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TravisD
2013-Feb-15, 06:15 AM
It seems a large meteor has just fallen near Moscow.

www.channelnewsasia.com/stories/afp_world/view/1254424/1/.html


Anyone got any more info?

Scriitor
2013-Feb-15, 06:37 AM
Over the Urals, actually. There are already some good videos on Youtube.

http://www.youtube.com/watch?v=MwzYnJ5rIjw

http://www.youtube.com/watch?feature=player_embedded&v=C9TWZ82zqJY

http://www.youtube.com/watch?feature=player_embedded&v=w6uOzFo2MQg

http://www.youtube.com/watch?feature=player_embedded&v=OccmX0PRJoU

Hows about that sonic boom!

Scriitor
2013-Feb-15, 06:56 AM
This one appears to show it entering the atmosphere:

http://www.youtube.com/watch?v=7c-0iwBEswE&feature=youtu.be

TravisD
2013-Feb-15, 09:46 AM
Crazy. It sounds just like the meteor that entered the atmosphere above my town about a year ago.

novaderrik
2013-Feb-15, 11:08 AM
http://rt.com/news/meteorite-crash-urals-chelyabinsk-283/

apparently they shot it down with missiles..
really, they did.. it's on the internet..

Tog
2013-Feb-15, 11:28 AM
According to unconfirmed reports, the meteorite was intercepted by an air defense unit at the Urzhumka settlement near Chelyabinsk. A missile salvo blew the meteorite to pieces at an altitude of 20 kilometers, local newspaper Znak reports quoting a source in the military.

Regnum news agency quoted a military source who claimed that the vapor condensation trail of the meteorite speaks to the fact that the meteorite was intercepted by air defenses.

I would have bet you were kidding.

Solfe
2013-Feb-15, 12:38 PM
Is this the same story: http://www.reuters.com/article/2013/02/15/uk-russia-meteorite-idUSLNE91E00G20130215

People were hurt? EDIT - the headline says injuries, but the story does not.

Edit 2 - It looks like broken glass and such. I found another story with pictures of some of the injured.

eburacum45
2013-Feb-15, 12:40 PM
If anyone thinks that they had enough time to launch a missile they are mistaken. There is no evidence in those clips that anything (apart from the Earth's atmosphere) had any effect on the meteor. It looks like it broke up tens of kilometres above their heads, and the shock wave took a considerable time to reach the observers.

I'd guess that many, if not most, of the injuries were caused by flying glass; it just goes to show that you should avoid staring out of a window when a shock wave is on its way.

kzb
2013-Feb-15, 12:48 PM
You've got to wonder if this is connected to 2012 DA14. Is it possible this meteor was a satellite of this asteroid, maybe some rubble blown off in a past impact, and that there could be more to come?

eburacum45
2013-Feb-15, 12:51 PM
I'd guess that this is unlikely to be the case, but it might be best to wait for an analysis of the trajectory. Meteor-watchers are getting quite good at working out the past orbits of these things nowadays.

Tog
2013-Feb-15, 01:04 PM
You've got to wonder if this is connected to 2012 DA14. Is it possible this meteor was a satellite of this asteroid, maybe some rubble blown off in a past impact, and that there could be more to come?

From Phil's Blog (http://www.slate.com/blogs/bad_astronomy/2013/02/15/breaking_huge_meteor_explodes_over_russia.html):

I’m trying to piece together what happened from the videos. First of all, I do not think this is related in any way to the asteroid 2102 DA14! For one thing, this occurred about 16 hours before DA14 passes. At 8 kilometers per second that’s nearly half a million kilometers away from DA14. That puts it on a totally different orbit.

Solfe
2013-Feb-15, 01:10 PM
It amazes me how hardy people are when compared to structures. I have no idea if any of the people in the videos were hurt, but they seem relatively unaffected by the shock that blew out windows. Maybe I watch too much TV.

When I was a kid, a gas explosion cracked the windows on the front of our house at 3 am. My sister slept through it even though she was closest to the broken glass. Many of our neighbors closer to the explosion actually had flying glass. In my mind, I am trying to scale that up, but it boggles my brain.

Tog
2013-Feb-15, 01:20 PM
Here's a site (http://io9.com/5984483/a-meteor-just-exploded-over-russia) with some good clips. The second one down has some CCTV footage from inside an office and warehouse (clips 2 and 3). In clip 2, I'm not sure how much was shock wave and how much was stagger, but the desk he fell into moved.

Another clip I saw panned back and above to reveal what looked like a glass window front just before the boom. I don't speak Russian, but I'm guessing from the pitch and tone that it would be a violation here. That was the only one I've seen where I fear a little for the guy with the camera. The up loaded video should mean he's either fine, or has really cold friends.

Buttercup
2013-Feb-15, 01:54 PM
Opened Twitter, saw the news. :-o

I dunno, I'm thinking this does relate to today's passing asteroid. That's the first thought which crossed my mind.

Of course it's up to scientists to determine that. I'm seeing "no, not related" and "maybe."

Don Alexander
2013-Feb-15, 02:00 PM
Man, this is incredible.

So, how often do bolides like this hit the Earth? Once a year? Most of course over open water or the vast swathes of lightly populated land. To have it happen over a major city is remarkable.

Thank the Russians for their dash cams.

Did you see the hole in the wall of that Zinc factory? Maybe they can recover the meteorite, sell it and repair their factory with the money. ;)

Also, I'm quite sure a lot of those videos have "BEEP!" at certain places if they show them in Russian television! :D

@Buttercup: Definitely not related, the asteroid is coming from below the ecliptic, this came from above and at a lower inclination.

Solfe
2013-Feb-15, 02:10 PM
Here's a site (http://io9.com/5984483/a-meteor-just-exploded-over-russia) with some good clips. The second one down has some CCTV footage from inside an office and warehouse (clips 2 and 3). In clip 2, I'm not sure how much was shock wave and how much was stagger, but the desk he fell into moved.


In clip two, I am kind of surprised that guy wasn't hurt really bad. His face was right next to the window. The next image of the garage door blowing in definitely would have hurt someone, if they had been right there.

If this had happened here, I can easily picture myself looking out the window to see what the flash was.

Geeze.

Launch window
2013-Feb-15, 02:55 PM
very impressive links, thanks for the updates and informative posts

Ara Pacis
2013-Feb-15, 03:30 PM
I'm just glad they didn't launch nukes in response thinking it was a HEMP attempt.

mantiss
2013-Feb-15, 05:32 PM
Man, this is incredible. So, how often do bolides like this hit the Earth? Once a year? There was a clip earlier with Neil Degrasse-Tyson who was saying that bolides of that magnitude strike about once a decade (ymmv) of course you would expect 7/10 times over water, and for the remainder 2/3 times over sparsely populated areas (Greenland comes to mind as there was a smaller similar events a few years back)

jfribrg
2013-Feb-15, 06:03 PM
Three comments :

1)I don't see anything yet about an estimate on the size. I'm guessing it's somewhere in the range of 5 meters in diameter, but that's really just a guess based on the estimate that the Tungaska meteorite was 100 meters in diameter. Assume that the velocity is the same, and a factor of 20, and you get something around 10 -20 kilotons equivalent in last night's explosion. Considering the damage that was sustained tens of kilometers away, that's not an unreasonable number IMO.

2) The idea that shooting it down would make any difference is laughable. The energy in the rock has to go somewhere, regardless of whether a missle hit it or not.

3) I really wish that the scientists who said there is no connection to today's asteroid flyby would wait until we're certain. If it is eventually determined that the two were connected ( perhaps both remnants of the same comet) it makes the scientific community look inept. What's so hard about saying that the two events are probably a coincidence but nothing definitive can be said until the trajectory can be determined. Of course that may be what the scientists said, but it was reported differently.

Tog
2013-Feb-15, 07:14 PM
A weather satellite caught the dust track (http://www.youtube.com/watch?v=VdoKEFsemvw&list=HL1360955516) and it was from northeast to south west. The asteroid is moving basically south to north from what I understand.

The only estimate on size I've seen said around 1 meter, but bits did make it the ground and one left a 6 meter crater.

Tog
2013-Feb-15, 07:39 PM
Actually, I just saw a Tweet from NASA that said it was 15 meters in diameter before contact with the atmosphere.

Ilya
2013-Feb-15, 08:08 PM
It amazes me how hardy people are when compared to structures. I have no idea if any of the people in the videos were hurt, but they seem relatively unaffected by the shock that blew out windows. Maybe I watch too much TV.
That does not mean people are "hardy compared to structures". People are hardy compared to glass. Which should not be surprising.

BTW, Russian government already issued a statement that no "shooting down" was involved.

NEOWatcher
2013-Feb-15, 08:13 PM
http://rt.com/news/meteorite-crash-urals-chelyabinsk-283/

apparently they shot it down with missiles..
really, they did.. it's on the internet..
That's a good example of how fast rumors fly in the media early on in an event.

Interesting reasoning...

Regnum news agency quoted a military source who claimed that the vapor condensation trail of the meteorite speaks to the fact that the meteorite was intercepted by air defenses.
I don't know how that could be a sign.



It is believed that if the Tunguska event had happened 4 hours later, due to the rotation of the Earth it would have completely destroyed the city of Vyborg and significantly damaged St. Petersburg.
But Earth would be over 400,000 km away by then... :rolleyes:

Squink
2013-Feb-15, 09:17 PM
Nice shot of incandescent vapor trail: http://englishrussia.com/2013/02/14/breaking-tremendous-flash-in-the-skies-now/#more-121252

KaiYeves
2013-Feb-15, 09:22 PM
It's great that we have so much footage and other data, but I'm sorry the people got hurt. (At least they'll have a cool "scar story" to tell.)

eburacum45
2013-Feb-15, 09:54 PM
Nice shot of incandescent vapor trail: http://englishrussia.com/2013/02/14/breaking-tremendous-flash-in-the-skies-now/#more-121252

Fantastic! The vapour trail actually seems to be red hot! Can this be really the case?

publiusr
2013-Feb-15, 10:08 PM
Mark Boslough, a physicist at Sandia National Laboratories in New Mexico, is doing research on the body:
http://www.livescience.com/27184-russian-meteor-explosion-size-comparison.html
http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html

The wiki
http://en.wikipedia.org/wiki/2013_Russian_meteor_event

Press conference
http://www.jpl.nasa.gov/news/news.php?release=2013-062
http://www.spacedaily.com/reports/prnewswire-space-news.html?doc=201302151357PR_NEWS_USPR_____DC61265&showRelease=1&dir=0&categories=AEROSPACE-AND-SPACE-EXPLORATION&andorquestion=OR&&passDir=0,1,2,3,4,5,6,15,17,34
http://www.nature.com/news/russian-meteor-largest-in-a-century-1.12438
http://zyalt.livejournal.com/722930.html

Here one video shows the bolide seemingly heading for a driver:
http://www.cbc.ca/player/Embedded-Only/News/ID/2335365961/

More links:
http://www.rrobserver.com/news/local/article_13bbc210-5445-11e1-b7b3-0019bb2963f4.html
http://lunarmeteoritehunters.blogspot.com/2012/06/brasil-sandia-sentinel-allsky-camera.html
http://lunarmeteoritehunters.blogspot.com/2013/02/mbiq-detects-russia-fireball-meteor.html
http://www.space.com/19816-russian-meteor-earthquake-signal.html
http://www.space.com/19822-russian-fireball-biggest-explosion-century.html
http://www.space.com/19814-russia-meteor-explosion-fireball-season.html
http://www.space.com/19805-meteorite-crash-russia-injuries.html
http://forum.nasaspaceflight.com/index.php?topic=31118.0
http://www.spacedaily.com/reports/Meteor_shower_sows_panic_in_central_Russia_999.htm l
http://www.spacedaily.com/reports/The_end_of_the_world_Terror_over_Russian_meteor_99 9.html
http://www.universetoday.com/100003/russian-meteor-not-related-to-asteroid-flyby-nasa-confirms/

This event reminds me of Sikhote-Alin more than Tunguska:
http://en.wikipedia.org/wiki/Sikhote-Alin_meteorite

Misc:
http://adsabs.harvard.edu/full/1995pimo.conf...67K
http://www.ia.ucsb.edu/pa/display.aspx?pkey=2943


Rumor has it that data from the DMSP is not being shared as freely with folks like Tagliaferri as in the past. Infrasound may help pin things down.

O/T--At least Duncan Steele will get a good view of asteroid, 2012 DA14. He was the first to find an asteroid spinning so fast that it must be a monolith.
First photos of 2012 DA14: http://www.space.com/19825-asteroid-2012-da14-first-photos.html

Romanus
2013-Feb-15, 11:27 PM
Something I thought was very interesting was the heavy "contrail" from the meteor, which reminded me of a famous eyewitness painting of the Sikhote-Alin fall, by one Medvedev:

http://www.cometshopnew.com/paint.html

Every time I saw that picture I'd wonder what the deal with all the "smoke" was, knowing it was an iron meteorite fall--indeed, why there would be vapor of any kind associated with a meteorite as opposed to a jet engine or rocket. Even though I'm sure ablation has something to do with it, the brilliant and long-lived white trail following the object in the current footage is sobering and powerful support for the accuracy of the painting.

In any event, I can only echo the amazement of the footage and the rarity of something like this, and coincidentally during a record asteroid flyby, no less, while hoping that those injured come through all right and that the damage is swiftly repaired. This has got to set some kind of record for the amount of documentation for a single fall; wouldn't be surprised to see many papers come out of this. And, as others have said elsewhere, this could be an extremely potent wake-up call to the importance of finding and tracking PHAs, to say nothing of increasing funds for the agencies responsible.

Rhaedas
2013-Feb-15, 11:38 PM
It's evidence of how much damage can be done to populated areas, and this was one below the size we try to hunt for. Imagine a few sizes larger, or a comet of the same size, but a faster and more angled approach.

Xelebes
2013-Feb-16, 01:41 AM
That does not mean people are "hardy compared to structures". People are hardy compared to glass. Which should not be surprising.

BTW, Russian government already issued a statement that no "shooting down" was involved.

There were a couple buildings that collapsed, the most spectacular being the zinc factory in Chelyabinsk.

I heard Russian news reported one death. RIP, if this is confirmed.

Don Alexander
2013-Feb-16, 02:14 AM
The numbers are now 15 meters diameter, 7000 tons weight, and a 300 kiloton explosion.

And that on my birthday. :P

antoniseb
2013-Feb-16, 02:21 AM
That makes it a little bigger than the one over the Sudan a couple years ago.

Don Alexander
2013-Feb-16, 02:40 AM
Quite a lot bigger, I should say. after all, they're now claiming this has been the largest fall since Tunguska 1908.

Or, at the very least, the largest measured since the infrasound networks went up (1950s?) which are usually meant to monitor atmospheric nuclear explosions.

Solfe
2013-Feb-16, 03:07 AM
The numbers are now 15 meters diameter, 7000 tons weight, and a 300 kiloton explosion.

And that on my birthday. :P

Surprise! Happy Birthday!

Don Alexander
2013-Feb-16, 03:17 AM
Thanks! :D

It was very cosmic, with a decent GRB, a new bright SN, and asteroids large and small ;)

Ara Pacis
2013-Feb-16, 03:31 AM
Ya know what's weird. The Weather Channel has been airing some half hour documentaries on space weather that I have recorded over the last few weeks and I happened to watch one last night that was about meteor and asteroid impacts and I thought to myself that we were due for another one. I also watched an episode of "Doomsday Preppers" about a couple who are preparing for comet impact she believes she has dreamed and talked to a ghost about. Coincidence, you'd think. Well, two years ago I had recorded and watched some documentaries about tsunamis and the geology of the ring of fire and Japan and thought we were due for another one a few days before that big earthquake and tsunami near Sendai. Now, I don't/didn't consider these to be prognostications, but now I'm starting to wonder... if maybe I should stop watching documentaries about disasters.

Swift
2013-Feb-16, 03:33 AM
YouTube and other video sites are blocked at work, so I'm just watching the videos now and the sonic boom was particularly amazing and alarming.

Swift
2013-Feb-16, 03:34 AM
Thanks! :D

It was very cosmic, with a decent GRB, a new bright SN, and asteroids large and small ;)
I hope you blew out all these "candles".

Don Alexander
2013-Feb-16, 03:37 AM
It's a pity so far no audio recording of the booms has surfaced which is really capable of reproducing them in a way humans must have heard them.

(Well, you do need a goood sound system for that :P )

Ara Pacis
2013-Feb-16, 03:41 AM
YouTube and other video sites are blocked at work, so I'm just watching the videos now and the sonic boom was particularly amazing and alarming.

A scientist on CNN tried to describe how it works to a reporter who seemed baffled and dumbfounded, and I think he made the confusion worse by agreeing/suggesting that the damage was caused by sound. Though a sonic boom is similar, my understanding is that the damage is mostly caused by an explosive expansion of hot gases and only a little, if anything from kinetic atmospheric compression/displacement.

Xelebes
2013-Feb-16, 04:11 AM
A scientist on CNN tried to describe how it works to a reporter who seemed baffled and dumbfounded, and I think he made the confusion worse by agreeing/suggesting that the damage was caused by sound. Though a sonic boom is similar, my understanding is that the damage is mostly caused by an explosive expansion of hot gases and only a little, if anything from kinetic atmospheric compression/displacement.

Which would make a more appropriate to call it a thunder then. However, it ends up sounding like sonic booms.

Glom
2013-Feb-16, 04:40 AM
Some of those dash cam videos are amazing. Good thing there's such terrible driving on Russia's roads that cause so many drivers to have them.

TravisD
2013-Feb-16, 07:35 AM
I have to laugh at my title of this thread.

When I made this thread there were still just sparse reports on TV and they said it was "near Moscow." It obviously was some distance away.


About the boom in the videos. I had the great honor of being almost directly under the Sutter's Mill meteorite air burst which was 4-5 kilotons. It scared the hell out of me! I thought an airplane had crashed into my house. Obviously I dove for cover inside my own home. Considering how it knocked my pictures out of alignment I am actually amazed it didn't break any windows.

Kullat Nunu
2013-Feb-16, 10:48 AM
I have to laugh at my title of this thread.

When I made this thread there were still just sparse reports on TV and they said it was "near Moscow." It obviously was some distance away.

~1500 km, that is almost the distance between Los Angeles and Seattle! :D


About the boom in the videos. I had the great honor of being almost directly under the Sutter's Mill meteorite air burst which was 4-5 kilotons. It scared the hell out of me! I thought an airplane had crashed into my house. Obviously I dove for cover inside my own home. Considering how it knocked my pictures out of alignment I am actually amazed it didn't break any windows.

Latest estimates gives 500 kilotons for the explosion, a wee bit more than that one... ;)

Kullat Nunu
2013-Feb-16, 10:53 AM
Tunguska was 10-15 megatons, so we are talking about an explosion which is only one order of magnitude smaller... Wonder what could have happened if the Chelyabinsk meteor had much steeper entry angle.

Don Alexander
2013-Feb-16, 12:40 PM
Barringer Crater, that's what would've happened.

Okay, not that large, looks like the culprit behind Meteor Crater in Arizona was more the size of 2012 DA14, they estimate it at 10 Megatons.

antoniseb
2013-Feb-16, 01:02 PM
I have to laugh at my title of this thread.
When I made this thread there were still just sparse reports on TV and they said it was "near Moscow." ...

I also thought it was odd, so I changed the title from Moscow to Russia. Thanks for spurring us to slightly better accuracy!

Perikles
2013-Feb-16, 05:25 PM
The numbers are now 15 meters diameter, 7000 tons weight, and a 300 kiloton explosion.

And that on my birthday. :PAccording to this report (http://sociedad.elpais.com/sociedad/2013/02/16/actualidad/1361011929_907182.html)(in Spanish) it was 17 metres diameter and 10,000 tons mass :D. I'm a bit puzzled - assuming spherical, that gives about 2,500 cubic metres and a density of 4 tonnes per cubic metre. Is that expected? Rocks around here, and concrete, have a density of around 2.5

Rhaedas
2013-Feb-16, 05:30 PM
+5 points for the use of the word "mass".

How are they making these estimates anyway? Have they found any samples yet? It seems to me without knowing what kind of material it was made of, it's still a large range of what it could have been.

kucharek
2013-Feb-16, 05:43 PM
I have to laugh at my title of this thread.
When I made this thread there were still just sparse reports on TV and they said it was "near Moscow." It obviously was some distance away.

Russia is very large. That's why it is hit by meteorides so often... 1500km are no distance there and I think no Russian would complain about calling this "near Moscow" :)

Tog
2013-Feb-16, 06:24 PM
Here's a clip (http://www.youtube.com/watch?v=gQ6Pa5Pv_io&feature=youtu.be&t=4m20s) that shows the bolide and had the boom in one shot. It looks like a parked dashcam. Start it about 4:30 in and let it run til about 7:40. You can see the car shake multiple times from the different shocks.

Squink
2013-Feb-16, 06:31 PM
NOAA publishes EUMETSAT METEOSAT-10 satellite gif:
Meteorite Slams into Atmosphere Above Chelyabinsk, Russia (http://www.nnvl.noaa.gov/MediaDetail2.php?MediaID=1290&MediaTypeID=1)

publiusr
2013-Feb-16, 06:47 PM
Program tonight on Science Channel:
http://blogs.discovery.com/inscider/2013/02/russian-meteor-mayhem.html

Phil Plait's Bad Universe was on earlier today BTW.

The size has been increased--beyond the Teton event it looks:

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 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 meteor, which was about one-third the diameter of asteroid 2012 DA14, was brighter than the sun. Its trail was visible for about 30 seconds, so it was a grazing impact through the atmosphere.

http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html

Nice chart showing sizes
http://www.space.com/19829-russian-fireball-meteor-blast-infographic.html

Other fireballs!
San Francisco treat http://up-ship.com/blog/?p=18920
http://www.space.com/19836-meteor-california-bay-area.html

Both Cuba and Kazahkstan were hit too, it seems

Cuba strike http://up-ship.com/blog/?p=18909
http://www.tigerdroppings.com/rant/p/39966404/First-Russia-Then-Kazahkstan-Then-Cuba-DOOM-on-in-15-min-track-meteor-live.aspx
Kazahkstan
http://blogs.discovery.com/inscider/2013/02/russian-meteor-mayhem.html

More
http://www.space.com/19837-russia-fireball-asteroid-impact-surprise.html
http://www.space.com/19834-russian-meteor-crash-trail-and-trajectory-animated.html
http://www.space.com/19830-neos-near-earth-objects-the-video-show.html
http://www.space.com/19833-russia-meteor-asteroid-threat.html
http://www.space.com/19823-russia-meteor-explosion-complete-coverage.html
http://www.space.com/19646-asteroid-2012-da14-earth-flyby-complete-coverage.html
http://up-ship.com/blog/?p=18917
http://up-ship.com/blog/?p=18904

Updates:
http://www.spacedaily.com/reports/The_end_of_the_world_Terror_over_Russian_meteor_99 9.html
http://www.spacedaily.com/reports/Divers_scour_Russian_lake_after_meteor_strike_inju res_1200_999.html
http://www.spacedaily.com/reports/Stay_away_from_meteorites_government_tells_Russian s_999.html

Potential missions to NEOs
www.nasaspaceflight.com/2013/02/asteroid-highlights-investigate-neos-nasa-missions/
http://www.spacedaily.com/reports/Scientists_claim_discovery_of_Russian_meteorites_9 99.html
http://www.spacedaily.com/reports/Russia_halts_search_for_meteorite_in_stricken_regi on_999.html
http://www.spacedaily.com/reports/SciTechTalk_Earth_in_the_bullseye_999.html
http://www.spacedaily.com/reports/NASA_scrambles_for_better_asteroid_detection_999.h tml

eburacum45
2013-Feb-16, 07:54 PM
Both Cuba and Kazahkstan were hit too, it seems

Not Kazakstan; that was actually the same meteor seen in the distance. I've calculated roughly (from the separation of the timings of the flash and the bang on one of those youtube dashboard cam vids) that the explosion happened about 46 km above the city; something that high would be visible from hundreds of kilometers away.

The Cuba bolide was almost certainly just another random bright meteor; these happen every day somewhere i the world, and the few details available sound unremarkable.

peteshimmon
2013-Feb-16, 08:02 PM
Just read of an old aquaintance telling how
he was on local radio first thing yesterday
about the asteroid flyby and explaining that
big hits were very rare. Just an hour before
the hit! Sort of thing makes you think you
are being singled out:)

Anyway, nothing similar in my part of the
World please. Please..pretty please...

Squink
2013-Feb-16, 08:10 PM
the explosion happened about 46 km above the city; something that high would be visible from hundreds of kilometers away.
About 760 km (http://www.ringbell.co.uk/info/hdist.htm).

eburacum45
2013-Feb-16, 08:48 PM
Thanks; nice calculator!
The Kazakstan border is less than 200km away, so it should have been easily visible.

Hornblower
2013-Feb-16, 09:40 PM
A scientist on CNN tried to describe how it works to a reporter who seemed baffled and dumbfounded, and I think he made the confusion worse by agreeing/suggesting that the damage was caused by sound. Though a sonic boom is similar, my understanding is that the damage is mostly caused by an explosive expansion of hot gases and only a little, if anything from kinetic atmospheric compression/displacement.

As I see it, whether the cause of the atmospheric shock wave is explosive expansion of hot gases or displacement of the air by a supersonic solid body is beside the point for describing what reached the ground under the burst. Either way it was a pressure wave propagating through the air. This one was strong enough to smash a lot of windows and blow some doors open.

Hornblower
2013-Feb-16, 09:51 PM
Here's a clip (http://www.youtube.com/watch?v=gQ6Pa5Pv_io&feature=youtu.be&t=4m20s) that shows the bolide and had the boom in one shot. It looks like a parked dashcam. Start it about 4:30 in and let it run til about 7:40. You can see the car shake multiple times from the different shocks.

Good catch! Note that the main bang came about 140 seconds after the flareup, placing the burst about 30 miles from the car.

I think the crackling sound of the main bang was from overloading the microphone. I would expect a chest/gut-thumping BOOM like that of an aircraft sonic boom or a nearby cannon, only much more powerful.

Tog
2013-Feb-16, 09:55 PM
You can see the car shake when each one hits. The first one also looks like it does bad things to the building on the left. The other thing I like about that one is that you can see the flash out of frame AND in the reflection of the supercompact car's rear window.

eburacum45
2013-Feb-16, 10:02 PM
That's the same clip I used to estimate 46km as the height of the explosion; of course that doesn't allow for any sideways displacement, but it is my general impression from other clips that the airburst happened nearly overhead of the town.

Perikles
2013-Feb-17, 12:42 PM
I'm usually quite amused about how sometimes the UK considers itself to be the centre of the universe, but this article (http://www.guardian.co.uk/science/2013/feb/16/meteorite-uk)from the Guardian seems devoid of meaning:


The meteorite that caused devastation in the Urals on Friday could have struck Britain if it had entered the atmosphere at only a slightly different time of day, astronomers revealed yesterday.

True perhaps, but what is 'a slightly different time of day'? You might as well argue that it could have hit anywhere, or if only it had been bigger, or faster, or more massive. It could have hit New York with a 'slightly' different trajectory.

eburacum45
2013-Feb-17, 12:49 PM
If my grandma had wheels, she was a motorcycle.

KaiYeves
2013-Feb-17, 06:40 PM
I'm usually quite amused about how sometimes the UK considers itself to be the centre of the universe, but this article (http://www.guardian.co.uk/science/2013/feb/16/meteorite-uk)from the Guardian seems devoid of meaning:



True perhaps, but what is 'a slightly different time of day'? You might as well argue that it could have hit anywhere, or if only it had been bigger, or faster, or more massive. It could have hit New York with a 'slightly' different trajectory.
The Boston Globe featured an estimated damage radius if the meteor had come in over Boston, which I thought was a good way to help locals visualize the extent of the damage.

Rhaedas
2013-Feb-17, 07:53 PM
Great find, Tog. Seems like a lot more than three booms, based on the car's movement. An echo of the original wouldn't have the strength to do that, would it? My guess, and I could be wrong, is that we had an initial breakup, causing the first strong explosion and the forked trails, and then many smaller breakups from the fragments. After that point it likely lost enough speed for anything left to survive til ground impact.

Still too early to speculate on rock vs dirty iceball? Seems too slow for a new comet from the Oort cloud, but maybe an extinct one that's been around a while? Would a slow moving comet nucleus last as long as this one did?

eburacum45
2013-Feb-17, 09:17 PM
Here's another calculation; the mass of this object was about 10,000 tonnes, but it exploded with a force of 300 kilotons of TNT; that means that the explosive force caused by the kinetic energy of the meteor was at least thirty times as powerful as its chemical energy, even if it were made of TNT.

publiusr
2013-Feb-17, 09:32 PM
Potential missions to NEOs
www.nasaspaceflight.com/2013/02/asteroid-highlights-investigate-neos-nasa-missions/

Ed Lu on CNN
http://whatsnext.blogs.cnn.com/2013/02/15/a-chance-to-prevent-future-asteroid-impacts/
From Meet The Press
www.space.com/19844-russia-meteor-former-astronaut-says-universe-is-a-crowded-place.html


I wonder if something like this could bag a spaceberg in a foldable biconic aeroshell http://whatsnext.blogs.cnn.com/2013/01/31/the-origami-inspired-folding-kayak/?iref=obinsite

UN having a look:
www.space.com/19840-asteroid-impact-threat-united-nations.html http://forum.nasaspaceflight.com/index.php?topic=31118.315

Last nights Science Channel special was really nice. A lot of simulations from Sandia, like these
https://share.sandia.gov/news/resources/releases/2007/asteroid.html

Ara Pacis
2013-Feb-18, 06:51 AM
As I see it, whether the cause of the atmospheric shock wave is explosive expansion of hot gases or displacement of the air by a supersonic solid body is beside the point for describing what reached the ground under the burst. Either way it was a pressure wave propagating through the air. This one was strong enough to smash a lot of windows and blow some doors open.

Right. My point was that the science guy was calling them sound waves, an the anchor was incredulous, for obvious reason.

Hornblower
2013-Feb-18, 12:31 PM
Right. My point was that the science guy was calling them sound waves, an the anchor was incredulous, for obvious reason.

The reasons are not at all obvious without a playback of the conversation or a verbatim playback thereof.

NEOWatcher
2013-Feb-18, 03:01 PM
True perhaps, but what is 'a slightly different time of day'? You might as well argue that it could have hit anywhere, or if only it had been bigger, or faster, or more massive. It could have hit New York with a 'slightly' different trajectory.
And the Earth would have been somewhere else too.
(Same as my comment about Tunguska in this earlier post (http://cosmoquest.org/forum/showthread.php/142173-Meteor-falls-over-Russia?p=2108344#post2108344))

Squink
2013-Feb-18, 03:26 PM
Space Rock Fragments In Russian Lake (http://news.sky.com/story/1053619/meteor-space-rock-fragments-in-russian-lake)
Viktor Grokhovsky, a member of the Russian Academy of Sciences, told the RIA Novosti news agency:...

"This meteorite belongs to the class of regular chondrites," a university statement said.

"Most likely, the find will be called Meteorite Chebarkul."

Ara Pacis
2013-Feb-18, 03:39 PM
A question for y'all. How confident are we that these types of asteroid/meteor impacts are only about 1 in 100 years? How well can we detect them over oceans? And assuming we can detect them (infrasound, sonar and siesmology maybe), how long have we had that capability? Or is the frequency only based on size and distribution assumptions of the populations of such objects in the solar system.

Cougar
2013-Feb-18, 04:47 PM
Or is the frequency only based on size and distribution assumptions of the populations of such objects in the solar system.

Well, the size distribution isn't an assumption. The moon is a pretty good recording 'device' showing that collision sizes obey a power law. In other words, lots and lots of small ones, fewer medium ones, and very few large ones, with everything in between on an exponential scale from large to small. Converting that to "once every x years," oh, I'm sure there's then some clever way astrofolk do that....

Rhaedas
2013-Feb-18, 06:44 PM
I heard on the radio they've been finding small "pebbles" around the town's location, as well as near the impact sites.

Ara Pacis
2013-Feb-19, 06:31 AM
Well, the size distribution isn't an assumption. The moon is a pretty good recording 'device' showing that collision sizes obey a power law. In other words, lots and lots of small ones, fewer medium ones, and very few large ones, with everything in between on an exponential scale from large to small. Converting that to "once every x years," oh, I'm sure there's then some clever way astrofolk do that....

Do it require maffs?

kzb
2013-Feb-19, 06:18 PM
They are now saying this object was 17 metres across and weighed 10,000 tonnes. The explosive force revised up to 500kT equivalent (i.e half a megaton).

This new diameter is about half that of 2012 DA14. That means the meteor has about one-quarter the projected area of the asteroid. I'm guessing, as an order of magnitude thing, that its apparent brightness at equal distance would be about one-quarter also. (OK maybe a bit less, because it is somewhat less than half the radius.)

Question: how come 2012 DA14 was tracked so well, but they were apparently blind-sided by this object?

NEOWatcher
2013-Feb-19, 06:39 PM
This new diameter is about half that of 2012 DA14. That means the meteor has about one-quarter the projected area of the asteroid. I'm guessing, as an order of magnitude thing, that its apparent brightness at equal distance would be about one-quarter also. (OK maybe a bit less, because it is somewhat less than half the radius.)
To be more precise... 17m:45m, or 7 times larger cross section.


Question: how come 2012 DA14 was tracked so well, but they were apparently blind-sided by this object?
Good question... I heard it was because of the direction it came from.
But; I'm sure things like size, albedo and even what astronomers are focusing on are also contributing factors.

Perikles
2013-Feb-19, 07:53 PM
They are now saying this object was 17 metres across and weighed 10,000 tonnes. They were saying that when I posted no. 49 three days ago.

StupendousMan
2013-Feb-19, 08:50 PM
A question for y'all. How confident are we that these types of asteroid/meteor impacts are only about 1 in 100 years?

Read "The rate of small impacts on Earth", link below.

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=2006M%26PS...41..607B&db_key=AST

Rhaedas
2013-Feb-19, 09:18 PM
Question: how come 2012 DA14 was tracked so well, but they were apparently blind-sided by this object?

Because we found 2012 DA14 last year and had enough data to follow and calculate its orbit. There have been plenty of asteroids we've only seen after the close pass. It's a big sky, and not being able to observe during the day is part of the problem. That's a good 50% that can't be observed by ground based telescopes, and if something is coming from that direction, we are blind.

TravisD
2013-Feb-19, 09:57 PM
To be more precise... 17m:45m, or 7 times larger cross section.


Good question... I heard it was because of the direction it came from.
But; I'm sure things like size, albedo and even what astronomers are focusing on are also contributing factors.


Because we found 2012 DA14 last year and had enough data to follow and calculate its orbit. There have been plenty of asteroids we've only seen after the close pass. It's a big sky, and not being able to observe during the day is part of the problem. That's a good 50% that can't be observed by ground based telescopes, and if something is coming from that direction, we are blind.

The conspiracy theory crowd are going nuts over the fact that this wasn't spotted in time. They seem to especially think it odd that we have so many satellites in orbit and none of them spotted it. They are, of course, ignoring that the vast, vast majority of those satellites have no capability to spot an asteroid and are pointed at earth!

Swift
2013-Feb-19, 10:06 PM
The conspiracy theory crowd are going nuts over the fact that this wasn't spotted in time. They seem to especially think it odd that we have so many satellites in orbit and none of them spotted it. They are, of course, ignoring that the vast, vast majority of those satellites have no capability to spot an asteroid and are pointed at earth!
Yeah, if I can get HBO, why can't they stop a meteor from hitting Russia! :scope:

theville24
2013-Feb-20, 07:30 AM
That was extraordinary!! Although it wasn't as big as the 1908 meteor, but still an exciting astronomical event!

TravisD
2013-Feb-20, 07:55 AM
I'm waiting for them to ask why Hubble didn't spot it.

Jens
2013-Feb-20, 09:02 AM
I'm waiting for them to ask why Hubble didn't spot it.

What, we sent the Voyagers to the edge of the heliosphere, and they can't even spot an incoming meteor? :)

kzb
2013-Feb-20, 01:00 PM
They were saying that when I posted no. 49 three days ago.

Yeh you did. You also save me from asking my question on the apparent high density (3.9g/cm^3) which you have already noted.

Perikles
2013-Feb-20, 01:18 PM
Yeh you did. You also save me from asking my question on the apparent high density (3.9g/cm^3) which you have already noted...... which nobody has responded to, making me think that my post was perhaps invisible.

glappkaeft
2013-Feb-20, 03:41 PM
From wikipedia: (http://en.wikipedia.org/wiki/Standard_asteroid_physical_characteristics#Density )

"A recent paper gives calculations for the mean densities of C, S, and M class asteroids as 1.38, 2.71, and 5.32 g/cm3"

Squink
2013-Feb-21, 02:26 AM
Anti-Monopoly Watchdog to Monitor Glass Prices in Chelyabinsk (http://www.themoscowtimes.com/news/article/anti-monopoly-watchdog-to-monitor-glass-prices-in-chelyabinsk/475829.html)
Chelyabinsk Governor Mikhail Yurevich said Monday there was no deficit of window glass in the region thanks to timely shipments from neighboring areas. He noted that window glass had already been replaced in 53 percent of the windows with undamaged frames, RIA-Novosti said. http://www.wunderground.com/cgi-bin/findweather/getForecast?query=Chelyabinsk%2C+ru

Bad Ronald
2013-Feb-21, 07:06 PM
I hope this was a wake-up call to TPTB about threats from above.

publiusr
2013-Feb-22, 10:14 PM
The military needs to open up
www.space.com/19846-russian-meteor-fallout-military-satellites.html

Deflection
http://up-ship.com/blog/?p=18971

The usual suspects think it was a shootdown :)
http://www.coasttocoastam.com/show/2013/02/15
http://www.youtube.com/watch?v=u_OxMaJPiC8
http://www.godlikeproductions.com/forum1/message2145738/pg1

Don Alexander
2013-Feb-23, 01:23 AM
*follows some of those links*

Now my brain hurts. :(

KaiYeves
2013-Feb-23, 01:42 AM
If it makes you feel any better, the joke "theory" I shared at Astronomy Club on Wednesday was that the cause of the impact was Aaron Sorkin, because a papal resignation, a nuclear test, a State of the Union Address and a meteorite fall on the same day as an unrelated asteroid flyby all happening in one week sounds so much like the plot of a West Wing episode.

Don Alexander
2013-Feb-23, 02:33 PM
CBET 3423, just published:

TRAJECTORY AND ORBIT OF THE CHELYABINSK SUPERBOLIDE
Jiri Borovicka, Pavel Spurny, and Lukas Shrbeny, Astronomical Institute of the Academy of Sciences, Ondrejov, Czech Republic, report that they have computed the atmospheric trajectory and velocity of the superbolide of 2013 Feb. 15.139 UT (3h20m UT), which caused some damage in the city of Chelyabinsk, Russia. They used seven casual video records provisionally calibrated with Google Maps tools. The trajectory was assumed to be linear. The geographical coordinates of selected points along the trajectory are as tabulated below:

Relative Longitude Latitude Height Velocity Notes
Time (s) (deg E) (deg N) (km) (km/s)

0.00 64.266 54.508 91.83 17.5 beginning of registration
9.18 61.913 54.788 41.02 17.5 minor flare
11.20 61.455 54.836 31.73 17.5 major flare
12.36 61.159 54.867 25.81 17.5 flare
13.20 60.920 54.891 21.05 12.5 minor flare
16.20 60.606 54.922 14.94 4.3 end of registration

The observed trajectory was 254 km long. The azimuth of the trajectory was 279.5 degrees, and the slope was 16.5 degrees to the horizontal (for the end point). The uncertainty of the radiant is about one degree. The uncertainty of the position of the trajectory is about 1 km (at the beginning, up to 4 km). The pre-entry object that caused the superbolide was relatively fragile. Severe fragmentation started at a height of 32 km under dynamic pressure of 4 MPa. The mass of the largest fragment, which landed in the lake Chebarkul, was estimated to be 200-500 kg. One or two meteorites of the mass of several tens of kg can be expected not far from the village Travniki. One piece of mass approximately 1 kg may have landed to the northwest of Shchapino. Numerous small fragments can be expected in the wide band located about 5 km south of the trajectory, mostly between longitudes 60.9 and 61.35 degrees. The blast wave, which strongly affected Chelyabinsk, was generated between heights of 25 and 30 km. The radiant and heliocentric orbit were calculated to be as follows:

Apparent radiant: Right ascension 328.6 +/- 1.0 deg
(equinox 2000.0) Declination +8.0 +/- 1.0 deg
Velocity 17.5 +/- 0.5 km/s

Geocentric radiant: Right ascension 334.7 +/- 1.2 deg
Declination -1.0 +/- 1.4 deg
Velocity 13.2 +/- 0.7 km/s

Orbit: a = 1.55 +/- 0.07 AU e = 0.50 +/- 0.02
q = 0.768 +/- 0.011 AU Q = 2.33 +/- 0.14 AU
(equinox 2000.0) Peri. = 109.7 +/- 1.8 deg Node = 326.41 deg
i = 3.6 +/- 0.7 deg

The data do not allow determination of the initial mass of the object prior to entering the atmosphere. The trajectory will be further refined in the future, provided that proper in situ calibrations of the videos are made.

Hornblower
2013-Feb-23, 05:14 PM
CBET 3423, just published:

TRAJECTORY AND ORBIT OF THE CHELYABINSK SUPERBOLIDE
Jiri Borovicka, Pavel Spurny, and Lukas Shrbeny, Astronomical Institute of the Academy of Sciences, Ondrejov, Czech Republic, report that they have computed the atmospheric trajectory and velocity of the superbolide of 2013 Feb. 15.139 UT (3h20m UT), which caused some damage in the city of Chelyabinsk, Russia. They used seven casual video records provisionally calibrated with Google Maps tools. The trajectory was assumed to be linear. The geographical coordinates of selected points along the trajectory are as tabulated below:

Relative Longitude Latitude Height Velocity Notes
Time (s) (deg E) (deg N) (km) (km/s)

0.00 64.266 54.508 91.83 17.5 beginning of registration
9.18 61.913 54.788 41.02 17.5 minor flare
11.20 61.455 54.836 31.73 17.5 major flare
12.36 61.159 54.867 25.81 17.5 flare
13.20 60.920 54.891 21.05 12.5 minor flare
16.20 60.606 54.922 14.94 4.3 end of registration

The observed trajectory was 254 km long. The azimuth of the trajectory was 279.5 degrees, and the slope was 16.5 degrees to the horizontal (for the end point). The uncertainty of the radiant is about one degree. The uncertainty of the position of the trajectory is about 1 km (at the beginning, up to 4 km). The pre-entry object that caused the superbolide was relatively fragile. Severe fragmentation started at a height of 32 km under dynamic pressure of 4
MPa. The mass of the largest fragment, which landed in the lake Chebarkul, was estimated to be 200-500 kg. One or two meteorites of the mass of several tens of kg can be expected not far from the village Travniki. One piece of
mass approximately 1 kg may have landed to the northwest of Shchapino. Numerous small fragments can be expected in the wide band located about 5 km south of the trajectory, mostly between longitudes 60.9 and 61.35 degrees.
The blast wave, which strongly affected Chelyabinsk, was generated between heights of 25 and 30 km. The radiant and heliocentric orbit were calculated to be as follows:

Apparent radiant: Right ascension 328.6 +/- 1.0 deg
(equinox 2000.0) Declination +8.0 +/- 1.0 deg
Velocity 17.5 +/- 0.5 km/s

Geocentric radiant: Right ascension 334.7 +/- 1.2 deg
Declination -1.0 +/- 1.4 deg
Velocity 13.2 +/- 0.7 km/s
Orbit: a = 1.55 +/- 0.07 AU e = 0.50 +/- 0.02
q = 0.768 +/- 0.011 AU Q = 2.33 +/- 0.14 AU
(equinox 2000.0) Peri. = 109.7 +/- 1.8 deg Node = 326.41 deg
i = 3.6 +/- 0.7 deg

The data do not allow determination of the initial mass of the object prior to entering the atmosphere. The trajectory will be further refined in the future, provided that proper in situ calibrations of the videos are made.

My bold. If I interpret that geocentric radiant correctly, that means the object was coming in about 15 degrees from the Sun, showing a very thin crescent phase. Assuming an albedo similar to that of the Moon, I get a rough magnitude estimate of about 20 when it was at the Moon's distance, several hours out. In other words, a very faint telescopic object, lost in twilight glare. No wonder it was not seen on the way in.

publiusr
2013-Feb-23, 06:34 PM
Here are some other stories from around the internet:

http://www.americaspace.com/?p=31501
http://www.space.com/19933-asteroid-deflection-mission-aida-didymos.html
http://www.space.com/19905-dangerous-asteroid-deflection-paint.html
http://bigthink.com/ideafeed/finding-killer-space-rocks-before-they-find-us-turbo-edition
http://io9.com/5986280/was-chelyabinsk-meteor-actually-a-meteor-many-russians-remain-unconvinced
http://io9.com/5985169/who-should-be-in-charge-of-defending-earth-against-asteroids?tag=space
http://io9.com/5984951/how-to-collect-meteorites-in-your-backyard?tag=space
http://io9.com/5984861/russias-meteor-explosion-was-heard-half+way-around-the-world?tag=space
http://io9.com/5985185/here-is-a-map-that-shows-every-meteorite-that-has-hit-earth-since-2300-bc?tag=space
http://io9.com/5985276/incredible-details-are-emerging-about-russias-chelyabinsk-meteor?tag=space
http://bigthink.com/experts-corner/da14-a-wake-up-call-from-space
http://bigthink.com/think-tank/make-room-in-the-budget-for-big-audacious-ideas
http://www.thespacereview.com/article/2243/1
http://www.space.com/19910-meteor-fireball-astronomy-mystery.html
http://www.space.com/19912-russian-meteor-video-record.html
http://www.space.com/19864-asteroid-threat-atlas-warning-system.html
http://www.space.com/12282-7-strangest-asteroids-solar-system-space-rocks.html
http://www.spacedaily.com/reports/The_Asteroids_are_Coming_999.html
http://www.spacedaily.com/reports/Russian_Fireball_Largest_Ever_Detected_by_CTBTOs_I nfrasound_Sensors_999.html
http://www.spacedaily.com/reports/Asteroid_Steins_hidden_gems_999.html

Swift
2013-Feb-23, 07:59 PM
Here are some other stories from around the internet:

http://www.americaspace.com/?p=31501
http://www.space.com/19933-asteroid-deflection-mission-aida-didymos.html
http://www.space.com/19905-dangerous-asteroid-deflection-paint.html
http://bigthink.com/ideafeed/finding-killer-space-rocks-before-they-find-us-turbo-edition
http://io9.com/5986280/was-chelyabinsk-meteor-actually-a-meteor-many-russians-remain-unconvinced
http://io9.com/5985169/who-should-be-in-charge-of-defending-earth-against-asteroids?tag=space
http://io9.com/5984951/how-to-collect-meteorites-in-your-backyard?tag=space
http://io9.com/5984861/russias-meteor-explosion-was-heard-half+way-around-the-world?tag=space
http://io9.com/5985185/here-is-a-map-that-shows-every-meteorite-that-has-hit-earth-since-2300-bc?tag=space
http://io9.com/5985276/incredible-details-are-emerging-about-russias-chelyabinsk-meteor?tag=space
http://bigthink.com/experts-corner/da14-a-wake-up-call-from-space
http://bigthink.com/think-tank/make-room-in-the-budget-for-big-audacious-ideas
http://www.thespacereview.com/article/2243/1
http://www.space.com/19910-meteor-fireball-astronomy-mystery.html
http://www.space.com/19912-russian-meteor-video-record.html
http://www.space.com/19864-asteroid-threat-atlas-warning-system.html
http://www.space.com/12282-7-strangest-asteroids-solar-system-space-rocks.html
http://www.spacedaily.com/reports/The_Asteroids_are_Coming_999.html
http://www.spacedaily.com/reports/Russian_Fireball_Largest_Ever_Detected_by_CTBTOs_I nfrasound_Sensors_999.html
http://www.spacedaily.com/reports/Asteroid_Steins_hidden_gems_999.html
No, that is just out of control. You have been warned about these link farms before - this is completely unacceptable.

Cougar
2013-Feb-26, 08:23 PM
NASA explains What Exploded Over Russia? (http://www.youtube.com/watch?v=-qZ6oiaSm00)

Swift
2013-Mar-01, 09:22 PM
From CNN.com (http://edition.cnn.com/2013/02/27/world/europe/russia-meteor/)

The meteor that exploded over the steppes of southwestern Russia sent a low-frequency rumble bouncing through the Earth, giving scientists new clues about the biggest cosmic intruder in a century.

The big boom over Chelyabinsk on February 15 also produced a wave of sound thousands of times lower than a piano's middle C -- far below the range of human hearing, according to the international agency that watches for nuclear bomb tests. The Comprehensive Test Ban Treaty Organization said that sound wave showed up on sensors from Greenland to Antarctica, making it the largest ever detected by its network.

Scientists then used that wave to calculate the size of the small asteroid that plunged to Earth, said Margaret Campbell-Brown, an astronomer at Canada's University of Western Ontario.

The duration of the wave -- about 32 seconds -- let scientists estimate the energy of the blast at between 450 and 500 kilotons, the size of about 30 early nuclear bombs

TooMany
2013-Mar-01, 11:06 PM
The strangest thing about this is the coincidence with the near miss by 2012 DA14, which was on an entirely different orbit. You have two very rare events happening almost simultaneously.

I guess coincidences do happen.

Another coincidence, if you will, is the grazing trajectory of this meteor (16.5 degrees from horizontal) which means it nearly missed our big orb. Perhaps it would have missed if not for earth's gravity since it was moving at only 2.3 times low orbital speed. I suppose a much steeper angle would have resulted in a large crater. Anyone know how big?

Chew
2013-Mar-01, 11:32 PM
The strangest thing about this is the coincidence with the near miss by 2012 DA14, which was on an entirely different orbit. You have two very rare events happening almost simultaneously.

I guess coincidences do happen.

Another coincidence, if you will, is the grazing trajectory of this meteor (16.5 degrees from horizontal) which means it nearly missed our big orb. Perhaps it would have missed if not for earth's gravity since it was moving at only 2.3 times low orbital speed. I suppose a much steeper angle would have resulted in a large crater. Anyone know how big?

Playing around with the Earth Impact Effects Program (http://impact.ese.ic.ac.uk/ImpactEffects/) would seem to indicate an object this small will never reach the surface intact.

Nicolas
2013-Mar-02, 02:10 PM
I'm a bit confused here. Some sources say the damage was done by the explosion gasses, other by the sonic booms of the object entering the atmosphere, others by the (sonic) booms caused by the explosion...what is right, what is wrong and what is a matter of potato/potahto?

neilzero
2013-Mar-02, 04:02 PM
Yes, potato, patahto, but explosion gases is a stretch. Sonic boom is usually reserved for sound produced by large objects traveling faster than the speed of sound, the sound of an explosion is a close relative to a sonic boom. Likely few windows would have broken without the explosion. A very dry stony or iron meteor, that size would likely hit the ground. The explosions are thought to be steam pressure explosions so no volitiles = explosion unlikely. Neil

TooMany
2013-Mar-02, 06:37 PM
Playing around with the Earth Impact Effects Program (http://impact.ese.ic.ac.uk/ImpactEffects/) would seem to indicate an object this small will never reach the surface intact.

That's what it says all right, no crater. It's rather surprising because the meteor's path through the atmosphere was 245 kilometers long. If it had come straight down, at least some big fragments would strike earth.

Anyhow, it's an interesting lesson in how much protection we get from the atmosphere. Unless the meteor is large enough, it will largely self-destruct. This one at 50,000 ft (if it came straight down). That leaves a lot of atmosphere to slow down the remains.

Don Alexander
2013-Mar-02, 11:14 PM
http://neo.jpl.nasa.gov/news/fireball_130301.html

Here's some recent info from NASA. It's "grown" a bit (18 meters), but the explosion energy has decreased slightly (440 kT).

"U.S. government sensors". I guess that means satellites looking for ICBM launches...

And it came pretty much straight out of the Sun. (Well, not literally...)

Squink
2013-Mar-07, 06:25 PM
Sky & Telescope: Update on Russia's Mega-Meteor (http://www.skyandtelescope.com/news/home/Update-on-the-Russian-Mega-Meteor-195553631.html)
the point of peak brightness, which occurred (according to NASA dynamicists) at an altitude of 14.5 miles (23.3 km).

ASTRO BOY
2013-Mar-09, 01:11 AM
We need to be alert but at this stage but not alarmed.
Afterall what good would that do us?


Another article on the subject is as follows......





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Russian asteroid explosion and past impactors paint a potentially grim future for Earth March 8, 2013 by Dan Majaess, Universe Today


The recent meteor explosion over Chelyabinsk brought to the forefront a topic that has worried astronomers for years, namely that an impactor from space could cause widespread human fatalities. Indeed, the thousand+ injured recently in Russia was a wake-up call. Should humanity be worried about impactors? "Hell yes!" replied astronomer Neil deGrasse Tyson to CNN's F. Zakharia .


more at....

http://phys.org/news/2013-03-russian-asteroid-explosion-impactors-potentially.html

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Ara Pacis
2013-Mar-09, 09:11 PM
I'm more worried about what it might mean for space habitats. If we have structures in space with a large mass and cross-section, then we might need to stop worrying about micro-meteoroids and look at macro-meteoroids if we're gonna have problems seeing them in advance and/or have problems moving such structures to avoid impact.

neilzero
2013-Mar-09, 09:36 PM
If we have lots of large structures scattered about the inner solar system we can have lots of platforms to catch the surprise impactors, and get their orbits charted more perfectly. Reasonably most of these structures will have some ability to change their orbit when threatened. Neil

Ara Pacis
2013-Mar-10, 01:19 AM
If we have lots of large structures scattered about the inner solar system we can have lots of platforms to catch the surprise impactors, and get their orbits charted more perfectly. Reasonably most of these structures will have some ability to change their orbit when threatened. Neil

There's a path to take from the persent to that postulated future wherein the "lots of structures scattered around the inner solar system...to catch the surprise impactors" doesn't exist. And how reasonable is it to assume that large structures will have some ability to change their orbit in a timely manner? Something the size of a Stanford Torus or an O'Neil Cylinder may not be able to react quickly enough with a short detection leadtime.

NEOWatcher
2013-Mar-11, 04:34 PM
Something the size of a Stanford Torus or an O'Neil Cylinder may not be able to react quickly enough with a short detection leadtime.
True; but aren't we getting way ahead of ourselves?
By the time we get to that point, the risks will be easier to determine and mitigate. In addition, the construction may take this into account.

Anything that we can feasibly build now has such a small cross section as to give the risk almost a nil value.

Ara Pacis
2013-Mar-12, 04:59 AM
True; but aren't we getting way ahead of ourselves?
By the time we get to that point, the risks will be easier to determine and mitigate. In addition, the construction may take this into account.

Anything that we can feasibly build now has such a small cross section as to give the risk almost a nil value.

Srsly? Were the participants of the NASA Summer Study at Stanford getting ahead of themselves when they came up with those designs 38 years ago hoping they'd be implemented by now?

It's not clear how easy it will be to detect or mitigate. This one snuck up on us and came out of the sun. If we want to spot it optically, then we'd need to have viewpoints that provide different angles. And we'd need to spread sensors out along the planetary orbit to spot the things that may not come close enough to the planet normally to be detected. Or we might use powerful search radars, but there may be issues with that. Mitigation will depend on time to impact which will depend on detection range.

How would the construction take this into account? I doubt anything we can realistically build would be able to handle an impact from a 15 meter asteroid/Chelyabinsk-level impact. I wonder what would be the maximum size NEO that might be absorbed by a shield. Is 1 m still too big? The question is whether we could move the station and/or deflect the potential impactor within the time of detection.

NEOWatcher
2013-Mar-12, 05:23 PM
Srsly? Were the participants of the NASA Summer Study at Stanford getting ahead of themselves when they came up with those designs 38 years ago hoping they'd be implemented by now?
Were they? Absolutely, and they even said that (http://settlement.arc.nasa.gov/75SummerStudy/Foreword1.html):

The study summarized in this volume is another mind-stretcher. As explained on the following page, settlement in space is not an authorized program, and no man can now say if or when such a dazzling venture may be formally undertaken.


I'm not saying the risk isn't there. I'm saying that working with risk of today's technology can't be complicated with something that is nothing more than just a dream. Let's concentrate off the chunks that we can handle for now and in the near future.

Ara Pacis
2013-Mar-12, 06:55 PM
Were they? Absolutely, and they even said that (http://settlement.arc.nasa.gov/75SummerStudy/Foreword1.html):



I'm not saying the risk isn't there. I'm saying that working with risk of today's technology can't be complicated with something that is nothing more than just a dream. Let's concentrate off the chunks that we can handle for now and in the near future.

Speak for yourself. We have the technology, only the will is lacking, and that can change on a dime.

NEOWatcher
2013-Mar-13, 08:03 PM
Speak for yourself. We have the technology, only the will is lacking, and that can change on a dime.
By will, I assume you mean the will to spend tons of money on the project.
Yes; I speak for myself, but that's a pretty big dime to turn on.

Ara Pacis
2013-Mar-14, 06:51 AM
By will, I assume you mean the will to spend tons of money on the project.
Yes; I speak for myself, but that's a pretty big dime to turn on.

It's happened before in the US, Moon Program, post 9/11, post Pearl Harbor...

NEOWatcher
2013-Mar-14, 11:50 AM
It's happened before in the US, Moon Program, post 9/11, post Pearl Harbor...
Those seem very small scale compared to building such a large ship. Besides, I don't see where the politics of building something like that can spark the call of the people when compared to those examples you gave.
Am I wrong? I wouldn't rule it out. But it seem far-fetched enough to me to think that we should start with mitigation plans for the foreseable circumstances. Things like that come later. And that has been the main point I have been trying to make all along.

neilzero
2013-Mar-14, 12:30 PM
I have given some thought to radar detection of objects at several AU. If we can transmit a billion consectitive but different pulses and pulse bursts per hour from many widely separated transmitters (thoughout the inner solar system a significant number of the pulses will be received by many widely scattered receivers that were reflected off objects up to 1/2 light hour from a transmitter. Synchronizing the net work and analyzing the data may be possible. Only pulses reflected by objects more than 1/2 light hour will have multiple solutions, but typically these will be too weak to detect at all. It appears we can get a once per hour up date as far away as the Kupier belt, but the cost would be huge? The system would also provide the equivelent of GPS thoughout the inner solar system and very slow even farther out, and spotty. Neil

antoniseb
2013-Mar-14, 12:38 PM
I have given some thought to radar detection of objects at several AU. ...
It could act (for better or worse) like a fairly bright "Look At Me" signal to any nearby ETs.

Ara Pacis
2013-Mar-15, 12:10 AM
It could act (for better or worse) like a fairly bright "Look At Me" signal to any nearby ETs.

Yup.


Those seem very small scale compared to building such a large ship. Besides, I don't see where the politics of building something like that can spark the call of the people when compared to those examples you gave.

In goal, in magnitude, in fixed cost or in relative cost?


Am I wrong? I wouldn't rule it out. But it seem far-fetched enough to me to think that we should start with mitigation plans for the foreseable circumstances. Things like that come later. And that has been the main point I have been trying to make all along. Do you go leave the house and for a walk without first checking what the weather is like and dressing appropriately?

NEOWatcher
2013-Mar-15, 01:12 PM
Do you go leave the house and for a walk without first checking what the weather is like and dressing appropriately?
You seem to be completely missing my point.
Using your analogy, I would leave the house for a walk without checking the almanac to see what the weather will be next year.

KaiYeves
2013-Mar-15, 03:24 PM
I saw a feature saying that the meteor fall was the fastest "video event" to reach 100 million views, but I'm not sure how they were counting, because there seem to be about a thousand different videos of the event...

neilzero
2013-Mar-15, 04:40 PM
It could act (for better or worse) like a fairly bright "Look At Me" signal to any nearby ETs.

I may be wrong, but I think unique pulse bursts look like noise to SETI but it could increase the power by several times on some frequencies, as only a small portion of the radio frequencies Earth produces escape beyond the Van Allen belts, plus much of what escapes is distorted. Perhaps radar will rarely be used in space as it is one of our brightest "look at me" signals. As we move applications to higher frequencies, I suppose Earth is getting brighter, since these escape more readilly, but this is offset some by more directional transmitting antennas. Neil

Ara Pacis
2013-Mar-15, 11:09 PM
You seem to be completely missing my point.
Using your analogy, I would leave the house for a walk without checking the almanac to see what the weather will be next year.If you're going for a year long walk...

NEOWatcher
2013-Mar-18, 03:31 PM
If you're going for a year long walk...
Exactly my point. I don't see myself taking that long walk. If I did plan on doing that, then (and only then) would I worry about provisions for that walk. If I'm not ready to allow for those provisions, I don't take that walk.
Taking an umbrella, snow boots, a parka, and whatever else for a short walk just in case it turns into a long walk just isn't productive. (Although; it would give me a heck of a workout)