Editing Controlled ecological life-support system

{{Short description|Technology on Space Stations & Closed Ecosystems}}
{{more footnotes|date=September 2010}}
'''Controlled''' (or '''closed''') '''ecological life-support systems''' (acronym '''CELSS''') are a self-supporting [[life support system]] for [[space stations]] and colonies typically through controlled [[closed ecological system]]s, such as the [[BioHome]], [[BIOS-3]], [[Biosphere 2]], [[Mars Desert Research Station]], and [[Yuegong-1]].

==Original concept==
CELSS was first pioneered by the [[Soviet Union]] during the famed "[[Space Race]]" in the 1950s–60s. Originated by [[Konstantin Tsiolkovsky]] and furthered by [[Vladimir Vernadsky|V.I. Vernadsky]], the first forays into this science were the use of closed, unmanned ecosystems, expanding into the research facility known as the [[BIOS-3]].

Then in 1965, manned experiments began in the [[BIOS-3]].

==Rationale==
[[Human presence in space]], thus far, has been limited to our own [[Earth]]–[[Moon]] system. Also, everything that [[astronauts]] would need in the way of life support ([[air]], [[water]], and [[food]]) has been brought with them. This may be economical for short missions of [[spacecraft]], but it is not the most viable solution when dealing with the life support systems of a long-term craft (such as a [[generation ship]]) or a settlement.

The aim of CELSS is to create a regenerative environment that can support and maintain [[human]] life via [[agricultural]] means.

==Components of CELSS==

===Air revitalization===
In non-CELSS environments, air replenishment and {{CO2|link=yes}} processing typically consists of stored [[Oxygen tank|air tank]]s and [[Carbon dioxide scrubber|{{CO2}} scrubbers]]. The drawback to this method lies in the fact that upon depletion the tanks would have to be refilled; the scrubbers would also require replacement after they become ineffective.

There is also the issue of processing [[Outgassing|toxic fumes]], which come from the [[Chemical synthesis|synthetic]] materials used in the construction of habitats. Therefore, the issue of how [[air quality]] is maintained requires attention; in experiments, it was found that the plants also removed [[volatile organic compounds]] [[offgassed]] by synthetic materials used thus far to build and maintain all man-made habitats.

In CELSS, air is initially supplied by external supply, but is maintained by the use of [[foliage]] plants, which create [[oxygen]] in [[photosynthesis]] (aided by the waste-byproduct of human [[Respiration (physiology)|respiration]], {{CO2}}). Eventually, the main goal of a CELSS environment is to have foliage plants take over the complete and total production of oxygen needs; this would make the system a ''closed'', instead of ''controlled'', system.

===Food / consumables production===
As with all present forays into space, crews have had to store all [[consumables]] they require prior to launch. Typically, hard-food consumables were [[freeze dried]] so that the craft's weight could be reduced.

Of course, in a self-sustaining ecosystem, a place for crops to grow would be set aside, allowing foods to be grown and cultivated. The larger the group of people, the more crops would have to be grown.

As for water, experiments have shown that it would be derived from [[Condensation|condensate]] in the air (a byproduct of [[air conditioning]] and vapors), as well as excess moisture from plants. It would then have to be filtered by some means, either by nature or by machine.{{Citation needed|date=November 2009}}

=== Waste-water treatment===
Early space-flight had travelers either ejecting their wastes into space or storing it for a return trip.

CELSS studied means of breaking down [[human waste]]s and, if possible, integrating the processed products back into the ecology. For instance, [[urine]] was processed into water, which was safe for use in [[toilet]]s and watering plants.

Wastewater treatment makes use of plants, particularly aquatic, to process the wastewater. It has been shown that the more waste is treated by the [[aquatic plant]]s (or, more specifically, their [[root system]]s), the larger the aquatic plants grow.

In tests, such as those done in the [[BioHome]], the plants also made viable [[compost]] as a [[growth medium]] for crops.

==Closed versus controlled==
Closed systems are totally self-reliant, recycling everything indefinitely with no external interaction. The life of such a system is limited, as the [[entropy]] of a closed system can only [[Second law of thermodynamics|increase with time]]. But if the otherwise closed system is allowed to accept high-temperature [[radiant energy]] from an external source (e.g., sunlight) and to reject low-temperature waste heat to deep space, it can continue indefinitely. An example of such a system is the [[Earth]] itself.

Controlled systems, by contrast, depend on certain external interactions such as periodic [[Maintenance, repair and operations|maintenance]]. An example of such a system is the [[ISS]].

==Notable CELSS projects==
{{category see also|Controlled ecological life support systems}}

* [[BioHome]]
* [[Biosphere 2]]
* [[BIOS-3]]
* Biosphere J<ref>[http://www.ecotechnics.edu/1996.html Biosphere J] {{webarchive|url=https://web.archive.org/web/20060912163253/http://www.ecotechnics.edu/1996.html |date=2006-09-12 }}</ref>
* Controlled Environment Systems Research Facility<ref>[http://www.ces.uoguelph.ca Controlled Environment Systems Research Facility], University of Guelph</ref>
* [[Biotron (disambiguation)]]
* [[Biotron (Western University)|Biotron Experimental Climate Change Research Facility]]<ref>[http://www.biotron.uwo.ca Biotron Experimental Climate Change Research Facility], University of Western Ontario</ref>
* [https://docs.lib.purdue.edu/alsnscort/ ALS-NSCORT] - Advanced Life Support - NASA Specialized Center of Research and Training

==Other types of regenerative ecological systems==
*[[Bioregenerative life support system]] (acronym: BLSS)
*[[Environmental Control and Life Support System]] ([[acronym]] ECLSS)
*[[Engineered Closed/Controlled EcoSystem]] ([[acronym]] ECCES)
*[[Spome]]

==See also==
* [[Life support system]]
* [[Closed ecological system]]
* [[Arcology]]

==References==
{{Reflist}}
* {{cite web
 | last = Borthwick
 | first = Lindsey
 | year = 2008
 | url = http://www.onearth.org/article/biologists-dig-deeper
 | title = OnEarth Magazine » Biologists Dig Deeper
 }}
* {{cite web
 | last = Prado
 | first = Mark
 | year = 2002
 | url = http://www.permanent.com/s-celss.htm
 | title = Ecological Issues and CELSS
 | work = PERMANENT Project
 | accessdate = April 19, 2006
 }}
* {{cite web
 | last = Prado
 | first = Mark
 | year = 2002
 | url = http://www.permanent.com/s-bios3.htm
 | title = Russian CELSS Studies
 | work = PERMANENT Project
 | accessdate = April 19, 2006
 }}
* {{cite web
 | last = Fitch
 | first = Cris
 | year = 2003
 | url = http://www.orbit6.com:80/celss/celss.htm
 | title = Biospheres, Controlled Ecosystems, and Life Support Systems
 | work = Orbit 6
 | archive-url = https://web.archive.org/web/20061021195859/http://www.orbit6.com:80/celss/celss.htm
 | accessdate = April 19, 2006
 | archive-date = 2006-10-21
 }}
* {{cite web
 |url         = http://library.thinkquest.org/12145/lifes3.htm
 |title       = Functions of a CELSS
 |work        = Mars Academy
 |accessdate  = April 19, 2006
 |url-status     = dead
 |archiveurl  = https://web.archive.org/web/20061107170038/http://library.thinkquest.org/12145/lifes3.htm
 |archivedate = November 7, 2006
}}

{{Authority control}}

[[Category:Controlled ecological life support systems| ]]
[[Category:Ecological experiments]]
[[Category:Systems ecology]]
[[Category:Spacecraft life support systems]]