Ancient Atmosphere - Revision history

RichardWSmith: /* The Faint Young Sun - Warm Mars Paradox */ Added reference.

2025-08-12T00:13:35Z

The Faint Young Sun - Warm Mars Paradox: Added reference.

RichardWSmith: Was the sun hotter?

2025-08-11T23:57:48Z

Was the sun hotter?

RichardWSmith: Cold wet mars is unlikely.

2025-08-11T23:50:46Z

Cold wet mars is unlikely.

RichardWSmith: Large impactors could temp. warm planet.

2025-08-11T23:39:13Z

Large impactors could temp. warm planet.

RichardWSmith at 22:11, 11 August 2025

2025-08-11T22:11:18Z

RichardWSmith: /* The Noachian Period */

2025-08-11T22:10:59Z

The Noachian Period

RichardWSmith: /* The Atmosphere During the Hesperian */ Adding a picture.

2025-08-11T22:09:54Z

The Atmosphere During the Hesperian: Adding a picture.

RichardWSmith: /* The Noachian Period */ Adding a picture.

2025-08-11T22:08:55Z

The Noachian Period: Adding a picture.

RichardWSmith: /* Events in the Pre-Noachian Period */

2025-08-11T21:41:07Z

Events in the Pre-Noachian Period

RichardWSmith: Added missing word. Added weasel word.

2025-08-11T01:31:48Z

Added missing word. Added weasel word.

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 Some have suggested that there was much more CO<sub>2</sub> than expected.  If there were 3 to 5 Bar of CO<sub>2</sub> at the end of the Noachian, then this would go a long way to warming the planet.  However, we come to different problem: If the partial pressure of CO<sub>2</sub> was much higher, then it is easier for the carbon dioxide to frost out or snow at the poles.  If we had 5 Bar of CO<sub>2</sub>, then it is hard to explain why it would not all freeze out and lower the CO<sub>2</sub> back down to a near zero partial pressure.
-The cool sun - warm Mars problem is currently much debated.  Some think that maybe the Sun WAS NOT cooler.  If the sun was 10% more massive than we think it was, then it would actually be warmer 4 Ga than it is now.  Then liquid water flowing on Mars (and Earth) is much easier to model.  However, studies of similar stars to our sun, which are much younger, suggest that such stars might lose 0.1% of their mass in 4.5 Ga.  So how the Sun could lose 10% is very hard to explain.
+The cool sun - warm Mars problem is currently much debated.  Some think that maybe the Sun WAS NOT cooler.  If the sun was 10% more massive than we think it was, then it would actually be warmer 4 Ga than it is now.  Then liquid water flowing on Mars (and Earth) is much easier to model.  However, studies of similar stars to our sun, which are much younger, suggest that such stars might lose 0.1% of their mass in 4.5 Ga.  So how the Sun could lose 10% is very hard to explain.<ref>https://www.space.com/14565-earth-climate-young-sun-paradox.html</ref>
 Most scientists feel that the air pressure in the Noachian was from 0.5 to 1 Bar (tho other estimates put it at 2.3 Bar), and do not have an explanation of the faint young sun paradox.

@@ Line 109: / Line 109: @@
 Some have suggested that there was much more CO<sub>2</sub> than expected.  If there were 3 to 5 Bar of CO<sub>2</sub> at the end of the Noachian, then this would go a long way to warming the planet.  However, we come to different problem: If the partial pressure of CO<sub>2</sub> was much higher, then it is easier for the carbon dioxide to frost out or snow at the poles.  If we had 5 Bar of CO<sub>2</sub>, then it is hard to explain why it would not all freeze out and lower the CO<sub>2</sub> back down to a near zero partial pressure.
-The cool sun - warm Mars problem is currently much debated.  Some think that maybe the Sun WAS NOT cooler, which is scoffed at by those who know stellar evolution.
+The cool sun - warm Mars problem is currently much debated.  Some think that maybe the Sun WAS NOT cooler.  If the sun was 10% more massive than we think it was, then it would actually be warmer 4 Ga than it is now.  Then liquid water flowing on Mars (and Earth) is much easier to model.  However, studies of similar stars to our sun, which are much younger, suggest that such stars might lose 0.1% of their mass in 4.5 Ga.  So how the Sun could lose 10% is very hard to explain.
 Most scientists feel that the air pressure in the Noachian was from 0.5 to 1 Bar (tho other estimates put it at 2.3 Bar), and do not have an explanation of the faint young sun paradox.

@@ Line 121: / Line 121: @@
 ===Transient Impact Climate Change===
 This idea is that the impact of a large sized body (~100 km in diameter or a bit larger), throws up a huge amount of dust which would warm the planet and vaporize water.  This would warm the planet for hundreds to a couple thousand years.  While such events certainly happened from time to time, this would not explain the long term water erosion features.
 ==The Atmosphere During the Hesperian==

← Older revision		Revision as of 23:39, 11 August 2025
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	If Mars had a 4 Bar atmosphere in the Noachian, the slow loss of atmosphere (speeded slightly by solar wind sputtering once the magnetosphere shut down) does not explain the low atmospheric pressure now. However, I feel that they are underestimating the amount of gas absorbed into the crust. See [[Atmospheric Loss]] for more details.		If Mars had a 4 Bar atmosphere in the Noachian, the slow loss of atmosphere (speeded slightly by solar wind sputtering once the magnetosphere shut down) does not explain the low atmospheric pressure now. However, I feel that they are underestimating the amount of gas absorbed into the crust. See [[Atmospheric Loss]] for more details.
		+
		+	===Transient Impact Climate Change===
		+	This idea is that the impact of a large sized body (~100 km in diameter or a bit larger), throws up a huge amount of dust which would warm the planet and vaporize water. This would warm the planet for hundreds to a couple thousand years. While such events certainly happened from time to time, this would not explain the long term water erosion features.

	==The Atmosphere During the Hesperian==		==The Atmosphere During the Hesperian==

← Older revision		Revision as of 22:11, 11 August 2025
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	==Mars' Formation==		==Mars' Formation==
		+	[[File:Noachian_Mars.png]]
	About 4.57 Ga, Mars accreted from the proto-planetary disk, finishing this process about 4.55 Ga. There may have been a lava ocean formed from the energy of impact and radioactive decay (especially from aluminum 26). During this time, Mars formed its core, mantle, and crust.		About 4.57 Ga, Mars accreted from the proto-planetary disk, finishing this process about 4.55 Ga. There may have been a lava ocean formed from the energy of impact and radioactive decay (especially from aluminum 26). During this time, Mars formed its core, mantle, and crust.

← Older revision		Revision as of 22:10, 11 August 2025
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	==The Noachian Period==		==The Noachian Period==
−	~~[[File:Noachian_Mars.png]]~~
	This geologic epoch is when the oldest rocks on Mars formed. Mars then was a much warmer planet with many volcanoes, and running water, with snow and rain happening over large portions of the surface. Mars likely had a northern ocean then.		This geologic epoch is when the oldest rocks on Mars formed. Mars then was a much warmer planet with many volcanoes, and running water, with snow and rain happening over large portions of the surface. Mars likely had a northern ocean then.

← Older revision		Revision as of 22:09, 11 August 2025
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	==The Atmosphere During the Hesperian==		==The Atmosphere During the Hesperian==
		+	[[File:Post_Noachian_Mars.png]]
	The Hesperian period (3.7 to 3.1 Ga) was a period of declining vulcanism, thinning atmosphere, and decreasing erosion.		The Hesperian period (3.7 to 3.1 Ga) was a period of declining vulcanism, thinning atmosphere, and decreasing erosion.

← Older revision		Revision as of 22:08, 11 August 2025
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	==The Noachian Period==		==The Noachian Period==
		+	[[File:Noachian_Mars.png]]
	This geologic epoch is when the oldest rocks on Mars formed. Mars then was a much warmer planet with many volcanoes, and running water, with snow and rain happening over large portions of the surface. Mars likely had a northern ocean then.		This geologic epoch is when the oldest rocks on Mars formed. Mars then was a much warmer planet with many volcanoes, and running water, with snow and rain happening over large portions of the surface. Mars likely had a northern ocean then.

@@ Line 39: / Line 39: @@
 Some estimates suggest that Mars lost 0.35 to 0.6 Bar of pressure from such impacts in its history.
-===Events in the Pre-Noachian Period===
+==Events in the Pre-Noachian Period==
 The pre-noachian period, ranges from 4.55 Ga until 4.1 Ga as little or no rocks remain from this period.  During this period, the crust formed, & the magnetic dynamo turns on protecting Mars' early atmosphere from [[Solar Wind Sputtering]].  Major impact basins form including the formation of the northern lowlands and southern highlands (likely from a giant northern impact).  A secondary atmosphere formed as hydrogen escaped into space and water condensed to liquid.

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 Most scientists feel that the air pressure in the Noachian was from 0.5 to 1 Bar (tho other estimates put it at 2.3 Bar), and do not have an explanation of the faint young sun paradox.
-The writer of this essay (Rick) feels that Mars must have had a thick atmosphere, of carbon dioxide and nitrogen.  Nitrogen is not a greenhouse gas, but it does have thermal inertia.  Perhaps with a thick atmosphere, winds could move enough heat from the equator to the poles, to keep the carbon dioxide from freezing out.  Scientists (Manning et al. & Soto et al) have studied this and it is hard to pin down the exact numbers, but they suggest that Mars would have to have at least 0.7 Bar of atmospheric pressure for this to be significant.  At pressures higher than this, any polar CO<sub>2</sub> would be transitory.
+The writer of this essay (Rick) feels that Mars must have had a thick atmosphere, of carbon dioxide and nitrogen.  Nitrogen is not a greenhouse gas, but it does have thermal inertia.  Perhaps with a thick atmosphere, winds could move enough heat from the equator to the poles, to keep the carbon dioxide from freezing out.  Scientists (Manning et al. & Soto et al) have studied this and it is hard to pin down the exact numbers, but they suggest that Mars would have to have at least 0.7 Bar of atmospheric pressure for this to be significant.  At pressures higher than this, any polar CO<sub>2</sub> ice would likely be transitory.
 Also, a thicker atmosphere (with plenty of N<sub>2</sub>) would support more airborne dust, which would darken ice and frost.  Dust in the air, warms the atmosphere by slowing radiation loss, and absorbing sunlight and reemitting the energy as heat.  (Altho if Mars had common rain and snow, it would have much less dust in the air.)