Imagine yourself in space- one of the most hostile environments for man to survive in. There is no air to breathe. Temperatures are extreme - 120 degrees centigrade in sunlight and a minus 100 otherwise. There is no atmosphere to protect you from the harmful rays of the sun. There is dust, and along with it, particles, small and big (micrometeorides) moving at high speed around you. As there is no atmosphere, the pressure around you is almost zero, which means your blood vessels will rupture from the pressure from with in, the pressure exerted by the fluids in our body is equal to the atmospheric pressure on ground. There is no gravity to keep you down. What you wear is what is going to keep you alive in this environment.
Designed to simulate earth conditions, and prevent the hazards of space, a spacesuit is actually a mini-earth. Indeed, an astronaut takes an earth-like environment with him to survive in space.
A spacesuit is like an inflated balloon cushioning the entire body with atmospheric pressure, just like it is on earth. It provides pure oxygen for breathing and an arrangement to remove carbon dioxide that the astronaut breathes out.
The spacesuit also shields the astronaut from other hazards. To cope with the extremes of temperature, most spacesuits are heavily insulated with layers of fabric. This also protects the body from speeding meteorites and dust. A helmet works like sunglasses allowing only a small desired portion of the sunlight to penetrate through. The outer layers of the suit are designed to reflect the sun light to prevent it from reaching the astronaut’s body.
On earth, we would sweat it out, the sweat would evaporate, to cool us down. This can’t happen in space. Thus, water –cooled garments remove the body’s heat produced due to strenuous activity.
Equipped with radio transmitters and receivers in a backpack, and headsets with microphones and earphones, space walking astronauts can talk with ground controllers and other astronauts.
Without gravity, it is difficult to move around. If you push on something, you fly off in the opposite direction. Spacecrafts are equipped with footholds and hand restraints to help astronauts work in micro gravity. An inflated spacesuit in water simulates micro gravity. Just before a space mission, astronauts thus practice space walking in big water tanks.