ISS ECLSS
The International Space Station (ISS) Environmental Control and Life Support System (ECLSS) is a life support system that provides or controls atmospheric pressure, fire detection and suppression, oxygen levels, proper ventilation, waste management and water supply.
It was jointly designed and tested by NASA's Marshall Space Flight Center, UTC Aerospace Systems, Boeing, Lockheed Martin, and Honeywell.
[1] The system has three primary functions: Water Recovery, Air Revitalization, and Oxygen Generation, the purpose of which is to ensure safe and comfortable environments for personnel aboard the ISS.
The Water Recovery System was installed initially in Destiny on a temporary basis in November 2008[2] and moved into Tranquility (Node 3) in February 2010.
[4] The Urine Processor Assembly uses a low pressure vacuum distillation process that uses a centrifuge to compensate for the lack of gravity and thus aid in separating liquids and gasses.
[2] Although the design called for recovery of 85% of the water content, subsequent experience with calcium sulfate precipitation[3] (in the free-fall conditions present on the ISS, calcium levels in urine are elevated due to bone density loss) has led to a revised operational level of recovering 70% of the water content.
Other by-products of human metabolism, such as methane from flatulence and ammonia from sweat, are removed by activated charcoal filters or by the Trace Contaminant Control System (TCCS).
This is a NASA rack, placed in Tranquility, designed to provide a Carbon Dioxide Removal Assembly (CDRA), a Trace Contaminant Control Subassembly (TCCS) to remove hazardous trace contamination from the atmosphere and a Major Constituent Analyser (MCA) to monitor nitrogen, oxygen, carbon dioxide, methane, hydrogen, and water vapour.
Prior to the activation of the Sabatier System in October 2010, hydrogen and carbon dioxide extracted from the cabin was vented overboard.
[13] The Advanced Closed Loop System (ACLS) is an ESA rack that converts carbon dioxide (CO2) and water into oxygen and methane.
[14] The ACLS was delivered on the Kounotori 7 launch in September 2018 and installed in the Destiny module as a technology demonstrator (planned to operate for one to two years).
The three Elektron units on the ISS have been plagued with problems, frequently forcing the crew to use backup sources (either bottled oxygen or the Vika system discussed below).
[18] In 2005, ISS personnel tapped into the oxygen supply of the recently arrived Progress resupply spacecraft when the Elektron unit failed.
A leak of corrosive, odorless potassium hydroxide forced the ISS crew to don gloves and face masks.
The incident occurred shortly after STS-115 left and just before arrival of a resupply mission (including space tourist Anousheh Ansari).
[20] The Elektron did not come back online until November 2006, after new valves and cables arrived on the October 2006 Progress resupply vessel.
