We have seen, in many Hollywood films, astronauts who die in space or that are exposed to the vacuum. Do they really freeze instantly? Do the blood boil? The body explodes? None of this! We know for certain that we die in the vacuum because of lack of oxygen, but what else happens?

The vacuum is considered to be the total absence of matter (visible or invisible) in a given region. This includes gases (such as oxygen) that are responsible for our survival. Therefore, the vacuum is not safe for those without a space suit. At first, oxygen is expelled from the lungs, causing the loss of consciousness (due to lack of oxygen in the brain) in about 15 seconds. After that, it will not take more than two minutes for the organs to stop working and the person to die.

NASA says, on its official website, that in 1965 an accidental experiment with humans occurred in a vacuum. During a simulation, the costume of an astronaut (whose name is not disclosed) was torn. He became conscious for 14 seconds and then fainted. Soon after, the depressurising of the simulator was started and he survived. Following the report, NASA says that when it regained consciousness, the astronaut said he heard oxygen coming out of his body, just as he felt a lot of water on his tongue and the feeling that it was boiling.

What if I hold my breath?

If the person didn’t try to hold his breath, he would have a chance of surviving around 30 seconds without permanent damage. Holding air in the lungs could cause much greater damage. This is the reason why divers have to take care when returning to the surface. When they are submerged, the lung contracts because of the pressure. When they begin to emerge, the lung begins to return to normal size. The problem occurs because of the water itself! The gases – in this case, inside the diver’s lung – tend to dissolve in liquids when there is a reasonable pressure difference. When it emerges, the pressure difference decreases and the diluted gas begins to form air bubbles in the person’s veins.

Freezing, boiling blood and other myths

It is really possible that the blood undergoes abnormal reactions in the vacuum, but inside the body it would never boil. Still in the veins and arteries, the blood doesn’t obey the physical laws that apply to the vacuum and, therefore, doesn’t react like it would in an environment without matter. Another myth is with regard to the temperature in the vacuum. If the subject was in the shade, the temperature would drop sharply. But of the three types of heat exchanges (conduction, heating and radiation), only the radiation occurs in the vacuum, in addition to being very slow. You literally would die before freezing.

 

Now, if the individual was looking at the sun, the burns due to the lack of filtration of the UV rays would be absurd (because there is no atmosphere). A much-remembered movie scene is from “The Avenger of the Future,” starring Arnold Schwarzenegger, when he appears without a safety suit, on a remote planet, and his eyes explode. This is impossible because there is not enough pressure in the human body to cause it.

However, only three people have died from exposure to the vacuum. In 1971, Soyuz 11, which carried three Russian astronauts, underwent decompression during re-entry while still in space. The accident resulted in the death of the three crew members. When the ground crew arrived at the landing site, it found all three in a state that was defined as “seemed to be sleeping.”

And after death, what happens to the body?

Suppose, therefore, that a person is exposed to space and dies there, without protection. The body also would not decompose the way we think, since there is no oxygen. If it were near a source of heat, for example, the body could mummify. Otherwise, it would freeze. However, if the body were inside an astronaut’s outfit, it would start the decomposition process until oxygen supplies ran out. Whatever the condition, the body in space would last much longer without air, which is a factor that greatly facilitates degradation. The corpse could float through the vast expanse of space for millions and millions of years.