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Scientists Study Trajectories of Life-Bearing Earth Meteorites

Posted by samzenpus on 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.'"

18 of 199 comments (clear)

  1. Panspermia by The+Evil+Atheist · · Score: 5, Insightful

    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.

    --
    Those who do not learn from commit history are doomed to regress it.
    1. Re:Panspermia by olsmeister · · Score: 5, Insightful

      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.

    2. Re:Panspermia by fatphil · · Score: 5, Interesting

      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.

      --
      Also FatPhil on SoylentNews, id 863
    3. Re:Panspermia by socialleech · · Score: 5, Informative

      You should read about the Miller-Urey experiment.

      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?

    4. Re:Panspermia by ArcherB · · Score: 3, Insightful

      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.

      --
      There is no "I disagree" mod for a reason. Flamebait, Troll, and Overrated are not substitutes.
    5. Re:Panspermia by mcgrew · · Score: 3, Insightful

      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.

      --
      Free Martian Whores!
    6. Re:Panspermia by Migraineman · · Score: 4, Interesting

      I guess he just threw a rock to see what would happen at some point.

      So your version of God isn't all-knowing and all-powerful? I'm not buying that a God who is capable of creating billions of planets, stars, and systems wouldn't have a firm grasp on probability and interstellar trajectories. Maybe we should consider that your God is bored (he does control everything, right?) and has set up the universe as a giant Rube Goldberg machine for His entertainment. He would have to accede to non-interference for the exercise to have any value.

    7. Re:Panspermia by paleo2002 · · Score: 3, Insightful

      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?

  2. that's depressing by circletimessquare · · Score: 5, Funny

    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?

    --
    intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
  3. Sub 1cm Ejecta by RivenAleem · · Score: 4, Interesting

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

  4. Worth a read, but ... by Trapezium+Artist · · Score: 5, Interesting

    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.

  5. Re:Place Bets Here by jochem_m · · Score: 4, Insightful

    and the fact that it's more like hitting any of a dozen cockroaches with a million needles...

  6. Tasty aliens... by mevets · · Score: 3

    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.

  7. You are exceptional by exploder · · Score: 5, Insightful

    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.

    --
    Yo dawg, I heard you like the Ackermann function, so OH GOD OH GOD OH GOD
  8. Martin Lo's low energy trajectories by mattr · · Score: 4, Informative

    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
    http://genesismission.jpl.nasa.gov/gm2/team/people/lo/interview1.htm

  9. simple math, brought to you by Google Calculator by Lluc · · Score: 3, Interesting

    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

  10. Re:Don't you mean... by Anonymous Coward · · Score: 5, Insightful

    Just once I'd like to see an origin-of-life article on Slashdot without atheists dragging religion into the discussion.

  11. Re-entry may not be that challenging by onyxruby · · Score: 3, Interesting

    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

    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.