A few days ago a question was asked on Reddit whether or not a human could survive in space with "just enough" of a spacesuit to plug all the important holes, e.g. a face mask to plug the eyes, ears, nose and mouth, and some kind of special underwear that maintains pressure in the nethers. The astronaut would effectively be their own space suit.

The popular answer was that the astronaut's lungs would explode due to a lack of external pressure, however I'm struggling with the logic.

Based on everything I've read about how a human would cope in space with no spacesuit at all, e.g., their fluids wouldn't boil because the skin maintains an effective pressure barrier, and the fact that there must be some quantity of air in the thoracic cavity (i.e., outside the lungs but inside the chest), then supposing that this mask provides ~1 atm pressure, would it not be the case that they would be fine so long as their chest is sealed? In this scenario the pressure in the thoracic cavity would reach an equilibrium with the elasticity of the chest wall at somewhere less than 1 atm (Boyle's Law); if the astronaut is supplied air at roughly the equilibrium pressure then then my guess is that breathing shouldn't be a problem, but being off by too much would pop or collapse the lungs. As far as I know, the thoracic cavity is airtight, and this assumes the chest can withstand a ~1 atm pressure differential.

So is it possible to survive in space this way, at least in the scale of ~10-20 minutes? As in, the pressure differentials wouldn't cause your chest or lungs to explode, implode, or make it otherwise impossible to breathe?

This is of course ignoring all the other perils of being naked in space.

  • 3
    $\begingroup$ Possibly the same type question: physics.stackexchange.com/q/3076 esp. The second answer re: the vacuum chamber $\endgroup$
    – user81619
    Oct 30, 2015 at 18:55
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    $\begingroup$ There has been speculation (mostly in SF) about using elastic body suit to control the discomfort of maintaining the body at an atmosphere in a hard vacuum. Once $\mathrm{O}_2$ is assured the next major challenge is thermal regulation. $\endgroup$ Oct 30, 2015 at 18:57
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    $\begingroup$ The differential of ~ 14 psi would push the diaphragm into the abdominal cavity causing the belly to distend, and the diaphragmatic muscles would be unable to push gas from the lungs and probably rupture them from beneath.You might be able to get away with decreasing the breathing pressure to ~ 8 psi, but much lower than that you won't have the tension you need to move O2 into the capillaries. An equivalent experiment would be to pressurize your lungs to 14 psig at the standard atmosphere. I suggest you not try to do that! $\endgroup$
    – docscience
    Oct 30, 2015 at 19:27
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    $\begingroup$ @docscience: Thumbs up, but the $O_2$ partial pressure at normal conditions is only 3psi and one could probably survive for some time on a partial pressure of 2psi, even though I still don't think that a human diaphragm would be happy with that... where do the 8psi come from? Just curious. $\endgroup$
    – CuriousOne
    Oct 30, 2015 at 19:38
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    $\begingroup$ I'm voting to close this question as off-topic because it is asking for speculations about the survival of a person in an extreme environment and not physics. $\endgroup$
    – Kyle Kanos
    Oct 30, 2015 at 19:43


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