Re: Space Exploitation

From: Kieran A. Carroll (kac_at_dynacon.ca)
Date: 06/11/04 

Date: 11 Jun 2004 13:19:32 -0700

"Terry Goodrich" <terry@csmgdesign.com> wrote in message news:<Vdavc.1959$2M1.738@bignews3.bellsouth.net>...
> > At current prices, it would probably have to be something that can
> > *only* be made in space (and that people will pay a lot of money for,
> > like a cure for cancer).
>
> I agree, but what has there been that could only be made in space?

One type of material, that is expected to have interestingly useful
properties, that may only be able to be manufactured into product form
in microgravity, is ZBLAN glass (e.g., see
http://science.nasa.gov/newhome/headlines/msad05feb98_1.htm). When
used to make optical fibers, this is anticipated to result in fibers
with very low loss per unit length. (Most optical fibers absorb half
of the light put into them, in distances on the order of a km (>1
dB/km attenuation). ZBLAN glass has an anticipated attenuation of as
low as 0.002 dB/km (per http://optics.nasa.gov/current.html))

What's this good for? In the optical fiber based communicatiosn
industry, this could allow for a much smaller number of repeaters (a
very significant factor for undersea cables). (Of course, the market
for optical fiber for comms is pretty soft just now, after the bubble
burst a couple of years ago; however, demand will likely eventually
pick up again.) Myself, I was looking at this for the purpose of
transmitting power via laser light over optical fiber, in which case
reducing attenuation is probably necessary to making this viable for
most applications.

Looks like ZBLAN formed under gravitational stress doesn't have the
nice low-loss property. "Processing ZBLAN in microgravity suppresses
crystallization and improves the transmission." Sounding rocket and
KC-135 experiments have been done by researchers from MSFC, with
promising results. Shuttle flights were planned; I'm not sure if
they've happened yet. I can't find any news about this since 2000; has
anyone else heard what's happening with this?

If the production technology works out, and a merket for this can be
developed, this could motivate an orbital factory for pulling ZBLAB
fibers from boules sent up from Earth (or heat-treating spools of
ZBLAN fiber that are sent up from Earth, to remove crystalline
defects.)

- Kieran A. Carroll
  Dynacon