231 lines
14 KiB
Plaintext
231 lines
14 KiB
Plaintext
ÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜ ÜÜÜÜ
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ÜÛÛÛÛÛÛÛÛßÛßßßßßÛÛÜ ÜÜßßßßÜÜÜÜ ÜÛÜ ÜÛÛÛÛÛÛÛÛÜÜÜÜÜÛßß ßÛÛ
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ßÛÛÛÛÛÛÛÛÛÛÛÛÛÛÜ ßÛÛ ÜÛÛÛÜÛÛÜÜÜ ßÛÛÛÛÜ ßÛÛÛÛÛÛÛÜÛÛÜÜÜÛÛÝ Ûß
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ßßßÛÛÛÛÛÛÛÛÛÛÜ ÞÝ ÛÛÛÛÛÛÛÛÛÛÛßßÛÜÞÛÛÛ ÛÛÛÛÛÜ ßßÛÛÛÞß
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Mo.iMP ÜÛÛÜ ßÛÛÛÛÛÛÛÝÛ ÞÛÛÛÛÛÛÛÛÛ ÞÛÛÛÛ ÞÛÛÛÛÛÝ ßÛß
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ÜÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛÝ ÛÛÛ ÛÛÛÛÛÛ
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ÜÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛ ÞÛÛÛÛÛÛÛÛ ß ÞÛÛÛÛÛÛÜ ÜÛ
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ÜÛÛÛÛÛÛÛÝ ÛÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÞÛÛÛÛÛÛÛÛÛß
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ÜÛßÛÛÛÛÛÛ ÜÜ ÛÛÛÛÛÛÛÛÝ ÛÛÞÛÛÛÛÛÝ ÞÛÛÛÛÛÛßß
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ÜÛßÛÛÛÛÛÛÜÛÛÛÛÜÞÛÛÛÛÛÛÛÛ ÞÛ ßÛÛÛÛÛ Ü ÛÝÛÛÛÛÛ Ü
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ÜÛ ÞÛÛÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛ ßÛÜ ßÛÛÛÜÜ ÜÜÛÛÛß ÞÛ ÞÛÛÛÝ ÜÜÛÛ
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ÛÛ ÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛÛÜ ßÛÜ ßßÛÛÛÛÛÛÛÛÛß ÜÜÜß ÛÛÛÛÜÜÜÜÜÜÜÛÛÛÛÛß
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ßÛÜ ÜÛÛÛß ßÛÛÛÛÛÛÛÛÛÛÜ ßßÜÜ ßßÜÛÛßß ßÛÛÜ ßßßÛßÛÛÛÛÛÛÛßß
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ßßßßß ßßÛÛß ßßßßß ßßßßßßßßßßßßß
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ARRoGANT CoURiERS WiTH ESSaYS
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Grade Level: Type of Work Subject/Topic is on:
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[ ]6-8 [ ]Class Notes [Essay on Mining in Space]
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[ ]9-10 [ ]Cliff Notes [ ]
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[x]11-12 [x]Essay/Report [ ]
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[ ]College [ ]Misc [ ]
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Dizzed: o4/95 # of Words:2084 School: ? State: ?
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
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Mining
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in
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Space
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--
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AIAA and New York Academy of Sciences
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On December 10, 1986 the Greater New York Section of the American
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Institute of Aeronautics and Astronautics (AIAA) and the engineering
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section of the New York Academy of Sciences jointly presented a program on
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mining the planets. Speakers were Greg Maryniak of the Space Studies
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Institute (SSI) and Dr. Carl Peterson of the Mining and Excavation
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Research Institute of M.I.T.
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Maryniak spoke first and began by commenting that the quintessential
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predicament of space flight is that everything launched from Earth must be
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accelerated to orbital velocity. Related to this is that the traditional
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way to create things in space has been to manufacture them on Earth and
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then launch them into orbit aboard large rockets. The difficulty with this
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approach is the huge cost-per-pound of boosting anything out of this
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planet's gravity well. Furthermore, Maryniak noted, since (at least in the
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near to medium term) the space program must depend upon the government for
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most of its funding, for this economic drawback necessarily translates
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into a political problem.
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Maryniak continued by noting that the early settlers in North America
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did not attempt to transport across the Atlantic everything then needed to
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sustain them in the New World. Rather they brought their tools with them
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and constructed their habitats from local materials. Hence, he suggested
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that the solution to the dilemma to which he referred required not so much
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a shift in technology as a shift in thinking. Space, he argued, should be
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considered not as a vacuum, totally devoid of everything. Rather, it should
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be regarded as an ocean, that is, a hostile environment but one having
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resources. Among the resources of space, he suggested, are readily
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available solar power and potential surface mines on the Moon and later
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other celestial bodies as well.
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The Moon, Maryniak stated, contains many useful materials. Moreover, it
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is twenty-two times easier to accelerate a payload to lunar escape velocity
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than it is to accelerate the identical mass out of the EarthUs gravity
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well. As a practical matter the advantage in terms of the energy required
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is even greater because of the absence of a lunar atmosphere. Among other
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things this permits the use of devices such as electromagnetic
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accelerators (mass drivers) to launch payloads from the MoonUs surface.
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Even raw Lunar soil is useful as shielding for space stations and other
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space habitats. At present, he noted, exposure to radiation will prevent
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anyone for spending a total of more than six months out of his or her
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entire lifetime on the space station. At the other end of the scale, Lunar
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soil can be processed into its constituent materials. In between steps are
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also of great interest. For example, the MoonUs soil is rich in oxygen,
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which makes up most of the mass of water and rocket propellant. This oxygen
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could be RcookedS out of the Lunar soil. Since most of the mass of the
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equipment which would be necessary to accomplish this would consist of
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relatively low technology hardware, Maryniak suggested the possibility that
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at least in the longer term the extraction plant itself could be
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manufactured largely on the Moon. Another possibility currently being
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examined is the manufacture of glass from Lunar soil and using it as
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construction material. The techniques involved, according to Maryniak, are
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crude but effective. (In answer to a question posed by a member of the
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audience after the formal presentation, Maryniak stated that he believed
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the brittle properties of glass could be overcome by using glass-glass
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composites. He also suggested yet another possibility, that of using Lunar
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soil as a basis of concrete.)
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One possible application of such Moon-made glass would be in glass-glass
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composite beams. Among other things, these could be employed as structural
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elements in a solar power satellite (SPS). While interest in the SPS has
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waned in this country, at least temporarily, it is a major focus of
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attention in the U.S.S. R. , Western Europe and Japan. In particular, the
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Soviets have stated that they will build an SPS by the year 2000 (although
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they plan on using Earth launched materials. Similarly the Japanese are
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conducting SPS related sounding rocket tests. SSI studies have suggested
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that more than 90%, and perhaps as much as 99% of the mass of an SPS can
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be constructed out of Lunar materials.
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According to Maryniak, a fair amount of work has already been performed
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on the layout of Lunar mines and how to separate materials on the Moon.
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Different techniques from those employed on Earth must be used because of
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the absence of water on the Moon. On the other hand, Lunar materials
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processing can involve the use of self-replicating factories. Such a
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procedure may be able to produce a so-called Rmass payback ratioS of 500 to
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1. That is, the mass of the manufactories which can be established by this
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method will equal 500 times the mass of the original RseedS plant emplaced
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on the Moon.
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Maryniak also discussed the mining of asteroids using mass-driver
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engines, a technique which SSI has long advocated. Essentially this would
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entail a spacecraft capturing either a sizable fragment of a large asteroid
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or preferably an entire small asteroid. The spacecraft would be equipped
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with machinery to extract minerals and other useful materials from the
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asteroidal mass. The slag or other waste products generated in this process
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would be reduced to finely pulverized form and accelerated by a mass driver
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in order to propel the captured asteroid into an orbit around Earth. If the
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Earth has so-called Trojan asteroids, as does Jupiter, the energy required
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to bring materials from them to low Earth orbit (LEO) would be only 1% as
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great as that required to launch the same amount of mass from Earth. (Once
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again, moreover, the fact that more economical means of propulsion can be
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used for orbital transfers than for accelerating material to orbital
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velocity would likely make the practical advantages even greater. )
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However, Maryniak noted that observations already performed have ruled out
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any Earth-Trojan bodies larger than one mile in diameter.
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In addition to the previously mentioned SPS, another possible use for
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materials mined from planets would be in the construction of space
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colonies. In this connection Maryniak noted that a so-called biosphere was
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presently being constructed outside of Tucson, Arizona. When it is
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completed eight people will inhabit it for two years entirely sealed off
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from the outside world. One of the objectives of this experiment will be to
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prove the concept of long-duration closed cycle life support systems.
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As the foregoing illustrates, MaryniakUs primary focus was upon mining
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the planets as a source for materials to use in space. Dr. PetersonUs
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principal interest, on the other hand, was the potential application of
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techniques and equipment developed for use on the Moon and the asteroids to
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the mining industry here on Earth. Dr Peterson began his presentation by
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noting that the U. S. mining industry was in very poor condition. In
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particular, it has been criticized for using what has been described as
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Rneanderthal technology. S Dr. Peterson clearly implied that such
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criticism is justified, noting that the sooner or later the philosophy of
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not doing what you canUt make money on today will come back to haunt
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people. A possible solution to this problem, Dr. Peterson, suggested, is a
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marriage between mining and aerospace.
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(As an aside, Dr. PetersonUs admonition would appear to be as applicable
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to the space program as it is to the mining industry, and especially to
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the reluctance of both the government and the private sector to fund
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long-lead time space projects. The current problems NASA is having getting
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funding for the space station approved by Congress and the failure begin
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now to implement the recommendations of the National Commission on Space
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particularly come to mind.)
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Part of the mining industryUs difficulty, according to Dr. Peterson is
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that is represents a rather small market. This tends to discourage long
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range research. The result is to produce on the one hand brilliant
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solutions to individual, immediate problems, but on the other hand overall
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systems of incredible complexity. This complexity, which according to Dr.
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Peterson has now reached intolerable levels, results from the fact that
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mining machinery evolves one step at a time and thus is subject to the
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restriction that each new subsystem has to be compatible with all of the
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other parts of the system that have not changed. Using slides to illustrate
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his point, Dr. Peterson noted that so-called RcontinuousS coal mining
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machines can in fact operate only 50% of the time. The machine must stop
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when the shuttle car, which removes the coal, is full. The shuttle cars,
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moreover, have to stay out of each others way. Furthermore, not only are
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Earthbound mining machines too heavy to take into space, they are rapidly
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becoming too heavy to take into mines on Earth.
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When humanity begins to colonize the Moon, Dr. Peterson asserted, it
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will eventually prove necessary to go below the surface for the
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construction of habitats, even if the extraction of Lunar materials can be
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restricted to surface mining operations. As a result, the same problems
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currently plaguing Earthbound mining will be encountered. This is where
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Earth and Moon mining can converge. Since Moon mining will start from
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square one, Dr. Peterson implied, systems can be designed as a whole rather
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than piecemeal. By the same token, for the reasons mentioned there is a
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need in the case of Earthbound mining machinery to back up and look at
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systems as a whole. What is required, therefore, is a research program
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aimed at developing technology that will be useful on the Moon but
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pending development of Lunar mining operations can also be used down here
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on Earth.
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In particular, the mining industry on Earth is inhibited by overly
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complex equipment unsuited to todayUs opportunities in remote control and
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automation. It needs machines simple enough to take advantage of
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tele-operation and automation. The same needs exist with respect to the
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Moon. Therefore the mining institute hopes to raise enough funds for
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sustained research in mining techniques useful both on Earth and on other
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celestial bodies as well. In this last connection, Dr. Peterson noted that
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the mining industry is subject to the same problem as the aerospace
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industry: Congress is reluctant to fund long range research. In addition,
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the mining industry has a problem of its own in that because individual
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companies are highly competitive research results are generally not shared.
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Dr. Peterson acknowledged, however, that there are differences
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between mining on Earth and mining on other planetary bodies. The most
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important is the one already mentioned-heavy equipment cannot be used in
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space. This will mean additional problems for space miners. Unlike space
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vacuum, rock does not provide a predictable environment. Furthermore, the
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constraint in mining is not energy requirements, but force requirements.
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Rock requires heavy forces to move. In other words, one reason earthbound
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mining equipment is heavy is that it breaks. This brute force method,
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however, cannot be used in space. Entirely aside from weight limitations,
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heavy forces cannot be generated on the Moon and especially on asteroids,
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because lower gravity means less traction. NASA has done some research on
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certain details of this problem, but there is a need for fundamental
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thinking about how to avoid using big forces.
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One solution, although it would be limited to surface mining, is the
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slusher-scoop. This device scoops up material in a bucket dragged across
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the surface by cables and a winch. One obvious advantage of this method is
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that it by passes low gravity traction problems. Slushers are already in
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use here on Earth. According to Peterson, the device was invented by a
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person named Pat Farell. Farell was, Peterson stated, a very innovative
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mining engineer partly because be did not attend college and therefore did
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not learn what couldnUt be done.
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Some possible alternatives to the use of big forces were discussed
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during the question period that followed the formal presentations. One was
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the so called laser cutter. This, Peterson indicated, is a potential
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solution if power problems can be overcome. It does a good job and leaves
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behind a vitrified tube in the rock. Another possibility is fusion
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pellets, which create shock waves by impact. On the other hand, nuclear
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charges are not practical. Aside from considerations generated by treaties
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banning the presence of nuclear weapons in space, they would throw material
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too far in a low gravity environment.
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