Hacker News new | past | comments | ask | show | jobs | submit login
How would the unprotected human body react to the vacuum of outer space? (nasa.gov)
128 points by usaphp on Aug 16, 2013 | hide | past | web | favorite | 61 comments

2001: A Space Odyssey (the movie) got this right almost half a century ago. Bowman briefly exposed himself to space trying to return to the ship for the showdown with Hal. The only movie mistake was something Clarke later claimed would never have happened had he been on set that day: Bowman is seen apparently taking a deep breath before opening the pod door.

Edit: Found the scene: http://www.youtube.com/watch?feature=player_detailpage&v=0Nb...

The only movie mistake was something Clarke later claimed would never have happened had he been on set that day: Bowman is seen apparently taking a deep breath before opening the pod door.

Hah, I thought that was just a tick. You would take a breath before doing any hard physical effort and I'm pretty sure you'd try to do it even in the vacuum of space just because you're used to.

I always assumed he was hyperventilating to get as much oxygen as possible in his blood before the jump. He would have to let the air out of his lungs before jumping but I never felt like anything in the scene contradicted that.

Hyperventilating actually reduces the amount of CO2 in the body, a build up of CO2 is what creates the need to take a breath. (One of the few things I remember from scuba diving).

Thanks. That still kind of validates the impression I had that hyperventilating wasn't an irrational thing for him to be doing, but it's a very different thing.

The interesting thing is that Arthur C. Clarke was a very experienced scuba diver and still had a problem with the scene. Ah well.

It's one of my favorite action scenes in any science fiction film. The interesting thing is that the trick just relied on good photography, piano wire and dropping Keir Dullea. It's easy to imagine how a present-day director would mess that scene up with CGI effects, slow-motion, stuntmen, and so on.

Can't edit: It seems I just completely misremembered the previous part of that scene. I thought he was already in vacuum and pulling on the door to get in.

What this article leads me to think is that, if we managed to create a thin elastic tight-fitting suit that compressed the body with the equivalent pressure of Earth's atmosphere, the issues with lung overpressure would be negated and we could, ignoring radiation and temperature issues, just be in space with scuba gear.

That would be awesome.


There are a lot of advantages to this idea, but it is not without tradeoffs. For example, for these sorts of suits to work properly they need to be in contact with all of your body. Any gap, between your toes or your legs... and you will have problems. This can be overcome but you basically end up having to tailor each suit to a particular astronaut. The suits currently used on the ISS are not specially tailored, they basically just have "small/medium/large" (though they have a greater variety of sizes for gloves).

Cooling is actually a major issue with this idea. Working in space your going to encounter a huge temperature range so you want a fair amount of insulation, but dumping heat to the vacuume of space is much harder than cooling off on a hot day so current suits use an environmental control suystem to cool as needed.

> dumping heat to the vacuume of space is much harder than cooling off on a hot day

Is it? A naive application of the Stefan–Boltzmann law yields a loss of about 1 kW through heat radiation alone.

"Have Spacesuit, Will Travel" by Heinlein mentioned this -- I remember as a kid I hadn't understood it.

Maybe some sort of spray-on rubber that cures on contact with air? You'd get naked, put on your helmet and enter the spray-chamber that will coat your body thickly and evenly.

Seems plausible. You might need a rubber that "cures tight" though, I'm not sure.

oh man, can we get this for regular daily Earthling use as well!?

What for, beside fetishistic reasons? (and those, ALREADY have this technology... sex technology advance faster than many people can imagine)

Your shower could dress you!


Hmm, interesting idea. You might actually be able to make quick super-light one-time use spacesuits like that.

Mechanical compression suits are lighter than pressure suits in the first place (in addition to being less bulky), so having every astronaut bring along their own might not be too unreasonable now that I think about it. More labor with the tailoring bit, but not if you heatshrink them...

One possible problem is the 'sunburn' aspect, heatshrink tends to want to shrink more the longer you heat it. So being exposed to direct sunlight might cause you to get squeezed. Maybe there is a way to limit the amount of inward pressure that the heatshrink would create.

You may be able to get around that with a loose-fitting mylar (or similar) outer-garment.

I think that the Space Activity Suit project proposed that you would wear an extra loose layer over the top to provide some micrometeorite protection.

I should try this, I have some pretty large diameter heatshrink lying around in a warehouse, next time I'm there I will bring it with me.

Better try it on some sausage or a (dead) chicken first :)

Yes, please try it on food first... that might be a hard one to explain at the hospital if it goes wrong. :P

And how Hollywood thinks about this:


(The scene where Cohagen gets exposed to the martian atmosphere and dies).

I'm not sure if that's better or worse than Event Horizon (exploding eyes anyone?)


At least in both of those the victim stays alive for a while. In Red Planet^W^W Mission to Mars somebody removes their helmet and instantly turns meat-popsicle.

I love the NASA study in the 1960's that addressed this, if only for the title:


    Eight chimpanzees, used in nine separate tests, were
    decompressed from 179 mm Hg (100% oxygen) to less than
    2mm Hg in 0.8 seconds and remained at this altitude from
    5 to 150 seconds. 

    All subjects showed slight neutrophilia, increased
    transaminase, and facial edema which returned to normal
    within 72 hours after decompression. All subjects survived
    in good health and no lasting effects of rapid decompression
    to a near vacuum could be detected. 
Implications for the hyperloop as well.

[1] - http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=ht...


I like this article much better. Covers more topics with more detail.

Well that ruined the end of "Total Recall"

The end of "Total Recall" ruined "Total Recall".

Sunburn wasn't my first thought, but I guess it makes sense. Love the down-to-earth tone of the article.

"The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil"

Can someone explain the boiling water on his tongue?

"Boiling" is really a liquid turning into a gas [1]. This happens when the liquid has enough energy to transition into a different state [2], that is, when the vapor pressure of the liquid [3][4] equals the surrounding pressure. Thus at the pressure given in the article (say, 0.5 psi), water can boil at around 79.6 °F / 26.4 °C [5].

[1] http://en.wikipedia.org/wiki/Boiling_point

[2] http://en.wikipedia.org/wiki/Heat_of_vaporization

[3] http://en.wikipedia.org/wiki/Vapor_pressure

[4] A solid can "boil" too, but it's called sublimation. http://en.wikipedia.org/wiki/Sublimation_(physics)

[5] http://www.engineeringtoolbox.com/boiling-point-water-d_926....

> Can someone explain the boiling water on his tongue?

The main thing stopping the molecules of a liquid boiling away (flying off, out of the container) is the pressure exerted by the gas above or around them.

If you make the liquid molecules move faster (i.e. give them energy, i.e. heat them up), a greater proportion of them will be able to overcome this pressure. So heating increases evaporation and leads to boiling - which we're familiar with.

Alternatively, if you reduce the pressure of the gas pushing the liquid molecules together, you don't need to heat up the liquid as much to get the same evaporation/boiling effect.

Reduce the gas pressure enough and the liquid will boil at a very low temperature.

Ah, now I understand how pressure cookers work

In a vacuum, water will promptly vaporize at virtually any temperature.

If you're not supposed to hold your breath, what happens? It makes as much sense to me as not holding your breath under water (not using scuba gear, snorkel). Otherwise, good to know you can transfer to safety from a sabotaged space wreck with a psychotic robot, no special gear required.

I think the lungs aren't strong enough to act as a pressure vessel against the vacuum. Trying to hold it in is like expecting your sensitive tissues to behave the same as a scuba tank.

If you don't hold it in, the air will simply leave your lungs and you have about 12-15 seconds before the remaining oxygen in your blood leaves your body making you unconscious. The lungs, instead of trading CO2 for O2 is now working in reverse in the vacuum, exchanging O2 for... nothing. That amount of time should be enough for you to reattach your O2 hose and open the airlock etc.

I also recall reading somewhere that you may urinate, defecate and projectile vomit simultaneously after a while, however by that time, you may already be unconscious.

You are correct. You can simulate this by filling your lungs with air at 10 m under water and then rise quickly to the surface while holding your breath. It would be analog to filling your lungs with 2atm at sea level. Boom.

Ah, I'm gonna have to take your word for it ;)

The diving comparison comes up a lot with these space exposure questions. Even the article mentions Scuba diving. But diving is applicable in many ways not just in terms of physiology, but behavior and psychology as well.

I remember there was once also an experiment in an undersea lab where a group of people spent time to see what would happen on similar long duration space missions.

Diving comparisons can actually give us real-world examples of Hollywood style decompression too. In real life human bodies don't explode when decompressed in space, but if you depressurize a diving bell on the surface then all bets are off: http://en.wikipedia.org/wiki/Byford_Dolphin#Diving_bell_acci...

1atm->0atm won't do it, but apparently 9atm->1atm can.

Mythbusters did something similar. They tested what would happen to a diver if you cut the hose in one of those old-school diving suits that had a hose connecting them to the surface. It's not pretty: http://www.youtube.com/watch?v=LEY3fN4N3D8

Pressure differentials are powerful.

That's one of the most horrifying things I've ever read. I thank you for the lesson; not so much for the nightmares.

I always figured that you wouldn't explode, but simply 'disassemble'. It was my understanding that the human body is held together under of the pressure of the atmosphere. So, if you remove the atmosphere, what is holding the body together?

Mount Everest is 1/3 sea level pressure and while you can't breath up there your not at risk of poping. The reason for this is a combination of things, the skin is tough stuff, but also your insides also resist expansion. Down to the cellular level where osmotic forces can be stronger than a pure vacuume.

Space Suit Testing - The instantaneous effects on a human when exposed to near-vacuum conditions


That's from the six-part series Moon Machines. It's a great look at the research and scientific work that went into the Apollo lunar program, and the focus is on the men and women behind the scenes, rather than the astronauts and other people at NASA. Well worth watching if the lunar program is a subject of interest.


It would be interesting to hear what would happen if you had an emergency oxygen supply, like one of those miniature scuba tanks. How would that change the survival range?

Breathing pressurized air in vacuum is not such a good idea.

Pure oxygen at low pressure might actually work. I'm pretty sure the lungs can take 0.1 atm pressure differential, and it should be enough oxygen to stay conscious indefinitely.

The numbers I found were that people can blow about 1-2 PSI (obtained by random people on the internet blowing into their scuba gauges), which implies that you could probably handle at least 0.07-0.14 atmospheres of positive pressure in your lungs without exploding.

The peak of Mount Everest is about 1/3 atmosphere, and base camp is in about 1/2 atmosphere. This means the partial pressure of oxygen at those locations is about 0.07 and 0.1 atmospheres, respectively. People who have not acclimated to high altitudes (by spending 2 months at base camp) will pass out on the peak (and it still sucks pretty hard even if you're acclimated).

So, it seems like pure oxygen at 0.1 atmosphere should work, although I suspect it'd be hella uncomfortable even without the vacuum, since it'd probably feel like you were trying to blow up the worlds largest balloon while standing on Mount Everest.

But it does let us move on. So you're standing in a vacuum (on the Moon, maybe) sucking on 0.1 atmosphere of pure oxygen. How long can you survive for?

That's what's interesting to me - the emergency scenario where the oxygen situation is (uncomfortable but) survivable. How long would it take for the exposure to kill you?

Didn't we just have an article about a liquid, injectable oxygen for emergency medical use? How about skipping the lungs as O2 input, keep them just for CO2 removal, and take an IV containing the liquid oxygenator?

You might need to keep a small amount of lung pressure (say, less than that used to blow up party balloons) to slow the egress of oxygen through the lungs.

The next problem is likely that your lungs catch fire as the O2 concentration builds up in them. One thing at a time though.

You'd probably injure yourself with an air tank. I wonder if hyperventilating yourself before exposure would help though.

I think it wouldn't. I believe your lungs in a vacuum will de-oxygenate your blood regardless, so you only have as much time as it takes for that blood to hit your brain.

Hyperventilating is good for removing CO2 from your blood, which reduces your "I really need to breath" reflex (turns out that is, at least largely, cause by the presence of CO2 rather than the absence of O2). From personal experience I can tell you this can allow you to push yourself further without breathing, but you also run the risk of blacking out because you pushed too far (I don't have experience with that part).

I find myself much more interested in space now than ever been (as an adult) and I can directly attribute that to the work Elon Musk has been doing. I wonder if he's shaping the next generation of entrapreneurs and startups.

gives 404 error


Please read the article.

It's still badly. You get sunburned, lose consciousness due to lack of oxygen and die.

In case of problems, 10-14 seconds is a lot of time.

Registration is open for Startup School 2019. Classes start July 22nd.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact