This area will cover relevant news of the threat to the planet from Near Earth Objects (NEOs) including concepts and designs for mitigation. All opinions are those of the author.

27 March 2009

Paper: Tunguska-1908 and similar events in light of the New Explosive Cosmogony of minor bodies

Selections from an article on a new technical paper about the Tunguska event. The author makes the claim that the Tunguska event was caused by a comet that hit at a tangent to the Earth's surface, and essentially bounced off the atmosphere. Selections from the article follows...

Despite a century of study, many aspects of the Tunguska event are still unexplained. For example, the explosion released more energy than a thousand Hiroshima-type atom bombs and yet left no crater. A similar-sized object is thought to have hit North America some 12 000 years ago, triggering the megafaunal extinction and widespread cooling. And yet the Tunguska event seems to have left our climate intact.

Now a new analysis by Edward Drobyshevski of the Russian Academy of Sciences in St Petersburg Russia claims to have solved these problems. Drobyshevski concludes that the object that hit in 1908 was a comet (as have many scientists before him). But unlike the others, he has been able to calculate that this comet hit the Earth's atmosphere almost at a tangent and broke apart.

The larger part of this comet skipped off the atmosphere, back into an Earth-crossing orbit (we should expect to find it nearby, predicts Drobyshevski).The smaller part rapidly heated up above Russia before exploding in the atmosphere over Tunguska.

The key to why it left so little lasting damage is the nature of the explosion, says Drobyshevski. And the key to that is our improved understanding of the chemical make up of comets. He says the comet would have had a high hydrogen peroxide content and this would have dissociated explosively as it heated up to produce oxygen and water, breaking the comet apart. It was this explosion that devastated Tunguska.

"Significantly, the energy of the chemical explosion is substantially lower than the kinetic energy of the body," says Drobyshevski.

This explains the comet's relatively benign affect on the planet and solves many of mysteries associated with the event, he says.

Link: Technology Review Article

Link: Paper Abstract

Link: Paper (PDF)

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