Counter pressure spacesuits allow, in theory, a wearer to not be in an air tight space suit and work in a vacuum. What is the minimum such suit that could be used in a survival situation, on a ship, Mars or moon habitat?

I'm currently considering the insanity that the minimal solution is a low pressure breathing mask (5 psi oxygen), insulating shoes and a corset. Which is absurd. But you need counter pressure for the lungs to function... the floor/hull could be +/-100 degrees vs room temperature... and you need air. Everything else is optional, really, for 10 minutes survival time.

Or, to paraphrase, all you need is a corset, mask and high heels. Tell me how I'm wrong!

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    $\begingroup$ Some sort of rubber skintight suit can work in a pinch, for a short time. (Regular spacesuits are bulky mostly because of environmental control systems, first of all the need to keep the human cool. A human produces between 100 W (at rest) and 400 W (while doing hard physical work) of heat, and that heat must be taken care of, or else the human will overheat and die. Dissipating heat in a vacuum requires large radiators, which are rather impractical, so the suit comes with a heat exchange system and a heat sink.) $\endgroup$
    – AlexP
    Jan 24, 2020 at 23:00
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    $\begingroup$ Have you looked at the biosuit? It's really close to science-fact. If that's the kind of thing you're looking for, I can turn that into an answer. $\endgroup$
    – Cort Ammon
    Jan 25, 2020 at 5:50
  • $\begingroup$ The question came from discussion of the biosuit. Given a space/Mars location, what would constitute a 10 minutes emergency kit to move between domes or through broken ship sections. Then someone got silly with the corset and heels.... $\endgroup$ Jan 25, 2020 at 10:07
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    $\begingroup$ When you say 10 minutes survival time do you mean ten minutes of walking about and doing stuff or ten minutes until the person is clinically dead? Most experts agree that people are still recoverable after max. 3 minutes unprotected vacuum exposure. $\endgroup$
    – Dragongeek
    Jan 25, 2020 at 10:43
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    $\begingroup$ 10 minutes survival time, able to move from one Dome to another, or pass through a ship exposed to unplanned vacuum. Able to operate an airlock, open a door... but not do significant repairs. $\endgroup$ Jan 25, 2020 at 11:29

4 Answers 4


Or, to paraphrase, all you need is a corset,

A corset will provide mechanical counterpressure for your breathing, but there are a lot of other ways in which vacuum (or near-vacuum) exposure can hurt you that mean you need to cover up. Renan already referenced the main thing I was going to, which was Kittinger's hand. It didn't cause permanant damage, but it was repressurised swiftly. How much more pronounced the effects will be in a harder vacuum is probably unknown, but it seems reasonable to assume that exposed bodyparts will swell and bruise and be largely useless... without counterpressure on your hands, you won't be able to operate any sort of controls, for example.

And that was just his hand. There maybe other parts of your anatomy that you'd rather didn't suffer 100% bruising and traumatic swelling. Human skin is quite tough stuff, which is why people are unlikely to explode, Hollywood-style, on exposure to vacuum. There are numerous gaps in your skin though, allowing internal plumbing to communicate with the outside. Vacuum exposure to those, especially with any sort of counterpressure on the torso, may result in unpleasantness like your viscera extruding itself through the hole.

There's also stuff like aerogastralgia (something that's annoyingly poorly documented online, at least this side of a paywall) caused by air bubbles in the stomach and digestive tract expanding and causing pain (but rarely damage). Intense abdominal cramping is likely to hinder escape efforts. Kittinger had a special diet leading up to his high altitude jumps to reduce the probability of gas formation during digestion, but suitable lower-torso counterpressure should avoid this sort of issue.


Your mask will need to be well sealed against a ~one atmosphere pressure difference, and cover the eyes, nose and mouth. It'll need to seal well against dirty, sweaty skin and hair. This is at least just a simple matter of engineering, but it will be more like a hood than a mask by the time you're finished.

Failure to protect the eyes will probably result in at least temporary blindness, but there doesn't seem to be a lot of information of eye-vacuum exposure. The surface of the eye will dry out very quickly, and tears will rapidly boil away before performing any useful wetting, so the only thing the victim can do is keep their eyes tightly shut which will impair escape attempts.

Failure to protect the ears may result in ear damage, depending on how quickly pressure dropped and how sensibly the victim reacted. The Divers Alert Network has a whole section on ear barotrauma, none of which is good news. Effects like (possibly permananent) deafness probably won't bother them at the time, but inner ear damage can cause serious dizziness and vertigo which will definitely make any further escape attempts much harder. Eardum damage can also result in nausea and vomiting, so if that does occur and you don't have a good way to keep the breathing mask clear, the victim will drown in their own vomit.

and high heels.

Whatever floats your boat, but I haven't noticed those gracing the uniforms of any firefighters.

  • $\begingroup$ I grant that the expansion of human tissue without pressure is an issue, but the question is emergency survival, not comfortable long term use. It's plausible you'd want to throw in a pair of large gloves as well. User hands would expand to fill, but dexterity would remmain better than without. Agree that the mask would have to cover eyes and ears. They're not technically mandatory, just really USEFULL. Atmosphere would only have to be 5psi pure oxygen though. The heels...well, if I'm issuing everyone a corset anyway.... $\endgroup$ Jan 25, 2020 at 10:12
  • $\begingroup$ @user2702772 emergency survival requires you to be able to see, move and operate door handles or other emergency equipment. If you are blind, dizzy, in crippling pain and unable to operate your fingers (please re-read Kittinger's report on the matter, and remember that he was well equipped, well trained as was in a less stressful situation under higher pressure) then you will die. Its just that you'll die wearing high-heels and a corset instead. NTTIAWWT, but it ain't survival. $\endgroup$ Jan 25, 2020 at 12:10
  • $\begingroup$ Why blind and dizzy? I've accepted that both ears and eyes will beed to be kept at some level of pressure. Having re-read the report, I'd point out his issue was having no counter pressure on his hands. His gloves were designed with an inflatable bladder; without that, there was significant excess space leaving a badly shaped void. With correctly shaped gloves, you should be able to put them on, at pressure, and while your hands will expand to fit, provided the gloves can take the force they should provide required pressure. Also, setup assumes already in space, low pressure already $\endgroup$ Jan 25, 2020 at 12:52
  • $\begingroup$ @user2702772 if your hands are expanding then they will be painful and practically unusable. Just get some counterpressure gloves. This isn't hard. You'll be blind because the moisure in your corneas will evaporate drying your eyes out rapidly and painfully. You won't be able to keep them open, even assuming that they maintain their transparency as your tears boil off. You'll be dizzy for the reasons listed in my answer,with details given in the links. Damage to your inner and middle ears will disrupt your vestibular system. $\endgroup$ Jan 25, 2020 at 13:16
  • $\begingroup$ ...but I've agreed the mask would have to cover and provide presurised air to eyes and ears... $\endgroup$ Jan 25, 2020 at 15:40

"Tell me how I'm wrong!"

water ... you are made of it.

As pressure drops so does both the freezing and boiling point of water. Hard to know which is the concern or whether it would take 10 minutes to be a serious issue without knowing the temperature.

Also a fast enough rate of change in pressure may trigger nitrogen narcosis (the bends)

That's the reason why for example the "Honor Harrington" stories have ship crew and space workers in "skin suits" that seem to be half way between lycra and wetsuits when at risk.


  • $\begingroup$ They don't live in skin suits. They only put them on when the ship is to go into action. $\endgroup$
    – AlexP
    Jan 24, 2020 at 23:07
  • $\begingroup$ Skin is (quite usefully) watertight. So water boiling is only really an issue for the eyes... $\endgroup$
    – Joe Bloggs
    Jan 25, 2020 at 0:36
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    $\begingroup$ I assumed the survivor was a normal human with sweat glands and waste excretion organs, probably also hair follicles and microscopic imperfections such as scratches. Your skin may be a perfect two way barrier but mine has allowed the entry of various unpleasantness's when only knee deep in "no swimming" water. $\endgroup$
    – petera1289
    Jan 25, 2020 at 12:49

Your lungs are the result of us evolving to live at 1 atm. We can in theory survive in 0.33 atm, the pressure of the top of the Everest, for a few hours. We know this because a few crazy people climbed the Everest without oxygen tanks. But a handful lunatics doesn't represent a species, so let's just imagine that unless your protagonist is a mutant, you are dealing with a human who needs 1 atm of pressure.

The atmospheric pressure on the moon is for all practical purposes zero[citation needed], so your astronaut will face a pressure difference of one atm.

This is what happens when you have a solid object exposed to a pressure difference that is less than one:

Moob! The opposite of boom, get it?

Unless your astronaut is wearing a fully pressurized suit, the astronaut's lungs are going to do exactly like that tanker but in reverse (i.e.: the poor bugger's chest will blow up). Even if only a small part of the body is exposed, that part will suffer a lot. The first lunatic to ever become exposed to an atmospheric pressure of less than 0.1 atm was Joseph Kittinger, who rode some Air Force experimental balloons to higher than 20km up and then jumped with a parachute. In his third jump, the pressurization of his right hand glove failed and his hand doubled in size:

Incurring yet another equipment malfunction, the pressurization for his right glove malfunctioned during the ascent and his right hand swelled to twice its normal size

And that was just a minor malfunction, not a total one. I tried using a calculator to find out the atmospheric pressure at that altitude, but the calculator only goes up to 20,000m. For that altitude it gave me 0.05 atm. Kittinger was 50% higher than that when his hand depressurized.

There is no way you are going to be able to maintain a survivable internal pressure with anything less than an EVA suit. The ones that NASA used during the Apollo missions, like the A7LB suit, were rated for 6 or 7 hours of life support. To tone it down to 10 minutes, either say it is a prototype, a malfunctioning suit, or one that has already been used for a few hours.

Any other hack you use to try and survive in the hard vacuum of space is likely to not be able to provide the pressure your astronaut needs.

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    $\begingroup$ That tanker had much more surface area than a human chest, so it was experiencing a lot more force. 1atm of pressure is the same as you experience if you dive 30 feet underwater, which many people do (of course the pressure differential is the opposite way, so it's not really the best comparison). But even more than that, you don't actually need 1atm for your gas-- all that matters is the partial pressure of oxygen, which is why spacesuits use pure oxygen supplies at about 0.3 atm already. There are concepts for non pressurized space suits out there--look up mechanical counterpressure suits. $\endgroup$ Jan 25, 2020 at 7:17
  • $\begingroup$ @elduderino if you go from x atm to x - 1 atm in little time you risk internal lesions and death. Im the OP case it seems like the protagonost is going for an immediate change, since I see no way to go from 1 atm to 0 on the surface of the Moon. Also the point about surface area of the tanker is moot - atmospheric pressure is practically the same over the whole tanker, i.e.: esch square inch of the tanker is subject to the same pressure as each square inch of a person. $\endgroup$ Jan 25, 2020 at 14:43
  • $\begingroup$ I'm sure that if the external pressure changed very rapidly, you would experience troubles. But my interpretation of the question is that the suit could be used if you need to get from one pressurized vessel to another by crossing a vacuum, in which case you should have airlocks available for gradual decompression. And even if you were using the suit because you were in a vessel which sprung a leak and started to decompress, it would still be a slow process unless the leak was extremely big. As for the point about the tanker-- I don't think it's moot ... $\endgroup$ Jan 25, 2020 at 15:29
  • $\begingroup$ (cont) The way strength vs surface area scales as you change the size of objects makes it easier to design small objects that are under high pressures. Example: I do research in ICF and we regularly use these 1mm radius capsules with plastic walls that are only ~20 microns thick, and are pressurized to 20 atm! But even more importantly, mechanical counter pressure suits are a thing that have been successfully vacuum tested by NASA, so you don't have to take my word for it. $\endgroup$ Jan 25, 2020 at 15:35

Low pressure breathing masks won’t work. In a vacuum all air will be sucked out of the lungs and out of the breathing mask. The person would be unconscious in less than 30 seconds and dead in a few minutes.

To survive for 10 minutes a pressurised atmosphere would be needed. I suggest that a sealable, inflatable sphere made of a robust plastic material 1m in diameter would be sufficient to keep someone alive for 10 minutes in an emergency. There would be sufficient oxygen and sufficient pressure.

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    $\begingroup$ Why would all the air be sucked out of the breathing mask and lungs? As long as the seal for the mask is sufficiently robust (admittedly easier said than done) I don't think this would be an issue. $\endgroup$ Jan 25, 2020 at 7:24
  • $\begingroup$ @el duderino It certainly would be easier said than done. Perhaps blown out would be a better description. Gases will expand into a vacuum and with vacuum all around the air in someones lungs would force itself out. Imagine swallowing a bottle of very fizzy Coke very quickly perhaps with a minto and trying to prevent that very mild gas pressure from exerting itself. $\endgroup$
    – Slarty
    Jan 25, 2020 at 10:51
  • $\begingroup$ The difference between your example and mechanical counter pressure suits is that 1) the stomach isn't as robust against pressure differentials as the lungs are, and 2) in that example you're trying to hold the higher pressure in by closing your mouth, something there's no need for if you have a helmet/mask on pressurized to the same level. Mechanical counter pressure suits have been tested before at vacuum so it's not a fictional concept-- although the tested suits used helmets, not masks (which is probably the only feasible way to get a good seal and protect the eyes/ears). $\endgroup$ Jan 25, 2020 at 15:52

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