As a space science expert, I'd like to delve into the intricacies of breathing in space. The human respiratory system is designed to function within the Earth's atmospheric conditions, and the ability to breathe is contingent upon several factors, including air pressure, composition, and the presence of oxygen.

On Earth, we breathe by inhaling air that is composed of roughly 21% oxygen, which is essential for our body's cells to produce energy. Our lungs expand and contract, facilitating the exchange of gases between the air we breathe and the bloodstream. The atmospheric pressure at sea level is about 1 atmosphere (atm), which is the pressure required for our lungs to efficiently perform this gas exchange.

In space, the situation is vastly different. The vacuum of space lacks sufficient air pressure and oxygen to support human life. The absence of air pressure means that the gases in our bodies would rapidly expand, leading to a condition known as ebullism, where bodily fluids would begin to boil at body temperature. Furthermore, without oxygen, we would quickly succumb to hypoxia, or oxygen deprivation.

However, astronauts are not left to the mercy of the space environment. Spacecraft and space suits are engineered to mimic the conditions necessary for human respiration. These closed-loop systems maintain an Earth-like atmosphere with a balanced mixture of gases, including oxygen, and at a pressure that is safe for human lungs. The International Space Station (ISS), for example, is pressurized to approximately 0.97 atm, which is slightly lower than Earth's atmospheric pressure but still within a breathable range for humans.

The space suits worn by astronauts serve a similar purpose. They are designed to provide a life-supporting environment around the astronaut, ensuring that there is enough oxygen to breathe and that the pressure is regulated to prevent the dangerous effects of decompression. These suits are also equipped with carbon dioxide scrubbers to remove the waste gas produced during respiration, thus maintaining a breathable atmosphere.

It's also important to note that the absence of gravity in space does not directly affect our ability to breathe. While gravity does play a role in the circulation of air and fluids within our bodies, the primary concern for breathing is the presence of a breathable atmosphere. As long as the air around us is thick enough and contains the necessary gases, we can breathe, regardless of gravity.

In summary, while the vacuum of space is inhospitable to human life, the technology developed for space exploration has made it possible for astronauts to breathe and live in space. The key to this is the creation of a controlled environment within spacecraft and space suits that replicates the conditions necessary for human respiration.

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We breathe by expanding our lungs. ... As long as the air around us is thick enough we can breathe, regardless of gravity. On Earth, gravity is what holds our atmosphere. When astronauts go into space they can breath, because their space ships and space suits keep the air around them, even though gravity is very weak.read more >>