A Disturbing Death in Outer Space

A look at how the vacuum of space will kill you

Ella Alderson
May 29, 2018 · 6 min read

Only three people have ever died in space. The crew of the Soyuz 11 consisted of three men who had spent 22 days at the Salyut 1 Space Station. On the last day of June in 1971 an open valve on their space craft exposed them to the vacuum of space and they were all dead in under a minute. Their bodies were found with blue patches on their faces and with traces of blood coming from their nose and their ears.

It’s been over 40 years since anyone has died in space. Most astronauts’ deaths don’t actually occur in what’s officially defined as outer space but instead happen during the launching and re-entry of the craft. The lack of deaths in space itself comes from careful protocols and our growing understanding of how to keep humans safe and healthy during space flight. Therefor, most of what we know about how the vacuum will affect our bodies comes from experiments done here on earth where scientists have simulated the same conditions of the vacuum and have used animal and human test subjects.

The truth is that maintaining a human alive in outer space at all is miraculous. There’s not only the question of food, gear, water, and medical supplies, but the very act of being outside of the gravitational pull of Earth is unhealthy and very disruptive to our bodies which were designed for the atmosphere and gravity of our planet.

Because of this, in as little as a few days 10–15% of the mass of blood inside your body disappears due to the lack of gravity that usually works with our circulatory system. Our immune system also becomes compromised and there can be a significant amount of muscle loss even with the required two hours of daily exercise that each astronaut must maintain. According to NASA statistics, 1–6 months in space is enough to decrease muscle volume by 13%. They’ve also noted a loss of bone density and a temporary increase in height. The disks between the vertebrae of the spine can expand since there’s no gravity compressing them down and this allows a small growth spurt that’s reduced back down again once the astronauts have returned to Earth. The fluid shift also means that the body shape begins to even out more, causing the legs to grow thinner and the face to get rounder.

Being in outer space is such a drastic change for our bodies that we’re not even sure it’s possible to reproduce outside of Earth. Changes in blood flow would make sex difficult and could have a significant impact on pregnancy. There has never been any recorded instance of sex in space but it is something to think about if we want our species to survive and continue on outside of Earth.

When you couple all this with the fact that it costs about $1k per pound of gear to get it into space, you’re already starting with an expensive and complicated endeavor.

The space suit is extremely important to keeping people alive in the vacuum of space. It’s more formally known as an EVA or an extravehicular activity suit. They account for a number of problems, such as urinating and keeping the body cool while someone is inside the suit. Using liquid cooling, tubes run water along the skin to keep it cool while fans are also built into the suit for the astronauts to use. There’s built in drinking bags that can hold up to 32 ounces of fluid and have a connected straw.

A lot of injuries in space are actually because of the space suit’s gloves. They can be so heavy and can exert so much pressure that astronauts’ fingernails will fall off.

So what happens if someone is exposed to the vacuum of space?

The first thing is don’t hold your breath. The loss of external pressure means that all the air inside of your body would immediately rush outward from every orifice, including the air in your intestines. Every dog used in tests in labs defecated themselves as the gases left their bodies. If you did attempt to hold your breath, your lungs would expand and rupture.

Within 10 to 15 seconds you will be unconscious as oxygen will no longer be getting to your brain. Eventually, you’d suffocate, though you might be okay for up to 3 minutes without air. During the studies it really came down to chance. Some animals were able to go 3 minutes in the vacuum and recover completely with no cognitive damage. Others died long before that. Some chimps and dogs, for example, were fully recovered with 10 minutes of being rescued.

The loss of pressure would not only knock you out, but it would also cause all the blood vessels on the surface of your body to break, even those in your eyes. Your eyes, however, would not pop out of your head, nor would you explode the way sci-fi films would have you believe. This is because your circulation is part of an enclosed system and is still being regulated inside your body.

Also unlike in those films, your blood would not boil inside your veins. However, any fluids exposed to the vacuum would boil due to the extremely low pressure. This allows the fluids — like saliva and sweat — to boil at body temperature, though it wouldn’t be painful. Here “boiling” merely means that the liquid changes state into a gas.

Your skin would stretch and swell and feel like pins and needles for a while. All exposed skin would suffer extreme sunburn since there’s no protection from radiation in space. Earth keeps us safe with the equivalent of a meter-thick layer of protection from the UV of the sun but that’s a luxury astronauts don’t have.

While the universe is very cold (-270.45 degrees Celsius, actually), you wouldn’t actually freeze to death because there’s nothing your body can transfer its heat to. Thermal conduction needs another object to take the heat from your body but in this case, because it is a vacuum, there is nothing.

What if an astronaut floated away from the spaceship? Well, there’s currently no rescue vehicles available to go retrieve them. They would continue in the direction of the force that had pushed them away to begin with. The Earth could trap them in orbit for up to eight hours if they had a full tank of oxygen. A bleak but undeniably beautiful death.

Another thing about running out of oxygen is that your body wouldn’t decompose the way it does here on Earth. Your body might mummify if it’s near a source of heat but otherwise it might be floating in space for millions of years with nothing to decay it.

Physics student. A passion for language and the mysteries of our universe, our future, and our human condition. I can be reached at ella.aldrsn@gmail.com

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