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Sandia supercomputers offer new explanation of Tunguska disaster
EurekAlert ^ | 12/18/07 | Mark Boslough

Posted on 12/18/2007 10:12:19 AM PST by crazyshrink

Smaller asteroids may pose greater danger than previously believed

INCINERATION POSSIBLE - Fine points of the "fireball" that might be expected from an asteroid exploding in Earth's atmosphere are indicated in a supercomputer simulation devised by a team led by Sandia researcher Mark Boslough. (Photo by Randy Montoya ) Download 300dpi JPEG image (Media are welcome to download/publish this image with related news stories.)ALBUQUERQUE, N.M. — The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.

“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”

Because smaller asteroids approach Earth statistically more frequently than larger ones, he says, “We should be making more efforts at detecting the smaller ones than we have till now.”

The new simulation — which more closely matches the widely known facts of destruction than earlier models — shows that the center of mass of an asteroid exploding above the ground is transported downward at speeds faster than sound. It takes the form of a high-temperature jet of expanding gas called a fireball.

This causes stronger blast waves and thermal radiation pulses at the surface than would be predicted by an explosion limited to the height at which the blast was initiated.

“Our understanding was oversimplified,” says Boslough, “We no longer have to make the same simplifying assumptions, because present-day supercomputers allow us to do things with high resolution in 3-D. Everything gets clearer as you look at things with more refined tools.”

Sandia is a National Nuclear Security Administration laboratory.

The new interpretation also accounts for the fact that winds were amplified above ridgelines where trees tended to be blown down, and that the forest at the time of the explosion, according to foresters, was not healthy. Thus previous scientific estimates had overstated the devastation caused by the asteroid, since topographic and ecologic factors contributing to the result had not been taken into account.

“There’s actually less devastation than previously thought,” says Boslough, “but it was caused by a far smaller asteroid. Unfortunately, it’s not a complete wash in terms of the potential hazard, because there are more smaller asteroids than larger ones.”

Boslough and colleagues achieved fame more than a decade ago by accurately predicting that that the fireball caused by the intersection of the comet Shoemaker-Levy 9 with Jupiter would be observable from Earth.

Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth’s atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.

Because of the additional energy transported toward the surface by the fireball, what scientists had thought to be an explosion between 10 and 20 megatons was more likely only three to five megatons. The physical size of the asteroid, says Boslough, depends upon its speed and whether it is porous or nonporous, icy or waterless, and other material characteristics.

“Any strategy for defense or deflection should take into consideration this revised understanding of the mechanism of explosion,” says Boslough.

One of most prominent papers in estimating frequency of impact was published five years ago in Nature by Sandia researcher Dick Spalding and his colleagues, from satellite data on explosions in atmosphere. “They can count those events and estimate frequencies of arrival through probabilistic arguments,” says Boslough.

The work was presented at the American Geophysical Union meeting in San Francisco on Dec. 11. A paper on the phenomenon, co-authored by Sandia researcher Dave Crawford and entitled “Low–altitude airbursts and the impact threat” has been accepted for publication in the International Journal of Impact Engineering.

The research was paid for by Sandia’s Laboratory-Directed Research and Development office.

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Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin company, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.


TOPICS: Astronomy; Science
KEYWORDS: asteroid; asteroids; catastrophism; deepimpact; russia; siberia; tunguska; weredoomed
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INCINERATION POSSIBLE - Fine points of the "fireball" that might be expected from an asteroid exploding in Earth's atmosphere are indicated in a supercomputer simulation devised by a team led by Sandia researcher Mark Boslough. (Photo by Randy Montoya )
1 posted on 12/18/2007 10:12:20 AM PST by crazyshrink
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To: crazyshrink
“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough...

Whereupon, he offers us 750 words -- without a single clue as to the asteroid's size, before or after the simulation.

2 posted on 12/18/2007 10:21:50 AM PST by okie01 (THE MAINSTREAM MEDIA: Ignorance on Parade)
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To: crazyshrink
--The new interpretation also accounts for the fact that winds were amplified above ridgelines where trees tended to be blown down, and that the forest at the time of the explosion, according to foresters, was not healthy. Thus previous scientific estimates had overstated the devastation caused by the asteroid, since topographic and ecologic factors contributing to the result had not been taken into account.--

--I suspect "garbage in, garbage out," still applies--

3 posted on 12/18/2007 10:23:39 AM PST by rellimpank (--don't believe anything the MSM tells you about firearms or explosives--NRA Benefactor)
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To: crazyshrink


"You have been a participant in the biggest interdimensional cross rip since the Tunguska blast of 1909!"
4 posted on 12/18/2007 10:29:29 AM PST by ButThreeLeftsDo (Merry Christmas!)
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To: crazyshrink
Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth’s atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.


5 posted on 12/18/2007 10:38:01 AM PST by frithguild (Then we could even disgorge the Fed of its powers and establish a free-market monetary system.)
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To: ButThreeLeftsDo

Great movie reference!


6 posted on 12/18/2007 10:51:22 AM PST by SIDENET (Hubba Hubba...)
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To: frithguild
"explode as an airburst that precipitates the downward flow of heated gas."

Shaped Charge. Sort of a RPG from space.

7 posted on 12/18/2007 10:54:35 AM PST by Deaf Smith
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To: blam; Renfield; 75thOVI; AFPhys; Alice in Wonderland; AndrewC; aristotleman; Avoiding_Sulla; ...
Crack open a bottle of Bomb Perignon, because...
Smaller asteroids may pose greater danger than previously believed
That gets the Well-Duh award nomination for the week.
 
Catastrophism
· join · view topics · view or post blog · bookmark · post new topic ·

8 posted on 12/18/2007 6:38:29 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: okie01

“smaller”


9 posted on 12/18/2007 6:41:13 PM PST by BenLurkin
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One of the mags (could have been S&T, or Astronomy, or Science, or Nature, etc) had an article "The Big Fizzle Is Coming" -- basically an op-ed. Jupiter will just gulp it down, and there won't be so much as a disturbance of its cloud tops. Instead, each of the impactors left visible impact craters which remained for months, despite what is widely thought to be Jupiter's gaseous composition.
The Horrendous Space Kablooey at Jupiter
(the fate of comet Shoemaker Levy 9)

by Paul Schenk and Julie Moses
Shoemaker-Levy 9, LPIB, August 1994, Number 72
When astronomers on seven continents aimed every available telescope and instrument at Jupiter during the week of July 16, there were many predictions, ranging from "The Big Fizzle" to major impacts, to the disruptions of personal horoscopes and other catastrophes (Ice Ages) here on Earth. Although the magnitude of the damage done to Jupiter came as a pleasant surprise, equally surprising to scientists was that the event had actually produced visible results.

10 posted on 12/18/2007 6:44:52 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: BenLurkin
“smaller”

Than a bread box...???

11 posted on 12/18/2007 6:47:44 PM PST by okie01 (THE MAINSTREAM MEDIA: Ignorance on Parade)
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To: SunkenCiv

Perhaps the tunguska trees and the bristlecone pines shared a similar fate:

http://olkhov.narod.ru/tungus9.jpg

http://i7.photobucket.com/albums/y258/FredNerks/bristleconepine.jpg

http://olkhov.narod.ru/conf98.htm

INTERNATIONAL CONFERENCE
“90-TH ANNIVERSARY OF THE TUNGUSKA PROBLEM”
Krasnoyarsk (Russia), June 30 - July 2, 1998


12 posted on 12/18/2007 7:30:38 PM PST by Fred Nerks (FAIR DINKUM!)
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To: SunkenCiv

if you don’t speak Russian, try this:

http://i7.photobucket.com/albums/y258/FredNerks/tunguskatrees.jpg


13 posted on 12/18/2007 7:35:32 PM PST by Fred Nerks (FAIR DINKUM!)
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To: Fred Nerks

Das vadanya. Nyet. Vodka. That’s my entire Russian vocabulary. ;’)


14 posted on 12/18/2007 7:38:42 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: Fred Nerks

I was a bit surprised (http://olkhov.narod.ru/conf98.htm) to read that there *is* a tectonic “explanation” for it, iow, someone has claimed that an earthquake caused the trees to fall down for miles in all direction, just in a nice round-ish crater-like arrangement, and did nothing else for many more miles in any direction. I would also wonder how the visual sighting of the incoming object (reported in contemporary newspapers in India) could be explained by tectonics. ;’)


15 posted on 12/18/2007 7:43:19 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: SunkenCiv

You’re in luck..the reports from the INTERNATIONAL CONFERENCE are in english. (And cover just about everything, including methane...)


16 posted on 12/18/2007 7:45:38 PM PST by Fred Nerks (FAIR DINKUM!)
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To: SunkenCiv
..there are some little gems to be found in the reports:

In this case the high initial potentiality could be explained not only by mechanical or electromagnetic processes, but also by a shift that occurred in the informational sphere of the planet. This shift could result both from natural and man- generated processes, caused by upsetting the informational and energy balance. Thus, the Tunguska Event could be identified with a global manifestation of the poltergeist phenomenon in the terrestrial space...

DON'T TELL ALGORE!

17 posted on 12/18/2007 7:55:30 PM PST by Fred Nerks (FAIR DINKUM!)
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To: SunkenCiv
Nostrovia
18 posted on 12/18/2007 8:08:07 PM PST by blam (Secure the border and enforce the law)
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To: blam

Moio sudno na vozdušnoy poduške polno ugrey!


19 posted on 12/18/2007 8:18:38 PM PST by Fred Nerks (FAIR DINKUM!)
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To: blam

If that’s the plural of ‘nostril’...


20 posted on 12/18/2007 8:27:24 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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