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Environmental Control and Life Support System
The ECLSS consists of atmosphere and water treatment and thermal systems.
Crew Compartment Cabin Pressurization
The cabin is pressurized to 14.7 psia and maintained at an average 80-percent nitrogen and 20-percent oxygen mixture by the air revitalization system.
Cabin Air Revitalization
There are five independent air loops in the cabin.
Water Coolant Loop System
The WCLS provides thermal conditioning of the crew cabin by collecting heat at a heat exchanger and transferring it to the water coolant loops.
Active Thermal Control System
The ATCS consists of Freon interchangers, radiators and heat exchangers to control thermal conditions.
Supply and Waste Water
The supply and waste water systems provide water for the flash evaporator, crew consumption and hygiene.
Waste Collection System
The waste collection system is an integrated, multifunctional system used primarily to collect and process biological wastes from crew members in a zero-gravity environment.
Waste Water Tank
A single waste water tank receives waste water from the ARS humidity separator and the waste collection system.
Airlock Support
The airlock and airlock hatches permit EVA flight crew members to transfer from the middeck crew compartment into the payload bay in EMUs without depressurizing the orbiter crew cabin.
Extravehicular Activity Mobility Units
EMU space suits provide the necessities for life support during space walks.
Crew Altitude Protection System
The crew altitude protection system is worn by the flight crew members during launch and entry.
Radioisotope Thermoelectric Generator Cooling and Gaseous Nitrogen Purge for Payloads
A cooling and purge system is installed in Discovery and Atlantis to support those payloads with RTGs or gaseous nitrogen purging requirements.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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