RE: killer Asteroid

Discussion in 'Astronomy, Exobiology, & Cosmology' started by blobrana, Feb 25, 2003.

  1. blobrana Registered Senior Member

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  3. Jaxom Tau Zero Registered Senior Member

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    What bothers me is the consistant way an observation like this is used to sell stories. Big headline "Earth Doomed", "Imminent Collision", "Doomsday Rock"...and then at the end the unemphasized mention that the chances are low, more observations are needed to be sure of the path, and it won't be back for generations.

    What's the problem? It's more of crying wolf...it's desensifying the public to a serious matter. When funding for NEO discovery and development of techniques to stop them is brought up these days, after all the bad movies and misrepresented facts, the public shrugs the denial as no big loss, since the papers always say at the end that isn't not a problem for this generation, or the end of the movie showed a laser on a jet firing at the last minute, no big problem there. Anything space oriented is seen as a frivolous waste of resources...give the money to the military, that's much more important. So what that the military budget increase is probably as big as the total devoted monies to space. Defense is important, you say....we have to have the tools to protect our nation and the free world, right? Well, doesn't this qualify as a threat to our well being, and to life as we know it? Make the military budget pay for NEO research then!

    I predict one day...it could be in the far future, or tomorrow...we will discover something heading this way. Most people will look at the headlines, and say yeah, read that before. Or maybe it'll be hushed up, to prevent riots. But at any rate, that day will come. We will either be ready enough to 1) see it coming in time, and 2) do something about it....or not. And if not...then that generation and any others that would have been after it were killed by this generation's inaction and lack of caring.

    Objects do hit the earth. That's a simple fact. We're the first species to be able to do something about it...so what are we doing? Not a lot...

    Lecture/rant over...

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  5. Gifted World Wanderer Registered Senior Member

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    We build bigger bombs.
     
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  7. rushguy1 Registered Member

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    Look out

    Niribu? Planet-X? What is it that NASA has pictures of as of 2/17/03? Looks like a comet twice the size of Earth. http://www.rense.com/general35/COMET.HTM Check there or go to the Solar and Heliopsherc Observatory SOHO website.
    Passing withing 5 million miles of the Sun is different.

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  8. foadi Registered Senior Member

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    Actually, a 1 mile wide asteriod colliding with earth would create an explosion equivalent to somewhere in the neighborhood of 500 million kilotons on TNT. The human race does not make bombs anywhere near that big.

    - foadi(se) de la Ter-Rani
     
    Last edited: Feb 26, 2003
  9. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Jaxom,

    Possibly some day when a real collision is eminent people will read the headlines go "ya right" then read the fine print "1/5 chance of collision in 6 months" then they will start screaming like the sky was falling(which it is likely in this situation)

    I believe nukes are the best way to deflect a asteroid or comet: we send up volley after volley, blow them up right up against the asteroid or comet to change its trajectory. we would need a least 5 years warning to send a probe up to check structural integrity and determine proper distance for the nukes to blow and time for us to prepare and launch a lot of nukes.

    foadi,

    The site claims two different impact values: "million tons of TNT" (1 megaton) and "44,800 megatons" for 1950 DA. I would go with the latter of 44.8 Gigatons... so then no we don't make bombs in that range: the larges production nuclear bomb was 59 megatons
     
    Last edited: Feb 26, 2003
  10. blobrana Registered Senior Member

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    sry,
    fixed now...

    tnx.
     
  11. foadi Registered Senior Member

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    Tsar Bomba yeild was 59 megatons? I was under the impression that it only yeilded 50 megatons(Though was designed to yeild 100 megatons of TNT). Have a link to where you got the information?

    - foadi(se) de la Ter-Rani
     
  12. ElectricFetus Sanity going, going, gone Valued Senior Member

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    "Trinity and Beyond" the video bought off Discovery... or was it TLC I get those confused?
     
  13. foadi Registered Senior Member

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    TLC, I think. I remember watching that.
     
  14. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Blobrana thats your site?!? Very nice!
    You change it to:
    "The collision would smash millions of tons of TNT into the Earth and could wipe out a large city, trigger widespread fires and tidal waves."

    the change I would advice is:

    "The collision would be as explosive as billions of tons worth in TNT and would cause a level of destruction probably not seen since the end of the dinosaurs."

    This way it just as accurate but much more ominous and scary.
     
  15. foadi Registered Senior Member

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    I agree. A rock only 100 meters wide could cause an explosion yeilding more than a million tons of TNT.
     
  16. ElectricFetus Sanity going, going, gone Valued Senior Member

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    (whips out calculator makes estimate of equivalent density and velocity)

    That would be 33.6megatons if 1950 DA was only 100meters wide instead of 1.1km.

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    Last edited: Feb 26, 2003
  17. Jaxom Tau Zero Registered Senior Member

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    And then it will get ugly, and the finger pointing and lynching will begin. The politicians who don't run away will get hung because of their inaction. And the complimentary riots will ensue. Six months, hell, six years is not enough time to do anything about even a small city killer, even if we had easy access to space.

    Nukes are most likely the method, specially if it's a last minute shove, but the technique depends heavily on the type of structure. If it's a large iron chunk, then a close nuke in an enclosed crater would provide a good shove...a stony asteroid may allow the same thing, but it could also potentially fracture, and then the fragments may or may not be a problem. Comets are the hardest to predict...It looks as if most of these bodies are fragile, so a close nuke could just make a shower of fragments too numerous to deal with. All nukes in space would create thrust by the vaporization of a part of the body, but to do so with a comet without breaking it apart would require to practice. That and the fact that comets are much faster incoming due to their usual orbits. Little warning and hard to move...

    Either type, if we have warnings of 20 or more years, could be easily moved enough by simple engines, a few nukes, or even a solar sail. Time is the key...the more time, the less of an angle you need to change.

    For the record:

    metric ton = 1000 kg

    megaton = 10^6 x 10^3 kg = 10^9 kg

    kg TNT = 4 x 10^6 joules

    megaton TNT = (10^9 kg) 4 x 10^6 joules / kg = 4 x 10^15 joules

    10 km asteroid:

    density = mass/volume = 2.5 g/cc or 2,500 kg/m3

    V = 4/3 pi R^3 = 5.22 x 10^11 m3

    V x M / V = M = 5.22 x 10^11 m^3 x 2.5 x 10^3 kg/m^3

    Þ mass = 1.3 x 10^15 kg

    Earth: velocity = escape velocity (11 km/sec) +

    typical relative velocity (9 km/sec)

    400 x 10^6 m^2/sec^2

    Þ velocity = 20 km/sec

    km / sec = 10^3 m/sec

    E = 1/2 m v^2 = 1/2 (1.3 x 10^15 kg) (20 x 10^3 m/sec)2 = 2.6 x 10^23 joules

    2.6 x 10^23 joules / 4 x 10^15 joules/megaton = 6.5 x 10^7 megatons

    Or 1.1 million of our biggest bombs.

    And 10 km is average, but hardly a big asteroid...

    Estimates based on the Hellas impact area on Mars predict that was an object around 12 km in size.

    And lastly, a comet the same size would likely have less density, but be moving much faster...it averages out.

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    Last edited: Feb 26, 2003
  18. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Jaxom,

    Nice with the explosive force and all... I was just saying how much a 100m would be at the same density and velocity of 1995 DA.

    As for nukes on comets considering what a comets made of blowing it to snow flakes would be a good thing! Its the dust clad asteroids we need to worry about... hard to move and hard to destroy. True though anything thing under ~5 years is going to be very hard to deflect! As for your dooms day prediction: I think in 6 months time the whole world would have collapsed and gone to hell… and then the comet would hit!
     
  19. Jaxom Tau Zero Registered Senior Member

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    Well, here's the problem...we really don't know what a nuke would do to an average comet. It may act just as a solid body, it may totally vaporize it, or something inbetween (which would be the worse case scenario, but also the most likely

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    We are seriously lacking research in these things...and it could come back and bite us if we don't begin to take the threat seriously. Some days I reluctantly wish for a small impact to give us a wake up call...but the smaller ones tend to detonate in the upper atmosphere, so there's no evidence to the general public, only to setups like NORAD.
     
  20. blobrana Registered Senior Member

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    There is a relationship with the spin of an asteroid and its composition.

    1950da spins quite fast, this implies that it is composed of a rocky/metallic material.

    If it were made of loose rock/ice then nuclear explosions would be absorbed by the object and not be be diverted.

    The bad thing is that most of the asteroids are slow spinning.

    We know of most of the 10km near earth asteroids. but we probably only know about 50% of the 1 km sized ones...

    (The dinosaur killer was probably 10 km).
     
  21. ElectricFetus Sanity going, going, gone Valued Senior Member

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  22. Jaxom Tau Zero Registered Senior Member

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    Yep, that's a good mission to watch for. The mission objectives are a few of the points I've touched on. Using data from this, they could get at least an idea on what a nuke/impact effort would do.

    Then again...every body out there is different. Fetus, you mentioned going out to examine the body before determining what to do...I think that is critical to be a success. Of course, if there's no time, we have to guess, and hope for the best. :bugeye:

    Blobrana, spin is yet another issue. We'd have to determine how offset the vector would be from the explosion, or despin the body...
     
  23. blobrana Registered Senior Member

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    @Jaxom
    sry, i didn`t put it clear enough.

    We can determine the composition of an asteroid by measuring it`s spectra and spin.

    Denser asteroids have a faster spin. (generally)
     

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