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Survival in Space Unprotected is Possible

scientificamerican.com

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Re: Survival in Space Unprotected is Possible

#21

Post by danellis »

silvio wrote: post #8
error54 wrote: post #7

What the article fails to mention is that space is cold. Really, really cold averaging -454.81 Fahrenheit[1] making concerns about oxygen or water pressure irrelevant. The article should have been called "Survival in Vacuum Unprotected Possible." 1 - http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980301b....

Space is for all practical purposes a vacuum, thus the only cooling effect would be by radiation, given that the body wouldn't be in contact with anything around it, as opposed to what happens on the ground where it is surrounded by air or water in the sea. In these conditions, the change in temperature takes a long time. As stated in the linked article: "If we put a thermometer in darkest space, with absolutely noth…

There's an awful scene in the film 'Mission to Mars' where Tim Robbins removes his helmet in space, and his head instantly freezes. No, no, no!

Re: Survival in Space Unprotected is Possible

#22

Post by kyllo »

As a dog lover, their descriptions of the animal subjects studies they did made me cringe.

>During their exposure, they were unconscious and paralyzed. Gas expelled from their bowels and stomachs caused simultaneous defecation, projectile vomiting and urination. They suffered massive seizures. Their tongues were often coated in ice and the dogs swelled to resemble "an inflated goatskin bag," the authors wrote.

Horrible. If this knowledge is going to actually directly save human lives, and there's no better way, well OK then, but this is just a terrible, horrible thing to do to a creature like a dog or a chimpanzee.

Re: Survival in Space Unprotected is Possible

#23

Post by gus_massa »

ams6110 wrote: post #9
error54 wrote: post #7

What the article fails to mention is that space is cold. Really, really cold averaging -454.81 Fahrenheit[1] making concerns about oxygen or water pressure irrelevant. The article should have been called "Survival in Vacuum Unprotected Possible." 1 - http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980301b....

How does vacuum (the absence of matter) have a temperature?

Even if there were no atoms, you must consider the electromagnetic field (or photons if you want to think that you have particles).

If you have a perfectly empty box (with total vacuum inside) and the walls have some temperature (for example 2.7K) then, after a while, inside the box will appear the electromagnetic field with the blackbody radiation of the walls temperature.

It's convenient to assign properties to the electromagnetic field, in this case the temperature. And the correct temperature of the electromagnetic field inside the box is the same as the temperature of the walls.

And the best thing is that the walls are not necessary! You can assign a temperature to the universe background radiation. If the distribution of frequencies of the electromagnetic field is equal to the blackbody radiation of a 2.7K blackbody, then you can think that the temperature of the electromagnetic field is also 2.7K.

More details: http://en.wikipedia.org/wiki/Photon_gas

Re: Survival in Space Unprotected is Possible

#24

Post by HCIdivision17 »

kyllo wrote: post #22

As a dog lover, their descriptions of the animal subjects studies they did made me cringe. >During their exposure, they were unconscious and paralyzed. Gas expelled from their bowels and stomachs caused simultaneous defecation, projectile vomiting and urination. They suffered massive seizures. Their tongues were often coated in ice and the dogs swelled to resemble "an inflated goatskin bag," the authors wrote. Horrib…

I think you can be reassured that the only better way is to place people in hard vacuum, which most would assume too risky. A bit of our knowledge was gathered the traditional industrial way (via reporting on people getting hurt), but it looks like the animal testing was likely timely and informed the risks at stake.

I wondered just how many dogs were involved, and I found the following link: http://triscience.com/Animals/Muscle/experimental-animal-dec... It notes the test group was 125, with tests done in groups of 6. My impression is that their experience wasn't a waste, and was a benchmark study for decades.

While trying to find the original study, I stumbled across another that goes into some further detail. http://cousin.pascal1.free.fr/AVMA%20etude%20decom.pdf I don't have the constitution to read much medical research, but the impression is that the experience is markedly short. Physiologically decompression is pretty awful, but the subject doesn't suffer consciously. Hopefully that's a bit reassuring that the animals did not experience any horror film-like agony before blacking out (though it would be uncomfortable, to be sure).

Re: Survival in Space Unprotected is Possible

#25

Post by HCIdivision17 »

error54 wrote: post #7

What the article fails to mention is that space is cold. Really, really cold averaging -454.81 Fahrenheit[1] making concerns about oxygen or water pressure irrelevant. The article should have been called "Survival in Vacuum Unprotected Possible." 1 - http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980301b....

I worked on vacuum systems. Space is not cold, nor hot, nor happy. It's sort of the wrong way of looking at it.

Vacuum isn't. It is a terrible conductor of heat. So bad, that after 15 minutes a very small battery powered pen camera started to red on the edges of the video: it was starting to heat up! The only way to cool off is via radiation, which takes quite a while. If you had a large array of very conductive, high surface area material, then you could get cold. But our skin isn't like that. Rather, it's wet and insulative. The membranes that are wet immediately suffer evaporative cooling, but once frozen will have to sublime to cool any more, which is slow. The skin is dead on the outside and has layers of insulation in the form of water and fat.

No, the research, testing, and industrial accident reports show that you die from oxygen deprivation. (And you can find vacuum labeled as an asphyxiate, since inhaling it is deadly...)

EDIT: I should note that the temperature of the vacuum really is very low. That's not disputable. But there just aren't enough atoms in a vacuum for it to feel cold. It's one of those times our intuition about units sort of sets us up for failure: temperature is an average kinetic energy of each particle, and normally there are enough particles to matter. In a vacuum there usually aren't. (I'm lying of course: high energy plasmas can definitely heat something up given a few hours.)

Re: Survival in Space Unprotected is Possible

#26

Post by HCIdivision17 »

error54 wrote: post #14
gmaslov wrote: post #13

Earlier quoted context omitted.

Indeed. A living human probably generates more heat from the normal bodily processes than can be radiated away in space. For this reason spacesuits are equipped with coolers, not (AFAIK) heaters.

Thanks guys! I didn't even think about there being nothing around to transfer heat away the body. I would have figured that the fact that water boils and then freezes in space would mean (humans being mostly water) that a person would expire rather quickly unprotected.

I came across a neat explanation of why we don't freeze immediately: our skin's pretty good at keeping the wet parts of us inside! When I had been curious about this a few years ago, this was the thing that convinced me of it. After all, in order for the water in us to freeze, the higher energy water molecules need to go somewhere, right? (Of course, it's possible very small gas bubbles will dissolve into your blood, and that will quickly expire a person, but as noted elsewhere in this thread the pressure drop from atmo to vacuum is less than that normally experienced by divers.)

Also, I have covered a vacuum flange with my hand. Heckuva hickie, but otherwise harmless. Smarts a bit with a dash of bruising, but the skin holds up remarkably well.

Re: Survival in Space Unprotected is Possible

#27

Post by RVijay007 »

scott_s wrote: post #11
tokenadult wrote: post #2

A famous scene in the 1968 film 2001: A Space Odyssey showed this. (The actor, Keir Dullea, almost was badly injured in the shot showing him entering the spaceship airlock without his helmet on, by the way.) But as the article points out, such survival is only "for at least a couple of minutes. Not that you would remain conscious long enough to rescue yourself, but if your predicament was accidental, there could be t…

Event Horizon from 1997 also had a scene where someone survived a short trip through space.

Also the movie Sunshine.

Re: Survival in Space Unprotected is Possible

#29

Post by Houshalter »

Wtf is with the only two animal experiments being on dogs and chimps? I am ok with animal research, but on dogs? Or chimps which are closer to humans than any other animal? This research isn't even necessary. Everyone already knew going into the vacuum of space was bad.

Re: Survival in Space Unprotected is Possible

#30

Post by daeken »

Houshalter wrote: post #29

Wtf is with the only two animal experiments being on dogs and chimps? I am ok with animal research, but on dogs? Or chimps which are closer to humans than any other animal? This research isn't even necessary. Everyone already knew going into the vacuum of space was bad.

> Everyone already knew going into the vacuum of space was bad.

That line of thinking leads to a complete lack of actual science. As the article points out: going into the vacuum of space is nowhere near as bad as is conventionally thought. That's an incredibly valuable finding, and it gives us the information we need to create effective safety and recovery mechanisms in space.

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