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Could Another Chelyabinsk-Scale Meteor Sneak Up on Us?

The views expressed are those of the author and are not necessarily those of Scientific American.


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Asteroid orbit before impact

Credit: ESA

When a 17-meter asteroid barreled into Earth’s atmosphere over central Russia on February 15, releasing a powerful shock wave that injured more than 1,000 people, many observers wondered how such a momentous event could arrive unheralded. The fact is, the object that exploded in a fireball over Chelyabinsk, releasing hundreds of kilotons of energy, was small potatoes. There may be millions of comparably sized objects in the inner solar system, only a small fraction of which have been discovered. The searches to date have been focused on tracking much larger dino-killers and other potentially catastrophic asteroids and comets—those objects larger than about one kilometer. So the door has been open to unpleasant but ultimately survivable asteroid surprises.

Several new and forthcoming projects will amass reams of new data about the near-Earth asteroid (NEA) population, but a comprehensive catalogue of Chelyabinsk-scale objects remains beyond the technological horizon. The asteroids are too numerous, and too faint, to be systematically tracked. Below is a rundown of some of the best tools that researchers currently have for asteroid detection and defense:

The Catalina Sky Survey discovers about 600 NEAs every year from telescope sites in Arizona and Australia. Since the mid-2000s Catalina has been the leading NEA-detection project in existence, helping NASA to reach its goal of cataloguing 90 percent of all near-Earth asteroids larger than one kilometer in diameter. But its pace of discovery is too slow to make a significant dent in the much larger populations of smaller objects. Near-Earth asteroids larger than 100 meters likely number in the tens of thousands, whereas nearby asteroids 10 meters and up number in the millions.

The first of four planned Pan-STARRS telescopes in Hawaii recently came online and is now the second-leading NEA search in existence, in terms of objects detected per year. In 2012, its second full year of operation, Pan-STARRS discovered 251 near-Earth asteroids, according to NASA statistics. It should help discover many asteroids with diameters in the hundreds of meters, but the bulk of smaller objects will remain out of reach.

Estimated asteroid discoveries with LSST

Projected near-Earth object discoveries with LSST. Credit: LSST

The Large Synoptic Survey Telescope, which should come online toward the end of the decade in Chile, will be a survey telescope of astonishing capability. The 8.4-meter telescope, equipped with a 3-gigapixel digital camera, will scan the skies every few nights to pick up moving objects or transient events. But even the LSST will have trouble picking up asteroids as small as the one that impacted the atmosphere over Russia last week. It will take decades of work (right) before the LSST has catalogued the vast majority of much larger objects—those 140 meters and up—thereby meeting NASA’s next asteroid-detection goal.

If an asteroid were detected years in advance, the world’s governments could take corrective action—detonating, nudging or tugging a hazardous object onto a safer orbit. The Asteroid Terrestrial-Impact Last Alert System (ATLAS) has a much simpler goal: detect asteroids just weeks before impact so as to warn or evacuate the threatened areas. ATLAS, which will comprise several small telescopes in Hawaii, is in development with financial assistance from NASA and may be operational by 2015. Its planners estimate that a 50-meter “city killer” could be detected one week ahead of impact.

The nonprofit B612 Foundation recently unveiled its plans to build the Sentinel Space Telescope, an asteroid spotter that would scan the inner solar system in the infrared from an orbit similar to the planet Venus. If the foundation can raise the hundreds of millions of dollars needed to build Sentinel, the spacecraft would launch in 2018 and make quick work of the truly dangerous asteroids out there. The Sentinel mission design calls for a telescope that would catalogue 90 percent of NEAs bigger than 140 meters over its 6.5-year mission. According to a recent statement from B612, the Sentinel would also spot more than half of the currently undiscovered asteroids larger than about 50 meters.

With limited resources, asteroid spotters have naturally focused on the largest asteroids that could cause the most mayhem. But the smaller, more frequent arrivals to our planet are likely to remain unpredictable for the foreseeable future. On the bright side, no deaths have been reported as a result of the Chelyabinsk incident, and the odds of the next significant meteor exploding over such a populous area are slim.

And, fortunately, impacts on the scale of the Chelyabinsk meteor are predicted to occur only once a century. So perhaps humankind will have figured out better techniques for discovery and tracking by the time the next one comes our way.

About the Author: John Matson is an associate editor at Scientific American focusing on space, physics and mathematics. Follow on Twitter @jmtsn.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. karenalcott 3:15 pm 02/20/2013

    We as a species need to do this right away, whatever we do to protect the enviroment is a moot point if it all gets wiped out anyway. We need to start thinking about whole planet threats as a whole species who are at the top of our planet’s food chain. We are the responsible parties, because we are the only ones who can see the danger before it is too late. Sitting around with blinders on, because God will save us, it’s our destiny to rule the galaxy and we’re just too darned exceptional to go out like that anyhow, just ain’t gonna cut it.

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  2. 2. Rev.Corvette 4:04 pm 02/20/2013

    I wholeheartedly agree with karenalcott’s comment… and ask What Research is of Greater Importance than the Early Discovery and Viable Deflection of Earth Impacting Asteroids, Meteors and the like?

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  3. 3. Acoyauh2 5:23 pm 02/20/2013

    “So perhaps humankind will have figured out better techniques for discovery and tracking by the time the next one comes our way.”

    I hate to rain on your parade, but “once every hundred years” does not mean we’re safe for another century, it’s just the probability we have of being hit. There’s nothing to guarantee we won’t see three others behind this meteor, or a bigger one, or in fact never be hit again.
    No, we don’t have the time and can’t afford the luxury of (again) leaving it to future generations to figure it out and deal with it.

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  4. 4. AntonioMario 3:17 pm 02/21/2013

    Acoyahu2, I agree with you. In fact, given that is very improbable that we observe all events of the magnitude of the russian meteor of last week, the actual rate of such events is probably higher by a factor of 3-5 or so (I seem to recall a scientist mention a factor of 10). This means that once every 25yrs or so is likely to be a better estimate for the frequency of occurrence.

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  5. 5. vagnry 3:20 pm 02/21/2013

    Off course (off does not miss an f)

    This is one (when we are thinking of minor asteroids) of the least dangers to humanity possible, since Tunguska in 1908 (which didn’t kill anyone, as it fell in an unpopulated area), no person has been killed, a few have been hit, but possibly a dog and some livestock have died.

    http://en.wikipedia.org/wiki/Meteorite

    Compared to gunshot killings, road accidents, global warming, coal production and use, hurricanes etc, etc, this is not an issue worth any taxpayers money.

    If any money had to be spent on this, I would vote for the ATLAS project. When we are able to detect small meteorites, and determine where they fall a week before impact, we could evacuate the area, and come back and clear the debris afterwards, safe and cheap.

    Just like what we do when another natural disaster is about to strike, people still live on vulcans, in New Orleans…

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  6. 6. CharlieinNeedham 3:27 pm 02/21/2013

    Strike while the iron is hot.

    And there has been no hotter time than now to fabricate a purpose for a manned space program.

    So let’s get Bruce Willis and get after those asteroids before THEY get US!

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  7. 7. jack.123 10:23 pm 02/21/2013

    When it comes to odds,anything can happen.Waiting is not an option,we need to do what is needed now even if it costs 100 billion dollars or more.We have had our warning,there is no reason the next big event couldn’t happen tomorrow.The president needs to act now and use executive privilege if congress doesn’t act as well.It doesn’t matter if no other nation acts,we need to take the lead on this.The future of humanity depends on it.Of the many things that can bring an end to our species this is one that we can and must control.A 500 meter event above one of any major economic centers around the world can start a path that at the least would cause a world wide depression and at worst a world war.That is why prevention would be the cheapest path to follow.

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  8. 8. patrick 6:16 am 02/22/2013

    Could Another Chelyabinsk-Scale Meteor Sneak up on us ?
    A most challenging question,that requires deep thought and expertise ! a little luck to crack the cosmic code at BASE..
    The Meteor or Asteriod might be composed of an unknown class,of Celestial Bodies, probably in the Negative Range,Reservation’s— as the Russians initially claimed, that its approx: size is about, ” one cubic meter ” .

    Therefore we cannot rule out the possibility, that the One Cubic Meter, Iron Block core ” Asteriod “, with such an immense energy content, is composed of ” NEGATIVE MASS”originating from the GRAVITO-MAGNETIC PHASE SPACE SLICE OF 4.66 Degrees approx., following a convergence type XXX gravito-magnetic phase -space track, at that specific fixed moment of “TIME & LOCATION SPOT”,when Celestial Bodies were in” Synchronised Dynamical Phase Lock ” which if it penetrates our Electro-magnetic world, SHORT-CIRCUIT’S,and impacted with the Signature of “IMPLOSION” on impact

    In such a scenerio, the debris will not exist,as it could have mirror-imaged a Reverse slew of unknown particles.
    The powerful thrust as on the Video and media reports, confirms and thats what the eyewitness, photographs ,and templates analysis, display so vividly,—- an ” IMPLOSION ” and SOUND PHONON’s at the speed of light “RESONANCE” —SPECIFICALLY IN THIS CASE ! CHAOTIC CHAOS over a vast area of the Russian Region.

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  9. 9. CharlieinNeedham 10:02 am 02/22/2013

    Quick.

    Let’s expand our anti-ballistic missile program to include the capability to shoot down meteors.

    Forget about the current trillion dollar deficits – cut needless medicare spending or NIH grants to pursue this “vital need”.

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  10. 10. jwmeritt 3:48 pm 02/22/2013

    To me, “sneak up” attributes intention – which isn’t there. Now, if the question is moderately changed to “approach unannounced”, I would guess “yes” Especially dark and non-reflective (cordates?) cold (it has been in 4 degree K space a long time.

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  11. 11. jwmeritt 3:50 pm 02/22/2013

    “anti-ballistic missile program” ummmm, there is a bit of difference in the delta-V required for near-earth intercept of a relatively fragile object and deep space intercept of a hunk of rock. Different problem will require a different solution.

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  12. 12. peterbrm 6:13 am 02/25/2013

    vagnry claims that the Tunguska explosion in 1908 did not kill anyone, as it fell in an unpopulated area. I saw a documentary where investigators visited a trading outpost/settlement, which was outside the main blast area, but still suffered damage from the shock wave. Records indicate that the surrounding area was a sparsely populated by Russian trappers , and more densely populated by indigenous inhabitants. Presumably the Tsarist authorities were not interested in whether the explosion killed any “down and out” trappers, or in identifying which groups of “natives” had been in the blast zone. I suppose the authorities may also have wanted to avoid the risk of public panic by miss reporting casualties.

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  13. 13. stevewaclo 7:46 pm 02/27/2013

    Every time I blunder upon yet another “killer asteroid” story, I go to my Open Office files and dredge up this standard response:

    At the risk of being glib and facile, not necessarily in that order, I say let us all wrap ourselves in the warm, comforting mantle of geological time and get on with solutions for issues that are a much more immediate threat to our species’ survival”

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  14. 14. meh_met 4:10 am 02/28/2013

    there are other solutions for the 1908 event. one i recall is a “kimberlite” type explosion from the crust of the earth upward expalining fully the woods away from explosion center(s).the second, which i read in Nature, is a mini-black hole passage thru earth. i give some credit especially to the first solution.
    me.ozel

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