piterparker
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- Jul 20, 2021
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ok
please delete this post, sorry for wasting time
please delete this post, sorry for wasting time
Last edited:
meteorite from the orbit of the earth?
- Thread starter piterparker
- Start date
Red-Coat
Gold Member
Welcome to Tnet
It's an interesting question, for which the answer is broadly “yes, its theoretically possible, but rather unlikely, and none have yet been identified”. I’m making a distinction here between ejecta from impacts on earth that have been re-distributed but didn’t make it into orbit; versus material which was at least temporarily thrown high enough to be classed as “re-entry” material.
The potential name for such meteorites (if they exist) has been proposed as “Territe” and such territes will not be recognizable from simple observations of their lithology or geochemistry. They will have the same mineralogies as other Earth rocks and the only diagnostic feature would be a fusion crust formed during re-entry. However, this would not develop on many of Earth’s sedimentary rocks.
From a theoretical point of view the minimum crater size on Earth to produce such meteorites would be around 25km diameter and the launch velocity of the ejecta would need to be around 75% of the impact velocity. That would exceed most published estimates for imacts. Spallation could launch solid material at high velocities from a narrow and very shallow zone around the impact site, with vaporisation of volatiles in the target rock perhaps providing further acceleration.
For the high shock pressures associated with a suitably large Earth impact, any potential meteoroids would be small (probably <20cm diameter) and that also has implications for their survival during re-entry. Under typical re-entry conditions, most meteoroids from outer space need to be at least the size of a basketball for anything recoverable to reach Earth’s surface.
Confirmation of a meteorite of terrestrial origin would come from more detailed analysis of its isotopic state and anything from Earth would also be expected to have a relatively short Cosmic Ray Exposure age. I have a small specimen of NWA 6077 (possibly paired with NWA 5363 and NWA 5400) acquired some years ago, which created much excitement in that it had isotopic features which indicated it might be a territe. It classifies as an ungrouped achodnrite with brachinite-like mineralogy, but the oxygen isotope ration plots on the “Terrestrial Fractionation Line” (TFL).
The TFL plot is Indistinguishable from terrestrial rocks. Sadly, the Earth isotopic similarity is not seen for all elements. In particular, while there is observed similarity in O, Ni and Cr between the meteorite and terrestrial material, other elements such as Ca, Ti, Mo, and Ru are isotopically distinct from Earth materials. The parent body (or bodies, since the three paired meteorites exhibit some differences) remains a mystery, save to say that it had a number of Earth-like isotopies.
There is one other possible terrestrial meteorite that I know of but, although it may have come from Earth, it was found on the Moon. Examination of a piece of rock collected during the Apollo missions (Apollo 14 Lunar Breccia 14321) has indicated that it contains felsite fragments which formed under conditions not found on the Moon, but which are common on Earth.
Bear in mind that, if territes exist, we’re more likely to find them on the moon due to it proximity the Earth and the fact that it doesn’t have an atmosphere capable of causing shock-detonation or destructive ablation in the way that Earth’s atmosphere does
If your question is really “could these large chunks of rock I’m picturing be territes (from the Chicxulub impact or anywhere else)?” then I’m afraid the answer is “no”. They seem to be terrestrial conglomerates with no evidence that they’re impact-related..
It's an interesting question, for which the answer is broadly “yes, its theoretically possible, but rather unlikely, and none have yet been identified”. I’m making a distinction here between ejecta from impacts on earth that have been re-distributed but didn’t make it into orbit; versus material which was at least temporarily thrown high enough to be classed as “re-entry” material.
The potential name for such meteorites (if they exist) has been proposed as “Territe” and such territes will not be recognizable from simple observations of their lithology or geochemistry. They will have the same mineralogies as other Earth rocks and the only diagnostic feature would be a fusion crust formed during re-entry. However, this would not develop on many of Earth’s sedimentary rocks.
From a theoretical point of view the minimum crater size on Earth to produce such meteorites would be around 25km diameter and the launch velocity of the ejecta would need to be around 75% of the impact velocity. That would exceed most published estimates for imacts. Spallation could launch solid material at high velocities from a narrow and very shallow zone around the impact site, with vaporisation of volatiles in the target rock perhaps providing further acceleration.
For the high shock pressures associated with a suitably large Earth impact, any potential meteoroids would be small (probably <20cm diameter) and that also has implications for their survival during re-entry. Under typical re-entry conditions, most meteoroids from outer space need to be at least the size of a basketball for anything recoverable to reach Earth’s surface.
Confirmation of a meteorite of terrestrial origin would come from more detailed analysis of its isotopic state and anything from Earth would also be expected to have a relatively short Cosmic Ray Exposure age. I have a small specimen of NWA 6077 (possibly paired with NWA 5363 and NWA 5400) acquired some years ago, which created much excitement in that it had isotopic features which indicated it might be a territe. It classifies as an ungrouped achodnrite with brachinite-like mineralogy, but the oxygen isotope ration plots on the “Terrestrial Fractionation Line” (TFL).
The TFL plot is Indistinguishable from terrestrial rocks. Sadly, the Earth isotopic similarity is not seen for all elements. In particular, while there is observed similarity in O, Ni and Cr between the meteorite and terrestrial material, other elements such as Ca, Ti, Mo, and Ru are isotopically distinct from Earth materials. The parent body (or bodies, since the three paired meteorites exhibit some differences) remains a mystery, save to say that it had a number of Earth-like isotopies.
There is one other possible terrestrial meteorite that I know of but, although it may have come from Earth, it was found on the Moon. Examination of a piece of rock collected during the Apollo missions (Apollo 14 Lunar Breccia 14321) has indicated that it contains felsite fragments which formed under conditions not found on the Moon, but which are common on Earth.
Bear in mind that, if territes exist, we’re more likely to find them on the moon due to it proximity the Earth and the fact that it doesn’t have an atmosphere capable of causing shock-detonation or destructive ablation in the way that Earth’s atmosphere does
If your question is really “could these large chunks of rock I’m picturing be territes (from the Chicxulub impact or anywhere else)?” then I’m afraid the answer is “no”. They seem to be terrestrial conglomerates with no evidence that they’re impact-related..
Red-Coat
Gold Member
However you phrase the question, the answer is the same. That's not a meteorite and has no features to suggest it's impact related, nor anything to suggest it has seen atmospheric re-entry.
If you want to waste $30 you can get it tested as per the reply I gave here recently:
http://www.treasurenet.com/forums/meteorites/657859-25lb-stony-iron-meteorite-2.html#post6782430
If you want to waste $30 you can get it tested as per the reply I gave here recently:
http://www.treasurenet.com/forums/meteorites/657859-25lb-stony-iron-meteorite-2.html#post6782430
Red-Coat
Gold Member
It's never a waste of time when folks ask perfectly reasonable questions about unknown items and it results in answers or discussions from which learning can be derived. Sorry that you felt the need to delete your post, or if my answer made you feel uncomfortable. That wasn't my intention. In addition to many verifications of posted items, the forums are full of posts containing items which are not what the original poster hoped they might be.
- Jul 27, 2006
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[FONT="]piterparker[/FONT]
please do not completely delete the contents of the first post of a thread, it destroys the thread.
Red-Coat
Gold Member
Just for clarity, the original question was whether large impacts (eg Chicxulub) can result in Earth's own rocks being flung into orbit such that they ultimately fall back through the atmosphere in the same way as meteoroids from outer space.
Followed up with a suggestion that the pictured specimen(s?) exhibited features consistent with such an event (which they didn't) and then a question about what tests would be needed to confirm that.
Followed up with a suggestion that the pictured specimen(s?) exhibited features consistent with such an event (which they didn't) and then a question about what tests would be needed to confirm that.
augoldminer
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"The original question was whether large impacts (eg Chicxulub) can result in Earth's own rocks being flung into orbit such that they ultimately fall back through the atmosphere in the same way as meteoroids from outer space."
what you are describing may be tektites but they were only looked at as being suborbital from large inpacts on earth.
https://en.wikipedia.org/wiki/Tektite
https://www.meteorites-for-sale.com/tektites-for-sale.html
what you are describing may be tektites but they were only looked at as being suborbital from large inpacts on earth.
https://en.wikipedia.org/wiki/Tektite
https://www.meteorites-for-sale.com/tektites-for-sale.html
Red-Coat
Gold Member
The original pictures (now deleted by the OP) were definitely not tektites.
The hunter Awang
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Fraud expert, Be careful of this expert, talking to himself, he said a lot of crap, he really is an expert on himself,
Tpmetal
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why are you still here?
Fraud expert, Be careful of this expert, talking to himself, he said a lot of crap, he really is an expert on himself,
30 days in the Hole !
Use them to study the Rules ! http://www.treasurenet.com/index.php?pageid=rules
You were Warned !
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Red-Coat
Gold Member
I am genuinely mystified. Hunter Awang has posted this picture a couple of times, saying that the (apparently Chinese) person pictured is a liar and a fraud. There also seems to be a suggestion that he cheats people by saying rocks are meteorites when they are not, and/or is involved in some kind of conspiracy with the Purple Mountain Observatory (aka the Zijinshan Astronomical Observatory) in China to trick people into giving them meteorites by saying they are worthless rocks.
That’s as much as I am able to discern from the garbled accusations. I have no idea who this person is, except that the watermark on the picture shows it to have been taken from a Chinese meteorite forum. Awang referred to the person as “Zhao Zhiqiang”, and called him a “fake expert”; and then on one his posts said “Red-Coat, you are the Zhao Zhiqiang”; on another post he said “Red-Coat, he is Zhao Zhiqiang”.
If I read that correctly, among other delusions, Awang seems to be under the mistaken belief that I am Chinese and the person in the picture is me! Will the real Zhao Zhiqiang please stand up? Just to set the record straight, as those who know me will confirm, my name is Roger; I am not a fraud; I do have considerable experience in meteorites; I have certainly visited China but have zero percentage of Chinese heritage; and that isn’t me in the picture. This is me, with my wife on the left... she's also not Chinese, but 50:50 Anglo-Indian:
Probably the most accurate thing Awang has posted so far was the short comment: “Not many people here know anything about meteorite” and he seemingly puts me in that group but not himself. Fair enough. That’s his opinion. Other opinions are available.
Red-Coat
Gold Member
PS: if you zoom in on the picture, despite being no Brad Pitt, I think you'll agree that I don't look ever so Chinese. I had a quick check in the mirror just to be sure. My wife also agrees.
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