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RE: [DOEWatch] Understanding the tsunami threat to coastal nuclea r power plants
Neil, David wrote :
Well, if you go somewhere outside the Oort Cloud, the probability of an
encounter drops to effectively zero in a human lifetime. };-D
Not that it's realistically greater than zero for any given spot on Terra
for the same timespan.
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....but recall that Barbara Hamrick's question was :
>
> What I want to know is, how do I get to the nearest asteroid-free zone?
>
....note the "how" !
....may I suggest nuclear propulsion as the most rapid means, providing the
shortest exposure to cosmic radiation en route ?
...and since the Oort Cloud surrounds the Solar System fairly uniformly, may
I suggest a route that takes you past that potulated earth-threatening
asteroid and blow it off course with one or more nuclear bombs ?
OK, enough of this silliness already...
Jaro
PS. As I recall, there are perhaps two or three documented accounts, in
recent decades, of small (ie. a couple of inches) meteorites actually
hitting man-made objects like houses and cars. Clearly a very rare event,
with the probability of hitting a specific target like a nuclear plant being
extremely remote, even for such small rocks (which might, at most, perhaps
damage a tranformer outside the containment dome...).
For large(r) rocks that could do real damage the probabilities are
infinitely smaller.
One reason is that even fairly large meteors entering the earth's atmosphere
typically disintegrate before ever reaching the ground, and any little
fragments that make it to the surface have relatively low terminal speed
(the damage to the car & houses cited above was minimal...).
For example :
http://www.hamiltonspectator.com/news/402801.html
Heavens On Earth In Hagersville
Kate Barlow
The Hamilton Spectator (Canada)
April 26, 2001
Scientists are working to unlock the secrets of a billions-of-years-old
chunk of space metal found in a Hagersville farmer's field. Almost certainly
a meteorite, the 30-kilogram chunk of iron, nickel and other minerals is
most likely to have started life as the core of a small doomed planet formed
early in the history of our solar system.
Richard Herd, curator of the National Meteoric Collection of Canada at
Natural Resources Canada, says only 58 meteorites have been identified in
Canada since 1842. Most of the 10,000 tonnes of debris regularly floating in
space either burns up during its fiery passage through the atmosphere or
falls into the Earth's oceans to lie forever undisturbed.
http://www.skypub.com/news/news.shtml
Thursday, January 20 2000
Meteoric Blast over Canada
A chunk of interplanetary debris slammed into Earth's atmosphere over
western Canada on January 18th, exploding with what impact specialist Alan
Hildebrand (University of Calgary) calls "one of the largest ever airbursts
detected over land." The daylight event occurred at 16:43:26 Universal Time
(8:43 a.m. Pacific Standard Time) at 60.25° north, 134.65° west - a little
south of Whitehorse, Yukon Territory. Sensors aboard defense satellites
suggest that the airburst unleashed energy equivalent to at least
2,000-3,000 tons of TNT about 25 kilometers above the ground. Residents of
Whitehorse observed a lingering dust cloud for 2 hours. According to
Hildebrand, the impactor was most likely a stony object. He asks
eyewitnesses of the event to contact him at 403-220-2291
(hildebra@geo.ucalgary.edu).
Later that day, amateur astronomers in the surrounding region noticed an
unusual display of noctilucent clouds hanging low in the western sky after
sunset. A "webwork of interwoven strands" formed a cloud band was about 15°
across, notes Michael Hoskinson of Edmonton, Alberta, creating "a silvery
radiance that far outshone the dying sky light." The meteoric dust particles
left in the stratsophere apparently served as condensation nuclei for the
dramatic cloud formation. "Noctilucent clouds normally occur in June or July
only," explains meteorologist Alan Whitman, who observed the band while
driving to his home in Penticton, British Columbia.
SKY & TELESCOPE'S NEWS BULLETIN - MARCH 16, 2001
http://www.skypub.com
TAGISH LAKE: MYSTERY METEORITE
At last year's Lunar and Planetary Science Conference, held each March
in Houston, Texas, meteorite specialists were salivating over the
Tagish Lake meteorite, which had dropped as a hail of fragments onto
the Yukon's winter wilderness just two months before. Within days of
the fall, local outdoorsman Jim Brook carefully collected nearly a
kilogram of icy fragments and stashed them in his freezer. Later a
team of Canadian geologists and volunteers scoured the lake's frozen
surface to collect as much of the fragile interplanetary material as
possible before the spring thaw swallowed up the remaining pieces.
Remarkable as much for the rapid, textbook recovery effort as for the
stones' black, carbon-rich texture, Tagish Lake was hailed as the most
important find in some 30 years.
<SNIP>
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J.
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