How do spacesuits work?


My kid has been asking me what happens to austronauts if they take their suits off in space. I cant explain it properly since I’m not entirely sure too.

In: 117

Like you’re five:

Air is all around you. It is squeezing your skin.

When you breathe, little bubbles end up in your blood – so tiny you can’t see them – like bubbles in a soda bottle that’s sitting still.

To go to space, where there is no air, we need to keep those bubbles small, so we wear a suit inflated with air.

If you take off that suit, the little bubbles get bigger – just like opening the top of a soda bottle. When they get bigger, they can break open your arteries and veins – like a rapid bruise happening on the inside and outside of your body. This means in your skin, muscles, fat, bones, and organs. It will kill you.

This doesn’t even get into the idea that the air in your lungs would want to quickly leave your body and cause you to suffocate pretty quickly.

Add the need for keeping your body temperature normal and you realize these suits are super important!

There is no air in space, and therefore zero air-pressure.

We need air and air-pressure to stay alive. The suit is pumped up with air like a balloon until it is 1 atmosphere of air pressure, the same as the surface of earth. Then the astronaut can breathe normally inside the suit and special machines in the suit take away the stale air and pump in fresh air.

If they took the suit off, all the air would rush out like if we cut the balloon. The Astronaut would get very cold and couldn’t breathe, and the liquids in their body would either boil or freeze which would kill them.

Remember that the atmosphere was here before we were. So instead of being crushed by the weight of the atmosphere, we have developed to “push back” by the same amount. Remove the atmosphere so there’s nothing to balance our “push out” against, and we go pop.

A balloon, inflated on Earth, will pop in space. Next time you’re near a 20+ floor building, take a balloon. Inflate it a ground level and take a photo (next to your head for size comparison). Take the elevator to the top floor and take another photo. The balloon is bigger because there is less atmosphere holding it in. Back at ground level, the balloon is back to “normal” size.

You body needs a certain amount of outside pressure to stay functional and you also need air to breathe. A spacesuit provides both by being a solid object that holds air inside of it at a safe pressure – basically its a giant balloon that has a person inside of it.

A secondary, but still very important, requirement of spacesuits is temperature regulation. Vacuums, and thus space, are odd in that it is both really hot and really cold at the same time. Without thermal regulation systems, a part of your body in sunlight would cook while the other side in the shade would freeze. To solve this problem, the suit needs the ability to circulate heat around, both cooling down areas in sunlight and heating areas in shade. In many cases during long duration spacewalks, enough of the suit will be in the sun to require the suit to have some way to radiate heat out – the human body should enough heat to keep it warm in the shade. Typically, this is done by having water pumped through the suit.

Some additional things that the suit needs to help deal with:

* Water and food. Spacewalks typically last a long time, and the astronaut will need to drink, and sometimes even eat. They cannot reach their face, so the suit needs tubes they can eat or drink from.
* Sweat. You cannot wipe your face, and the lack of gravity suits are normally operated under means the water won’t drop down. Without some method of handling this, an astronaut would eventually drown in their own sweat. It would also be very problematic if sweat got into their eyes – you’ve probably experienced that, but now imagine not being able to wipe your eyes to help either. Naturally, this would not be an issue if you had no spacesuit on – the sweat would just evaporate very quickly.
* Other body waste. A spacewalk likely lasts hours and it can take 15 minutes or longer to don and doff the suit, so the astronaut needs some way to go to the bathroom inside the suit. This is typically done by using a diaper, though a few other methods have been used but are often not practical. Naturally, this would not be an issue if you had no spacesuit on – the products would float away, and urine would tend to evaporate very quickly.


Not a huge amount is known about what happens if a person is directly exposed to a hard vacuum as doing so is very dangerous, even for short periods, however [an accident]( has revealed some information.

A few things of note. mostly from that incident:

* The human skin, eyes, and blood vessels can maintain enough pressure to keep your body intact and properly shaped. You wouldn’t explode or experience severe bleeding.
* You may get a nosebleed as the blood vessels in the nose are small and close to the surface. As with any nosebleed, the blood should clot and stop the bleed reasonably quickly.
* The pressure drop is not enough to cause the [bends](, which is where the tiny nitrogen bubbles that are always in your blood expand and cause major health problems.
* The pressure *will* cause exposed water to boil. This includes the salvia on your tongue and the mucus in your airways. This will *not* cause burning as the water is only at body temperature still.
* Depending on the speed of decompression, hearing damage can occur. In most cases, the pressure drop will be small enough or slow enough to limit this to just a temporary ear ache.
* It is impossible to hold your breathe, though no harm will occur from trying. The vacuum will effectively suck the air out of your lungs despite you best ability to hold it in. When blood passes the air exchange system in your lungs, it will even suck the oxygen out of your blood like it normally sucks the carbon dioxide out. This means you will run out of oxygen much faster than you would from other causes of asphyxiation.
* You will remain conscious for about 15 seconds. Most people will begin to lose function sooner.
* After about 30 seconds, major effects of oxygen starvation occur, including brain damage.
* Death will normally occur after about 90 seconds.
* You would not freeze solid for quite a long time – likely between 12 and 26 hours. The human body contains a lot of heat energy, and is constantly producing heat which would keep you warm until death (and decomposition will produce some heat after), especially when the only way you are losing heat is via infrared radiation – you are surrounded by what is basically the best possible insulator. And that is even without considering the radiation you would absorb from the sun.

Also, as a note, [NASA has a document]( (PDF warning, and nearly 100 pages) that you may want to read over, which includes some kid-friendly activates you can try relating to space suits and high-altitude suits. Some of the activities can be easily done at home, while others require equipment you probably won’t be able to get cheap enough to be worth it. You can also see if a nearby science museum or school has the equipment.

Humans are big sacks of slushy stuff. That stuff requires two things to stay as is and not turn into messy stuff: temperature and pressure.

You know how you can crush a soda can if you were to suck the air out of it? Exact same thing with a human body. The can is crushed because you just removed air from the inside, and the air outside of it has pushed inwards at such a force the can is crushed.

Our bodies are designed to function under standard pressure. Take away that pressure and there’s trouble. You know how your skin turns red and starts inflating if you were to hold a tube syringe against it and pull the plunger? Same thing in space, except everywhere on your body and at a much more severe level.

That’s the pressure part of a spacesuit, we just ensure the astronaut’s body is surrounded by a mass of air at the same pressure as here on earth. The temperature part is simpler, we just heat that air up to a comfortable temperature so we don’t freeze in space.