Text 33, 47 rader
Skriven 2004-07-18 04:46:12 av Monte Davis (1:379/45)
     Kommentar till text 30 av Geo. (1:379/45)
Ärende: Re: 35 years ago today
==============================
From: Monte Davis <monte.davis@verizon.net>

"Geo." <georger@nls.net> wrote:

>I still have too many doubts, there is the material, temperature range,
>radiation, weather, power transmission, far too many things to solve yet to
>make me believe it's even possible let alone reliable.

Hey, I have more than doubts -- I have absolute *certainty* that nobody could
build one today for a trillion dolars. Unlike most space diatribes, this book
doesn't call for the government or anyone else to Fund The Dream Right Now.

(1) The bulk nanotube material with required strength/weight doesn't exist and
we don't know how to make it. But the carbon nanotubes (CNTs) with more than
enough instrinsic strength do exist. Unlike any previous ultra-strong but
microscopic material, they "want" to be long and perfect -- i.e. if you get the
conditions right, they just keep growing and growing.

(2) There are huge markets for bulk materials made from CNTs, regardless of
space elevators. The research is widespread and well-funded; I've been watching
chemical process science and engineering for 35 years, and have never seen a
sub-field this hot. So... imagine a technology requiring incredibly precise
control and alignment of a material fabricated on a micron scale; it could
easily cost half a billion for a fab plant. Does that sound familiar? <g>

(3) Yes, space conditions are tough. There will definitely be time lag between
CNT bulk material #1, strong and light enough to build a Gibraltar Bridge or
whatever, and the Goldilocks version that is strong and light enough *and*
resistant to space conditions. But it's not black magic -- we've successfully
tweaked or coated many materials for space over the years.

(4) Power transmission's comparatively easy. There's no new physics or
bleeding-edge technology in scaling up lasers, directing them with adaptive
mirrors, making photovoltaic cells to convert their beams, or designing
reliable electric motor drives: just a lot of good design needed.

>I mean heck we can't even string high tension power lines so they don't sag
>into the tree yet <g>.

In a space elevator the cable hangs exactly the way gravity most wants it to
hang. It's not nice to try to fool Mother Nature; it's nice to work with her.
<g>

-Monte

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