Soyuz and the Space Shuttle each docked with Mir and the International Space Station. When docked, the crew vehicle and station each share a common atmosphere for the crew to breathe. However, how did the atmospheres of these spacecraft compare (pressure, gas composition) when normally operated as individual spacecraft?



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All these craft were designed to maintain the rough equivalent of a sea level atmosphere.

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Reference: Life Support Concepts for Space Travel

Shuttle Environmental Control and Life Support System Mission Control Center screenshot from STS-88

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Reference: Personal notes

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Reference: Fundamentals of Aerospace Medicine

The Soyuz space ship uses an atmosphere of 21 % oxygen and 79 % nitrogen at a pressure of 1 bar, just like the ISS.

Reference: Emergency decompression of a Soyuz space ship and decompression sickness?

  • $\begingroup$ I really like that plot from Life Support Concepts for Space Travel. I can guess why some of those lines are important, but I'm wondering if there are specific concerns about the max N2 partial pressure and max O2 % inclined lines. I'm guessing that the O2 partial pressure is the main one that determines how well the lungs can oxygenate the blood, but does max O2 % have to do with combustion safety? Any idea why the max N2 partial pressure line at 11.6 psi is significant? Are these best asked as a new question? $\endgroup$
    – uhoh
    Apr 7, 2020 at 18:23
  • 2
    $\begingroup$ There is definitely a flammability concern at high O2 levels, and a new question would be great. $\endgroup$ Apr 7, 2020 at 18:52

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