Thursday, January 11, 2007

We’re All Going to DIE!...Well, Eventually, Anyway.

As David Noland of Popular Mechanics notes, “More than 100,000 asteroids hurtle past our planet. But only one--that we know of - may hit us in the next 30 years.”

That ONE is a 25-million-ton, 820-ft.-wide asteroid called 99942 Apophis and scientists are 99.7% certain that it’s due to miss the earth by about 20,000 miles, a negligible distance in astronomical terms, in the year 2029.

What’s more, if it passes at precisely 18,893 miles, “it will go through a "gravitational keyhole." This small region in space - only about a half mile wide, or twice the diameter of the asteroid itself - is where Earth's gravity would perturb Apophis in just the wrong way, causing it to enter an orbit seven-sixths as long as Earth's. In other words, the planet will be squarely in the crosshairs for a potentially catastrophic asteroid impact precisely seven years later, on April 13, 2036.”

Worse yet, if Apophis is headed for that gravitational keyhole, earth's ground observations won't be able to confirm it until at least 2021 and by that time, it may very well be too late to do much about it."

NASA estimates that to nudge Apophis outside the orbit of the keyhole would merely require changing Apophis's velocity by a mere 0.0001 mph - about 31 in. per day - in three years its orbit would be deflected by more than a mile, a piddling amount, but enough to miss the keyhole. That's easily within the capabilities of a gravity tractor or kinetic energy impactor. A transponder-equipped gravity tractor could be launched for $250 million.

A bargain considering the estimated $400 BILLION in infrastructure damage a collision with Apophis would create.

Still, to date NASA hasn’t been in the mitigation business and no parameters have been established for NASA’s involvement in such matters. As James Noland notes, “When do we start? Or, alternatively, at what point do we just cross our fingers and hope it misses? When the odds are 10-to-1 against it? A thousand-to-1? A million?”


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