Challenges of Terraforming Mars: Temperature, Air Pressure, and Radiation

In summary, the main problems that need to be addressed in order to potentially terraform Mars are the temperature, air pressure, air composition, and weak magnetosphere. While the temperature and air pressure could potentially be solved by heating up the planet, the main obstacle is the toxic air composition primarily made up of carbon dioxide. Additionally, the effects of radiation due to the weak magnetosphere need to be considered. Even if these issues are addressed and the planet is filled with plants and organisms, it would still be a massive undertaking to create a functioning ecosystem. It is currently not feasible to fully terraform Mars, but it may be possible for humans to live there with protective suits and some level of adaptation.
  • #36
Hells said:
Can increasing the thickness of the atmosphere compensate for lack of a magnetic field?

This is a common misunderstanding. Earth's atmosphere provides us with protection from radiation, not the magnetosphere. There's 10 tonnes of air above every square meter of Earth which stops radiation from flares and high-energy cosmic rays. The magnetosphere diverts the solar wind and coronal mass ejections, but neither of those is especially harmful as their average particle energy is low. That might sound odd, because of those deadly Van Allen Belts trapped by Earth's magnetic field. But those same Belts are trapped around Earth by the magnetic fields and the deadly radiation is from high-energy cosmic rays smashing into the atmosphere and the resulting particles being trapped.

Even more debatable is whether the magnetic fields stopped/stop atmospheric escape - Venus has no field and lots of air - or whether Mars lost its atmosphere just because it was too small.
 
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  • #37
qraal said:
Even more debatable is whether the magnetic fields stopped/stop atmospheric escape - Venus has no field and lots of air - or whether Mars lost its atmosphere just because it was too small.

As I understood it the protection the magnetosphere was mainly due to the magnetic bowshock redirecting solar winds that would otherwise strip our atmosphere away fairly quickly.

This is not debatable as far as I am aware so I will try and dig out some supporting papers - I am fairly certain this is known science.
 
  • #38
Cosmo Novice said:
As I understood it the protection the magnetosphere was mainly due to the magnetic bowshock redirecting solar winds that would otherwise strip our atmosphere away fairly quickly.

This is not debatable as far as I am aware so I will try and dig out some supporting papers - I am fairly certain this is known science.

Presently the solar wind strips the atmosphere of Mars away at a few kilograms per second. Earth's loss rate would be even lower. The solar wind was, based on observations of young stars extrapolated to our own, perhaps 1,000 times stronger in the past. Thus the basis of the claim it can strip atmospheres away. But not anymore. Takes billions of years nowadays.
 
  • #39
Pilot7 said:
I think it was Kelvin who said around 1900 something like (my paraphrase): We have now pretty much resolved all the issues in physics, the hard part is done, we are just sorting out some details now...
This supposed quote is a bit off-topic, but since this is a widely-replicated supposed quote, it merits correction. You are talking about a quote along the lines of this one at scienceworld.wolfram.com, "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement." That quote was supposedly made in Thomson's 1900 address to the British Association for the Advancement of Science, "Nineteenth Century Clouds over the Dynamical Theory of Heat and Light."

A funny thing about that quote: It's false. You can find the text of the speech here, printed two years after the speech: http://books.google.com/books?id=YvoAAAAAYAAJ&pg=PA363&lpg=PA363#v=onepage&q&f=false.
 
  • #40
qraal said:
Presently the solar wind strips the atmosphere of Mars away at a few kilograms per second. Earth's loss rate would be even lower. The solar wind was, based on observations of young stars extrapolated to our own, perhaps 1,000 times stronger in the past. Thus the basis of the claim it can strip atmospheres away. But not anymore. Takes billions of years nowadays.

Can you please link a supporting article/source, I find this really interesting.

thanks in advance
 
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  • #41
Cosmo Novice said:
Can you please link a supporting article/source, I find this really interesting.

thanks in advance

Energy balance and momentum of the present solar wind is enough to demonstrate that. But do a Google on the mass loss rate from Mars at present. Alternatively have a look at the NASA ADS and do a fuller search.
 
  • #42
Hells said:
Can increasing the thickness of the atmosphere compensate for lack of a magnetic field?

Yes, it can. Engineering the atmosphere could even stop UVC radiation.

Anyway, not to piss people off again, but much of the solar radiation, except the UV and onwards electromagnetic radiation, reaching Mars is quite harmless isn't it? Electromagnetic radiation with >400nm wavelength and some alpha particles (these ones don't reach Earth due to the magnetosphere).

A few (100?) rads of alpha particles/+ions here and there won't really hurt anyone in an enclosed suit.
 
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  • #43
Nikitin said:
Yes, it can. Engineering the atmosphere could even stop UVC radiation.

Anyway, not to piss people off again, but much of the solar radiation, except the UV and onwards electromagnetic radiation, reaching Mars is quite harmless isn't it? Electromagnetic radiation with >400nm wavelength and some alpha particles (these ones don't reach Earth due to the magnetosphere).

A few (100?) rads of alpha particles/+ions here and there won't really hurt anyone in an enclosed suit.

People were not "pissed off". They were getting frustrated because you were handwaving away very complex, technical and interesting issues that they had taken the time to explain to you (remember no one is under any obligation to do that).

I am unsure about how bad the radiation would be on Mars if there were a thick atmosphere, the atmosphere on Mars would have to be much thicker than that of Earth's to account for the face that Mars has a lower gravity. This means an equal amount of atmosphere would not cause the same pressure obviously necessary for life.

Leading on from this the atmosphere engineering of Mars could have much harder problems to solve, if the atmosphere needs to be 3x thicker to provide the same pressure then we may have problems with the amount of radiation absorbed. In addition martian weather systems could be drastically different from Earth's if the atmosphere was much denser, how this would effect the ecology would have to be carefully considered.

As this goes on more and more I feel that space habitats are a far better option and that to even begin terraforming we are going to need a knowledge of synthetic biology far, far beyond that of today.
 
  • #44
Why do you have to account for ecology? The only cycle you would have to consider is O2+Cx --> CO2 + H20 --> Cx + O2
On Earth plants are responsible for sequestering Carbon from CO2, but it should be possible to design machines that do the same,
Energy consumption per human: 2200 Kcal = 9 204.8 kJ
Since all the energy comes from oxidation of fuel, we need at least this number of energy to make oxygen. Let's assume that our machine can reverse the reaction with 20% efficiency, the machine will require energy of 46002 kj per human per day to turn CO2 into Cx + O2 to not see a decrease in [O2]. 3600 kJ = 1 kilowatt-hour

The only problem is if our water doesn't condense because there's too low amount of it available, and it will never saturate parts of the atmosphere. Water will be locked in as humidity. A machine can help here as well, by pressuring a part of the atmosphere in a containment vessel.

Terraforming just means making a planet suitable for human habitation, it doesn't mean make it suitable for plant or animal life. Farming could be in sealed domes, with import of specialty nutrients. (bulk water, O2 and CO2 would be available.)
 
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  • #45
Hells said:
Why do you have to account for ecology? The only cycle you would have to consider is O2+Cx --> CO2 + H20 --> Cx + O2
On Earth plants are responsible for sequestering Carbon from CO2, but it should be possible to design machines that do the same,
Energy consumption per human: 2200 Kcal = 9 204.8 kJ
Since all the energy comes from oxidation of fuel, we need at least this number of energy to make oxygen. Let's assume that our machine can reverse the reaction with 20% efficiency, the machine will require energy of 46002 kj per human per day to turn CO2 into Cx + O2 to not see a decrease in [O2]. 3600 kJ = 1 kilowatt-hour

The only problem is if our water doesn't condense because there's too low amount of it available, and it will never saturate parts of the atmosphere. Water will be locked in as humidity. A machine can help here as well, by pressuring a part of the atmosphere in a containment vessel.

Terraforming just means making a planet suitable for human habitation, it doesn't mean make it suitable for plant or animal life. Farming could be in sealed domes, with import of specialty nutrients. (bulk water, O2 and CO2 would be available.)

A good technologist uses the best available technology for the task. Self-replicating bioconverters - i.e. bacteria, archaea, plants and animals - are amazingly more advanced than our current best efforts. Employing very high-power technology for raw conversion of a planet is attractive because it shortens the time-table immensely, but how long does it take to make such a uber-tech system powerful enough?

Paul Birch considered these issues for both Mars and Venus in a duology of papers "Terraforming Mars Quickly" and "Terraforming Venus Quickly". Look them up on "Google" and educate yourselves. The size requirements of the necessary machines is breath-taking and requires a very large in-space economy.
 
  • #46
1. I am talking about upkeep
2. Haven't we already established that the bioconverters require an ecosystem? That's what we wish to eliminate. We can, for example, use artificial photosynthesis.
 
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  • #47
Hells said:
1. I am talking about upkeep
2. Haven't we already established that the bioconverters require an ecosystem? That's what we wish to eliminate. We can, for example, use artificial photosynthesis.
That is a solution in a hand-wavy, science fiction world where perpetually-TRL 1 technology can solve all of the world's problems.

This site is not such a world. We have rules against overly-speculative posts, and this thread has tons of such. Keep it real please, or this thread is locked.
 
  • #48
How can you add an atmosphere of sufficient pressure if the gravity on Mars is only about 1/3 of Earths? Especially once it heats up. Wouldn't much of it disappear?
 
  • #49
No I don't think so. At least not the CO2. The gas needs to get an appropriate escape velocity first.

Though due to the lack of a proper magnetosphere Mars' atmosphere will constantly decay, tho it'l take many millions of years b4 the result is noticeable.

Ryan: I believe the radiation would be somewhere around 2 millirads/day or so on average today for a human on Mars, with the increase coming mostly from + charged ions. I don't think that will hurt anyone once Mars has a proper atmosphere.

I don't think the atmosphere needs to have 3x the molar density than Earth's just because of the lack of gravity.. The pressure equilibrium would obviously arrange itself different from Earth's though and so we'd need some more.

I don't anything about fluid dynamics, so if you read the paper from the NASA physicist which I provided in page 2 you'd see it would be, most likely, doable with just the CO2 reserves in the Martian soil & the dry ice.
 
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  • #50
Nikitin said:
Yes, it can. Engineering the atmosphere could even stop UVC radiation.

Anyway, not to piss people off again, but much of the solar radiation, except the UV and onwards electromagnetic radiation, reaching Mars is quite harmless isn't it? Electromagnetic radiation with >400nm wavelength and some alpha particles (these ones don't reach Earth due to the magnetosphere).

A few (100?) rads of alpha particles/+ions here and there won't really hurt anyone in an enclosed suit.

The solar wind gets mostly deflected around the present day Martian and Venusian atmospheres via their ionospheres, the charges being enough to deflect much of the wind around the planets. A bit of atmosphere is stripped away - the total having been measured by Mars Express as a couple of kilograms a second - but nowhere near enough to strip the atmosphere away in less than aeons. The radiation that reaches the surface that is of concern during solar flares is from x-rays. Cosmic-rays are significantly higher, but no more so than what is encountered on the ISS. On Earth they run into gas molecules much higher up and their secondary radiation has mostly decayed into muons by the time it reaches the surface.
 
  • #51
Drakkith said:
How can you add an atmosphere of sufficient pressure if the gravity on Mars is only about 1/3 of Earths? Especially once it heats up. Wouldn't much of it disappear?

No. The escape velocity at the exosphere is sufficiently high for even a warm atmosphere to be retained indefinitely. Especially if it remains mostly carbon dioxide, which reduces the exosphere's temperature thanks to more efficient IR emission.
 
  • #52
Nikitin said:
I don't think the atmosphere needs to have 3x the molar density than Earth's just because of the lack of gravity.. The pressure equilibrium would obviously arrange itself different from Earth's though and so we'd need some more.

The column mass has to be higher, but the molar density can be whatever so long the total mass is enough to provide the surface pressure by its weight.
 
  • #53
Hells said:
Why do you have to account for ecology? The only cycle you would have to consider is O2+Cx --> CO2 + H20 --> Cx + O2
On Earth plants are responsible for sequestering Carbon from CO2, but it should be possible to design machines that do the same,
Energy consumption per human: 2200 Kcal = 9 204.8 kJ
Since all the energy comes from oxidation of fuel, we need at least this number of energy to make oxygen. Let's assume that our machine can reverse the reaction with 20% efficiency, the machine will require energy of 46002 kj per human per day to turn CO2 into Cx + O2 to not see a decrease in [O2]. 3600 kJ = 1 kilowatt-hour

The only problem is if our water doesn't condense because there's too low amount of it available, and it will never saturate parts of the atmosphere. Water will be locked in as humidity. A machine can help here as well, by pressuring a part of the atmosphere in a containment vessel.

Terraforming just means making a planet suitable for human habitation, it doesn't mean make it suitable for plant or animal life. Farming could be in sealed domes, with import of specialty nutrients. (bulk water, O2 and CO2 would be available.)

Ok this thread is starting to go off of the rails. There have been many posts explaining why an ecology is necessary for life. Hand-waving "if we had a machine" is not useful. You've also not considered the necessity for an ecology to sustain farming, provide the 1kg of gut flora humans need to survive etc etc
 
  • #54
qraal said:
The column mass has to be higher, but the molar density can be whatever so long the total mass is enough to provide the surface pressure by its weight.

Yes, you are right, heavier gases will obviously concentrate themselves on the surface, though still, having increased molar density will be a must once the makeup of the Martian atmosphere is getting engineered to be similar to that of Earth.

Anyway, to the main point, CO2 is quite a heavy gas, and there are most likely sufficient quantities of it on Mars.

As for your second post, good to know that the radiation isn't too bad on Mars, except during Solar flares. Unfortunately I have no clue about Muons, haven't had about them in class yet.
 
  • #55
qraal said:
The column mass has to be higher, but the molar density can be whatever so long the total mass is enough to provide the surface pressure by its weight.

What effect would a different molar density have on life though? These are incredibly fine systems, slight changes could have catastrophic effects on the environment.
 
  • #56
Well, would a high concentration of CO2 in the air really be harmful for the photosynthesis-organisms (and the organisms they need to survive, if they need any)?

Anyway, I don't think the molar density of the air close to the surface of a completely terraformed Mars would be particularly higher than on earth.

Though in the outer layers of the (completely terraformed) Martian atmosphere I'd think the molar density would be significantly higher than in the outer layers of Earth's atmosphere.
 
  • #57
Nikitin said:
Anyway, I don't think the molar density of the air close to the surface of a completely terraformed Mars would be particularly higher than on earth.

Though in the outer layers of the (completely terraformed) Martian atmosphere I'd think the molar density would be significantly higher than in the outer layers of Earth's atmosphere.

What makes you think the density on the ground could be the same as Earth but the density in the outer layers could be higher?
 
  • #58
You should read the Red Mars Trilogy by Kim Stanley Robinson (Red Mars, Green Mars, Blue Mars). This is in my opinion one of the best science fiction series that has ever been written about colonizing another planet. The story revolves around the science and engineering involved with regards to the application of terraforming Mars, creating a new government, the relationship to Mars and Earth, and the psychological and sociological aspects of living on a different planet and trying to survive. Excellent excellent excellent.
 
  • #59
Nirgal, perhaps you should start reading something a bit more reliable than science fiction. Robinson's Mar's Trilogy revolves around Robinson's politics. Everything else, the bad plot, the bad characters, and the bad science, takes second shrift to this barely-disguised socialist diatribe.
 
  • #60
D H said:
Nirgal, perhaps you should start reading something a bit more reliable than science fiction. Robinson's Mar's Trilogy revolves around Robinson's politics. Everything else, the bad plot, the bad characters, and the bad science, takes second shrift to this barely-disguised socialist diatribe.

Ah, I see you don't enjoy that novel because of your own politics. I tend not to judge fiction based on my disagreements with what occurs in the story. Considering that the book won Hugo, Clark, Locus, and Nebula awards, I would suggest that your opinions do not reflect that of the majority.

What would you have me read?
 
  • #61
ryan_m_b said:
What makes you think the density on the ground could be the same as Earth but the density in the outer layers could be higher?

Because Mars has a weak gravity. Extra gas would be needed to compensate for this. I.e. the air-pressure from above on the air below must compensate for the lack of gravity.

Well this is what I think is the reason

As for the "red colony book".. Kim Stanley has a degree in literature, not in any scientific subject.. This kind of ruins his credibility and thus the book for me :P
 
  • #62
Nikitin said:
Because Mars has a weak gravity. Extra gas would be needed to compensate for this. I.e. the air-pressure from above on the air below must compensate for the lack of gravity.

Well this is what I think is the reason

As for the "red colony book".. Kim Stanley has a degree in literature, not in any scientific subject.. This kind of ruins his credibility and thus the book for me :P



Have you ever heard of the Genetic Fallacy? It's a type of argument or conclusion drawn from a person's background, origin, or history rather than the actual claims that the person makes. It is called a fallacy because it is an incorrect method of analysis.

If you read this book you'll see that Kim Stanley Robinson has done his research. What degree would you like him to have if you would feel better about reading it? Terraforming is a diverse interdisciplinary theoretical topic. There does not exist a degree that can cover every aspect.

As someone who has studied physics and has taken classes in planetary atmospheres and glacier physics, I think that he does an excellent job of portraying the science (that I am familiar with).

Also, its called science fiction. I still like Enders Game though I do not believe in faster-than-light communication.
 
  • #63
Nirgal said:
As someone who has studied physics and has taken classes in planetary atmospheres and glacier physics, I think that he does an excellent job of portraying the science (that I am familiar with).

That remark brings an xkcd comic to mind:

physicists.png


Physicists can be incredibly, well, dense, when it comes to fields that our outside their expertise. ryan_m_b has elaborated on the difficulties of developing an ecology. These concerns have been largely ignored. ryan and I have discussed the issue of the TRL 1 technologies hypothesized as terraforming mechanisms in this thread. These concerns have similarly been largely ignored.

Also, its called science fiction. I still like Enders Game though I do not believe in faster-than-light communication.
Right. And this site is about science, not science fiction.

Robinson did get one thing right in his books, and that is the Red movement. The underlying weltanschauung of this movement is in fact the current policy of NASA and supposedly of all of the nations that have signed the Outer Space Treaty. Probes sent to Mars are built under extreme clean room conditions, are sterilized prior to launch, and are exposed to vacuum and solar radiation during transit, all to avoid contaminating Mars -- and we still worry that we aren't doing enough. We do this just on the off chance that life might exist on Mars. All bets on terraforming Mars will be off should some probe find incontrovertible proof of life on Mars. The Red movement exists right now, and it has quite a bit of say on the NASA Advisory Council.

Speaking as a mentor:

This thread has been skating on very thin ice for quite some time per the PhysicsForums rules on overly speculative posts. Keep the posts real or this thread will be closed.
 
  • #64
Nikitin said:
Because Mars has a weak gravity. Extra gas would be needed to compensate for this. I.e. the air-pressure from above on the air below must compensate for the lack of gravity.

Well this is what I think is the reason

Huh? If you put gas on top of gas it doesn't sit there and push the lower gas down, it sinks into the lower gas. You can't have a higher density floating above a lower.

I agree with D H, the scientific problems with terraforming have been adequately outlined (along with a host of others), I don't see this thread as going anywhere productive if it starts citing science fiction.
 
  • #65
ryan_m_b said:
Huh? If you put gas on top of gas it doesn't sit there and push the lower gas down, it sinks into the lower gas. You can't have a higher density floating above a lower.

I agree with D H, the scientific problems with terraforming have been adequately outlined (along with a host of others), I don't see this thread as going anywhere productive if it starts citing science fiction.
that was not what I meant :P I meant that the gas in the higher atmosphere of a terraformed Mars would have a higher density than the gas in the higher atmosphere of earth. at ground level they would have the same pressure.

sorry 4 my english

as for the book.. well sorry I just don't like science fiction. it's just a personal preference, sry.
 
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  • #66
Nikitin said:
that was not what I meant :P I meant that the gas in the higher atmosphere of a terraformed Mars would have a higher density than the gas in the higher atmosphere of earth. at ground level they would have the same pressure.

In post 43 I said

I am unsure about how bad the radiation would be on Mars if there were a thick atmosphere, the atmosphere on Mars would have to be much thicker than that of Earth's to account for the face that Mars has a lower gravity. This means an equal amount of atmosphere would not cause the same pressure obviously necessary for life.

Leading on from this the atmosphere engineering of Mars could have much harder problems to solve, if the atmosphere needs to be 3x thicker to provide the same pressure then we may have problems with the amount of radiation absorbed. In addition martian weather systems could be drastically different from Earth's if the atmosphere was much denser, how this would effect the ecology would have to be carefully considered.

I am aware that we would need three times as much gas to produce the same pressure at ground level but you said in post 56

Anyway, I don't think the molar density of the air close to the surface of a completely terraformed Mars would be particularly higher than on earth.

There is a difference between air pressure and molar density. On Mars we would need 3 times as much atmosphere for the same pressure. You post at 56 suggested that this would not change the molar density at ground level, I'm interested to know how you came to this conclusion?

I may be wrong but if we have a column of air in a tube on Earth and exactly the same amount of air in a tube on Mars there will be more pressure at the bottom of the Earth tube (because gravity is higher). This is the same as if I had a 100kg weight on my head on Earth it would be putting 3x more pressure on my head than on Mars. To compensate for this lack of pressure 3x as much atmosphere is needed but would this not create a higher molar density on Mars? I would suggest yes (which would have dramatic effects on life) unless the atmosphere on Mars was spread out 3x further from the planet. I'd be interested to know if I am right or wrong here.
 
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  • #67
ryan_m_b said:
Why would this be?

I think the supposition is based on the differential equation for pressure of column of gas as:

dP/dr = density*G*M/r^2

Then, further assuming temperature and composition are constant, density is proportional to pressure. Then, for mars, GM/r^2 at surface (surface gravitational acceleration) is lower than for earth; thus at given pressure, dp/dr will be lower than for earth. Thus, if pressure at surface matches earth, pressure and density above surface will higher (slower rate of decline).

Big flaw: even if you assume T and P are the same on the surface of Mars as for earth, there is absolutely no reason to believe that T as a function of altitude will be the same, let alone constant. Further, one expects composition to vary with altitude. However, I wouldn't be surprised of the broad conclusion were true: that matching P and T at the surface will lead to higher density at given altitudes compared to earth.

(To clarify the more complex realistic case, P = density * specific gas constant * T. Realistically, both T and specific gas constant (which is dependent on composition) vary with altitude).
 
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  • #68
PAllen said:
I think the supposition is based on the differential equation for pressure of column of gas as:

dP/dr = density*G*M/r^2

Then, further assuming temperature and composition are constant, density is proportional to pressure. Then, for mars, GM/r^2 at surface (surface gravitational acceleration) is lower than for earth; thus at given pressure, dp/dr will be lower than for earth. Thus, if pressure at surface matches earth, pressure and density above surface will higher (slower rate of decline).

Big flaw: even if you assume T and P are the same on the surface of Mars as for earth, there is absolutely no reason to believe that T as a function of altitude will be the same, let alone constant. Further, one expects composition to vary with altitude. However, I wouldn't be surprised of the broad conclusion were true: that matching P and T at the surface will lead to higher density at given altitudes compared to earth.

(To clarify the more complex realistic case, P = density *specific gas constant * T. Realistically, both T and specific gas constant (which is dependent on composition) vary with altitude).

So I would take that to mean in theory it could be the same as Earth but in practice no? The only thing I am struggling with is why there may be higher density at given altitudes but not at ground level?
 
  • #69
ryan_m_b said:
So I would take that to mean in theory it could be the same as Earth but in practice no? The only thing I am struggling with is why there may be higher density at given altitudes but not at ground level?

Under the simplistic assumption of constant temperature and composition you have (from the equations I gave before):

dP/dr = P * a / b

where b = (specific gas constant * T), and a = acceleration of gravity. So if you match P at the surface of Mars with P at Earth's surface, dP/dr will be smaller because 'a' is smaller. This means the rate of decline of pressure with altitude will be smaller than earth. Under the same simplistic assumptions, the density will also decline slower with altitude than Earth (and will match at the surface).

While constant composition and temperature are absurd, I suspect the broad conclusion would remain true. However, while ideal gas theory is physics, so I know a bit, the way temperature and composition would realistically change with altitude in the two cases (one hypothetical) is atmospheric science about which I know next to nothing.
 
  • #70
ryan_m_b said:
In post 43 I said
I am aware that we would need three times as much gas to produce the same pressure at ground level but you said in post 56
There is a difference between air pressure and molar density. On Mars we would need 3 times as much atmosphere for the same pressure. You post at 56 suggested that this would not change the molar density at ground level, I'm interested to know how you came to this conclusion?

I may be wrong but if we have a column of air in a tube on Earth and exactly the same amount of air in a tube on Mars there will be more pressure at the bottom of the Earth tube (because gravity is higher). This is the same as if I had a 100kg weight on my head on Earth it would be putting 3x more pressure on my head than on Mars. To compensate for this lack of pressure 3x as much atmosphere is needed but would this not create a higher molar density on Mars? I would suggest yes (which would have dramatic effects on life) unless the atmosphere on Mars was spread out 3x further from the planet. I'd be interested to know if I am right or wrong here.

Hmm, well, at ground level the pressure and thus the molar density (assuming 99% of the air is nitrogen/oxygen) would be the circa same (molar density is dependant on pressure n temperature) as on Earth.

However, to get this identical ground level pressure on a low-gravity planet you'd need to have something compensating for the gravity - and that is the air above the ground-level air. The air above would be pushing the ground level air down - and we'd need more of it on Mars than on Earth to compensate for the weak Martian gravity.

EDIT: And yeh, while I'm making quite the assumptions, ignoring that the temperature decline on the Martian atmosphere will be quite different than that on earth, I don't see why my assumption is necessarily false, though. And I wouldn't mind at all if people would prove me wrong :D
 
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<h2>What is terraforming?</h2><p>Terraforming is the process of deliberately altering the environment of a planet or other astronomical body to make it more similar to Earth, in order to make it habitable for humans.</p><h2>Why is Mars a potential candidate for terraforming?</h2><p>Mars is the most Earth-like planet in our solar system, with a similar day length, seasons, and presence of water. It also has a thin atmosphere and evidence of past habitability, making it a potential candidate for terraforming.</p><h2>What are the main challenges of terraforming Mars?</h2><p>The main challenges of terraforming Mars include its low temperature, low air pressure, and high levels of radiation. These factors would need to be addressed in order to make the planet habitable for humans.</p><h2>How can the temperature on Mars be increased?</h2><p>The temperature on Mars can be increased through various methods, such as releasing greenhouse gases into the atmosphere to trap heat, building large mirrors to reflect sunlight onto the surface, and using nuclear reactors to generate heat.</p><h2>What are the potential solutions for increasing air pressure and reducing radiation on Mars?</h2><p>Potential solutions for increasing air pressure on Mars include releasing gases from the planet's crust or importing them from other sources. To reduce radiation, habitats could be built underground or with thick shielding materials, and a magnetic shield could be created around the planet to deflect harmful solar wind.</p>

What is terraforming?

Terraforming is the process of deliberately altering the environment of a planet or other astronomical body to make it more similar to Earth, in order to make it habitable for humans.

Why is Mars a potential candidate for terraforming?

Mars is the most Earth-like planet in our solar system, with a similar day length, seasons, and presence of water. It also has a thin atmosphere and evidence of past habitability, making it a potential candidate for terraforming.

What are the main challenges of terraforming Mars?

The main challenges of terraforming Mars include its low temperature, low air pressure, and high levels of radiation. These factors would need to be addressed in order to make the planet habitable for humans.

How can the temperature on Mars be increased?

The temperature on Mars can be increased through various methods, such as releasing greenhouse gases into the atmosphere to trap heat, building large mirrors to reflect sunlight onto the surface, and using nuclear reactors to generate heat.

What are the potential solutions for increasing air pressure and reducing radiation on Mars?

Potential solutions for increasing air pressure on Mars include releasing gases from the planet's crust or importing them from other sources. To reduce radiation, habitats could be built underground or with thick shielding materials, and a magnetic shield could be created around the planet to deflect harmful solar wind.

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