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Space Earth

Asteroid Impacts Bigger Risk Than Thought 172

Posted by Unknown Lamer
from the just-build-space-lasers dept.
Rambo Tribble (1273454) writes "The B612 Foundation, a U.S.-based nuclear test monitoring group, has disclosed that their acoustic sensors show asteroid impacts to be much more common than previously thought. Between 2000 and 2013 their infrasound system detected 26 major explosions due to asteroid strikes. The impacts were gauged at energies of 1 to 600 kilotons, compared to 45 kilotons for 1945 Hiroshima bomb."
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Asteroid Impacts Bigger Risk Than Thought

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  • by Anonymous Coward on Wednesday April 23, 2014 @11:11AM (#46824427)

    The B612 Foundation [b612foundation.org] is a private venture dedicated to finding NEOs that will impact the Earth. They used nuclear test monitoring equipment to find the explosions resulting from asteroid impacts.

  • 1-600 kilotons (Score:5, Informative)

    by Arancaytar (966377) <arancaytar.ilyaran@gmail.com> on Wednesday April 23, 2014 @11:15AM (#46824455) Homepage

    8/25/2000 (1-10 kilotons) NORTH PACIFIC OCEAN
    4/23/2001 (1-10 kilotons) NORTH PACIFIC OCEAN
    3/9/2002 (1-10 kilotons) NORTH PACIFIC OCEAN
    8/9/2006 (1-10 kilotons) INDIAN OCEAN
    9/2/2006 (1-10 kilotons) INDIAN OCEAN
    10/2/2006 (1-10 kilotons) ARABIAN SEA
    12/9/2006 (10-20 kilotons) EGYPT
    9/22/2007 (1-10 kilotons) INDIAN OCEAN
    12/26/2007 (1-10 kilotons) SOUTH PACIFIC OCEAN
    10/7/2008 (1-10 kilotons) SUDAN
    10/8/2009 (>20 kilotons) SOUTH SULAWESI, INDONESIA
    9/3/2010 (10-20 kilotons) SOUTH PACIFIC OCEAN
    12/25/2010 (1-10 kilotons) TASMAN SEA
    4/22/2012 (1-10 kilotons) CALIFORNIA, USA
    2/15/2013 (>20 kilotons) CHELYABINSK, OBLAST, RUSSIA
    4/21/2013 (1-10 kilotons) SANTIAGO DEL ESTERO, ARGENTINA
    4/30/2013 (10-20 kilotons) NORTH ATLANTIC OCEAN

    yyeeeah, those are technically all between 1-600 kilotons.

    Also, between 1 kiloton and 600 gigatons.

  • Not impressed (Score:2, Informative)

    by Anonymous Coward on Wednesday April 23, 2014 @11:17AM (#46824493)

    First, the Hiroshima bomb was 13 Kilotons, not 45. Nagasaki was roughly 20 Kilotons.

  • Re:How much energy? (Score:1, Informative)

    by Anonymous Coward on Wednesday April 23, 2014 @11:19AM (#46824537)

    Not a lot. While 600kilotons of TNT on a local scale is an enormous amount of energy. That amount of energy spread over the world as heat is almost unmeasureable especially compared to other more major factors such as global warming.

  • by MozeeToby (1163751) on Wednesday April 23, 2014 @11:23AM (#46824609)

    About 3% of the planets land area is considered "urban". Taking into account the oceans that makes for right around 1% of the total surface area of the planet. That means that any given year there's about a 2% chance of an asteroid explosion happening over a major population area. That means a 1/3 chance of a significant (greater than 1 kiloton) explosion over an urban area over a 50 year time span. That's not crazy high, and most of those will occur at high altitudes, but it's certainly not once in 5000 years.

  • Re:How much energy? (Score:4, Informative)

    by by (1706743) (1706744) on Wednesday April 23, 2014 @11:27AM (#46824661)
    600 kilotons TNT is about 2.5e15 J. In comparison, the sunlight incident on the Earth is around 174 petawatts, meaning it takes roughly 20 milliseconds for that much solar energy to be absorbed (clouds, oceans and land masses) by the Earth (taking into account the ~30% reflected power). In comparison, the total world annual energy consumption is around 5e20 J. So, I wouldn't be too worried about added heat due to asteroids.

    Sources:
    https://www.google.com/search?... [google.com]
    http://en.wikipedia.org/wiki/O... [wikipedia.org]
    http://en.wikipedia.org/wiki/S... [wikipedia.org]
  • by Shakrai (717556) * on Wednesday April 23, 2014 @11:29AM (#46824691) Journal

    Little Boy clocked in at ~15 kilotons, not 45 kilotons per TFS. Fat Man was ~21kilotons, though it was dropped off target and ended up doing less damage than Little Boy.

  • by ThreeKelvin (2024342) on Wednesday April 23, 2014 @11:48AM (#46824907)

    Your math is off. If your numbers are correct, the risk of having at least one meteor over an urban area during those 50 years is:

    P(N>1) = 1-P(N=0) = 1-(1-0.3*0.03)^100 = 60%

  • by EngineeringStudent (3003337) on Wednesday April 23, 2014 @12:10PM (#46825131)

    We don't have enough history to gauge what actually has happened over time, so we have to estimate.
    We approximate by finding big rocks or chemistry on earth, looking at craters on the moon, or this.

    In all these cases we are using the small but frequent to infer the distribution of big but hugely problematic events. Our best answer the question about the likelihood of a killer impact is grossly changed if this tail is changed.

    Think about it like floods. We ask how likely a 10,000 year flood is going to happen next year. We have ~100 years of rainfall data. We fit it to a distribution that is appropriate and then use those fit parameters to make a best guess. If our rain gauge was only measuring half the rain, we might under-estimate the actual risk by a factor of 10x or 20x.

    There is good correlation between "killer impacts" and location of the sun in the galaxy (yes it moves around). We are starting to enter a higher risk region (transition to edge of arm) and perhaps the fundamental distribution is changing. In that case the history of craters on the moon or other might not be meaningful indicator of the near future.

    Considering this I think good tracking is not a bad idea and should be thought out well and properly considered.

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