Re: the un-economics of space travel

From: Fred J. McCall (fmccall_at_earthlink.net)
Date: 01/30/05 

Date: Sun, 30 Jan 2005 00:11:00 GMT

henry@spsystems.net (Henry Spencer) wrote:

:In article <1107009290.823533.210790@f14g2000cwb.googlegroups.com>,
:Alex Terrell <alexterrell@yahoo.com> wrote:
:>That can't be the whole story - estimated extraction energies* are:
:>Al203 -> Al 28KWh/kg 0.90
:>Ti02 -> Ti 15KWh/kg 0.69
:>Yet aluminium is much more widely used...
:
:Energy isn't the full story in this case. If the process for extracting
:titanium was as simple and straightforward as the electrolytic process for
:aluminum, titanium would be much more widely used. Titanium extraction is
:complicated and difficult, in addition to being energy-intensive. (It
:doesn't help that titanium's properties are quite sensitive to impurities,
:so the purity requirements are severe.)
:
:There was a recent report of successful development of an electrolytic
:process for titanium. We'll see.
:
:>Titanium is also difficult to work...
:>...And performance wise, it's not that much better than
:>Aluminium/lithium alloys, and for many applications not as good as
:>Carbon Fibre.
:
:It would nevertheless have a fair range of uses, if it were cheap.

But still not as much as one might think. It is inordinately
difficult to work with and tend to eat machine tools. 

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

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