The life support system includes an oxygen tank, batteries, and water for the suit's cooling system. It allows an astronaut to remain outside the shuttle for up to eight hours. The unit worn on the astronaut's back contains an oxygen tank and a circulation system which pumps oxygen into the helmet. It also recirculates air, removing carbon dioxide, adding oxygen, and eliminating water vapor - you can think of it as a portable, artificial atmosphere. The suit is made from many layers of flexible, airtight materials, such as nylon and Teflon.
Mechanical seals connect the pieces of the space suit, insuring an airtight fit.
Friday If you're an astronaut on a spacewalk and you need a little snack, or a little light to see by, or just someone to talk to, it's all in your head. Or, in your helmet to be more precise. Modern spacesuits are equipped with a drink bag and a little straw attachment. With a turn of her head, an astronaut can grab a quick drink during her spacewalk. Of course there is no air in space, which means there is no sound.