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Earth Space Science

Scientists Study Trajectories of Life-Bearing Earth Meteorites 199

Posted by samzenpus
from the we-come-from-earth dept.
Hugh Pickens writes "About 65 million years ago, Earth was struck by an asteroid some 10 km in diameter with a mass of well over a trillion tonnes that created megatsunamis, global wildfires ignited by giant clouds of superheated ash, and the mass extinction of land-based life on Earth. Now astrobiologists have begun to study a less well known consequence: the ejection of billions of tons of life-bearing rocks and water into space that has made its way not just to other planets but other solar systems as well. Calculations by Tetsuya Hara and his colleagues at Kyoto Sangyo University in Japan show that a surprisingly large amount of life-bearing material ended up not on the Moon and Mars, as might be expected, but the Jovian moon Europa and the Saturnian moon Enceladus also received tons of life-bearing rock from earth. Even more amazingly, calculations suggest that most Earth ejecta ended up in interstellar space and some has probably already arrived at Earth-like exoplanets orbiting other stars. Hara estimates that about a thousand Earth-rocks from this event would have made the trip to Gliese 581, a red dwarf some 20 light years away that is thought to have a super-Earth orbiting at the edge of the habitable zone, taking about a million years to reach its destination. Of course, nobody knows if microbes can survive that kind of journey or even the shorter trips to Europa and Enceladus. But Hara says that if microbes can survive that kind of journey, they ought to flourish on a super-Earth in the habitable zone (PDF). 'If we consider the possibility that the fragmented ejecta (smaller than 1cm) are accreted to comets and other icy bodies, then buried fertile material could make the interstellar journey throughout the Galaxy,' writes Hara. 'Under these circumstances fragments could continue the interstellar journey and Earth origin meteorites could be transferred to Gl 581 system. If we take it as viable, we should consider the panspermia theories more seriously.'"
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Scientists Study Trajectories of Life-Bearing Earth Meteorites

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  • Panspermia (Score:5, Insightful)

    by The Evil Atheist (2484676) on Thursday April 12, 2012 @08:20AM (#39656131) Homepage

    If we take it is viable, we should consider the panspermia theories more seriously.

    Only as a possible answer to the origin of Earth's life. It still doesn't answer the origin of life itself, wherever it may have started.

    • Re:Panspermia (Score:5, Insightful)

      by olsmeister (1488789) on Thursday April 12, 2012 @08:39AM (#39656239)
      No, but it could answer the question of how life managed to arise here on earth in a relatively short period of time, and would also exponentially expand the potential area we consider when we think about places that could have been suitable, both chemically and environmentally.
      • by kanweg (771128)

        When you throw a dice, your first throw may be a six. Why are you trying to do statistics with a single event?

        Bert

        • by SQLGuru (980662)

          When you throw a dice, your first throw may be a six. Why are you trying to do statistics with a single event?

          "God does not play dice with the universe."

    • Re:Panspermia (Score:5, Interesting)

      by fatphil (181876) on Thursday April 12, 2012 @08:41AM (#39656261) Homepage
      I've seen arguments on a scientific mailing list in the last few days that this paper is based on false assumptions. It has assumed (too high) values for masses based on (too low) values for velocities based on the assuption that the meteorites are aiming at earth under its gravity, rather than aiming for the sun under its gravity and accidentally hitting earth on its way towards the sun.

      If you change the masses downwards to what they should be, then the chance of them getting through an atmosphere without breaking/burning up and denaturing all its alleged payload become minuscule.
    • God? (Ducks!)

      I still follow the premise that Life originated on earth. As a random chemical reaction, that created simple DNA strains that that happened in an area where the environment stayed constant enough for those chemical reactions to persist but changing enough to allow the strain to change over time. The Chemical Reaction that didn't break down allowed for more chemicals to connect to the DNA strand and multiply.
      • Re:Panspermia (Score:4, Insightful)

        by ArcherB (796902) on Thursday April 12, 2012 @09:07AM (#39656501) Journal

        God? (Ducks!)

        I still follow the premise that Life originated on earth. As a random chemical reaction, that created simple DNA strains that that happened in an area where the environment stayed constant enough for those chemical reactions to persist but changing enough to allow the strain to change over time. The Chemical Reaction that didn't break down allowed for more chemicals to connect to the DNA strand and multiply.

        While thinking about it, the environment would not necessarily need to change to force the DNA to change (evolve). All the "environment" needs is to be stable enough to foster replication. The edges of such an area would provide the change in conditions needed for evolution to take hold. The bonds that were able to multiply at the edges and beyond did so. Those that were not able to didn't.

        An example would be ocean vents. This environment is rather stable and fosters life within it. Along the edges, where the conditions are not as favorable to the original life forms, most those that are venturing out will die. Those that don't die continue to reproduce, each surviving generation better able to survive further away from the vents until the need for the vents completely disappears.

        Just my $0.02 and I'm not a biologist. But I have stayed in a Holiday Inn and the concepts are not that hard to grasp.

        • Re:Panspermia (Score:4, Insightful)

          by mcgrew (92797) * on Thursday April 12, 2012 @09:20AM (#39656609) Homepage Journal

          From what I've read (which was a LONG time ago so further discoveries and theories may have developed), Earth had little or no oxygen when life developed, and the oxygen would have been a poisonous byproduct, like methane is to today's life.

          So life itself would have changed the environment, of course along with other such variables as volcanos, continental drifting, and meteors.

        • All the "environment" needs is to be stable enough to foster replication.

          Its the bit between "dumb chemicals" and "things actually replicating" where we're a bit wobbly. If a stable environment were all it took we could have recreated the process many times.

          • by cusco (717999)
            I'm left assuming you have a couple hundred million years to let your experiment run, then? Good grief, I can set up a wireless mesh network and let it run and connectivity will be perfect for years until that moment that a train is going past, the janitor is running the vacuum with the bad motor brushes, and a tractor-trailer rig is parked in the fire lane simultaneously. If you wait long enough pretty much anything combination of things that CAN happen WILL happen, good or bad. The Urey-Miller experime
      • by Chris Burke (6130)

        God? (Ducks!)

        Indeed -- not God, but Ducks! Some might say they're one in the same (especially the ducks). And given ducks' well-known sexual proclivities, a theory of panspermia where basically every object in the galactic vicinity, even those with no chance of the payload taking root, being "inseminated", makes a lot of sense.

      • It wouldn't have been DNA; DNA is too complicated and has problems replicating without a bunch of machinery. RNA is one possibility, though I personally have the feel that it is too complicated as well. One example of a hypothesed simpler pathway is Cairn-Smith's Clay hypothesis (http://en.wikipedia.org/wiki/Abiogenesis#Clay_hypothesis) though experiments indicate that clay crystals likely aren't stable enough to work for this purpose. However, there only needs to be some kind of material with the right

    • Re:Panspermia (Score:5, Informative)

      by socialleech (1696888) on Thursday April 12, 2012 @08:54AM (#39656383)
      You should read about the Miller-Urey experiment [wikipedia.org].

      For those to lazy to read about it, scientists have created all of the amino acids required by life, using nothing but inorganic compounds, by recreating the atmospheric conditions of early Earth.

      Life may or may not have originated on Earth, but we tested it and found that it could have. If it could have been created here, using nothing but the things that the universe placed here, why couldn't it have also developed else where? Are we the seeding planet of the galaxy/universe? Were we seeded? Or is life just incredibly common?
      • Re: (Score:2, Informative)

        by Anonymous Coward

        You're not still dragging out that tired old experiment, are you? Have you figured out how many orders of magnitude (both in terms of probability and complexity) bare amino acids are away from the simplest self-replicating thing we have found on earth so far? You'll need a lot more experimental evidence than just Miller-Urey to bridge the gap between inorganic compounds and life.

        (Yes, there are experiments that show self-replication of specially-designed ad hoc molecules, but the experimenters have to pro

        • Re:Panspermia (Score:4, Insightful)

          by paleo2002 (1079697) on Thursday April 12, 2012 @10:23AM (#39657407)
          When comparing panspermia to a terrestrial origin for life people seem not to fully comprehend one important factor: time.

          It began raining on the Earth about 4-4.4 billion years ago, meaning surface temperatures and atmospheric conditions were stable enough for the oceans to accumulate. Some of the earliest evidence of biochemical alteration of the atmosphere (banded iron formations) first appear about 3.7 billion years ago. That's over 500 million years for naturally occurring amino acids to jump to self-replication and then to simple prokaryotes. Now, think about the rate at which microorganisms reproduce. 500Ma is about as much time as its taken for life to jump from single-celled forms to modern vertebrates, etc.

          Panspermia includes too many unknown and slim chances. And, as mentioned elsewhere in these posts, where are these life-seeding bolides coming from?
          • by symbolset (646467) *

            where are these life-seeding bolides coming from?

            Did you know that all of the elements on Earth heavier than iron were once inside a star? It's true - and not our star, either.

          • Amino acids don't self replicate. That's what DNA (or RNA) is for. However, your primary point is still valid. Time allows nature to futz around until something works. 500 million years is a long time. A very long time.

            • Also any chemist knows that you always get a little of an unlikely reaction product if your original volume is big enough, or you mix things for long enough. You only need to make a self-replicator (or just a vaguely catalytic) product once.

          • by geekoid (135745)

            Other planets.

            You can have both.
            Hell, Human beings could be wiped out by a giant piece of rock from a destroy planed, and organic compound on that rock could eventually become the new life forms.

        • by Chris Burke (6130)

          Of course Miller-Urey is pretty irrelevant now that we've found amino acids floating in clouds in space. They're everywhere.

          Anyway, so we're accepting that spontaneous assembly of self-replicating molecules is possible in principle, but appealing to the low probability of the right conditions appearing. Well, billions of years of constant change due to geologic activity and countless deep-ocean vents of varying compositions, plus the fact that we're here, suggests that while the probability may be low, th

          • by geekoid (135745)

            No it isn't. It shows that amino acids can come from inorganic compounds. Being on Earth isn't needed.

            • by Chris Burke (6130)

              No it isn't. It shows that amino acids can come from inorganic compounds. Being on Earth isn't needed.

              Sorry, what are you saying? We've discovered amino acids all over the place in space. The experiment showing that amino acids can arise naturally is thus largely redundant with the direct observation of naturally occurring amino acids.

        • How many orders of magnitude? Ok, let's say that the odds of those amino acids forming a self replicating 'thing' are 1000000000000 less likely than the formation of the amino acids themselves. It took Miller-Urem 1 gallon of water and 1 week of time to produce virtual every amino acid required for life. Now instead of a gallon, you have the entire surface area of the Earth's oceans at the time. And instead of a week you have millions, if necessary billions of years. Every time someone talks about ho

          • by cusco (717999)
            I've seen several recent articles speculating on below-ground sites as being possible locations for abiogenesis. Some clays form a convenient 'scaffold' for amino acids to line up, and also happen to promote the creation of lipid bubbles. Energy sources are abundant and varied underground, and chemicals migrate only slowly, giving time for multiple reactions to happen. Also, the sheer volume means innumerable possible appropriate locations.
    • If we take it is viable, we should consider the panspermia theories more seriously.

      Only as a possible answer to the origin of Earth's life. It still doesn't answer the origin of life itself, wherever it may have started.

      So you mean mom was right - you are evil alien spawn?

    • by tinkerton (199273)

      I'll offer a view that goes the other way round, that of the irrelevance of panspermia. Life originated on earth because under the right conditions that is inevitable. Incoming meteorites with life or predecessors of life wouldn't have made any difference. Life on other planets is hard. Incoming seeds originating from earth wouldn't make any difference.

      If you look at the origins of panspermia theories however, they're of the silly kind: "life is very difficult to start so it must have come from elsewhere".

  • humanoids walking on two feet with funny heads

  • so the culmination of mankind's civilization, scientific efforts, and technological achievements, is to go to some exoplanet, only to find some foot fungus some dinosaur had long before mankind ever appeared?

  • Place Bets Here (Score:3, Interesting)

    by flyneye (84093) on Thursday April 12, 2012 @08:27AM (#39656175) Homepage

    Hmmm, made it to other Earth-like planets instead of randomly catching a closer strong gravitational field or drifting randomly into nothingness.
    Even making Europa would be kind of like hitting a cockroach with a needle from across a football stadium.
    Oh to be the house, if this scientist ever landed in Vegas with a wallet-load... Sounds like someone needs to re-fill the ol' grant jar.

    • Apparently you've forgotten about gravity.

      • Re:Place Bets Here (Score:4, Insightful)

        by jochem_m (1718280) on Thursday April 12, 2012 @08:40AM (#39656249)
        and the fact that it's more like hitting any of a dozen cockroaches with a million needles...
        • by flyneye (84093)

          To add to my Vegas theme, consider the planets are moving like a roulette wheel. Further consider that gravity could also act as a slingshot rather than a mitt, dependent on distance from the modifying source it approaches. The numbers of the odds just roll like cherries, bells and bars on a slot machine, the more criteria you add.

      • by flyneye (84093)

        Which gravity? The Suns? Are you assuming the ejecta came out in a general direction available to magically put it under the weak gravitational field of planets and moons so distant it would be like trying to get a BB to stick to a magnet by throwing it across the stadium? Did you not take into account how many directions are available that do not line up with the motions of our Suns hub of planets and asteroids? If it went in an upwards direction relative to our position around the sun, even nearby gravit

        • You do realize the solar system is not necessarily aligning its orbital plane with the galactic orbital plane, and that the volume of the galaxy around it's orbital plane is enormous?

          Something going "up" isn't heading out of the galaxy necessarily. In fact, unless it achieves galactic escape velocity, or falls into a conduit of unusual gravity interactions, then it's going to be orbit in and be captured by something, somewhere, eventually.

          • by flyneye (84093)

            Then how many degrees of direction did stuff go, how did it disperse the further it got, how much useful material will fall in a useful place at what stage of development and potential for survival of the place then to find the time needed and then to have potential to rise above any other "geo- sperm" from " competing" sources. The more I think about this the more I get like Hawking about contacting aliens. There are just so many things that seem to work against this, I'm not seeing odds I can live with y

        • by cusco (717999)
          You need to read up on the dynamics of space flight, and take a look at the sheer volume of material ejected. You are aware that there are quite a number of rocks from Mars and the Moon here on Earth, aren't you?
          • by flyneye (84093)

            I'm thinking of all that and considering the sheer volume of null targets and trajectories that are more likely even in the face of gravity if you consider the wide splatter trajectory. Then there's the other thought that there might be an ejection of something a bit more chunky and less dispersed and what could keep it from finding a chance trajectory that would take it to a viable planet and still be able to make it to evolved life in this amount of time.
            Not sure how well rocks evolve or if they hold enou

    • by exploder (196936) on Thursday April 12, 2012 @09:34AM (#39656745) Homepage

      Astounding! With just a few minutes of thought and your superior intuition, you've dismissed the result of careful calculation and decades of training on the part of this group of scientists. Imagine what a genius of your magnitude could accomplish from within the scientific system...it truly staggers my humble intellect! But I'm sure you're working on much more important things.

      • by flyneye (84093)

        Noticing that the king wears no clothes is one thing, and not appropriate, but yes, I question the absence of his codpiece.
        Now if you have any information about the physical absence of his genetalic cover, I would appreciate some of this insight your fanboys have endowed you with.

        • by ceoyoyo (59147)

          You're just a trash tabloid staff editorialist unless you actually read the paper and comment intelligently on their methods. I suppose you might get some play on the National Enquirer... I mean Slashdot, but that doesn't make you clever or insightful.

          • by flyneye (84093)

            I really wish I could get all you guys to see all the posts, this has potential for a fun conversation if you increase your perspective.
            Relax, grab a beer( unless it's too early there) and let's think about this.
            I'd say it would even be a treat if we all skimmed some of it, had our little thread thingy, made our "BETS" as implied originally, then go back for some research from our perspective.
              I bet you give gifts unwrapped, don't you?

            • by ceoyoyo (59147)

              Sorry, you've lost me. I read the whole thread. I was following your "emperor has no clothes" metaphor. What is it we're thinking about? Your vague assertion that "even making Europa would be kind of like hitting a cockroach with a needle from across a football stadium" followed by some silliness about Vegas and grants?

              • by flyneye (84093)

                It actually started with Vegas,grants and cockroaches in the stadium.
                Odds, think odds and the criteria it takes to get it there.

    • by Chris Burke (6130)

      Even making Europa would be kind of like hitting a cockroach with a needle from across a football stadium.

      True. Now explode a pile of trillions of needles and see if any one of them hit the cockroach.

      Oh to be the house, if this scientist ever landed in Vegas with a wallet-load...

      If the bet was that any of the visitors to Vegas would win the slot machine jackpot, the house might not be as willing to make the wager as you.

      Of course they'd only make that decision after doing what this scientist did, and actually calculating the expected pay-out. Estimating probabilities by gut feel isn't going to make you a winner in Vegas, even if you are the house.

      • by flyneye (84093)

        I dunno about a trillion. Let's add that to the mix though.
        If it were that means the ejecta really splattered like Gallaghers melon in a lot of directions, but also that smaller amounts went with each "packet". perhaps a few "needles"were icy raindrops and hit. Then you face odds of survival. How's earthlife going to do as an ice chunk of earth water or frozen mudball on the surface of an icy moon? Of course the odds of these raindrops (which are still dispersing further from each other, the further they tr

    • by mattr (78516) <mattr AT telebody DOT com> on Thursday April 12, 2012 @10:11AM (#39657255) Homepage Journal

      Actually Martin Lo discovered low energy gravitational paths or "superhighways" that would allow objects like space probes and maybe rocks to travel all around the solar system without power. These calculations were used in the Genesis probe NASA project IIRC.
      http://en.wikipedia.org/wiki/Interplanetary_Transport_Network [wikipedia.org]
      http://genesismission.jpl.nasa.gov/gm2/team/people/lo/interview1.htm [nasa.gov]

      • by flyneye (84093)

        Now that's a consideration too, another spin of the wheel in space-Vegas.
        Might an x % or even all of this be stuck on some pan-galactic Nascar track to nowhere?
        I wish I could get all you guys to see each others posts and ideas to add to the odds, it would make this thread a blast!

      • by flyneye (84093)

        And yes that increases the odds of it hitting something in our system, acknowledged. But the value of icy chunks landing on an icy surface with our homegrown life starts then being able to evolve usefully in this amount of time is in question. The Mars thing would be cool and it would give some "Enquirer prestige " to some Russian Scientist rumoured to have seen a "scorpion" like thingamadoo on a Venus pic. (lol, maybe that was the Enquirer someone told me about)

    • by onyxruby (118189)

      More like hitting a cockroach with a needle from across a football stadium, and you have millions of needles being launched at speeds well high enough to leave orbit. And then every so often you fire your needle cannon again and again.

      To put this in perspective, all you have to do is look at the moon. The chances of any given spot on the moon being hit by an impact are incredibly small, so small they are astronomical. However when you look at the moon, you can see the entire thing is covered with impact cra

      • by flyneye (84093)

        O.K. this has come up in this thread and this is a better example of the space highway thing. Thank you.
        This spins the odds back down to something a bit more in grasp, but the viability/distance/dillution thing vs. finding a suitable planet in a suitable age of development is still giving me pause. Although the enormity of time does help a bit.
        Good one.
        I wish slashdot would implement a feature where we could explode any parent and its children so the group could see the conversation and we could bounce idea

        • by onyxruby (118189)

          I don't think you were trolling, which I think some of the other posters may have assumed. In essence, I'm conceding your point that for any given piece of debris to make it to a given location is absurdly low, even by astronomical standards. Certainly the odds are so bad that the bet probably would not be legal is Las Vegas.

          The thing that makes this paper viable though is that I don't have one piece of debris or just one shot. A large impact like the one that wiped out the dinosaurs could make millions of

          • by flyneye (84093)

            Give this man a cigar!
            That brings us closer to fruition than any post yet.
            I still have reservations about timeline and possibility of reaching somewhere that bacteria could eventually work up to legs and cable television, but now I would at least drop a small bet on the table, just in case.

          • by flyneye (84093)

            It could be too that most usually take my cynicism for trolling, but I am fairly jolly today and it has some bearing.

            I still think the /. system could benefit from including some advanced thread abilities to facilitate group oriented discussion in a round table style. Checking messages doesn't always show whats going on elsewhere in the thread.

  • Sub 1cm Ejecta (Score:5, Interesting)

    by RivenAleem (1590553) on Thursday April 12, 2012 @08:27AM (#39656177)

    How do objects this size survive the trip through the destination planet's atmosphere?

    • by ceoyoyo (59147)

      Some of them are big enough, others hitch a ride on comets or asteroids.

      There are pieces of Mars littering Earth. It happens.

  • by SJHillman (1966756) on Thursday April 12, 2012 @08:28AM (#39656183)

    There are those who believe that life out there began here
    Flung far across the universe, before there were tribes of humans...

  • by Trapezium Artist (919330) on Thursday April 12, 2012 @08:30AM (#39656205)

    I've made a quick scan of the underlying academic article by Hara et al., along with one of my colleagues in a meeting here, who is closely involved in the issue of planetary protection (i.e. making sure that our spacecraft don't "pollute" the solar system bodies they fly to and land on).

    Of course, this is a known issue in general: after all, there are meteorites on Earth which we know came from Mars, so the converse is obviously possible. But extending this to moons of Jupiter, Kuiper Belt objects, and even exoplanetary systems, and finding that a significant number of Earth rocks may have been dumped there is interesting. So, the article is worth a more careful read.

    However, my antennae were sent into a state of high agitation when I saw that the article has been posted on the arXiV following its having been accepted to the infamous Journal of Cosmology. We've discussed that here before: I invite you to view the journal website (easily found by googling) and decide for yourselves how reputable it is.

    Which raises the question of why Hara et al. chose to publish there. That I can't answer, obviously, but will keep it firmly in mind as I read the paper in more detail.

    • Which raises the question of why Hara et al. chose to publish there. That I can't answer, obviously, but will keep it firmly in mind as I read the paper in more detail.

      Because it's rather long on speculation and short on facts?

      And because there's no way to test any of this for a very long time to come?

      • Well, in principle the paper is a fairly simple series of mathematical equations which you could actually work out on the back of an envelope. The devil though is in the details, namely the numerical parameters input to those equations. While many of those are straightforward and well-known, some may enter that category of WAGs (wild-assed guesses), and it's quite possible that the equations are particularly sensitive to (some of) those. That's why it's worth reading, to try and figure out where the issues

  • by mevets (322601) on Thursday April 12, 2012 @08:50AM (#39656343)

    If we share common ancestry, that means we might find alien life tasty and nutritious. ... to seek out new life and new civilizations, to eat.

    • To Serve Man, anyone?

    • Panspermia seems like it would make for a good handwave in science fiction why humans could find edible food on an alien planet, or have to worry about alien diseases. I have a hard time believing life could actually spread from planet to planet this way. But I'm not a physicist or biologist.

    • But, whoever develops interstellar travel first will no doubt have the technological edge to be the taster and not the tastee. Why was E.T.'s belly so big and were Reese's Pieces a favorite garnish?

  • So, without realizing it, we're ALREADY colonizing our galaxy. Life bearing rocks from earth hit other planets, those planets also experience trauma sooner or later, ejecting their rocks into space millions of years later, after life had caught on, and so on and so on.

    Therefore, Earth may be a colony of some other civilization from billions of years ago, or, we're creating colonies as we speak.

  • I could believe that some simple life form could suvive on a rock travelling through space for millions of years, but I don't see how it would have survived the heat of the impact event that blasted it beyond escape velocity in the first place

    (at least life as we know it, Jim)

    • by ceoyoyo (59147)

      Most non-dinosaur killing meteorites land cold.

    • by symbolset (646467) *
      Myriad wonders the universe has. Bacteria that live two miles beneath the surface of the Earth. Bacteria that subsist on an energy cycle of direct heat conversion. Natural Fission Reactors [wikipedia.org] that can provide energy for such bacteria for billions of years. Frost in interstellar space that condenses on the outside of anything passing through to impossible thickness. Supernovae that blast their planets to smithereens, spreading them across the galaxy.
  • How can we study the trajectory when we don't know:

    When the asteroid hit?

    The earth's position relative to the sun, the other planet, and the rest of the stars in the galaxy at the time of impact.

    The direction from which the asteroid hit us.

    The size of the asteroid.

    For starters....

  • Panspermia is a very interesting/compelling theory. But I'd avoid telling anyone in academia that you're interested in an Earth genesis hypothesis other than evolution.
    You may just as well have told them that you're a pro-lifer, who voted for Bush, are home schooling your kids, believe in a balanced budget, and are a racist all in one sentence.

    • by blueg3 (192743)

      Evolution isn't an origin-of-life theory. You're thinking of abiogenesis.

    • by Hatta (162192)

      I'd avoid telling anyone in academia that you think evolution is an "Earth genesis hypothesis".

    • Oh bullshit. Panspermia has been around for decades and lots of mainline scientists (including Francis Crick, one it's earliest proponents) have thought it interesting.

      But it is more entertainment than anything else - until we get off planet enough to test it. A dozen probes to Mars and a Europa would be good start, but as always - if you've got the money, I've got the time....

  • by Lluc (703772) on Thursday April 12, 2012 @10:25AM (#39657429)
    Assume we're just dealing with Carbon (molecular weight 12) here, and "well over 1 trillion tonnes" is actually 2 trillion tonnes:

    number of molecules per gram = (Avogadro's Number) / 12 grams = 5.02E25 molecules/kg
    2 trillion tonnes = 2E15 kg
    (5.02E25 molecules / kg * 2E15 kg) = 1.004E41 molecules

    Surface area of sphere with radius of 20 light years = 4.499E35 meters^2

    1.004E41 molecules / 4.499 meters^2 = 223,091 molecules / meter^2 == 4.44 attograms of carbon per square meter.
    This is a pretty thin layer of material to survive reentry on some 20 light year distant planet.

    --------
    Alternatively, from google: ((Avogadro's number / (12 grams)) * (2 trillion tonnes)) / (4 * pi * ((20 lightyears)^2)) = 0.223099739 kilometers per liter = 0.5 miles/US gallon, which means we totally need to collect some gas guzzler tax on this material
    • by ceoyoyo (59147)

      Fortunately rocks aren't light. Their atoms tend to stay clumped together instead of spreading out uniformly like photons.

  • by onyxruby (118189) <onyxruby@@@comcast...net> on Thursday April 12, 2012 @01:31PM (#39660727)

    Just a thought here, but I don't think re-entry would be that challenging for bacteria based life to survive. Most people think that what left of an asteroid is really hot when they land, but that just isn't the case. In fact asteroids have been touched right after landing and described as 'cool' in temperature.

    http://impact.arc.nasa.gov/news_detail.cfm?ID=1 [nasa.gov]

    If bacteria were in the core part of the asteroid that survived impact it should be reasonable to assume that the part that is cool to the touch never got hot enough to kill any bacteria that were inside it. The other two questions than become what kind of shock (g-forces) can bacteria survive? We know they can survive the shock of being launched into space, and without the squishy bodies that we have they may well survive the shock of re-entry.

    If we could determine the answers to those questions than really the only questions remaining are can bacteria adapt to their new home? We already know they live in places on earth that are very inhospitable by our standards. The only other real question is how long can they survive in space? We have documented cases of bacteria surviving in space for years at a time. If there is no real limit to how long they can survive in space than cross solar system colonization is all but inevitable.

I judge a religion as being good or bad based on whether its adherents become better people as a result of practicing it. - Joe Mullally, computer salesman

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