What happens to an unprotected human body in space?

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

by spoon16 • 16 years ago

195 41 16 years ago

imagine.gsfc.nasa.gov

jarin• 16 years ago

Sounds like your lacrimal fluid would boil off, but maybe if you keep blinking you might be able to operate the airlock handle when jumping between airlocks?

whatwhatwhat2• 16 years ago

This article just leaves me wanting to ask more questions...

_delirium• 16 years ago

Same here, and oddly I seem unable to turn up a good book passage or scientific paper on the subject (maybe it's just that my Google Books and Scholar keywords are bad?). Surely someone, somewhere, must've written a review article with a title like, "The Effects of a Vacuum on the Human Body", providing a nice survey of the known facts?

The closest I can find is a 1974 paper reviewing the effects of local pressure reductions, e.g. placing someone's arm in a low-pressure chamber, or applying high suction to a wound. Unfortunately, doesn't seem to be available online, but here's the first page: http://physrev.physiology.org/cgi/pdf_extract/54/3/566

whatwhatwhat2• 16 years ago

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

neonak• 16 years ago

Why the boiling?

spectre• 16 years ago

As pressure decreases boiling point also decreases, so in a vacuum it is below your body temperature.

http://en.wikipedia.org/wiki/Atmospheric_pressure#Boiling_po...

fowlerrr• 16 years ago

If I can remember my high school physics, basically it's because of the low pressure.

Pressure x Volume = Temperature, so as the pressure decreases, so does the temperature.

But Wikipedia answers it better than I can: http://en.wikipedia.org/wiki/Boiling_point

jjs2• 16 years ago

You're looking for the Ideal Gas Law (http://en.wikipedia.org/wiki/Ideal_gas_law), which is derived from Boyle's Law (relation between gas pressure and volume), and Charles's Law (expansion of gas when heated).

The related concept here is that liquids remain liquid when the vapor pressure of the substance is less than the atmospheric pressure.

So, by the above laws, you can make water boil by (a) heating the water to increase the vapor pressure, or (b) reducing the atmospheric pressure to less than the existing vapor pressure of the water, or (c) some combination of (a) and (b).

mmaunder2• 16 years ago

Get a syringe. Fill it about a quarter way with water. Turn it facing up and squirt out any air bubbles. Block the end where the needle goes with your finger. Pull the plunger back hard as if you're filling it all the way up. You'll pull a hard vacuum and you'll see the water inside bubble as it boils at room temp.

ovi256• 16 years ago

Used to do that each time I had a syringe available. Such fun.

by• 16 years ago

In a gas the molecules are moving around with lots of space between them without much interaction. Some quickly, some slowly, all in different directions. Occasionally they collide and bounce off each other, or more rarely they may temporarily form weak (liquid) bonds with each other until a fast molecule hits them and breaks them apart.

In a liquid the molecules (which are indistinguishable from gas molecules of course if you looked at them individually) are moving much slower and form and re-form weak (liquid) bonds with the molecules near them. But still there are some moving faster and others more slowly and they are going in random directions.

Now think about the surface where the liquid meets the gas. There are some gas molecules that plunge into the liquid and become part of the liquid and there are some liquid molecules moving fast enough to escape from the liquid, breaking all their weak (liquid) bonds, and become part of the gas. The liquid surface at a molecular scale will not be a nice flat surface. It will be a complex seething bubbling thing with droplets and molecules leaving and rejoining the liquid. If we heat the liquid, make the molecules move faster, more of them will be moving fast enough to escape from the liquid. Anyway, if there are more molecules going from the gas to the liquid we say the gas is condensing, and if there are more going the other way the liquid is evaporating. Now think what would happen if we take away all the gas molecules - put the liquid into a vacuum. There will no molecules returning to the liquid, only liquid molecules becoming gas. Conversely, if we compressed the gas above the liquid we would get more gas molecules going into the liquid.

I think that's how it works.

knieveltech• 16 years ago

Straight out of Feynman's lectures. Well said.

elblanco• 16 years ago

It's due to the low pressure. Like with these guys. http://www.acenovelty.com/donace/coffeepen06.jpg

Myrth• 16 years ago

"and animal experiments confirm"

bastards...

ascuttlefish• 16 years ago

It does seem a bit cruel, to be honest.

ars• 16 years ago

Not if you anesthetize the animals first.

petercooper• 16 years ago

http://www.astronomycast.com/space-flight/ep-121-spacesuits/

Just because it's entertaining, the presenters are awesome, and you get to learn a lot of cool stuff (and they cite the link in question, too).

mmaunder2• 16 years ago

"...his last conscious memory was of the water on his tongue beginning to boil."

Reality is so much cooler than fiction. I've read just about everything Clarke, Heinlein and Asimov have written among many other physics sci-fi authors and none of them thought of that one.

timf• 16 years ago

Apparently this happened at Johnson Space Center in a vacuum, so the temperature would be high enough to make that happen with the reduced atmospheric pressure (see the chart at [1]). The temperature in space is far, far colder, I don't see how this could happen.

[1] http://www.iapws.org/faq1/boil.htm

EDIT: According to the replies at [2], the retained heat of ejected astronaut urine is enough to first cause boiling but that heat runs out quickly and you get ice crystals.

[2] http://www.newton.dep.anl.gov/askasci/gen01/gen01060.htm

Avshalom• 16 years ago

Well as far as spit on the tongue goes, any water that doesn't boil off remains in contact with the tongue/cheeks, conduction being way faster that radiation at 37c any spit that did freeze due to evaporative cooling would thaw out again very quickly.

It's different for urine which lacks the continual heat source. If you had a mouthful of water, instead of a thin sheet of spit, you'd likely end up with an ice cube for a while.

bjelkeman-again2• 16 years ago

"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."

Why was that? Does the low pressure force oxygen out of the blood in the lungs and thereby having oxygen "free" blood arriving in the brain? If you hold your breath you can easily hold it for a minute without loosing consciousness. So the low pressure must be actively taking oxygen out of the blood, otherwise I can't see that you would loose consciousness in 15 seconds.

How long did it take for Dave Bowman to exit the pod and pressurize the airlock? :)

jjs2• 16 years ago

How long did it take for Dave Bowman to exit the pod and pressurize the airlock? :)

(SPOILER if you haven't seen 2001: A Space Odyssey)

http://www.youtube.com/watch?v=e92vSua8XJY

In this clip, he ejects at about 0:20 and hits the lever around 0:27. You can see him go limp just after 0:34, before the chamber has finished pressurizing. 14 seconds.

So regardless of why the real-life (1965) test subject blacked out after 14 seconds, it appears that the makers of the (1968) film had done their homework!

brazzy2• 16 years ago

If you hold your breath, your lungs are still filled with air, which contains oxygen. So there's still some oxygen being transferred into your blood, it just gets less and less.

But actually, I suspect that the far more important factor is CO2, which leaves the blood in the lungs when there is air present.

berntb• 16 years ago

>>If you hold your breath, your lungs are still filled with air

Just let me note -- don't hold your breath when there are pressure differences between your lungs and the surroundings!!

You can find that in any scuba diving manual.

(Edit: I do realize the parent poster probably knows this.)

ugh• 16 years ago

You are absorbing only 25 percent of the oxygen, which suggests to me that having air still in you lungs can be very helpful in keeping you conscious. Is that right?

tjmc• 16 years ago

There have been a couple of cases where crews on business jets were very quickly incapacitated after a loss of cabin pressure most famously the aircraft of golfer Paine Stewart. Unfortunately, unconsciousness does seem to occur pretty fast. Supplemental O2 wasn't used in that case, despite it likely being close to hand.

jrockway2• 16 years ago

Also commercial jets: http://en.wikipedia.org/wiki/Helios_Airways_Flight_522

(It's a little embarrassing to count how many people have died because pilots have intentionally turned off power to warning systems that were warning of them of an actual problem. Here's another one: http://en.wikipedia.org/wiki/Northwest_Airlines_Flight_255. Same digits -- freaky.)

electromagnetic2• 16 years ago

Crew on flights typically get a better chance due to the higher pressure and the presence of O2, despite the low pressure. However, typically euphoria kicks in anyway and, according to some of what I've read, can potentially be worse than a complete absence of O2.

RyanMcGreal• 16 years ago

A bigger worry is the improbability of having another ship arrive to pick you up within 30 seconds.

dhs• 16 years ago

Don't panic, and a ship powered by an infinite improbability drive will pop up. Happens all the time...

jrockway2• 16 years ago

So that's what that tunnel of light is...

pclark• 16 years ago

Just like in Event Horizon (really)

coderdude• 16 years ago

In Event Horizon your eyeballs bleed. You start going into convulsions as your veins swell and everything is getting sucked out of you. That article made it sound kind of peaceful, provided you blew the air out of your lungs. Which, now that I think about it, is probably what you are referring to (exhaling all the air from your lungs).

sown• 16 years ago

Going from 1 ATM to 0 doesn't kill you but going from 9 ATM to 1 will

http://en.wikipedia.org/wiki/Byford_Dolphin#Diving_bell_acci...

johnohara• 16 years ago

My guess is the parachute record still stands. 19.5 miles is not quite 10% the minimum altitude of the space shuttle.

Then you jump and wait for the feeling to come back in your right arm.

metamemetics• 16 years ago

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

>On March 18, 1965, became the first human to conduct a space walk.

>At the end of the spacewalk, Leonov's spacesuit had inflated in the vacuum of space to the point where he could not re-enter the airlock. He opened a valve to allow some of the suit's pressure to bleed off, and was barely able to get back inside the capsule.

What happens to an unprotected human body in space?

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