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These are the computed values of an Earthlike atmosphere on Mars with a comparison to Earth.
Earth
Troposphere - 0 to 8-15 km (high and middle latitudes) - 0 to 16-18 km (low latitudes) - Normal clouds
Tropopause - Upper boundary of the troposphere
Stratosphere - 18 to 50 km - Ozone layer
Stratopause - Upper boundary of the Stratosphere
Mesosphere - 50 to 80 km - Meteors
Mesopause - Upper boundary of the mesosphere
Ionosphere (Thermosphere) - 80 to 1000 km - Aurora
Exosphere - Over 1000km
Altitude increment at which atmospheric pressure increases by a factor of 10 = 18 km
Mars
Troposphere - 0 to 21-39 km (high and middle latitudes) - 0 to 42-47 km (low latitudes) - Normal clouds
Tropopause - Upper boundary of the troposphere
Stratosphere - 47 to 131 km - Ozone layer
Stratopause - Upper boundary of the Stratosphere
Mesosphere - 131 to 210 km - Meteors
Mesopause - Upper boundary of the mesosphere
Ionosphere (Thermosphere) - 210 to 2619 km - Aurora
Exosphere - Over 2619 km
Altitude increment at which atmospheric pressure increases by a factor of 10 = 47.15 km
Earthlike Atmosphere
Composition of Lower Atmosphere
Nitrogen 78.08%
Oxygen 20.95%
Argon 0.93%
Carbon dioxide 0.03%
Neon 18.18 * 10^-1%
Helium 5.24 * 10^-4%
Krypton 1.14 * 10^-4%
Xenon 0.09 * 10^-4%
Hydrogen 0.5 * 10^-4%
Methane 2.0 * 10^-4
Nitrous oxide 0.5 * 10^-4
Very slight, varioable traces of sulphur dioxide and carbon monoxide
The amount of water vapour is variable; in the range of 1%
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So what kind of greenhouse effect is this going to have?
Is Mars under these conditions a cold place or a warm place?
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http://en.wikipedia.org/wiki/Atmospheric_pressure
http://hyperphysics.phy-astr.gsu.edu/hb … arfor.html
How do those Martian figures compare to Terrestial pressure / altitude tables for the bottom five or ten miles ??
http://sablesys.com/baro-altitude.html
Per my question in other sub-forum, what would the conditions be in / around Valles Marineris ??
My naive reading of the numbers suggests that Mars' pressure drops slower with altitude than Earth's so, for valley-floor at 15 PSI, Marineris' rim would be 'Everest High Camp' rather than 'Everest Peak'. Is this so ??
Similarly, if the rim was 'Andean Altiplano', what would conditions be like at mid-wall and down in the Bottomlands ??
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My assumptions are that the Earth's Atmospheric composition is replicated on Mars with 1 Bar or pressure at the 0 datum which is assumed to be Martian Sea Level. Those parts of Valles Marineris that are below this altitude would be under water as it would connect with the Northern Ocean forming a channel with steep walls. One has to look at the altitude of Everest and the Altitude of Olympus Mons and correct for the more gradual diminishing of atmosphere for Mars than for Earth, then you would get a sense of what Earth equivalent altitude Olympus Mons would be. As I stated above Earth's atmosphere diminishes by a factor of 10 every 18 km, and Mars does the same every 47.15 km, that's true today and it would be true with a terraformed atmosphere. I think water would be transported over Mars with less rain shadow effect when passing over mountains than occurs on Earth. Mars has higher mountains though and is further from the Sun. Perhaps Mars would end up with a more uniform temperature than Earth as the Greenhouse effect would be greater because its atmosphere would stack higher to create the same 1 bar pressure at sea level than it would for Earth.
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Many people who really haven't studied keep assuming a terraformed planet must be EXACTLY the same as Earth. That's wrong. First, you don't require the same diluent gas as Earth. Earth just happens to have it.
You need a minimum of ~150 millibar partial pressure oxygen to breathe; 200mbar PP O2 would be nice. Second you need ozone in the upper atmosphere to block UV. Third you need some carbon dioxide and nitrogen to feed plants. To keep the planet warm, you also need some greenhouse gasses to trap IR light: PFCs and SF6, perhaps some BrCF3. You also need to layer the atmospher, a cold trap to keep water in the lower atmosphere. Snow won't rise too far; besides, snow won't escape gravity.
Here on Earth we have ~0.03% CO2, but we can breathe up to 2% CO2 for hours without any ill effects. We can handle lower pressure as long as we can breathe, and as long as pressure is above the point where blood will boil at body temperature. That pressure is well below 100mbar and vascular pressure is sufficient to keep blood pressurized above that anyway, so focus on breathing.
This means we could walk outdoors and plants could grow with 150mbar O2, 0.3 mbar CO2, and just a little N2. Since protein has less nitrogen than carbon, and plants have a mixture of carbohydrates and protein, that means plants could grow with less nitrogen than carbon in the atmosphere. Let's make a wild guess: 0.1mbar N2. Mars currently has 2.7% N2, and pressure about 7mbar so the PP N2 is 0.189mbar. That's good news, it means plants can fix nitrogen with the amount of nitrogen Mars atmosphere currently has. However, if we grow a planetary biosphere the plants will consume a lot; we will need more. Hopefully there are nitrate deposits under the soil somewhere.
Bottom line: expect Mars will always have lower pressure than Earth.
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Disclaimer: I've truncated some trailing decimals, and it is a long, long time since I've wrangled a graph...
Given:
0 km altitude 100% pressure, Plog10 =2
47 km altitude 10% pressure, Plog10 =1
94 km altitude 1% pressure, Plog10 =0
y = a*x + b
2=a*0 + b, so b=2
0=a*94 +2, so a = -2/94
so Plog10 = 2 - ht * 2 / 94
And assume 100% = 15 psi for comparison...
km % psi
0 _ 100 _ 15.0
1 _ 95.2 _ 14.3
2 _ 90.7 _ 13.6
3 _ 86.3 _ 13.0
4 _ 82.2 _ 12.3
5 _ 78.3 _ 11.7
6 _ 74.5 _ 11.2
7 _ 71.0 _ 10.6
8 _ 67.6 _ 10.1
9 _ 64.3 _ 9.7
10 _ 61.3 _ 9.2
Okay, Tom, does this compute ??
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Yeah, the math seems good.
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Many people who really haven't studied keep assuming a terraformed planet must be EXACTLY the same as Earth. That's wrong. First, you don't require the same diluent gas as Earth. Earth just happens to have it.
You need a minimum of ~150 millibar partial pressure oxygen to breathe; 200mbar PP O2 would be nice. Second you need ozone in the upper atmosphere to block UV. Third you need some carbon dioxide and nitrogen to feed plants. To keep the planet warm, you also need some greenhouse gasses to trap IR light: PFCs and SF6, perhaps some BrCF3. You also need to layer the atmospher, a cold trap to keep water in the lower atmosphere. Snow won't rise too far; besides, snow won't escape gravity.
Here on Earth we have ~0.03% CO2, but we can breathe up to 2% CO2 for hours without any ill effects. We can handle lower pressure as long as we can breathe, and as long as pressure is above the point where blood will boil at body temperature. That pressure is well below 100mbar and vascular pressure is sufficient to keep blood pressurized above that anyway, so focus on breathing.
This means we could walk outdoors and plants could grow with 150mbar O2, 0.3 mbar CO2, and just a little N2. Since protein has less nitrogen than carbon, and plants have a mixture of carbohydrates and protein, that means plants could grow with less nitrogen than carbon in the atmosphere. Let's make a wild guess: 0.1mbar N2. Mars currently has 2.7% N2, and pressure about 7mbar so the PP N2 is 0.189mbar. That's good news, it means plants can fix nitrogen with the amount of nitrogen Mars atmosphere currently has. However, if we grow a planetary biosphere the plants will consume a lot; we will need more. Hopefully there are nitrate deposits under the soil somewhere.
Bottom line: expect Mars will always have lower pressure than Earth.
150mbar may be sufficient, but why settle for sufficiency? If we are going to muster the resources to terraform Mars, why not do a good job of it? After some thought it occurs to me that there are some advantages to a 1000mbar atmosphere on Mars, for one its easier to fly. You could not only have airplanes with short stubby wings, you could also have flying cars. With only 1/3rd of Earth's gravity and the same air pressure as on Earth, it becomes much easier to land vertically, a vehicle such as this has been proven to fly on Earth, of the Mollier design, on Mars with less gravity to fight, you need less horsepower to lift off the surface, you be able to land vertically on your driveway and park your vehicle in your garage, and also thanks to the low gravity the Martian atmosphere stacks much higher than on Earth so you'll be able to fly higher as well. Under Martian gravity, terminal velocity is lower in a 1000mbar atmosphere than on Earth, one can fall from greater heights without serious injury, parachutes can likewise be smaller, and if your aircar engines fail, you can land your vehicle gently with a paracute assist. With all this air traffic, you have less need for roads, less infrastructure to maintain etc.
Another benefit of a thicker atmosphere is more efficient transport of water from over the oceans to the land. The high atmosphere reduces the rainshadow effect that mountains cause so their will be fewer deserts. The greenhouse effect would make Mars a warm and lush tropical planet and its thick ozone layer coupled with the increased distance to the Sun will make it very hard to get a suntan or a sunburn on Mars. People with very pale skin will do very well here swinging from the tropical jungles of terraformed Mars, under the gentle sunlight of the distant sun. Mars can easily by much more hospitable that Earth, and since it is an engineered jungle, there would be no tropical diseases, or poisonous reptiles and insects.
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Heavens !! Marineris could resemble a chunk of the 'golden age' tropical-swamp Venus that never was...
How big could you grow rain-forest or mangrove in low g ?? Most of that flora is pre-adapted to thrive in shadow-- which would be tree-top illumination on Mars.
If you don't mind, I'll pass on the Brontosaurus, though I imagine feral pigs might get rather large...
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Just because Mars is in our imagination a desert world does not mean we have to make that desert world with the thin atmosphere and arid deserts irrigated by canals. Remember the Mars of E. R. Burrows was a dying world with a more verdant past. Why not make a more verdant world in the first place, then when it loses some of its atmosphere, it will still be habitable. If the atmosphere is merely sufficient to support human life, that means if it is not maintained, it will after a shorter time become insuficient to support human life. Titan's atmosphere is stacked even more and is more massive than Earth's. If we could just transport some of that atmosphere to Mars, and combine it with whatever we could cook our of Mars' crust, that seems to be the way to go.
And yes, a low gravity world will tend to breed large animals, and a thick atmosphere might have some rather large flying birds as well.
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Where are you going to get all that nitrogen or argon? Argon is a noble gas, it doesn't chemically combine with anything. That means atmospheric argon is all that's there, it's all you will ever get. The same is true of neon, xenon, and krypton. As for nitrogen, I have argued that detection of atmospheric ammonia by Mars Express does imply nitrate deposits, but we have no proof they exist and no way of estimating how much is there.
My calculations start with a computation of what is minimum so we can compare that to what we know to be there. Once we see available resources exceed the minimum, it means we can terraform. Estimates of Mars CO2 published in Martyn J. Fogg's book "Terraforming: Engineering Planetary Environments" quotes estimates from published science papers. One referece estimates Mars CO2 budget as 200mbar once it is all sublimated, the other estimates is 300mbar. The question is how much CO2 is adsorbed on soil particles beneath the surface.
Your "pie in the sky" calculations are based on fantasy, not any science results of available resources.
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Hi. I'd posted several queries about conditions in Marineris during the proposed 'Warm Wet' Precambrian, but had no reply...
D'uh, I only wanted the info for an argument between two characters in a story: given 'Andean High Plateau' at the rim, what of the Bottomlands ? Would hypothetical residents crave Raj-era hill-stations above the fug ??
Well, probably, yes-- which what my intuition suggested. I may battle with half-forgotten math and unfamiliar atmospheric physics to put better numbers on it, but I reckon I was close enough...
IMHO, Terraforming 'our' Mars to 'temperate' in the Bottomlands would be a Great Project, something that would rank beside the Great Pyramids for sheer gall.
Agreed, the current inventory of Martian volatiles is almost certainly inadequate for terraforming-- well, there's no Moon stirring the tectonics, no free water to feed the continental conveyor and flush volcanic volatiles, that lower gravity let the legacy atmosphere billow, aeons of solar wind barely hindered by a weak magnetosphere stripped it away etc etc
Perhaps the permafrost extends much, much deeper than the data suggests, but I'd not bet on it...
Never mind what Mars had, the current inventory offers little better than stratosphere: There's just enough to be tempting...
FWIW, I've a copy of Martyn's book shelved some-where, and consider it a 'tour de force'.
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Where are you going to get all that nitrogen or argon? Argon is a noble gas, it doesn't chemically combine with anything. That means atmospheric argon is all that's there, it's all you will ever get. The same is true of neon, xenon, and krypton. As for nitrogen, I have argued that detection of atmospheric ammonia by Mars Express does imply nitrate deposits, but we have no proof they exist and no way of estimating how much is there.
My calculations start with a computation of what is minimum so we can compare that to what we know to be there. Once we see available resources exceed the minimum, it means we can terraform. Estimates of Mars CO2 published in Martyn J. Fogg's book "Terraforming: Engineering Planetary Environments" quotes estimates from published science papers. One referece estimates Mars CO2 budget as 200mbar once it is all sublimated, the other estimates is 300mbar. The question is how much CO2 is adsorbed on soil particles beneath the surface.
Your "pie in the sky" calculations are based on fantasy, not any science results of available resources.
Terraforming Mars in general is pretty much "pie in the Sky" anyway, We have no such capability whatsoever to Terraform Mars now, seeing how all we've done so far is send a few probes to the planet. Planetary engineering is much beyond us right now. The question only is to how much a degree do you want to terraform Mars. A more thorough Terraformation requires a greater marshalling of resources. You seem to take the tack that we can only use resources that are already on Mars. One thing that does not seem to be on Mars is an Ocean. I'm not sure how much water is underground, but I doubt there is enough to make an ocean.
If we can get to Mars in a big way so we can terraform it, we can also travel to the comets. I very much doubt that we'll have a scenario where there is an empty Solar System while their are millions of people living on Mars and Earth. Millions of people at least will have to call Mars their home before we can even consider terraforming the place, and by that time our interplanetary transportation network will be so well established that we'll have people living on the Asteroids and on the Moon as well. Getting to the outer solar system requires a high efficiency low thrust engine. We will probably travel their in asteroid ships and mobile colonies.
There is nitrogen in the outer solar system, most notably Titan, but probably also in the short period comets beyond Pluto. If we bombard Mars with comets we can increase its atmospheric mass, we basically have to arrest most of each comet's orbital motion and they will fall sunward and if they are aimed precisely enough they will hit Mars. Out beyond Pluto there's likely to be frozen nitrogen. If we can just shade it from the Sun as each one falls sunward, we can keep them frozen until they reach Mars.
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Mars Oddysey used a gamma ray spectrometer and a suite of neutron spectrometeres to measure radiation reflected from Mars. The idea was solar wind impacts Mars surface since there's no magnetosphere, use that radiation as your illumination source. There is no neutron radiation in space, the only neutron radiation came from the surface. By comparing the concentration of high speed neutrons to epithermal neutrons, there were able to detect how much epithermal neutron radiation was absorbed in the top portion of Mars soil. That may seem esoteric, but that's how the measured hydrogen in the top metre of Mars soil. There was a hell of a lot more than anyone expected. In fact, there's so much that it couldn't all be hydrated minerals such as clay, it has to be water ice. That led them to suspect there is permafrost under the soil. If so, some places near the south pole had so much water that ever 2 buckets of soil would yeald 1 bucket of water.
This lead the European Space Agency to launch Mars Express with a ground penetrating radar. The Mars Odyssey data didn't say how deep the water went, ground penetrating radar would answer that. They found found the south pole had much less dirt and dust than they thought, it's basically a polar ice cap covered over with dirt. At its centre, the polar ice cap is 3.7 km thick! There is so much water that if it all melted it could cover the surface of Mars with a layer 11 metres deep. Of course it wouldn't cover the surface evenly, it would run down hill. In fact there's about enough water to fill the ancient ocean basin in the north. So we found where the ocean water went; it's still there.
Sorry to disagree with you yet again, but there is enough water for an ocean. I don't know if it's enough to fill the ancient ocean basin to it's lip, but there is enough for an ocean.
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Even if there is not enough, there is still plenty of ice in the Solar System.
Perhaps we may utilize the local resources to terraform Mars, and then later thicken up the Atmosphere to Earth's Sea Level pressure, that will make a terraformed Mars longer lived as it can then lose substantial atmosphere yet remain habitable. Have Mars start out as a warm wet place, and maybe evolve into something resembling more of the classic Mars of our imagination, but for habitablity, I wouldn't want a lot of desert. Desert doesn't contribute much to the recycling of carbon dioxide into oxygen, and a warm lush Mars would support more inhabitants than an arid dry Mars would. I wouldn't want a destert planet with a breathable atmosphere and canals for irrigation. Seems to me that if we could modify a planet, we might want to do it all the way, if the surface looks more like golden age Venus instead of Mars, so what of it. I think its possible for Mars to be mostly land with the minority of its surface being ocean yet have most of the land covered in forest. The thick atmosphere ought to carry much more water vapor per land area that Earth's atmosphere would. A cumulo nimbus cloud would appear to be vertically stretched as compared to terrestrial standards for thunderheads., and it would dump more rain on the ground than an equivalent terrestrial cloud too. Rain clouds would sail right over the highest peaks. One could breath on the Summit of Mt Olympus without assistance etc.
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