[meteorite-list] Did Earth Seed Life Elsewhere in the Solar System?
If, in the Gladman simulation, 30 Earth rocks get to Titan in 5 million simulated years, that's 6 Earth rocks per million years. Over the life of the solar system, that's 27,000 microbe bearing Earth rocks for the Titan environment. Makes it sound like a favored holiday destination of Earthly microbes... Not so many years ago scientists told us that it was impossible for meteorites to deliver rocks from Mars to Earth, because they would be shock melted by the forces necessary to give them escape velocity. Now they seem to be falling over themselves with calculations that show Earth rocks pelting other bodies like crazy! I think it shows a little bit of wishful thinking, and also how fads can influence scientific research. Personally, I think they are vastly underestimating the difficulty of blasting coherent rocks thru Earth's atmosphere. More likely, when the forces are great enough to do it tektites are the result! In other words rocks are vaporized. A low angle impact has been cited as the easiest way to eject rocks from Mars, but this won't work on earth because of the atmosphere. Could a rock be entrained in the blast column so it could be ejected thru the vacuum column left by the asteroid's decent without being vaporized? Probably not, as the ones in the center of the blast would be vaporized, and ones at the edge of the column would be held back by contact with the earth's atmosphere. Is any of this testable? If rocks can be ejected from Earth, then there must be millions, to billions accumulated on the Moon's airless surface. Wouldn't some of them be incorporated in the Lunar regolith and then returned to Earth with the Apollo samples or meteorites we have found? If the sample size to date is too small, then we will have to wait for a permanent moon base. Sincerely, Mike Fowler Chicago __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Did Earth Seed Life Elsewhere in the Solar System?
Hi, Panspermia in reverse? Jeff Moore [says] Once one planet comes down with life, they all get it. Reminds me of a cartoon I saw over 20 years ago (and taped to my refrigerator until it fell apart) of an anthromorphised Mars saying to an anthromorphised Earth, I don't how to tell you this, but you've got some kind of parasite on you... If, in the Gladman simulation, 30 Earth rocks get to Titan in 5 million simulated years, that's 6 Earth rocks per million years. Over the life of the solar system, that's 27,000 microbe bearing Earth rocks for the Titan environment. Makes it sound like a favored holiday destination of Earthly microbes... Interestingly, Freeman Dyson wrote an article in the Atlantic Monthly (Nov, 1997) Warm-Blooded Plants and Freeze-Dried Fish, which used to be viewable on-line and now is not without payment. I quote some of it: Every time a major impact occurs on Europa, a vast quantity of water is splashed from the ocean into the space around Jupiter. Some of the water evaporates, and some condenses into snow. Creatures living in the water far enough from the impact have a chance of being splashed into space and quickly freeze-dried. Therefore, an easy way to look for evidence of life in Europa's ocean is to look for freeze-dried fish in the ring of space debris orbiting Jupiter. And perhaps some of the impact splash escapes Jupiter orbit altogether? Heading which way? I wish Gladman had modeled the reverse case. What are the odds of something splashed up out of Europa arriving on Earth? I'm remembering Ron Baalke's recent post of the article on Weird Rains with its falls of fish, alligators and cows. Any falls of ALIEN fish? Would anyone even recognize an Europan fish as alien? Some of the things that are found in Earth's oceans look pretty alien to me, like benthic fishes. Excuse me, but... you're not from around here, are you? Sterling K. Webb - - Original Message - From: Ron Baalke [EMAIL PROTECTED] To: Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Friday, March 17, 2006 1:03 PM Subject: [meteorite-list] Did Earth Seed Life Elsewhere in the Solar System? http://www.nature.com/news/2006/060313/full/060313-18.html Did Earth seed life elsewhere in the Solar System? Impacts on our planet could have sprayed life into space. Mark Peplow nature.com March 17, 2006 Earthly bacteria could have reached distant planets and moons after being flung into space by massive meteorite impacts, scientists suggest. The proposal neatly reverses the panspermia theory, which suggests that life on Earth was seeded by microbes on comets or meteorites from elsewhere. Both theories envision life spreading through the Solar System in much the same way that germs race around a crowded classroom, says Jeff Moore, a planetary scientist at NASA's Ames Research Center in Moffett Field, California. Once one planet comes down with life, they all get it. Spreading germs Impacts on Mars and the Moon are known to throw rocks into space that end up on Earth as small meteorites. But spraying Earth rocks towards the edges of the Solar System is more difficult, because the material has to move away from the Sun's strong gravity. To find out just how many rocks could reach the outer Solar System, a team of scientists used a computer model to track millions of fragments ejected by a simulated massive impact, such as the one that created the Chicxulub crater some 65 million years ago. Similar sized events are thought to have happened a few times in Earth's history. The researchers looked in part at how many Earthly fragments would reach environments thought to be relatively well suited to life, such as Saturn's moon Titan and Jupiter's moon Europa. I assumed the answer would be very, very few, says Brett Gladman, a planetary scientist at the University of British Columbia, Vancouver, Canada, who led the team. But Gladman was surprised to find that within 5 million years, about 100 objects would hit Europa, while Titan gets roughly 30 hits. He presented the results at the Lunar and Planetary Science Conference in League City, Texas, on 16 March. Tough journey But could bacteria survive the sudden heat and acceleration of being thrown into space? Other researchers at the conference suggest that they can. Wayne Nicholson, a microbiologist from the University of Florida in Gainesville, has tested the idea with a gun the size of a house at NASA's Ames Research Center. He and his colleagues fired a marble-sized pellet at about 5 kilometres per second into a plate that contained bacterial spores in water, in order to simulate a meteorite impact. The debris that scattered upwards was caught in sheets of foam, and the team found that about one in 10,000 bacteria survived. It's an experimental validation of a fairly well established calculation, says Moore. Crash landing Many astrobiologists
[meteorite-list] Did Earth Seed Life Elsewhere in the Solar System?
http://www.nature.com/news/2006/060313/full/060313-18.html Did Earth seed life elsewhere in the Solar System? Impacts on our planet could have sprayed life into space. Mark Peplow nature.com March 17, 2006 Earthly bacteria could have reached distant planets and moons after being flung into space by massive meteorite impacts, scientists suggest. The proposal neatly reverses the panspermia theory, which suggests that life on Earth was seeded by microbes on comets or meteorites from elsewhere. Both theories envision life spreading through the Solar System in much the same way that germs race around a crowded classroom, says Jeff Moore, a planetary scientist at NASA's Ames Research Center in Moffett Field, California. Once one planet comes down with life, they all get it. Spreading germs Impacts on Mars and the Moon are known to throw rocks into space that end up on Earth as small meteorites. But spraying Earth rocks towards the edges of the Solar System is more difficult, because the material has to move away from the Sun's strong gravity. To find out just how many rocks could reach the outer Solar System, a team of scientists used a computer model to track millions of fragments ejected by a simulated massive impact, such as the one that created the Chicxulub crater some 65 million years ago. Similar sized events are thought to have happened a few times in Earth's history. The researchers looked in part at how many Earthly fragments would reach environments thought to be relatively well suited to life, such as Saturn's moon Titan and Jupiter's moon Europa. I assumed the answer would be very, very few, says Brett Gladman, a planetary scientist at the University of British Columbia, Vancouver, Canada, who led the team. But Gladman was surprised to find that within 5 million years, about 100 objects would hit Europa, while Titan gets roughly 30 hits. He presented the results at the Lunar and Planetary Science Conference in League City, Texas, on 16 March. Tough journey But could bacteria survive the sudden heat and acceleration of being thrown into space? Other researchers at the conference suggest that they can. Wayne Nicholson, a microbiologist from the University of Florida in Gainesville, has tested the idea with a gun the size of a house at NASA's Ames Research Center. He and his colleagues fired a marble-sized pellet at about 5 kilometres per second into a plate that contained bacterial spores in water, in order to simulate a meteorite impact. The debris that scattered upwards was caught in sheets of foam, and the team found that about one in 10,000 bacteria survived. It's an experimental validation of a fairly well established calculation, says Moore. Crash landing Many astrobiologists believe that bacteria, once in space, could survive cosmic-radiation exposure during their trip. Unfortunately, a crash landing on Europa would almost certainly sterilize the few rocks that made it that far. But Titan is a different story, says Gladman. The moon's thick atmosphere would first shatter the meteorite before slowing the fragments down; the same process happens with meteorite impacts on Earth. It's a nice safety net, Gladman says. The heat of landing could even melt the ice and open up a short-lived pool of liquid for the visitors, he adds. At the conference, Gladman was asked whether, assuming a few bugs did make it safely on to Titan's surface, they could ever really thrive in the moon's chilly climes of about -170°C. That's for you guys to work out, he told the audience. I'm just the delivery boy. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
