What sort of spacesuit would an astronaut need if she were to walk on a planet with a 1 psi (0.07 ATM) 100% methane atmosphere and -60°F (-50°C) temperatures?

  • $\begingroup$ Possible duplicate of Current state of the art Mars spacesuit? $\endgroup$
    – Antzi
    Commented Nov 29, 2018 at 4:56
  • $\begingroup$ @Antzi: Not really a dupe. Mars has no pressure to speak of, so a Mars suit needs less insulation and more skin pressure than this presumably would. $\endgroup$ Commented Nov 29, 2018 at 5:49
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    $\begingroup$ Oh dear… yet another user of that name. It's the same name as was used for the repeated "helmet on Mars" questions that were asked (and all closed) lately. $\endgroup$
    – DarkDust
    Commented Nov 29, 2018 at 7:59
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    $\begingroup$ @DarkDust: I thought the same thing. However, let's consider this on its merits as a question, not on the person posting it. It looks to me as a valid question. Uwe's answer is good. I'm about to do a tag edit to clean up the tags. $\endgroup$
    – DrSheldon
    Commented Nov 29, 2018 at 14:03
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    $\begingroup$ One interesting question is whether that much cold methane is enough (a) to get rid of the heat produced by the suit and its occupant (a big problem on Mars, for instance) (b) enough to provide a significant cold problem, requiring extra active heating or insulation in the suit. $\endgroup$ Commented Nov 29, 2018 at 17:33

1 Answer 1


A pressurized space suit is needed when the atmospheric pressure is lower than about 0.3 to 0.4 bar. Pure oxygen is breathed within the suit. So for about 0.07 bar a pressurized suit is mandatory.

But a flammable or explosive mixture within the airlock needed to leave and reenter the planet lander should be avoided. So the airlock should be evacuated from methane before filling it with a breathable atmosphere. The methane is thus moved back from the airlock to the planets atmosphere.

To minimize loss of atmosphere, the airlock may be evacuated using the pump to move the air from airlock into the planet lander.

  • $\begingroup$ The airlock would be a very big problem. since the atmosphere is 100% methane, the base will have to lose atmosphere every time it cycles the lock. Even if you burn methane in a controlled manner to generate the blow-out gas, you will still be using oxygen. $\endgroup$
    – ShadoCat
    Commented Nov 29, 2018 at 18:32
  • $\begingroup$ It would also be wise to build the suit as to not build up a static charge. Any suit leak combined with the methane atmosphere and a spark could be very dangerous. $\endgroup$
    – Dragongeek
    Commented Nov 29, 2018 at 21:32
  • $\begingroup$ A substantial suit leak is very dangerous anyway. But a mix of very much methane with very few oxygen outside the suit would be neither ignitable nor explosive. There is so much methane outside the suit and so few oxygen leaking from the suit that an explosive mixture is very unlikely. $\endgroup$
    – Uwe
    Commented Nov 29, 2018 at 21:40
  • $\begingroup$ The airlock loss of atmosphere will depend on airlock volume and pressure only, but not on the planets methane atmosphere and pressure. You will loose the same amount of atmosphere in a vacuum or in the methane atmosphere. $\endgroup$
    – Uwe
    Commented Nov 29, 2018 at 21:48

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