number of damaged buildings had risen to over 7,200, which included some 6,040 apartment blocks, 293 medical facilities, 718 schools and universities, 100 cultural organizations, and 43 sport facilities, of which only about one and a half percent had not yet been repaired.

    The “damage” was almost entirely broken windows breaking and window trim being blown in. Yes, that one video had a garage door being blown in. And one poorly constructed building had its roof (almost certainly with some snow load on it already) cave in.

    We here never did seem to come to a conclusion whether the big boom was a sonic boom or the burst.

    But that does leave the question: If a large supersonic jet had come in low over Chelyabkinsk what kind of damage would it have done?

    My point eventually gets to this: The damage certainly wasn’t a LOT more than what a sonic boom might have caused. Ergo, the burst shock wave was a WHOLE LOT less than the 500 kts or 524 kts we keep being told. NO sonic boom could be mistaken for a 500kt explosion.

  • Hermann Burchard

    Obviously, the missing disaster that you remark on, is due to the long trail at a shallow angle of 20 degrees, as was discussed earlier on this BBS.

    The blow torch/ blast furnace/ flame thrower/ produced .44 Mt spread out over the length of a 100 km trail, or so.

    However, the main airburst with EM energy flash radiation was near Chelyabinsk or Korkino, but at altitude ~20 km (a .44 Mt nuke at 20 km horizontally would be survivable, I am guessing).

    As posted earlier, .44 Mt is the exact kinetic energy of an 11,000 ton rock at 18 km/sec.

  • Steve Garcia

    I have no disagreement that energy that might have approached .44 Mt was dissipated over the length of the trail between the radiant and the big burst.

    I will also agree that at 20 km the remaining kilotonnage was easily survivable.
    From :

    [Modern Mechanix 1954] “In Hiroshima, more than one-half of the people a mile from ground zero survived the bombing. In Nagasaki, 69 out of every 100 persons at that same distance lived…”

    My latest info is that the height of the big burst was ~23 km. And ground distance was about 35 km from Chelyabinsk. That is line-of-sight about 42 km.

    Korkino was only 7km ground and 24 km line-of-sight, and no real damage.

  • E.P. Grondine

    Hi Steve –

    If you search youtube for “NOVA russian meteor strike” it will likely lead you to copies of the NOVA special on Chelysbinsk.

    It is well worth watching.

  • The Earth’s atmosphere really does protect us from lots of stuff….

    Cool stuff up at Space Daily dot com including:

    Comet to Make Close Flyby of Red Planet in October 2014

    and one you should love Steve G about simulation and modeling of early solar system (I’m just kidding man, take a deep breath…)

    The mathematical method for simulating the evolution of the solar system has been improved

    If either of these are reposts I’m sorry without much time to read Tusk while second child shattered elbow and I had long business travel. My usual browsing routine is Space Daily first, to troll for good links to post here. When time is very limited, I don’t review Tusk first to avoid redundant coverage….


  • For those who haven’t seen it yet the full PBS NOVA episode is on the PBS video website. See ‘Meteor Strike’

  • George Howard

    Thanks, D.

  • Hermann Burchard

    The 3/27/2013 NOVA video outdated a bit. Pretty much the same story as told on Tusk.

    The trail is a moving mushroom cloud, says the Bos man. Ergo, the longitudinal center split is hollow stem of mushroom, stretched out.

    Most interesting part, infra sound frequency f tells energy E. Least f –> largest E. Needs formula:

    E = c * 1/ f^a, c,a=const ???

    Wikipedia has latest: Main air burst lasted 5 sec, visible spectrum radiant energy alone was .09 Mt. At 18 km/sec the main burst is spread over 90 km.

    Garage door blow down all from pressure wave of powerful blast, no sonic boom to speak off IMHO: Is there even a clear distinction?

  • E.P. Grondine


    B. does not know what he is talking about, and dealing with his nonsense is a waste of time.

    Peter Brown is presenting (has presented) his latest analysis at the current conference in Arizona. Holsapple and Lawrence Livermore are at the conference as well, as well as DoD.

    The only people not there are those known to be from the “comets and comet fragments do hit” school. But that is the kind of petty BS I learned to expect from Morrison years ago.

    Despite M.’s efforts, there are people at thix conference from the comets and comet5 fragments do hit and have hit school; its simply that M. does not know who they are, and I want to keep it that way.

    This conference is being streamed.

  • E.P. Grondine

    PS –

    The current division between impact geologists and the obervor community is entirely M.’s doing, though he’s had help in doing this.

    For me, there is nothing more contemptable than preventing data from interfering with your theories.

  • More goodies at Space Daily dot com:

    Supernova may have left biological ‘signature’ in ancient Earth

    Shocking. Unless you read Tusk.


  • Dennis that PBS video link to Meteor Strike is a gold mine.

    Good shock modeling of the cook-off and subsequent propagation down to surface. In that sim you can see the convection on the order of 5k meters or so upward of the plume in the time it takes the (faster) shock to reach the surface much further beneath. Of course its only a model.

    The vertical version of the similar impact model shows the convective plume reversing direction and traveling back up the entry “tube”, and larger overpressure at surface. Those hydrocode guys, I think they may be onto something with that “equation-of-state” business….

    Also interesting that a stony asteroid would still drop scorched pebbles out of the fireball. At some level the process eventually loses speed, and so thermal consumption of some portion of mass never happens, however relatively small that remaining portion is. Bunch of little pieces.

    This to me implies signature of impactor to everywhere within the full volumetric limits of the fireball envelop and even beyond, during the fireball process and short time subsequent. There will be a test on this material.

    Still the best line from above linked article:

    “The sediment core contained the isotope iron-60, which does not form on Earth, and scientists said the source was likely a supernova in our cosmic neighborhood, the journal Nature reported Monday.”

    That’s WAY out there. Really. That places the Tusk firmly in the mainstream, getting down to pure statistical probability of supernova dust vs. impact tweaking of everything from continental bio speciation, to hemispheric climate and possibly longer term (1400 yr) global climate. I’m just sayin’.

    Yes it would have to be a big old bunch of barge loads of brew haa raining down. Tough to imagine no surface signature at all, though, even if in secondary proxies only, due to mixing of the (albeit extremely faint) impactor signature with that of the atmosphere/surface during production of effluent from whatever the impact process. Thats the thing, we’re not sure of the process, other than it involves unEarthly high temperatures. Proxy ID then becomes the pursuit…..

    WHen I hear about Iron 60 in concentration, I wonder if Earth may not have produced it one time? Or could our own Sun have belched some out (I know Iron is the death nell for a star so ours not yet near that phase)


  • Steve Garcia

    Hermann –

    The garage door thing – you find out early on in real world mechanical engineering that it takes very little pressure on an entire large area like a garage door to be able to push it in. Especially when the force is delivered as a quick impulse. That can multiply the effect of the force by a magnitude or more. The shorter the impulse, the greater the magnification of the force.

  • E.P. Grondine

    It looks to me like several people here do not understand the difference between a fireball and a bolide.

  • George Howard

    Ed, quit the smartest guy in the room schtick.

  • Steve Garcia

    Oy vey.

    Ed, thanks for the YouTube suggestion. I was able to watch the NOVA meteor episode.

    However, I learned basically nothing from watching it that I didn’t already know, except that Boslough did his precise mapping of the path. That was basically sound science. (But why weren’t other scientists also doing that? We should have at least a handful of such studies to compare to each other, narrowing down the final path even more.)

    But I saw some GLARING errors and inconsistencies.

    Peter Brown [08:25] was pulling numbers out of his head (“My first estimate was about 40 or 50 kilotons, based on just sort of an estimate”) – all that proved to be terrifically wrong – even before he had gotten any evidence upon which to base anything on. BAD science. Good honesty to admit it on camera, but bad science. It should have been edited out – by Brown himself if given a chance to review what he had said. It shows how when even “those in the know” jump to conclusions without evidence, they can be so far off as to be no better than guesses by people off the street using their wet thumbs up in the air. So the next time you hear a scientist pontificate on some phenomenon without looking into it, remember Peter Brown and his hip shooting on this event. Pulling numbers out of one’s butt is exactly that – no matter HOW “in the know” a person is. When he could be off by an ENTIRE MAGNITUDE, Mother of God, that is bad.

    He then had the balls to actually say “We wanted to give people an informed idea” from “those with past experience,” when he and everyone involved say over and over again, “this was unprecedented” and “this is a once in a lifetime” and “this was the biggest in one hundred years.” How exactly does any of that translate into past experience?

    More later. I was VERY underwhelmed by the scientists on the show. Typical NOVA – aiming for the 4th graders.

  • E.P. Grondine

    Hi George –

    “Fireball” and “bolide” are fundamental terms in impact science. While I am no longer the smartest guy in the room, understanding those words is essential in this field of science.

  • Trent Telenko

    This link gives a working definition of “Fireball” versus “Bolide.”

    I broke up the wall o’ text for easier reading.


    — A ‘fireball’ is a brighter-than-usual meteor. The International Astronomical Union defines a fireball as “a meteor brighter than any of the planets” (magnitude −4 or greater).[21]

    The International Meteor Organization (an amateur organization that studies meteors) has a more rigid definition.

    — It defines a fireball as a meteor that would have a magnitude of −3 or brighter if seen at zenith. This definition corrects for the greater distance between an observer and a meteor near the horizon. For example, a meteor of magnitude −1 at 5 degrees above the horizon would be classified as a fireball because if the observer had been directly below the meteor it would have appeared as magnitude −6.[22] For 2012 there were 2126 fireballs recorded at the American Meteor Society.[23] There are probably more than 500,000 fireballs a year,[24] but most will go unnoticed because most will occur over the ocean and half will occur during the daytime.

    — Fireballs reaching magnitude −14 or brighter are called bolides.[25] The IAU has no official definition of “bolide”, and generally considers the term synonymous with “fireball”. Astronomers often use “bolide” to identify an exceptionally bright fireball, particularly one that explodes (sometimes called a detonating fireball). It may also be used to mean a fireball which creates audible sounds.

    — In the late twentieth century, bolide has also come to mean any object that hits the Earth and explodes, with no regard to its composition (asteroid or comet).[26] The word bolide comes from the Greek βολίς (bolis) [27] which can mean a missile or to flash. If the magnitude of a bolide reaches −17 or brighter it is known as a superbolide.[25][28]

    What I found interesting at the same text-link was the following table

    Reported Fireballs[20]
    Year #Fireballs
    2012 2126
    2011 1631
    2010 951
    2009 694
    2008 726

    …which confirms my observation that more of these events are being reported, for whatever reason.

  • Steve Garcia

    Trent –

    Good stuff.

    There is a glossary tab at the top of the page. Right nmow it has only one comment/glossary definition.

    It might actually be a good idea here to take your comment and paste in into a comment there.

    I’d never gone to that link. Perhaps we should all add items to that when we run across definitive stuff. (duh…)

  • E.P. Grondine

    Hi TT –,2007/

    You may want to check the meteorite list archive for the discussions of those definitions.

    The Chelyabinsk videos have pretty much brought those discussions and the confusion to an end.

    Note carefully the light output levels.

  • Steve Garcia

    Ed –

    Which meteor list archive and discussion are you talking about. You keep tossing out references without giving links, so it is impossible to follow up on.

  • E.P. Grondine

    Hi Steve –

    Google “meteorite list archive” “bolide” and “fireball”.

    I get so many questions that I casn not provide you personally with more than that right now. I may have archived those discussions myself on my home machine, but if so it will only be possible to send them to you later, if you are real nice and polite between now and then, and I have time to retrieve them later.

    If your income and livelyhood depend on the knowing the difference between a bolide and a fireball, then you know it. Strewn fields are not a matter of recreation or “simple” curiousity for some people.

  • Trent Telenko

    This is another quick link to go too —

  • Trent Telenko

    Here is another important link —

    It is the University of Purdue’s >Impact Earth!< Impact calcualtor.

    Now anyone can play at bolide yield what ifs.

  • Trent Telenko

    I saw this over on Instapundit:

    The meteor that injured more than 1,500 people when it exploded and showered debris over Russia in February may have had a close shave with the Sun earlier, researchers said.

    A study of its composition showed the space rock had undergone “intensive melting” before entering Earth’s atmosphere and streaking over the central Russia’s Chelyabinsk region in a blinding fireball, they said in a statement.

    This “almost certainly” points to a near-miss with the Sun, or a collision with another body in the solar system, possibly a planet or asteroid, study co-author Victor Sharygin from the Russian Academy of Sciences’ Institute of Geology and Mineralogy said.

    The findings were presented at the Goldschmidt geochemistry conference in Florence, Italy.

    Does this affect any of the earlier findings on the trajectory of the Russian fireball?

  • Steve Garcia

    Like I said:

    The orbit they told the world was on not so far different from the Earth’s, one that the Apollos have. Those orbits are nearly circular. If it grazed the Sun, then by definition it had to have a highly elliptical orbit. You can’t have both.

    Such an orbit could not hit the Earth on its leading side “on its windshield, near the top” – which the Chebarkul object did. It was impossible to match the final path and the earlier orbit.

    It is, of course, possible that they are misreading the evidence now. But I am certain that they would know that the physical evidence they are presenting contradicts the earlier orbit, so they would have known they needed to be extra sure of their evidence before they published.

    This evidence trumps that orbit.

  • I have to research the Apollos, but I can tell you that orbits can be changed radically over time by resonances with planets and long term perturbation.

    The key to remember with sun or iting objects is the immense time over which these objects are exposed to the effects in question – small forces but huge integration times add to significant dynamic change. Tough to comprehend the time scales over which these bodies are exposed.

    Secular perturbation can evolve an orbit into resosnance with a planet (2:1 w Jupiter being a common example), at which point crazy things can happen very quickly in terms of orbit transformation, with energy transfer happening over an extremely short period, even one or just a few orbits.

    That can throw a heliocentric orbit straight out of the solar system, or drop it straight at the sun by giving it or taking away from it the right quantity of orbital mechanical energy.

    So circular orbits can end up highly eccentric. It’s nuts but its been studied for a long time, and even has analogs in stability of matter, particle physics.

    Also remember that it could have encountered the Sun many times and/or an immensely long time ago.


    When it appeared to come nearly out of the Sun’s direction, that observation was an apparent direction, a combined result of both the bolide’s motion in space and of Earth’s. Earth alone moves about 10 of its own diameters through space every hour. This always confuses the observation. Lots of relative motion and a lack of local inertial reference.

    I’m not trying to say anyone’s right or wrong, just throwing out tidbits of my own experirnce from my Comsat fleet ops days as an or it analyst and from my work with the mission planners on the Mars Observer interplanetary mapping spacecraft.


  • Steve Garcia

    Thanks, TH –

    Yeah, the Sun grazing could have been a long, long time ago. Are there any tests to gauge that by?

    The bit about “appearing” to come out of the Sun’s direction – there really was not “appearing” about it. It did. I think your point was that even though its final approach came from Sun-ward, its previous orbit could have been far different. No argument there. But for its final flight path to be coming from where it did, the center of gravity of the Earth had to have put it on a Great Circle path or damned near it – meaning the landing point, the initial sighting and the center of Earth had to define a plane. And that plane ain’t NOWHERE near coming from the Apollos, from behind the Earth’s track.

    NO ONE that I’ve seen has yet tied the intitial orbit given by the S American guys to the final path. I don’t remember all the details now (they are posted here somewhere), but I’ve said this since day one, and no one has listened to me. I don’t give a crap anymore, but the orbits given to the world are wrong. Period.

  • Trent Telenko

    Physicist Mark Boslough of the Sandia National Laboratories is revising and extending is remarks on Chelyabinsk.


    But meteors explode in a very different way than a typical nuclear bomb, says physicist Mark Boslough of the Sandia National Laboratories, who studies asteroid impacts and is presenting a talk today about the Chelyabinsk event at the American Astronomical Society’s 2013 Division for Planetary Science meeting in Denver.

    “When an asteroid explodes, its momentum is conserved and that explosion continues down toward the Earth,” Boslough said.

    For that reason, the people who live in Chelyabinsk explosion are very lucky to be alive, he added. If the bollide had come into the atmosphere at a less steep angle, its blast would have been aimed right at the ground, likely doing much more damage.

    That an airburst continues traveling in the same direction as a meteorite was only appreciated starting in the 1990s, particularly after the impact of Shoemaker-Levy 9 on Jupiter.

  • Steve Garcia

    The Russian meteor wsa in the news again recently.

    On October 16, divers found the biggest piece of the meteor, weighing 670kg, at the bottom of Lake Chebarkul. Strange how long it took…

    And four days ago there was this:

    “It deposited much less material than expected,” [Peter] Jenniskens [NASA Ames] told “That’s similar to what was seen with Tunguska, where nothing from the impactor survived.”

    A question I have not heard is:

    If the Chelyabinsk meteor fell about 74km away from the big explosion, had anyone ever looked downfield that far for a remnant of Tunguska? Yes, in 2013 it blew up much higher, so the distance was more. But it should be some sort of guide for possibly finding a Tunguska remnant, after all these years.

  • Trent Telenko

    Found via Instapundit:

    Russian Meteor, from Birth to Fiery Death: An Asteroid’s Story
    By Mike Wall, Senior Writer |
    December 10, 2013 07:20pm ET

    SAN FRANCISCO — The asteroid that exploded over Russia earlier this year died as it had lived — in a welter of chaos and violence.

    Scientists have pieced together the history of the space rock that slammed into the atmosphere over the Russian city of Chelyabinsk on Feb. 15, creating a shock wave that injured 1,200 people. It’s a long, convoluted tale that picks up just after the solar system started coming together 4.56 billion years ago.

    Molten droplets that found their way into the Chelyabinsk object formed within the first four million years of solar system history, David Kring of the Lunar and Planetary Institute in Houston said here Monday (Dec. 9) at the annual meeting of the American Geophysical Union. [Photos: Russian Meteor Explosion of Feb. 15, 2013]

    Over the next 10 million years, these tiny pieces, along with generous helpings of dust, coalesced into an asteroid on the order of 60 miles (100 kilometers) wide. Textures spotted within pieces of the Chelyabinsk asteroid recovered here on Earth reveal that the rock was likely once buried several kilometers beneath the surface of this larger object, which scientists call the LL chondrite parent body, Kring added.

    Further, analysis of “shock veins” within Chelyabinsk meteorites indicate that the parent body suffered a major impact about 125 million years after the solar system started forming.

    And the hits kept on coming, with the parent body absorbing strike after strike between 4.3 billion and 3.8 billion years ago, Kring said. (Earth and other planets in the inner solar system were also pummeled during this period, which is known as the “late heavy bombardment.”)

    The LL chondrite parent body apparently then got a break, and was left alone to lick its wounds for a few billion years. But meteorite fragments record evidence of two more large impacts in the last 500 million years, with one of them coming between 30 million and 25 million years ago.

    The next big event for the parent body had consequences for people on Earth as well.

    “The meteoroid then encountered a gravitational resonance in the asteroid belt, and that altered its orbit,” Kring said. “So at that point, it moved from being a main-belt asteroid to being a near-Earth asteroid.”

    Work published just a few months ago indicates that the Chelyabinsk asteroid was exposed to space just 1.2 million years ago, suggesting that yet another impact occurred around that time, Kring added.

    This collision perhaps finalized the size of the space rock, which is thought to have measured about 65 feet (20 meters) wide when it entered Earth’s atmosphere.

    “And finally, of course, we have one more collisional event, on Feb. 15, 2013,” Kring said.

    While the Chelyabinsk asteroid met its end that day, other fragments of the LL chondrite still exist out in the depths of space. One such chunk is the 1,770-foot-long (540 m) asteroid Itokawa, which Japan’s Hayabusa spacecraft visited in 2005, gathering samples that were returned to Earth five years later.