[meteorite-list] OT: Asteroidal and Lunar Materials

[Gerald Flaherty]

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
>
>
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