Author Topic: Meteor Strikes Chelyabinsk, Russia  (Read 136604 times)

Offline kevin-rf

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #420 on: 02/21/2013 03:06 PM »
You couldn't want to blast and create a debris field.

The advantage of cracking an incoming meteor is the smaller the bits, the higher up the bits breakup. Chelyabinsk was ~500 kt at ~30km, if it had been 500 kt at a couple of km the outcome would have been much more tragic. You still will have the same amount of energy released, it just be at a higher altitude. An end game that attempts to crack them just before entry could save lives from the 10m plus objects.
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Offline douglas100

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #421 on: 02/21/2013 03:31 PM »

If its so large a rock in space it will destroy all life on earth that's one matter.

This planet has been bombarded by objects of different sizes for billions of years. Life is still here. Humans, that's a different matter...
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Online Robotbeat

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #422 on: 02/21/2013 05:03 PM »

If its so large a rock in space it will destroy all life on earth that's one matter.

This planet has been bombarded by objects of different sizes for billions of years. Life is still here. Humans, that's a different matter...
Not entirely true, actually. I'm actually not entirely sure life would've survived the impact that created the Moon. On Earth itself, everything would be high enough temperature to be sterilized. Life would've only survived by being blown out into space, but then that's not "life on Earth" any longer.
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Offline douglas100

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #423 on: 02/21/2013 11:02 PM »

Not entirely true, actually.

What's not entirely true? I said that life is still here. I think you'll find that is entirely true.  :)

The other point, that the impact of a Moon sized object could sterilize the Earth is probably true. But it obviously hasn't happened since life has arisen on this planet. The chance of that happening before the Sun becomes hot enough to destroy life on Earth is very small indeed. (There is apparently a few percent chance that the orbits of Mars or Mercury could become chaotic enough in four or five billions years time to cause planetary collisions.)

We don't have to worry about collisions of that magnitude. Impacts of objects the size of the Chelyabinsk meteor and up to kilometers in scale, we do, of course, have to worry about.
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Offline Comga

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #424 on: 02/21/2013 11:04 PM »
Or, how about a counter-orbiting impactor, giving a relative velocity of 60km/s, far beyond chemical explosives. Could be accelerated slowly using very high-Isp ion thrusters, then kept in an heliocentric orbit ready to be commanded to intercept. (You'd need several of these so you could intercept within a month of command.)

I know that it's fun to speculate wildly, but there are some sources you could read out there about this. I've worked with the PI on the Deep Impact mission and he said that impacting that comet, which was 100 km wide, at 10 km/s, was very difficult to do. So trying to hit something even smaller at six times the relative velocity might be a little harder.

Nit to pick: The nucelus of the Temple 1 cometary target for Deep Impact was much smaller than 100 km, more like 6 km

Name             Dimensions    Density   Mass 
                     km              g/cm3      kg             
Halley's Comet 15 8 8   0.6       310^14
Tempel 1         7.64.9       0.62   7.910^13
19P/Borrelly     844        0.3       210^13
81P/Wild         5.54.03.3 0.6  ] 2.310^13
(from a well referenced Wikipedia article)

And Deep Impact did mange to hit close to the center of the sunlit area on the side of the fly-by, and was equiped to do so even if the nucelus had been irregular, rather than lumpy but nearly spherical.  Also, the impact was done with a very simple battery powered spacecraft using, IIRC, two lateral thrusters and a couple of roll control thrusters.  If the mission is destruction of a threatening comet or asteroid the top priority would no longer be having the majority of the spacecraft survive to send back data. 
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Comga

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #425 on: 02/21/2013 11:11 PM »
Or, how about a counter-orbiting impactor, giving a relative velocity of 60km/s, far beyond chemical explosives. Could be accelerated slowly using very high-Isp ion thrusters, then kept in an heliocentric orbit ready to be commanded to intercept. (You'd need several of these so you could intercept within a month of command.)

I know that it's fun to speculate wildly, but there are some sources you could read out there about this. I've worked with the PI on the Deep Impact mission and he said that impacting that comet, which was 100 km wide, at 10 km/s, was very difficult to do. So trying to hit something even smaller at six times the relative velocity might be a little harder.

Nit to pick: The nucelus of the Temple 1 cometary target for Deep Impact was much smaller than 100 km, more like 6 km

Name             Dimensions    Density   Mass 
                     km              g/cm3      kg             
Halley's Comet 15 8 8   0.6       310^14
Tempel 1         7.64.9       0.62   7.910^13
19P/Borrelly     844        0.3       210^13
81P/Wild         5.54.03.3 0.6  ] 2.310^13
(from a well referenced Wikipedia article)

And Deep Impact did mange to hit close to the center of the sunlit area on the side of the fly-by, and was equiped to do so even if the nucelus had been irregular, rather than lumpy but nearly spherical.  Also, the impact was done with a relatively simple battery powered spacecraft using, IIRC, two lateral thrusters and a couple of roll control thrusters.  If the mission is destruction of a threatening comet or asteroid the top priority would no longer be having the majority of the spacecraft survive to send back data. 
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online Robotbeat

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #426 on: 02/21/2013 11:24 PM »

Not entirely true, actually.

What's not entirely true? I said that life is still here. I think you'll find that is entirely true.  :)

The other point, that the impact of a Moon sized object could sterilize the Earth is probably true. But it obviously hasn't happened since life has arisen on this planet. The chance of that happening before the Sun becomes hot enough to destroy life on Earth is very small indeed. (There is apparently a few percent chance that the orbits of Mars or Mercury could become chaotic enough in four or five billions years time to cause planetary collisions.)

We don't have to worry about collisions of that magnitude. Impacts of objects the size of the Chelyabinsk meteor and up to kilometers in scale, we do, of course, have to worry about.
The "not entirely true" is referring to the Earth/moon impactor. If there was any life on Earth before that (probably not), then it would've been sterilized on Earth's surface by that impact. There are random things flying in space that could hit Earth and sterilize us again. Exceedingly unlikely (dismissively so), but possible. I was nitpicking. ;)
« Last Edit: 02/21/2013 11:26 PM by Robotbeat »
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Offline Archibald

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #427 on: 02/22/2013 07:04 AM »
For awhile, I was wondering how Russians were staying so calm driving their cars while this meteor lit up the sky. 
Chelyabinsk guys in Russia have a reputation for the most harsh. ;D
Type in a search engine "Суровые челябинские мужики настолько суровые, что" means "Harsh Chelyabinsk men are so harsh that" ;D

"Harsh Chelyabinsk men are so harsh that the fish jammed (concussied) by  meteorites" 
"Chelyabinsk residents are so severe that instead of snow in winter they are falling meteorites"
excuse my poor English


A few I understood:

Chelyabinsk guys are so tough, traffic cops bribe them.

Chelyabinsk programmers are so tough that they think
programming in assembler is a luxury -
they manually magnetize hard disk sectors.

Chelyabinsk vodka is so tough that it was banned as WMD
in 190 countries.

Chelyabinsk woodpeckers are so tough, they hollowed out
2 metro stations.

etc.


I see the point. It's just like the jokes with Chuck Norris or Zlatan Ibrahimovic...

Offline douglas100

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #428 on: 02/22/2013 07:46 AM »
I was nitpicking. ;)

So was I.  :)
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Offline Ben the Space Brit

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #430 on: 02/22/2013 09:55 AM »

Not entirely true, actually.

What's not entirely true? I said that life is still here. I think you'll find that is entirely true.  :)

It's true but misleading.

According to orthodox theory, life as we understand it appeared in the Cambrian explosion ~400 million years ago.  The heavy meteor bombardment stage of the solar system's history (when most of the Moon's craters were created, for example) occurred four billion years ago.

There have also been several occasions where a very large meteoric event came close to eradicating all life on Earth.  The infamous Yucatan Event is actually the smaller and less destructive of the two.  The other one occurred in the Deveronian period, IIRC, and took out about 90% of all vertebrate life.
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Offline jgoldader

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #431 on: 02/22/2013 10:37 AM »




It's true but misleading.

According to orthodox theory, life as we understand it appeared in the Cambrian explosion ~400 million years ago.  The heavy meteor bombardment stage of the solar system's history (when most of the Moon's craters were created, for example) occurred four billion years ago.

There have also been several occasions where a very large meteoric event came close to eradicating all life on Earth.  The infamous Yucatan Event is actually the smaller and less destructive of the two.  The other one occurred in the Deveronian period, IIRC, and took out about 90% of all vertebrate life.

The oldest microfossils go back to about 3.5 billion years ago, so prokaryotic life (cells without nuclei) was abundant by then.

The largest mass extinction known from the fossil record, which you mentioned, is the Permian-Triassic event, about 250 million years ago.  Marine life was almost wiped out, over 90% killed, and about 70% of land species as well.  As best as I can tell from a few quick searches, the P/T event's cause is still not quite pinned down, and it might have been a combination of too many stressors ranging from supervolcanism to an impact.

Though I recall reading many years ago that the greatest catastrophe for life on Earth might have been caused by... life on Earth.  The development of photosynthesis and the accompanying release of oxygen would have doomed the likely majority of single-celled organisms that relied on metabolizing inorganic chemicals (e.g., iron and sulphur compounds), for whom oxygen is a deadly poison.  Now that's a thought, brought me to a stop for a few minutes when I first read it.  The development of photosynthesis might have caused--literally--a genocide.

Jeff
Recovering astronomer

Offline JohnFornaro

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #432 on: 02/22/2013 01:05 PM »
As best as I can tell from a few quick searches, the [Permian-Triassic ] event's cause is still not quite pinned down, and it might have been a combination of too many stressors ranging from supervolcanism to an impact.

I took a googol on that too, and my search suggested that the cause was liberal tax and spend policies, leading to a fungal spike.
Sometimes I just flat out don't get it.

Online sanman

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #433 on: 02/22/2013 01:10 PM »
ProjectB612: If the dinosaurs had a space program, they'd still be here.

Fornaro: If the dinosaurs had fiscal restraint, they'd still be here.

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #434 on: 02/22/2013 02:15 PM »
Fiscal restraint, aka not making investments.
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Offline douglas100

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #435 on: 02/22/2013 02:16 PM »

The oldest microfossils go back to about 3.5 billion years ago, so prokaryotic life (cells without nuclei) was abundant by then.

The largest mass extinction known from the fossil record, which you mentioned, is the Permian-Triassic event, about 250 million years ago.  Marine life was almost wiped out, over 90% killed, and about 70% of land species as well.  As best as I can tell from a few quick searches, the P/T event's cause is still not quite pinned down, and it might have been a combination of too many stressors ranging from supervolcanism to an impact.

Jeff

Thank you Jeff, you beat me to the reply. My point was simply that in the billions of years since the start of life on Earth there was been no impacts large enough to sterilize the planet. (There have been, as you mention, impacts which have done severe damage to the biosphere.) Therefore, I suggest such impacts are very rare indeed and should not concern us when it comes to planetary defense. There is not a lot we could do about deflecting a planet sized impactor, anyway.
« Last Edit: 02/22/2013 02:18 PM by douglas100 »
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Offline douglas100

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #436 on: 02/22/2013 02:23 PM »

It's true but misleading.

It only seems misleading because you've got the history of the time of the start of life on Earth wrong.
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Offline smoliarm

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #437 on: 02/22/2013 03:16 PM »
ProjectB612: If the dinosaurs had a space program, they'd still be here.

Fornaro: If the dinosaurs had fiscal restraint, they'd still be here.

If the dinosaurs had a space program... we won't be here.

Offline go4mars

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #438 on: 02/22/2013 03:32 PM »
The largest mass extinction known from the fossil record, which you mentioned, is the Permian-Triassic event, about 250 million years ago.  Marine life was almost wiped out, over 90% killed, and about 70% of land species as well.  As best as I can tell from a few quick searches, the P/T event's cause is still not quite pinned down, and it might have been a combination of too many stressors ranging from supervolcanism to an impact.
There have been 5 very major mass extinction events.  "The big 5". 
I remember learning back in Uni days (from Charles Henderson, a P/T expert) that the Permian Triassic extinction was estimated to have completely erraticated 98% of species (not genera). 

Some guys figure the Permian/Triassic extinction was due to the the impact in Antarctica, which left a 500 km diameter crater.  Ever driven 500 kilometers?  That's a big impact.     Though somehow, "multi-causal" remains the consensus.

The 2% that lived weren't big complex creatures like us great apes.  Tough little fellers rather.
« Last Edit: 02/22/2013 03:36 PM by go4mars »
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Offline aquanaut99

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Re: Meteor Strikes Chelyabinsk, Russia
« Reply #439 on: 02/22/2013 03:45 PM »

Some guys figure the Permian/Triassic extinction was due to the the impact in Antarctica, which left a 500 km diameter crater.  Ever driven 500 kilometers?  That's a big impact. 

http://www.bbc.co.uk/nature/extinction_events

Current research seems to point that the P/T super-extinction (aka "The day life nearly died") may in fact have been caused by a "Murder on the Orient Express" (all the suspects are guilty) type scenario. It seems there were actually 3 extinction pulses, spread out over a total of 100'000 years (very short time geologically!).

The suspects (who may all be guilty):
- Eruption of the Siberian Traps. One of the most massive volcanic events in the past billion years, released a lava flow that covered much of present Siberia, and probably dumped immense quantities of CO2 into the atmosphere. Mean global temperature probably rose by at least 10 degrees F due to this alone. These eruptions correlate very well with the first extinction pulse.
- Major anoxic event in the oceans (possibly as a consequence of climate change)
- Vast release of H2S from oceans (probably a consequence of no. 2, anoxic situation and lots of dead organic stuff), leading to a poisoning of life on land
- Massive release of CH4 from methane clathrates in the ocean
- Massive impact forming the Wilkes Land Crater in Antarctica
- Formation of the supercontinent Pangea with associated change in Sea-level and sea circulation
« Last Edit: 02/22/2013 03:50 PM by aquanaut99 »

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