Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!snorkelwacker.mit.edu!hsdndev!husc6!purdue!mentor.cc.purdue.edu!mace.cc.purdue.edu!dil
From: dil@mace.cc.purdue.edu (Perry G Ramsey)
Newsgroups: sci.space.shuttle
Subject: Re:  Water dump...
Message-ID: <6451@mace.cc.purdue.edu>
Date: 20 Dec 90 17:17:41 GMT
References: <10212@jarthur.Claremont.EDU>
Reply-To: dil@mace.cc.purdue.edu (Perry G Ramsey)
Organization: Department of Earth and Atmospheric Sciences
Lines: 37

In article <10212@jarthur.Claremont.EDU> jdishaw@cbrown.claremont.edu writes:
>I know some of the water waste from the fuel cells gets reclaimed for use
>by the astronauts as their water supply and the rest gets dumped.  Why 
>don't they split the water back into hydrogen and oxygen and use it for
>the fuel cells again?  I know this isn't 100% efficient process, but I would
>think there would be some benefits.

Let me define a couple of terms, as they are used by the program:

Waste water:  Urine and condensed cabin humidity.  Unfit for human
consumption.

Potable water:  Water generated by the fuel cells.  It is suitable for
drinking.

What is going to be used to split the water molecules?  Electricity.
How are you going to generate it?  From combining hydrogen and oxygen in
the fuel cells!

The potable water generation rate is entirely a function of the
electricity generation rate.  By this I mean that there is more
water generated due to electrical requirements than can be used.
The only thing you can do is get rid of the excess water.

If you put some solar panels on the shuttle (something deployable
from the payload bay) you could use that electricity and reduce 
fuel cell useage in the first place.  Since cryogenic consumables
(liquid hydrogen and liquid oxygen to run the fuel cells) are the
current flight limiting factor, an extra source of electricity like
this could substantially extend the flight.

Unless you have a better idea on how to split water molecules.
-- 
Perry G. Ramsey           Department of Earth and Atmospheric Sciences
perryr@vm.cc.purdue.edu   Purdue University, W. Lafayette, IN USA
dil@mace.cc.purdue.edu   
 Why waste time learning when ignorance is instantaneous?  -- Hobbes