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[10ebbor10]

I'm hearing some people say that the blast wasn't from its disintegration, just passing through the atmosphere at such high speeds. Not sure which is the true case though

Nah, impacts this size happen more or less once a year.

[olemars]

Do we have any specifics on this meteor? Size and composition?
Why did this one exert the energy of a nuclear device while others just burn up harmlessly?

Size: 10 meters
Weight: approximately 10 ton
Speed: 54000 kmh = 15 km/s

The reason it was so energetic is that for reasons mostly unknown, it explosively disintegrated during reentry (rather than burning up slowly). Hence the supersonic airblast, which did most of the damage. Similair things happened with the Tunguska event.

A 10 meter meteor would have a mass far greater than 10 tons.

The current estimate from NASA is an object of 17m diameter and mass of 10000 tons.
http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html

Spoiler: NASA brief (click to show/hide)

Update: February 15, 2013 7pm PST
New information provided by a worldwide network of sensors has allowed scientists to refine their estimates for the size of the object that entered that atmosphere and disintegrated in the skies over Chelyabinsk, Russia, at 7:20:26 p.m. PST, or 10:20:26 p.m. EST on Feb. 14 (3:20:26 UTC on Feb. 15).

The estimated size of the object, prior to entering Earth's atmosphere, has been revised upward from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass has increased from 7,000 to 10,000 tons. Also, the estimate for energy released during the event has increased by 30 kilotons to nearly 500 kilotons of energy released. These new estimates were generated using new data that had been collected by five additional infrasound stations located around the world – the first recording of the event being in Alaska, over 6,500 kilometers away from Chelyabinsk. The infrasound data indicates that the event, from atmospheric entry to the meteor's airborne disintegration took 32.5 seconds. The calculations using the infrasound data were performed by Peter Brown at the University of Western Ontario, Canada.

"We would expect an event of this magnitude to occur once every 100 years on average," said Paul Chodas of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones."

The trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, which hours later made its flyby of Earth, making it a completely unrelated object. The Russia meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia.

The reason it didn't make a bigger mess was that it hit at a shallow angle, giving it a relatively long flight time through the atmosphere in which to disintegrate and burn up.

[10ebbor10]

Yeah, that makes more sense. Otherwise it would have a density comparable to styrofoam.

Oh, and just as a note, it's unlikely that the meteorite would have impacted even on a much steeper angle. Though, depending on the density the airblast would have been much stronger, and it might have created a crater strewn field.

((Oh, and as a note. Frequency of these impacts is about every 50-100 years))

[rhesusmacabre]

That's getting on for scary big.

Apparently ESA are potentially developing a space probe to test the effects of crashing a projectile into a asteroid. The best thing, however, is the name.

[olemars]

With the current estimates the density is around 3.8 g/cm3, which could indicate a rock/iron (or rock/transformer) blend . The difference with a steeper angle would be an airburst closer to ground. If the airburst had happened at 10-15 km rather than 30-50 we wouldn't be talking about injuries from broken glass.

Here's a Russian blog I found that is compiling pictures and videos of the Meteor.

http://zyalt.livejournal.com/722930.html

Pretty spectacular stuff.

Some of those videos are amazing, especially the two where the shockwave hits.

[Grax]

The greatest thing i've ever seen.
One degree straighter the trajectory and there'd be nice crater.
I think we'll celebrate second birthday on 15th of february since now.

[10ebbor10]

The greatest thing i've ever seen.
One degree straighter the trajectory and there'd be nice crater.
I think we'll celebrate second birthday on 15th of february since now.

Nah, Even at a perpendicular angle there wouldn't have been a crater. (Maybe a small field of impacts, but no more).

At that angle, the airblast would have been strong enough to topple multistory buildings though.

[10ebbor10]

If it was enough to topple buildings, I have a suspicion that there's t least be a minor crater. Namely, due to the shockwave moving some dirt.

There wouldn't be a single crater. Or maybe there could be no crater at all. Look at the Tunguska event, for example. Entire forests unrooted, yet there was no creater, nor anything to be seen at the site.

Oh, and the shockwave is just a blast of wind, it'll blow over the ground.

[Grax]

The difference with a steeper angle would be an airburst closer to ground.

Or simply impact.

If the airburst had happened at 10-15 km rather than 30-50 we wouldn't be talking about injuries from broken glass.

Though even those glass chips were the cause of more than thousand registered accidents with heavy wounds and, i think, somewhat about 20 thousands with light injuries in total.

[10ebbor10]

The difference with a steeper angle would be an airburst closer to ground.

Or simply impact.

The asteroid didn't have the size nor structural integrity nor speed to survive the reentry.

Impact simulator

If the airburst had happened at 10-15 km rather than 30-50 we wouldn't be talking about injuries from broken glass.

Though even those glass chips were the cause of more than thousand registered accidents with heavy wounds and, i think, somewhat about 20 thousands with light injuries in total.

Just as a note, there were 1400 with wounds, of which only 20 had been heavily injured.

That's what I heard.

Oh, and another note, the entire time from reentry to desintegration was 30 seconds. It's rather hard to intercept that in time.

[Grax]

Nah, Even at a perpendicular angle there wouldn't have been a crater. (Maybe a small field of impacts, but no more).

Yesterday its path was about 700km in atmosphere, and then it burned out.

With a perpendicular trajectory its path through dense air would be a lot shorter (70-100kms), and it would save a lot of its initial mass - to strike the ground.

[Il Palazzo]

Nah, Even at a perpendicular angle there wouldn't have been a crater. (Maybe a small field of impacts, but no more).

Yesterday its path was about 700km in atmosphere, and then it burned out.

With a perpendicular trajectory its path through dense air would be a lot shorter (70-100kms), and it would save a lot of its initial mass - to strike the ground.

Try playing with that calculator Ebbor linked to. Everyday intuition doesn't net good results in extraordinary cases.

[10ebbor10]

Nah, Even at a perpendicular angle there wouldn't have been a crater. (Maybe a small field of impacts, but no more).

Yesterday its path was about 700km in atmosphere, and then it burned out.

With a perpendicular trajectory its path through dense air would be a lot shorter (70-100kms), and it would save a lot of its initial mass - to strike the ground.

Just as a note, the asteroid simply doesn't have the mass nor density nor speed to survive reentry. The breakup is nearly instantanous as soon as it reaches a certain athmospheric density, so the angle barely matters (For most of the voyage, Ie, the first 690 km, the friction was almost, but not quite, neglible). (there's a variation of about 10 km in altitude). Maybe some parts might have survived, but they wouldn't be large enough to do much damage.(Maybe obliterating a single block at most)

Besides, as it was now, the projectile never even travelled through dense athmosphere. It disintegrated between 32-50 km altitude while the densest parts of the athmosphere only reach 10 km up.

[Grax]

The difference with a steeper angle would be an airburst closer to ground.

Or simply impact.

The asteroid didn't have the size nor structural integrity nor speed to survive the reentry.

I thought "steeper" means more perpendicular, so there'd be no chance and need to reenter ;-)

If the airburst had happened at 10-15 km rather than 30-50 we wouldn't be talking about injuries from broken glass.

Though even those glass chips were the cause of more than thousand registered accidents with heavy wounds and, i think, somewhat about 20 thousands with light injuries in total.

Just as a note, there were 1400 with wounds, of which only 20 had been heavily injured.
That's what I heard.

I didn't mean severed arms/legs or guts/brains spilled out to the walls and floors. "Heavy wounds" just mean multiple wounds or deep cuts with bloodloss that need bandage and medical care.
"Light wounds" are those that everybody can cure/bandage by himself or surrounding people and won't go to medics at all.

[Il Palazzo]

If they never went to a medic, then where do you get your estimate from?