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beamjockey) wrote2007-12-06 01:06 pm
beamjockey) wrote2007-12-06 01:06 pm
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How Low Can You Possibly Sink?
Back in the days of Iron Men and Wooden Reactors, William Mansfield Adams, then a geophysicist at Lawrence Livermore National Laboratory, came up with an idea to explore deep beneath the Earth.
To those interested in constructing probes to penetrate the ice of Europa's surface and investigate the (hypothetical) global ocean beneath, I recommend a study of the Meltmobile. (My word, not Adams's.)
To quote Time's 1964 article on the idea, which is where I heard about it:
Adams' crust piercer, which he patented and assigned to the AEC, is a high-temperature nuclear reactor designed to melt its way into rock. The reactor is 2 ft. to 3 ft. in diameter, and its active material (uranium oxide) is enclosed in a cylinder of beryllium oxide, which serves as a heat insulator. The lower point, mostly tungsten, is heavy, while the upper point, mostly beryllium, is light.
Puddle of Lava. The "Needle Reactor," as Adams calls it, will be placed in a shallow shaft before its nuclear reactor is allowed to go critical. Quickly the temperature will rise to about 1,100° C. (2,012° F.), which is hot enough to melt most rock. Because of the insulation around the midsection, most of the heat will flow downward; soon the lower point will be surrounded by a puddle of lava. The needle reactor will gradually drop into this plastic stuff, and the lava will close over it and solidify.
The reactor will sink toward the center of the earth, moving in a bubble of molten rock. Pressure on its sides will rise enormously, but Adams is not afraid that it will be crushed; it will have no inner cavities to collapse. He figures it can penetrate about 20 miles before pressure and temperature get too high for its comfort. Then it will automatically start to rise.
Blowing Whale. The heavy lower point, Adams explains, will be attached in such a way that the pressure or temperature at a predetermined depth will release it. Freed from this ballast, the needle will be lighter than molten rock, and it will float instead of sinking. At last it will surface like a blowing whale, bringing with it samples of deep-down lava that have forced their way into depressions in its shell.
Here's a pointer to Adams's 1961 Livermore report "A Direct Method for Investigating the Interior of the Earth." I have a paper copy of this filed away, but it doesn't seem to be online.
Adams's paper "A thermal tool for direct investigation of the interior of the earth" is also not online, unless you give Springer a wad of money. But the abstract is available:
Direct access to the crust and the upper portion of the mantle may be achieved by letting a high temperature (>1100°C) reactor core melt the rock in which it is placed and fall through the resulting magma. Data gathering and retrieval seem feasible. A schematic design of the proposed instrument is given. There are many problems concerning the composition and conditions of the interior of the earth which will not be solved upon completion of the projected Mohole Project. Comparison of the continental crust with the oceanic crust, relative distribution of radioactivity under continents and oceans, and the investigation of the mantle itself require access to greater depths than the present drilling techniques permit. To achieve these aims, it is recommended that a dense, heatgenerating object (such as a nuclear reactor core) be placed in the top of a salt dome. The hot object would melt the salt and fall downward through the moten salt. The sinking object would pass out of the source salt bed into rock at such a depth, say 35 000 feet, that if a few percent of H2O is present at that depth, then a granitic rock would melt at about 700°C. However, encounter with SiO2 containing no water would require a much higher temperature of about 1700°C. The type of rock that actually exists immediately below the source salt bed is unknown, but it is probably not a granitic rock. Thermal considerations indicate that the hole will freeze shut after downward passage of the tool, leaving the tool inside a liquid bubble. If the tool can generate heat long enough to melt its way up, as well as down, it may be possible to obtain magma samples. Instrumentation for control and telemetry purposes appears extremely difficult. Initial emphasis is placed on attaining the depth of interest.
Adams's 1962 U.S. patent on the Meltmobile is entitled "NUCLEAR REACTOR APPARATUS FOR EARTH PENETRATION," number 3115194.
Some years ago, I kicked this around in some science newsgroups on Usenet. Unfortunately, I garbled Dr. Adams's middle name at the time. I apologize.
Anybody want to take the plunge?
To those interested in constructing probes to penetrate the ice of Europa's surface and investigate the (hypothetical) global ocean beneath, I recommend a study of the Meltmobile. (My word, not Adams's.)
To quote Time's 1964 article on the idea, which is where I heard about it:
Adams' crust piercer, which he patented and assigned to the AEC, is a high-temperature nuclear reactor designed to melt its way into rock. The reactor is 2 ft. to 3 ft. in diameter, and its active material (uranium oxide) is enclosed in a cylinder of beryllium oxide, which serves as a heat insulator. The lower point, mostly tungsten, is heavy, while the upper point, mostly beryllium, is light.
Puddle of Lava. The "Needle Reactor," as Adams calls it, will be placed in a shallow shaft before its nuclear reactor is allowed to go critical. Quickly the temperature will rise to about 1,100° C. (2,012° F.), which is hot enough to melt most rock. Because of the insulation around the midsection, most of the heat will flow downward; soon the lower point will be surrounded by a puddle of lava. The needle reactor will gradually drop into this plastic stuff, and the lava will close over it and solidify.
The reactor will sink toward the center of the earth, moving in a bubble of molten rock. Pressure on its sides will rise enormously, but Adams is not afraid that it will be crushed; it will have no inner cavities to collapse. He figures it can penetrate about 20 miles before pressure and temperature get too high for its comfort. Then it will automatically start to rise.
Blowing Whale. The heavy lower point, Adams explains, will be attached in such a way that the pressure or temperature at a predetermined depth will release it. Freed from this ballast, the needle will be lighter than molten rock, and it will float instead of sinking. At last it will surface like a blowing whale, bringing with it samples of deep-down lava that have forced their way into depressions in its shell.
Here's a pointer to Adams's 1961 Livermore report "A Direct Method for Investigating the Interior of the Earth." I have a paper copy of this filed away, but it doesn't seem to be online.
Adams's paper "A thermal tool for direct investigation of the interior of the earth" is also not online, unless you give Springer a wad of money. But the abstract is available:
Direct access to the crust and the upper portion of the mantle may be achieved by letting a high temperature (>1100°C) reactor core melt the rock in which it is placed and fall through the resulting magma. Data gathering and retrieval seem feasible. A schematic design of the proposed instrument is given. There are many problems concerning the composition and conditions of the interior of the earth which will not be solved upon completion of the projected Mohole Project. Comparison of the continental crust with the oceanic crust, relative distribution of radioactivity under continents and oceans, and the investigation of the mantle itself require access to greater depths than the present drilling techniques permit. To achieve these aims, it is recommended that a dense, heatgenerating object (such as a nuclear reactor core) be placed in the top of a salt dome. The hot object would melt the salt and fall downward through the moten salt. The sinking object would pass out of the source salt bed into rock at such a depth, say 35 000 feet, that if a few percent of H2O is present at that depth, then a granitic rock would melt at about 700°C. However, encounter with SiO2 containing no water would require a much higher temperature of about 1700°C. The type of rock that actually exists immediately below the source salt bed is unknown, but it is probably not a granitic rock. Thermal considerations indicate that the hole will freeze shut after downward passage of the tool, leaving the tool inside a liquid bubble. If the tool can generate heat long enough to melt its way up, as well as down, it may be possible to obtain magma samples. Instrumentation for control and telemetry purposes appears extremely difficult. Initial emphasis is placed on attaining the depth of interest.
Adams's 1962 U.S. patent on the Meltmobile is entitled "NUCLEAR REACTOR APPARATUS FOR EARTH PENETRATION," number 3115194.
Some years ago, I kicked this around in some science newsgroups on Usenet. Unfortunately, I garbled Dr. Adams's middle name at the time. I apologize.
Anybody want to take the plunge?
no subject
Neat! We can revive Project Pluto to carry the samples back to the lab in a hurry! ;-)
no subject
I could see it getting into some sort of duct and coming up a long way from where it went down, with possible unfortunate results.
no subject
I imagine that this problem could be solved, though. Calculate the maximum radius by which it could go astray, add a safety factor, and choose a vacant lot of the correct size. Such as, say, the Nevada Test Site.
People operating balloons have the same problem, although a 1400 K skin temperature and a load of fission products would certainly complicate things.
On the positive side, most things that go wrong with this system wind up with your waste already buried...
no subject
And winds aloft are rather better charted then the deep rocks. Suppose an unknown fault line turned out to be the path of least resistance?
And consider what happens when that 1400K comes into a body of water.
For example, Lake Powell?
no subject
Also, is there any way to track its progress? Perhaps a high-temperature clockwork noisemaker and a big geophone array?
no subject