What will a human like if exposed to vacuum?

[Cesrate]

·How long would consciousness stay, if holding breath before exposed to vacuum?

-Is that possible to hold breath in vacuum? Are these muscles strong enough?

·Will the tympanic membrane break in such a condition(one side 100kPa and one side 0 pa)?

·Will tear all gone and left a very dry and secreta covered eyeball? And will exposed nasal cavity be the same?

·Will mucous membrane be damaged?

·Will subcutaneous capillary vessels expand and make skin turn red?

Edited June 24, 2013 by Cesrate

[Kerbface]

I imagine they'd start to like air pressure a lot more.

[K^2]

You shouldn't try to hold your breath for the same reason that you should never try to hold your breath while surfacing when SCUBA diving. (Actually, you are never supposed to hold your breath while SCUBA diving.) You are going to get lung damage due to pressure difference. Going from 1 bar to vacuum is equivalent to going from 10m (33') bellow to the surface.

So your lungs won't help you one way or another. That leaves you with whatever oxygen is in your blood. Typically, you are looking at 20 seconds to 1 minute before passing out. Maybe a few minutes on top of that before brain damage and subsequent death.

As far as damage to your tissues, there really shouldn't be any over such short period of time. The only one I'm a little worried about is lungs, as they are going to rapidly cool due to evaporation, and unlike skin, they aren't really meant to be exposed to low temperatures. But even there, it would take some time for significant damage.

So all in all, so long as you remember to exhale during depressurization, and you manage to get to an air lock before you pass out, you should be fine.

[Kilmeister]

From what I've read you will only be conscious for about 10-15 seconds. But as K^2 said, attempting to hold your breath would be very bad and result in fatal damage to your lungs almost instantly due to rapid decompression, but otherwise you'd be able to survive a short period in a vacuum without any significant permanent damage otherwise.

[Nibb31]

You would lose consciousness in a matter of seconds. After that, it doesn't really matter, because you'll be dead. Wikipedia says this:

Experiments with other animals have revealed an array of symptoms that could also apply to humans. The least severe of these is the freezing of bodily secretions due to evaporative cooling. But severe symptoms such as loss of oxygen in tissue (anoxia) and multiplicative increase of body volume occur within 10 seconds, followed by circulatory failure and flaccid paralysis in about 30 seconds.[1] The lungs also collapse (atelectasis) in this process, but will continue to release water vapour leading to cooling and ice formation in the respiratory tract.[1]

A rough estimate is that a human will have about 90 seconds to be recompressed, after which death may be unavoidable.[2][3] The low pressure outside the body causing rapid de-oxygenation of the blood (hypoxia) is the primary reason for unconsciousness within 14 seconds.

Note that the effects are pretty much the same when an aircraft decompresses at high altitude. There have been several aircraft and space accidents involving decompression, incapacitating the crew.

Edited June 24, 2013 by Nibb31

[K^2]

Ah, right. Blood is still going to be losing oxygen through lungs and skin. I didn't really think of that. Makes sense for the time before loss of consciousness to be that much smaller, then.

[PakledHostage]

Note that the effects are pretty much the same when an aircraft decompresses at high altitude. There have been several aircraft and space accidents involving decompression, incapacitating the crew.

Agreed. Time of useful consciousness is already surprisingly low at typical airliner cruising altitudes. Figure 16-1 on page 16-3 of this FAA reference gives some numbers. This, incidentally, is why they tell you to put your own mask on first before assisting others. You do yours while you can still think straight, and then help anyone beside you who needs it once the oxygen is flowing.

Another interesting factor is the partial pressure of oxygen. At sea level, partial pressure of oxygen is roughly 21 kPa because air is 21% oxygen. 100% oxygen at 21 kPa also has a partial pressure of 21 kPa. It isn't enough to just maintain an equivalent partial pressure, however. I've read in a book about high altitude physiology by Dr. Charles Houston that low pressures also affect the way in which haemoglobin behaves, the permeability of the alveoli walls to O2 and C02, among other things. Spacecraft are sometimes designed to use a low pressure, high oxygen percentage atmospheres to maximise oxygen partial pressure while minimising structural weight. This was a factor in the Apollo 1 fire.

Edited June 24, 2013 by PakledHostage
Added link to Dr. Charles Huston's wikipedia entry

[Flixxbeatz]

Check this out.

(Warning: TMI inbound)

[Paprika]

"The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems."

[catmando]

after having trained real astronauts on the effects of altitude on their bodies.. your cells would rupture from the inside out because there is less pressure in space(meaning your cells are over pressurized they pop like a balloon.. blood boils at 64,000' at higher altitudes your cells explode and then sublimate ( solidifies becoming a chunk of ice) so in the real world you explode and that turns into pieces of ice..

safety tip for the day...

NEVER travel anywhere without your kerbalnaut suit

[Randox]

(I'm paraphrasing an article which goes through this in a bit more detail, found here: http://www.damninteresting.com/outer-space-exposure/)

Compliments of accidents exposing humans to hard vacuums in the past, we have a practical understanding of most of the effects, and science has been able to piece together a pretty good idea of everything else.

First, as pointed out, if you want to survive you have to exhale to prevent your lungs from rupturing during explosive decompression. Your digestive system, being much more durable, should be able to cope. You'll also get a lot of swelling very quickly from the rapid evaporation of water in your muscles, causing bruising, but the skin should be able to hold.

The nitrogen in your blood will boil (the bends), and if you have line of sight to the sun, your skin is going to suffer major burns.

You have about 10 seconds of useful consciousness before asphyxiation starts to set it (without extra air in the lungs, your brian would rapidly consume enough oxygen to start having trouble. Anyone who has ever stood up really fast and gotten dizzy, perhaps with narrowing vision and a rushing sound already knows exactly what this would be like). It also doesn't help that the lungs are pressure driven, as in, they will work backwards in a vacuum and dump oxygen out of your blood to accelerate hypoxia even more. You expect unconsciousness to set in at perhaps 15 seconds.

The body would be able to survive for about 90 seconds, and with intervention during this time (being placed back in a pressurized environment and being administered oxygen), you can make a full recovery. At around 90 seconds, your blood pressure will be so low that the blood will start boiling, causing cardiac arrest. No one has been successfully resuscitated past this point.

Edited June 26, 2013 by Randox

[Fuzzy Dunlop]

It's worth noting that if you can maintain air presssure to the lungs, humans are suprisingly well adapted for space. Skin is extremely airtight and comes with its own thermal control system, it's also easily strong enough to stop you exploding. The only problem is that without air pressure fluid would pool in all the places where the skin folds and stretches to allow for movement - which would be very debilitating. But if you had were wearing a tightfitting elastic webbing, kind of like a fishnet bodystocking (which sounds horrifying now that I think about it) you should be OK.

[Cooly568]

Scishow did a

It's quite informative.

[Pursuedtank]

Scishow did a

It's quite informative.

As did

(skip to 8:30)

and

[nyrath]

It's worth noting that if you can maintain air presssure to the lungs, humans are suprisingly well adapted for space. Skin is extremely airtight and comes with its own thermal control system, it's also easily strong enough to stop you exploding. The only problem is that without air pressure fluid would pool in all the places where the skin folds and stretches to allow for movement - which would be very debilitating. But if you had were wearing a tightfitting elastic webbing, kind of like a fishnet bodystocking (which sounds horrifying now that I think about it) you should be OK.

Yes, some researchers are trying to exploit that to make innovative space suits, most notably Professor Dava J. Newman. The technical term is "mechanical counter-pressure suit" or "biosuit".

http://mvl.mit.edu/EVA/biosuit/index.html

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

http://www.projectrho.com/public_html/rocket/spacesuits.php#id--Design--Skin_Suits

[The Jedi Master]

Holding your breath, despite what the movies say, is a TERRIBLE idea, as already mentioned. The only way a human could survive in vacuum without protection is if they breathed deep before entering the vacuum, then breathed out and left his/her mouth open until rescue. Even then, you'd only last about three to five minutes. And that's not even accounting for the effect of the zero gravity, the extreme coldness of space, etc...

[Tiberion]

From NASA:

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

So the exploding and blood boiling, at least immediately, doesn't happen. Though having the moisture in your mouth start boiling within 15 seconds can't be a good thing.

[brooksy125]

You wouldn't be able to hold your breath anyway, the vacuum would simply drag it out of your lungs instantaneously.

[Tommygun]

This shows an actually decompression accident at a NASA test facility while testing a space suit in a vacuum chamber.

Note: The person did survive unharmed, so nothing gruesome in the video.