How long can a human live unprotected in space?

[editor]

I've always wondered about this, so I'm chuffed to see that NASA has provided the answer:

How long can a human live unprotected in space?

If you don't try to hold your breath, exposure to space for half a minute or so is unlikely to produce permanent injury. Holding your breath is likely to damage your lungs, something scuba divers have to watch out for when ascending, and you'll have eardrum trouble if your Eustachian tubes are badly plugged up, but theory predicts -- and animal experiments confirm -- that otherwise, exposure to vacuum causes no immediate injury. You do not explode.

Your blood does not boil. You do not freeze. You do not instantly lose consciousness.

Various minor problems (sunburn, possibly "the bends", certainly some [mild, reversible, painless] swelling of skin and underlying tissue) start after ten seconds or so. At some point you lose consciousness from lack of oxygen. Injuries accumulate. After perhaps one or two minutes, you're dying. The limits are not really known.

You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly.

Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.

At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain.

The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. 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.

More: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

 

[editor]

More here: http://www.geoffreylandis.com/vacuum.html

 

[weltweit]

Yes, that is pretty much what I would expect, the problem is lack of oxygen.

Still won't affect me.

I love my planet

I love my people

I will never leave them for space!

 

[editor]

I always thought that humans exploded in a dramatic fashion.

 

[weltweit]

I always thought that humans exploded in a dramatic fashion.

From the reduction in pressure, yes I suppose that is a realistic thought..

Don't deep sea fish when they are brought up to the surface expand ... (a lot) ?

 

[dylanredefined]

Yeah which kills them unfortunately its the cells that explode to a degree rather than the entire fish.People don't die by explosion the film sunshine showed grisly death in vacuum.

 

[EastEnder]

Don't deep sea fish when they are brought up to the surface expand ... (a lot) ?

Their swim bladders have a tendency to go pop....

A volume of liquid encased in a flexible membrane (which is essentially what we are) does not react dramatically to pressure changes. Liquids are essentially incompressible (apart from at very extreme pressures), which is why hydraulic systems work - you wouldn't want a compressible liquid in your car's brake lines. So it therefore follows, that if the liquid in a given volume at one atmosphere has not been compressed, why would it expand when the pressure drops to nothing? No expansion, no change in size, equals no explosion.

Gasses, on the other hand, are much more entertaining when subjected to big changes in pressure. If you do unexpectedly find yourself in a hard vacuum, don't hold your breath, don't try to keep farts in (this is no time for manners) and pray you've got decent fillings - if the dentist trapped any air bubbles under the amalgam, they're about to get a whole lot bigger...

 

[HAL9000]

Editor you should watch 'moon machines'. Hunt around on you tube and you might find the program. Superb documentry which looked at the engineering behind the Apollo program

http://en.wikipedia.org/wiki/Moon_Machines

'the space suit' episode. It briefly shows you the video of that vacuum incident. The program mainly focuses on the engineering problems, early designs of space suits

*Fall on your back, and you couldn't right yourself.
*Cooling problems, early suits would get far too hot.
*Fire. After the apollo fire they had to re-engineer the suit to make it more fire proof.

As for survival time in vacuum, NASA tried experiments with monkeys. 3 minutes is the limit due to brain damage. (normal first aid advice is that resuscitation has to start within 3 minutes otherwise casualty will suffer brain damage)

 

[Dillinger4]

I am not going to try it, I don't like sunburn.

 

[editor]

But - in theory - you could have a very quick jog on the surface of Mars around the equatorial regions in nothing but your undies and survive.

 

[EastEnder]

I am not going to try it, I don't like sunburn.

Interestingly enough, sun burn is probably the 2nd most worrisome concern about finding yourself floating, unprotected in the vacuum of space (1st being the irksome lack of oxygen). In the absence of a conductive medium (like air or water), the human body cools very slowly indeed - you're in no danger of dying from hypothermia. However, deprived of the filtering quality of the atmosphere, the unimpeded glare of the sun will give you the mother of all sun burns in only a few minutes. Obviously it does depend on which bit of space you find yourself marooned in. In low earth orbit you've got to deal with suffocation & sub burn (and avoid being hit by the ISS), but if you're kicked out of the spaceship a few thousand miles above earth, you might find yourself floating about in the Van Allen belts. Then it'd be a toss up between sun burn & radiation as to which fried your oxygen deprived corpse first.

 

[8ball]

I'd give it a go for 30 seconds in the name of science. I want some SPF 30, though.

 

[EastEnder]

But - in theory - you could have a very quick jog on the surface of Mars around the equatorial regions in nothing but your undies and survive.

Atmospheric pressure at the surface of Mars is roughly equivalent to an altitude of 100,000 feet above Earth. You might be able to jog a few metres before the residual oxygen in your blood is used up. You'd actually suffer more from cold on Mars than you would in space. There's an atmosphere, albeit it very tenuous, and your feet would be touching the ground - lots of areas to conduct heat through.

 

[fogbat]

Who made you King of Space?

 

[stuff_it]

Who made you King of Space?

It's good to have ambitions...

 

[IMR]

So you'd be alright for doing a short space walk just with a little oxygen bottle and some sun lotion?

 

[ATOMIC SUPLEX]

But isn't all the brain damage due to lack of oxygen? How long could you survive with just an divers oxygen tank?

 

[spacemonkey]

I want to be executed for mutiny by being ejected from a spaceship cargo bay. I would defiantly scream I REGRET NOTHING, before my cries are deafened by the vacuum of space.

(then with my dying seconds I would pretend to swim away from the ship)

 

[weltweit]

Their swim bladders have a tendency to go pop....

A volume of liquid encased in a flexible membrane (which is essentially what we are) does not react dramatically to pressure changes. Liquids are essentially incompressible (apart from at very extreme pressures), which is why hydraulic systems work - you wouldn't want a compressible liquid in your car's brake lines. So it therefore follows, that if the liquid in a given volume at one atmosphere has not been compressed, why would it expand when the pressure drops to nothing? No expansion, no change in size, equals no explosion.

Gasses, on the other hand, are much more entertaining when subjected to big changes in pressure. If you do unexpectedly find yourself in a hard vacuum, don't hold your breath, don't try to keep farts in (this is no time for manners) and pray you've got decent fillings - if the dentist trapped any air bubbles under the amalgam, they're about to get a whole lot bigger...

indeed you make a good point.

 

[EastEnder]

But isn't all the brain damage due to lack of oxygen? How long could you survive with just an divers oxygen tank?

I think you might find it a bit difficult to breath pressurised oxygen in a vacuum... In the absence of normal air pressure, air from an aqualung would expand massively - the regulator would be ripped from your mouth, hopefully before your lungs burst.

 

[ATOMIC SUPLEX]

I think you might find it a bit difficult to breath pressurised oxygen in a vacuum... In the absence of normal air pressure, air from an aqualung would expand massively - the regulator would be ripped from your mouth, hopefully before your lungs burst.

So what do spacemen use? I'll have one of them.

 

[EastEnder]

Pressurised spacesuits!

 

[Melinda]

I want to be executed for mutiny by being ejected from a spaceship cargo bay. I would defiantly scream I REGRET NOTHING, before my cries are deafened by the vacuum of space.

(then with my dying seconds I would pretend to swim away from the ship)

Now that's a death I could respect. Your crew would always know deep down that you'd been punished too harshly because in the end, you did have their interests and indeed the survival of the species in mind when you did what you did.

But it would be even better if it turned out your consciousness were then magically downloaded into a spare body housed in a resurrection ship.

Now THAT's a fecking twist, Ron Moore.

 

[editor]

So am I down to a 10 second jog in my undies on Mars?

 

[Gromit]

David Blaine could live unprotected in space for at least a month. Fact.

 

[editor]

David Blaine could live unprotected in space for at least a month. Fact.

Without eating.

 

[stuff_it]

Shall we start a fund to send him to find out?

 

[EastEnder]

So am I down to a 10 second jog in my undies on Mars?

I had always imagined that man's first foray on the red planet would be rather more august... at the very least, I hope you've prepared something suitably historic to say!

"One small step for man, one short jog for an inappropriately attired Welshman..."

 

[19sixtysix]

I always thought that humans exploded in a dramatic fashion.

Hollywood science strike again

 

[19sixtysix]

So am I down to a 10 second jog in my undies on Mars?

I'd maybe wear some tight fitting water proof ones cause unless your sphincter is good the vacuum will be causing some leakage as well.