"Paul F. Dietz" wrote:

:Fred J. McCall wrote:
: Alain Fournier wrote:
:
: :Fred J. McCall wrote:
: : "Paul F. Dietz" wrote:
: :
: : :Nonsense. Many many things have become affordable because
: : f advances not specifically directed at those things.
: :
: : If you think it's nonsense, please tell us just what technologies you
: : think are sufficiently 'dual use' to Mars flights and something else
: : (and what that something else is) so as to drive down the costs of
: : Mars flights.
: :
: :
: :New stronger materials (a dual use, airplanes and others), electronics
: dual use home computers and others),
:
: This doesn't NECESSARILY drive down costs. I seem to recall that a
: decade and more ago some folks arrived at the conclusion that using
: swaged steel for the body of an expendable launcher was more
: economical than using more exotic materials that would be stronger and
: lighter.
:
:Sure. But even that gets cheaper with time -- high strength steel
:is increasingly used in mundane applications like tell buildings
:and automobiles, so even it will get cheaper with time. For that
:matter, steel production itself will become more efficient with
:time, as mills are increasingly optimized and automated.

But not much. Looking at 40 years worth of steel prices (1959-1998),
one does see a declining trend in price (hot rolled steel bar in
constant 1992 dollars) from around $27/100 lb down to $16/100 lb.
While there are a bunch of jumps UPWARD during the 1970's the general
trend line looks fairly constant, judging by eye. So the price is
dropping about two bits per year per 100 lbs of steel.

This is hardly a change that is going to drive down the price of
anything in a hurry and at some point it has to taper off, as I doubt
that steel is ever going to become free.

:I repeat: your position would require that the technologies for
:Mars vehicles be completely disjoint from those used in the rest
f the technosphere.

You can repeat it all you like, but you haven't shown it to be true.
That takes real data and real examples.

The data so far seem to indicate that things aren't getting cheaper
very fast at all. Certainly not fast enough to make much difference
during our lifetimes.

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney