Re: the un-economics of space travel

From: Henry Spencer (henry_at_spsystems.net)
Date: 01/29/05 

Date: Sat, 29 Jan 2005 21:08:34 GMT

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. 

-- 
"Think outside the box -- the box isn't our friend."    |   Henry Spencer
                                -- George Herbert       | henry@spsystems.net

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