Author Topic: Meteor Strikes Chelyabinsk, Russia  (Read 136659 times)

Offline majormajor42

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #280 on: 02/17/2013 03:04 AM »
aerial photo:
@AstroTerry
Quote
A friend sent me this from Russia, a pilot took a pic of the#RussianMeteor from the cockpit. Amazing! pic.twitter.com/v3gkBjfo10:11am - 16 Feb 13

...water is life and it is out there, where we intend to go. I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man or machine on a body such as the Moon and harvest a cup of water for a human to drink or process into fuel for their craft.

Offline jcm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #281 on: 02/17/2013 03:04 AM »

Please donít let The Weather Channel begin naming asteroid flybys.


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



If I die from Asteroid Jim Iím gonna be so upset!




I'm glad mine is safely in the main belt, how embarrassing would it be for your name to be forever associated with an extinction event? 

Very interesting about the zinc factory and the other secondary effects
from the shock wave.

It seems like the California, Cuba and Japanese fireballs are all small and just regular background events that are  being noticed because fireballs are in the news.

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Offline GM4BRB - 5DecadesinSpace

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #282 on: 02/17/2013 03:44 AM »

[...]

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.

Thanks for this. I was unable to get to sleep still cogitating on the fact I didn't remember anyone saying at what altitude the Meteor exploded. I also noted that early posts seemed to infer that it was Supersonic Fragments causing the Blasts. It's clear that this was a blast from an airburst.

Trawling through Youtubes I settled on about 2 mins between the fireball and the arrival of the sonic-blasts, though it's really hard to find continuity in any of the vids. However, 2 mins delay would equate to 40km already seeing Speed of sound in air = 330m/s-1 approx.

Спасибо и до свидания на данный момент.
« Last Edit: 02/17/2013 04:12 AM by GM4BRB - 5DecadesinSpace »

Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #283 on: 02/17/2013 04:13 AM »
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 ;)

I'm not sure that they ever regularly shared the data. In the mid-1990s or so Pete Worden, then in the USAF (not sure if he had gotten his star yet) managed to get some data shared. But apparently this was a single time thing and not a regular occurrence. I think that they don't share the data not because of any particular secrecy concerns, but because they don't have to, nobody has made them do it, and they don't see any reason that they should.

And there is no real security concern that cannot be addressed with proper safeguards. There are lots of scientists who get security clearances and are allowed access to very sensitive data. They have to scrub it and get permission to publish, but there are procedures for doing this. For instance, reconnaissance satellite photos have been used to count seals in the Arctic and whales at sea because scientists got clearances. I know a guy who had solar radiation sensors mounted on DSP satellites, whose locations were classified information. In the case of the IR warning data, they could simply set a threshold and say "you cannot comment on anything below X." Or they could preserve the security aspects by binning the data, so that they could say that there were Y number of events below threshold X, but not indicating how many of them were way below that limit. It should be solvable, it just requires somebody willing to do it.

This event might cause some people to wake up about this issue.
« Last Edit: 02/17/2013 04:14 AM by Blackstar »

Offline kevin-rf

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #284 on: 02/17/2013 04:40 AM »
Didn't realize that was a one time event, I thought they had been sharing up to some point in the recent past when they stopped. Thanks for the backstory.
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Online sanman

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #285 on: 02/17/2013 04:53 AM »
aerial photo:
@AstroTerry
Quote
A friend sent me this from Russia, a pilot took a pic of the#RussianMeteor from the cockpit. Amazing! pic.twitter.com/v3gkBjfo10:11am - 16 Feb 13

Wow - that's pretty cool. Was that pic taken around the same time the actual explosion occurred? How would the plane have been affected by being in the air when that happened? Wouldn't it have been hit by the shockwave and have lost control?

Offline iamlucky13

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #286 on: 02/17/2013 05:02 AM »
Quote
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.

It would produce a smaller shockwave than the airburst event. The shockwave from a supersonic fragment probably less than a meter in size probably wouldn't propagate 20+ km, and would utterly pale in comparison to the 500 kT of energy estimate to have been released to the atmosphere by the main disintegration.

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.

Since you're from Russia, I will take your word as having more thorough news coverage than the English sources can provide.

Quote
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.

I was only speculating before, but your reference to the distance downrange for other impacts convinces me.

The smoke trail certainly appeared to point much further downrange, but getting an accurate perspective of the angle of distant lines is hard enough with stable videos. I didn't trust my eyes on that one.

Online sanman

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #287 on: 02/17/2013 05:09 AM »
So how much material could be recoverable from this meteor hit?

I was reading that there's a big rush to gather pieces and sell them for cash:

http://abcnews.go.com/International/russian-meteor-rushing-cash-blast/story?id=18522807

Offline 360-180

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #288 on: 02/17/2013 06:14 AM »
So how much material could be recoverable from this meteor hit?

I was reading that there's a big rush to gather pieces and sell them for cash:

http://abcnews.go.com/International/russian-meteor-rushing-cash-blast/story?id=18522807
"Authorities have sent divers into a frozen lake outside the city, where a large chunk of the meteor is believed to have landed, creating a large hole in the ice. By the end of the day they had not found anything."
large hole in the ice made by fishermen ;D

bolid trace from plane at 34000 ft level
« Last Edit: 02/17/2013 11:11 AM by 360-180 »

Offline ugordan

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #289 on: 02/17/2013 10:55 AM »
The shockwave from a supersonic fragment probably less than a meter in size probably wouldn't propagate 20+ km

I don't know why you conclude that since small bolides have been known to produce very audible sonic booms indicating that such shockwaves can readily propagate to the ground. We're talking about a highly, not marginally supersonic object which carries a lot of energy and is rapidly slowed down. That energy has to go somewhere.

Offline Zan Tiala Thraeki Dica

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #290 on: 02/17/2013 11:32 AM »
Do you know that if we follow the strait direction of Chelyabinsk asteroid through Earth we find out the Eastern Island? Does anyone measured the asteroid impact on Earth's crust ?

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #291 on: 02/17/2013 11:48 AM »
...
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.

Since you're from Russia, I will take your word as having more thorough news coverage than the English sources can provide.

...

You are lucky indeed you have not read Russian news on this subject :) The amount of nonsense is incredible.
Of course, my info is NOT from the news, here are the sources (sorry I did not give them in the first place):
OF FIRES - firefighter's reports from the first day;
BUILDING DAMAGE - 1. Major's office reports and 2. School District Office reports. Interestingly, elementary school principals produced more accurate and FAST reports - by FAR, compared to other offices :)
IMPACT CRATERS and SITES (search and confirmations) - Emergency HQ press-conference transcripts and private communications.

With respect to some statements from officials that no meteorite material found -
The officials have to deal now with one more real trouble: hundreds (or thousands) of meteorite hunters. So, it is my guess that they do not release any info on fragment found intentionally. And it's quite wise, they can't secure impact sites properly, all the police and emergency crews are busy fixing the windows (it was -20 C last night).

Finally, about the altitude of explosion - it is from my calculation described here
http://forum.nasaspaceflight.com/index.php?topic=31118.msg1013503#msg1013503
(I used average speed of sound of 305 m/sec, estimate from this graph http://en.wikipedia.org/wiki/File:Comparison_US_standard_atmosphere_1962.svg)
One of my students did the same kind calculation on different surveillance recording, with the same result:
Altitude of explosion = 41 Ī 0.5 km
Another student went different way - she collected videos and pictures from KNOWN locations  20 to 150 km away, made from different directions (from West to SE). She made classic triangulation, trying to correct for focal length of lenses using naturally strait lines in view (buildings, roads, wires etc.) I was pretty skeptical, but she got 44 Ī 5 km in the end :)



Offline RichardAKJ

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #292 on: 02/17/2013 11:53 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.

Many thanks for your reply, Blackstar. Very informative.

Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #293 on: 02/17/2013 12:34 PM »
So how much material could be recoverable from this meteor hit?

I was reading that there's a big rush to gather pieces and sell them for cash:

http://abcnews.go.com/International/russian-meteor-rushing-cash-blast/story?id=18522807
Unfortunately, that's true about big rush :)

It is difficult to tell what is the recoverable fraction - even in the cases of well observed fall and immediately discovered impact site, we never know for sure the original size. I can only give some historic cases
Sikhote-Alin -- ca. 23 tonnes recovered / ca. 100 tonnes est. before entry.
Allende -- 2 tonnes recovered / ca. 15-20 tonnes est. before entry.

It is believed, that for large meteorite (tonne scale) regardless of entry mode at least 2% of original mass fell on the ground (Monica Grady). Richard Hutchison gives higher estimate - 5% - for entry velocity below 15 km/sec.

So, IF we believe the voiced estimate of 7000 tonnes - there are some 140 tonnes of fragments waiting for meteorite hunters :)
IF this estimate turns out to be be realistic - this is the largest meteorite BY FAR in the entire world history. I am looking forward for the next Meteoritics issue with article on details on this estimate. If there will be no such article, it was a joke :)

Little grain of salt: I calculated a minimal amount of smoke produced by 7000 t chondrite assuming 75% of material goes to smoke, @ 40 km altitude @ pressure of 0.003 atm. I ended with ca 20 cubic km of dense smoke. And it does not look like we see it:
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=31118.0;attach=495901;image

Offline Blackstar

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #294 on: 02/17/2013 01:06 PM »
Anybody checked eBay to see if anybody is trying to sell what they claim are pieces of the meteorite yet?

I bet there will be a lot of scams going on very soon.

Offline ChileVerde

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #295 on: 02/17/2013 01:08 PM »
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 ;)

http://science.slashdot.org/story/09/06/22/1625254/us-military-blocks-data-on-incoming-meteors

Edit: Adds report that the data was going to be unblocked. That doesn't seem to have happened.

Quote

http://blogs.nature.com/news/2009/07/post_30.html

Air Force to resume meteor data sharing

06 Jul 2009 | 16:27 GMT | Posted by Geoffrey Brumfiel

Space.com is reporting that the United States Department of Defense (DOD) is rethinking a decision that cut off astronomers from access to data on incoming meteors.

The DOD has collected the data with a network of satellites and sensors designed to detect atmospheric nuclear detonations. The same sensors can spot a meteor streaking across the sky, and for over a decade, the military has provided astronomers with some of that data on an ad-hoc basis.

As we reported <http://www.nature.com/news/2009/090612/full/459897a.html>, that relationship came to a screeching halt earlier this year, when in March, a memo from Air Force Space Command, which operates the satellites, cautioned against sharing data with scientists. The decision was apparently made because DOD officials were worried that the data could reveal details of the US monitoring system.

But now, Brigadier General Robert Rego, the space commandís mobilization assistant to the director of air, space and nuclear operations, says that the organization is considering once again sharing data with scientists, albeit in a more carefully vetted way. The new process will be faster, more systematic, and it in compliance with classification procedures, he says. It could begin within the next few months.

Even more edit: Rohrabacher was paying attention in 2009; perhaps he'll have something to say now.

Quote
http://www.space.com/6927-military-seeks-common-ground-scientists-fireball-data-flap.html

Military Seeks Common Ground with Scientists on Fireball Data Flap
by Leonard David, SPACE.com's Space Insider Columnist
Date: 03 July 2009 Time: 03:10 PM ET

<much snip>

The flare up about the fireball data release policy has received the attention of U.S. Congressman Dana Rohrabacher, the California lawmaker with a long-time passionate interest in the entire Near Earth Object issue.

"I have been keeping a close eye on this situation, and I am confident the Department of Defense, in cooperation with the scientific community, will find a solution that permits the release of scientifically valuable data without compromising national security," Rohrabacher explained in a statement to SPACE.com.

As for a message to the scientific community, Brigadier General Rego emphasized that there was no intent, and in fact, no change to the data sharing policy. Now underway is a fresh look at ways to improve the relationship and data flow to make it more valuable to scientists.

"I would encourage you to keep your eye out or your ear to the ground with the scientific community...to see if we haven't done some improvements here over the next few months," Rego concluded.
« Last Edit: 02/17/2013 02:35 PM by ChileVerde »
"I canít tell you which asteroid, but there will be one in 2025," Bolden asserted.

Offline JimO

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #296 on: 02/17/2013 01:28 PM »
I would also be very interested in eyewitness reports of electrophonic sound PRIOR to the acoustic shock -- that is, during the brightest flaring of the fireball. This is a at-long-last well-established effect of plasma-generated radio noise coupling into near-observer physical objects and creating a hissing or whooshing sound. It occurs simo with the visual flares, seems to come from 'all around' [not from above], has been reported for centuries by some bright fireball witnesses and pooh-poohed by scientists until work by Colin Keay and others established its validity. 

Offline alexterrell

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #297 on: 02/17/2013 01:32 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...

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

I would suspect, if you don't live in a flood prone area, you have a higher probability of dying in a meteor impact than in a flood.

It's just unlikely to happen in this Parliament / Presidential Term etc.

If the Chelyabinsk event had been just a little larger, or made of iron, perhaps Russian citizens would be wondering why one of the World's most capable space nations allowed a City to be destroyed.
 

Offline ugordan

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #298 on: 02/17/2013 01:37 PM »
If the Chelyabinsk event had been just a little larger, or made of iron

What difference would it have made if it was made of iron? Might have not fragmented as easily and hence carried more of its energy downrange, away from Chelyabinsk and into some remote crater.

Edit: unless you were thinking same diameter, not same mass?
« Last Edit: 02/17/2013 01:41 PM by ugordan »

Offline 360-180

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #299 on: 02/17/2013 01:40 PM »
I used average speed of sound of 305 m/sec,
The shortest period between the flash and the shock wave in the video is 89 seconds. Based on this video, you can calculate the height of the explosion is 0.305x89=27.15 km
« Last Edit: 02/17/2013 01:44 PM by 360-180 »

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