Why do astronauts wear helmets? And what would happen if they took off their helmets in space?
Astronauts wear helmets in space because otherwise they would not be able to survive. This is because there is no air pressure and no oxygen in space. Both are essential for the survival of the human body.
If an astronaut were to remove his or her helmet in space – that is, outside a space station or capsule – he or she would lose consciousness within a few seconds and die shortly thereafter. This is because there is a vacuum in space and therefore no air pressure there.
Why is air pressure so important for our bodies?
Similar to how water pressure is vital for deep-sea fish, humans need air pressure to survive. A deep-sea fish’s organism is designed to function under high water pressure – if you bring it to the surface, it dies and turns into an unrecognizable heap. This is because its cells expand and burst due to the lack of pressure.
The same thing happens to humans when there is a sudden lack of air pressure – which is what would happen if an astronaut were to remove his or her helmet outside a space station. This is because air pressure ensures that there are sufficient amounts of oxygen in the air to keep our bodies and brains well supplied. This is why mountaineers often need oxygen tanks at high altitudes: Because due to the lower air pressure at these high altitudes, there is also less oxygen available in the air, which leads to a poorer supply of oxygen to the brain and muscles and, in the worst case, causes unconsciousness.
At the same time, the air pressure ensures that the gas in our bodies, lungs and blood vessels is exactly the size we need to survive.
If now – as in the case of astronauts who suddenly remove their helmets – the air pressure were to drop rapidly, this would cause all the gases present in the body to expand in one fell swoop. This, of course, also happens to all the gases in the lungs and alveoli, which would cause both the alveoli and the lungs themselves to burst. This is not only extremely painful, but also acutely life-threatening, as the body can now no longer take in oxygen.
At the same time, the oxygen present in the blood also expands, bursting the blood vessels and causing severe internal bleeding. This is also fatal without immediate medical attention.
Is there a way to survive in space without a helmet and suit?
Not outside a space station, space capsule or rocket.
Even if it were somehow possible to survive the vacuum in space and the resulting consequences due to a lack of air pressure for the body, one would either suffocate due to the lack of oxygen in space or die due to the extreme temperatures in space.
Depending on the distance to the sun, extremely high or extremely low temperatures prevail in space, which would cause an astronaut to either freeze to death or burn up without the necessary protective equipment. Especially the extremely high temperatures are a problem even for astronauts with suits and the reason why no human has ever been on Venus or near the sun.
Last but not least, without a suit and helmet, one would be defenceless against the often radioactive radiation in space, which would also lead to death sooner or later.
Another reason why survival without protective equipment in space would not be possible is that liquids would evaporate or vaporize rapidly. This would dry out the human mucous membranes, which would first destroy the eyes, nose and mouth. The resulting exposed mucous membranes in the throat would also cause the trachea and esophagus to dry out and thus be destroyed. Breathing would therefore no longer be possible even if the astronaut were to put his or her helmet back on.