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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.sci,net.space
Subject: Re: Would a candle burn ...
Message-ID: <5862@utzoo.UUCP>
Date: Fri, 2-Aug-85 15:04:44 EDT
Article-I.D.: utzoo.5862
Posted: Fri Aug  2 15:04:44 1985
Date-Received: Fri, 2-Aug-85 15:04:44 EDT
References: <53@ssc-vax.UUCP> <1273@utcsri.UUCP> <534@leadsv.UUCP>
Organization: U of Toronto Zoology
Lines: 18

> >Uh, wrong.  The atmosphere is far from 100% O2.  Remember the
> >accident that killed four astronauts?  That was the last time
> >pure O2 was used, and that was many years ago.
> 
>     That was the last time O2 was used at full atmospheric pressure.
> I had been under the impression that afterwards, on launch they
> used 80% nitrogen & 20% oxygen. The mixture then reduced to pure
> oxygen at much lower pressure during boost phase.

More specifically, the Apollo flights all started out with the cabin
full of 80/20 mix and the astronauts breathing pure oxygen (through
either oxygen masks or their spacesuits, not sure which).  The cabin
atmosphere changed to pure oxygen during boost.  The astronauts had
to be breathing pure oxygen from the start to avoid decompression
problems.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry