Order of Kilopi
The theory that life spread ubiquitously throughout the galaxy through the action of comets, has been around for decades. The authors show some arguments for, and there will be those who are still against (and should be) until it is incontrovertible (which will be a while). Interesting though. pete
SEE:http://arxiv.org/ftp/arxiv/papers/1008/1008.3860.pdf
Established Member
This still strikes me as putting the cart before the horse a bit. It has yet to be proven that comets can have habitable environments, although it does seem possible to me. That is the first card in a tower of cards making up interstellar panspermia (in fact its the table on which the first card rests), and it isn't solid yet. I am against, although I'm glad some one is looking into the idea.
Established Member
Here's a paper that might be of interest to panspermists. Not cometary panspermia, but the formation of life not long after the big bang, the "biological big bang". The universe was a lot smaller then, so spread of life much more likely:
http://arxiv.org/abs/1009.1760
Order of Kilopi
Thanks pete, most interesting.Originally Posted by trinitree88
When examining those images are you given to thinking they represent biological remains or do you find geo chemical structures a more likely explanation?
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
You're right it's not proven, marsbug, it's an important question.
The Deep Impact mission revealed clays and carbonates in comet Tempel 1. These require water (which, where there's water there life) and we're not sure how they wold form within cometary bodies. It's a bit suggestive to me of course.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
Yes, to me, it seems more likely that life arose as soon as possible in the early universe and has since spread and adapted to many environments than it does that life arose on Earth only 4G yrs ago and is isolated, as if an island surrounded by an utterly dead sea.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
Just the usual caveat, where there's (liquid) water there's the potential for life.
STARGAZING: All I see are the lights of a billion places I'll never go. --Howard Tayler, Schlock Mercenary
Established Member
The Earth is part of the universe. You cannot assume some mystical property of the universe that lead to life elsewhere but not on Earth. What is so special about any other place in the universe? What do molecular clouds or stellar nebulae (or comets) have that Earth does not? Certainly the laws of physics and chemistry are no different. Earth, after all, was formed in a stellar nebula which formed from a molecular cloud.
What does "as soon as possible" mean? If life evolved in a hundred million years in the early universe, why could it not also evolve in a hundred million years on the Earth?
If life could evolve in a rarefied molecular cloud at very slow reaction rates, why could it not evolve much more quickly on Earth which has the same atomic ingredients, much higher reaction rates, and much greater conservation of reaction products?
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Panspermia is so testable, why don't we organize a movement to encourage an international space-borne pietre dish experiment? Experiments: The module should be simple small and easily incorporated into other designs. The probe should lift the lid on sterile sticky media during meteor showers and any other opportunity to sample and return as an add-on to other missions.
But then, in a way the moon samples should have been a good "media" for space spores, not so? Why were those samples sterile if panspermia is afoot?
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I've spent the last few days researching a blog post on exploring comets (small hint) so I can add that ; the russian vega mission revealed the surface of Halleys comet was in the 300 to 400 degrees kelvin range of temperature, which is appropriate for liquid water, that of all the comets visited to date only wild 2 has little sign of carbonates or phyllosilicates (it is believed to have only migrated to the warm inner system relatively recently), and that organic chemistry even in wild 2 has progressed as far as the simplest amino acid, glycine.You're right it's not proven, marsbug, it's an important question.
The Deep Impact mission revealed clays and carbonates in comet Tempel 1. These require water (which, where there's water there life) and we're not sure how they wold form within cometary bodies. It's a bit suggestive to me of course.
So, suggestive of liquid water? Yes, even, I'd go so far as to say, suspiciously like its been there. Proof of life on comets? Hardly. Although lots of organics and recurring liquid water (if that is proved) make them as interesting as many outer solar systems moons or even Mars in that regard. To boot, cometary surfaces are more accessable than the oceans of Europa, or Ganymede and the low gravity makes sample return a relative doddle compared to Mars. Of course you have to run the gauntlet of high speed dust particles, which is what did for the Giotto missons camera.
If there are or have been habitable environments and life on comets, thats not proof positive of interstellar panspermia: for that we need an example of extra-solarsystem life, and we need to be able to trace both us and them back to a single source. Thats a big tower of cards that will take a long time (I think centuries at least) to construct. I think focusing on the issue of transient liquid water zones on comets is a good bit of science for now, and I'm happy to leave interstellar panspermia to future generations.
Edit: @ A.DIM:
I hope I'm not pushing the skepticism too hard here, but i want to be clear on my opinons; pre-biotic chemistry on comets, yes thats been proven; liquid water on comets, cetainly possible even probable; past or present life on comets, cant say but worth investigateing. Interstellar panspermia? I think thats a huge leap from where the evidence has us at right now.
@ Procyan: I'm not sure Lunar samples are the best place to look for spores, even taking into account the recent discoveries of very small amounts of surface water and lots of possible polar ice.
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You're right. any life "seeds" falling to the Moon would accelerate to destructively high speeds in the vacuum like little tiny meteors. So lunar dust wold not have viable spores but might have a load of protein-veniered motes. I hate using the word spores in this context because it has such a precise meaning. We should call them spore-like objects from space or SLOFs, no, I meant Exo-viable Elementary Gellybeans. sorry
I think the Fred Hoyle camp has covered this, but is there any hard data on the maximum height to which Earth sourced spores can loft on natural air currents? Of course a bug from earth would fall back into the atm even if it somehow made it into the thin air. right?
Order of Kilopi
Yes, of course.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
I assume no mystical properties centsworth II, just chemistry and physics (although I did see recently an article about the laws of physics being variable across the universe).
The ingredients for life as we know it were available in large quantities as early as 10G yrs ago, and perhaps even earlier as discussed in this space com article: Could Life Be 12 Billion Years Old?
If all the ingredients for life were available so long ago what precludes the probability of its origin so long ago?
Life is on Earth so we assume it originated here; I get it, and certainly agree it's possible.
I simply think it's more probable to have originated as soon as the ingredients / environments were available in the early universe.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
Well, there is some possible evidence for Microorganisms from the moon.
But I'd have to say panspermia is being tested, in many ways, and is a growing theory within the astrobiology community.
Here you can read about many tests (scroll down).
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
marsbug, I find your input interesting and sometimes challenging. I take no offense from your skepticism. It's a necessary, indeed integral part of the scientific process. Panspermia is a longstanding scientific theory and has endured much sketpicism. With supportive evidences growing in recent years, ballistic panspermia (betwixt planets, moons, etc.) has become more accepted. However, I fail to view our solar system as a closed system. It seems there exist plenty mechansims for interstellar transport of life or its detritus (implying genetic input) whether from galactic collision, supernovae, stellar flybys, rogue planets... comets and dust. For me, it's not such a huge leap.
If I were on a remote island, covered in life and surrounded by a seemingly inhospitable sea, should I assume life originated there?
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
Discussion of this with mutliple cites and reference found here.
Succinctly, the tropopause is thought to act as a barrier for life reaching heights above 18km but there have been microbes found in the stratosphere. "Are they inbound or outbound" is the question.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Established Member
It seems like tropopause is not that good barrier as thought previously.
It should not be a hard question. I except that alien life will be significantly different from Earth life. Quote from this topic, "These microbes are essentially the same as those found on Earth", create very serious problem for any proposition that claims these microbes are incoming. I see this fact as very good proof that these microbes are exclusively from Earth.
Senior Member
Here's what I don't "get". A.DIM looks at life originating on Earth, something for which we have abundant evidence for, and only allows a "possible" for it's likelyhood, yet the idea that life started somewhere else, something for which we lack evidence, and considers it "more probable" than life originating here.
It's the scientific method on the Bizarro world.
A.DIM...do you still maintain that you are not "promoting" panspermia?
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@ MaDeR
The panspermia point of view essentially argues that alien life is Earth life, so I'm not sure that 'alien life will be significantly different' holds up.
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Gotta call you on that; in the bizzaro world A.DIM would be building a giant robot battletank.
Why has this become an either/or? life originating on earth does not preclude it also originating elsewhere, perhaps in a very similar form.
Senior Member
I have no difficulties with multiple origins.
eta...oh and marsbug, 2 "R's" in Bizarro.
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Cusses! I mean curses!! Mwahahahaha! 'k I'm getting carried away by the Bizarro thang.
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I have no difficulties with multiple origins.
eta...oh and marsbug, 2 "R's" in Bizarro.This is the point where it seems to me the conversation his heading for either/or terrestrial/space origins. If the law of mediocrity holds true then life should have begun wherever the initial conditons (whatever those are) are met. So if those conditions were met 12 billion years ago then, yes, life should have arisen then, but that does not mean we couldn't be a product of an independant origin here on Earth.
Bear in mind, what has become more accepted is that ballistic lithopanspermia is in principle possible; no non-controversial evidence that it has actualy happened has come to light as far as I know.
I can follow your logic wrt interstellar panspermia, expecially considering that conditions were much more favorable for it when our solar system was young and part of a dense packed open cluster, but again, there is no evidence that is has actualy occured. Great theory without evidence is ultimately just very clever spectulation.
If the island is all you have ever known, and the sea is dead as far as you can tell, then yes the logical assumption is that the island life is all there is.
Doesn't mean you close your mind to the idea of extra-island life, refuse to theorize about it, or refuse to accept incontrovertable proof ( a lizard on a drift wood branch, the QE2, whatever) if it does come along, but to assume that other life exists without seeing it is just as illogical as denying it when you do see it.
Established Member
Nothing.
It is the prospect of life passively traveling tens or hundreds of light years to seed itself on Earth that I find precluded by the vast distances and harsh environments involved in such a voyage.
Such a physical/chemical imperative for life would have lead to its origination across the universe -- including on Earth.
If it is true that life originates as soon as the ingredients/environments are available, I expect that life would have originated in many places in the universe 10G years ago, just as I expect it originated on Earth 4G years ago.
Last edited by centsworth_II; 2010-Sep-13 at 11:42 PM.
Order of Kilopi
Well, it was never considered a "hard" barrier; particularly strong tropical storms can apparently push through it.
So they're outbound yes?It should not be a hard question.
As marsbug correctly points out, if panspermia theories are correct, Earth life already resembles its ancestors.I except that alien life will be significantly different from Earth life. Quote from this topic, "These microbes are essentially the same as those found on Earth", create very serious problem for any proposition that claims these microbes are incoming. I see this fact as very good proof that these microbes are exclusively from Earth.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
What abundant evidence for life originating on Earth do we have?
That it's here and shares common ancestry? That it appeared as soon as Earth was habitable?
To me our single example of life, here on Earth, says nothing of its origins. Until it can be shown that abiogenesis occurs in whatever proposed early Earth scenario your argument is no more valid, more probable, than Bizzarro's.
Yes.A.DIM...do you still maintain that you are not "promoting" panspermia?
To what end? I would ask.
As you should know, panspermia is a longstanding scientific theory enduring much skepticism for many years, yet it persists, gaining momentum in recent years and being a significant part of astrobiology research. Is not Life in Space here at BAUT an appropriate forum in which to discuss the idea? Part of the scientific process involves varying schools of thought; the origin of life is an open question. You act as if the question has been answered and there is only one school of thought. Hell, even within abiogenesis we find no single theory accepted!
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
I don't know marsbug, I think in bizzarro world I'd be a Thought Adjuster, building and installing nanobots which look like bacteria and viruses...
Indeed.Why has this become an either/or? life originating on earth does not preclude it also originating elsewhere, perhaps in a very similar form.
It could be happening everywhere all the time, from time immemorial.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
Certainly, but to me it seems (using life on Earth as an example) one type of life will spread and monopolize. There may have been multiple origins of life here on Earth, no?
What would preclude this from having happened in our universe? It does seem especially suited to life as we know it...
I concur our single example of life tells us little either way, but it would seem much of space science operates on the assumption that life is out there, no?Bear in mind, what has become more accepted is that ballistic lithopanspermia is in principle possible; no non-controversial evidence that it has actualy happened has come to light as far as I know.
I can follow your logic wrt interstellar panspermia, expecially considering that conditions were much more favorable for it when our solar system was young and part of a dense packed open cluster, but again, there is no evidence that is has actualy occured. Great theory without evidence is ultimately just very clever spectulation.
If the island is all you have ever known, and the sea is dead as far as you can tell, then yes the logical assumption is that the island life is all there is.
Doesn't mean you close your mind to the idea of extra-island life, refuse to theorize about it, or refuse to accept incontrovertable proof ( a lizard on a drift wood branch, the QE2, whatever) if it does come along, but to assume that other life exists without seeing it is just as illogical as denying it when you do see it.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Order of Kilopi
I understand but it seems there are mechanisms aplenty for transport: galactic collisions, supernovae, rogue stars, far flung comets.
Again, I tend to think life in the universe has had time to spread, reaching Earth by 4G years ago.Such a physical/chemical imperative for life would have lead to its origination across the universe -- including on Earth.
If it is true that life originates as soon as the ingredients/environments are available, I expect that life would have originated in many places in the universe 10G years ago, just as I expect it originated on Earth 4G years ago.
Here's something new, relevant: Comets may have brought life to Earth: New study.
I note: Origins of life research initially focused on the production of amino acids from organic materials already present on the planet. However, further research showed that Earth’s atmospheric conditions consisted mainly of carbon dioxide, nitrogen and water. Shock-heating experiments and calculations eventually proved that synthesis of organic molecules necessary for amino acid production will not occur in this type of environment.
Sounds like a blow to abiogenesis on Earth theories, at least for somewhere on the surface. And as I understand it, Russell's hydrothermal vents are too diffuse, diluted, to actually have produced molecules.
To me it stands to reason we look off planet when considering origin of life theories.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Established Member
Nothing preculdes it, but there is no evidence in support of either multiple origins here on Earth or out in space. There is little evidence of any kind on how and where life originated, other than the presence of life on Earth for the last 3 or 4 billion years. This is the only direct, uncontroversial, evidence of life we have anywhere in the universe.
No. In some quarters there may be an assumption of extraterrestrial life, but in my view this is selling the magnitude and importance of finding such life short.
In general space exploration operates on the basis that alien life might be possible, and might be detectable. It also operates on the proven knowledge that terrestrial life is related to pre-biotic chemistry that we can observe happening on other regions of space today.
EDIT:
It also operates on the basis that, and this is pet peeve of mine, the search for life in space is not the only valid reason for exploring it (although it is a fascinateing and compelling one), and that things as simple and beautifull as alien weather, or geology, which we know exist, can be equally important and fascinating. Hence I would assert that panspermia, ballistic or cometary, is an idea that we can afford to sit on until we find truly solid proof for or against. It does not need to be argued out, and that will not-I predict-settle anything or change any minds. It needs to be treated with patience while we wait for more evidence.
Exploring comets is an active field, with lots of interest even from people who'd swear that the very notion of cometary life, never mind panspermia, is balderdash. Have patience A.DIM, there will be good chances to see if that part of interstellar panspermia theory holds up.
Am I ranting? I'm ranting, I'll get my coat....
Last edited by marsbug; 2010-Sep-14 at 04:50 PM. Reason: clarity, punctuation, spelling
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