[meteorite-list] OT: Asteroidal and Lunar Materials

[Gerald Flaherty]

Gotcha Marc!
----- Original Message ----- 
From: "Marc Fries" <m.fries at gl.ciw.edu>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Sunday, May 22, 2005 1:08 PM
Subject: Re: [meteorite-list] OT: Asteroidal and Lunar Materials


> Howdy
>
>   Interesting, but it needs work.  First off, where do you get the
> nitrogen?  Asteroids are devoid of the stuff, which means hauling large
> amounts of liquid nitrogen from the Earth's gravity well ($$$$!).
>   Second, you've got big metallurgy problems.  Fe-Ni is not "stainless
> steel", as anyone who has watched their iron meteorite rust can attest
> to.  Stainless steel is an iron-chromium alloy.  Also, asteroidal metal
> contains large amounts of sulfides, which acts to embrittle metals.  As
> a cautionary tale in that regard, it was discovered (far too late) that
> the iron used to build the Titanic was very sulfide-rich and the
> resulting embrittlement was a likely cause of its' sinking:
>
> http://dwb.unl.edu/Teacher/NSF/C10/C10Links/chemistry.about.com/library/weekly/aa022800a.htm
>
>  In addition to sulfides, there will be silicates and minor refractory
> components which will basically rip the bubbles as they form:
>
> http://epubl.ltu.se/1402-1617/2002/344/index-en.html
>
>  As a macro-scale example look at Coke cans, which have to be made from
> an aluminum alloy that is even more pure than aircraft aluminum to keep
> from ripping open under extreme plastic deformation when the can is
> made.  Finally, dropping a kms-long rod of material, no matter how
> light, through the Earth's atmosphere at many km/s will break or deform
> the surviving pieces considerably.  Perhaps this would be better off as
> a building material that is not intended to land on a planetary body
> (space stations?).
>
>   I hate to keep playing the spoil-sport in these emails, but I hope
> y'all will look at this as a critical evaluation of the problems
> involved and not just a "told-you-so-a-thon".  If we understand the
> problems then someone can work to overcome them.
>
> Cheers,
> MDF
>
>
>>> 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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>
>
> -- 
> Marc Fries
> Postdoctoral Research Associate
> Carnegie Institution of Washington
> Geophysical Laboratory
> 5251 Broad Branch Rd. NW
> Washington, DC 20015
> PH:  202 478 7970
> FAX: 202 478 8901
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