Author Topic: Meteor Strikes Chelyabinsk, Russia  (Read 136465 times)

Offline iamlucky13

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #260 on: 02/16/2013 10:50 PM »
What if this thing had not been in an Earth-grazing trajectory, but had instead hit full-on, in surface-normal trajectory? Would it have smashed into the ground rather than exploding overhead?

You can play around with different sample cases at the Asteroid Impact Effects Calculator, easily one of the coolest online widget I've ever come across. According the accompanying white paper, it was created by a couple graduate students and takes into decent estimate methods from multiple academic fields related to the effects it calculates. It will, of course, still be far from perfect, but it's as good of a tool as you will find for making rough predictions:

http://impact.ese.ic.ac.uk/ImpactEffects/

From the best size estimates so far (NASA JPL), if I use 17 km/s entry speed and a 30 degree angle, it estimates a 130 kt airburst representing a little under of 1/2 the total kinetic energy at 27km altitude and only fragments reaching the surface. Pretty darn good agreement with what JPL is saying so far.

If I crank the angle up to 90 degrees, it makes it down to 18 km.

Of course, that depends heavily on its composition and coherency. A rubble pile is going to fall apart very quickly. A chunk knocked off a body that was large enough to at one point in the solar system's history be molten and therefore have cooled into a solid rock would make it a lot further down, possibly reaching the ground intact.

A solid enough meteorite most definitely can reach the ground intact, and even survive impact. The Willamette Meteorite, an iron-nickle specimen, is roughly 3m x 2m and weighs 14 tonnes - far smaller.

http://en.wikipedia.org/wiki/Willamette_Meteorite


Even if yields are the same effects of nuke would be quite different, no? Meteor dissipates it's energy during several seconds to path of several tens(?) of kilometers. Nuke releases it all in microseconds to one point. Wildly different shockwave ensues.

A bit different, but air can only transmit the energy from a nuclear blast so fast, and you end up that after traveling a certain distance, the main shockwave can be pretty similar.

Incidentally the reason why a lot of Russian news report insists heavily on "low radiation levels",   is because that unfortunate region also suffered some huge nuclear disaster back in 1957.
http://en.wikipedia.org/wiki/Kyshtym_disaster

Is it because of that, or is it because almost no one in the media understands the difference between radiation exposure (such as in space) and radioactivity, and therefore believes everything in space is radioactive?

Offline iamlucky13

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #261 on: 02/16/2013 10:55 PM »
Russian news now reporting no fragments found in lake, maybe due to hole in ice formed because of different reason, not impact.

See rt.com
This is what they posted:
18:40 GMT: The search for the meteorite parts at Chebarkul Lake and at
other two locations has officially been stopped. The huge ice hole
found at the lake on Friday “has formed because of a different reason,”
the Vice-Governor of Chelyabinsk region Igor Murog told Interfax-Ural.

The hole was found immediately after the meteor event, in the right area, with bits of dark rock similar to other meteors.

He's jumping to the conclusion that because they can't sort whatever chunks may have survived the impact from all the other rocks on the bottom of a frozen lake that therefore the hole has to have resulted from something else.

In my opinion, the evidence so far points very heavily to that hole in the ice being where a fragment landed. His conclusion is hasty.

Of course, that doesn't mean it's productive to continue searching given the conditions.

Offline asmi

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #262 on: 02/16/2013 11:00 PM »
So the world's reaction to the event can be summed up like this: "Not in our backyard". What saddens me the most that it would take a direct hit with mass casualties until pociticians in power will get their asses up and actually do something about that...

Offline Robotbeat

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #263 on: 02/16/2013 11:04 PM »
I'm scheduled for a hit on NBC Nightly tonight, with mitigation justifications....

PLEASE do a good job! Don't do what we normally do and spend the whole time talking about how rare something like this is, trying to get people not to care. You don't have to scare mongering but do a good job selling in general why it is good to have broad capabilities in science and technology so when the time comes we can be ready.
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Online ugordan

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #264 on: 02/16/2013 11:11 PM »
The timing would be coincidental, but not incredible - no doubt the meteor was still supersonic at the time of breakup, so the fragment would at first outpace the shockwave, then slow below supersonic, with the shockwave just happening to catch up to it again at about the same time it hit the ground.

In the beginning I thought it was a fragment, too, but Occam's razor suggests the much simpler explanation of the (old?) roof  collapsing due to overpressure. Keep in mind that the blast was relatively overhead so the shockwave was directed downward and there was probably no significant Mach stem effect. Vertical windows wouldn't experience the same forces a horizontal roof would.

Also technically, a fragment can't outpace a shockwave, it would produce its own shockwave instead - which would have been heard for something big enough to cave in a roof. Yet I don't see how a low ballistic coefficient object could outrun the much more massive main body mass and its shockwave and result in a weaker sonic boom before the main impact - which wasn't heard as far as I can tell, either.

Consider also that the hole in the roof is really big, I would imagine a fragment punching a more localized hole.

Most videos I've seen don't seem to do justice to the sound and power of that shockwave, ironically it's this low quality video that I think captures it best:



I have little trouble believing this kind of thing could explain the damage seen at that zinc factory.
« Last Edit: 02/16/2013 11:20 PM by ugordan »

Offline JimO

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #265 on: 02/16/2013 11:49 PM »
Feb 16,  2013 3-min piece leads the Nightly News [my wrapup at 2:40]
http://www.nbcnews.com/id/3032619/ns/NBCNightlyNews/

They used only a few direct words from me, but I spent half an hour with the producer and a lot of the narration words are mine, too.

[Feb 15 hit on CNBC: http://www.cnbc.com/id/15840232/?video=3000148418&play=1]

Offline Rocket Science

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #266 on: 02/16/2013 11:58 PM »
Feb 16,  2013 3-min piece leads the Nightly News [my wrapup at 2:40]
http://www.nbcnews.com/id/3032619/ns/NBCNightlyNews/

They used only a few direct words from me, but I spent half an hour with the producer and a lot of the narration words are mine, too.

[Feb 15 hit on CNBC: http://www.cnbc.com/id/15840232/?video=3000148418&play=1]
I liked your phrase: “caught in a cosmic crossfire” easy to visualize... Well done JimO !  :)
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Offline boaorm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #267 on: 02/17/2013 12:06 AM »
A plausible explanation for the damage at the zink factory is a dust explosion initiated by the shock wave and any ignition source inside.

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #268 on: 02/17/2013 12:53 AM »
In this video (posted previously), the shock wave arrives at 1:10. After the initial startle, the camera is then pointed at a rising cloud of smoke coming from a source hidden by a building. The smoke appears new.

See also pictures labeled 01, 02, and 03 on this page showing the zinc factory. Photo 1 shows a similar cloud of smoke as the video:
http://zyalt.livejournal.com/722930.html#cutid1

Furthermore, all of the damage I've seen so far has been broken windows, and in the worst cases, a couple doors knocked off hinges. No other structural collapses from the shock wave, but in photo 03, the bricks appear to have been scattered pretty forcefully.

So I additionally am led to speculate the zinc factory was hit by a fragment, although there appears to be no word on that yet, so my only basis is disbelief that this singular building would suffer so much worse damage than everything else.

The timing would be coincidental, but not incredible - no doubt the meteor was still supersonic at the time of breakup, so the fragment would at first outpace the shockwave, then slow below supersonic, with the shockwave just happening to catch up to it again at about the same time it hit the ground.

!

>>Photo 1 shows a similar cloud of smoke as the video
There were several fires in the city - all in industrial buildings, and all from heating oil burners damaged by shock wave. Fortunately, they were extinguished in minutes, so that were was not trouble but smoke.
NO METEORITE FRAGMENTS hit the city, all the damage is done by shock wave only.

>>So I additionally am led to speculate the zinc factory was hit by a fragment
No, it was done by shock wave. In this particular case, it is the fault of factory administration - the building was overdue for major repair. The buildings next to that one have all the windows intact. This place is approximately 7 km north from epicenter.

>>No other structural collapses from the shock wave
There are two cases in the epicenter - partial roof collapse of ChTPZ (ЧТПЗ) factory, both heavy injuries are from that place, and the second - Ice Sports Arena's canopy destroyed.

The explosion was at 40 km altitude, it was still VERY supersonic, and on very shallow trajectory. So, to hit the city the fragments would have to turn almost 90 deg - that's impossible.
All the impact sites found so far are at least 80 km from the city.
« Last Edit: 02/17/2013 12:54 AM by smoliarm »

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #269 on: 02/17/2013 01:14 AM »

In the beginning I thought it was a fragment, too, but Occam's razor suggests the much simpler explanation of the (old?) roof  collapsing due to overpressure.
You are right - the roof was not only old, it was damaged last year and not repaired. They had several warnings, but they just did not do the repair.

Quote
Also technically, a fragment can't outpace a shockwave,
Actually, it can :)

Quote
it would produce its own shockwave instead
And that's what it did :)
- in both confirmed impact sites eyewitnesses describe it exactly this way.


Offline rdale

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #271 on: 02/17/2013 01:21 AM »
So the world's reaction to the event can be summed up like this: "Not in our backyard". What saddens me the most that it would take a direct hit with mass casualties until pociticians in power will get their asses up and actually do something about that...

...which they should... More people die in one month from flooding than in a century from meteors.

Offline Nittany Lion

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #272 on: 02/17/2013 01:36 AM »
More people die in one month from flooding than in a century from meteors.


Please don’t let The Weather Channel begin naming asteroid flybys.



Online kevin-rf

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #273 on: 02/17/2013 01:57 AM »

Please don’t let The Weather Channel begin naming asteroid flybys.


Why, I think Jim would be a great name ;)

btw. On the humorous side the onion has a cool write-up http://www.theonion.com/articles/more-than-1000-russians-injured-in-freaking-cooles,31321/
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Offline asmi

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #274 on: 02/17/2013 02:02 AM »
...which they should... More people die in one month from flooding than in a century from meteors.
It will take just one "good" hit to turn this statistics upside down. And while the specific town/towns can theoretically be evacuated in time for the event, imagine that tomorrow it is discovered that 1000 meter asteroid is coming our way - what are we going to do about that? We can't evacuate the whole continent, not to mention the whole planet...

Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #275 on: 02/17/2013 02:07 AM »
If the cost is $500M, it would seem reasonable considering that NASA has a $17B per year budget. This is the kind of work that NASA is expected to do. If NASA doesn't do this kind of work, taxpayers will eventually question whether their $17B per year "investment" into NASA is put to good use.
The result is that the money has gotten cut out of other things at NASA, and the agency has never really had the resources to accomplish it.

This is just a variation of the common situation of the "unfunded mandate."

In your opinion, is this likely to change given the close pass and Russian impact?

Yeah, probably. But probably only a little bit. To cut to the chase, the US government right now is so dysfunctional that it may not be possible for anything to change, even if it should. If government was properly working, what should happen is that the administration would tie its stated goal of sending humans to an asteroid--for which they are not spending any money--to this new concern and add some money to NASA's budget to fund a space-based survey telescope. (My own view is that they should simply fund the NEOCam Discovery mission proposal. It is not the best way to do the job, but it is probably the most cost effective and least expensive.)

But gazing into my cracked crystal ball, here is likely what is going to happen: Congress will hold hearings, they may put some additional language into a NASA authorization bill (one is supposedly in the planning stages), and they may increase the tracking requirement. They may also call for another study of the issue. (That's not a totally bad idea, although I'd suggest that a smarter thing to do would be to implement some of the recommendations in the last NRC study of the issue.) But the authorization bill will not come with additional money attached, and it will be up to the appropriators and the White House to step forward. They _might_ do that. In fact, the White House has been trying to increase the NEO budget for a few years now (from $6 million to about $20 million)--although nobody I know seems to know where that money is supposed to go. But I refer you back to the "government is broken" stuff above. Currently there is language in the NASA authorization act that calls for detection of 140-meter objects that the administration is not funding. Congress can increase the requirement all it wants and the administration can keep ignoring it.

I think that one thing that doesn't help a lot is that Rohrabacher is the loudest voice on this subject. He's liked by some space enthusiasts, but he's not treated with much respect by his peers. If you watch the hearings in which he participates, it is clear that many of his colleagues don't take his lead. If a more well-respected member of Congress took on this issue it would have better chances. But broken government, there you go.

Offline Nittany Lion

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #276 on: 02/17/2013 02:08 AM »

Please don’t let The Weather Channel begin naming asteroid flybys.


Why, I think Jim would be a great name ;)



If I die from Asteroid Jim I’m gonna be so upset!



Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #277 on: 02/17/2013 02:21 AM »
I should add that there's something that Congress could do in an authorization bill that would be worthwhile and would not cost (much) money. They could require DoD to share the data it has recorded on infrared events in the upper atmosphere with scientists who possess the appropriate security clearances. US missile warning satellites regularly record the reentry of space debris as well as meteors. But that data is not made available to the asteroid tracking community so that they can validate their models on how much material enters the atmosphere. That would be a useful thing for them to do.

Offline lcs

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #278 on: 02/17/2013 02:39 AM »
The timing would be coincidental, but not incredible - no doubt the meteor was still supersonic at the time of breakup, so the fragment would at first outpace the shockwave, then slow below supersonic, with the shockwave just happening to catch up to it again at about the same time it hit the ground.

Most videos I've seen don't seem to do justice to the sound and power of that shockwave, ironically it's this low quality video that I think captures it best:



I have little trouble believing this kind of thing could explain the damage seen at that zinc factory.

To my ear on this video there sounds like a precursor to the shock wave, about 2 seconds before the blast hits.  Been scratching my head over what that is.  Precursors have been noted around nuclear detonations (but with much higher overpressures in the main blast).  Also on several Russian handheld videos I noticed erratic camera movements just a half-second or so before the sound hits. 
« Last Edit: 02/17/2013 02:51 AM by lcs »

Online kevin-rf

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #279 on: 02/17/2013 02:58 AM »
I should add that there's something that Congress could do in an authorization bill that would be worthwhile and would not cost (much) money. They could require DoD to share the data it has recorded on infrared events in the upper atmosphere with scientists who possess the appropriate security clearances. US missile warning satellites regularly record the reentry of space debris as well as meteors. But that data is not made available to the asteroid tracking community so that they can validate their models on how much material enters the atmosphere. That would be a useful thing for them to do.

I wonder if part of the reason they no longer share the data (apart from general paranoia) is sharing the data lets an adversary characterize the lower limits and sensitivity of the system along with maybe the scan rate and any coverage gaps that may (or may not) exist. The way around this would be to set a lower limit on what events they share and maybe degrade the data somewhat. So you don't share a 0.1 meter rock, you only do the events that are not large enough to be missed. The 1000 meter rocks ;)
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