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Life support?

  1. Jan 17, 2008 #1
    What exactly is life support? Is it somthing on the shuttle or in their suites? Is it just somthing to recreat the environment of Earth? Please can some one elaborate?
     
  2. jcsd
  3. Jan 17, 2008 #2

    mgb_phys

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    It's the general term given to all the stuff that keeps you alive!
    The pressure, oxygen, temperature, CO2 removal etc.
     
  4. Jan 17, 2008 #3
    ok so then it would be in both the suite and shuttle. Now why must CO2 be removed? I mean thats really (except for the 1% [including carbon] of other gases we breath) what we breath in, on this world? So i mean whats so bad about it if this compound has oxygen?
     
    Last edited: Jan 17, 2008
  5. Jan 17, 2008 #4

    mgb_phys

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    CO2 is about 0.03% of air but it is toxic at about 5% (about the same concentration as you breathing out) - ifyou don't remeove it from the air it eventually kills you.
    CO2 controls your breathing and blood acidity among other things.

    YOu can breath in either air or pure oxygen, the only thing you NEED is O2, butthe rest of the air just has to not have anything toxic. Early US capsules used pure O2 but it was a nasty fire risk, modern craft use air and add extra oxygen from tanks as it used up while at the same time removing CO2.

    The shuttle flies with a shirt sleeves atmosphere, you don't need a suit inside it, the suit backpack basically contains smaller versions of the shuttle life support systems.
    A submarine or a scuba diving rebreather is a similair system.
     
    Last edited: Jan 18, 2008
  6. Jan 18, 2008 #5

    russ_watters

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    You may also consider the systems on board that assist other bodily functions to be "life support" systems as well...
     
  7. Jan 18, 2008 #6

    Janus

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    Not quite. While the Shuttle uses a nitrogen-oxygen mix at 1 atm, the suits still use pure oxygen at 4.3 lb/in².

    This leads to one drawback. Since the astronauts are breathing a nitrogen-oxygen mix in the shuttle, they have nitrogen disolved in their blood. If they were to go directly to the lower pressure of the suit, the nitrogen would bubble out and they'd get the "bends".

    To get around this, an astronaut planning to go EVA has to breathe pure oxygen from a portable unit for 2.5 hrs prior to donning his suit. This flushes the nitrogen out of his blood.
     
  8. Jan 18, 2008 #7

    mgb_phys

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    Interesting - presumably to reduce the pressure load on the suit and stop it doing a 'michelin man', I suppose there isn't much fire risk inside a suit.
     
  9. Jan 18, 2008 #8

    russ_watters

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    Fire risk is dependent on [partial] pressure, so it is greatly reduced by the reduced pressure. That's what makes the error that led to the Apollo 1 fire all the more idiotic. It was acutally pressurized - above atmospheric pressure, with pure oxygen. All sorts of normally benign things become flammable under those conditions.
     
  10. Jan 18, 2008 #9

    mgb_phys

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    Really! I had always assumed the Mercury capsules were run at near 0.21bar and 100% O2 to reduce the mechanical stress while giving a normal ppO2.
    Apart from the fire risk, there is a danger of a CNS hit if you are highly physically stressed at high O2 partial pressures.
     
  11. Jan 24, 2008 #10
    wow thats alot of stuff that i really wanta learn but i dont curntly. lol. what sciences do you learn that stuff in?
     
  12. Jan 25, 2008 #11

    mgb_phys

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    I'm an astronomer and diving instructor.
     
  13. Jan 28, 2008 #12
    then you could really help me in my WAS program, right?
     
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