space manufactuof acrylic vs. glass?

Acrylic would require an extensive in space
infrastructure to manufacture as well as shipment to
orbit of large quantities of specialized materials.
Glass could be made in situ from available materials,
ie, the SiO2 in asteroids/lunar regolith and from
available solar radiation, ie, at 1400 watts/m2
there's pleanty of heat available for melting the rock
with a 100 m2 collecting surface. Check out
MythBusters use of flat mirrors to ignite a wooden
boat 100 feet away.

GAry 7

>
> > Seems like most all of the peer-reviewed space
> > habitat designs have assumed use of glass. I
> strongly suspect this is
> > because when we're talking about needing something
> by the square mile, we'd darn
> > well better be talking about the cheapest
> substance with the simplest materials
> > processing which can do the job.
>
> That sounds sensible, but I'm having trouble backing
> it up with figures. A square foot of 0.5" acrylic
> sheet is $10.50, which works out to about $8900/m^3
> [1]. A 15 mm rod of clear fused quartz glass is
> $26.70/foot, which works out to over $495000 (yes,
> half a million!) per m^3. A case of Pyrex glass
> rods is $111, and works out to $22000/m^3 -- a lot
> cheaper than fused quartz, but still about 2.5 times
> more expensive than acrylic.
>
> Of course, I'm sure there are cheaper sources for
> bulk glass, but then that's probably true of acrylic
> too; I just quoted the first source I could find of
> sheet/bar/rod stock.
>
> On the other hand, I have a vague idea how glass is
> made; I have no idea how acrylic is made and whether
> it would be a good fit for space processing or
> resources. But if the production process were a lot
> more expensive (on Earth) than that for glass, you
> wouldn't expect to be finding it so cheap.
>
> I wonder if perhaps acrylic wasn't well known in the
> 1970s, so glass was assumed, and now it's just a
> matter of habit?
>
> Best,
> - Joe
>
> [1] http://www.scicominc.com/plastic_sheet_stock.htm
> [2]
>
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