       TRAVELLER Digest 15

Topics covered in this issue include:

  1) Re: HIWG by Kerry Harrison <kerry@io.com>
  2) Beanstalks and ContraGrav by jeff.zeitlin@execnet.com (Jeff Zeitlin)

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Date: Sat, 20 Aug 1994 14:30:59 -0500 (CDT)
From: Kerry Harrison <kerry@io.com>
To: traveller@MPGN.COM
Subject: Re: HIWG
Message-ID: <Pine.3.89.9408201452.B19058-0100000@pentagon.io.com>


On Sat, 20 Aug 1994 traveller@MPGN.COM wrote:

> Date: Fri, 19 Aug 1994 14:54:06 -0500 (CDT)
> From: ccjoe@showme.missouri.edu (Joseph Heck)
> Subject: Re: HIWG file
> 
> Umm.. I received those files courtesy of Stewart (in the UK), and they are
> in _no_ way the "one and only" HIWG archives. HIWG does have a listserv
> running off SJG's setup (io.com), but I have very little information on it.
> 
> Feel free to check out the files, but I don't swear a thing about them - I've
> simply made them available.
> 
> oh - ghost.cc.missouri.edu is both a FTP and Gopher server.
> -- 

Joe,

The HIWG Mailing List running off of io.com is a mainly just a private 
discussion area for HIWG members, it was created in an effort to make 
communications between our members a bit easier.

Kerry Harrison,
HIWG-List Admin

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Date: Fri, 19 Aug 94 20:08:00 -0500
From: jeff.zeitlin@execnet.com (Jeff Zeitlin)
To: TRAVELLER@MPGN.COM
Subject: Beanstalks and ContraGrav
Message-ID: <1.191474.256.0CB5E5C8@execnet.com>

Subject: Beanstalks and ContraGrav

Alvin Plummer on Beanstalks and ContraGrav...

T::>Previously, I asked a question on the Beanstalk, and someone said that the
 ::>beanstalk is impossible, since it's weight needed would escalate faster
 ::>than it's height. (Right?)

T::>Well, what about contragrav attatched to the beanstalk?  If this can be
 ::>done, I _think_ that the beanstalk could be built at TL 11, say.

 There's another thing to consider: A rigid structure along the 
 lines of a Beanstalk would get torn down by 
 planetary-rotation-induced stresses.  Remember, the surface of the 
 Earth is moving at a speed of 1,600 km/h (approximately) if at sea 
 level, and the higher you go, the faster the speed needed to 
 maintain geosynchronicity.  But, the higher you go, the slower the 
 "natural" orbital speed of an object.  Also, no known material is 
 rigid enough to use in continuous structures that go over some 
 unknown (to me) maximum height.  So materials technology puts a 
 limit on a single-structure Beanstalk.  

 On the other hand, once you can generate "infinite length" cables 
 (the favorite buzzword here is "single-crystal extrusion"), 
 there's no reason that you can't put Beanstalk High over, say, 
 Quito, Ecuador, and run a couple of loops of "magic cable" between 
 BSH and Q as your surface-to-orbit transport.

 Of course, the issue of cost comes into play.  Certainly, the 
 cable beanstalk will be cheaper than a single-structure beanstalk 
 - but will it be cheaper than building and operating (mostly the 
 latter) the reuseable orbital craft that will almost certainly be 
 easily available (consider the US Space Shuttle - we have several 
 of them; if Space Station Freedom were to become a tourist 
 attraction, those shuttles are ready-made "busses" to transport 
 between SSF and Canaveral/Edwards).

 Of course, once you have an economical CG, the whole issue is 
 moot; the way to go is with CG versions of the Space Shuttle - 
 cheaper to build, and almost certainly cheaper to operate.  So I 
 would tend to say that the window of opportunity for a beanstalk 
 is very narrow, and may possibly be narrower than the amount of 
 time that would be needed to actually construct the damn thing.
==========================================================================
Jeff Zeitlin                                      jeff.zeitlin@execnet.com
---
 ~ QMPro 1.52 ~ Multitasking: Screwing up several things at once

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End of TRAVELLER Digest 15
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