Did life here begin out there?

By Phil Plait | February 26, 2008 4:01 pm

Panspermia is the idea that life on Earth originated in space and was seeded here by some event. This covers a lot of ground sky: comets, Mars, Venus, aliens, and so on.

The idea isn’t as far-fetched as it sounds. It’s more medium-fetched. Mars is smaller and farther from the Sun, so therefore it cooled faster than Earth did after the period of heavy asteroid and comet bombardment a billion or so years after the planets formed. It may have had oceans and better conditions for the start of basic life before the Earth had cooled enough.

But if life started up first on Mars, how did it get here?

Asteroid impacts. The idea is that a smallish asteroid could have hit Mars and launched quite a bit of Martian territory into space. Eventually this could hit Earth. We know this can happen; we have samples of meteorites that are clearly form Mars; the isotope ratios of the chemicals in the meteorites matches what we know of Mars’s atmosphere. Heck, I used to own a small Mars meteorite myself, until it fell out of my bag and I lost it, arrrrggggg!

Anyway, if some of that Martian ground had bugs in it of the protozoan kind, then they could make it to Earth.

Of course, there are hazards. They’re in space a long time, so they have to survive that. They also have to survive the fall to Earth. It’s not clear they could live through either event. And before that, they have to survive the enormous pressure of being smacked by an asteroid impact.

But a new paper that just came out in the peer-reviewed journal Astrobiology says that some bacteria could, in fact, survive the initial launch event. Amazingly, the enormous pressure generated in an asteroid impact on the surface of Mars may be survivable, if you’re really really tiny.

The researcher made models of the Martian ground seeded with bacteria, then subjected these samples to the pressures expected in an impact event. Amazingly, many of the bacteria survived. Lichens and bacteriospores did the best, surviving pressures from 5 – 40 billion Pascals, which is about 50,000 to 400,000 atmospheric pressures. That’s a lot. Cyanobacteria were the wussies of the lot, only surviving up to 100,000 atmospheric pressures.

Mind you, a human would be less than a greasy smear at that kind of pressure.

Anyway, this is pretty interesting stuff. It doesn’t say that the buggers could survive the trip here (millions of years) and the entry into our atmosphere, but there are scenarios where those are possible.

On a personal note, I think panspermia is interesting and worth investigating, but some people think it’s the panacea to everything. Notably an astronomer named Chandra Wickramasinghe, who has made the fun claims that interstellar dust is actually made of clouds of E. coli, and that the flu is really a virus from space.

Right.

Still, when the study stays scientific, it’s worth a look. I have seen no evidence at all that we actually did start on Mars or a comet or Somewhere Else, but it’s still possible such evidence will turn up. When we get to Mars, for example, what if we find DNA-based life? It’s much easier to get a rock from Mars to Earth than vice-versa (due to orbital and gravitational mechanics), so a find like that would be pretty conclusive. Until then, we have to do what we can to figure out what it was like for such interplanetary interlopers each step of the way. And the first step appears to be viable.

Oh– I cover some of this in my upcoming book, too. After all, if bugs might have made it here three billion years ago, they might make it today. Can we get wiped out by alien bacteria? Well, no, but read the book anyway.

Tip o’ the Whipple Shield to SpaceRef.

Comments (72)

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  1. Met

    Doesn’t Sagan bring up the idea in Pale Blue Dot?

  2. Chris Reed

    For some reason, I read the headline to this story with Patrick Mcnee’s voice in my head…… Then an orchestra started playing….

    I think it was the theme from Airplane II.

  3. Chip

    Concerning the picture in your blog post, that Balok sure gets around.
    http://memory-alpha.org/en/wiki/Balok

    Corbomite rules!

  4. Earth being seeded by meteorites from Mars? That’s just plain silly. As a true believer in the Church of FSM, I shall let my faith guide my scientific beliefs.

  5. Chip: Not only does it rule, Corbomite Maneuvers!

  6. Even though panspermia is an out there concept, it is scientific because it is more testable than the occam-shaved hypothesis that life started here on Earth. This is because the Earth doesn’t preserve enough early rocks for us to be able to check them for signs of life. I should probably blog about this sometime…

  7. Ken Youngstrom

    Isn’t this rather like the conjecture that the plays of Shakespeare were actually written by another guy with the same name? Doesn’t seem to get you anywhere, does it?

  8. Donnie B.

    Ken: good point. Even if life didn’t originate here, it had to originate *somewhere*. You have the same problem explaining the latter as the former (except perhaps with a wider variety of possible environments for it to originate in). You also need to explain why life that originated “out there” managed to thrive “down here”, where the environment is (most likely) so very different.

  9. Ken, actually, it does have some implications. Mars is dead now, but Earth wasn’t a good place when Mars was looking pretty tasty for life. Eventually, we’ll look elsewhere for life. Will we look at mars-like worlds or Earth-like ones?

    What if it turns out life is hard to generate on Earth-sized planets? It has implications for the durability of life. If it started on Mars, it didn’t last long. What does that say about how long life can hang out on a planet?

  10. Interstellar dust made of clouds of E. coli? Nonsense! Then again, the T4 bacteriophage is obviously an alien, and I understand it eats E. coli. So maybe these “clouds” are actually farms for feeding teeming masses of T4 bacteriophages!

    http://www.nsf.gov/od/lpa/news/02/pr0207images.htm

    I, for one, welcome out T4 bacteriophage masters…

  11. Willem A. Heiting

    What I know is that it is known that bacterial life could survive an impact, a launch, a voyage and the impact of the debris it’s living in. Aren’t scientists anxious with sending spacecraft to other worlds/moons because of contamination risks?

  12. Crux Australis

    And by Paschals I guess you mean Pascals. Which brings me to a sticking point for me…if the unit is named after a person, should it have an upper case initial (Volt, Amp, Newton, Joule, Pascal)? I think so. Any other points of view? Sorry if I’m hijacking the conversation.

  13. Ian

    Crux Australis: No, because unlike the person that they’re named after, the units are not proper nouns.

  14. Of course, whether or not life came from space doesn’t really answer the important question… how did life arise from the nothingness. That’s the question, the answer to which will cause religion to at least make up new fantasies.

  15. J. D. Mack

    The flu isn’t a virus from outer space – language is!

    J. D.

  16. Jim

    Arthur C. Clarke had an article about our emigration to the stars beginning with a cycling of the Space Shuttle john and light pressure whisking our descendants to their destiny. Radiation has been cited as a limiting factor in commode-spermia, however. If it were embedded deep within a rock or comet, it would be more likely to survive a trip.

  17. Ah, I did misspell Pascal. Nuts.

    As far as abbreviations for units, we used to argue about that at my last job. Was it 10 Newtons or 10 newtons. I think that once you’ve taken a name and made it a unit, it should be lower case. But in general we found that the unit is capitalized, like W for Watts. However, I usually see amps as a little “a”. Maybe it’s Amperes, but amps. Weird.

  18. RayCeeYa

    Panspermia is one of my favorite examples of real science emulating science fiction. Sci-Fi just usually got the level of evolution wrong.

    One of my favorites is the Twilight Zone Episode “Probe 7″. This is the one where a man fleeing nuclear war on his home planet seeks refuge on an alien world. There he meets a strange woman from another world who at first fears and attacks him but later they begin to understand one another.

    Quote from the closing narration,

    Do you know these people? Names familiar, are they? They lived a long time ago. Perhaps they’re part fable, perhaps their part fantasy. And perhaps the place they’re walking to now is not really called ‘Eden’. We offer it only as a presumption. This has been the Twilight Zone.

    In reality the odds of two higher beings from different planets being genetically compatible are absurd. However we now know for a fact that asexual single celled bacteria from different species trade genes all the time.

    We are only beginning to understand the influence horizontal gene transfer has on evolution.

    So did life begin on Earth or Mars first?

    Perhaps as an unlikely third option life began on both Mars and Earth. And perhaps there is still some of that Martian DNA in us. Unfortunately, any evidence of such would be so far back in time that we will most likely never know.

  19. Reminds me of Andromeda Strain, which may be my favorite Crichton book.

  20. Another fictional reference from “Quatermass and the Pit” (1967):

    “We are the Martians”

  21. Space Cadet

    Whenever I read something about how lifi came from Mars or a comet or (you fill in the blank), I wonder why life couldn’t have just started here. We’ve got living things in some pretty severe environments here. We’ve seen that living things can change to adapt to a changing environment. What makes people assume life came from somewhere else?

    Maybe life starts all over the place. Maybe there was a time when Mars was just prime for life to spring up, and just when there was all sorts of stuff starting to grow, things started changing faster than they could adapt. Maybe there was a time when Earth, too, was just prime for life to start, and we were luckier. We evolved past the capacity to carve crude faces into sand dunes.

  22. Jeff Fite

    I think RayCeeYa is on to something. I know a little geology, and a fair chunk of biology and medicine, and I believe (but cannot prove) that self-replicating chemistry will arise wherever conditions permit.

    You need a suitable solvent–water is pretty good, but people can dream up all sorts of alternatives if you don’t mind thinking about exotic environments.

    You need atoms that readily make and break chemical bonds in the environment you have in mind. Again, I vote for the usual suspects, carbon, nitrogen, oxygen and hydrogen (and some other stuff for flavor), because they are abundant and low on the periodic table–making for fairly low-energy chemical bonds. (Although the exotically-minded again will be chanting, “Silicon! Silicon!”)

    You need an energy source that’s not too hot and not too cold. This part is critical. Any chaotic system (meaning one which behaves within its phase-space around a strange attractor) will have certain portions of its phase space where very little happens, then a self-regulating behavior or pattern will appear as the system gets more active, and finally the order will dissolve as the system’s activity becomes too disruptive.

    [There are chemical reactions that have different colors at different pH’s–think liquid litmus paper. You can vary either the concentration of the reagents or the temperature of the solution to make the reaction more or less energetic. There’s a sweet spot between “too slow” and “too fast” that demonstrates swirls of pink and blue solution spinning around one another, splitting off ‘daughter’ swirls to blur away and dissolve, until new swirls form again out of the seething purple fog.

    Another example: a pot of water on a stove. Heat it slowly and watch. As it gets close to boiling, you’ll see little bubbles of superheated steam appear at random on the bottom of the pan. Later, with a bit more total heat in the system, roughly-hexagonal cells of steam will form in in a (mostly) regular pattern of close-to-uniform size. Get a little hotter, and the hexagonal bubbles are destroyed.]

    I love it when young-Earth creationists try to throw the 2nd law of thermodynamics at me. Most of them forget that the Earth is NOT a closed system, doomed to dissolve into ever-increasing entropy. We are ALL solar powered!

    Finally, you need time. And every time someone finds an older fossil, or a more-primitive archaeobacteria, the minimum time necessary gets a little smaller.

    I think, given those four ingredients, life will inevitably arise.

    I also think that RNA and DNA seem to be pretty good self-replicating chemicals, with enough variability that natural selection can’t HELP but make ever-more complex organisms. But, I have to admit that I may be a “nucleic acid chauvinist.” I can’t help it–I was born this way.

    Finally, it seems to me that, given the above, and the research that Phil has blogged about, as well as the hypothetical possibility that meteoroids can transfer between any two adjacent bodies in the solar system*, and the surprising number of extremophile microorganisms that exist in preposterous places on Earth…

    We will find life everywhere in the solar system that has or once had liquid water for half a billion years–and it will all be chemically related to us.

    Panspermia, indeed.

    All the above is dubiously-informed speculation by a science (and science-fiction) fan. But I like the idea.

    *(BA, I know that going out an orbit is a lot harder than going down. Still, couldn’t those so-far hypothetical martian critter wind up in Europa’s ocean?)

    Evolving Squid, I’d love to hear your thoughts.

  23. Geez, you are all all over the map with the scifi references.

    Yet you missed the one from classic Battlestar Galactica. Sheesh.

  24. Ken G

    I think there may be a flaw in this logic from the BA’s blog:
    “When we get to Mars, for example, what if we find DNA-based life? It’s much easier to get a rock from Mars to Earth than vice-versa (due to orbital and gravitational mechanics), so a find like that would be pretty conclusive.” The interesting point here is that if you knew the life had the same origin, then it is more likely to have gone from Mars to Earth, that is a good point. But would DNA-based life really be proof that it had the same origin, or just evidence that DNA-based life is a typical channel for life to develop? The basic problem has been laid out above– it could have happened on Mars, it could have happened on Earth too.

    I am with Ken Youngston here, that if life is to begin spontaneously on some planet, it is far easier for it to just do so on the planet with the environment it must eventually flourish on. What does starting somewhere else win you? A billion years of time, yes, but look at it this way. Either life is rare on planets like Earth (and Mars when its climate was better), in which case the billion year head start panspermia gives you is irrelevant next to the unlikeliness of it starting on either planet, or else life is common, and then panspermia is not needed as a cause for life, but rather is just a kind of competing influence.

    In the latter case, the question is not whether or not it could get to Earth, it is whether or not the billion-year head start could “beat out” the life that would have eventually developed on Earth were there no Mars. Does a head start like that compensate for the different environment? If life is popping up independently on Earth and Mars, how many independent channels are there on Earth itself? We don’t see evidence of that argument being made at all, yet we would need to if panspermia is to be important.

  25. TheTranceMan

    I remember around 15 years ago reading an article on a researcher (UK, I think) who proposed that the idea of panspermia wasn’t far-fetched, rather, it was likely. He used weak E.M. currents/fields interacting with various chemical vapors under varying conditions and found that the more abundant elements and compounds that exist in the dusty environs of a birthing stellar system almost always form complex organic molecules.

    As for life on Mars, it would be silly to suggest that there isn’t life there. If not native, surely as hitchhikers aboard the many exploratory craft that humans have sent there.

    As a side-note, Vegas bookmakers no longer accept bets for life on Mars. They will only let you lay money on a bet that there is no life on Mars…

  26. Quiet Desperation

    Quatermass and the Pit

    The giant Martian hologram at the end scared the holy living crap out of me when I was a little kid. It didn’t help that I was in the midst of a relatively bad flu, drifting in and out of fever dreams, and watching at night in a dark room.

    http://www.horror-wood.com/pit_qu6.jpg

    http://www.nigelkneale.cwc.net/qap20.JPG

    Good, old fashioned nightmare fuel as they said on MST3K. :)

  27. Gareth

    I hope Panspermia is incorrect! It’s hard enough trying to prove that life originated here on Earth – one tiny blue-green speck in the near-infiniteness of the cosmos. If we have to prove it originated *somewhere* out in the universe, then how are we ever going to know the initial conditions?

  28. Daniel Snyder

    I apologize that my first post here is a nitpick, but…the paragraph that starts “The researcher made models…” Is that measurement at the end of the paragraph supposed to be Pascals, or ATM? Because the way it’s written now, it looks like cyanobacteria are nigh invulnerable.

    I was talking about the origin of life yesterday in my geology class, and only made passing reference to organic molecules coming from outer space. The problem with panspermia is that, at some point, you have to bridge the gap between the living and the non-living anyway. If life originated on Mars, then there had to have been some kind of suitable environment there. If it originated far out in space, same dealy-o. We have to answer the question of where is it possible for life to originate, then start working on the question of where it did.

  29. American Voyager

    Okay, I’m going to approach this from the other angle. After that Martian meteorite sparked such a stir back in the 90s about possible Martian life (which I don’t agree with) it got me to wondering. We know that this planet is teaming with life and that we are hit. What are the odds that when we finally get to Mars and discover some evidence of present/past life that it won’t have ultimately come from Earth? Maybe the Martians are terrestrial………………..

  30. It’s an interesting idea, but I have a hard time believing that the origin of life on earth came from Mars. First, it the likelihood of this scenario occurring seems very low to me. And second, if life was capable of snapping into existence on mars, then it would be just as likely to snap into existence on earth without needing assistance from another planet.

    I do agree that this is an interesting concept, and begs the question, what if life on Mars was started from some other place? And if so, where? Makes for some great sci-fi possibilities!

  31. Yoshi_3up

    That’s going to be basically the intro of the game “Spore”, from the creators of The Sims, Sim City, etc. Life begins with the panspermia.

  32. Nigel Depledge

    Hmm, yes:

    “There are those who believe that life here started out there…”

    [nitpick]
    The BA said:
    “. . . the isotope ratios of the chemicals in the meteorites matches . . .”

    I think you’ve got a subject-verb agreement issue there, Phil. And you a professional writer, too. *tsk*.
    [/nitpick]

    ;-)

    WRT life on Mars, I think there will be a big challenge – if the putative life on Mars resembles Terrestrial life, how can we conclusively distinguish it from Terrestrial contamination?

  33. Daniel Snyder left a comment here?!?! Forget his thoughts on the origins of life. I’d rather hear him justify his decision to hire an unknown to be head coach of the Redskins.

  34. By the way, what’s the Battlestar Galactica reference? Did Starbuck once own a small Martian meteorite that fell out of his pocket or something?

  35. Charles

    “Radiation has been cited as a limiting factor in commode-spermia, however. If it were embedded deep within a rock or comet, it would be more likely to survive a trip.”

    Jim: you should read the Apollo 12 mission report. They landed near Surveyor III and brought back a piece of it. Before Surveyer was launched, it was not sterilized. One of the tests was to see if biological materials could survive the rigor of outer space, and in fact, some did survive the 31 months that Surveyor III had been on the lunar surface.

    Bacteria were found on only one sample, and some argue that the sample was cross-contaminated after its return to Earth. That argument holds less water upon deep analysis of the experimental protocol of both the Apollo mission and the methods used by the Lunar Receiving Lab.

    Maybe Phil can speak more to this, but I don’t know of any similar experiments since then, but the A12 results strongly suggest that bacteria are far tougher than we think and that they may indeed be able to survive outer space.

  36. Al

    Chris Reed got it ‘way back in post 2 …

  37. Panspermia is an interesting concept. Stephen Baxter touches on it near the end of his excellent novel, “Evolution.” (Have you read it, Phil?) But even if panspermia exists as a mechanism by which life gets from one world to the next, ultimately it comes back down to WHERE and HOW that life originally began. As for life on Earth, I think it’s likely that it began here, where conditions were right for carbon, hydrogen, oxygen, and nitrogen to gradually organize into increasingly complex forms.

  38. Mike

    “There are those who believe that life here began out there, far across the universe, with tribes of humans who may have…” and so one. It was the opening naration for the orignal Battlestar Galactica. Also a few people referenced that in the new one. I know Adama did in the mini series, to justify looking for Earth.

    “SO SAY WE ALL!!”

  39. Tobin Dax

    Gah! Maybe I shouldn’t read Phil’s blog during breakfast. I nearly choked when I saw that picture. It’s too funny.

  40. Hoonser

    God lives in space, God created the earth, therefore life was seeded from outer space. Case CLOSED!

  41. jess tauber

    What about life arising in the solar nebula? Before radiation gets really nasty (assuming nearby supernovae or high energy UV, winds, etc. haven’t already made life impossible) – where water can exist in different states, and hug dust, even link dust particles through weak forces to create a kind of muddy slurry, temperatures still low before stellar fusion or even full formation of planets. Lots of mixing of various blobs, huge surface areas and access to ‘metal’ ions, energy sources, etc.. Later freezing/mineralizing into place preventing destruction as final planetary/solar formation completes. Sort of an ‘Integral Cheese’ scenario…

    Finally they weather out after arrival on a survivable planetary surface. Or wait for meteorite collectors…..

  42. sudopod

    http://dailykos.com/storyonly/2008/2/27/71536/7689/2/464761

    Heads up, Doc! You’re mentioned on the front page of DailyKos today in an article about anti-global warming tards misinterpreting climate data.

    FYI ;)

  43. Linda DeMorrow

    I love the idea of panspermia. Since I’m not a scientist and only work with them, I come across a lot of pretty far-out ideas like this and love them all. Hope you’ll let us know when your book comes out and it’s title.

  44. Ken G

    Another issue that I don’t think gets enough attention is how often life originates but is snuffed out. There is kind of an assumption that as soon as you get anything that is identifiable as life, it is automatic that it will spread to every niche on the planet, and now to every other planet as well. Is there really evidence for this? Or is it possible that the first million things you might identify as being alive died out before they spread? And is one of the reasons they die out, competition with other life that started in some other niche and invaded the new one?

    If the latter, then we should not look for an “initial cause”, but rather we should see the whole solar system as a vast number of different spawning grounds, all coexisting and competing, all trying to create life that survives. If one takes that view, why would life that originates on Mars have a survival edge on Earth? Note the “head start” picture holds less water if life is constantly starting and dieing out.

  45. Ah, Chris Reed’s comment… I thought it was Balthazar who did the voiceover for the original BSG. It was McNee? Wow. OK, I withdraw my earlier comment and give Chris the FTW award.

  46. TheBlackCat

    Another sci-fi reference was Space: Above and Beyond. I only saw a few episodes, but one I remember has the aliens humans are fighting trying to broker a cease-fire. They inform the humans that based on amino acid comparisons that they evolved from single-celled organisms that originated on Earth and were carried to their world by a meteor (if I am remembering correctly). A meteor actually being able to get that far in a reasonable amount of time is negligible but it does reverse the normal pattern of these sorts of things.

    A nitpick: lichens are not bacteria. They are formed by a symbiotic relationship between a single-celled fungus and a single-celled algae, both eukaryotes. They sometimes have bacteria replace or help in addition to the eukaryote algae, but they always contain the fungus component.

    What I want to see is a panspermia story based on tardigrades (water bears), a group of microscopic arthropods. They can survive sustained pressures of thousands of atmospheres as well as a hard vacuum, can survive at few degrees above absolute zero for a short period of time as well as water well above boiling. They can survive radiation thousands of time higher than any other animal and can go without food and water for over a century. They can survive extremely high and low salinity as well as a wide variety of poisons. They are the only known animal that can be photographed under an electron miscroscope and survive the ordeal (it involves sticking then in a vacuum and then bombarding them with electrons).

    @ Daniel
    According to the paper it is atmospheres (they measure in GPa but BA’s conversion looks right to me).

  47. What’s more, tardigrades look cuddly, like little six-limbed teddy bears.

  48. flynjack

    Jeff Fite- Good speculation. To quote another movie “life finds a way”. The fusion crust on smaller chondritic meteroites only penetrates a few mm leaving the rest of the rock in pretty good shape. Cosmic ray bombardment of the rock traveling through space might be sporadic enough to alow something to make the trip if its short enough. No doubt that virus’s could tough it out even longer than bacteria.

    Ulitmately I think that life will develope given adequate conditions and enough time. Most recent info published pushed lifes existence on earth back to 4.0 billion years ago, a short 500 million years after earths initial formation. There was a lot of meteor bombardment going on at that time. Is it coincidence that life came about at the peak of the cosmic bombardment? Panspermia as a possible means of seeding cannot be ruled out yet, and thus has a place in the scientific debate.

  49. CarlosF

    The concept sounds interesting, but does not solve the question: How does life start? (and don’t get me started with the “what is life?” thing…).

    As a cool twist, if panspermia turns out to be true, that would take the concept of evolution to a different level. With all the variety of life forms on this planet, wouldn’t be cool to come up with some sort of “galacic evoultionary tree”?

  50. db

    BA said “It doesn’t say that the buggers could survive the trip here (millions of years)”.

    Millions of years might be the expected time. I wonder what the best case could be? What’s the fastest that a chunk of rock thrown up by an impact could make it from Mars to Earth, assuming best case planetary positions and rock trajectory?

    It might cut down the radiation exposure significantly…

    If you’re trying to calculate the best option for getting life from Mars to Earth you’d have to limit the cases to those for which the initial impact is survivable by the bacteria. No near-c extra-solar objects plowing through Mars and making a bee-line for Earth (unless you think a near-c collision would be survivable…)

  51. SkepticTim

    As I recall, Fred Hoyle was an ardent advocate of panspermia: this was one of the reasons he lost credibility (unjustifiably I think) within the scientific community.

    The idea of a Martian origin for life on earth is interesting but, as has been pointed out, only displaces the problem of its ultimate origin. Perhaps the claimed discovery of glycine (the simplest amino acid,: “… Snyder and Yi-Jehng Kuan of the National Taiwan Normal University say they really have found glycine. “We’re more confident [this time],” says Kuan. “We have strong evidence that glycine exists in interstellar space…” (2002) in giant molecular clouds is even more exciting – if this discovery has since been confirmed by other people. If the interstellar medium can synthesize glycine, can it also create more complex compounds?

  52. Sailor

    Well maybe it was a bit more complex – like the impact of a metor itself creating a chemical reaction that started some form of life. Since the the earth is made up of junk from space, whether it started there or here it does not seem to make a big dfference.

    As far as not “contaminating” other planets – I say lets go try and contaminat them. We the only one we know where life is for sure – no harm in kick starting it on a few neighbours for when we destroy this one.

  53. Daniel V

    Panspermia is a fascinating concept.
    Of course, if the phenomena exists, it doesn’t answer any questions about the origins of life, it merely pushes the question back a step.

    Speaking of which, is anyone kept awake at night by the huge scientific progress of infinite regress?

    Anyhow, an interesting concept, and the studies into panspermia have certainly yielded interesting results – for instance, we now know just how damn hardy some microorganisms can be in terms of their tolerances to pressures.

    I’d be willing to bet that Robert Zubrin of the Mars Society would love to be an emissary to Mars to test some of these panspermia/second genesis possibilities – so would I.

    If only human visits to Mars could happen within my lifetime… *sighs*

  54. Daniel V

    Sorry, in my previous post, I meant to say the “huge scientific PROBLEM of infinite regress”, not progress!

  55. Hi Phil. I’ve been following Gerda Horneck et al’s work during the last 5 years. It’s pretty neat stuff. Here is more information in case anyone here are interested.

    If one looks up references by Mark J. Burchell and Gerda Horneck on NASA ADS: http://adsabs.harvard.edu/abstract_service.html then they find quite a lot of published studies. For example:

    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004MNRAS.352.1273B&db_key=AST&data_type=HTML&format=&high=438d7c522923799

    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004IJAsB…3…73B&db_key=AST&data_type=HTML&format=&high=438d7c522923799

    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003OLEB…33…53B&db_key=AST&data_type=HTML&format=&high=438d7c522923799

    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001Icar..154..545B&db_key=AST&data_type=HTML&format=&high=438d7c522923799

    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005M%26PSA..40.5048S&db_key=AST&data_type=HTML&format=&high=438d7c522924702

    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004cosp.meet.2596M&db_key=AST&data_type=HTML&format=&high=438d7c522924702

    And this quote is important, where she says:

    [begin quote]
    Viable transfer from one planet to another requires that life, probably of microbial nature, survives the following three steps: 1) the escape process, i.e. ejection into space, e.g. caused by a large impact on the parent planet; (ii) the journey through space, i.e. time scales in space comparable with those experienced by the Martian meteorites (approximately 1-15 Ma); and (iii) the landing process, i.e. non-destructive deposition of the biological material on another planet.
    [end quote]

    There is a large range of conditions to test for these three steps. Many aspects look feasible. The traveling time in space of the Martian meteorites spans years to millions ot years, so that to me is one of the largest questions, whether they can survive that long of vacuum space conditions.

    See the chapter: Viable Transfer of Microorganisms in the Solar System and Beyond by Gerda Horneck, et al. in _Astrobiology: The Quest for the Conditions of Life_ by Springer 2002.

    It is an extremely comprehensive report, detailing the conditions that they have tested bacteria and the conditions that they still need to test.

  56. Torbjörn Larsson, OM

    Mars is smaller and farther from the Sun, so therefore it cooled faster than Earth did after the period of heavy asteroid and comet bombardment a billion or so years after the planets formed.

    Hmm. My uninformed understanding of what drives the likelihood for panspermia up was the short minimum period of time between the late heavy bombardment and the first signs of life, 100 – 200 My or so, not the cooling difference. Either life is really easy to start (yay!), or there was panspermia at low probability from comets as Wickramasinghe thinks (ouch!).

    But would DNA-based life really be proof that it had the same origin, or just evidence that DNA-based life is a typical channel for life to develop?

    DNA has a high degree of freedom to choose genetic code (i.e which codons codes for which amino acid). So seeing the same code would argue for the former.

    But IMHO the later scenario is already doubtful, as it is fairly verified that DNA is a secondary development. (Single stranded RNA is simpler; RNA can substitute for proteins; RNA substitutes for amino acid chains at the core of old structures as ribosomes.) And there is speculation in a number of alternative possible chemistries that could substitute for it.

    As far as abbreviations for units, we used to argue about that at my last job. Was it 10 Newtons or 10 newtons.

    Why argue, when it is an international standard? That is how Mars probes misses their targets.

    [anal] It is neither. It is 10 newton. The unit is singular, while the plural get absorbed into the quantity. (This simplification also makes tables and software easier.)

    The unit is lower case to distinguish from the person it is named for. However, the symbol is upper case to denote the person. I.e. 10 newton = 10 N.

    It is easier to remember the prefix rule: upper case for prefixes over unity (except k = 1000, to make the kg base unit follow the unit case rule), lower case for below.

    So it is 1 000 000 m = 1 Mm, while 0.001 m = 1 mm. [/anal]

  57. Torbjörn Larsson, OM

    DNA has a high degree of freedom to choose genetic code

    Oops. Of course I meant DNA machinery here. DNA by itself specifies nada.

  58. Torbjörn Larsson, OM

    @ flynjack:

    Most recent info published pushed lifes existence on earth back to 4.0 billion years ago,

    Do you happen to have a reference? I would be interested in such data, as I have only seen referenced numbers placing evidence at ~ 3.85 Ga, IIRC with error bars 100 – 200 My between it and the heavy bombardment dating.

  59. Katrina Cain

    I have a problem with Hoonser’s comment. A logical syllogism, it is not… I am willing to give them that they can use “god exists”, although I am a firm athiest myself, but if god exists, does he really live in the vacuum of space?
    Secondly, with regards to faith, I find that idea absolutely TERRIFYING that Scientologists could be onto something.. :)

  60. Jeff Fite

    Let’s remember, too, that Hoyle’s conception of panspermia (nudge, nudge) was that life existed everywhere in the universe for an infinite amount of time, and that the Earth was still subject to the influx of organic material and life-forms, including the annually-appearing new strains of influenza.

    This feat of belief was required because Dr. Hoyle rejected the idea that the universe had a finite beginning. In fact, he was the one who coined the term “big bang” in an attempt to discredit the new theory by ridicule.

    ‘Panspermia,’ in the sense of microbial life being widespread within our solar system, is a completely different matter.

    What we are discussing is science, because it is possible to test it.

  61. Evolving Squid, I’d love to hear your thoughts.

    My thoughts are relatively straightforward on abiogenesis.

    The universe is huge, and that’s just the part that we can see. There is a lot of matter, in what amounts to an infinite variety of permutations and combinations. The universe also has time on its side. Over time, all the permutations and combinations can be tried, and there are probably less of them than it might seem – elements and molecules can only interact in certain ways.

    The building blocks of life can mix at random in multiple places simultaneously all over the universe. Occasionally some stick together in just the right way to become the progenitors of what we call life.

    I neither think life is rare (on a universal scale), nor special (cosmologically speaking). It happens. Philosophically, I consider it to be the ultimate arrogance to presume that humans are somehow special in the grand scheme of things.

    Of course, we can’t see the whole universe, we can only see what’s nearby. We could, for example, be the only instance of a planet with life on it in our galaxy. Maybe there’s only 1 in Andromeda too. Maybe just 1 in every galaxy… that’s still a LOT of life.

    So, to sum it up, I think life started by chance. It’s starting by chance somewhere right now even as I type this (no, I don’t mean someone getting lucky tonight). And it’s dying off somewhere right now too.

    I’m not sure that tells you what you wanted to know, but it is 0130, and I should get to bed soon :)

  62. Chip

    >>>>>ThoughtCriminalon wrote: “Another fictional reference from “Quatermass and the Pit” (1967): We are the Martians.”<<<<<

    Another favorite line from that film is: (With rising anger.)
    “Do you mean to tell me that we owe our human condition to the intervention of insects!?”

    Quartermass: (Calmly, earnestly.)
    “Yes. I do.”

  63. Don’t know about clouds of E. coli in outer space, but Uranus is probably full of them.

  64. SkepticTim writes:

    [[As I recall, Fred Hoyle was an ardent advocate of panspermia: this was one of the reasons he lost credibility (unjustifiably I think) within the scientific community. ]]

    He lost it because he embraced concepts that were cool and provocative rather than because there was adequate evidence behind them. He believed the Big Bang couldn’t be true because it was “religious,” that abiogenesis was impossible because of a combinatorial problem (creationists love to cite his “airplance in a junkyard” analogy), and that interstellar dust consisted of bacteria. He had to keep adding epicycles to keep his version of Steady-State cosmology viable, and he just didn’t seem to get that if theory A and theory B both explain the same stuff, but theory B is ten times more complicated than theory A, it’s logical to go with A.

  65. Squid writes:

    [[Philosophically, I consider it to be the ultimate arrogance to presume that humans are somehow special in the grand scheme of things.]]

    Ignore whether it’s arrogant or humble. Is it true or false? And how do you know?

  66. SkepticTim

    Barton Paul Levenson;

    I agree that Hoyle did promote some rather odd speculations; he seemed to enjoy throwing out arbitrary concepts just to provoke ‘spirited’ disputation: and he was rather too attached to his (and Bondi’s, if I remember correctly) steady state universe. However, Hoyle also made some very worthwhile contributions.

  67. Tom Marking

    Since it hasn’t been mentioned here I thought I would bring up a different theory for the origin of life which is being espoused by Thomas Gold in his 1999 book “The Deep Hot Biosphere”. In that model life did not orginate at the surface of our planet, but rather at great depth – perhaps up to 5 km deep or more. Only later did it expand to the surface of our planet.

    If this is the case, then it holds out hope for life on other planets such as Mars because the conditions between Earth and Mars (or any other terrestrial planet) at a depth of 5 km are much more similar than the conditions at the surface. Therefore, the question of which planetary body originated life may not be so meaningful after all. It may be that they all did but only certain planets had suitable conditions at the surface for life to migrate outward.

    Anyway, here’s a URL discussing the idea in case anyone is interested:

    http://www.wired.com/wired/archive/8.07/gold_pr.html

  68. Steve Boltzman

    http://www.liebertonline.com/doi/pdfplus/10.1089/ast.2007.0134

    “Microbial Rock Inhabitants Survive Hypervelocity Impacts on Mars-Like Host Planets [and] The results support concepts of viable impact ejections from Mars-like planets and the possibility of reseeding early Earth”

    “Impacts on Mars-Like Host Planets [and]…ejections from Mars-like planets and…reseeding early Earth”

    Round-trip to Mars “lithopanspermia?” Utterly improbable.

    In the early Solar System? …Multiplicity without necessity.

    After a future cosmic cataclysm? Gee, where did the time go, Sol?

    All of “panspermia” is pre-evolutionary wishful-thinking nonsense.

  69. Ira

    I agree Panspermia from Mars is highly improbable! Only slightly more possible than Panspermia from other solar systems and galaxies, given the awsome distances and time periods seeds of life would have to survive in the harsh environments of space.

    However, Directed Panspermia, as proposed by Crick and Orgel, where the seeds of life may have been purposely spread by an advanced extraterrestrial civilization is certainly possible.

    An advanced civilization may adopt Directed Panspermia as an “insurance policy” against the chance of self-destruction or natural disasters. They might launch multiple spaceships with frozen or vitrified biological cells along with robot operated genetic engineering labs and a complete genome record as well as details to reconstruct their civilization on similar planets in other solar systems and galaxies.

    Famed cosmmologist Stephen Hawking has urged that we spread into space to save human life and civilization from probable destruction here on Earth. He gives us less than a thousand years. This theme is developed in novel form in 2052-The Hawking Plan.

  70. I have real problems with panspermia.

    It seems to me unlikely that bugs originating somewhere else, very, very different in conditions, would enjoy it here as much as they evidently do.

    Earth is evidently very life-friendly and has been for 3.5 billion years at least. Why could life not originate here?

    As a last issue, I have doubts about the space-faring super-bugs. Yes, we have bacteria living in hot springs, flourishing in rocks at high pressures, and able to withstand hard radiation. However, it seems to me likely that they didn’t _start_ like that, springing into existence fully formed. I seems reasonable that naked DNA or RNA is likely the first replicator from which we are descended, and DNA is a pretty fragile molecule, held together only by hydrogen bonding. I would think the warm stagnant rockpool would be a more likely place for such material to survive and proliferate, rather than a black gusher.

    Only once the first replicator survives and begins to reproduce can natural selection start to produce endoplasm, tough cell walls, cilia, etc., etc., and begin to colonise more and more niches. Modern bacteria are pretty sophisticated and evolved life forms – including the toughies.

  71. John

    I beleive it. I belive that there is life, some where out there, beyond our solar system.

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