Answers to: How have space suits dissipated the heat removed from astronauts? explain how USA suits currently use open-loop cooling.

Typically, space suits must dissipate several hundred watts of heat from the body of an EVAing astronaut.

The Apollo and Shuttle/ISS EVA suits used open-loop cooling by the sublimation of water into (near) vacuum, which introduced an additional consumable and is unworkable in an atmosphere.

Have any spacesuits been designed that use radiators (and presumably heat pumps) to dissipate heat? My calculations suggest that with a radiator temperature of ~ 500 K (227 deg C) you can get around 3.5 kW per square meter, which seems manageable.

  • $\begingroup$ But how do you get the radiator up to such drastic temperatures? You need some sort of heat pump/heat exchanger. $\endgroup$ Apr 24, 2020 at 11:14
  • $\begingroup$ but so maybe 600 K? $\endgroup$
    – uhoh
    Apr 24, 2020 at 11:59
  • $\begingroup$ I could have sworn this was asked already. $\endgroup$ Apr 24, 2020 at 13:07
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    $\begingroup$ As far as "design", there are plenty of "design"s. Just Google "spacesuit radiator" and click on any of the first 200 or so links. Did you mean "have been used before"? (In which case the answer is probably no. According to this report, NASA suits can radiate 2800 BTU/hr (820.6 W); a 37°C panel would need almost 2 square meters of space. This just isn't available on a spacesuit, so you need either a heat pump or open-cycle. You choose by picking the one that's passively safe—and now you see why one hasn't flown . . .) $\endgroup$
    – geometrian
    Apr 26, 2020 at 5:42
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    $\begingroup$ I mean, I can imagine problems existing, but it's kindof literally just a block of ice. To me, this seems simpler and less failure-prone than a heat pump—even a simple, miniaturized one. To be clear, I don't think such a solution is impossible (and it may even be a good idea given the value of volatiles at our current level of space development), but I think this is the reason why we have not seen it so far. $\endgroup$
    – geometrian
    Apr 26, 2020 at 8:49

1 Answer 1


During the service module spacewalk during Apollo 15-17, all three astronauts' spacesuits were connected by umbilicals to the command module. This included the closed-loop cooling water circuit, which dissipated heat using radiators on the service module.

(Technically answers the question, but perhaps not in the spirit of the question.)

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    $\begingroup$ Technically correct is the best kind of correct. $\endgroup$ Jul 22, 2021 at 18:40

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