How long does oxygen last in the spacesuit?
The space suit, called the Extravehicular Mobility Unit or EMU, uses 100 percent oxygen instead of air. When a crewmember does a spacewalk, the suit is pressurized to about 1/3 of atmospheric pressure. The amount of oxygen contained in air at this pressure is not adequate, thus requiring the use of pure oxygen. Each EMU has two oxygen tanks (similar to scuba diving tanks) that work with a carbon dioxide removal system to allow a 6 to 8.5 hour spacewalk. Without the ability to remove carbon dioxide, the oxygen in the tanks would run out more quickly, because much would be tied up in exhaled gas. The amount of oxygen consumed, and carbon dioxide produced by a crewmember is dependent on his/her metabolic rate. The life support system holds other things that get consumed during a spacewalk as well. These include a battery and cooling water. These too allow a 6 to 8.5 hour spacewalk.
