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Craters on Earth and the other Planets


Harry Costas

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Turtle, didn't you notice that you could get almost any stone to skip, depending on the angle and speed of the throw, or weren't/aren't you allowed to play with sharp objects?

 

 

 

There is little comparison of effects between or among skipping stones on a pond and large scale objects like planets and meteoroids. Some little thing called gravity if I recall? Tidal forces perhaps? Velocities in the thousands of miles per hour if I recall?

 

If I may ask, yet again, where do you come by this idea? Do you have any sources, other than you own speculation? Dare I say, some peer reviewed study? :turtle:

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There is little comparison of effects between or among skipping stones on a pond and large scale objects like planets and meteoroids. Some little thing called gravity if I recall? Tidal forces perhaps? Velocities in the thousands of miles per hour if I recall?

 

Turtle, you are becoming very arrogant in your behaviour towards me and your arguments are spurious.

 

It also appears that you have problems with conceptualisations and prefer abuse to debate over what you disagree about.

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Turtle, you are becoming very arrogant in your behaviour towards me and your arguments are spurious.

 

It also appears that you have problems with conceptualisations and prefer abuse to debate over what you disagree about.

 

You do not support your claim with any calculations or any sources indicating 'skip' events on the scale you suggest take place. It is not arrogant to ask for that here, it is de rigueur. :weather_storm:

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Laurie, the problem I (and I think Turtle) are having with your theory is that few bolides (practically none) fail to hit the Earth with other than a very large crunch that vaporises and destroys the body on impact. The energy of the impact far exceeds the internal yield strength of even the toughest impactor.

 

Indeed, for most small impactors, of typical differential velocity relative to the Earth, they will explode upon contact with the atmosphere. This is almost certainly what occured with the Tunguska event in 1907(?). American satellites designed to detect the flash of cold war nuclear tests have regularily picked up smaller aerial explosions caused by smaller versions of the same.

 

Note that recent observations have revealed the lack of structural integrity of stony asteroids and comets. These seem to be loose agglomerations of rubble and dust, rather than cohesive, unitary bodies. Dissolution with first contact with the atmosphere is thus all the more likely.

 

Thus we have three possibilities

a) Small objects - reduced to terminal velocity in atmosphere

:cup: Medium objects - destroyed in airburst by impact with atmosphere

c) Large objects - destroyed by impact on land (or water)

 

To achieve the skipping effect you describe would require the following combination of factors:

i) Low impact velocity - probability very, very low

ii) Large object - probability very low

iii) Structurally strong object - probability low

iv) Low angle impact - probability low

 

Now I concede that terms such as very low, or very, very low are qualitative, not quantitative. However, when you combine all of these factors the chances of such skip effects actually occuring become vanishlingly small, and certainly not quite common (i.e. multiple instances) as you suggest. I must echo Turtle's request that you need to offer much more than speculation for this proposal to be taken seriously.

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Turtle, you are becoming very arrogant in your behaviour towards me and your arguments are spurious.
I have carefully re-read the exchanges in this thread between you and Turtle. I fail to see how Turtle is becoming arrogant. True, he does not consider your hypothesis to be well founded. Surely that is based upon his assessment of the evidence provided and not upon any arrogance.

 

He has asked you several times:

a) How did you come by the idea?

:) Can you cite any research that would support it?

 

As far as I can see you have not responded directly to either of these requests. (You implied you got the idea from skipping stones on water. That's perfectly satisfactory - it's how Barnes Wallis developed the Dambuster's bombs in WWII.)

 

On the face of it then, you have an interesting idea that you concocted yourself, that has no evidence to support it. Turtle seems to be merely asking for well documented evidence.

 

I think you may be being a little oversensitive to his lighthearted approach.

It also appears that you have problems with conceptualisations and prefer abuse to debate over what you disagree about.
There is definitely no abuse present in Turtle's posts. The worst you can reasonably accuse him off is amused dismissal of your hypothesis. Let's focus on the facts and explore your idea further. Yes?
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Laurie, the problem I (and I think Turtle) are having with your theory is that few bolides (practically none) fail to hit the Earth with other than a very large crunch that vaporises and destroys the body on impact. The energy of the impact far exceeds the internal yield strength of even the toughest impactor.

.

.

.

 

Thus we have three possibilities

a) Small objects - reduced to terminal velocity in atmosphere

B) Medium objects - destroyed in airburst by impact with atmosphere

c) Large objects - destroyed by impact on land (or water)

 

I concur. Thanks for the summary Eclogite. :) While I do not have the calculus skills to write a limiting series of calculations for impactors, I do know what they should look like. The only category of impactor (meteorite) I would add is the 'iron', which is relatively rare and usually small by the time it reaches Earth. I think the largest ever found is the Willamette meteorite, a 15 ton monster. Because of their high density, this type of impactor simply burrows in and I think it is highly improbable as well that they would skip. :turtle: :cup:

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  • 7 months later...
Eh oh! You have just prompted me to some purely wild speculation. :hihi: What if, given the apparent frequency of Earth-impacting space-rocks, supervolcanoes originated with large impacts

 

 

a tentative but resounding yes! watching program now on Mark Boslow(sp) and his work to demonstrate antipodal focussing related to large Earth impactors which cause volcanic eruptions on the opposite side of Earth. Will look for more sources. :shrug: :shrug:

 

National Geographic Channel TV Schedule - Naked Science: Dino Meteor: Naked Science: Dino Meteor [TV-PG]

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Originally Posted by Turtle

Eh oh! You have just prompted me to some purely wild speculation. What if, given the apparent frequency of Earth-impacting space-rocks, supervolcanoes originated with large impacts‽

a tentative but resounding yes! watching program now on Mark Boslow(sp) and his work to demonstrate antipodal focussing related to large Earth impactors which cause volcanic eruptions on the opposite side of Earth. Will look for more sources. :) :confused:

 

National Geographic Channel TV Schedule - Naked Science: Dino Meteor: Naked Science: Dino Meteor [TV-PG]

 

The program airs again Sunday for any interested. The contention that a large meteor impacting Earth may cause volcanism at the antipode is well supported in the report. The primary interest in the program is the 'Great Dying" of 250 million years ago, and the case is made that the extensive shield volcanism in Russia at the time is directly a result of a large meteor impact off the N coast of Australia. The impact crater in fact was found by looking at the antipode of the volcanoes.

 

There is also experimental evidence for the action of antipodal focusing of impacts using the largest supercomputer on Earth to model the forces, (a bunch of Crays called Red something or other.) as well as mecanical experiments demonstrating the effect.

 

I'll report back after the next airing on Sunday with better references as to the principle investigators. :cup: :lol:

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I'll report back after the next airing on Sunday with better references as to the principle investigators. :hihi: ;)

 

Hello Turtle,

 

That would be interesting. I think I'm working then.

 

Also, that great rip on the surface of mars doesn't look like it was volcanic (antipode or otherwise), or a tectonic rift valley. Any idea's on how it could have formed considering the lack of a magnetic field and no liquid water?

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Hello Turtle,

 

That would be interesting. I think I'm working then.

 

Also, that great rip on the surface of mars doesn't look like it was volcanic (antipode or otherwise), or a tectonic rift valley. Any idea's on how it could have formed considering the lack of a magnetic field and no liquid water?

 

Not sure how you determined by looks the geology of the great rift valley. Mars did & does have water, and as i understand it once had a magnetic field.

 

Here are some sources I've found so far searching 'antipodal focusing'; Mars is mentioned in several. >>

 

 

Brian Shiro - Research

Antipodal Focusing of Planetary Impact Energy

 

Information Bridge: DOE Scientific and Technical Information - Sponsored by OSTI

 

Energy Citations Database (ECD) - Sponsored by OSTI

 

Information Bridge: DOE Scientific and Technical Information - Sponsored by OSTI

Axial Focusing of Impact Energy in the Earth’s Interior:

a Possible Link to Flood Basalts and Hotspots*

M. B. BOSLOUGH, E. P. CHAEL, T. G. TRUCANO,

D. A. CRAWFORD, and D. L. CAMPBELL

ABSTRACT

We present the results of shock physics and seismological computational simulations that show how energy from a large impact can be coupled to the interior of the Earth. The radiallydiverging shock wave generated by the impact decays to linearly elastic seismic waves. Thesewaves reconverge (minus attenuation) along the axis of symmetry between the impact and itsantipode. The locations that experience the most strain cycles with the largest amplitudes will dissipatethe most energy and have the largest increases in temperature (for a given attenuation efficiency).

We have shown that the locus of maximum energy deposition in the mantle lies along the impact axis. Moreover, the most intense focusing is within the asthenosphere at the antipode, within the range of depths where mechanical energy is most readily converted to heat. We propose that if large impacts on the Earth leave geological evidence anywhere other than the impact site itself, it will be at the antipode. We suggest that the most likely result of the focusing for a sufficiently large impact, consistent with features observed in the geological record, could be a flood basalt eruption at the antipode followed by hotspot volcanism. A direct prediction of this model

would be the existence of undiscovered impact structures whose reconstructed locations would be antipodal to flood basalt provinces, One such structure would be in the Indian Ocean, associated with the Columbia River Basalts and Yellowstone; another would be a second K/T impact structure in the Pacific Ocean, associated with the Deccan Traps and Reunion.

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Thanks Turtle,

 

Not sure how you determined by looks the geology of the great rift valley. Mars did & does have water, and as i understand it once had a magnetic field.

 

Mars Global Surveyor Magnetic Field Investigation

 

While Mars is very similar to Earth in rotation speed, its smaller size and further distance from the sun means that the geological time frame (with a magnetic field and liquid water, it spun around more slowly than Earth over a year) is too short for the martian great rift valley to be formed in a similar way to Earths. But, if Mars was spinning faster earlier and lost its magnetic field as it slowed down, it could occur in a similar way, but we should be able to measure this slowing down of the rotation speed.

 

Here are some sources I've found so far searching 'antipodal focusing'; Mars is mentioned in several. >>

 

The maps are pretty good and, along with the above, they leave several interesting questions with regards to the timing of the loss of Mars magnetic field, if Mars rotation isn't measurably slowing down.

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Thanks Turtle,

 

 

 

Mars Global Surveyor Magnetic Field Investigation

 

While Mars is very similar to Earth in rotation speed, its smaller size and further distance from the sun means that the geological time frame (with a magnetic field and liquid water, it spun around more slowly than Earth over a year) is too short for the martian great rift valley to be formed in a similar way to Earths. But, if Mars was spinning faster earlier and lost its magnetic field as it slowed down, it could occur in a similar way, but we should be able to measure this slowing down of the rotation speed.

 

 

The maps are pretty good and, along with the above, they leave several interesting questions with regards to the timing of the loss of Mars magnetic field, if Mars rotation isn't measurably slowing down.

 

You're welcome Laurie. I haven't studied so much the Martian geology, but I seem to recall the loss of the magnetic field there has been laid to the planets cooling? Watched a show last night on the NASA plans to send people to Mars and they talked about the idea Mars lost its atmosphere in part because it doesn't have enough gravity to hold on to it. That with a failing magnetic field which exposes the atmosphere to solar wind erosion, yes/no?

 

Given the lower gravity on Mars, it seems logical that mountains should (or at least could) reach greater heights, and with limited erosion going on they stay high. I hear one of the rovers is at risk due to a large dust-storm now active on Mars.

 

I have set up to record the NG show; I won't miss the names etcetera this time. :yeahthat:

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You're welcome Laurie. I haven't studied so much the Martian geology, but I seem to recall the loss of the magnetic field there has been laid to the planets cooling? Watched a show last night on the NASA plans to send people to Mars and they talked about the idea Mars lost its atmosphere in part because it doesn't have enough gravity to hold on to it. That with a failing magnetic field which exposes the atmosphere to solar wind erosion, yes/no?

 

Given the lower gravity on Mars, it seems logical that mountains should (or at least could) reach greater heights, and with limited erosion going on they stay high. I hear one of the rovers is at risk due to a large dust-storm now active on Mars.

 

I have set up to record the NG show; I won't miss the names etcetera this time. :yeahthat:

 

Hello Turtle,

 

There's still a bit of debate going on about Mars, the dynamo effect, the cooling/solidifying of the core and the loss of atmosphere. The link I posted referred to the solar wind increasing erosion and loss of water after the magnetic field loss/reduction so there is probably a link between them.

 

The dynamo effect is very interesting and it could also indicate other, just as massive, side effects from being hit by a large space rock, apart from antipodian volcanic rections i.e. if a planets rotation is slowed down or disrupted it could effect its internal dynamo to the extent that it loses its magnetic field.

 

Axial Focusing of Impact Energy in the Earth’s Interior:

a Possible Link to Flood Basalts and Hotspots*

We suggest that the most likely result of the focusing for a sufficiently large impact, consistent with features observed in the geological record, could be a flood basalt eruption at the antipode followed by hotspot volcanism.

 

A couple of years ago I read a book titled 'Written in Stone' by an Australian geologist who claimed that the newer layers of rock in north Queensland had been blown off by a past catacalysmic series of volcanic explosions that left much older layers exposed than would be expected. Unfortunately I cannot find the book or references to the title on the internet.

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Hello Turtle,

 

...

The dynamo effect is very interesting and it could also indicate other, just as massive, side effects from being hit by a large space rock, apart from antipodian volcanic rections i.e. if a planets rotation is slowed down or disrupted it could effect its internal dynamo to the extent that it loses its magnetic field.

 

A couple of years ago I read a book titled 'Written in Stone' by an Australian geologist who claimed that the newer layers of rock in north Queensland had been blown off by a past catacalysmic series of volcanic explosions that left much older layers exposed than would be expected. Unfortunately I cannot find the book or references to the title on the internet.

 

Hello Laurie. I'm off to review the recording just now. You bring an interesting point on the dynamo; I wonder if the 250,000 year event correlates to a record of a field reversal or weakening on Earth? Good stuff. :yeahthat:

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Hello Laurie. I'm off to review the recording just now. You bring an interesting point on the dynamo; I wonder if the 250,000 year event correlates to a record of a field reversal or weakening on Earth? Good stuff. :turtle:

 

OK, I have the info. The principle researcher on the antipodal focusing is Mark Boslough of Sandia National Labs; he describes himself as an impact physicist and he works on the Asteroid Defense program.

 

The computer he used to model the effect is called Red Storm, and operates at 41.5 terra flops. >> Sandia supercomputer to be world's fastest, yet smaller and less expensive than any competitor

 

Here's a couple more links on Professor Boslough. >> Discover magazine recognizes Sandia physicist Mark Boslough - January 8, 2007

 

Predicting an asteroid strike

 

Contrary to what I said earlier, the antipode to the Siberian traps shield eruptions of 250 million years ago is in Antartica, not off the coast of Australia. It was located by Professor Ralf vonFrese out of Ohio State University. More on the other scientists and their results after I review my notes. :cup: :turtle:

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...Contrary to what I said earlier, the antipode to the Siberian traps shield eruptions of 250 million years ago is in Antartica, not off the coast of Australia. It was located by Professor Ralf vonFrese out of Ohio State University. More on the other scientists and their results after I review my notes. :eek2: :)

 

I found we have a news story here at Hypog on the Antartica impact crater: >> http://hypography.com/forums/general-science-news/6918-killer-crater-found-under-ice-antarctica.html?highlight=meteor+impact

 

Another researcher featured on the program is Dr. Luann Barker from UC Santa Barbara. She is a geo-chemist and has developed a technique to find & isolate fullerenes which form during impact. Once isolated, gasses trapped in the fullerenes are subjected to analysis. She early on thought she'd find oxygen trapped and useable for dating the impact, but what she found was a type of helium found only in space. This is an entirely new tool now besides finding shocked minerals or tecktites or irridium, for positively ID'ing suspect impact sites.

 

Dr. Becker is developing instruments to go to Mars. >>

UCSB Press Release: "NASA Funds UCSB Researcher to Develop Instrument to Search for Past Life on Mars "

 

this research by Dr. Becker concerns an impact ending last the ice age. >> Ancient Meteor Blast May Have Caused Extinctions, Report UC Santa Barbara Scientists - Standard Newswire

 

:evil: :hyper:

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