Surviving in Space Without a Spacesuit

Geoffrey writes "The recent movie Sunshine features a scene (echoing the famous scene in 2001: a Space Odyssey) in which two astronauts have to cross from one ship to another without spacesuits. But, can you survive in space without a spacesuit? Morgan Smith, writing in Slate, asks whether this is realistic, and concludes: "Yes, for a very short time.""

Comments

Re:next time

[Marxist Hacker 42]

I haven't RTFA'd yet- but IIRC, the "Asmovian" version of this required that for maximum survival, you had to hyperventalate (to maximize oxygen storage in the bloodstream), empty the lungs, and be in shadow since the sun puts out so much energy that without an atmosphere you risk a pretty bad sunburn.

low-pressure spaceship env.

[fred fleenblat]

The decompression effects may be reduced/delayed if the space station uses a 100% oxygen atmosphere at a low pressure, then the pressure delta between what your body is equalized to and the vacuum is reduced so the trauma is delayed a bit.

The ISS uses normal sea-level pressure, but I believe some of the spacecraft used for the moon shots used the low-pressure environment.

Re:low-pressure spaceship env.

[evanbd]

There's a bigger problem with that though -- if you lower the pressure of the atmosphere, but add more O2 to keep the partial pressure the same, you increase the fire hazard. Inert gases like nitrogen act as a buffer and reduce flammability. Fires in spacecraft are a big deal, which (I believe) is why ISS uses higher pressure.

The major problem with exposure to vacuum isn't the pressure anyway, it's the lack of air. Furthermore, you can't hold your breath, because your lungs aren't strong enough to hold in the air. Without any air in your lungs, you get about 10-15 seconds of consciousness.

15 seconds?

[vigmeister]

I just expelled all the air out of my lungs as best as I could and it was exactly 24 seconds before it was physically impossible to hold my breath... I felt a weird kind of giddiness -almost a mild 'hit'. Sort of like when you smoke a strong cigar and inhale.

Surely, astronauts ought to have better lung capacity than yours truly?

Cheers!

Re:Imagine drowning if you couldn't hold your brea

[Raul654]

After he came to, they asked the tech what the last thing he remembered was. He told them the last thing he remembered before blacking out was the saliva on his tongue boiling away (due to the extremely low pressure lowering the boiling point of the saliva)

A Serious case of YMMV

[wsanders]

A long time ago I took a pressure chamber ride at NASA to 27,000 ft. I lasted about 15 sec until uselessness (the crew master didn't let us go all the way to LOC), and 27,000 is not a particularly extreme altitude. Generally, 50,000 ft is considered the altitude at which the partial pressure of oxygen is no longer adequate to maintain consciousness. You can survive up to about 80,000 if you "pressure breathe", i.e have a rig that forces oxygen into your lungs at a lightly higher pressure than ambient, but not enough to bust your lungs.

And as TFA pointed out you will embolize if you hold your breath above that more or less 80,000 ft altitude.

So if the acronum YMMV ever applies, it's here.

Wow, and TFA is wrong, too !

[Ihlosi]

At most, an astronaut without a suit would last about 15 seconds before losing conciousness from lack of oxygen. (That's how long it would take the body to use up the oxygen left in the blood.)

First piece of BS. No, your body doesn't use up the oxygen left in the blood in 15 seconds. In a vacuum (or, more broadly speaking, in any condition where the partial pressure of oxygen is lower in the lungs than in the blood), the gas exchange in the lungs is reversed - your blood will actually become deoxygenated while passing through your lungs. After 15 seconds, your brain will get hit by a blood supply that is pretty much completely deoxygenated - it's lights out then.

And then the part about air embolism - the pressure difference from going from the inside of a spacecraft (which is most likely pressurized at less than one atmosphere) to a vacuum is much lower than the pressure difference experienced by a scuba diver surfacing from a depth of, say, just 12 meters. "Vacuum" might sound nasty, but it's the pressure difference that is the problem here.

Re:SG-1 had a similar scene

[profplump]

I'm with you on the exploding -- if you're caught in space you want to do everything possible to reduce your internal pressure.

But it's not that cold in space. There's not a lot of ambient heat, but there's not a lot of conduction or convection either -- you only lose heat as fast as you radiate. So on the timescale of "holding your breath" the temperature of space is not a significant factor. Likewise the radiation you'd absorb over 60 seconds is likely not a large factor, unless you're particularly close to the source (I don't recall the episode, so I can't comment on their depiction of distance from the star(s)).

Re:Imagine drowning if you couldn't hold your brea

[xenocide2]

Really, I'd say conciousness for 10-15 seconds, and risk of death approaching 100 percent at 2 minutes, based on the link. Remember, the 2-3 minutes guy was examined by autopsy.

Re:SG-1 had a similar scene

[AdamThor]

you only lose heat as fast as you radiate

No, you'd lose heat as any liquid on your skin boiled away, wouldn't you?

Also you'd pick up heat from the sun. You mention radiation, but not how much of it ends up as heat. Doesn't the space station actually require cooling to keep people alive? I don't know what the final balance works out as...

been there

[starshining]

I've done 4 spacewalks and during vacuum chamber training we open our suit purge valve, allowing the pressure in the suit to drop a bit (from nominal 4.3 psi) and I did feel the sensation of the saliva bubbling; it is similar to the sensation of soda pop on your tongue. I haven't seen the movies mentioned (other than 2001), but my guess about vacuum exposure is that you are more likely to be injured by the flying debris (including your own velocity as you impact a wall or whatever) associated with sudden decompression through a hatch than by a very short exposure to 0 psi. During one chamber run, I had a water line poppet valve stick open when I disconnected from the chamber wall. The water stream broke up into droplets that immediately froze, producing an impressive shower of ice particles. Over about 5 to 10 seconds, the icing point traveled up the water stream and formed a clump around the poppet valve, sealing the leak. Oh, by the way, I tried whistling while EVA and even the nominal suit pressure is too low to produce an audible sound.

Exploding from decompression

[rev063]

I think the guy exploded from the inside out from rapid decompression - but I think that could of been a little Hollywoodish. I used to think of the human body exploding due to decompression being pure Hollywood, too, until I read this:

Subsequent investigation by forensic pathologists determined that diver D4, being exposed to the highest pressure gradient, violently exploded due to the rapid and massive expansion of internal gases. All of his thoracic and abdominal organs, and even his thoracic spine were ejected, as were all of his limbs. Simultaneously, his remains were expelled with force through the narrow trunk opening left by the jammed chamber door, less than 60 centimeters (24 inches) in diameter. Fragments of his body were found scattered about the rig. One part was even found lying on the rig's derrick, 10 meters directly above the chambers.

Now, this was a 6atm almost instantaneous decompression. Jumping into space would be at most a 1atm differential, so nothing like this is likely to happen. Gruesomely cool, though.

Re:SG-1 had a similar scene

[rev063]

And if you want some insight into the effects of truly extreme pressure changes on the human body (next to which the vacuum of space is peanuts) I recommend reading about the Byford Dolphin diving bell accident. Not for the squeamish.