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The discovery of the tilted shoreline linked to precession etc seems to confirm a Young Wet Mars...
Okay, I'll not get into the knotty issue of 'when last', whether 1 aeon ago, or three...
Given a time when parts of Mars were wet, so above freezing at sea level, what would conditions have been like in Valles Marineris ??
That's a big, big canyon. How many miles deep ?? Five ?? Yeah, right...
IMHO, nearest Terrestial equivalent would be the Messinian Event, when the Med dried up.
Are there any estimates of temperatures, pressures and weather atop the plateau, mid-wall and down in the Valles Bottomlands ??
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Similar question applies to Terraformed Mars. Assuming enough cometary imports to raise atmospheric pressure to 'flowing water' for a few millenia, enough greenhouse to thaw those caps...
Will Mars be 'Out Of The Silent Planet', with 'High Plains' / Andean Plateau conditions in Marineris and 'Everest' everywhere else ??
What's the lapse rate ??
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Cross-posted to this sub-forum in desperation...
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Are there any estimates of temperatures, pressures and weather atop the plateau, mid-wall and down in the Valles Bottomlands ??
This is a very tricky question since the answer depends on what the conditions of the MEGAOUTFLO event leave the planet. The scale height of Mars is 11 km so everytime you go 11 km above the datum, the air pressure drops to 1/e what it was at the datum. 5 miles is about 8 km so assuming that the floor of the Valles M. bottom lands are close to the datum (likely a good guess) then the air pressure at the top would be about 27% as thick as at the bottom.
Guesses were that early in Mars' history it had a CO2 atmosphere around 3 bars. This would mean that at the top of the rift valley would have a pressure of around 1 bar.
Most of the MEGAOUTFLO events took the average temperature of Mars up to a few degrees below zero. However Valles M. is near the equator, at low attitude and so would expect near the maximum warming. As a wild guess I would venture that perhaps 1/3 of the year's days it would have temperatures topping 0. So you would expect a lot of water running under frozen surfaces or glaciers. Further up the walls there would be frost, ice and water under permafrost. (Back then Mars' ground was a lot warmer...) Expect glaciers everywhere.
Similar question applies to Terraformed Mars. Assuming enough cometary imports to raise atmospheric pressure to 'flowing water' for a few millenia, enough greenhouse gasses to thaw those caps...
Will Mars be 'Out Of The Silent Planet', with 'High Plains' / Andean Plateau conditions in Marineris and 'Everest' everywhere else ??
What's the lapse rate ??
The questions above are unanswerable because it is anyone's guess at how far terraforming will proceed. My gut feeling is that terraforming can takes us with out too much trouble to Andean Plateau in the low laying areas. But it will take a lot more effort to make the high lands places where Earth animals will survive. So (my guess) is that the low, equatorial areas will be like the coldest areas on Earth and the higher areas will be left to the lichen and glaciers.
Lapse rate: The estimates are that MEGAOUTFLO events die out within millions of years after the volcanic eruptions that created them stops.
Warm regards, Rick.
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