What Happens To The Human Body In A Vacuum?

135859main_moon-concept-3.jpg
A NASA artist concept of future crews living and working on the Moon. NASA/Davidson

As humans get closer to living and working in space for long periods of time, a lot of questions arise about what it will be like for those who make their careers "out there". There is a LOT of data based on long-duration flights by such astronauts as Mark Kelly and Peggy Whitman, but it's still a very active area of study.  The long-term inhabitants aboard the International Space Station have experienced some major and puzzling changes to their bodies, some of which last long after they are back on Earth.

Mission planners are using their experiences to help plan missions to the Moon, Mars, and beyond.

However, despite this priceless data from actual experiences, people also get a lot of non-valuable "data" from Hollywood movies about what it's like to live in space. In those cases, drama usually trumps scientific accuracy. In particular, the movies are big on gore, especially when it comes to depicting the experience of being exposed to vacuum. Unfortunately, those movies and TV shows (and video games) give the wrong impression about what it's like to be in space. 

Vacuum in the Movies

In the 1981 movie Outland, starring Sean Connery, there is a scene where a construction worker in space gets a hole in his suit. As the air leaks out, the internal pressure drops and his body is exposed to a vacuum, we watch in horror through his faceplate as he swells up and explodes.

A somewhat similar scene occurs in the 1990 Arnold Schwarzenegger movie, Total Recall.

In that movie, Schwarzenegger leaves the pressure of the habitat of a Mars colony and begins to blow up like a balloon in the much lower pressure of the Mars atmosphere, not quite a vacuum. He is saved by the creation of an entirely new atmosphere by an ancient alien machine.

Those scenes bring up an entirely understandable question:

What happens to the human body in a vacuum?

The answer is simple: it won't blow up. The blood won't boil, either. However, it will be a quick way to die if an astronaut's spacesuit is damaged or a space worker isn't rescued in time. 

What Really Happens in a Vacuum

There are a number of things about being in space, in a vacuum, that can cause harm to the human body. The unfortunate space traveler wouldn't be able to hold their breath for long (if at all), because it would cause lung damage. The person would probably remain conscious for several seconds until the blood without oxygen reaches the brain. Then, all bets are off. 

The "vacuum of space" is also pretty darn cold, but the human body doesn't lose heat that fast, so a hapless astronaut would have a little time before freezing to death. It's possible that they would have some problems with their eardrums, including a rupture, but maybe not. 

Being marooned in space exposes the astronaut to high radiation and the chances for a really bad sunburn. The body might actually swell some, but not to the proportions so dramatically shown in Arnold Schwarzenegger's movie, Total Recall. The "bends" are also possible, just like what happens to a diver who surfaces too quickly from a deep underwater dive.

That condition is also known as "decompression sickness" and happens when dissolved gases in the blood stream create bubbles as the person decompresses. The condition can be fatal, and is taken seriously by divers, high-altitude pilots, and astronauts. 

While normal blood pressure will keep a person's blood from boiling, the saliva in their mouth could very well begin to do so. There's actually evidence for that happening. In 1965, while performing tests at the Johnson Space Center, a subject was accidentally exposed to a near vacuum (less than one psi) when his space suit leaked while in a vacuum chamber. He did not pass out for about fourteen seconds, by which time unoxygenated blood had reached his brain. Technicians began to repressurize the chamber within fifteen seconds and he regained consciousness at around the equivalent of 15,000 feet of altitude.

He later said that his last conscious memory was of the water on his tongue beginning to boil. So, there's at least one data point about what it's like to be in a vacuum. It won't be pleasant, but it won't be like the movies, either.

There have actually been cases of parts of astronauts bodies being exposed to vacuum when suits were damaged. They survived due to quick action and safety protocols. The good news from all those experiences is that the human body is amazingly resilient. The worst problem would be lack of oxygen, not lack of pressure in the vacuum. If returned to a normal atmosphere fairly quickly, a person would survive with few if any irreversible injuries after an accidental exposure to vacuum.

Edited and updated by Carolyn Collins Petersen.

Format
mla apa chicago
Your Citation
Greene, Nick. "What Happens To The Human Body In A Vacuum?" ThoughtCo, Oct. 26, 2017, thoughtco.com/human-body-in-a-space-vacuum-3071106. Greene, Nick. (2017, October 26). What Happens To The Human Body In A Vacuum? Retrieved from https://www.thoughtco.com/human-body-in-a-space-vacuum-3071106 Greene, Nick. "What Happens To The Human Body In A Vacuum?" ThoughtCo. https://www.thoughtco.com/human-body-in-a-space-vacuum-3071106 (accessed December 14, 2017).