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Chicxulub Impact Might Have Spread Life-Bearing Rocks Through the Solar System 161

KentuckyFC writes "Some 65 million years ago, an asteroid the size of a small city hit the Yucatan Peninsula in what is now Mexico, devastating Earth and triggering the sequence of events that wiped out the dinosaurs. This impact ejected 70 billion kg of Earth rock into space. To carry life around the Solar System, astrobiologists say these rocks must have stayed cool, less than 100 degrees C, and must also be big, more than 3 metres in diameter to protect organisms from radiation in space. Now they have calculated that 20,000 kilograms of this Earth ejecta must have reached Europa, including at least one or two potentially life-bearing rocks. And they say similar amounts must have reached other water-rich moons such as Callisto and Titan. Their conclusion is that if we find life on the moons around Saturn and Jupiter, it could well date from the time of the dinosaurs (or indeed from other similar impacts)."
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Chicxulub Impact Might Have Spread Life-Bearing Rocks Through the Solar System

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  • And Vise-Versa (Score:5, Interesting)

    by Press2ToContinue ( 2424598 ) * on Monday November 18, 2013 @04:23PM (#45457313)

    A nice example of panspermia.

    • Re:And Vise-Versa (Score:5, Insightful)

      by MightyMartian ( 840721 ) on Monday November 18, 2013 @04:29PM (#45457357) Journal

      A nice example of how panspermia might happen. It's a helluva leap between having life-bearing rocks blasted off of earth by a massive meteor collision, and quite another to suggest that the rest of the solar system could have been seeded.

      • Seconded.
        That's a really long trip to be taking in the life-unfriendly vacuum.
        And at the end you land pretty hard on something no quite like where you grew up.
        Liquid water? Check!
        Photosynthesis? Hope you brought it with you!
        Other food? Not Mexican!
        Gases? See above.

        • Re:And Vise-Versa (Score:4, Informative)

          by ShanghaiBill ( 739463 ) on Monday November 18, 2013 @05:03PM (#45457705)

          Liquid water? Check!

          Maybe not. Europa is believed to have an ice layer between 10 and 30 km thick []. It is unlikely that an impact by a 3m rock would penetrate more than 100m or so. The impact would melt some water, but it would quickly refreeze. Europa's surface is pocked with craters millions of years old, so there does not appear to be a regular turnover of the ice that would carry any surviving life to the ocean below.

          • Re:And Vise-Versa (Score:5, Insightful)

            by Charliemopps ( 1157495 ) on Monday November 18, 2013 @05:29PM (#45457967)

            Europa has liquid water geysers, and fissures that routinely open up and then re-freeze. Think of the top layer of ice as our earths crust and the (possible) liquid ocean beneath like our liquid rock core. The surface ice shifts constantly and allows briney water to escape to the surface before it re-freezes.

            Now, what are the chances that a microbe laden rock would land in one of these crevasses? Pretty low, but keep in mind it's frozen, and could remain frozen on the surface for a very long time waiting for a crack to open beneath it. The odds are still pretty low I admit, but then keep in mind that these large collisions, microbe laden asteroids and Europa's ice flows have been going on for billions of years. Even if the odds per event are almost nil, the cumulative effect is staggering.

            When I think of space, I find it hard to believe anything is "impossible" given the vastness and near timelessness of it all. Granted there are some universal physical laws (speed of light) that make some things impossible. But anything that is simply "very very unlikely" has probably already happened.

            • Re:And Vise-Versa (Score:5, Informative)

              by Samantha Wright ( 1324923 ) on Monday November 18, 2013 @06:40PM (#45458665) Homepage Journal
              It's pretty problematic that the impact in question happened in Mexico. The Yucatan isn't exactly a haven of extremophiles—you wouldn't expect to find anything that can maintain a biosphere without a good light source, and they're definitely not well-adapted to the sulphur and magnesium contamination [] that Europa appears to have. Unfortunately the best places to find organisms with a chance of surviving in this kind of environment are at the bottom of the ocean, which is a particularly bad target for producing ejecta. Caves are also a possibility, and since Mexico has no shortage of them, they might be a potential avenue... but who knows if there were any decent ones in the Yucatan at the time.
              • Re:And Vise-Versa (Score:5, Informative)

                by ShanghaiBill ( 739463 ) on Monday November 18, 2013 @08:19PM (#45459371)

                The Yucatan isn't exactly a haven of extremophiles

                There are extremophiles everywhere if you go deep enough. Endoliths [] (organisms that live inside rocks) have been found at depths of 3 km, and probably commonly live even deeper. Endoliths can endure temperatures of 120C (250F), and have also been found in the extreme cold and low humidity of the Dry Valleys of Antarctica []. If anything can survive the journey to Europa, it is probably an Endolith.

                • I was thinking that might be the trick, although the region is still not very suitable for honing and maintaining cold-weather survival skills. Here's hoping the crater was pretty deep.
              • The Yucatan isn't exactly a haven of extremophiles

                Whom were ancestors of the extremophiles? Only other extremophiles, or have they sprang forth from more nominal relatives? When I consider that getting trapped under a glacier has caused live to live with little or no oxygen (blood falls []), I often wonder just how hard it is to become an extremeophile? Perhaps the extremophiles really aren't so extreme after all? Perhaps every environment can be seen as extreme depending on your point of view.

                I mean, here on earth we have life using a sulfate catalyst

                • Hold your horses: that shit takes significant amounts of time. Unless there were snow-topped mountains in the Yucatan, there was no ice to acclimatize to. It's easy to adapt to periodic ice—even if every single bacterium gets wiped out one year, new bacteria can still enter from the outside environment each year until an antifreeze protein is developed and a foothold established.

                  The more extreme the new conditions, the harder life has to work to adapt. As it is, there are only a handful of bacteria (e []

          • Re:And Vise-Versa (Score:4, Insightful)

            by hubie ( 108345 ) on Monday November 18, 2013 @05:34PM (#45458023)

            This is addressed in the paper. The paper abstract:

            Material from the surface of a planet can be ejected into space by a large impact, and could carry primitive life forms with it. We performed n-body simulations of such ejecta to determine where in the Solar System rock from Earth and Mars may end up. We find that, in addition to frequent transfer of material among the terrestrial planets, transfer of material from Earth and Mars to the moons of Jupiter and Saturn is also possible, but rare. We expect that such transfer is most likely during the Late Heavy Bombardment or during the next one or two billion years. At this time, the icy moons were warmer and likely had little or no icy shell to prevent meteorites from reaching their liquid interiors. We also note significant rates of re-impact in the first million years after ejection. This could re-seed life on a planet after partial or complete sterilization by a large impact, which would aid the survival of early life during the Late Heavy Bombardment.

        • by mmell ( 832646 ) on Monday November 18, 2013 @05:31PM (#45457989)
          Yon organic matter needn't survive, reproduce and grow - it only needs to introduce the kind of complex organic molecules (amino acids, protiens, etc.) which form the foundation of evolutionary life on this planet. Hell, all the microbes in question (be there one or one million) can die on impact as long as their protiens/nucleic acids etc. remain (even partially) intact. Planetery physics will take care of the rest.

          Just don't expect anything familiar to evolve out there.

          • by Sique ( 173459 )
            Hm... Madagascar is separated from any other land mass since 150 mio years, and the evolution there, while quite different than in Africa, with almost all species being endemic, is not that different from other continents and islands. There are no different orders of species there, just families and genera are different (and endemic). I don't expect an evolution which lasted only 65 mio years, less than half that of Madagascar, to be radically different.
            • by mmell ( 832646 )
              Madagascar is nonetheless subjected to roughly the same atmospheric, radiation, and physical environment as the rest of the Earth (magnetic fields, chemicals, gravitic variations due to the presence of a single large satellite in orbit, tides, etc.). Liquid water is present at the surface, temperatures hover between roughly 275-305K. Atmospheric pressure tends to be something like 1 atmosphere (plus or minus a miniscule fraction).

              Just sayin'.

              • by Sique ( 173459 )
                If it is much colder (as on Europa or Titan), then the van't Hoff rule just lets us expect the evolution being much slower (about 2-3 times per 10 degrees).
                • But changing rates changes evolutionary pressures and therefore morphology and organization. So, there may well be other effects than a stochastic slowing process.

                  Overall, life is going to be constrained by the physics of the organizing molecules - proteins and sugars can only do so much. Other chemistries are certainly possible, but we've yet to see them work.

                • Admit it... You're just REEEEEALLY hoping for space lemurs.
                  • by Sique ( 173459 )
                    No. I just don't expect anything.

                    Panspermia is some idea that pops up here and there, but I guess it totally misses the point.

                    • Organic compounds can form in abionic environments. So the null hypothesis should always be: Organic matter has formed where we found it.
                    • Organic compounds are quite sensitive to high temperatures and get destroyed easily. Most of them burn or at least denaturate. Complex molecules are much more sensitive. A meteor impact will destroy almost all organic compounds but the simplest
            • While I will agree that 65 million years is not long in geological time, any novel life forms trying to develop on Earth have to compete for limited resources with existing organisms that are already well-adapted to their environments. It is probably much less likely for some alternative to cellular life as we know it to develop here in parallel with existing life than it is somewhere that we seed a supply of proteins and amino acids and watch to see what happens.
      • A nice example of how panspermia might happen. It's a helluva leap between having life-bearing rocks blasted off of earth by a massive meteor collision, and quite another to suggest that the rest of the solar system could have been seeded.

        It is a much, much, much, bigger leap to suggest that such impacts could lead to the transfer of life between star systems. Panspermia [] usually refers to the hypothesis that life spread throughout the universe, not just between planets surrounding one sun.

        • Baby steps. Let's give it a few million miles before we start looking at light years and surviving interstellar space.

        • I believe that article has things upside down. My introduction to the concept of panspermia suggested that life originated in space, then was slowly introduced to planetary surfaces. The idea that life is spread by catastrophic impacts on planetary surfaces seems far less likely than simple space critters evolving after landing on a planet.

          • by hubie ( 108345 )

            From the first paragraph in their paper:

            Panspermia is the hypothesis that life can be spread between planets and planetary systems. One class of panspermia is lithopanspermia, in which pieces of rock are the mechanism for dispersal (Tobias & Todd, 1974; Melosh, 1988). Rock fragments can be ejected from an inhabited planet's surface via large meteor impact. This ejected material can then travel through space and may land on another planet or moon, as we have seen in identified meteorites from Mars found on Earth (Bogard & Johnson, 1983; Carr et al., 1985). If an ejected rock encases sufficiently resilient organisms, life could be seeded on its destination planet or moon.

          • Most panspermia proponents I've seen (of the Hoyle variety) seem to be a little shy on any specific details other than a sort of a Battlestar Galacta-esque "life here began out there" kind of line. There's no real substance to their "theory" beyond a "golly, it sure seems unlikely abiogenesis happened here, but somehow, someway, it's more likely somewhere else in the Local Group."

            Most of the what I woudl consider legitimate "xenobiologists" don't really look beyond the solar system. There are some that thin

        • Hm...

          Well, from the actual research paper...
          "They estimate that a rock of 3 m across shields D. radiodurans for 10 Myr, and 3.3 Myr for B. subtilis"

          10 million years is a loooong time. The simulations were calculating in the mere kiloyears according to the paper.

          Take oneof the higher ejection velocities... 12.41km/s - let's make it a nice round 10km/s.
          Aaaaand, pick a solar system near-ish to us, that is known, like 10.5 light years away. Call it 10^14 km away...

          That's a mere third of a million year transi

      • by Livius ( 318358 )


        But leaps happen.

      • Earth is still throwing rocks into space in modern times, a significant portion of what was once the island of Krakatoa is now in space. The force of the explosion is said to have shot rocks the size of houses into space.

        As for seeding the solar system I personally think it's possible but improbable due to the fact that when a space rock hits a planet or moon at that speed, it is instantly vaporised and then rains down on the surface as microscopic glass beads, if it survives that then it's certainly com
        • Earth is still throwing rocks into space in modern times, a significant portion of what was once the island of Krakatoa is now in space.

          Cite? Throwing rocks into space is one thing; throwing them so they don't come back is quite another. Absent an injection thruster that kicks in at the right height, the only way to prevent an object coming back down is to accelerate it to escape velocity. That's a tall order.

        • >it is instantly vaporised and then rains down on the surface as microscopic glass beads

          So no meteorites have landed on earth?

      • Re:And Vise-Versa (Score:5, Insightful)

        by symbolset ( 646467 ) * on Monday November 18, 2013 @06:42PM (#45458685) Journal

        Not really. Somebody computed the likelihood of Chicxulub material making its way to the nearest stars and found it not only a certainty, but they were able to estimate the total mass per neighboring star, the time en-route, and so on. In the roughly 3.5 billion years since life arose on Earth the sun has made 17 laps around the Milky Way. The Oort cloud is fairly well polluted with life. Sometimes a star comes a little too close, and we do some border trade on the frontier. Interstellar comets pass through every year gathering up a little bit on their lonely journey. Sometimes they run into things, and leave a little litter from what they've picked up on their road trip. Consider that the Milky Way had an 8 billion year head start on us, and the conclusion is obvious.

        Space is big. Really, really mind-bogglingly big. But time is also long.

    • Exactly - as life on earth may have been seeded from Mars, Venus, or....somewhere out there.
    • by SJHillman ( 1966756 ) on Monday November 18, 2013 @04:35PM (#45457437)

      There are those who believe...that life out there began here, far across the Solar System...with tribes of dinosaurs...who may have been the forefathers of the Europans...or the Callistians...or the Titans...

      Some believe that there may yet be descendants of microbes...who even now fight to survive—somewhere beyond the heavens!

      • Re:And Vise-Versa (Score:4, Interesting)

        by TapeCutter ( 624760 ) on Monday November 18, 2013 @07:35PM (#45459081) Journal

        There are those who believe...

        *The emperor rises to his full height slapping his testicles together in applause*

        Bravo Court Jester, another wonderfully funny and politically astute show. Your best show yet - if I may be so bold as to critique your art.

        *For the first time during the evening, the audience is silent, you can hear the tension in the air but nobody dares so much as a whisper*

        Let it be known to my court, there are some in the empire who take their sci-fi too literally and talk of the solar system as a real place where Europeans - or whatever they're called - exist.
        We must all take care not to confuse reality and fantasy in our daily conversations because such talk without the sharp comedic wit of a professional artist is a threat to our very survival. As we know it promotes the heinous crime of irrational thinking when it's is plain for all to see that there is nothing beyond the celestial ice dome but more celestial ice dome. What is it about "ice all the way up" that is so hard for some in my court to comprehend? Well I believe Octopus' razor tells the court that nobody is that reallystupid, the best mathematicians of the court are all convinced the stories are a sophisticated code for subversive activities of the court's enemies. They must be stopped or they will rip the court asunder!

        *Set to sinister music* - The emperor slowly withdraws back into his emerald green exoskeleton until only his four eyestalks are visible to the audience, all the while taking mental notes on those who are not enthusiastically applauding his own politically pointed performance.

    • It had to be called panspermia, not panovumia, right? Right.
  • by JoshuaZ ( 1134087 ) on Monday November 18, 2013 @04:24PM (#45457319) Homepage
    At this point, we have a pretty good understanding of using genetics to estimate roughly when two populations diverged. If we find such life, we can first test if it at all resembles Earth life. If it does (in the sense that it uses most of the same amino acids, and uses similar machinery for DNA and replicating DNA), then we should be able to get a rough estimate of when it separated from Earth life based on how genetically different it is. There will be some difficulty with this sort of technique, since the life on alien worlds may be subject to extreme selection pressures, but that should be something we can roughly account for.
  • by Anonymous Coward on Monday November 18, 2013 @04:30PM (#45457375)
    Dinosaurs were adapted very well of a N2 / O2 atmosphere and would not survive very well in the atmospheric mix of Europa or Titan, even if they did survive the journey there in their adult or larval stages. Aside from that, they need a very specific diet to survive that would not exist on any of the moons or planets they might find themselves on after re-entry. To the best of our knowledge, photosynthesis occurs on only a single body in the Solar System - Earth. We would be able to spot it's telltale signs if it occurred elsewhere.
    • Is that a bad attempt at a joke or did you just miss the obvious? The Earth was teeming with microbial life, some of which could quite possibly endure not just the trip but some of the conditions found elsewhere.

      • by ColdWetDog ( 752185 ) on Monday November 18, 2013 @05:06PM (#45457749) Homepage

        But I like the idea of a 'larval' T. Rex falling down on some foreign planet or moon and reproducing. Jurassic Park in Space?

        No, no Mr. Spielberg, that was a joke. Please don't do that. Don't write that down.

        • Well, no one is saying that the dinosaurs didn't have space travel.
        • It does explain Jar Jar Binks...
        • Well, science has shown that dino DNA in amber has degraded so much that it would be impossible to create a real Jurassic Park with it. However, DNA on a rock that flew into space and stayed at very low temperatures might give better results, right? So they could come up with a scenario in which a space ship flies to Titan, finds a rock containing dino DNA, incubates it into a real life T-rex on board the ship, etcetera. It will be unlike any movie ever done before!

    • I am pretty sure that the article was not referring to the rock being blasted out there with little baby dinosaurs hitching a ride, more like virii and bacterium, and other single celled organisms. but in typical /. fashion I did not RTFA so maybe im wrong and maybe they are talking about t rex and stegosaurus chillin on the moons of Jupiter
    • Re:Would not survive (Score:4, Interesting)

      by SJHillman ( 1966756 ) on Monday November 18, 2013 @04:41PM (#45457503)

      Fun fact: Evidence suggests that life was around on Earth for some 200 million years before photosynthesis; Even after the evolution of photosynthesis, it would have likely taken millions more years for it to change the atmosphere in any way detectable to visitors... nevermind distant observers. Although its presence may be a telltale sign of life, the absence of it shouldn't be taken as evidence of no life.

  • Watch out for Chiggie von Richthofen...
    • Watch out for Chiggie von Richthofen...

      He's unrelated. 65 million year old Mexican rocks are still traveling to his home world.

      That said, an amazingly good show for broadcast tv, of course it didn't last.

      • by mmell ( 832646 )
        Yup. Doomed to fail. It aired on FOX.
  • ...welcome our new Sleestak....

    Sorry, I can't go on.

  • by epyT-R ( 613989 ) on Monday November 18, 2013 @04:38PM (#45457461)

    At the point of impact, aren't we're talking millions of degrees of heat energy? Wouldn't this sterilize anything ejected from the planet?. This whole premise sounds more like a bad scifi movie than a real hypothesis.

    • by MozeeToby ( 1163751 ) on Monday November 18, 2013 @04:52PM (#45457579)

      Rock is a pretty good insulator and the impact would have thrown boulders from well away from ground zero. Basically, you've got a single shot Orion Drive [] with rock instead of a steal shield. You'd actually have a harder time keeping a rock cool on the way up and out than from heat directly from the blast; you'd have to leave the ground significantly above escape velocity to maintain that speed through a few dozen kilometers of atmosphere.

      • Just for the sake of argument - an impact that size, ejecting one or more huge fragments of the earth's crust, would necessarily rip the atmosphere apart pretty thoroughly as well. Smaller fragments of the earth's crust might follow behind a large fragment, travelling in a near vacuum. We could probably model some of those rocks escaping the atmosphere without being heated enough to be sterilized. I put this in the realm of possibility, but I don't put it high in the realm of probability.

      • Rocks burn up falling through atmosphere. Were talking about accelerating a rock upwards from the ground through the same air into space.
        • Objects heat up when they pass through air, period. The rate of heating depends on the air density and the relative speed -- it doesn't care a fig what direction the object is going.

        • Rocks burn up falling through atmosphere. Were talking about accelerating a rock upwards from the ground through the same air into space.

          Rocks burn up in the atmosphere because of the large delta-v between them and the earth. Something falling straight down as if dropped would not have this issue any more than the guy that jumped from space. Escape velocity for the Earth is 11 kms and 42 for the solar system. Unsure what that would look like but given the case, the sample in question would not be shot like out of a gun through atmosphere but likely pushed out by a pressure wave along with everything including the atmosphere around it at the

    • Not really.

      Asteroids hit the ground at about room temperature on the surface, and often below ambient temperature internally. Anything being blasted into orbit would experience similar temperature increases on the way out.

      The spot directly impacted would be heated considerably, but the crater would extend many miles beyond that. I find it entirely feasible that such "life-bearing" rocks could exist.

      What I find less likely are the odds of these rocks being blasted well out of Earth orbit, and impacting anoth

    • by c0lo ( 1497653 )

      At the point of impact, aren't we're talking millions of degrees of heat energy? Wouldn't this sterilize anything ejected from the planet?.

      Taking into account the speed of heat diffusion in the mass of the ejecta, it may happen that the surface may reach some thousands degrees without the core experiencing an increased temperature of more that some degrees. I'd say, within the realm of possible for a rock 3 meters in diameter, ejected at high speed into the near 0K of the space in a matter of seconds.

      (don't forget that the impact energy is not transferred in full to a small amount of rock, a big part of it is spent in dislocating those rock

  • by madmarcel ( 610409 ) on Monday November 18, 2013 @04:50PM (#45457559)
    For some reason I read that as:
    "Cthulhu Might Have Spread Life Through the Solar System"

    to which the answer is: Probably not.
  • by Jedi Holocron ( 225191 ) on Monday November 18, 2013 @04:54PM (#45457585) Homepage Journal

    ...polluting space for aeons...

    • Life is absurdly contagious.
    • This! There's so much junk in space it's like you don't have to worry if your ship breaks down. Find an old 1960's version of your broken part floating around (probably be within 10 feet of you) pop it in and your good to go.
  • by tverbeek ( 457094 ) on Monday November 18, 2013 @05:01PM (#45457685) Homepage
    The Sentinel is going to be pissed that we'd already contaminated Europa.
  • Land or land not; there is no attempt.

  • Imagining that all life must have originated from Earth is an amazingly earth-centric point of view that is similar to the idea in the middle ages that all planets must revolve around the Earth. Obviously, if life can travel from Earth to Europa, it can also travel from Europa to Earth...or from planets outside of our solar system entirely. Moreover, the fossil record shows the presence of life on a very early Earth, leaving far too little time for life to form in primordial Earth oceans under any sort o
    • by hubie ( 108345 )

      Imagining that all life must have originated from Earth is an amazingly earth-centric point of view

      This claim is not made anywhere in the paper, or anywhere else for that matter that I can find.

    • by Livius ( 318358 )

      They're saying this could have been an opportunity for life to migrate from Earth to Europa etc., not that it was the only possible way for there be life there.

    • by Hatta ( 162192 )

      leaving far too little time for life to form in primordial Earth oceans under any sort of process currently envisioned.

      While any of the individual chemical reactions required for abiogenesis would be exceedingly rare, you have to consider that they were taking place in parallel across the surface of the Earth. The Miller-Uray experiment ran for a week in a few small flasks. You can expect much less frequent reactions to happen, at least once, when you do the same thing in the entire volume of the oceans o

    • The real question is 'where did life originate in the universe?'

      The conservative answer would be: On the inside.
      A liberal answer would be: Anywhere shit has happened.
      Like any discovery, information, or idea: Life could have more than one independent origin.
      Ergo: All of our patents infringe extraterrestrial prior art.

  • Not that I would need any, as a card-carrying geek.

  • If it turns out to be true, that would be pretty cool.

    But I also hope they've made a better go of it than we have. Could hardly be worse, really.
  • Dinosaurs on Europa! We should go there, bring a couple of 'em back, and open a theme park! I'll call it "Jurassic Park XIV: The End of the World"!

  • Table 5 (Score:4, Informative)

    by ZombieBraintrust ( 1685608 ) on Monday November 18, 2013 @06:16PM (#45458431)
    The 20,000kg number is from Table 5 in the journal. I think the summary is a little deceptive.
    Probablilty of life bearing rock ejected from earth reaches Europa is: 2.8E-6 ± 5.0E-7 %
    Yeah thats .0000028% plus or minus .0000005%
    Including all rocks that were ejected they believe 6 plus or minus .9 rocks would reach Europa.
    The 20,000 Kg number comes from those 5 to 7 rocks.
    • by fatphil ( 181876 )
      Can't be arsed to work out solid angles in steradians, let's just do things in terms of area, as all that matters is the ratio.

      Area of the earth: 5*10^14 m^2
      Area of projection of Europa onto earth's surface: 5*10^2 m^2 ( )
      => Ratio of "out there" which is Europa: 10^-12.

      I would therefore claim that unless there's a bloody good reason for things to be 30000 times larger, the probability of ejecta reaching Europa should be more like 0.0000000001%

      And that presumes nothing in between us
      • by fatphil ( 181876 )
        OK, now I'll look at the paper....

        The simulation makes steps that are 1 day in granularity.
        They are simulating particles that are travelling 10km/s.
        Therefore one time step is 10^6 km.

        They are asserting that these objects that take million kilometer steps are intersecting with a 3000km target which is also moving a million kilometers per day (relative to jupiter, sometimes twice that, sometimes half that relative to the sun). I would suggest that they are grossly overestimating the probability of collision i
  • Scientists at Ioan Space Agency are laughing at earth for lobbing back a few rocks with primitive life forms in them back it Io. They point out that it originally the ejecta from Io that actually seeded the biology of Earth.
    • Scientists at Ioan Space Agency are laughing at earth for lobbing back a few rocks with primitive life forms in them back it Io.

      Thus, lo and beheld was the veracity of loan sharks.

  • The Moon side facing us (unlike the other side) is riddled with craters that may have appeared around that time (~-65My). A big chunk of the ejected rocks on Earth may simply have landed on the Moon.
  • ... to cross interstellar distances even at ridiculously low velocities. Something travelling at less than 100 m/s will travel over ten light years in 65 million years. Chunks from Earth might have ended up in the Alpha Centauri system by now.

    Btw, have we found any extrasolar debris in our star system? It might be like looking for a needle in a haystack, but I'm sure we could find some pieces of exoplanets right in our back yard.

Never worry about theory as long as the machinery does what it's supposed to do. -- R. A. Heinlein