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The best thing about writing fiction is that you get to make stuffup. And when the fiction you're writing is science fiction,you don't even have to obey the laws of biology, physics orcommon sense. Want to have a Stay Puft Marshmallow Man go to warwith a couple of crazed Transformers? Have at it. Director Ridley Scott takes full advantage of this license in hisnew blockbuster Prometheus and never more so than in the opening scene. Scientists have alot of theories about exactly when in Earth's history lifefirst emerged and precisely where and how it occurred. But you canbe pretty sure no one's suggested that it happened when anaked alien landed on the planet, drank a fantastical potion andthen threw up into the nearby waterways, seeding a virginal Earthwith his DNA. A few million years and a few jillion specialeffects later, human beings venture into space, meet ourprogenitor race and discover that, yes, we're the aliensafter all. (If you've already seen the film, you'llenjoy TIME's attempt to answer all the Big Prometheus Questions ) O.K., so maybe this wasn't peer-reviewed by the NationalAcademy of Sciences. Still, it's not a fully crazy idea.Indeed, it's one scientists have explored in a far moremeasured way than Scott for a long time. Panspermia is the wonderfully descriptive name for the idea thatlife or at least the precursors of life may be common in theuniverse and that for many planets, including Earth, biology didnot just arise de novo. Rather, it was imported aboard incomingmeteorites, comets or asteroids. There's a wonderfully visualquality to this idea, as science illustrators discover when theypaint an image of a life-carrying comet striking a sterile Earthand come up with something that looks like a sperm cell fertilizingan egg. Of course, simple imagery, no matter how serendipitouslysatisfying, has no bearing on whether the theory has anythingbehind it, but multiple studies over the years have backed it up. ( MORE: TIME's Complete Prometheus Coverage ) Astronomers have long believed that while water appears to beubiquitous in the universe, it was not terribly common on theboiling rock that was the primordial Earth. Incoming comets which are mostly rock and water ice might have solved thatproblem, colliding with the planet, hydrating its surface andeventually filling its oceans and seas. A 2011 study gave greater weight to this idea, showing that the ratio of heavyto light water aboard Comet Hartley 2 is a lot closer to the ratioin earthly water than we ever knew, making it likelier that ouroceans were indeed filled up from afar. Water, of course, isa sine qua non for life as we know it, so even if there wasnothing pre-organic aboard any incoming comets, they still helpedget the planet biologically started. But organics are out theretoo. In 1969, for example, a 220 lb. (100 kg) meteorite landed inAustralia, lighting up the night sky and crashing to the ground inthe town of Murchison. Promptly dubbed the Murchison Meteorite, itwas found to have been geologically altered in a way that suggestedits home world wherever it was had plenty of water. Much moreimportant, the rock turned out to be rich in amino acids, whichserve as building blocks of proteins and peptides. Not everyone was sold on the idea that the acids wereextraterrestrial in origin, mostly because the meteorite lay on theground long enough to have been contaminated by earthly chemistrybefore it was found. In 1979, however, investigators found a pairof meteorite fragments in Antarctica that had landed about 200,000years earlier, and these too carried amino acids. The permafrost ofthe South Pole region is not a place likely to contain biologicalcontaminants, and the researchers thus concluded that the aminoacids were authentically extraterrestrial. Over the years, the case for the cosmos as a biological incubatorhas only grown. Amino acids have been found in interstellar clouds a fact that is true of water too. Of the 20 amino acids thatexist on Earth, eight have been detected in meteorites. Tellingly,while amino acids can form in either a left-handed or right-handedconfiguration essentially mirror images of each other life onEarth uses just the left variety. And of the eight acids brought inby meteorites, only one glycine is a righty. Biologists havenever been able to explain why earthly life prefers left-handedamino acids, since both types should work equally well. The answermay be that they are simply the kind that happened to rain down onus, and we used what we got. The case for E.T.-as-biological-dad got even more compelling lastyear, when geologist and mineralogist Christopher Herd from theUniversity of Alberta analyzed a meteorite that landed in British Columbia's LakeTagish in 2000 and found that it contained amino acids and other organiccompounds and that the rock had been continuing to cook them up asit flew through space. The materials were present in the meteoritein five different stages of their development, progressing fromsimpler to more sophisticated states. Herd believes that traces ofwater in the matrix of the rock, coupled with heat fromgravitational accretion and radioactive elements, allowed themeteorite to serve as a kind of flying incubator. "It could have operated almost like a hydrothermal cell, withwater circulating through the asteroid," he said."After a while, the heat would run out and that process wouldshut off, and you'd be left with different stages of organicmaterials." ( MORE: How to Weigh an Asteroid and Why You Should Care ) While we'll never know the worlds on which the organics thatmay have given rise to us originated, it's possible that onevery familiar planet is responsible: Mars. It's not that hardfor the Red Planet to hurl the occasional rock at us. An asteroidstrike would send Martian debris into space, which would slowlyspiral in until it was snared by the gravity field of Earth. Asrecently as last July, 15 lb. (7 kg) of Mars rock landed in Africa,making a total of 240 lb. (110 kg) of Martian material that hasbeen collected over the years. It's the chemical makeup ofboth the rock itself and the traces of Martian atmosphere capturedin it that pegs its origin, as well as the fact that the rocks arecomparatively young millions of years old, compared with thebillions of years that asteroids have been around. This suggeststhat they come from a geologically active place, which also fitsthe Martian profile. It was on Aug. 6, 1996, that the most famous Martian rock of all made headlines . NASA announced that a meteorite known as ALH84001 that had landedin the Antarctic in 1984 appeared to contain microscopic fossils ofMartian bacteria in the form of tiny carbon shells. That was, byrights, stop-the-presses stuff, and the midday news conference atwhich NASA announced the findings made global headlines. "Today rock 84001 speaks to us across all those billions ofyears and millions of miles," said then President BillClinton. "It speaks of the possibility of life. If thisdiscovery is confirmed, it will surely be one of the most stunninginsights into our universe that science has ever uncovered." Alas, the discovery wasn't confirmed. Too many otherexplanations and unresolved questions poked holes in the thrillingtheory: the globules could have been formed volcanically; they weretoo small to have contained RNA; they could have been the result ofearthly contamination. In recent years, the rock has picked up morebelievers, and some scientists have concluded that if theannouncement that Martians had been found was too breathless, thebacklash against it was too pitiless. Either way, findings from theMartian rovers Spirit and Opportunity have confirmed that Mars wasindeed once a very wet and perhaps fecund place, and while neitherof those Mars cars confirmed the existence biology, the newCuriosity rover that will land this summer on the 16thanniversary of the 84001 announcement, as it happens could wellturn up something. None of this means that human beings carry so much as a scrap ofextraterrestrial organics, or if we do, that it's any morethan a meaningless soup on of exobiology in an otherwisedomestically grown breed. What it does mean is that in its ownsilly, sweeping, cinematic way, Prometheus is right: our remote little world, sealed in by the film of itsatmosphere, will always be part of the much larger universe itsphysics, beauty and biology included. LIST: The 10 Greatest Movies of the Millennium (Thus Far). The e-commerce company in China offers quality products such as China Portable Battery Power Packs , Laptop Battery Refill, and more. For more , please visit Universal Power Adaptor For Laptops today!
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