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Journey To the Mantle of the Earth By 2020

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  • by gr8_phk (621180) on Thursday March 24, 2011 @09:54AM (#35597850)
    Can we inject all the spent nuclear fuel into the mantle and let it sink to the center? That's what's probably down there anyway...
  • by ElectricTurtle (1171201) on Thursday March 24, 2011 @09:55AM (#35597864)
    As much as people love to get worked up about doomsday science, I think the only real credible threats are grey goo and malevolent strong AI, and both of those things are probably at least another generation or two away.

    There is too much genetic diversity and geographic separation of human populations for a virus to wipe them all out. Even in the middle of some of the worst of plagues some people were immune. The energy involved in achieving any kind of planetary effects is for all intents and purposes currently impossible to produce, and if H bombs didn't ignite the atmosphere, what, if anything, could?
  • Heat issues (Score:5, Interesting)

    by Scootin159 (557129) on Thursday March 24, 2011 @09:57AM (#35597884) Homepage
    The soviets have already tried this [wikipedia.org], but ran into issues with the deep-crust temperatures (570*F when they stopped, but it was still climbing) melting their drill bits. How is this project intending to resolve this issue?
  • by Anonymous Coward on Thursday March 24, 2011 @10:12AM (#35598030)
    So, how about we drill it into the Yellowstone super caldera and allow it to release the pressure so that we don't get that big old explosion that is supposed to happen?
  • by KarrdeSW (996917) on Thursday March 24, 2011 @10:16AM (#35598078)

    You want to put spent nuclear fuel rods into a burning hot ocean of magma in a spot where enormous upward pressure is being exerted? Realistically, a hole in the earth's crust that reaches the mantle already has a name. It's called a volcano. You wouldn't try to shit in an overflowing toilet, would you?

    Though you may have something if you meant that we somehow insert spent fuel into a Subduction Zone [wikipedia.org], where a portion of the crust is sinking into the mantle anyway.

    Personally, I'm all for storing the old fuel until technology becomes sufficiently advanced to use it again, there is still a ton of energy present in it. I'd say the best way to be safe from the stuff it is to bleed it dry.

  • by Dunbal (464142) * on Thursday March 24, 2011 @10:22AM (#35598152)

    The problem is that this mantle is under intense pressure because it has the weight of the Earth's crust bearing down on it. This pressure doesn't matter too much to us because of the weight of the rock being forced down by gravity is exactly balanced by the reaction force of the mantle pushing back up. Except where you get cracks and weaknesses in the rock - and some mantle seeps through, causing a volcano. This pressure is enough to drive the molten rock all the way to the surface.

    Now consider drilling a hole - a hole filled with a tube and presumably some material that is not rock - like air or water (probably water since the distance to the mantle is less from the bottom of the ocean). While water has weight, it doesn't weigh as much as rock - we can prove that because undersea volcanoes exist, too. So basically what you will end up doing is creating your own instant-volcano, the minute you get close enough to the mantle that the remaining rock is weakened, all of that stuff is going to come up - following the path of least resistance.

    I am not saying it's the end of the world - it's not. There are other forces at work too, the mantle will cool on its way up and might only reach the surface slowly, if at all. However you must understand that there will be a tremendous amount of upwards pressure in the shaft. It will be absolutely impossible to "drop something" down there. At best what you would get is a deep hole with your radioactive waste, sitting at the bottom of the sea. At worst you would get the mother of all dirty-bombs, driven by a volcano and spreading this waste all over the ocean floor. It was virtually impossible to drop concrete into the Deepwater Horizon shaft. Imagine the pressures of going much much deeper and what's coming out isn't oil but lava.

  • by ElectricTurtle (1171201) on Thursday March 24, 2011 @10:44AM (#35598424)
    Volcanoes are not primarily caused by local differences in surface strata composition. There is a reason why volcanoes occur along fault lines and especially subduction/divergence zones. Volcanoes are driven in their development and activity primarily by activity in the mantle itself, whether that is melting crust in suduction zones causing plumes of lighter materials or plumes cascading out of the core itself to form hotspots. This is stark contrast to your artificially simplistic description of an equalization of pressure. Volcanoes occur where pressure is not equal.

    The crust itself is surprisingly resilient in places where there are no special pressures. The Kola borehole proved that. Over seven and a half miles down and there was no explosion of pressure. If seven and a half miles of rock can be removed to no ill effect, then substituting it with water should not be as big a problem as you think it is, difference in weight not withstanding.

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