6 ms·

Fossil Diatoms in a New Carbonaceous Meteorite

45 points by brd 14y ago

GotAnyMegadeth 14y ago
It's down for me, I think this is a cached copy: http://webcache.googleusercontent.com/search?q=cache:http://www.buckingham.ac.uk/wp-content/uploads/2011/09/Polonnaruwa-meteorite.pdf http://webcache.googleusercontent.com/search?q=cache:http://...
jmillikin 14y ago
The article mentions that similar fossilized diatoms are found in terrestrial rock dating back to the time of the dinosaur's extinction (believed to be from a large impact). Is it possible that these meteorites are ejecta from that impact, or even an earlier one?
- zinssmeister 14y ago
  interesting. I guess we can't really exclude the possibility, that this fossilized diatom cam from earth, traveled through space and came back to earth?
  - jmillikin 14y ago
    It's also possible that live diatoms were ejected and subsequently fossilized. Or even possibly that they continued to live and reproduce in space (diatoms are ~algae, so they really only need water and sunlight).
  - daeken 14y ago
    Definitely can't exclude that, and it's a testable hypothesis. We can compare rock compositions and determine with a fair degree of accuracy if it's a match for a terrestrial source.
- p3d4nt 14y ago
  Ah, Occam's razor.
ComputerGuru 14y ago
This is a working mirror with images: http://www.buckingham.ac.uk.nyud.net/wp-content/uploads/2011/09/Polonnaruwa-meteorite.pdf http://www.buckingham.ac.uk.nyud.net/wp-content/uploads/2011... May be a bit slow, but it's complete and functional.
scrumper 14y ago
The Journal of Cosmology has rather a bad reputation. The fact that the meteorite only landed on earth three weeks before publication doesn't suggest that much review has gone on either. Don't get me wrong: I'd love for this to be actual, irrefutable evidence of extraterrestrial life and panspermia. It could even be that, but it's published in a crank paper unfortunately.
- zardoz90 14y ago
  If we look at one of the authors, Chandra Wickramasinghe, it's clear he has an obvious bias towards this sort of thing: http://en.wikipedia.org/wiki/Chandra_Wickramasinghe http://en.wikipedia.org/wiki/Chandra_Wickramasinghe
  - GotAnyMegadeth 14y ago
    > We report the discovery for the first time of diatom frustules in a carbonaceous meteorite thatfell in the North Central Province of Sri Lanka on 29 December 2012
    - zardoz90 14y ago
      Yeah, my bad, I was looking at the url.
  - jamespitts 14y ago
    Perhaps a better word is specialization. Most of us are armchair astrophysicists at best and we should not be so spontaneously dismissive. If there is something in all of this, we'll hear about it soon enough from the scientific community. In the meantime we should be conservative in how we depict the scientists and publications involved.
    - scrumper 14y ago
      That is well said. One might equally accuse Leonard Susskind of a bias towards string theory. Chandra Wickramasinghe isn't himself a crank, and that's what gives me hopes for this research.
zokier 14y ago
There seems to be some attacks against the authors and the publication. And seems like that is somewhat justified. But what about the interesting images? Assuming that they are authentic (and I believe that is a fair assumption even in the case that the authors are crackpots), they imho warrant closer look, even if you'd skip all the fluff that is the speculation from the authors.
rflrob 14y ago
The Red Rain cell claims (even with a question mark to indicate tentativeness) seem particularly bold. It's not difficult to imagine circular structures forming abiotically, and given that there are much likelier explanations for the red rain, I remain unconvinced.
- marze 14y ago
  If diatoms did arrive in meteorites and are the ancestors of Earthly diatoms, you would think they would have shown up in the fossil record earlier.
  - madaxe 14y ago
    Not really. Diatoms are tiny, and under the pressure of successive layers of sedimentation, silica (of which diatoms are largely comprised) will recrystallise at that scale, making detection of fossils difficult, if not impossible. I believe there are Precambrian diatom candidates, but unlike bacteria, which form colonies and therefore can still be found from ~3.5Ga (stromatolites and friends), diatoms are free-floating, and therefore easily lost in sediment.
    - marze 14y ago
      I see. What about candidates for a high silica rock that might have been metamorphized diatom deposits? If this theory was correct and diatoms were the original life form, it would suggest they might be more primitive, genetically, assuming little subsequent evolution.
      - madaxe 14y ago
        Indeed - I'd opine that the meteor in question was probably terrestrial in origin, as diatom genetics demonstrate that evolution is live and kicking in diatom populations. That said, it doesn't exclude the possibility of diatoms having perhaps taken a lengthy space trip at some point in their evolutionary history. It would certainly go some way to explaining why a marine species would have developed to be radiation and vacuum resistant. As to siliceous rocks - possibly, although I don't believe there's been anything found to suggest diatoms in great antiquity as yet. Funnily enough the most prevalent siliceous rock is... diatomite. Your toothpaste is made out of it. Chert (flint, etc.) is probably a better candidate substrate, but again, diatoms of that age would be indistinguishable from the substrate itself. Molecular clocks could indicate a biogenic origin, but as yet there's no way to demonstrate what variety of biogenic origin. There's evidence in terms of carbonaceous inclusions in ancient rocks that suggests the existence of life on earth before previously assumed - http://courses.washington.edu/bangblue/Mojzsis-3.85Ga_Akilia_d13C-Sci96.pdf http://courses.washington.edu/bangblue/Mojzsis-3.85Ga_Akilia..., but nothing to suggest it was diatomic in nature. Anyway. If their evidence isn't falsified, even if this isn't extrasolar panspermia, it's a demonstration that panspermia is possible.
marze 14y ago
Wow, that looks stronger than expected from the low-key presentation. I hope they can interest some other labs to attempt to double check their samples. "The universe, not humans, must have the final say to declare what the world is really like" indeed.
ChuckMcM 14y ago
That's a fun paper. One could argue (I'm not though) that only a crank journal would accept it for publication, but a better argument might be it doesn't really spend enough time to disprove itself. Such things are always more credible when the author takes time to try to disprove their own results by taking a different path through the data or use a different hypothesis. That said, the only way to irrefutably make this claim is going to be to sample comet fragments actually in space. If this particular comment (Encke) is the source then it should be possible to mount a mission to intercept this particular comments tail, and then return to earth orbit. Once there a recovery mission to get the material to the ISS and careful observation might quiet a number of skeptics.
- lotharbot 14y ago
  I'm really surprised they haven't done such a mission on Encke yet. It's a fairly obvious target for various explorations because its period is so short (3.3 years). (When I taught in an aerospace museum, one of our simulated space missions was launching a probe into Encke's tail: http://www.museumofflight.org/education/challenger-learning-center http://www.museumofflight.org/education/challenger-learning-... .)

45 points by brd 14y ago

It's down for me, I think this is a cached copy: http://webcache.googleusercontent.com/search?q=cache:http://www.buckingham.ac.uk/wp-content/uploads/2011/09/Polonnaruwa-meteorite.pdf http://webcache.googleusercontent.com/search?q=cache:http://...

jmillikin 14y ago

The article mentions that similar fossilized diatoms are found in terrestrial rock dating back to the time of the dinosaur's extinction (believed to be from a large impact). Is it possible that these meteorites are ejecta from that impact, or even an earlier one?

zinssmeister 14y ago
interesting. I guess we can't really exclude the possibility, that this fossilized diatom cam from earth, traveled through space and came back to earth?
- jmillikin 14y ago
  It's also possible that live diatoms were ejected and subsequently fossilized. Or even possibly that they continued to live and reproduce in space (diatoms are ~algae, so they really only need water and sunlight).
- daeken 14y ago
  Definitely can't exclude that, and it's a testable hypothesis. We can compare rock compositions and determine with a fair degree of accuracy if it's a match for a terrestrial source.
p3d4nt 14y ago
Ah, Occam's razor.

ComputerGuru 14y ago

This is a working mirror with images: http://www.buckingham.ac.uk.nyud.net/wp-content/uploads/2011/09/Polonnaruwa-meteorite.pdf http://www.buckingham.ac.uk.nyud.net/wp-content/uploads/2011... May be a bit slow, but it's complete and functional.

scrumper 14y ago

The Journal of Cosmology has rather a bad reputation. The fact that the meteorite only landed on earth three weeks before publication doesn't suggest that much review has gone on either. Don't get me wrong: I'd love for this to be actual, irrefutable evidence of extraterrestrial life and panspermia. It could even be that, but it's published in a crank paper unfortunately.

zardoz90 14y ago
If we look at one of the authors, Chandra Wickramasinghe, it's clear he has an obvious bias towards this sort of thing: http://en.wikipedia.org/wiki/Chandra_Wickramasinghe http://en.wikipedia.org/wiki/Chandra_Wickramasinghe
- GotAnyMegadeth 14y ago
  > We report the discovery for the first time of diatom frustules in a carbonaceous meteorite thatfell in the North Central Province of Sri Lanka on 29 December 2012
  - zardoz90 14y ago
    Yeah, my bad, I was looking at the url.
- jamespitts 14y ago
  Perhaps a better word is specialization. Most of us are armchair astrophysicists at best and we should not be so spontaneously dismissive. If there is something in all of this, we'll hear about it soon enough from the scientific community. In the meantime we should be conservative in how we depict the scientists and publications involved.
  - scrumper 14y ago
    That is well said. One might equally accuse Leonard Susskind of a bias towards string theory. Chandra Wickramasinghe isn't himself a crank, and that's what gives me hopes for this research.

zokier 14y ago

There seems to be some attacks against the authors and the publication. And seems like that is somewhat justified. But what about the interesting images? Assuming that they are authentic (and I believe that is a fair assumption even in the case that the authors are crackpots), they imho warrant closer look, even if you'd skip all the fluff that is the speculation from the authors.

rflrob 14y ago

The Red Rain cell claims (even with a question mark to indicate tentativeness) seem particularly bold. It's not difficult to imagine circular structures forming abiotically, and given that there are much likelier explanations for the red rain, I remain unconvinced.

marze 14y ago
If diatoms did arrive in meteorites and are the ancestors of Earthly diatoms, you would think they would have shown up in the fossil record earlier.
- madaxe 14y ago
  Not really. Diatoms are tiny, and under the pressure of successive layers of sedimentation, silica (of which diatoms are largely comprised) will recrystallise at that scale, making detection of fossils difficult, if not impossible. I believe there are Precambrian diatom candidates, but unlike bacteria, which form colonies and therefore can still be found from ~3.5Ga (stromatolites and friends), diatoms are free-floating, and therefore easily lost in sediment.
  - marze 14y ago
    I see. What about candidates for a high silica rock that might have been metamorphized diatom deposits? If this theory was correct and diatoms were the original life form, it would suggest they might be more primitive, genetically, assuming little subsequent evolution.
    - madaxe 14y ago
      Indeed - I'd opine that the meteor in question was probably terrestrial in origin, as diatom genetics demonstrate that evolution is live and kicking in diatom populations. That said, it doesn't exclude the possibility of diatoms having perhaps taken a lengthy space trip at some point in their evolutionary history. It would certainly go some way to explaining why a marine species would have developed to be radiation and vacuum resistant. As to siliceous rocks - possibly, although I don't believe there's been anything found to suggest diatoms in great antiquity as yet. Funnily enough the most prevalent siliceous rock is... diatomite. Your toothpaste is made out of it. Chert (flint, etc.) is probably a better candidate substrate, but again, diatoms of that age would be indistinguishable from the substrate itself. Molecular clocks could indicate a biogenic origin, but as yet there's no way to demonstrate what variety of biogenic origin. There's evidence in terms of carbonaceous inclusions in ancient rocks that suggests the existence of life on earth before previously assumed - http://courses.washington.edu/bangblue/Mojzsis-3.85Ga_Akilia_d13C-Sci96.pdf http://courses.washington.edu/bangblue/Mojzsis-3.85Ga_Akilia..., but nothing to suggest it was diatomic in nature. Anyway. If their evidence isn't falsified, even if this isn't extrasolar panspermia, it's a demonstration that panspermia is possible.

marze 14y ago

Wow, that looks stronger than expected from the low-key presentation. I hope they can interest some other labs to attempt to double check their samples. "The universe, not humans, must have the final say to declare what the world is really like" indeed.

ChuckMcM 14y ago

That's a fun paper. One could argue (I'm not though) that only a crank journal would accept it for publication, but a better argument might be it doesn't really spend enough time to disprove itself. Such things are always more credible when the author takes time to try to disprove their own results by taking a different path through the data or use a different hypothesis. That said, the only way to irrefutably make this claim is going to be to sample comet fragments actually in space. If this particular comment (Encke) is the source then it should be possible to mount a mission to intercept this particular comments tail, and then return to earth orbit. Once there a recovery mission to get the material to the ISS and careful observation might quiet a number of skeptics.

lotharbot 14y ago
I'm really surprised they haven't done such a mission on Encke yet. It's a fairly obvious target for various explorations because its period is so short (3.3 years). (When I taught in an aerospace museum, one of our simulated space missions was launching a probe into Encke's tail: http://www.museumofflight.org/education/challenger-learning-center http://www.museumofflight.org/education/challenger-learning-... .)