[meteorite-list] OT: Asteroidal and Lunar Materials
From: Gerald Flaherty <grf2_at_meteoritecentral.com>
Date: Sun May 22 11:27:13 2005 Message-ID: <001501c55ee2$b651ef50$2f01a8c0_at_Dell> I absolutely love it!!"Save Our Astroids" Talk about a "steel trap mind". Whoops that might no longer be a positive compliment!! Another wonderful weave with reality based imagination! Thanks Sterling. I may not have the math background but I sure am able to follow your engineered imaginative joutney into the future. Jerry ----- Original Message ----- From: "Sterling K. Webb" <kelly_at_bhil.com> To: "Meteorite List" <meteorite-list_at_meteoritecentral.com> Sent: Saturday, May 21, 2005 9:35 PM Subject: [meteorite-list] OT: Asteroidal and Lunar Materials > Hi, > > A while back there was a mini-thread about the cost of returning > lunar materials to Earth and the effect of economies of scale on that > cost. These cost concerns are similar to a much more analyzed topic: > returning asteroidal materials to Earth. See John Lewis' book "Mining > The Sky." > Even so, to date these discussions have been about materials that > could be obtained on Earth (except for Helium-3). The chief point to > remember about economies is that they change when the material commodity > is both required and can not be obtained elsewhere. > > Here's an example: Imagine you want to build a bridge out of iron > across a 100 foot chasm. The simplest way is to take a 100 foot long > slab of iron (or steel), twenty feet wide and 10 feet thick, and flop it > down. Inelegant, but a solution. > More elegant is to take a very thin slab of iron and attach a > variety of iron trusses underneath it, designed to support the stresses > of the bridge. You use much less iron and get a bridge just as strong > or stronger. A more elegant solution. > Even more elegant is build the above example of a bridge very > lightly indeed and support it with iron cables from towers. Now we're > up to Golden Gate elegant, less material, more strength, all gotten by > subdividing the structural shape into smaller and smaller internally > braced "voids." > In older aircraft and race car design, we can see engineers drilling > rows of big holes in beams and such like to create a more favorable > strength/weight ratio. You engineers out there know all about this, of > course. > The next logical step would be to carry the principle down to the > micro scale, where what appear to be solid structural members are > themselves smaller and smaller internally braced voids. But both micro- > and nano- fabrication is too fantastically expensive to contemplate. > > Hey, where do the asteroids (and the Moon) come into this?! > > Here it is. You've got all this iron (or natural stainless steel) > in free orbit, zero gee, or at least, micro-gee. Melt it in a > cylindrical electric induction furnace and eject it through a special > nozzle at one end. (The furnace is electric because the sunshine is > free and in constant supply.) > The exit nozzle's walls have a multitude of injectors that inject a > whoppingly large number of bubbles of nitrogen gas into the molten steel > as it emerges. The injector banks are computer controlled for rate, > pressure, pulsation pattern, and so forth. > As the molten asteroidal steel foam exits the furnace into vacuum, > it expands from the internal expansion of the nitrogen bubbles that have > been injected into it. The desired goal is to regulate the process so > that the final product contains a very large number of small voids which > butt up to each other forming regular and irregular polyhedra with thin > steel walls separating them. > The result is a material with a density about 1/3rd that of water, > twenty times lighter than a piece of steel the same size and shape, a > structural strength greater than the best aircraft grade aluminum, and a > strength / weight ratio that is an engineer's dream! > Because it's fabricated in zero-gee, it can be produced in virtually > any shape without distortion and made in gigantic sizes limited only by > the capacity of the furnace producing it. ("You want an I-beam how many > miles long?") > > If any of you out there are engineers, your mouths should be already > watering. If not, you're no engineer, at least not one in the mold of > Isabard Kingdom Brunel. > Do you want to build a bridge across the 29-mile Straight of > Gibraltar? No problem. Do you want to build a skyscraper five miles > high? No problem. Do you want to build a Tokyo-sized city that will > float on the sea? No problem. Do you want to build a...? You get the > idea. > From fabrication in zero-gee, the huge pieces of Foam Steel will be > spun sprayed with an ablative polymer and gently de-orbited into the > central Pacific Ocean, after which they will be recovered, transported > to the work site, cleaned of polymer, and put in use. > Why the Pacific? Well, you know, there are always these silly folks > who get unreasonably nervous about mile long pieces of steel falling out > of the sky too near them; it's just good public relations to use the > middle of the Pacific. Remember, Foam Steel will float! In fact, the > density of Foam Steel could be only about twice that of Balsa wood! > Foam Steel will float only 1/3rd submerged. No problem. Hello, Hawaii! > > The First Iron Age is over. The Second Iron Age is about to begin. > Here is the miracle material of which the future will be built, and it > must come from space because that is the only place where it can be > made, so the raw material is most economically obtained from asteroids > (or the Moon). > It would make no economic sense to boost Earth steel into orbit to > be re-fabricated as Foam Steel! It is conceivable that the demand for > Foam Steel could become so great that one might foresee the growth of an > environmental slash wilderness movement to "Save Our Asteroids!" > So, study those iron asteroids while you've still got them. > > > > Sterling K. Webb > > > ______________________________________________ > Meteorite-list mailing list > Meteorite-list_at_meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list Received on Sun 22 May 2005 11:27:05 AM PDT |
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