Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!henry 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