"Gary Heston" <gheston@hiwaay.net> wrote in message
news:10bk5ku343l844c@corp.supernews.com...

In article <REM-2004may29-008@Yahoo.Com>,  <RobertMaas@YahooGroups.Com>

wrote:

From: Joe Strout <joe@strout.net>
After we've used the materials in the asteroid belt, and dismantled
the moons of the giant planets, the obvious next targets are the Kuiper
belt and the Oort cloud.  Our Oort cloud extends about three light
years out from the Sun.  If Alpha Centauri has a similar Oort cloud,
then its cloud overlaps with ours.  So by colonizing the Oort cloud,
you're already starting to colonize the next star.

Where do farcomet homesteaders get a supply of energy?  [ ... ]

Breeder reactors should work fine.

I assume you mean fission breeders.  So where do the homesteaders
get their supply of fisionables?  Trading with the inner system
or local resources?  We are talking about thousands to tens of
thousands of years from now.  Fissionables, including U238, are
an exhaustible and nonrenewable resource.  Will there be any left?

On the other hand, there is fusion.  I am willing to believe that
technology will exist for D-T fusion with lithium blankets by
then, though there will be a certain minimum installation size.
I am also willing to believe in D-He3 and H-B fusion.  I am not
willing to believe in D + D -> He4 or 4H -> He4 + 2e in this time
frame, if ever.

It seems to me that while the supply of H and D is nearly
inexhaustible, supplies of Li and B are likely to be just as
exhaustible as are supplies of fissionables.  So, I'm curious
whether there is any such thing as a fusion breeder reactor
in which excess D is converted (perhaps endothermically) into
something more useful?

Of course, even He3 is practically inexhaustible if you can
extract it from gas giant atmospheres.  But getting it out
then to the Oort cloud thru trade seems very problematic.