How Long Can You Survive in Space Without a Suit?

How Long Can You Survive in Space Without a Suit?

How Long Can You Survive in Space Without a Suit?

If you’ve seen sci-fi movies in space, you may be familiar with the scenes exposing people to the endless vacuum of space. Pop culture tells us that this never ends well. We see people freezing solid immediately, exploding and swelling like balloons, their blood boiling, or maybe even a combination. What we’re trying to get at is that pop culture has tied the idea of being unprotected in space to immediate death. But what really happens when you’re exposed to space without a suit? Can you survive at all? If so, for how long?

You’ve probably guessed by now that yes, you can survive in space without a suit. In fact, you can survive quite a bit longer than you might think. But before we break down how you could go about surviving the perils of space, let’s go through some of the governing principles. 

Some Fundamental Laws

Ideal Gas Law

Let’s start with the fact that space is a vacuum. If you go to YouTube and watch a video of a balloon in a vacuum, you’ll see it expands. So, it stands to reason that if you were in space you’d just pop. But why exactly does the balloon expand in the first place?

If you’ve taken middle/high school chemistry, you may remember learning about the ideal gas law. The full expression is PV = nRT, where P is pressure, V is volume, n is a representation of how many molecules you have, T is pressure, and R is a constant. For the purposes of this article, we are primarily concerned with the PV part, and not the nRT part. We’ll explain why in a second.

Balloon in a Vacuum

When you have the balloon in a vacuum, you have three systems. The balloon, the vacuum the balloon is in (without the balloon), and a system with both the vacuum and the balloon. Each of these three has their own independent application of the ideal gas law. The third system we listed (the one with the balloon and vacuum) represents a state where the first two systems (balloon vs vacuum) are in equilibrium. Basically, the pressure inside the balloon and the pressure of the vacuum are equal (or close enough to). 

With some algebra, we can determine that PV / T (Vacuum) = PV / T (Balloon). The temperature between the vacuum and balloon is the same, so PBalloonVBalloon = PVacuumVVacuum. After more algebra, we determine the balloon’s pressure is inversely proportional to the vacuum’s volume and vice versa. Ergo, when the vacuum’s pressure decreases, the balloon’s volume has to increase (the balloon expanding is it increasing its volume).

You could also see it as the pressures are trying to be equal, so as the vacuum’s pressure decreases, so does the balloon’s. The balloon can’t decrease pressure by shooting air out of itself, so it expands to decrease its internal pressure.

Boiling at Low Pressure

Most things can exist as either a solid, liquid, or gas. You might be familiar with water, it boils at 100 degrees Celsius. But did you know that you can make water boil below that temperature? Basically you put the water in a low pressure environment, and it lowers the temperature at which it boils. In short, if you make the pressure low enough, you can make a liquid boil without ever making it hot. Remember this; it is important.

This is a crude construction of water’s phase change diagram. Pick a temperature and a pressure, and plot that point on this graph. The section that point is in determines whether it is a solid, liquid, or gas. So you can see a low enough pressure at any temperature makes water a gas.

What Would Happen to You in Space?

Given what we’ve just told you, you popping would be a fairly reasonable description. Balloons pop in vacuums, and when you’re in the vacuum of space you’re a symbolic balloon.

Your skin is actually elastic enough to not rip like this, but you would get a little bloated though. Yes, you will expand a bit. Your lungs, on the other hand, are not that elastic. Fun fact, the balloon example is how you breathe. When you breathe in you increase the volume of your lungs which creates a low-pressure environment the air outside will rush in to fill.

Anyway, if you hold your breath and don’t let the air out, your lungs become the balloon. In this case, your lungs will rupture and you’re not going to make it. This is why divers are instructed not to hold their breath when they ascend, since the immense water pressure is dropping relatively quickly. 

So let’s assume you didn’t hold your breath. This means all the gas and loose things inside you will want out of your body to equalize the pressure environment. Don’t worry, by loose things we don’t mean organs. We mean food. So you would exhale all the air inside of you almost instantly, and then you would vomit and soil yourself (from both ends) simultaneously. It would be really gross, but you would be alive.

You’d also get a space version of the bends. This happens to divers if they ascend too quickly, but basically it results from the liquids inside you turning into gas. Remember earlier when we said liquids can boil at super low pressures? Yeah, the vacuum of space is dang near zero pressure, so the liquids inside you are going to start becoming gas. You can make a recovery from this (it’s not gonna be fun). 

How Long Would You Last Without a Suit in Space?

So the blood boiling we just talked about won’t end you very quickly. Same with it being either really hot or really cold in space–you won’t die immediately. What gets you in the end is just suffocation, since all the air in your lungs is out in space and it’s not going to get back into your body.

In that case, you would go unconscious in about 15 seconds (that’s how long your brain can go conscious without oxygen). You’d go temporarily blind as the water on your eyes vaporized away, and you’d vomit and soil yourself. Your body would swell a bit too like a balloon, almost comically so. Then you’d have about 3 minutes before your brain shut down due to lack of oxygen and you realistically couldn’t be saved anymore. 

How Do We Know This?

Fortunately, we’ve never shot a person into space before just to see what happened. We did put dogs and chimpanzees into a vacuum chamber once, though. That’s far less fortunate. But the dogs exposed to the vacuum for around 3 minutes all made a pretty good recovery, and those under 2 minutes made a full one. 

There was also the time Jim LeBlanc was accidentally exposed to a vacuum without a pressurized space suit for a very quick stint. In the end, he survived with nothing more than an earache. He was exposed for an extremely short period of time, but the point stands that you will not immediately die in a vacuum.

So in the end, to distill everything down:

  • You will be conscious for about 15 seconds 
  • You will probably not last more than 3 minutes due to suffocation
  • Liquids inside you will become gaseous and you will probably experience something similar to decompression sickness
  • You probably will go blind until re-pressurized
  • You probably will swell
  • You probably will throw up, defecate, and urinate at the same time

Sporcle does not condone nor wish to see self-conducted experiments of our readers launching themselves into space. Proceed into the cosmos with caution.

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