5 Horrific Ways You Would Actually Die in Space

Over the years, Hollywood has offered us some spectacular death scenes in space. Flash freezing, explosive depressurization – they make for some memorable final character moments, but just how realistic are they?

Here are five ways you would actually die in outer space.

1. Asphyxiation

Let’s get the most obvious one out of the way first. There’s no air in space, so you would asphyxiate. Even parodies of bad 1940s sci-fi movies like The Simpsons’ “The Planet from Outer Space” manage to get this one right. But what may shock you is just how quickly you would asphyxiate.

To understand that, though, we need a crash course on the human respiratory and cardiovascular systems. You breathe air into your lungs; within your lungs are tiny air sacks called alveoli which have walls so thin that gases can pass through them; the high pressure of air inside your lungs sends gas through the alveoli walls; the alveoli are close to tiny blood vessels called capillaries; through a process called diffusion, the alveoli pass oxygen into the oxygen-depleted blood in the capillaries; finally, the oxygenated blood is pumped throughout your body, allowing your cells to function properly.

If cells can’t function properly due to lack of oxygen, they will begin to die. The brain, for instance, can go as little as three minutes without oxygen before cells begin to die. But in space, you would actually die in a fraction of that time. Why? Read on…

2. Rapid Decompression

Most people have heard of “the bends,” that condition that deep sea divers get if they resurface too quickly – another Hollywood staple. Officially known as decompression sickness, this condition occurs when your body suddenly moves from a high-pressure environment to a low-pressure one. The lower pressure causes dissolved gases to expand into bubbles inside your body, and depending on where these bubbles form, the results can be fatal.

Since space is a vacuum, it is the lowest-pressure environment imaginable – there are no air molecules, so there is nothing to exert pressure on your body. While that doesn’t mean you would explode, like some movies would have us believe, it would lead to swelling. Human skin is sturdy and elastic enough to prevent us from popping like a balloon – Total Recall‘s inflating heads may be an exaggeration.

Rough estimates suggest a human can survive for up to 90 seconds in a vacuum, but would lose consciousness after about 15 seconds. This ties back to asphyxiation – the low pressure outside the body would cause oxygen to rapidly leave the blood. And if you tried taking a deep breath before hopping out into space, your lungs would likely pop during the rapid decompression, since they’ve already expanded as far as they can go.

3. Extreme Temperatures

Let’s pretend you’re somehow able to survive the lack of oxygen and the low pressures. Space is cold, right? That’s why Tim Robbins’ face flash-freezes when he removes his helmet in Mission to Mars, right?

Wrong. Space isn’t cold – space has no temperature. It’s just that – space. Empty space. Nothingness. When we say that air has a temperature, we’re referring to the gas molecules, not the empty space around them. Objects in space will have a temperature, and that temperature will depend on external and internal heat sources.

Your body produces heat to maintain itself at a certain temperature. Stay outside in the cold on a winter night, and your heat will dissipate into the surrounding cold air. Cold air molecules come in contact with your skin, and heat is transferred away from your body.

In space, there are no air molecules. That means you would only lose heat through the much slower process of radiation. Just like a star, a human being radiates energy – but our lower body temperatures mean that most of the energy we radiate away is in the form of infrared light, invisible to the naked eye. The amount of energy we radiate away is about 100 watts – the same as a light bulb.

Now, if you were in a planet’s shadow for a long time, away from any heat sources, you would probably freeze to death after a while. But if you were out in the open, exposed to direct sunlight, you may actually die from overheating.

4. Micrometeoroids

No, these aren’t tiny hemorrhoids – but you should get those checked out as well. A micrometeoroid is a tiny particle of rock hurtling through space at around 5 miles per second. While most are the size of dust grains, anything moving that fast is going to pack a punch behind it – think of how powerful a sandblaster is, then consider that a sandblaster blows sand orders of magnitude slower than a micrometeoroid moves.

Micrometeoroids are considered a big enough threat that significant attention has been given to designing spacecraft and space suits that can limit the amount of damage these little buggers cause. Most micrometeoroid damage is a slow, weathering process that erodes away at material, but all it takes is one slightly larger particle to cause catastrophic damage. These particles are out there – it’s just a matter of when you’ll win the lottery and get your skull pierced. The film Gravity delivered a dramatic portrayal of the dangers of space debris.

5. Radiation

We’ve thoroughly discussed this in the past: radiation doesn’t give you superpowers, regardless of what the Fantastic Four tells you. That is, unless you consider cancer to be a superpower.

High energy photons from the sun and other subatomic particles issuing from deep space are constantly bombarding the Earth, but our planet’s magnetosphere protects us. You see, the Earth is surrounded by a magnetic field that is generated by the motion of molten metals in its core. This magnetic field deflects most of the incoming harmful particles that would otherwise damage our DNA.

Outside of the Earth’s protective shield, short-term exposure to these particles can cause cancer, and prolonged exposure can lead to death by organ failure. It may not be a spectacular Hollywood-worthy death, but it’s probably the worst of these ways to die.

What’s your favorite fictional depiction of death in space? I’m particularly fond of Ripley blasting the xenomorph into space in Alien.