

How would the unprotected human body react to the vacuum of outer space? - usaphp
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

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dalek_cannes
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...](http://www.youtube.com/watch?feature=player_detailpage&v=0NbkF9_T0Eg&t=490)

~~~
anonymous
_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.

~~~
justin66
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.

~~~
jimbobjim
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).

~~~
justin66
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.

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adlpz
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.

~~~
jlgreco
[http://en.wikipedia.org/wiki/Space_activity_suit](http://en.wikipedia.org/wiki/Space_activity_suit)

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).

~~~
Retric
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.

~~~
brazzy
> 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.

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Luyt
And how Hollywood thinks about this:

[http://www.youtube.com/watch?v=8f0iDL3pAhE](http://www.youtube.com/watch?v=8f0iDL3pAhE)

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

~~~
jbigelow76
I'm not sure if that's better or worse than Event Horizon (exploding eyes
anyone?)

[http://www.youtube.com/watch?v=3LEa0FN1bf8](http://www.youtube.com/watch?v=3LEa0FN1bf8)

~~~
jlgreco
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.

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

"THE EFFECT ON THE CHIMPANZEE OF RAPID DECOMPRESSION TO A NEAR VACUUM."

    
    
        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...](http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0479738)

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HanyouHottie
[http://www.geoffreylandis.com/vacuum.html](http://www.geoffreylandis.com/vacuum.html)

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

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speedyrev
Well that ruined the end of "Total Recall"

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

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

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gregman
"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?

~~~
jbert
> 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.

~~~
cheapsteak
Ah, now I understand how pressure cookers work

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bch
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.

~~~
eksith
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.

~~~
torstesu
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.

~~~
eksith
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.

~~~
jlgreco
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...](http://en.wikipedia.org/wiki/Byford_Dolphin#Diving_bell_accident)

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

~~~
scott_s
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](http://www.youtube.com/watch?v=LEY3fN4N3D8)

Pressure differentials are powerful.

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rlt3
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?

~~~
Retric
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.

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

[http://www.youtube.com/watch?v=KO8L9tKR4CY](http://www.youtube.com/watch?v=KO8L9tKR4CY)

~~~
NaOH
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.

[http://www.amazon.com/Moon-Machines-Robert-
Seamans/dp/B0026I...](http://www.amazon.com/Moon-Machines-Robert-
Seamans/dp/B0026IQTR2/)

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wikiburner
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?

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

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brazzy
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.

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saalweachter
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?

~~~
wikiburner
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?

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louhong
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.

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cad
gives 404 error

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patmcc
Badly.

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frozenport
Please read the article.

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

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

