Submitted by OvidPerl t3_121eza5 in todayilearned
Imagine the terror of your helmet filling with water and all you want to do is take it off, but you’re in space so that would kill you as well.
I’d crack open a glove.
Still dead, naturally, but I’ma leave a pretty corpse.
It won't work, there is a protection for that. You can open it but then the suit will prevent air from leaking out there. Better lose your hand than the whole suit.
The only option was to drink it, but unless you absolutely know where the leak is from it can potentially kill you.
Chris Hadfield was told by Houston to vent his helmet when his eyes were blinded by contaminated tears on an EVA. I assume you could do something similar here.
Yeah all the comments acting like instant death would occur if any part of your body is exposed to vacuum are exaggerating a lot. It would certainly be unpleasant, possibly damaging to tissue, but the mortal danger of exposure to vacuum is way overexaggerated by popular media.
The actual danger of removing his helmet in the situation above is that it wouldn't solve the problem, because the water would just linger there with no outside force directly clearing it off from him. It'd be pushed in all directions due to venting gas from his suit presumably, but the water would be expanding at that point anyways. If he just slaps his helmet back on it would, presumably, still contain a large amount of water and continue filling with water.
The Hadfield vent might work though, since it creates a directional pressure differential. It actually did work to remove the ball of contaminated water from Chris’s eyes.
I assume it would depend on the amount of water. I feel like if it is enough water to fill a helmet to the point of threatening to drown, the expanding water itself would probably block up any small vent or opening in a helmet before a meaningful amount of it was evacuated. I'm not a space man though so it very well may work.
>The actual danger of removing his helmet in the situation above is that it wouldn't solve the problem
Without pressure, wouldn't the water immediately boil away? There literally wouldn't be anything holding the bonds together anymore.
Boil is doing a lot of heavy lifting there. It wouldn't disappear -- it has no where to go. It would just get very cold, which is essentially what you would expect of anything exposed to the vacuum of space. It wouldn't turn to ice, though, it would turn to vapor -- thus the "boiling". It would still, for any functional purpose, be a large amount of water lingering around the immediate vicinity of his head.
I kind of love you….
The pressure in space is essentially zero, so water boils instantly.
Yes, but boiling does not mean hot. It would be boiling at the same temperature, or cooler, as it was before the suit was opened
Much cooler. The heat of vaporization of water is 5.4x the calories to take the water from 0 C to 100 C. It's even a good multiple of the enthalpy of fusion. Most of the water would freeze if it stays in one place. I think it'd be roughly -50 C, based on some videos I looked up about vacuum chambers.
Can't imagine a boiling corpse would be very pretty.
Are you saying I could enjoy a spot of Earl Grey on my deathbed?
Tea. Earl Grey. Hot.
In an absolute emergency, you could probably get away with it for a few seconds. Just long enough to get some of the water out.
It takes several minutes for hard vacuum to actually kill you.
That's assuming it's even possible for astronauts to open their EVA suits while outside.
Assuming it is possible for astronauts to open their EVA suits... and close them back by themselves 😋
All while their blood boils and starts coming out of every orifice.
That's not what happens in real life. Vacuum will fuck with your bodily fluids, causing bruising and bleeding, but it won't explode out of you. The human body is actually pretty good at containing pressure.
Yep, the real risk is getting The Bends
You could poke a hole and then plug it if you wanted to. If you ended up just plugging it with whatever nearest, including skin, you would end up with a hickey but nothing else.
It’s not like poking a small hole in a space suit would cause instant decompression of the entire suit. The difference in pressure isn’t big enough for that. There was a 2mm hole on a spacecraft docked with the ISS, and it was determined that was no danger to the station and could easily be repaired
Right, that's what I'm saying. Pop a tiny hole in it, Watney-style, then the vacuum of space hopefully sucks the water out through it. When it's done, plug the hole again. If it gets bad again, open 'er back up!
Yeah, Canadian astronaut Chris Hadfield had something in his eyes during an EVA causing them to fill up with contaminated tears, essentially blinding him. Houston’s solution was for him to vent his helmet and suck the tears out into space.
I don't imagine the flash frozen water would be very nice though.
It would flash boil. Water boils at lower and lower temperatures as pressure decreased. That's why there are different cooking instructions on the back of the box for "high altitudes". Takes longer to cook something in Denver because things boil at a lower temperature.
In space the pressure is basically zero, so water just immediately boils.
Boil doesn't mean hot, however, whereas evaporation causes cooling. The rapid evaporation of some of the water would cause the rest of the water to freeze.
It would do both. Some of the water would flash boil, which would suck the heat out of everything around it, causing the rest of the water to freeze. Once the boiling stops you'd be left with a bunch of ice which would slowly sublimate away.
yo this makes so much sense. I visited a mountain town in colorado once for a ski trip and I was trying to boil some ramen on the stove. pacakge said like 3-4 minutes but it took me 7-9 minutes or more just to boil it properly! I thought the stove in the place I stayed at was just a low quality one.
The process of boiling is endothermic, meaning the boiling water would rapidly cool without a source of heat. Which is probably what they're referring to.
The water wouldn't freeze very quickly at all.
Vacuum isn't cold, it has an absence of temperature. There is nothing for the water to transfer its heat to directly, so it would only cool by radiation, which is slow.
The vacuum isn't cold, but the water trying to boil away in the low pressure would suck the heat out of anything it touched (since boiling takes energy), including the remainder of the water, which would cause it to freeze.
The energy required for the water to boil would come from the thermal energy of the water itself.
This is just not how fluids work. Boiling fluids do not suck the thermal energy from surrounding fluids to do so, that would defy rules of entropy.
This is literally how sweat works.
Entrophy isn't an issue because it would still take energy to revert to its original liquid form.
Sweat regulates temperature, it doesn't actively cool the body to lower than the temperature of the sweat. Your skin and sweat equalise in temperature until the sweat evaporates or is wicked away.
It's the same in all liquid cooling, the substance being cooled cannot be cooled beneath the temperature of the coolant.
Assuke the water in the space suit would be relatively consistent throughout its volume. The drop in pressure from being exposed to hard vacuum drastically decreases the amount of energy it needs to boil. So for each water molecule, some of its thermal energy will essentially be used to change state. It won't suck energy out of neighbouring particles to do so unless they are significantly hotter.
If the water were in a sealed chamber you might observe what you described, because the now cooler vapour would be contained with any remnants of liquid water. In open space however, the vapor would disperse too quickly for the vapor to take any meaningful amount of heat away.
I say this ironically while writing a report on the nitrogen cooled cryostat I made for a uni project.
>Your skin and sweat equalise in temperature until the sweat evaporates or is wicked away.
That doesn't even make sense. Your sweat literally comes from your body. It starts at the exact same temperature as your body. It can't take warmth from your body until it's the same temperature as the rest of your body since it was already at body temperature to begin with.
Sweating is entirely a form of evaporative cooling. Even the wikipedia articles says as much.
Buy a bottle of canned air and spray it. You can feel the bottle cool down dramatically to the point where it can cause frostbite as the compressed liquid inside turns to vapor. To the point where the bottle will stop working if you run it for too long.
Take a cooler full of ice, place a thermometer in it, and add salt. Since the ice will melt without heat being added the water will drop in temperature dramatically compared to the ice you started with.
Here is a god damn youtube video of someone freezing water by boiling it in a vacuum.
Again, it may work in a vacuum I an enclosed space where the vapour continues to be in contact with the liquid water. In open space the vapor would dissipate too quickly.
It's a vacuum in the video. The water vapor is being removed by the pump as fast as it boils. If it wasn't, it would stop being a vacuum.
Your skin and sweat are already the same temperature. Just as you say later on, thermal energy is used to change state to vapor. Because water and skin conduct heat, it will equalize and cool your skin.
Just plain circulating liquid cooling is a closed loop without a state change. Unless you are talking about refrigeration. Then compressed gas is hotter than ambient and then equalizes with surrounding air outside the radiator. And then when the refrigerant is depressurized, it has a lower thermal density than ambient air and can chill things.
Vacuum kills pretty quick. If you try holding your breath, you'll rupture your lungs, so the best thing to do is actually exhale before exposing yourself to vacuum. You can imagine this doesn't give you very much air left to live off of. You will lose consciousness within seconds, and you won't have much longer than that before you start suffering irreparable brain damage.
EDIT: I may be wrong about this; read the replies.
You generally have about three minutes before brain damage due to oxygen deprivation.
You'll also not lose consciousness that quickly. Most estimates give up to 30 seconds, which will depend on how oxygenated your blood is at the time.
> Vacuum kills pretty quick.
No, it doesn't. The overwhelming majority of instant death scenarios would be collapsing of the lungs. If not, you have consciousness for about 15 seconds since your bloodstream still has oxygen in it which we have evidence of, not to mention rough calculations of oxygen saturation in the blood.
If you still have your lungs though, it's estimated that you can survive in space for about 2 minutes without permanent damage (ie significant loss in function).
Though, with regards to brain damage - generally you can survive 5-10 minutes deprived of oxygen without significant loss of brain function. The upper limit of avoiding brain death from oxygen deprivation is around 20 minutes.
However the dangerous bit here is primarily that you'd be on a spacewalk, meaning it would be near impossible to retrieve you in time. Not only does putting on a spacesuit take a significant amount of time, but they operate at a far lower atmospheric pressure than the space station, so they'd be fighting severe decompression sickness at the same time. It's hard to say though, because I don't know if they have any sort of procedure for that type of thing.
Not true, you’d have explosive decompression and lose consciousness within seconds. It isn’t like holding your breath. The air is sucked out of you instantaneously.
Explosive decompression really isn't a thing. You need pressure differentials much higher than one atm to cause that sort of force.
Air isn't sucked out of you instantaneously, that's not how fluid dynamics work, you'd need a much higher differential for it.
Estimates generally give about 15-30 seconds before loss of consciousness, depending on how oxygenated your blood is.
I’m not going to pretend I’m an expert on pressurization but I am an airline pilot and our charts agree with Wikipedia that it’s about 6-9 seconds of useful consciousness.
There's a handful of cases where people were exposed to a total vacuum for a short period and survived. Here's one of them -- he was mostly unharmed.
The reason explosive decompression can be a thing in a plane but not in space is because of the force of outside air acting on things inside of the vehicle. If something acts on an air plane to abruptly depressurize it through a sufficiently large enough hole, it isn't so much that things are "sucked" out of it as it is that things are "blown" out of it. It is the same force that makes it feel like something can get sucked out of a car window when your vehicle is in motion even though there isn't actually a meaningful pressure difference between your closed car and the outside air, it has to do more with the motion of the air along the vehicle.
In a vacuum things like gasses (air) would expand outwards through a breach, but there isn't the same force acting on a space shuttle that there is on a vehicle in motion on Earth, the popular media idea of things getting explosively decompressed out of a spaceship wouldn't actually happen outside of the force of whatever caused the breach to occur in the first place.
The force exerted by air expanding into a lower pressure area, like what would happen if you "opened the car door" so to speak, but in outer space, isn't enough to actually "suck" things out of the vehicle. Except probably really light things like paper or something, depending on how abrupt the breach was and how big (or, small) it is. You'd basically have to get sucked through a garden hose to generate enough pressure to drag a human body out of a spaceship -- and in that specific theoretical you'd block the opening with your clothing or just the weight of your body far before any actual bodily damage would occur. It probably wouldn't be fun to experience but you'd survive and with all your limbs.
TIL, thanks!
Viewing a single comment thread. View all comments