How effective is the thermal control system and the liquid cooling garment of a space suit? Does it prevent sweating only for a small to medium workload? If an astronaut is sweating behind his ears there might be problems with the communication system inside the helmet and the vision might be impaired. Wearing a suit filled with some sweat for many hours during an EVA might be uncomfortable.

  • $\begingroup$ Any specific suit you are considering ? Only current generation ? Including reentry suit ? $\endgroup$ – Antzi Sep 23 '16 at 10:29
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    $\begingroup$ Of course they do. And it's a simple Google search. E.g. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690025333.pdf $\endgroup$ – user10509 Sep 23 '16 at 11:16
  • $\begingroup$ Humidity of - and water removal from the air is important factor. You can sweat plenty in dry air and not realize it and remain dry until you see the salt building up on your clothes and even skin. $\endgroup$ – uhoh Sep 26 '16 at 10:02

While I don't have a source document I can link, from talking with folks in the JSC suit lab, I have learned that in general, the EMU (ISS/shuttle space suit) cooling system is overpowered to a small degree, to the point that crew can become uncomfortably cold while working.

The suit does have a valve that allows crew to adjust the cooling rate. It's labeled on the right side of the picture below. Interestingly, most astronauts tend not to use that valve for the fine-grained control for which it was designed -- they just tend to flip it all the way to "C" when they get too hot and all the way to "H" when they get too cold. (again, no documented source -- just from conversations I've had)

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  • $\begingroup$ Well, I suppose that in the middle of an EVA is not the ideal time to fiddle unnecessarily with the controls. I can certainly understand why there might be a preference to just make it easy. $\endgroup$ – user Sep 26 '16 at 16:51
  • $\begingroup$ And now I've got the idea in my head of an astronaut hitting the PTT and saying "I'm hot, guys... let me just chill for a while" during a multi-astronaut EVA. Or hopefully not. $\endgroup$ – user Sep 26 '16 at 16:51

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