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From: jonkatz@gn.ecn.purdue.edu (Jonathan W. Katz)
Newsgroups: sci.space.shuttle
Subject: Re: Definition of "APU"
Message-ID: <1991Apr14.160830.18553@gn.ecn.purdue.edu>
Date: 14 Apr 91 16:08:30 GMT
References: <3331@beguine.UUCP>
Organization: Purdue University Engineering Computer Network
Lines: 12

In article <3331@beguine.UUCP> Tom.Hocking@bbs.acs.unc.edu (Tom Hocking) writes:
>
>According to my list of NASA Acronyms, APU stands for "Auxiliary Power
>Unit."  However, the shuttle needs them to generate power any time the
>orbiter is not attached to umbilicals.	
>
>--

That's not quite true.  The APU's are needed during ascent and descent to 
power the hydraulic systems.  The orbiter gets the majority of its electrical
power from three fuel cells that convert hydrogen and oxygen to 
electricity and water.