Carbon Dioxide Scrubbers - Revision history

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2019-09-14T00:46:39Z

References

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	[[Category:~~Mars Human Settlement]]~~		[[Category:Air]]
	~~[[Category:Mars Life Support Systems~~]]

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	~~<references />~~		[[Category:Mars Human Settlement]]
			[[Category:Mars Life Support Systems]]

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	[[File:Apollo13Scrubber.jpg\|thumb\|right\|The crew of Apollo 13 famously ~~had to improvise~~ an adapter for their CO<sub>2</sub> scrubber in order to avoid a deadly build-up of the toxic gas.]]A steady supply of [[oxygen]] alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is [[carbon dioxide]] (CO<sub>2</sub>), a toxic gas which, depending on the extent of its concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a [[Habitat\|Mars habitat]], this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based air recycling is a theoretical possibility which has been tested in some experimental settings.		[[File:Apollo13Scrubber.jpg\|thumb\|right\|The crew of Apollo 13 famously improvised an adapter for their CO<sub>2</sub> scrubber in order to avoid a deadly build-up of the toxic gas.]]A steady supply of [[oxygen]] alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is [[carbon dioxide]] (CO<sub>2</sub>), a toxic gas which, depending on the extent of its concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a [[Habitat\|Mars habitat]], this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based air recycling is a theoretical possibility which has been tested in some experimental settings.

	==Dangers of Excessive CO<sub>2</sub> Concentration==		==Dangers of Excessive CO<sub>2</sub> Concentration==
	A human being exhales approximately one kilogram of CO<sub>2</sub> per day.<ref name=":1">James, J. T., & Macatangay, A. (2009). ''Carbon Dioxide – Our Common “Enemy.”'' 8.</ref> The concentration of this gas aboard the [[International Space Station]] averages about 0.4%, ten times that of Earth's atmosphere.<ref name=":8" /> At these levels, side effects vary from person to person, with some astronauts unaffected and others experiencing headaches and irritability. At higher levels, however, CO<sub>2</sub> can quickly become toxic:		A human being exhales approximately one kilogram of CO<sub>2</sub> per day.<ref name=":1">James, J. T., & Macatangay, A. (2009). ''Carbon Dioxide – Our Common “Enemy.”'' 8.</ref> The concentration of this gas aboard the [[International Space Station]] averages about 0.4%, ten times that of Earth's atmosphere.<ref name=":8" /> At these levels, side effects vary from person to person, with some astronauts unaffected and others experiencing headaches and irritability. At higher levels, however, CO<sub>2</sub> can quickly become toxic:
	{\| class="wikitable"		{\| class="wikitable"
	\|+Symptoms Experienced According to CO<sub>2</sub> Level<ref name=":0">Freudenrich, C. (2011). How is carbon dioxide eliminated aboard a spacecraft? \| HowStuffWorks. Retrieved August 15, 2019, from HowStuffWorks website: <nowiki>https://science.howstuffworks.com/carbon-dioxide-eliminated-aboard-spacecraft.htm</nowiki></ref>		\|+Symptoms Experienced According to CO<sub>2</sub> Level<ref name=":0">Freudenrich, C. (2011). How is carbon dioxide eliminated aboard a spacecraft? \| HowStuffWorks. Retrieved August 15, 2019, from HowStuffWorks website: <nowiki>https://science.howstuffworks.com/carbon-dioxide-eliminated-aboard-spacecraft.htm</nowiki></ref>
	!CO<sub>2</sub> Concentration		!CO<sub>2</sub> Concentration
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	==See also==		==See also==

	*[[Life support]]		*[[Life support]]
	*[[In-situ resource utilization]]		*[[In-situ resource utilization]]

	==References==		==References==

	*		*
	<references />		<references />

Sdubois at 18:04, 19 August 2019

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Sdubois: /* Dangers of Excessive CO2 Concentration */

2019-08-19T16:34:31Z

Dangers of Excessive CO2 Concentration

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Sdubois at 15:18, 19 August 2019

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	[[File:Apollo13Scrubber.jpg\|thumb\|right\|The crew of Apollo 13 famously had to improvise an adapter for their CO<sub>2</sub> scrubber in order to avoid a deadly build-up of the toxic gas.]]A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which, depending on the ~~relative level~~ of concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a Mars habitat, this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based ~~CO<sub>2</sub> scrubbing~~ is a theoretical possibility which has been tested in some experimental settings.		[[File:Apollo13Scrubber.jpg\|thumb\|right\|The crew of Apollo 13 famously had to improvise an adapter for their CO<sub>2</sub> scrubber in order to avoid a deadly build-up of the toxic gas.]]A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which, depending on the extent of its concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a Mars habitat, this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based air recycling is a theoretical possibility which has been tested in some experimental settings.

	==Dangers of Excessive CO<sub>2</sub> Concentration==		==Dangers of Excessive CO<sub>2</sub> Concentration==
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	NASA has set strict limits of acceptable CO<sub>2</sub> concentration on spacecraft. The longer the duration of the flight, the lower the permissible maximum: for example, while allowing a maximum of 2% for a one-hour period, NASA recommends that the concentration not exceed 0.5% over a 1000-day stay<ref name=":1" /> (an as-yet hypothetical duration, as the record for longest consecutive stay in space at the time of writing is held by Russian cosmonaut Valery Polyakov at 438 days<ref>Wall, M. (2019). Most Extreme Human Spaceflight Records of All Time \| Space. Retrieved August 15, 2019, from Soace.com website: <nowiki>https://www.space.com/11337-human-spaceflight-records-50th-anniversary.html</nowiki></ref>). The proportionate decrease in concentration acceptability in accordance with duration accounts for the fact that the longer the period of time, the higher the likelihood of CO<sub>2</sub>-induced behavioral changes negatively affecting missions requiring close personal contact in confined spaces.		NASA has set strict limits of acceptable CO<sub>2</sub> concentration on spacecraft. The longer the duration of the flight, the lower the permissible maximum: for example, while allowing a maximum of 2% for a one-hour period, NASA recommends that the concentration not exceed 0.5% over a 1000-day stay<ref name=":1" /> (an as-yet hypothetical duration, as the record for longest consecutive stay in space at the time of writing is held by Russian cosmonaut Valery Polyakov at 438 days<ref>Wall, M. (2019). Most Extreme Human Spaceflight Records of All Time \| Space. Retrieved August 15, 2019, from Soace.com website: <nowiki>https://www.space.com/11337-human-spaceflight-records-50th-anniversary.html</nowiki></ref>). The proportionate decrease in concentration acceptability in accordance with duration accounts for the fact that the longer the period of time, the higher the likelihood of CO<sub>2</sub>-induced behavioral changes negatively affecting missions requiring close personal contact in confined spaces.

	Moderating CO<sub>2</sub> levels over such a long period of time naturally implies weight and power demands, yet NASA has adopted more stringent regulations than the Navy, which allows up to 2.5% concentrations for submarine personnel over a 24-hour period.<ref name=":1" /> While both types of crews operate in a confined area with an artificially-regulated atmosphere, repairing a CO<sub>2</sub> removal system in space constitutes a potentially more complex task where one cannot simply surface in the event of an unsuccessful attempt brought on by concentration difficulties. Hypothetically, a well-developed Mars colony could relax such limitations slightly once it is large enough to contain multiple fail-safes and back-ups, thereby reducing the energy demands on the colony as a whole.		Moderating CO<sub>2</sub> levels over such a long period of time naturally implies weight and power demands, yet NASA has adopted more stringent regulations than the Navy, which allows up to 2.5% concentrations for submarine personnel over a 24-hour period.<ref name=":1" /> While both types of crews operate in a confined area with an artificially-regulated atmosphere, repairing a CO<sub>2</sub> removal system in space constitutes a potentially more complex task where one cannot simply surface in the event of an unsuccessful attempt brought on by concentration difficulties. Hypothetically, a well-developed Mars colony could relax such limitations slightly once it is large enough to contain multiple fail-safes and back-ups, thereby reducing the energy demands on the colony as a whole. Even so, the discomfort caused by extended exposure to these levels means that maintaining concentrations at near-Earth levels will likely remain a high priority.

	In the days of interplanetary travel before colonists establish a self-sustaining colony, missions could screen crews for CO<sub>2</sub>-resistant individuals.<ref name=":8" /> As mentioned above, the effects of elevated CO<sub>2</sub> concentrations aboard the ISS have affected astronauts to differing degrees—because higher permissible levels of CO<sub>2</sub> mean less demand on scrubbing systems, ensuring crews consist only of members whose performance remains unchanged in the presence of increased concentrations could provide an easy way to reduce mission overhead.		In the days of interplanetary travel before colonists establish a self-sustaining colony, missions could screen crews for CO<sub>2</sub>-resistant individuals.<ref name=":8" /> As mentioned above, the effects of elevated CO<sub>2</sub> concentrations aboard the ISS have affected astronauts to differing degrees—because higher permissible levels of CO<sub>2</sub> mean less demand on scrubbing systems, ensuring crews consist only of members whose performance remains unchanged in the presence of increased concentrations could provide an easy way to reduce mission overhead.

Sdubois at 22:52, 18 August 2019

2019-08-18T22:52:25Z

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	A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which, depending on the relative level of concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a Mars habitat, this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based CO<sub>2</sub> scrubbing is a theoretical possibility which has been tested in some experimental settings.		[[File:Apollo13Scrubber.jpg\|thumb\|right\|The crew of Apollo 13 famously had to improvise an adapter for their CO<sub>2</sub> scrubber in order to avoid a deadly build-up of the toxic gas.]]A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which, depending on the relative level of concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a Mars habitat, this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based CO<sub>2</sub> scrubbing is a theoretical possibility which has been tested in some experimental settings.

	==Dangers of Excessive CO<sub>2</sub> Concentration==		==Dangers of Excessive CO<sub>2</sub> Concentration==

Sdubois: /* Dangers of Excessive CO2 Concentration */

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Dangers of Excessive CO2 Concentration

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	A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which can cause symptoms varying from mild discomfort to death ~~depending on the relative level of concentration~~. In the sealed environment of a spacecraft or a Mars habitat, this gas must be removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based CO<sub>2</sub> scrubbing is a theoretical possibility which has been tested in some experimental settings.		A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which, depending on the relative level of concentration, can cause symptoms varying from mild discomfort to death. In the sealed environment of a spacecraft or a Mars habitat, this gas must be carefully monitored and removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based CO<sub>2</sub> scrubbing is a theoretical possibility which has been tested in some experimental settings.

	==Dangers of Excessive CO<sub>2</sub> Concentration==		==Dangers of Excessive CO<sub>2</sub> Concentration==

Sdubois: /* Dangers of Excessive CO2 Concentration */

2019-08-18T22:37:26Z

Dangers of Excessive CO2 Concentration

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	~~[This~~ is ~~an article~~ in ~~progress~~, ~~and~~ is ~~currently being written]~~		A steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is carbon dioxide (CO<sub>2</sub>), a toxic gas which can cause symptoms varying from mild discomfort to death depending on the relative level of concentration. In the sealed environment of a spacecraft or a Mars habitat, this gas must be removed from the air in a process called CO<sub>2</sub> scrubbing. Spacecraft have until now used a variety of artificial means to accomplish this, although plant-based CO<sub>2</sub> scrubbing is a theoretical possibility which has been tested in some experimental settings.

	==Dangers of Excessive CO<sub>2</sub> Concentration==		==Dangers of Excessive CO<sub>2</sub> Concentration==
	A ~~steady supply of oxygen alone is insufficient to keep astronauts breathing. While the intake of oxygen is essential for respiration, the by-product of this respiration is the exhalation of~~ approximately one kilogram of ~~carbon-dioxide~~ per day.<ref name=":1">James, J. T., & Macatangay, A. (2009). ''Carbon Dioxide – Our Common “Enemy.”'' 8.</ref> The concentration of this gas aboard the International Space Station averages about 0.4%, ten times that of Earth's atmosphere.<ref name=":8" /> At these levels, side effects vary from person to person, with some astronauts unaffected and others experiencing headaches and irritability. At higher levels, however, CO<sub>2</sub> can quickly become toxic:		A human being exhales approximately one kilogram of CO<sub>2</sub> per day.<ref name=":1">James, J. T., & Macatangay, A. (2009). ''Carbon Dioxide – Our Common “Enemy.”'' 8.</ref> The concentration of this gas aboard the International Space Station averages about 0.4%, ten times that of Earth's atmosphere.<ref name=":8" /> At these levels, side effects vary from person to person, with some astronauts unaffected and others experiencing headaches and irritability. At higher levels, however, CO<sub>2</sub> can quickly become toxic:
	{\| class="wikitable"		{\| class="wikitable"
	\|+Symptoms Experienced According to CO<sub>2</sub> Level<ref name=":0">Freudenrich, C. (2011). How is carbon dioxide eliminated aboard a spacecraft? \| HowStuffWorks. Retrieved August 15, 2019, from HowStuffWorks website: <nowiki>https://science.howstuffworks.com/carbon-dioxide-eliminated-aboard-spacecraft.htm</nowiki></ref>		\|+Symptoms Experienced According to CO<sub>2</sub> Level<ref name=":0">Freudenrich, C. (2011). How is carbon dioxide eliminated aboard a spacecraft? \| HowStuffWorks. Retrieved August 15, 2019, from HowStuffWorks website: <nowiki>https://science.howstuffworks.com/carbon-dioxide-eliminated-aboard-spacecraft.htm</nowiki></ref>

Sdubois: /* Other CO2 Considerations in Microgravity Environment */

2019-08-18T22:30:15Z

Other CO2 Considerations in Microgravity Environment

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	Given the mass requirements of a plant-based system, such methods are perhaps better suited to future habitats on Mars. In-situ resource utilization techniques will allow colonists to avoid shipping large quantities of water, soil, or oxygen, all of which can be obtained on site.<ref name=":3" /> Hydroponic and aeroponic systems provide alternatives to any complications posed by the use of Mars regolith in a soil-based system, although this soil does contain all the nutrients necessary for plant survival once existing perchlorates are removed.<ref>Jordan, G. (2015, October 5). Can Plants Grow with Mars Soil? [Text]. Retrieved August 16, 2019, from NASA website: <nowiki>http://www.nasa.gov/feature/can-plants-grow-with-mars-soil</nowiki></ref>		Given the mass requirements of a plant-based system, such methods are perhaps better suited to future habitats on Mars. In-situ resource utilization techniques will allow colonists to avoid shipping large quantities of water, soil, or oxygen, all of which can be obtained on site.<ref name=":3" /> Hydroponic and aeroponic systems provide alternatives to any complications posed by the use of Mars regolith in a soil-based system, although this soil does contain all the nutrients necessary for plant survival once existing perchlorates are removed.<ref>Jordan, G. (2015, October 5). Can Plants Grow with Mars Soil? [Text]. Retrieved August 16, 2019, from NASA website: <nowiki>http://www.nasa.gov/feature/can-plants-grow-with-mars-soil</nowiki></ref>

	==~~Other~~ CO<sub>2</sub> ~~Considerations~~ in ~~Microgravity Environment=~~=		==Airflow Complications in Microgravity Environment==
			Regardless of whether artificial or biological systems provide the means for CO<sub>2</sub> scrubbing aboard a spacecraft, managing CO<sub>2</sub> concentrations in space presents several unique challenges.<ref name=":6" /> On Earth, gases flow and settle according to density differences, but this does not occur in microgravity. Special ventiliation equipment is required to ensure the CO<sub>2</sub> reaches appropriate intake areas, even if those intakes are biological in nature. Similarly, freshly scrubbed air must be distributed about the craft. These ventilation systems naturally require a certain degree of maintenance to avoid performance degradation due to the accumulation of dust or other debris.

			Similarly, crew members are rarely distributed about the spacecraft in a uniform fashion, meaning that pockets of higher CO<sub>2</sub> concentrations will develop where several crew members are working together, or when one is sleeping in the same space for several hours at a time. Furthermore, the volumetric characteristics of a transport spacecraft will regularly vary depending on the number of crew members, the shape and stowage position of cargo, the movement of that cargo obstructing airflow through passages, etc. All of these factors must be accounted for when installing and maintaining ventilation hardware.

	==References==		==References==