Author Topic: Meteor Strikes Chelyabinsk, Russia  (Read 136753 times)

Offline R7

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #140 on: 02/15/2013 07:23 PM »
Dare I say around 1 megaton event?

Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.
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Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #141 on: 02/15/2013 07:24 PM »
Found a video with a full length meteor going through atmosphere to shockwave impact.

Meteorite passes by at 4:40 in video.
Shockwave impact at 7:01 in video.
Thats a dramatic 2m21s in time delay, or 48km away assuming speed of sound at sea level.
The angle is also oblique as well, but we should be able to guesstimate the altitude from that.


One more full video of event allowing more accurate estimate, since the location is known:

Local time is in the low-right corner
The camera is in the northern outskirt of the city, no more than 10 km from epicenter.
First flash = 9:20:03
Second flash = 9:20:05 (major)
Shock wave = 9:22:22
Delay = 137 sec.
Now, on speed of sound - it was minus 13 C, altitude ~ 205 m. I did simple graph approximation for [0.25 -- 40 km] and got average 305 m/sec. This gives distance of 41.8 km. Assuming the range to epicenter as 10 km, the altitude of explosion was 40.6 km
Given the range of 10 km is a max estimate, I'd give the final number as 41 +/- 0.5 km



Offline jcm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #142 on: 02/15/2013 07:28 PM »
Dare I say around 1 megaton event?

Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.

New estimates based on infrasound stations (and I don't know how they
derive the result) claim 15m dia, 7000 tonnes, and hundreds of kT
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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #143 on: 02/15/2013 07:28 PM »
Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.

No way was this amount of bang produced by 0.5 KT. NASA are now estimating the diameter at 15 m and mass at about 7000 tons. http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html

Offline jcm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #144 on: 02/15/2013 07:29 PM »
I agree with Jorge's latest that it seems unrelated - unless maybe it aerobraked in the southern hemisphere unseen  and ended up making half an orbit, like an Apollo/Zond skip reentry
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Offline R7

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #145 on: 02/15/2013 07:33 PM »
No way was this amount of bang produced by 0.5 KT. NASA are now estimating the diameter at 15 m and mass at about 7000 tons.

I did wonder that 0.5kt sound low. But 7000 tons .. wow!

edit: about the mlinder second image, isn't it weird that the approximated meteor trajectory is almost straight from the sun? Things flying such orbit should have had insane velocity, no? Or maybe I just read it incorrectly.
« Last Edit: 02/15/2013 07:37 PM by R7 »
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Offline mmeijeri

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #146 on: 02/15/2013 07:35 PM »
Any idea on whether the alleged event in Cuba is real? Amusingly, there could still be a link between the Cuban event, if it happened, and either the big asteroid or the Russian meteor, but not both, now that we know that the latter two are unrelated. Or the Cuban event could be a false report, which is what Iím inclined to believe.
« Last Edit: 02/15/2013 07:35 PM by mmeijeri »
We will be vic-toooooo-ri-ous!!!

Offline kevin-rf

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #147 on: 02/15/2013 07:35 PM »
Let the hearings begin!

How quick and predictable. Talk about how important it all is until the noise of this event dies down.
So should we be bracing for a law banning Assault Meteors?
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Offline ChileVerde

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #148 on: 02/15/2013 07:53 PM »
I agree with Jorge's latest that it seems unrelated - unless maybe it aerobraked in the southern hemisphere unseen  and ended up making half an orbit, like an Apollo/Zond skip reentry

I agree that it's looking like they're unrelated, but a certain amount of wait-and-see might still be warranted. Jay Melosh was just on NPR Science Friday and was hedging a little bit on the coincidental nature of the two events.
"I canít tell you which asteroid, but there will be one in 2025," Bolden asserted.

Offline Lee Jay

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #149 on: 02/15/2013 07:55 PM »
I agree with Jorge's latest that it seems unrelated - unless maybe it aerobraked in the southern hemisphere unseen  and ended up making half an orbit, like an Apollo/Zond skip reentry

Which it couldn't do at 18km/second at the second entry, correct?

Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #150 on: 02/15/2013 07:56 PM »
Let the hearings begin!

How quick and predictable. Talk about how important it all is until the noise of this event dies down.

And maybe everybody should just stop and take a few breaths.

We could start by putting this in perspective. How many people have died in the past decade from seismic-related events? How much money is being spent to predict those?


Offline kevin-rf

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #151 on: 02/15/2013 08:00 PM »

And maybe everybody should just stop and take a few breaths.

We could start by putting this in perspective. How many people have died in the past decade from seismic-related events? How much money is being spent to predict those?


Considering the Italians just put a bunch of seismic scientists on trial for failing to predict a killer earthquake, that may be a poor example.
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Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #152 on: 02/15/2013 08:04 PM »

And maybe everybody should just stop and take a few breaths.

We could start by putting this in perspective. How many people have died in the past decade from seismic-related events? How much money is being spent to predict those?


Considering the Italians just put a bunch of seismic scientists on trial for failing to predict a killer earthquake, that may be a poor example.

It's an excellent example. But please, feel free to run around screaming if it makes you feel better...

Offline Mark S

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #153 on: 02/15/2013 08:04 PM »

And maybe everybody should just stop and take a few breaths.

We could start by putting this in perspective. How many people have died in the past decade from seismic-related events? How much money is being spent to predict those?


Considering the Italians just put a bunch of seismic scientists on trial for failing to predict a killer earthquake, that may be a poor example.

Convicted, actually, if I recall correctly.

Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #154 on: 02/15/2013 08:09 PM »
Anybody seriously interested in the issue of searching for asteroids and what to do about deflecting them from hitting Earth can check out this study from 2010:

http://www.nap.edu/catalog.php?record_id=12842

Free download.


Offline jcm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #155 on: 02/15/2013 08:09 PM »
I agree with Jorge's latest that it seems unrelated - unless maybe it aerobraked in the southern hemisphere unseen  and ended up making half an orbit, like an Apollo/Zond skip reentry

Which it couldn't do at 18km/second at the second entry, correct?

Yes, the second entry would be more like 7 km/s, but we don't actually know
what its speed was
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Offline rdale

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #156 on: 02/15/2013 08:14 PM »
Considering the Italians just put a bunch of seismic scientists on trial for failing to predict a killer earthquake, that may be a poor example.

Convicted, actually, if I recall correctly.

Part of the reason they went on trial is because they told their citizens not to bother preparing for earthquakes and enjoy a glass of wine. Totally unrelated.

Offline Robotbeat

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #157 on: 02/15/2013 08:14 PM »
What are you doing about it?

Nothing. Not a U.S. taxpayer so my opinion is inconsequential for all practical purposes.
Well, you certainly could do whatever in your own country as well. That's just as important.
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Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #158 on: 02/15/2013 08:16 PM »
Dare I say around 1 megaton event?

Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.

New estimates based on infrasound stations (and I don't know how they
derive the result) claim 15m dia, 7000 tonnes, and hundreds of kT


7000 tonnes ... "Wow" seems not enough :)
I have no idea how this estimate was obtained, but I'm sure it's beyond my expertize.

Lets compare with records --
Sikhote-Alin meteorite (belongs to the top 10 largest meteorites):
estimated mass = 70 to 100 tonnes
Recovered mass = 23 t
entry speed = 14 km/sec
more than a hundred of craters and severe damage to forest in epicenter.
It fell in unpopulated remote area, but the sound was heard 300 km away
Bright flash was seen from Vladivostok, some 450 km away.

today:
In Miass and Zlatoust (90 and 110 km to the west from Chelyabinsk) nobody heard a sound, they just enjoy a silent show.
in the epicenter - broken windows and one abundoned building damaged by shock wave.
no large craters reported so far. The only reported fragments are about 0.5 cm...
estimated entry speed 15-20 km/sec
and yet on the top, it is 7000 tonnes...

If so - it was very gentle and well behaving meteorite :)

Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #159 on: 02/15/2013 08:17 PM »
What are you doing about it?

Nothing. Not a U.S. taxpayer so my opinion is inconsequential for all practical purposes.
Well, you certainly could do whatever in your own country as well. That's just as important.

Or you could go here and donate:

http://b612foundation.org/donate/


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