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INCOMING!: метеорита в Челябинске, Russian Meteor - February 2013
volcanopele
post Feb 15 2013, 07:01 AM
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Looks like a small meteoroid decided to spoil 2012 DA14's big day by exploding over Russia...

http://zyalt.livejournal.com/722930.html?nojs=1


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Explorer1
post Feb 15 2013, 07:18 AM
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Depends on one's definition of 'small'! Phil Plait has an early summary/videos: http://www.youtube.com/watch?feature=playe...p;v=rflTN4XAt34
The biggest over a populated area in a long time...
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Fran Ontanaya
post Feb 15 2013, 08:16 AM
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Some info:

http://rt.com/news/meteorite-crash-urals-chelyabinsk-283/

http://rt.com/news/russia-meteor-meteorite...helyabinsk-291/
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nprev
post Feb 15 2013, 08:27 AM
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Clearly a major event. I hope that the reported injuries are mild, and that there are no fatalites.

Caution all to be objective (as all have been thus far) and most of all respectful since there does seem to be a possibility of direct effects on people here, okay?

All that being said: There is no amount of 'wow' I can adequately express. Looking forward to the final analysis of this.


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Explorer1
post Feb 15 2013, 08:43 AM
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Direct hit on factory? http://www.youtube.com/watch?v=DgZ0aA7RUhE

Crews clearing rubble like just another day at work. i know that statistically Russia is the most likely country to get hit since it's got the greatest surface area, but literally a half day before this other rock is a real coincidence.
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machi
post Feb 15 2013, 11:15 AM
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Chelyabinsk's bolid from Meteosat.


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nprev
post Feb 15 2013, 11:50 AM
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QUOTE (Explorer1 @ Feb 15 2013, 12:43 AM) *
Russia is the most likely country to get hit since it's got the greatest surface area, but literally a half day before this other rock is a real coincidence.


And that's in fact what it is precisely. Preliminary reports indicate that the object entered from a completely different azimuth than what would be possible for something associated with that asteroid during the upcoming encounter.


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belleraphon1
post Feb 15 2013, 01:01 PM
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WOW!...

Hope injuries not serious.

Analysis of this should be fascinating.... a mini-Tunguska.


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dvandorn
post Feb 15 2013, 01:10 PM
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The best of the videos I've seen show the contrail ending well above the ground, suggesting that the impactor disintegrated in the air. I'm wondering whether the bolide actually hit the ground, or whether the damage was caused by an over-pressure wave pushed ahead of it.

-the other Doug


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dilo
post Feb 15 2013, 01:26 PM
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An hour ago, Italian television told about russain military attempt to intercept/destroy the meteorite in flight, through a non-armed missile... I am very skeptical, did someone heared such a story? They showed also an impressive video with a ground explotion near an highway (metoerite fragment hitting ground?)


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machi
post Feb 15 2013, 03:33 PM
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Dilo, today's SAMs cannot hit and destroy such asteroid. Radar has limited range and limited reaction time and even ABM missiles cannot cope with object with speed more than ~7 km/s. It's total nonsense.


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dilo
post Feb 15 2013, 03:46 PM
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Yes, machi, I know and I said I was skeptical! in fact, it seems such rumor was officially denied...


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TheAnt
post Feb 15 2013, 03:56 PM
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QUOTE (dvandorn @ Feb 15 2013, 02:10 PM) *
The best of the videos I've seen show the contrail ending well above the ground, suggesting that the impactor disintegrated in the air. I'm wondering whether the bolide actually hit the ground, or whether the damage was caused by an over-pressure wave pushed ahead of it.

-the other Doug


Several pieces did hit the ground, images of that factory shown above is only one that might have been a smaller piece.
A somewhat larger impacted near a highway.
And one piece thought to have been larger is said to have ended up in a lake quite far from the city according to my teletext news here.

@dilo: Hard to say, my teletext feed states that there initially were one alert for one possible nuclear strike, but it reads as that alert came after the actual impact so I guess the Italians have elaborated on that fact a bit.

@nprev: The teletext say about 900 wounded, mostly from shattered glass, and a number (no numbers given) hospitalized. But still no mention of any casualties so lets hope there were none.
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Phil Stooke
post Feb 15 2013, 04:05 PM
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The story about intercepting the meteorite is almost certainly a journalist's confusion between the current event and stories about future asteroid deflection missions, which are being discussed in Russia.

Phil





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Mongo
post Feb 15 2013, 04:08 PM
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I am trying to get an estimate of the size of the meteoroid and explosion. Assuming a dense rocky composition with a density around 3 tonnes per cubic metre, I keep getting sizes much larger than the estimate of around 10 tonnes that I have heard. The calculation below results in a mass of around 73,000 tonnes.

The overpressure from the blast wave was sufficient to shatter thousands of windows (and in fact some videos I have watched appear to show that every window in view was smashed) and caused the partial collapse of a zinc factory. This implies that the overpressure was between 1 kPA (shatters many windows) and 5 kPa (partial collapse of some buildings), let's assume that the zinc factory was poorly maintained and the overpressure was 3 kPa.

Early reports give an entry velocity of around 30 km/s.

According to this site, the diameter of a rocky object that produces a 3.1 kPa overpressure at a distance of 30 km from directly under the main explosion (as appears to be roughly the distance from the videos) would be about 36m, producing a 5.26 MT airburst at an altitude of 18.2 km.

Earth Impact Effects Program
Robert Marcus, H. Jay Melosh, and Gareth Collins

Please note: the results below are estimates based on current (limited) understanding of the impact process and come with large uncertainties; they should be used with caution, particularly in the case of peculiar input parameters. All values are given to three significant figures but this does not reflect the precision of the estimate. For more information about the uncertainty associated with our calculations and a full discussion of this program, please refer to this article

Your Inputs:
Distance from Impact: 30.00 km ( = 18.60 miles )
Projectile diameter: 36.00 meters ( = 118.00 feet )
Projectile Density: 3000 kg/m3
Impact Velocity: 30.00 km per second ( = 18.60 miles per second )

Energy:
Energy before atmospheric entry: 3.30 x 10^16 Joules = 7.88 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 539.1 years

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).
The impact does not shift the Earth's orbit noticeably.

Atmospheric Entry:
The projectile begins to breakup at an altitude of 63100 meters = 207000 ft
The projectile bursts into a cloud of fragments at an altitude of 18200 meters = 59600 ft
The residual velocity of the projectile fragments after the burst is 17.3 km/s = 10.7 miles/s
The energy of the airburst is 2.20 x 10^16 Joules = 5.26 MegaTons.
No crater is formed, although large fragments may strike the surface.

Air Blast:
The air blast will arrive approximately 1.77 minutes after impact.
Peak Overpressure: 3100 Pa = 0.031 bars = 0.44 psi
Max wind velocity: 7.21 m/s = 16.1 mph
Sound Intensity: 70 dB (Loud as heavy traffic)

edit -- Assuming that the distance from ground zero was 15km instead of 30km, and with an overpressure of 2 kPa, the website gives the following (calculated initial mass 51,000 tonnes):

Your Inputs:
Distance from Impact: 15.00 km ( = 9.32 miles )
Projectile diameter: 32.00 meters ( = 105.00 feet )
Projectile Density: 3000 kg/m3
Impact Velocity: 30.00 km per second ( = 18.60 miles per second )

Energy:
Energy before atmospheric entry: 2.32 x 10^16 Joules = 5.53 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 410.7 years

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).
The impact does not shift the Earth's orbit noticeably.

Atmospheric Entry:
The projectile begins to breakup at an altitude of 63100 meters = 207000 ft
The projectile bursts into a cloud of fragments at an altitude of 19900 meters = 65400 ft
The residual velocity of the projectile fragments after the burst is 18.3 km/s = 11.4 miles/s
The energy of the airburst is 1.45 x 10^16 Joules = 3.47 MegaTons.
No crater is formed, although large fragments may strike the surface.

Air Blast:
The air blast will arrive approximately 1.26 minutes after impact.
Peak Overpressure: 2120 Pa = 0.0212 bars = 0.301 psi
Max wind velocity: 4.96 m/s = 11.1 mph
Sound Intensity: 67 dB (Loud as heavy traffic)

another edit -- this is the minimum value that reliably breaks windows, it still results in a calculated airburst energy of 1.9 MT with an initial mass of 31,000 tonnes. I doubt that the airburst was this close to overhead, it appeared closer to the horizon in the videos.

Your Inputs:
Distance from Impact: 10.00 km ( = 6.21 miles )
Projectile diameter: 27.00 meters ( = 88.60 feet )
Projectile Density: 3000 kg/m3
Impact Velocity: 30.00 km per second ( = 18.60 miles per second )

Energy:
Energy before atmospheric entry: 1.39 x 10^16 Joules = 3.32 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 277.4 years

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).
The impact does not shift the Earth's orbit noticeably.

Atmospheric Entry:
The projectile begins to breakup at an altitude of 63100 meters = 207000 ft
The projectile bursts into a cloud of fragments at an altitude of 22500 meters = 73700 ft
The residual velocity of the projectile fragments after the burst is 19.6 km/s = 12.2 miles/s
The energy of the airburst is 7.95 x 10^15 Joules = 1.90 MegaTons.
No crater is formed, although large fragments may strike the surface.

Air Blast:
The air blast will arrive approximately 1.24 minutes after impact.
Peak Overpressure: 994 Pa = 0.00994 bars = 0.141 psi
Max wind velocity: 2.33 m/s = 5.22 mph
Sound Intensity: 60 dB (Loud as heavy traffic)
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