Death in space

[Bruce]

I'm sure there are links to sites that give a more expert opinion, but the Don't Hit Me thread put me in in a mood to theorize, so I'm going to give it my best shot and let you guys do the digging and criticizing.

I remember a scene fromt he movie Event Horizon where a man is suddenly exposed to space. His veins swell, his eyes bleed, and he coughs blood. In the movie Mission to Mars, a man becomes an instant popsicle. I also remember movies where people's eyes bulge and explode. Lies, all lies, I say.

First of all, the sudden drop in pressure would cause gases to expand. Dissolved gasses in your blood would expand and collect in your joints, causing "the bends", but this would take a minute or two. The air in your lungs would expand, but it would exit through your mouth and that would be that. Water does not expand in a vacuum, thus no part of you would swell, explode, or rupture.

Heat cannot travel through a vaccuum, so you wouldn't freeze instantly. A vaccuum is a near perfect insulator. Your thermos works because it contains a vacuum. You would slowly freeze in space because the water in your body would slowly evaporate due to the low pressure, and the evaporating water molecules would carry away the heat.

So how would you die if you were suddenly exposed to space? Let's assume you are sufficiently far away from a star and not exposed to significant solar wind. You wouldn't freeze instantly, so you would most likely die from suffocation due to the lack of oxygen. It would take about a minute or two for you to pass out as you gasp for air. You would feel very cold as the water on your skin quickly evaporates and you loose water and heat with every gasp. Not such a bad way to die, compared to fire or stabbing.

After you pass out and die, the remaining water in your body would diffuse slowly through your pores and orifaces, taking your remaining heat with it. Thus you would effectively be freeze-dried. Bacteria remaining in your body would likely go to work on decomposing you for a day or two, but not even bacteria can do anything without water. Your body would be perfectly preserved (though considerably shrunken) until you drift near a sun or planet.

Do you suppose this may be a popular thing for rich folk some day? To have your body launched into space so that it might one day be found by intelligent life and perhaps cloned? Sounds pretty cool to me.

Well, I'm off to enjoy the rest of my Saturday evening. Feel free to criticize or post links to other opinions. There might even be some research that was done on mice or something.

[rppa]

I remember a scene fromt he movie Event Horizon where a man is suddenly exposed to space. His veins swell, his eyes bleed, and he coughs blood. In the movie Mission to Mars, a man becomes an instant popsicle. I also remember movies where people's eyes bulge and explode. Lies, all lies, I say.

Some sci-fi authors have addressed this. In more recent sci-fi, characters survive exposure to vacuum for periods close to a minute. I think I remember one story where the characters have to go from one ship to another without the benefit of suits. Sorry, can't remember details but I suspect that both Arthur C. Clarke and Larry Niven have dealt with this.

I seem to remember that NASA has a definitive article on their site somewhere. Let's see... ah yes, here we go

http://imagine.gsfc.nasa.gov/docs/as...rs/970603.html

Heat cannot travel through a vaccuum, so you wouldn't freeze instantly. A vaccuum is a near perfect insulator. Your thermos works because it contains a vacuum.

Actually, that's not completely true. The sun does a very nice job of getting heat to us through a vacuum (the infrared part of its spectrum). Heat won't travel through vacuum by conduction, but it will travel by radiation. So if you aren't exposed to a source of energy, you will radiate as a blackbody, eventually becoming quite cold indeed. The surface of the moon can get down to around -150 C when out of the sun.

A thermos bottle is designed to minimize both conduction and radiation. Shiny surfaces help keep radiation in.

http://home.howstuffworks.com/thermos2.htm

[Zombified]

Quote:

Originally posted by Bruce
I remember a scene fromt he movie Event Horizon where a man is suddenly exposed to space.

I sincerely hope you are never exposed to vacuum, Bruce, because you will die thinking of this crappy, crappy movie.

[69dodge]

Quote:

Originally posted by Bruce
Dissolved gasses in your blood would expand and collect in your joints, causing "the bends", but this would take a minute or two. [...] Water does not expand in a vacuum, thus no part of you would swell, explode, or rupture.

What about the dissolved water vapor in your blood?

Water at body temperature boils at around 1/20 of atmospheric pressure.

[epepke]

Quote:

Originally posted by Bruce
I'm sure there are links to sites that give a more expert opinion, but the Don't Hit Me thread put me in in a mood to theorize, so I'm going to give it my best shot and let you guys do the digging and criticizing.

The US Air Force did tests on this out the wazoo.

Basically, if you as a human are exposed to sudden explosive decompression, you have about thirty seconds of consciousness. There are no bends, really: the nitrogen concentration isn't high enough. There may be some serious pain in your sinuses, though. After a while, there is some swelling and some bursting of capillaries near the skin, but you don't care, because you've already suffocated. No eyeballs popping out, etc.

It's only a 14 PSI difference, after all. Furthermore, if you're in a spacecraft, you may be breathing pure oxygen at 3-4 PSI and doing just fine anyway.

One of the designs that has been tested for a space suit is basically just a body-sized support stocking, a mesh that compresses the skin but has holes in it. Maybe you put mylar or something around it to reflect the sun, because you probably don't want all that hard UV. It actually works pretty well. This close to the sun, if you're in the sun, heat is a bigger problem than cold, but sweat glands do evaporative cooling just fine in space.

[Always Free]

"After you pass out and die, the remaining water in your body would diffuse slowly through your pores and orifaces, taking your remaining heat with it. Thus you would effectively be freeze-dried. Bacteria remaining in your body would likely go to work on decomposing you for a day or two, but not even bacteria can do anything without water. Your body would be perfectly preserved (though considerably shrunken) until you drift near a sun or planet."

What would the body feel like? Would it be hard to the touch like a frozen piece of meat? Or something else?

[Zep]

This was an integral part of the story in Kubrik's 2001: A Space Odyssey. Character survived, story-line continued.

Carry on!

[Bruce]

Cool stuff! Thanks!

Does infrared radiation fall under the definition of "heat" in classical physics? I thought infrared was considered light until it struck a material object. Maybe that has changed now, or maybe I didn't understand it at the time. I have trouble with the concept of heat because I tend to think in terms of physical objects. To me, "heat" means vibrating molecules, and "light" is a particle of some sort. Yes, I know light is supposed to be a considered a wave, but I can't seem to grasp the concept of a wave traveling through a vaccuum.

[Bruce]

Quote:

Originally posted by Zombified
I sincerely hope you are never exposed to vacuum, Bruce, because you will die thinking of this crappy, crappy movie.

No kidding! That movie was awful. The best actor spent 98% of the movie in a coma. The most realistic part of the movie is when the one guy goes rushing into the ship to see if he can disarm the bomb and sees that there's only 4 seconds left. No screaming, no trying to run away, he just squints and let's out a defeated whimper.

[MRC_Hans]

Somebody did a SF short story on "vacuum breathing", probably ACC, it would be like him. The thing is that most effects of a short exposure to vacuum are transitory. You might get a version of the bends, but once you are back in pressure, that is over. You might burst eardrums and capillaries, but you'll survive that. Asphyxiation (sp?) is the problem.

The short story I read contained an experiment, that you all can do:

Breathe well through for a while, then fill your lungs and hold your breath, timing it. Most people can do 1-2 mins, then the need for fresh air becomes unbearable.

After your breathing is back to normal, try this: Breathe heavily for a minute or so (if you begin to feel dizzy, procede to next step).

Now EMPTY your lungs, hold your breath (not inhaling) and time it.

The result will most likely surprise you.


The reason you can hold your breath longer with empty lungs is that the urge to breathe is not governed by lack of oxygen, it is governed by excess of carbondioxide. This is the reason that certain gas atmospheres are such insidious killers: If you breathe pure nitrogen, there is no CO2, and you will just pass out, never noticing a thing.

So, according that SF story, if you saturate your blood with oxygen (that is what deep-diving whales do), you should be able to survive in vacuum for several minutes, with no long-term consequences.

Hans

[Ziggurat]

Quote:

Originally posted by Bruce
Cool stuff! Thanks!

Does infrared radiation fall under the definition of "heat" in classical physics? I thought infrared was considered light until it struck a material object. Maybe that has changed now, or maybe I didn't understand it at the time. I have trouble with the concept of heat because I tend to think in terms of physical objects. To me, "heat" means vibrating molecules, and "light" is a particle of some sort. Yes, I know light is supposed to be a considered a wave, but I can't seem to grasp the concept of a wave traveling through a vaccuum.

Infrared radiation is indeed light. And you can indeed think of heat as atoms vibrating. But here's the connection: when those atoms are vibrating, the electric charge they carry vibrates too. And accelerating charged particles give off radiation. Every object gives off radiation. The hotter the object, the more radiation is given off, and the higher the frequency of the light given off. In this sense, infrared radiation emitted by warm objects is exactly the same as the light given off by an incandecent light bulb (which has a very hot fillament). This light carries energy, and when that light (visible, infrared, or whatever) hits another object and is absorbed, the energy generally turns into heat (solar cells are an example where some of that energy is converted into something other than heat). The physics of heat is called thermodynamics, and the phenomena of objects giving off radiation based on how hot they are is often refered to as black body radiation, in case you're curious to do some further googling. As an historical note, the study of blackbody radiation played a crucial role in the early formulation of quantum mechanics. Classical thermodynamics predicted an infinite amount of radiation energy anywhere that was in thermal equilibrium, something that was clearly not true and was termed the ultraviolet catastrophy (since the extra, non-existent energy was at higher wavelengths). It took quantum mechanics to fix the problem in the theory, which it did quite nicely.

[Ziggurat]

Quote:

Originally posted by MRC_Hans
Somebody did a SF short story on "vacuum breathing", probably ACC, it would be like him. The thing is that most effects of a short exposure to vacuum are transitory. You might get a version of the bends, but once you are back in pressure, that is over. You might burst eardrums and capillaries, but you'll survive that. Asphyxiation (sp?) is the problem.

If you don't manage to hold your breath the whole time, I think you'll die even if reintroduced to air. If your lungs end up in vaccum, you'll probably burst capillaries all over the place (and there's a LOT of surface area for that to happen over). Bleeding from the eyes is survivable, bleeding from the lungs may not be. I'm not sure how much positive pressure you can maintain just by trying to hold your breath, but I don't think it's very much.

[exarch]

Quote:

Originally posted by 69dodge
What about the dissolved water vapor in your blood?

Water at body temperature boils at around 1/20 of atmospheric pressure.

So how would you get the water in your blood to 1/20 of atmospheric pressure?
Apparently, your skin and other tissues are remarkably resilient, and won't allow your internal pressure to drop that significantly. Definitely not to 5% of normal pressure.

Quote:

Originally posted by MRC_Hans
So, according that SF story, if you saturate your blood with oxygen (that is what deep-diving whales do), you should be able to survive in vacuum for several minutes, with no long-term consequences.

Actually, that is what freedivers do too. They hyperventilate and saturate their blood with oxygen, which also allows them to delay the urge to breathe (sometimes until it is too late).

[exarch]

Quote:

Originally posted by Ziggurat
If you don't manage to hold your breath the whole time, I think you'll die even if reintroduced to air. If your lungs end up in vaccum, you'll probably burst capillaries all over the place (and there's a LOT of surface area for that to happen over). Bleeding from the eyes is survivable, bleeding from the lungs may not be. I'm not sure how much positive pressure you can maintain just by trying to hold your breath, but I don't think it's very much.

NO! DO NOT HOLD YOUR BREATH!
That is one of the things the NASA article is very clear about.
If you try to hold your breath, you will damage your lungs. If you let the air out, there's apparently enough oxygen left in your blood to stay conscious anywhere between 30 seconds up to 2 minutes.

[The Central Scrutinizer]

And what would be the effects on an unladen swallow???

[exarch]

Quote:

Originally posted by The Central Scrutinizer
And what would be the effects on an unladen swallow???

An African or a European swallow?

[epepke]

Quote:

Originally posted by Bruce
Cool stuff! Thanks!

Does infrared radiation fall under the definition of "heat" in classical physics? I thought infrared was considered light until it struck a material object. Maybe that has changed now, or maybe I didn't understand it at the time. I have trouble with the concept of heat because I tend to think in terms of physical objects. To me, "heat" means vibrating molecules, and "light" is a particle of some sort. Yes, I know light is supposed to be a considered a wave, but I can't seem to grasp the concept of a wave traveling through a vaccuum.

No, you're right. Infrared radiation consists of particles. Of course, it's guided by a physics called QED which has mathematics that are kind of wavy.

We have phrases like "wavelength" and "particle/wave duality" which are holdovers from the old days when people didn't know what the hell they were talking about, but the words have stuck.

In any event, a black body can radiate at a lot of wavelengths, but the infrared ones represent the kind of temperatures we usually talk about.

[Capsid]

The ill-fated Soyuz 11 mission ended in the deaths of the 3 cosmonauts due to a valve that had been jolted open by accident as the spacecraft undocked, causing the the air to leak away into space. Death was by asphyxiation. No popping eyeballs.

[Soapy Sam]

Hans- It wasn't a short. In the novel "Earthlight", the crew of the damaged "Acheron" crossed to the rescuing vessel "Pegasus", on hand lines, without space suits. They had previously hyperventilated in a high partial pressure 02 atmosphere to "saturate" the blood and tissues with oxygen, after which they exhaled to avoid ruptured lungs. Sunburn was quoted as the main hazard.

Of course this is fiction, and from 1963 at that.

As has been pointed out, Clarke recycled the trick when Dave Bowman outflanked HAL in 2001.

[rppa]

[quote]Originally posted by Bruce
Cool stuff! Thanks!

Does infrared radiation fall under the definition of "heat" in classical physics? I thought infrared was considered light until it struck a material object.

I'm going to disagree with another poster and say that this characterization isn't quite true. But the real truth is that "light" is a fuzzy characterization in physics. Visible light and IR, shorter wavelengths like UV and gamma and longer wavelengths like radio and microwaves are all special cases of electromagnetic radiation, governed by the same rules. Nobody says "this is light, this one isn't".

So IR radiation falls under the definition of radiation. Like all radiation, it is a form of energy transfer. The energy is carried in discrete bundles called photons, and the energy of a photon goes as 1/wavelength.

Maybe that has changed now, or maybe I didn't understand it at the time. I have trouble with the concept of heat because I tend to think in terms of physical objects. To me, "heat" means vibrating molecules, and "light" is a particle of some sort.

Temperature means vibrating molecules. "Heat" refers to the energy. Even in classical thermodynamics, "heat" is a difficult concept to pin down, but I think it's fair to say that it describes energy transferred between objects.

My all-time favorite online physics source is Hyperphysics. Here's what they say about heat: http://hyperphysics.phy-astr.gsu.edu...o/heat.html#c1
"Heat may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy."

Hot objects in vacuum get colder, and they do so by emitting blackbody radiation. Thus, the radiation is the mechanism for the heat transfer to distant objects. As a matter of fact only part of this spectrum is in the infrared, but for objects not hot enough to glow, that's by far the biggest part of the spectrum.

Think about the fact that infrared photography is used to distinguish the temperature of objects from a distance.

Yes, I know light is supposed to be a considered a wave, but I can't seem to grasp the concept of a wave traveling through a vaccuum.

It bothered 19th century physicists a lot, too. They postulated the existence of an "ether" as the medium in which the waves travel. Unfortunately attempts to figure out whether we were moving or at rest with respect to the medium (the Michelson-Morley experiment) led to the conclusion that the ether, if it exists, is at rest for all observers. The simpler conclusion is that there is no ether.

The wave description of radiation works very well, and these travelling EM fields go nicely through vacuum. If it makes you happier to think in terms of the QM description of photons, so be it. "EM radiation" is really the aggregate behavior of many photons.

[Lothian]

Quote:

Originally posted by Bruce
I also remember movies where people's eyes bulge and explode.

Total recall, I recall.

[Michael Redman]

Outland, if I remember right, with Sean Connery. People more or less exploded.

I don't really understand why the water wouldn't start to boil. I can't believe there wouldn't be room for expansion of the blood to the point that some of the water vapor became gas, and then I would think it would be all over.

[Bruce]

Quote:

Originally posted by Michael Redman
Outland, if I remember right, with Sean Connery. People more or less exploded.

I don't really understand why the water wouldn't start to boil. I can't believe there wouldn't be room for expansion of the blood to the point that some of the water vapor became gas, and then I would think it would be all over.

Because your circulatory system is remarkably good at maintaining pressure and repairing leaks. This is why you have this magical property called "blood pressure" and you don't bleed to death when you get a cut. If your blood pressure is maintained, your blood will not boil.

[Michael Redman]

A blood pressure of 120/80 mmHg is equivilent to 2.32/1.55 psi above ambient pressure. I wouldn't think that the vessels' ability to withstand normal blood pressure has any bearing on whether they can withstand boilding blood after a 14 psi drop in ambient pressure.

[epepke]

Quote:

Originally posted by Michael Redman
A blood pressure of 120/80 mmHg is equivilent to 2.32/1.55 psi above ambient pressure. I wouldn't think that the vessels' ability to withstand normal blood pressure has any bearing on whether they can withstand boilding blood after a 14 psi drop in ambient pressure.

This is getting tiresome.

1) It isn't a 14 PSI drop in pressure. If you're in a spacecraft, you're probably breathing pure oxygen at 3 to 4 PSI.

2) The Air Force put actual people into actual vacuums. Their blood didn't boil; their lungs didn't explode; their eyeballs didn't pop out. They even exposed them to explosive decompression, and those things didn't happen in those cases, either. Just which part of this is so terribly difficult to understand? It's been tried. It doesn't happen. We call this "reality." Whether you like it or not.

[69dodge]

I was just speculating about the boiling blood. I mean, I looked up the correct vapor pressure, but other than that, I don't really know anything about it. If it was actually tried, then of course whatever happened is what happens.

[The Central Scrutinizer]

Quote:

Originally posted by exarch
An African or a European swallow?

I don't know. Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhh...............

[neutrino_cannon]

In physics recently we were treated to the spectacle of a glass of water in a vacuum chamber. It wasn't the best vacuum ever, but I think the pressure got pretty low (not pressure gauge). The water did not boil, I noticed, but the dissolved oxygen and other gasses in the water did nucleate as bubbles along the sides of the glass. We never tested, but I'm pretty sure that just a little heat would have boiled the water easily. There was quite a bit of condensation on the inside of the vacuum chamber, so I imagine that if you were under a lot of solar radiation and in a vacuum, you might be in trouble.

I decided I could probably survive at least a little while in a vacuum, but that I probably wouldn't want to. I'm also fairly sure that I won't have to deal with this contingency in the near future. I suppose I'd have bigger things to worry about then.

I wonder if birds, thanks to their siginificantly different lung design would do better/worse in a vacuum.

[Bruce]

Quote:

Originally posted by neutrino_cannon
In physics recently we were treated to the spectacle of a glass of water in a vacuum chamber. It wasn't the best vacuum ever, but I think the pressure got pretty low (not pressure gauge). The water did not boil, I noticed, but the dissolved oxygen and other gasses in the water did nucleate as bubbles along the sides of the glass.

In regards to blood, don't forget the property of boiling point elevation. Blood has other 'stuff' dissolved in it, therefore, it's boiling point will be higher than that of water.

[Capsid]

Quote:

Blood has other 'stuff' dissolved in it, therefore, it's boiling point will be higher than that of water.

Don't you mean lower than water?

[Michael Redman]

Quote:

Originally posted by epepke
2) The Air Force put actual people into actual vacuums. Their blood didn't boil; their lungs didn't explode; their eyeballs didn't pop out. They even exposed them to explosive decompression, and those things didn't happen in those cases, either. Just which part of this is so terribly difficult to understand? It's been tried. It doesn't happen. We call this "reality." Whether you like it or not.

I was not aware of that. I missed your previous post. Can you provide a link discussing air force tests on humans? I think that would be quite interesting.

Please forgive my ignorance, and the horrible offense it appears to have caused you.

[Soapy Sam]

I believe NASA stopped using pure oxygen atmospheres afterr the Apollo 1 fire.

[Rob Lister]

Quote:

Originally posted by Michael Redman
I was not aware of that. I missed your previous post. Can you provide a link discussing air force tests on humans? I think that would be quite interesting.

Please forgive my ignorance, and the horrible offense it appears to have caused you.

This has me curious too. Reading the referenced post, as posted, makes me think those Air Force guys are real bastards!

Plus, (please don't call me names for asking this) wouldn't such exposure cause, at the very least, a body-wide hickey?

If not, why not?

[Mason]

A few links with good info and further links to more sources...

http://imagine.gsfc.nasa.gov/docs/as...rs/970603.html

http://www.sff.net/people/geoffrey.landis/vacuum.html

Didn't see any new info about NASA or anyone else actually conducting intentional human experiments, but there have been a few accidental exposures that give us good data to expand upon.

[Bruce]

Quote:

Originally posted by Capsid
Don't you mean lower than water?

Of course not. The more stuff that's dissolved in water, the higher the boiling point. That's how anti-freeze works. It helps keep the water in your radiator from boiling.

Boiling Point Elevation

[Capsid]

Quote:

The more stuff that's dissolved in water, the higher the boiling point

OK thanks, so where did I get this idea that adding salt to water would make it boil faster? Old wive's tale?

[Bruce]

Quote:

Originally posted by Capsid
OK thanks, so where did I get this idea that adding salt to water would make it boil faster? Old wive's tale?

Most people think that adding salt to water makes it boil faster. It actually raises the boiling point, thereby, making the food cook at a higher temperature, thereby cooking it faster. I think that's the logic, anway. My wife explained it to me once. I'll bet that Alton Brown has already given a better explaination for it on one of his episodes.

edited to add:

Ah, here we are: http://www.saltinstitute.org/29.html

"Salt added to water makes the water boil at a higher temperature, thus reducing cooking time. (It does not make the water boil faster.)"