How do divers and astronauts manage gas behaviour under different pressures?

Divers and astronauts manage gas behaviour under different pressures through careful regulation of gas mixtures and pressures.

Divers and astronauts operate in environments where the pressure is significantly different from the normal atmospheric pressure at sea level. This change in pressure can have a profound effect on the behaviour of gases in their bodies and equipment, which they must manage carefully to ensure their safety.

For divers, the main concern is the increased pressure experienced underwater, which can cause gases to dissolve into their body tissues. This is governed by Henry's Law, which states that the amount of gas that dissolves in a liquid is directly proportional to the pressure of the gas. As a diver descends, the pressure increases, causing more gas to dissolve. If the diver ascends too quickly, the sudden decrease in pressure can cause these gases to come out of solution, forming bubbles in the body, a condition known as decompression sickness or 'the bends'. To prevent this, divers use special gas mixtures such as Nitrox, which contains less nitrogen and more oxygen than air, and follow careful ascent procedures to allow gases to safely leave their bodies.

Astronauts, on the other hand, face the opposite problem. In the vacuum of space, there is no external pressure, which can cause gases in the body and equipment to expand. This is described by Boyle's Law, which states that the volume of a gas is inversely proportional to its pressure. To manage this, astronauts' spacesuits and spacecraft are pressurised with a carefully controlled mixture of gases, typically oxygen and nitrogen, at a lower pressure than atmospheric pressure. This prevents gas expansion problems while still providing enough oxygen for breathing. Additionally, before leaving the spacecraft for a spacewalk, astronauts undergo a process called prebreathing, where they breathe pure oxygen to remove nitrogen from their bodies, preventing decompression sickness when they move to the lower pressure in their spacesuits.

In both cases, understanding and managing gas behaviour under different pressures is crucial for safety and survival in these extreme environments.