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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
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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To: Fred Nerks

[sigh] 30 or so years ago I read “The Fire Came By”, which tries to make a case for the nuclear explosion of an extraterrestrial craft which was having engine trouble. The aliens changed direction so that, in case they didn’t quite make it in time, the explosion would happen in an area with very low population density. I guess they missed the Sahara...


21 posted on 12/18/2007 8:30:47 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: Fred Nerks

My hovercraft is full of eels.


22 posted on 12/18/2007 8:30:54 PM PST by blam (Secure the border and enforce the law)
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To: blam

so, watcha gunna do about it, hmmm?


23 posted on 12/18/2007 8:53:10 PM PST by Fred Nerks (FAIR DINKUM!)
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To: SunkenCiv

..ok, but what about my poor twisted trees?


24 posted on 12/18/2007 8:58:20 PM PST by Fred Nerks (FAIR DINKUM!)
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To: Fred Nerks
"so, watcha gunna do about it, hmmm?"

S Roždestvom Khristovym i S nastupayuščim Novym Godom.

25 posted on 12/18/2007 9:02:02 PM PST by blam (Secure the border and enforce the law)
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To: crazyshrink

bump


26 posted on 12/18/2007 9:05:27 PM PST by VOA
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To: Fred Nerks

Oakstioarthritis, a doctor viewed the pics and is a grain with me.


27 posted on 12/18/2007 9:10:36 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: blam

..and a very Merry Christmas and a Happy New Year to you too!


28 posted on 12/18/2007 9:21:48 PM PST by Fred Nerks (FAIR DINKUM!)
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To: Fred Nerks

AYE!


29 posted on 12/18/2007 9:26:19 PM PST by blam (Secure the border and enforce the law)
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To: okie01

Apparently.


30 posted on 12/18/2007 11:23:30 PM PST by BenLurkin
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To: SunkenCiv; All

According to a book which includes the Tungusku incident, people in London could read a newspaper at night from the glow. Also there was a similar event in the Amazon forest in the mid 20th century that had a 50 mile diameter blowdown area. Wish I could find the book I read these things in, will continue to look.


31 posted on 12/19/2007 9:40:58 AM PST by gleeaikin
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To: gleeaikin
Here's an omnibus of links to just a few of William Corliss' Science Frontiers briefs about impacts:
A Bright Flying Object And Another Enigmatic Crater
"On the early morning of 1994 January 18, a very bright luminous object crossed the sky of Santiago de Compostela, Spain... A surface "crater" in Cando (close to Santiago) with dimensions 29 x 13 m and 1.5 m deep was later discovered within 1 km of the projected "impact" point of the luminous object.
Exotic Seismic Signals
"On the afternoon of December 9, 1995, a bolide exploded in the atmosphere over the Andes in southern Ecuador. Many people in nearby towns witnessed the event. They reported seeing a streaking meteor, which terminated in a loud and brilliant explosion. In some locales, the flash was noticeable even through cloud cover. The burst of light was observed by satellite optical sensors used to detect atmospheric nuclear tests. Three local seismic stations also recorded signals from the explosion...This bolide appears to be unique in that it was observed by eyewitnesses and located by both satellite and ground-based sensors."
A Meteor Impact Or Earth Slump?
About 10:10 PM [November 22, 1996], the residents of this area [the Honduras-Guatemala border] observed a red-and yellow fireball moving east-to-west. The bolide's passing was marked by a loud detonation. From this information, one would bet heavily that this was simply a routine meteor detonation caused by the heat generated during entry into the atmosphere... So far, investigators have not been able to decide whether the landslide is just gravity-slumping on the slope or a disturbance created by the night's meteor.
Target: South America
"They landed in the centre of the forest with a triple shock similar to the rumble of thunder and the splash of lightning. There were three distinct explosions, each stronger than the other, causing earth tremors like those of an earthquake. A very light rain of ash continued to fall for a few hours and the sun remained veiled till midday. The explosions of the bodies were heard hundreds of kilometres away."... Only five years after the Brazilian event, a large bolide apparently smashed into the jungle of Guyana. Buried in the library stacks, we found a mostly forgotten trio of reports on the 1935 event in a 1939 issue of The Sky, predecessor of Sky & Telescope. The articles suggest that the devastated area "may equal or exceed that of the great Siberian meteor of 1908." ..."Scientists in Brazil's northeastern state of Piaui are baffled by a crater that was punched into the tropical rain forest shortly after witnesses reported seeing a bright light streak across the sky. Researchers are uncertain whether the crater, 16 feet wide and 32 feet deep, was left by a meteorite or a piece of a comet. Physicist Paulo Frota of the University of Piaui believes it was caused by a block of ice from a comet because the surrounding vegetation is not burned and the crater's rim is not raised."
Giant Impact-wave Deposit Along U.S. East Coast
[D]eep-sea drillers have charted the Exmore Boulder Bed... over 60 meters thick in places and [covering] more than 15,000 square kilometers... argon dating of the ejecta yield a date of 35.5 million years, which correlates with the North American tektite strewn field... Our planet's land surfaces are also strewn with many debris deposits that are probably the consequence of giant impact waves.
Everglades Astrobleme?
At a recent meeting of the Geological Society of America, E.J. Petuch proposed that the Everglades region received a direct hit from an asteroid about 36 million years ago. The Everglades region is a swampy, forested area surrounded by an oval-shaped system of ridges. Geologists usually maintain that the Everglades represent a collapse feature caused by groundwater dissolving away limestone... Petuch disagrees with the collapse theory. [diagram shown on page]
Eight Little Craters All In A Row
M.R. Rampino and T. Volk describe a possible swath of meteoric devastation across the North American Midwest. The craters are all roughly the same age: 310-330 million years. Rampino and Volk suspect they were formed all at once by a string of asteroids or comets.
also this one, and I'm glad to find it, I'd remembered it but hadn't been able to find it on the drive or online.
Possible Formation of the Guatemala Basin by the Impact of an Extraterrestrial Body
by Charles E. Corry and Miller L. Bell
The earth must be as frequently cratered per unit area as the moon. By a relative cross section argument, more than 13 times the number of craters the size of the maria on the moon exist, or existed, on the earth. Whether such events occur with sufficient frequency in recent geologic time to provide tangible evidence today of such cratering is uncertain. From the arguments set forth, and the continuing discovery of meteorite craters on the continents (Short, 1966, Baldwin, 1963, Dietz, 1961, and Prouty, 1952) it seems likely that the importance of the effect of extraterrestrial bodies impacting the earth has been, at least, underestimated (the Alverez's hypothesis concerning the end of the dinosaurs by such a mechanism was more than a decade in the future). Certainly there is as much evidence at present to support our hypothesis for the formation of the Guatemala Basin as other hypotheses advanced to explain the low heat flow found in this basin.

With the tests for shock processes advanced by Short (1966), our hypothesis should be capable of field verification or rejection.

[1999 -- The letter of rejection from Nature for the following article is dated August 28, 1968. At the time most earth scientists would not even accept the fact that meteorites regularly impacted the earth. For example, Barringer Crater in Arizona was still thought by many to be of volcanic origin, as well as the craters on the moon. Bob Dietz had just published his work on shatter cones but I wouldn't say that had been generally accepted. There was not even general agreement on sea floor spreading and plate tectonics outside the radical few at Scripps, Woods Hole, and related institutions.]

32 posted on 12/19/2007 11:27:05 AM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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Scientists say asteroid may hit Mars in late January
(1 in 75 chance on Jan. 30, 2008)
AP on Examiner.com | 12/20/07 | Alicia Chang - AP
Posted on 12/20/2007 9:27:00 PM EST by NormsRevenge
http://www.freerepublic.com/focus/news/1942591/posts


33 posted on 12/21/2007 9:54:55 PM PST by SunkenCiv (Profile updated Tuesday, December 18, 2007___________________https://secure.freerepublic.com/donate/)
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To: crazyshrink

Is that an inkblot?


34 posted on 12/21/2007 10:05:01 PM PST by ValerieTexas
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To: SunkenCiv

You can bet that lots of telescopes will be watching for that possibility.


35 posted on 12/22/2007 9:16:23 AM PST by reg45
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SIBERIA METEORITE FLATTENS 40 SQ MILES
The Times | 7 June 2003 | Robin Shepherd
Posted on 06/09/2003 5:25:21 PM PDT by Mike Darancette
http://www.freerepublic.com/focus/news/926025/posts


36 posted on 04/13/2008 12:52:42 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/_____________________Profile updated Saturday, March 29, 2008)
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