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Planetary Defense: Protecting Earth from Asteroids

Posted by michael on from the insert-one-credit-to-continue dept.

securitas writes "Space.com has published a feature about developing a planetary defense against catastrophic comet and asteroid impacts. The story arises from the aptly named 'Planetary Defense Conference: Protecting Earth from Asteroids' held in California February 23-26. The article discusses potential methods to prevent an impact, the need for study missions to comets and asteroids, the to-date haphazard approach to monitoring Near Earth Objects (NEOs), and the NASA/US Air Force Spaceguard Survey, which aims to discover and track 90% of 'Near Earth Asteroids (NEAs) with a diameter greater than 0.6 miles (1-kilometer) by 2008.' Some ideas for anti-impact technologies to develop include gas blasts, nuclear detonations, ramming microsatellites, lasers, mass drivers and gravitational tractor beams. The most disturbing message from the conference? 'It may take a celestial body hit to Earth' before governments take any meaningful steps to address this danger. Mirror at USA Today."

3 of 342 comments (clear)

  1. A few related sites..... by Scrab · · Score: 5, Informative

    http://more.abcnews.go.com/sections/science/DailyN ews/asteroid0107.html

    http://personals.galaxyinternet.net/tunga/I7.htm

    http://home.att.net/~thehessians/asteroidstrike. ht ml

    http://www.sandia.gov/media/comethit.htm

    http://www1.tpgi.com.au/users/tps-seti/crater.ht ml

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  2. Umm... by Jexx+Dragon · · Score: 4, Informative
    The most disturbing message from the conference? 'It may take a celestial body hit to Earth' before governments take any meaningful steps to address this danger.

    Everyday something hits earth, comets, mini asteroids, space dust. Most burns up in the atmosphere, but every so often something makes it through (meteorites) and hits the surface. True most of these meteorites are about the size of a golf ball or smaller.

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  3. No, YOU don't understand stats by NoData · · Score: 5, Informative

    To say that probability of something uncertain happening is "50% No more, no less" is a classic trap in misunderstanding the meaning of probability. Because an event has two possible states (does occur, does not occur) does NOT mean the probability of it occurring is 50%...This is degenerate and wrong thinking in probability. The best estimate of the probability of something happening is exactly equal to the rate at which that event occurred previously. This is called the base rate or prior probability and is integral to Bayes' theorem (please see this). Thus, if you flip a coin (of unknown fairness) 100 times and 41 of those flip come up heads, what's the best estimate of the probability that the next flip will be heads? 41%. [Side note: There are tests to determine if this rules out the coin being fair or not, but even these assume some a priori criterion for ruling out chance effects (i.e., "I'll call it unfair if the coin's pattern is likely to happen by chance less than 5% of the time"...this is called the "alpha level" of such tests).]

    Anyway, there is a special distrubtion to describe the occurrence of random events in time (the Poisson distribution), but suffice it to say, the probability of an asteroid hitting the earth in the next decade is NOT 50%. This would only be true if, in the past, an asteroid has hit the earth (on average) once every other decade.