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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.space
Subject: Re: Space stations.
Message-ID: <3504@utzoo.UUCP>
Date: Wed, 1-Feb-84 17:49:58 EST
Article-I.D.: utzoo.3504
Posted: Wed Feb  1 17:49:58 1984
Date-Received: Wed, 1-Feb-84 17:49:58 EST
References: <578@pyuxqq.UUCP>, <1177@aluxp.UUCP>
Organization: U of Toronto Zoology
Lines: 24

The reason why nobody is looking at ring-shaped space stations is
that the current space-station plans do not use centrifugal force
to supply artificial gravity.  Currently-planned stations will have
a free-fall environment throughout.  Interest in artificial gravity
declined steeply in the 60's, when experimental evidence confirmed
that human beings were not seriously affected by moderate periods
of time in free-fall conditions.  It may well be necessary in the
more distant future, when really long stays start to become a serious
possibility, but current plans aren't that fancy.

There is also a secondary issue here:  current thought is that if
people are going to be coming and going between a rotating section
and a free-fall section, the rotation rate should be quite low.
This is not a mechanical question but a matter of worries about
things like inner-ear upsets.  Last I heard, the best guess was that
if you want arbitrarily-chosen people to come and go between the two
environments over long periods, anything above 1 RPM is dubious.
Given the nice simple relationship between spin rate, radius, and
acceleration, it turns out that a 1-RPM structure giving a useful
fraction of 1G has to be *big*, hundreds of meters at least.  This
is a bit too big for timid NASA planners just now.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry