Research sheds new light on asteroid disaster

[Bolt_Gundam510]

ALBUQUERQUE, New Mexico (AP) -- An asteroid that exploded over Siberia a century ago, leaving 800 square miles of scorched or blown down trees, wasn't nearly as large as previously thought, a researcher concludes, suggesting a greater danger for Earth.

According to supercomputer simulations by Sandia National Laboratories physicist Mark Boslough, the asteroid that destroyed the forest at Tunguska in Siberia in June 1908 had a blast force equivalent to one-quarter to one-third of the 10- to 20-megaton range scientists previously estimated.

Better understanding of what happened at Tunguska will allow for better estimates of risk that would allow policymakers to decide whether to try to deflect an asteroid or evacuate people in its path, he said.

"It's not clear whether a 10-megaton asteroid is more damaging than a Hurricane Katrina," Boslough said. "We can more accurately predict the location of an impact and its time better than we can a hurricane, so you really could get people out of there if it's below a certain threshold."

On Tuesday, an asteroid at least 800 feet long was making a rare close pass by Earth, but scientists said there was no chance of an impact. The closest approach of 2007 TU24 will be 334,000 miles -- about 1.4 times the distance of Earth to the moon. An actual collision of a similar-sized object with Earth occurs on average every 37,000 years.

Although the computer simulation shows the Tunguska asteroid was smaller, its physical size isn't known. That would depend on such factors as speed, shape, how dense or porous it was and what it was made of, Boslough said.

Smaller asteroids approach Earth about three times more frequently than large ones. So if large asteroids approach about every 1,000 years, a smaller one would be about every 300 years, Boslough said.

"Of course there's huge uncertainties," he said.

The three-dimensional computer simulations were done last summer. Boslough presented the findings at scientific meetings in September and December. A paper on the phenomenon, co-authored by Sandia researcher Dave Crawford, has been accepted for publication in the International Journal of Impact Engineering.

The simulation, which better matches what's known of Tunguska than earlier models did, shows that the center of the asteroid's mass exploded above the ground, taking the form of a fireball blasting downward faster than the speed of sound.

But the fireball did not reach the ground, so while miles of trees outside the epicenter were flattened, those at the epicenter remained standing -- scorched, with their branches stripped off.

Boslough said they were likened to telegraph poles by the first Russian expedition to Tunguska -- an expedition that didn't arrive until 1927 because of the distance, primitive travel conditions and turbulent times in Russia.

If the asteroid had been as large as previously thought, "it would have had really different effects on the ground," Boslough said.

"It wouldn't have just blown over trees. There would have been a zone of completely scorched earth for several miles," he said. "That fireball would have come all the way down to the surface and everything it came in contact with would have basically just vaporized."

Alan Harris, a planetary scientist at Space Science Institute in Boulder, Colorado, said he's been following Boslough's work on Tunguska for several years "and I think the idea that he has there seemed very sound."

"A meteorite or asteroid coming into Earth's atmosphere has a lot of momentum," he said. "The idea that it would push down into the atmosphere seems very plausible."

"The bottom line is it takes a lot less energy, a small explosion, to create ground damage" such as that at Tunguska, said Harris, who studies the frequency of such impacts to assess hazards.

In the future, he said, he'll take Boslough's work into account and revise estimates of damage from impacts by smaller objects.

Source: CNN TECHNOLOGY

[myidisbb]

i seem to remember it was a comet that exploside just above the surface. i know they figure the speed and angle long time ago. the fallen trees had a butterfly look to them. in a lab they was able to show. the angel and speed to make it. watch it on tv once.

anyway, Hurricane Katrina was a CAT 3 when it hit land. it was nothing special storm. the problem was media hype, democrats in control of NO & LA and lazy, welfare NO people and worst of all, pure evil, hate of president bush. it is illegal for the federal government to go help any state. they try to get around it by having the state govenor ask for fema help. it is still illegal and unconsultation. history has shown that private level does a better job in disasters

Mississippi got the direct hit. the NorthEast position of winds going counterclockwise is the bad area.

[dock98]

i remember seeing this on the history channel.pretty interesting.

[LoKz]

i saw a report on that it was a UFO i think...

[mjall]

it's scary to know that one of those asteroids gonna hit us ..................

[LoKz]

it's scary to know that one of those asteroids gonna hit us ..................

Might and lets not think like that :(

[dock98]

it's scary to know that one of those asteroids gonna hit us ..................

Might and lets not think like that :(

your right on l,no point in worrying about what we cannot control.

[LoKz]

think good :( and hopefully somebody build a missile or a gravity thing to move it out of orbit... :dance2: and dock98 is right we have no control on it...

[irefay]

Actually, there is something we can do about it. If we were to build some "land bridges" to connect the continents and then have everyone look at the asteroid as it approached we may be able to bounce enough photons off of the asteroid to change its course. Meh, just thought I would throw that out there. <_<

[Chicano666]

Why worry so much, or at all? We are set to die right from the day we are born. Each day that passes its us getting closer to our death, unless the natural course is interrupted by an accident/suicide/murder. Lets not worry about something that, wheather or not it occurs, we are unable to do something about it. Also, if a missile system or whatever is built, who is going to be in charge? Imagine the capabilities such an apparatus will have for warfare. Do we really want to build something that can do such a thing? If you ever played Ace Combat 4 you know what I mean <_<

[dock98]

Actually, there is something we can do about it. If we were to build some "land bridges" to connect the continents and then have everyone look at the asteroid as it approached we may be able to bounce enough photons off of the asteroid to change its course. Meh, just thought I would throw that out there. :)

huh?