The Space Shuttle's life-support system automatically supplies air and water.
   	An atmosphere like the earth's is maintained in the crew compartment. 
Atmospheric pressure is the same as standard sca-
level conditions. 
The atmosphere consists of 7936 nitrogen and 21jt oxygen, again very close to what the astronauts left on •arth. In an emergency ( asapBa }, cabin pressure is reduced. Carbon dioxide ia a waste product and must not be allowed to build up la the cabin. Therefore, canisters filled with lithi-UB hydroxide and activated charcoal remove carbon dioxide and odors ( aanaa ) fron the cabin's air. ?ans circulate the air around the cabin and through the canisters. Carbon dioxide reacts with lithium hydroxide to produce lithium carbonate and water vapor.
Two canisters are used at a time. With. four people abroad, an individual canister lasts 24 hours. They are changed alternately, that ifl one ia changed every 12,hours. As with other chores ( otfnaaHBoCTB ), responsibility for changing the carbon dioxide
absorbers is assigned to a different member of the crew each day.
The cabin's atmosphere Is controlled from panels. There are switches to select which source of oxygen you want to use. The oxygen supply ia carried,In the fora of a super-cold (cryogenic) liquid. Each. liquid-oxygen tank has beaters which vaporize some of the super-cold liquid.
If it gets too warm or too cold, one can adjust ( peryJiBRO-BSTI, ) the cabin temperature using the CABUf TEMP SWITCH. Below
this switch are controls tor the fans that circulate air through. lithium hydroxide canisters.
Electrical power tor the Orbiter ia generated by FUEL CEUiS. Oxygen and hydrogen are chemically combined In the celle to produce electricity. There is an important by-product ( noOoiHHfl
npOflyiT ) fron this reaction-water. About 3 kilograms of water is created every hour.