breathable

[K^2]

But the gravity of mars is not enoght either, so even if we solve all long term issues with oxygen, we still have the long term issues due gravity.. unless we use genetic engineering.

Increasing the pressure is not efficient either, because mars would lose higher amount of atmosphere by day, more than the amount produced.

We might be able to increase pressure by using heavier buffer gases. Since oxygen's partial pressure would still be just enough for breathing, it wouldn't escape any faster than without a buffer gas, but total pressure would be higher, and oxygen would be diluted. Both are very good things.

Unfortunately, it's hard to come up with a good, heavy buffer that is easy to get in planet-wide quantities. And I mean even in comparison to such a gargantuan task as simply dumping enough CO2 or water vapor into atmo to offset the pressure.

As for gravity itself, I don't think it's going to be a huge problem. It's low, but it's within adaptable range. With the right exercise regimen, it should be possible to live on Mars long-term without ill effects to health.

This leaves the next big problem. Lack of the mag-field. Re-magnetizing Mars is going to be one of the pre-requisites to making it livable. Not only is it bad enough that it's going to be irradiated, but radiation is going to be breaking down water vapor, and the planet will keep losing hydrogen, like it did in the past.

[TheDarkStar]

How much energy would it take to re-magnetize Mars?

[K^2]

Energy density of Earth's magnetic field is about 0.5-1 mPa. So on the order of 10¹⁶J to re-magnetize Mars. That's a "few" years of Earth's total energy consumption. Keeping in mind that I did a very rough estimate for total energy which could be more than an order of magnitude off. So we can be talking weeks or decades instead of years.

But these are comprehensible amounts of energy even now.

[Newt]

How much energy would it take to re-magnetize Mars?

It is not just a problem of 'remagnetizing' Mars--part of the reason that Earth/Mercury/Jupiter have strong magnetic feilds is their liquid cores. Mars would not really work the same way, that is why it does not have a magnetic feild of not at this time.

This does not mean you could not do it, of course, and already the assumptions of this thread put us well into science fiction. But I am not sure how practical it would be to simply run energy into it (I have not studied planetary magnetic feilds much, so take my undeveloped opinion with skeptecism).

[K^2]

Well, you need something to sustain the field. I'm guessing, it would involve a planet-wide network of superconductors. But you will still need that energy to energize the magnets.

[vger]

There's really no point to terraforming Mars. Even with breathable air, the ground will be very bad for us. Mars soil is full of silicates, and you do NOT want to breathe it. Even letting it get in through your front door is begging to have your lungs turned into swiss cheese.

[K^2]

That would change pretty fast once it starts raining.

[peadar1987]

This leaves the next big problem. Lack of the mag-field. Re-magnetizing Mars is going to be one of the pre-requisites to making it livable. Not only is it bad enough that it's going to be irradiated, but radiation is going to be breaking down water vapor, and the planet will keep losing hydrogen, like it did in the past.

At surface level you'd be pretty well-shielded from radiation by the mass of the atmosphere above you. Losing hydrogen is more of a problem.

[-Velocity-]

This leaves the next big problem. Lack of the mag-field. Re-magnetizing Mars is going to be one of the pre-requisites to making it livable. Not only is it bad enough that it's going to be irradiated, but radiation is going to be breaking down water vapor, and the planet will keep losing hydrogen, like it did in the past.

No, I don't think that magnetizing Mars is necessarily a requirement unless you want a Martian biosphere that can survive hundred million year absences of intelligent tenants. If you have the technology to terraform Mars, you probably also have the technology to truck in comets and bring the volatiles down to the surface (perhaps with space elevators, as Mars is a great place to build them). And even if we don't have the ability to keep Mars' atmosphere topped off, terraforming it still leads to at least something like 50 million years of habitability. That is a tremendously long time.

Again, if you think that a magnetic field is somehow required for a biosphere, please explain how Earth life survives (with no detectable extinctions) magnetic reversals when the magnetosphere largely disappears for thousands of years. A magnetic field is NOT required for radiation shielding of the surface- not if the atmosphere is thick enough (how thick exactly? I don't know). A magnetic field is most important for shielding the upper atmosphere.

Also consider that atmospheric pressure is proportional to the weight of the air column above you. To get 1 atm on Mars, you need an air column with 1/0.37 = 2.7 times more air mass. So there would be 2.7 times more atmosphere protecting you on Mars at 1 atm than on Earth at 1 atm. It might even be the case that Mars at 1 atm with no magnetic field has lower levels of radiation than Earth at 1 atm WITH a magnetic field.

I know I've read about Martian surface radiation with no magnetic field but a thick atmosphere somewhere. I'll try to dig up some sources.

Edited May 4, 2015 by |Velocity|

[-Velocity-]

Ok, so far using Google Scholar I can find precious little information on the subject. I can't really afford to spend any more time on it. I found a paper from 1968, for example, that supposedly refutes the idea that the last geomagnetic reversal caused a minor extinction, or that geomagnetic reversals would result in an extinction. But it's from 1968. I found some more papers discussing small radioactive isotope spikes in the geological record coinciding with field reversals. I also found a "paper" on generating a magnetic field around Mars with a single turn copper coil, and the requirements of such a coil. I say "paper" because calculating such a thing is a simple exercise best left to undergraduate Emag students, so it's kinda generous to call it a "paper". Anyway, I simply couldn't find any papers on what the surface radiation would be like for Mars with a thick atmosphere but no magnetic field. You'd certainly have higher amounts of radioactive isotopes raining down (the cosmic rays can transmute elements into radioactive isotopes, that's how we get carbon 14, for example), but I don't know how much radiation those elements would emit, or how they would compare to the secondary particle showers cosmic rays generate, and how much of the particle showers would make it to the surface, and so on. I've been assuming that the cosmic ray generated radioactive isotopes would be negligible to the secondary particle showers, but I suppose with a thick enough atmosphere, there must be a point where the radioactive isotopes become a larger fraction of the radiation you get exposed to- and for all I know, even Earth's atmosphere is thick enough for that.

Edited May 4, 2015 by |Velocity|

[AngelLestat]

This discussion is deriving in something more complex as full terraforming.

Of course if we wanna produce that amount of oxygen we would need the help of plants.

For that we still need great amounts of water and nitrogen(that can be your buffer), plus start with a heavy greenhouse effect using methane or other components.

There are many methods in literature of how it may be possible to achieve this with the low energy comsumption (which is still very far from our reach).

But... mars gravity is still a problem.

Our body is designed to 1g, no animal in the earth was exposed to any different force field over its evolution.

Experiments on animal reproduction in the ISS are all discouraging, death or fails are a common outcome.

This may be even worst on mammals due how sensitive the method is, but more data is needed.

Bones fall prey to a kind of space-flight-induced osteoporosis. And because 99 percent of our body’s calcium is stored in the skeleton, as it wastes away, that calcium finds its way into the bloodstream, causing yet more problems from constipation to renal stones to psychotic depression.

All muscles including the heart had similar deterioration.

Red blood cell counts also fall, plus other effects mentioned in the links.

http://www.medicaldaily.com/life-mars-how-caustic-dust-atmospheric-pressure-and-low-gravity-may-alter-human-body-320170

http://www.wired.com/2014/02/happens-body-mars/

How much would affect us in comparison to the ISS, hard to know, maybe we can stand more than 3 to 10 times the safety exposure time we accomplish in the ISS, this gives us from 3 to 10 years. But this for sure would be harder for children development or reproduction.

We can use an spinning habitat with a concave shape like the one I draw for the moon (but with different shape adjusted to mars gravity), that might help but increase the complexity of the colonization.

[peadar1987]

The ISS is zero-gravity, Mars is 0.4g, they are completely incomparable. We simply don't know what would happen to the human body in 0.4g, and any statements to the contrary are just conjecture.

[AngelLestat]

0.38g, and yes we know.. we cant said with enoght certainty, but we can aproximate a number.

Medics know very well how the body works. They can predict many things, some are mentioned in the links.

[peadar1987]

0.38g, and yes we know.. we cant said with enoght certainty, but we can aproximate a number.

Medics know very well how the body works. They can predict many things, some are mentioned in the links.

One of those links gets its data from the other, so it's really only one link. And the research it cites is all based on zero-G research. We can say that there will probably be some detrimental effects to living in 0.4g. We have pretty much no idea how severe those effects will be, aside from "worse than earth, better than the ISS". Your figure of "3-10 times longer" is a complete fabrication. The one published paper I found on the subject: http://www.sciencedirect.com/science/article/pii/S0094576514000721 suggests that for bone density at least, even 1/6 g with a moderate programme of exercise is enough to mitigate many of the harmful effects.

[K^2]

How much would affect us in comparison to the ISS, hard to know, maybe we can stand more than 3 to 10 times the safety exposure time we accomplish in the ISS, this gives us from 3 to 10 years.

I'm going to say it's closer to 100-300 times, allowing normal life on Mars' surface.

Proof by fabrication. It's fun for everyone! Also, completely useless.

Available hypogravity research is very limited, but what we have points to even small amount of persistent gravity making a huge difference. We will know a lot more once the centrifuge module is built on ISS, but right now, there is no reason to think that Mars' gravity is insufficient. It might be. But it's total speculation.

[AngelLestat]

so any branch of science may be allow it to make predictions but not medicine? They did not said the exact amount of health deterioration that it will get, they just said that it will be important.

But it seems that you think the gravity problem is a exponential one.. with an asymptote that increase a lot when it reach zero.

The function in many of the consequences is linear.

For example muscle, bone and heart deterioration; what matters most is the amout of effort you do, if you support 80kg at all moment you are fine.. if you support the half, you will have a big muscle deterioration, only 20 kg, more... and 0kg is like do nothing.. be lazy.. Is not 1000 times worst.. is linear.

The medics know very well the effects of low gravity, also know very well the risks of each one of those and many other deteriorations.

http://www.sciencedirect.com/science...94576514000721

it does not said how much exercise mitigate that.. it said something about 9.8% and P>0.01.. but not idea what those numbers means (maybe something with the normal distribution curve)

Of course training helps, because you are breaking muscle fibers, then new ones grow. But in the ISS astronauts always do exercise, but never is enoght.

[K^2]

but not idea what those numbers means

And you don't think it's a problem? I'm yet to see a paper that backs up your claims.

[prophet_01]

Wouldn't a mostly o2 composed atmosphere be a significant fire hazard? I'm not the best when it comes to chemistry, but this should be quite dangerous if we are talking about colonisation efforts on a bigger scale. (Edit: just read the whole threat, sry for repeating)

Also is it possible trap atmosphere inside a crater if you build walls on top of the natural crater walls? The low gravity should allow quite high walls. Of course you would have to constantly produce more atmosphere in order to replace the losses, but if we use a gas with rather high density I think it might be worth a look at. I wonder how tall a barrier would need to be in order to trap any reasonable levels of atmosphere. Sadly I don't have any idea where to start with a calculation

Edited May 5, 2015 by prophet_01

[peadar1987]

so any branch of science may be allow it to make predictions but not medicine? They did not said the exact amount of health deterioration that it will get, they just said that it will be important.

But it seems that you think the gravity problem is a exponential one.. with an asymptote that increase a lot when it reach zero.

The thing is that the people you have cited are not medical researchers, they are popular science writers. Medical researchers are of course allowed to make predictions based on actual data and empirical evidence. I am an engineering researcher, and no predictions I make have any weight unless I can back them up with maths or experimental data.

The function in many of the consequences is linear.

We don't know this. We have two data points, 0g and 1g, and nothing in between. We have no idea what the line is going to do in between.

For example muscle, bone and heart deterioration; what matters most is the amout of effort you do, if you support 80kg at all moment you are fine.. if you support the half, you will have a big muscle deterioration, only 20 kg, more... and 0kg is like do nothing.. be lazy.. Is not 1000 times worst.. is linear.

The medics know very well the effects of low gravity, also know very well the risks of each one of those and many other deteriorations.

Medics know the effects of zero gravity. They don't know the effects of low gravity.

it does not said how much exercise mitigate that.. it said something about 9.8% and P>0.01.. but not idea what those numbers means (maybe something with the normal distribution curve)

Of course training helps, because you are breaking muscle fibers, then new ones grow. But in the ISS astronauts always do exercise, but never is enoght.

And the ISS is not Mars, it is a microgravity environment.

The paper's results say, more or less, that when the rats were left to their own devices in lunar gravity conditions, they lost 9.8% of their bone density. When they ran for 32-50 minutes a day, bone density actually increased. The P values are to do with the statistical significance of the results. Basically the lower the P values, the more likely the hypothesis is true, and the less likely that the results are down to some statistical anomaly.

[AngelLestat]

And you don't think it's a problem? I'm yet to see a paper that backs up your claims.

I would like to know with certainty, sure. But we are discussing between us, not making a claim to the world, so estimations on base of the things we know are allow it.

The thing is that the people you have cited are not medical researchers, they are popular science writers. Medical researchers are of course allowed to make predictions based on actual data and empirical evidence. I am an engineering researcher, and no predictions I make have any weight unless I can back them up with maths or experimental data.

Is not different from the things mentioned here:

http://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body#Loss_of_bone_and_muscle_mass

Or here

http://www.mainsgate.com/spacebio/general/resources/humansandspacebio.pdf (math and experimental data)

http://www.nsbri.org/DISCOVERIES-FOR-SPACE-and-EARTH/The-Body-in-Space/

http://www.racetomars.ca/mars/article_effects.jsp

None of those articles makes claim about any level of microgravity, they just talk about the problem of the body under lower levels of gravity than earth.

We don't know this. We have two data points, 0g and 1g, and nothing in between. We have no idea what the line is going to do in between.

Medics know the effects of zero gravity. They don't know the effects of low gravity.

We have more than that. As I said.. muscle and bone deterioration or improvement depends on the level of effort made.

If you go to the gym and you work up very hard, you will gain bone and muscle mass, then if you stop that your bones and muscle deteriorate, if you stay in bed doing nothing, the deterioration is even worse (that is why nasa study this with people resting in beds). The effect is linear, all this result in dangerous calcification of soft tissues and potential kidney stone formation plus possible bone brakes and heart problems in case you want to counter this with hard workout.

The paper's results say, more or less, that when the rats were left to their own devices in lunar gravity conditions, they lost 9.8% of their bone density. When they ran for 32-50 minutes a day, bone density actually increased. The P values are to do with the statistical significance of the results. Basically the lower the P values, the more likely the hypothesis is true, and the less likely that the results are down to some statistical anomaly.

But how much increased? It does not said.. if the control test is 9.8%, it should said with exercise they lost only 5% (just to said a number).

------------------------------------------------------

Also in case nobody notice.. My estimation is base on the safe margins levels base on astronauts on the iss that go back to earth, so my estimation times are applied for people which comeback to earth.

I am not sure what is the safe level if your plan is to remain in mars your whole life. Also we dont know the effects on our organs or child developement.

So what I said is: Is a problem impossible to solve? Not..

You can go to mars in gravity wheels and adjust the speed gradually when they go back to reduce the recovery time.

We can have gravity concave habitats there in mars, as places to go exercise all days as people do in the ISS, that is more accurate than a heavy suit.

Edited May 5, 2015 by AngelLestat

[peadar1987]

I would like to know with certainty, sure. But we are discussing between us, not making a claim to the world, so estimations on base of the things we know are allow it.

Is not different from the things mentioned here:

http://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body#Loss_of_bone_and_muscle_mass

Or here

http://www.mainsgate.com/spacebio/general/resources/humansandspacebio.pdf (math and experimental data)

http://www.nsbri.org/DISCOVERIES-FOR-SPACE-and-EARTH/The-Body-in-Space/

http://www.racetomars.ca/mars/article_effects.jsp

None of those articles makes claim about any level of microgravity, they just talk about the problem of the body under lower levels of gravity than earth.

You seem to be misunderstanding what microgravity means. It is essentially synonymous with zero-g. Every one of those articles you linked only talks about microgravity, none of them about Martian, or even lunar gravity.

We have more than that. As I said.. muscle and bone deterioration or improvement depends on the level of effort made.

If you go to the gym and you work up very hard, you will gain bone and muscle mass, then if you stop that your bones and muscle deteriorate, if you stay in bed doing nothing, the deterioration is even worse (that is why nasa study this with people resting in beds). The effect is linear, all this result in dangerous calcification of soft tissues and potential kidney stone formation plus possible bone brakes and heart problems in case you want to counter this with hard workout.

The effect isn't linear. Someone who does twice as much exercise as me isn't going to have twice the bone density or muscle mass, and somebody who does half as much isn't going to have half. You're looking at it in a very simplistic way. Even if this were true, someone who was reasonably active in 0.4g would be doing far more work than a sedentary office worker on earth, and giant centrifuges would be a completely unnecessary complication.

But how much increased? It does not said.. if the control test is 9.8%, it should said with exercise they lost only 5% (just to said a number).

The rest of the article is behind a paywall, the exact data isn't in the abstract. If the effects were linear, as you claimed, lunar gravity, which is 1/6 that of earth's, would result in the bone density dropping by 83%. Even the abstract is enough to show that this is not the case.

[AngelLestat]

first point, you are right. But in prrevious quick read that I did, in some place mention other cases for the bone and muscle case, now I cant find them.

I did some graphics so you understand what I mean by linear.

This is my estimation without (exercise to avoid confusion), in case we add execise then I guess it may be "similar" function shape but adding a 20% to 30% muscle mass.

From your comments, I am assuming that you think it will be similar to this:

All the things we know about muscles disagree with this assumption.

You mention that someone who does twice as exercise as you it will not have twice muscle increase, but it depends, if that guy is at equal muscle mass than you when it does, then yes, is possible. This happens because you are not taking the time into the equation.

If we enter the time in the first graph it will give us a 3D function with a new cordenates showing how the graph change with time.

That is where appears a concave shape in the function.

Of course this takes only into account musscle increase/decrease, there are other factors that I am ignoring, at certain point the heart or arteries would not be able to stand high gravity levels, the same may happen with low gravity. Genetics limits or different organs issues may have something to said.

You can mitigate the problem with exercise, maybe 2 hours a day, but that is a time resource than mars people needs to comply, is a drawback. Maybe if they dont plan to return to earth, with the help of some medicines they will be fine. But we still have the reproduction and children development issues, there is not enoght evidence but the concerns are many.