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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: Re: Another Use for Tethers
Message-ID: <8601161312.AA15050@s1-b.arpa>
Date: Thu, 16-Jan-86 07:51:54 EST
Article-I.D.: s1-b.8601161312.AA15050
Posted: Thu Jan 16 07:51:54 1986
Date-Received: Sat, 18-Jan-86 00:44:06 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 19

>Umm, what stops the cables from just wrapping around the station?  This
>scheme would work, but you would need rigid 'towers' instead of cables, and
>the mass needed for these towers might be large enough to offset any fuel
>savings.  One last point, the cables will only be stationary with respect
>to the station, and they will still have a considerable amount of angular
>momentum. Retracting them would spin up the station even more, just like
>a spinning figure skater.  

By stationary I meant with respect to an inertial reference frame, not
the space station (you torque the cables until they stop).  The point
about winding the cables up is a good one, but can be overcome by not
torquing them even that much, so leaving them with some residual
rotation.  This rotation can be eliminated by firing the rockets at the
ends again, but in the opposite direction.

One might acquire angular momentum by catching masses at the ends of
the cables.  This would transfer angular momentum from the orbits of
the masses to the rotation of the structure; because the orbits have
such large radii this could be extremely mass efficient.