Killer Asteroids

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Killer Asteroids

BBC's UKTV documentary arm's Killer Asteroids: Averting Armageddon tries to shed some light on just that - an asteroid over a kilometer wide hitting the Earth's surface and exterminating life as we currently understand it. Despite our best efforts to catalogue the skies above, only a relatively microscopic portion of them have been "checked" for this type of killer comet.

Despite our limited surveying capabilities, we have been able to detect an asteroid that is on a collision course with our planet, due to hit around 875 years from now. This discovery has led to a number of astrophysicists scrambling to find a way to avert what is widely accepted as our definitive demise, unless of course these scientists succeed.

Initial hypotheses posed a solution that is basically the story told in Michael Bay's 1999 blockbuster film Armageddon, where a nuclear warhead would either be fired at the meteor or taken up to the asteroid's surface and buried deep within its core prior to detonation, with the intent of blowing it apart before it poses a threat. Scientists almost immediately discredited the idea, as nuclear weaponry we currently have at our disposal does not even come close to the caliber necessary to accomplish this.

Nuclear warheads in use today have the capabilities in the 20 megaton range, whereas we would need around a 1000 megaton explosion to have any effect on an asteroid of this size. And even if this were possible, the dangers of creating a bomb of this magnitude and strapping it to a rocket to send up into space far outweighs that of the asteroid's impact.

A plan B was founded on the basis that a reasonably large explosion created near the asteroid, if it were long enough in advance (ten years is the figure cited in the film) of hitting its target - Earth in this case, it should divert the trajectory of the mass by a few inches. This minute change, multiplied exponentially over the course of the asteroid's travels, would be enough to send it whizzing by our planet at a safe enough distance.

This too is shown to not be a guarantee, and more theories are considered as the film runs its course. Whether any of them are enough to save us one day, only time will tell.

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4 Comments / User Reviews

  1. david the bear

    informative,interesting and nothing we can do! a good doc to watch and not ponder to much...

  2. Richard Neva

    I believe the dollar will fail long before an asteroid will hit the world.

  3. Shrike

    Believe it or not, Richard, the dollar failing is not the end of civilization - it's just business as usual for history. It won't even be the first global reserve currency to find itself knocked off its pedestal in modern times (that would be the pound stirling in 1944). Social collapse, wars, famines, economic disasters, empires failing ... these are all repeating events. Not a century has gone by without them.
    The impact of an asteroid of that size, however, is a completely different story.

  4. T. McGrath

    An asteroid that is 1 km in diameter, made of dense rock (3 g/cm^3), traveling at 20 km/s, impacting the Earth at an angle of 30° just off the coast in 1 km of water, would have the following effect if you were 1,000 km away:

    1) The projectile begins to breakup at an altitude of 56600 meters (186,000 ft). The impact energy would be 3.08 x 10^20 Joules = 73,500 MegaTons of TNT. The impact would displace the water by a diameter of 16.1 km ( 9.98 miles ). The initial crater formed in the seafloor would be a diameter of 6.68 km (4.15 miles) and 2.36 km (1.47 miles) deep. The final crater diameter would be 8.6 km (5.34 miles) and 566 meters (1,850 feet) deep. The volume of the target melted or vaporized would be 0.237 km^3 (0.0568 miles^3). Roughly half the melt remains in the crater, where its average thickness is 6.76 meters (22.2 feet).

    2) The ejecta will arrive 1,000 km away approximately 8.24 minutes after the impact. It would consist of a fine dusting of ejecta with occasional larger fragments. The average ejecta thickness would be 17.8 microns (0.7 thousandths of an inch). The mean fragment diameter would be 121 microns ( 4.76 thousandths of an inch).

    3) At 1,000 km distance the fireball would be below the horizon, therefore no direct thermal radiation. At 3.33 minutes after the impact there would be a major earthquake 7.3 magnitude at 1,000 km distance.

    4) The air blast will arrive 1,000 km away approximately 50.5 minutes after impact. The peak over-pressure would be 2,720 Pa (0.0272 bars or 0.386 psi) with a maximum wind velocity of 6.33 m/s (14.2 mph) accompanied by a loud bang at 69 dB (as heavy traffic).

    5) The impact-generated tsunami wave arrives 1,000 km from impact approximately 2.82 hours after impact. Tsunami wave amplitude is between 8.04 meters (26.4 feet) and 16.1 meters (52.7 feet).

    If such an impact occurred near (within 1,000 km) a major coastal city, it would definitely cause serious damage. Such asteroids can certainly be city-killers, but they would not effect the overwhelming majority of the planet.

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