Atmospheric loss - Revision history

RichardWSmith: Fixed link.

2025-08-03T14:38:16Z

Fixed link.

RichardWSmith: Added link.

2025-08-03T14:37:24Z

Added link.

RichardWSmith: /* Gasses Absorbed Into Crust */

2025-07-31T16:38:27Z

Gasses Absorbed Into Crust

RichardWSmith: /* Gasses Absorbed Into Crust */ Corrected error.

2025-07-31T16:36:25Z

Gasses Absorbed Into Crust: Corrected error.

RichardWSmith: /* Gasses Absorbed Into Crust */ Added adsorption.

2025-07-31T16:33:00Z

Gasses Absorbed Into Crust: Added adsorption.

RichardWSmith: /* Gasses Lost To Space By Solar Wind Sputtering */ Added link.

2025-07-29T18:14:36Z

Gasses Lost To Space By Solar Wind Sputtering: Added link.

RichardWSmith: /* Gasses Lost To Space By Solar Wind Sputtering */ Effects of sputtering may be overstated? reference.

2025-07-29T17:21:17Z

Gasses Lost To Space By Solar Wind Sputtering: Effects of sputtering may be overstated? reference.

RichardWSmith: /* Gasses Absorbed Into Crust */ Added siderite.

2025-07-26T16:26:45Z

Gasses Absorbed Into Crust: Added siderite.

RichardWSmith: /* Protection From Solar Wind Sputtering */

2025-07-20T20:59:33Z

Protection From Solar Wind Sputtering

RichardWSmith: /* Bibliography */ Improve formatting.

2025-07-20T02:21:18Z

Bibliography: Improve formatting.

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 It is clear that Mars had a thicker [[atmosphere]] in the past, perhaps 3 to 4 bar.  It is a near vacuum now (0.6 bar), so what has happened to Mars' atmosphere?
-See also: [[Early Atmosphere]].
+See also: [[Ancient Atmosphere]].
 ==Gasses Absorbed Into Crust==

← Older revision		Revision as of 14:37, 3 August 2025
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	It is clear that Mars had a thicker [[atmosphere]] in the past, perhaps 3 to 4 bar. It is a near vacuum now (0.6 bar), so what has happened to Mars' atmosphere?		It is clear that Mars had a thicker [[atmosphere]] in the past, perhaps 3 to 4 bar. It is a near vacuum now (0.6 bar), so what has happened to Mars' atmosphere?
		+
		+	See also: [[Early Atmosphere]].

	==Gasses Absorbed Into Crust==		==Gasses Absorbed Into Crust==

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 -- Cold clays can absorb carbon dioxide.  This study <ref>https://www.science.org/doi/10.1126/sciadv.adm8443</ref> suggests that 0.6 to 1.3 bar of CO<sub>2</sub> (or methane) could be held in clays.  If the planet warms, this CO2 would gradually out gas.  (The same study suggests that Mars' early atmosphere could not have been thicker than 4 bar.)
--- At cold temperatures, gases can attach themselves to the pores of rocks and dust particles.  This is known as 'adsorption'.  When the temperature warms, they will outgas (desorbed).  Potentially, 0.07 Bar (?) of CO<sub>2</sub> is adsorbed into the top 100 meters of the crust, tho it would take thousands of years for this full amount to outgas if Mars was warmed.  (The 0.07 Bar is speculative, but there would certainly be some pressure increase.)
+-- At cold temperatures, gases can attach themselves to the pores of rocks and dust particles.  This is known as 'adsorption'.  When the temperature warms, they will outgas (desorbed).  Potentially, 0.006 Bar (?) of CO<sub>2</sub> is adsorbed into the top 100 meters of the crust, tho it would take thousands of years for this full amount to outgas if Mars was warmed.  (The 0.006 Bar is speculative, but there would certainly be some pressure increase.)
 -- A recent paper has shown that a huge amount of water has been absorbed by rocks.  On Earth, plate Tectonics takes these hydrated minerals and melts them, where water can return to the surface via vulcanism. On Mars the water remains in these minerals. <ref>https://science.sciencemag.org/content/early/2021/03/15/science.abc7717 - Long term drying of Mars by sequestration of Ocean-scale volumes of water in the crust</ref>

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 -- Carbon dioxide has been spotted as ice at the Martian poles (especially the South Pole which gets colder than the North Pole).  See [[Periareion]].  The South Pole has buried CO2 which does not sublimate each year.  <ref>https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2022JE007193</ref>
--- Cold clays can absorb carbon dioxide.  This study <ref>https://www.science.org/doi/10.1126/sciadv.adm8443</ref> suggests that 1.5 bar of CO<sub>2</sub> (or methane) could be held in clays.  If the planet warms, this CO2 would gradually out gas.  (The same study suggests that Mars' early atmosphere could not have been thicker than 4 bar.)
+-- Cold clays can absorb carbon dioxide.  This study <ref>https://www.science.org/doi/10.1126/sciadv.adm8443</ref> suggests that 0.6 to 1.3 bar of CO<sub>2</sub> (or methane) could be held in clays.  If the planet warms, this CO2 would gradually out gas.  (The same study suggests that Mars' early atmosphere could not have been thicker than 4 bar.)
 -- At cold temperatures, gases can attach themselves to the pores of rocks and dust particles.  This is known as 'adsorption'.  When the temperature warms, they will outgas (desorbed).  Potentially, 0.07 Bar (?) of CO<sub>2</sub> is adsorbed into the top 100 meters of the crust, tho it would take thousands of years for this full amount to outgas if Mars was warmed.  (The 0.07 Bar is speculative, but there would certainly be some pressure increase.)

← Older revision		Revision as of 16:33, 31 July 2025
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	-- Cold clays can absorb carbon dioxide. This study <ref>https://www.science.org/doi/10.1126/sciadv.adm8443</ref> suggests that 1.5 bar of CO<sub>2</sub> (or methane) could be held in clays. If the planet warms, this CO2 would gradually out gas. (The same study suggests that Mars' early atmosphere could not have been thicker than 4 bar.)		-- Cold clays can absorb carbon dioxide. This study <ref>https://www.science.org/doi/10.1126/sciadv.adm8443</ref> suggests that 1.5 bar of CO<sub>2</sub> (or methane) could be held in clays. If the planet warms, this CO2 would gradually out gas. (The same study suggests that Mars' early atmosphere could not have been thicker than 4 bar.)
		+
		+	-- At cold temperatures, gases can attach themselves to the pores of rocks and dust particles. This is known as 'adsorption'. When the temperature warms, they will outgas (desorbed). Potentially, 0.07 Bar (?) of CO<sub>2</sub> is adsorbed into the top 100 meters of the crust, tho it would take thousands of years for this full amount to outgas if Mars was warmed. (The 0.07 Bar is speculative, but there would certainly be some pressure increase.)

	-- A recent paper has shown that a huge amount of water has been absorbed by rocks. On Earth, plate Tectonics takes these hydrated minerals and melts them, where water can return to the surface via vulcanism. On Mars the water remains in these minerals. <ref>https://science.sciencemag.org/content/early/2021/03/15/science.abc7717 - Long term drying of Mars by sequestration of Ocean-scale volumes of water in the crust</ref>		-- A recent paper has shown that a huge amount of water has been absorbed by rocks. On Earth, plate Tectonics takes these hydrated minerals and melts them, where water can return to the surface via vulcanism. On Mars the water remains in these minerals. <ref>https://science.sciencemag.org/content/early/2021/03/15/science.abc7717 - Long term drying of Mars by sequestration of Ocean-scale volumes of water in the crust</ref>

← Older revision		Revision as of 18:14, 29 July 2025
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	==Gasses Lost To Space By Solar Wind Sputtering==		==Gasses Lost To Space By Solar Wind Sputtering==
		+	See [[Solar Wind Sputtering]] for main article.
		+
	It is thought that atmosphere can be lost by solar wind 'sputtering'. If a planet lacks a magnetic field (see [[Magnetosphere]]) the solar wind can ionize gases in the upper atmosphere, and drag them away from the planet. This is a very slow process, but over billions of years, a significant amount of mass can be lost. A key point is that heavier molecules (such as carbon dioxide) which would normally be held by the planet's gravity can be lost from sputtering. It has been estimated that 1/3 of Mars' carbon dioxide has been lost this way. Nitrogen likewise is heavy enough to remain within Mars' gravity. But there is virtually no N2 in Mars' atmosphere. Sputtering would not account for the loss of all of this nitrogen, which suggests a significant amount will be found in the crust.		It is thought that atmosphere can be lost by solar wind 'sputtering'. If a planet lacks a magnetic field (see [[Magnetosphere]]) the solar wind can ionize gases in the upper atmosphere, and drag them away from the planet. This is a very slow process, but over billions of years, a significant amount of mass can be lost. A key point is that heavier molecules (such as carbon dioxide) which would normally be held by the planet's gravity can be lost from sputtering. It has been estimated that 1/3 of Mars' carbon dioxide has been lost this way. Nitrogen likewise is heavy enough to remain within Mars' gravity. But there is virtually no N2 in Mars' atmosphere. Sputtering would not account for the loss of all of this nitrogen, which suggests a significant amount will be found in the crust.

← Older revision		Revision as of 17:21, 29 July 2025
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	Venus lacks a magnetic field, and experiences a solar wind more than 4.4 times greater than Mars', but it still has an atmosphere over 90 bar. Why Venus has lost so little atmosphere to sputtering is an open question.		Venus lacks a magnetic field, and experiences a solar wind more than 4.4 times greater than Mars', but it still has an atmosphere over 90 bar. Why Venus has lost so little atmosphere to sputtering is an open question.
		+
		+	This recent review paper suggests that the need of a magnetic field to preserve atmospheres has been over estimated.<ref>https://arxiv.org/pdf/2003.03231</ref>

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 -- Small amounts of nitrates can be formed by Extreme [[Ultraviolet| UltraViolet Light]] (EUV) breaking up [[Nitrogen]] in the air, which combines with trace amounts of oxygen. See [[Photochemistry]].
--- Volcanic rocks eroding in a carbon dioxide rich atmosphere can form carbonates.  These have been found in surprisingly small quantities on Mars.  (It is now thought that the Martian water was acidic, which would lead to more sulphates being formed.)
+-- Volcanic rocks eroding in a carbon dioxide rich atmosphere can form carbonates.  These have been found in surprisingly small quantities on Mars.  (It is now thought that the Martian water was acidic, which would lead to more sulphates being formed.)  Recently, siderite (FeCO<sub>3</sub>) has been found in Gale crater, which if common, might explain an important CO<sub>2</sub> sink.<ref>https://www.jpl.nasa.gov/news/nasas-curiosity-rover-may-have-solved-mars-missing-carbonate-mystery/</ref>
 -- Ice has been found in Martian soil as permafrost, as ice caps at the poles, and as frosts.

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 Weak levels of paleomagnatism in areas of Mars' crust have been shown to reduce sputtering above these areas.  This suggests that humans could build an artificial magnetosphere to slow this loss.
-If we were to terraform Mars, this sputtering could be reduced by creating a superconducting ring around the planet's equator to make an artificial magnetosphere.  Alternately a powerful magnet could be put at the SOL - Mars L1 point.  (But the solar wind would push this magnet out of orbit so a significant mass would need to be spent station keeping.)  Rather than doing either of these, it may be easier to just replenish Mars' atmosphere with an occasional icy asteroid from the Kuiper Belt.
+If we were to terraform Mars, this sputtering could be reduced by creating a superconducting ring around the planet's equator to make an artificial magnetosphere.  Alternately a powerful magnet could be put at the SOL - Mars L1 point.  (But the solar wind would push this magnet out of orbit so a significant mass would need to be spent every month on station keeping.)  Rather than doing either of these, it may be easier to just replenish Mars' atmosphere with an occasional icy asteroid from the Kuiper Belt.
 A study by Marcus DuPont & Jeremiah W. Murphy published on 2021, April 08, in International Journal of Astrobiology, looked at if it would be better to build a magnet at the Sol-Mars L1 point, or make a loop around the planet.  They found that the equatorial magnetic loop was more practical. <ref>https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/fundamental-physical-and-resource-requirements-for-a-martian-magnetic-shield/600798772F8D2C2898A8F3D4058204A6 - Fundamental physics make long thin loops better than small tight ones. </ref>
 This study gave the following bits of advice: To protect the Martian atmosphere a magnetic field of 1.25 microTeslas should be created.  Counter intuitively, the mass needed to build big magnets is less than that needed to build smaller magnets (with much, much higher fields), so building a planet wide loop is cheaper than a tiny magnet at the L1 point.  A magnet around Mars' equator should be a ribbon about 5 cm wide and with a total mass of about 5x10^15 kg (~5,000,000,000,000 tonnes).  It would take ~1 Megawatt to keep it cooled to superconducting temperatures (minor compared to the cost of maintaining the current to fight the solar wind).  The equipment would not fit on a spacecraft, it would have to be built out of local material.  The cost would be astronomical with today's substances, hopefully improvements to superconductors (or carbon nano-tube superconductors) would lower the cost per square centimetre.  Building up Mars' atmosphere from natural outgassing is too slow, importing volatiles or somehow forcing Mars' crust to release gases will be required.
 ==Faint Young Sun Paradox==

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 ==Bibliography==
 // Discussion of atmospheric loss by sputtering.
 https://science.sciencemag.org/content/355/6332/1408
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 // Discussion of how thick Mars' atmosphere used to be.  See page 101.
 // Discussion of how CO2 Clathrates could be part of Mars' subsurface ice. See page 199.
 "Mars: A Warmer Wetter Planet", by Jeffrey S. Kargel, ISBN 1-85233-568-8
 // Paleomagnetism and Sputtering.
 https://ui.adsabs.harvard.edu/abs/1998PhDT........24H/abstract
 // Introductory textbook on Planetology.
 "Moons and Planets 5th Edition" by William K. Hartman, ISBN 0-534-49393-9
 ==References:==
 <references />