At 08:31 PM 11/8/02, Robert Seeberger wrote:
----- Original Message ----- From: "Ronn Blankenship" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, November 08, 2002 5:16 PM Subject: Re: Space Pen versus Pencil, was Scouted: Fireworks> astronauts and (2) perhaps getting into the electronic equipment and > causing short circuits (graphite being a conductor) or sparks, which would > have been fatal in the pure oxygen atmosphere used prior to the Apollo 1 fire. > > Isnt "pure oxygen" poisonous? Not to mention extremely corrosive? I hear this a lot, especially from divers, but it is my understanding that "pure oxygen" would burn your lungs and kill you quickly. Isnt it actually the "highest tolerable oxygen content atmosphere" that people mean when they make this kind of statement?
Prior to Apollo 1, NASA used pure oxygen at about 3 psi, which is basically the same amount of oxygen in ordinary air at sea level (20% of 15 psi), for two reasons: (1) to mix it with anything else means you have to take along a supply of that other gas, which adds weight, and (2) with the pressure changes involved in depressurizing and repressurizing the cabin, a nitrogen-oxygen mix would carry a risk of the bends for the astronauts. Then the Apollo 1 fire occurred, probably as a result of an electrical spark in the cabin which caused everything remotely flammable to burn in the pure oxygen atmosphere. Part of the redesign involved provision of a helium-oxygen mix which would not support runaway combustion like pure oxygen and would not lead to the bends.
-- Ronn! :)
Ronn Blankenship
Instructor of Astronomy/Planetary Science
University of Montevallo
Montevallo, AL
Disclaimer: Unless specifically stated otherwise, any opinions contained herein are the personal opinions of the author and do not represent the official position of the University of Montevallo.
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