Magnetizing Mars - Creation of a Martian Magnetosphere

BobL · 2005-03-12 21:56:22

http://www.islandone.org/Settlements/Ma … l]Magnetic Shielding

I believe that the creation of a martian magnetosphere is essential to any long term terraformation plans. Doing so would not only help to prevent the long, slow leak of atmosphere from Mars, but it would also help protect the surface from harmful radiation, which even with earth atmospheric pressure and temperature would probably still reach unnacceptable levels during periods of intense solar activity. Utilizing the concept outlined in the aforementioned paper (link), I believe that it would be technically possible to employ this concept on a massive scale, effectively creating a martian magnetosphere. Any thoughts? Anyone care to try number crunching to see what it would take to give mars a magnetic field compareable to Earth's?

chat · 2005-03-13 06:07:51

Hi BobL

If we hope to have any life form survive the radiation on the surface, even bacteria on a wet warmer mars would be pushed to survive.

The power requirements

A huge globe encircling coil will do the trick, probably 4 50 mw reactors to power it.
A couple of reactors for backup as no down time can be allowed.

Also the power requirements for building such a thing are staggering.

Let alone the enormous power required to get mars to any % of being teraformed.
At least a billion mw/year/200 years (very conservative estimate)

Much easier to put up a few west Edmonton malls on mars under glass that needs no teraforming or magnetic field.
You will need 1- 10 mw reactor, and 1 backup unit.
Then expand as needed as the city grows.

I don't want to sound to negative about teraforming Mars, but the numbers don't look good for anything else but domed cities.
Then again a few well placed impacts on mars could alter the power requirements drasticly, but with equally drastic effects.

Dook · 2005-03-13 07:28:26

Rather than attempting to shield the whole planet why not put magnetic field generators in a stationary orbit above population centers?

BobL · 2005-03-13 09:33:16

Reducing the radiation levels across Mars brings Mars one step closer to being a hospitable world. I agree that at first any kind of human settlement on mars will have to be contained in domed structures, but as time progresses and perhaps other terraformation techniques are developed, it may become more feasible to start terraforming the whole of the planet. If that happens, then the existence of a magnetosphere on mars would be essential to any planetwide terraformation attempts. Sure it would take massive energy requirements to build such a device, but it would allow for life to take hold on a much larger scale (and thus accelerate the terraformation process itself) on mars should martians decide to attempt to terraform the planet. With regards to having orbital magnetic field generators, I doubt they would be effective because of the distance required for stationary orbit and the fact that any magnetic field produced by these sattelites would not actually enclose the populated areas they were intended to protect.

chat · 2005-03-13 13:23:21

Dook,

Good side bad side to placing a orbital system.
Down side is a tiny meteorite can destroy it, servicing it will also be very tough.

Plus side is a space based system will require less power, maybe only 100mw.
Down side a 100 mw reactor in orbit, and creating one, and the chance of it de-orbiting with all that nuclear material.

BobL,

A few feet of Martian soil on top of a structure offers the same protection as a planet wide magnet field.

Power requirements (a good shovel).

I also agree with the mars colonist scenario.
If Martians take up home first, then teraforming will require so much power that the colonists decide to put the power to better uses.

Only hope for a teraformed mars is to do it before they take up residence.
The power requirements are so high to teraform mars that quite a few impactors will be needed to jolt mars into a new climatic equilibrium.
At this point in our technology that will require 100s of billions of $ and hundreds of years to get the asteroids and comets to mars.

Or de orbit phobos onto a pole , and hope for the best.
Hope that the titanic impact that occurs releases enough co2 and h20 to alter mars, and the storm of dust and awful weather doesn't last for 100s of years.
Afterwards you might simply end up with a hellish mars for 2 years that settles pretty much back to the way it was as all the elements freeze back to the poles.

Dook · 2005-03-13 14:17:28

Dook,
Good side bad side to placing a orbital system.
Down side is a tiny meteorite can destroy it, servicing it will also be very tough.
Plus side is a space based system will require less power, maybe only 100mw.
Down side a 100 mw reactor in orbit, and creating one, and the chance of it de-orbiting with all that nuclear material.

I'm just not that worried about tiny meteorites. I think the chances are better at winning the lottery twice than having a meteorite hit and disable a satellite.

Have any of our satellites ever been hit?

We would need to build it so it's highly automated so human maintenance is at a minimum.

De-orbit? How is that going to happen? If it's placed in a synchronous orbit it stays there forever.

Plus mars will need nuclear reactors at some point anyway so whats the problem with leaving one in space far above it?

Regardless the sandbags are still the easiest solution.

RobS · 2005-03-13 14:45:39

I'm still not convinced any such magnetic field generator is needed. First of all, Mars won't lose even one percent of its atmosphere every ten million years; the loss rate is very slow (otherwise the dominant ingredient in its atmosphere right now would be a vacuum!). Second of all, even now the Martian atmosphere provides enough protection against solar radiation except in solar storm times, and even then the level of radiation reaching the surface won't kill plants and animals; it would just raise the human cancer level. At least I think that's the situation.

According to the *Case for Mars,* page 118-19, during a severe solar storm, the astronauts en route to Mars, outside the storm shelter but in the Hab, would receive 38 rems; inside the storm shelter (38 gm/cm2 of shielding) they'd receive 8 rems; on the surface of Mars in a spacesuit during the same storm, 10 rems; inside the hab on the surface during the same storm, 3 rems. The shielding of 38 gm/cm2 corresponds to 380 kg/m2 and the Martian atmosphere's mass is about 200 kg/m2. If you even partially terraformed the place the atmosphere would shield the surface plenty from solar radiation.

-- RobS

chat · 2005-03-13 16:45:55

Dook,

No real problem with leaving a reactor in space that might plummet to the ground on mars.
When it impacts it will add to the radioactivity for a few 1000 years.

Even the shuttle going to space for a few weeks gets hit by micro meteorites.
A few years in space is a guarantee for a impact that would disable it.
Most satellites are lost to solar flares though, in earth orbit these flares are minor compared to mars orbit.

I bet the energy needs are less to greenhouse glass all of mars vs terarofming it, or adding a manmade magnetic field that is secure and permanent.

RobS,

For day to day life for humans that can go indoors life will be great on mars with only a thicker atmosphere.

Plants, bacteria, liken etc can't take the constant gamma ray Xray etc bombardment from everywhere and the occasional charged particle bombardment from solar flares.
At best the mutation rate would be out of control, and probably beyond the point of species recognition for propagation.

The type of radiation on mars will be the problem not the quantity.

It might be a better idea to have local magnetic fields for city and land area that combats both problems.

It fits better with a slow buildup of mars anyway to have things start small and expand safely.

Shaun Barrett · 2005-03-13 19:04:03

Sometimes at New Mars I feel like we're going round in circles. It often seems that issues can arise, be discussed, have reasonable conclusions reached about them ... and then the same issues arise again as if the've never been discussed! :bars:
I believe RobS is correct, as I tried to point out to Chat just the other day at "Mars needs Nitrogen":-

Hi Chat:-
[QUOTE from Chat:-
But on mars the problem is not just UV at 50X earth levels, but gama rays, x rays, cosmic rays, charged particles etc that mars blocks little to none. UNQUOTE.]
The question we're dealing with relates to the environment on Mars after full terraforming has been achieved. Full terraforming, in most people's minds, involves the creation of an atmosphere which allows humans to roam freely on the surface without the need for a pressure suit or respirator.
Obviously, the ideal situation would be to create an atmosphere just like Earth's: 1013 millibars at sea-level, consisting of 78% N2, 21% O2, 0.9% Argon, 0.03% CO2, plus trace gases.
However, there's no guarantee that the volatiles we would need to do this are available in sufficient quantity. As a result, it appears most people would be satisfied if we could create 'half an atmosphere', which is to say a surface pressure of about 500 millibars.
To provide the same partial pressure of oxygen we enjoy here on Earth, i.e. roughly 210 millibars, it's clear from the figures that we need to enrich our 500 millibar atmosphere to 40% O2. So, we end up with air which is about 40% O2 and 60% N2, assuming we ever find that much nitrogen somewhere on Mars! Again, this brings us back to the fabled nitrate beds and the denitrifying bacteria Earthfirst has been talking to Clark about.
But the point I've been trying to make is to compare this new 500 millibar O2/N2 atmosphere with the closest equivalent we have here on Earth, in an attempt to show that the environment on a fully terraformed Mars is, in fact, quite liveable for not only plants but humans. This is why I searched for inhabited regions of Earth at an altitude of 5600 metres, which gives us broadly the same ambient pressure as we'd have on our new Mars.
And, sure enough, I discovered that 7000 people live at La Rinconada in Peru at an altitude of 5100 metres, where the pressure is about 530 millibars. Interestingly, the partial pressure of O2 at this altitude must be little more than 110 millibars, only half of the oxygen partial pressure our new Martians will experience at sea-level on Mars. And yet people have lived and reproduced under these adverse conditions in La Rinconada for 40 years - a testament to the adaptability of our species and perhaps a portent of how humans may change very quickly to adapt to life on Mars.
When we've created the oxygen-rich atmosphere we're talking about, an ozone layer will form in the Martian stratosphere and reduce UV levels to no more than those experienced on Earth - almost certainly less, in fact, because of the O2 enrichment I mentioned, and because Mars is roughly 75 million kilometres further from the Sun (insolation being only 43% of that at Earth's distance).
Gamma Rays and X-Rays are electromagnetic radiation, just like visible light. Such radiation is unaffected by magnetic fields. This means the lack of a global magnetic field on Mars makes no difference to the influx of this radiation - and in fact, our terraformed Martian surface will get no more of it than La Rinconada gets.
Galactic Cosmic Rays are essentially atomic nuclei travelling at relativistic velocities. The lower energy Cosmic Rays are affected by the Sun's and Earth's magnetic fields and are largely stopped by a blanketing atmosphere. The heavier high-speed nuclei, while deflected by our magnetic field, still reach Earth's atmosphere. On the way through the atmosphere, many collide with atoms and produce a cascade of secondary particles, attenuating their penetrating power. But still, many reach the surface and this hasn't made life untenable on Earth.
The Sun's magnetic field (and possibly Mars' scattered, 'fossil', crustal magnetic field) plus the 500 millibar atmosphere we propose to create, will stop all but the higher-energy Cosmic Rays. These will reach the surface of Mars in greater numbers than they do here but very probably not in show-stopping numbers.
Experiments show that the number of Cosmic Rays penetrating Earth's atmosphere at the altitude of La Rinconada, is roughly double the number reaching sea-level. The number of high-energy Cosmic Rays reaching sea-level on a terraformed Mars is yet to be calculated, as far as I know, but I suspect it won't be dangerously higher than at La Rinconada.
We should remember that roughly every 250,000 years Earth's magnetic field reduces to zero as it undergoes a polarity change. This has happened countless times throughout Earth's history and yet there's no evidence that this periodic 'lowering of the shields' has had any detrimental effect on terrestrial life.
This is a telling indicator that Earth's atmosphere is much more important in protecting life on the surface from both Galactic Cosmic Rays and the Solar Wind particles than its magnetic field.
I think it's inevitable that there will be a generally higher level of ionizing radiation on a terraformed Mars but I don't believe it will be anywhere near high enough to affect the viability of surface life. One consequence might be accelerated evolution through the agency of more frequent mutations - and this in itself will probably lead to the evolution of more radiation-hardened organisms, given time.
I certainly don't agree with you, Chat, that plant life will be unable to survive on the surface of our new world; I think your analysis is way too pessimistic.

And now here we have Chat rehashing exactly the same perceived problems as though our exchange never took place!
As RobS has pointed out again, the fact is that a dense atmosphere is much more important than a magnetic field when it comes to radiation protection. Mars' lack of a global field is not a showstopper for people, who spend most of their time indoors anyway, and will certainly not prevent plants thriving on the surface. As I said, at worst there might be a slightly higher background radiation level due to high-energy cosmic rays .. that's all.

Excuse me getting irritated here but I like to think of a discussion as a progressive thing - whereby a general overview of the subject under discussion can evolve and develop. In other words, so that we can establish what is realistic and dismiss anything we decide is unrealistic.
It becomes frustrating when the same unrealistic scenarios are introduced into the conversation over and over, as if we've learned nothing from our own research and exchange of ideas.

Incidentally, the idea of domed habitats on Mars may indeed be more achievable than terraforming the whole planet, but domes have been discussed at length too. When we talked about domes, it became apparent that the enormous pressure differential between the inside and the outside was not fully appreciated by everyone involved at the time. And, on current form, it seems a fair bet that some of us will have forgotten the lessons learned in that department, as well.
Creating domes large enough to contain even modest settlements was found to require quite staggering feats of engineering due to pressures of some 5 tonnes/square metre trying to lift the domes off the ground! (Even the prospect of using half-buried spherical or 'truncated-spherical' membranes to eliminate the 'lift factor' required massive earthworks to shift hundreds of tonnes of regolith.)
These problems would be solved if we thickened the Martian CO2 atmosphere to reduce the pressure differential to almost zero, thus allowing domes of virtually unlimited size to be produced with ease. (See Dr. Zubrin's comments to this effect in "The Case For Mars".)

One way or another, any serious settlement of Mars will need the atmosphere to be thickened substantially - even if it's only a carbon dioxide atmosphere. This is the important factor; not the creation of huge artificial magnetic fields.

[I just re-read this post and what an angry-sounding unpleasant rant it seems to be. :rant:
Sorry! Just venting a little frustration .. that's all. Nothing personal, Chat.]

chat · 2005-03-14 06:26:29

Shaun,

Don't worry i didn't take it personally.

Wish i could place a link about the effects of increased ionizing radiation on life, but alas no good link exists.

I'm also all for teraforming mars, but like to look at the minor details before the big picture.

Since any form of a planetary magnetic field for mars is a long long way away (if even needed) then its probably a mute point anyway.

I'm 100% sure bacteria will survive on a teraformed mars, but will it be a high mutagenic form changing so often that it is unpredictable or unsalable.

Plants require a much longer propagation cycle than bacteria so any mutations on plants will be many times what happens to bacteria.

Engineered plants and bacteria for mars will probably work, but i doubt most untouched terrestrial forms placed on mars will happily grow.

Also since a teraformed mars will be mostly co2 atmosphere, wouldn't the rain and puddles be carbonated.

Carbonated water falling on a peroxide and rust surface should make for interesting surface chemistry, and even stranger puddles.

Those little details are sometimes the most interesting

Dook · 2005-03-14 07:21:10

Sometimes at New Mars I feel like we're going round in circles. It often seems that issues can arise, be discussed, have reasonable conclusions reached about them ... and then the same issues arise again as if the've never been discussed!

People are too stubborn! They hate to admit they are wrong and absolutely refuse to change their opinion.

I've been stubborn a few times here but I always change my opinion in the face of persuasive evidence.

Dook · 2005-03-14 07:32:17

No real problem with leaving a reactor in space that might plummet to the ground on mars.
When it impacts it will add to the radioactivity for a few 1000 years.
Even the shuttle going to space for a few weeks gets hit by micro meteorites.

Again, the reactor would be in a stationary orbit. How is it going to plummet? Is the martian gravity suddenly going to increase?

The shuttle is hit by man-made micrometeorites (paint chips) from the many previous rockets that have passed through. Meteor storms are predictable and they don't fly the shuttle in them. An actual impact with a meteorite would be devastating.

chat · 2005-03-14 14:15:35

Dook,

As a person is the study of plants for over 30 years i speak from some experience about how delicate life is, and how unadaptable it is to radiation.

One simple problem is that plants at 1/3 g will require 3x as much water to survive as they do on earth.
Very few plants can produce 3x the foliage water needed to sustain life on mars.

Since the atmosphere on mars will be less that 50% on earth that will also be a water drain to any plants that can be engineered.

Bacteria will also suffer the same sort of water loss.

You will also have to think of a climate that more like the far northern cool climate on earth with a minimum of 2x earth radiation, and many multiples more of charged particle radiation.
At the same time plants will only receive around 40% of earth sunlight.

The mutation rate for plants on the space shuttle over very short intervals proves that plants don't adapt well to increased radiation.

Human pilots also suffer a much greater risk of cancer only flying at altitude for less than 4% of a lifetime.

Living anywhere on a teraformed mars will be equivalent to flying at altitude 100% of the time.

I'm also only to happy to change my mind about adding earth life to a teraformed mars, but reality always gets in the way.

People just love to think of a lush green mars covered in trees, but the reality is that only the most highly engineered plants and bacteria will set up home on a teraformed mars, and the people just brief visitors to that world outdoors.

The reactor in space.....
Since all life on mars will need to be altered to mars conditions i doubt it will need one.
It would be a very expensive venture to place a reactor and in geo at mars anyway, and in 50 or so year life of such a thing a critical impact is almost certain.
Earth collides with around 100 tones of material from dust to baseball sized a day, so mars will be about the same sort of shooting gallery.

BobL · 2005-03-15 22:03:33

Everyone seems to agree that in order for terraformation to occur, there has to be some form of radiation shielding. Two different methods of radiation shielding brought up have been magnetic shielding and dome building. We know that magnetic shielding works and we know how it works, so what exactly would be needed in building a dome protect anything underneath it from radiation(dome thickness, etc)? What would be the desireability of an easy to construct dome with magnetic shielding than a hard to construct one with conventional radiation shileding(or would building a conventionally protected dome not be much harder?) ?
(By the way, please, Im not trying to argue about other requirements for terrafroming Mars, I just want to discuss Magnetic Fields and/or other alternatives for radiation dampening)

RobS · 2005-03-15 23:15:03

Chat, what do you mean that plants in 1/3 gravity need three times as much water? By that logic, plants in zero gravity would need an infinitely larger amount of water and could not grow at all!

As for sunlight, there are various ways to augment the sunlight Martian plants get. First, they won't be effected by clouds or experience the absorption the Earth's atmosphere produces. And if the dome is half as high as it is wide (as in a hemisphere) mirroring attached to the inside of the dome can bounce downward to the plants the sunlight that would have passed over them. Normally, a certain area of a sphere receives 1/pi as much sunlight as the same area pointed straight at the sun in space. But mirrored blankets on the inside of a dome, reflecting downward morning and afternoon light, will raise the total to about 1/2 the normal. The difference between 1/pi and 1/2 is substantial and will itself raise the total insolation that plants get from about 40% to closer to 65% of normal at the Earth's equator. That's about equal to the sunlight plants get in the US in March and September when the sun is not overhead. So crops could adapt to that light level.

As for space radiation effecting plant growth; have you actually seen a paper published on this? I've seen papers on effect of humidity and light levels, but not radiation. Plants can endure hundreds the radiation exposure of humans. I don't think radiation will be a problem for them on the Martian surface, or even in space for that matter, except during a solar storm (and only in orbit, not on the Martian surface).

Radiation will be a problem for mammals and birds. Keep your goats and chickens inside. But nowadays animal raising techniques keep them inside anyway (poor things).

I've also not seen anything about radiation effecting mutation rates of plants. Have you? I think I mentioned to everyone as a kid in elementary school buying radiation-exposed seeds (mine were morning glories) as an experiment. I suppose they were trying to help us not fear the bomb! My seeds were exposed to a lot of radiation (I don't remember how much) and I was disappointed that they all grew normally.

Regarding micrometeoroids hitting things in space, I don't think you understand how rare that really is. The shuttle's big danger is space debris orbited by people. As I think I mentioned on another posting, the seismometers on the moon detected one basketball-sized impact on a 2000 mile by 2000 mile object (the surface area of Africa) every five years or so.

-- RobS

chat · 2005-03-16 06:01:37

RobS,

At 0 g plants require about the same amounts of water as the do on earth, the capillarity action in 0 g and the transpiration levels are similar.
In fact at 0 g plants don't function well at all.

I will have to hunt out a link for you about plant water losses in micro gravity.
The general idea is that transportation rates of water for terrestrial plants is much higher in low gravity due to the size plants will grow at 1/3 g.

Plants grown at 2 g show that they use much less water and elements, so it seems pretty straight forward that lower gs will produce the higher numbers.

In a nitrogen and water restricted environment such as a terraformed mars, growing plants will be difficult since you will also need 3x nitrogen and 3x trace elements.
The vegetable garden should produce some gigantic things to eat though, offsetting the quantity you need to grow.

I also agree that in domes turning that 40% sunlight into 100% sunlight with mirrors is pretty easy.

No such luck for light enhancement outdoor though.

As you mentioned no animal life on the surface even on the teraformed mars, even if the radiation count is pretty good on a teraformed mars hunting for goats when a solar flare warning is happening sounds like no fun.

Living inside is a must for animal/human life on mars, but what about solar flares for any life on the surface that has no moving to shelter option?
Sure a thicker atmosphere will shield quite a bit from a solar flare, but unlike earth mars wont shield the radiation forms most dangerous to life anywhere near as well as earth does.

Ahh the old pea experiment.
Try that same experiment 6 or 7 generations along crossbreeding with radiated peas.
At about 5 generations you start to get some pretty strange results.

That same experiment in an Xray machine shows very different results.

Both experiments on living plants yields very different results to seed radiation.

Domes on mars also have a set of particular problems.
Internal external pressure differences will make for very robust structures.
A peroxide enriched surface on mars wont allow you to create the domes from materials such as rubber or plastics.
And pretty thick glass will be needed to fend off the last of the harmful radiation from the dome.

The reactor in space at mars.
The big baseball impactors for a reactor at mars are rare, but pea size gravel isn't so rare.
Would you stand outside a reactor on earth with a gun equipped with armour piercing bullets and a blindfold.
Each day you shoot just 1 bullet in a random direction.

How long before you have an unlucky day?
And even if it does last 50 years, when the reactor has used up its useful life what do you do with it?

BobL,

IMHO

If you build the entire dome underground you wont need any extra radiation protection or massive dome structure.

Light can be supplied either as all manmade or reflected light that in radiation free.

chat · 2005-03-16 20:07:26

Rob,

Still trying to find the original paper on low g plant growth.

Wish i had a darn bookmark for it as research is far and few between for + - g study on plants.

But this link goes a little into the problems with water transpiration at lower than earth pressures.

http://www.asgsb.org/programs/2002/122. … 2/122.html

RobS · 2005-03-16 21:30:11

I've seen the publications about increased water transpiration at lower atmospheric pressure. I don't see that as a problem. Greenhouses will recycle water anyway. If plants transpire twice as much, that means there will be twice as much condensation, either on the greenhouse sides or in its dehumidifers. Greenhouses will have surplus water anyway and Mars has plenty (drill down 100 meters almost anywhere and you'll hit regolith with ice in it, I'm pretty sure).

Where gravity is concerned, what you seem to be saying is that plants will grow larger in lower g and therefore need more water and nutrients because of improved capillary action. I have seen reference to capillary action working better in low gravity; that sequoia trees could grow maybe three times taller on Mars. But that doesn't mean that a corn plant will grow three times as high. Capillary action may improve a lot more in a 100 meter tree on Mars than in a 1 meter corn plant! Plant growth is controlled by a lot of things other than capillary action. Genes have a lot to do with how big plants will grow. Sunlight will modulate growth as well; vegetables grow very large in southern Alaska because of the near-perpetual sunlight.

Regarding animals on a terraformed Mars, if Mars has an atmosphere thick enough for wild animals to breathe, it will also protect them from solar and cosmic radiation. The magnetic field of the Earth does relatively little to protect us, especially against cosmic radiation. The thickness of the atmosphere protects us.

My reference to animals being inside was not for a terraformed Mars, but for animals inside domes in a small settlement. I tend to assume that terraforming will never occur, or not for at least several centuries.

As for peroxide effecting plastic domes. . . first, we are not absolutely positive there is peroxide (though it is likely); second, microscopic dust particles with peroxide on they may not effect plastic unless wetted; third, if peroxide is a problem, a coating may be able to protect the plastic, or a plastic dome could have a replacable plastic covering over it. Ultraviolet light is a similar concern and can be handled with coatings.

Regarding micrometeoroids in space; even bullet-sized particles are rarer than a collision per fifty years. But I don't know where to find the statistics. I will look.

-- RobS

chat · 2005-03-17 05:55:47

RobS,

I agree 100% that inside the dome most of the problems disappear or at least become manageable.

On a non teraformed mars its probably better not to even waste time building on the surface at all, maybe even a teraformed mars makes more sense not to build on the surface.

All structures underground with manmade illumination.
Going underground saves on heating, radiation shielding, structure robustness and indoor outdoor pressure differentials.

I'm in the same boat about teraforming mars.
Would love to see a teraformed mars but i also believe its 100s of years away if ever.
The cost and trouble to teraform outweighs the benefit.

If we are adventurous and do teraform mars to say 50% earth atmosphere, its the host of small problems that haunts us outdoors to try and make it earthlike.
1. increased cosmic radiation.
2. increased solar flare radiation.
3. increased background radiation.
4. different climate cycles.
5. different hydro cycles.
6. 1/3 g plant growth problems.
7. 1/2 atmospheric pressure plant transpiration problems.
8. increased nitrogen needs for plants from 6 and 7.
9. h2o rain that includes amounts of peroxide and dissolved co2.(guess on this).
Ponds almost guaranteed to be water, co2, peroxide and dissolved iron.
10. earth polar light condition on equator.

When you add up all the small problems it becomes a giant problem for life on the surface.
submerged aquatic plants might be the only plants that grow well on mars.

...
That reactor in space..

I wonder exactly how often sand sized things destroy geo satellites in earth orbit.?
Will be interesting to see the data.

I would hate to try and service the reactor after 10 or so years of service when it wears out a part.

Even if it does do a full 50 years service do you just leave it in geo when done?
Wait for the inevitable day when it arrives back to mars.
If its big enough to make a planetary magnetic field it is also big enough to hold an awful lot of spent reactor fuel.

If i lived on mars and someone came up with the idea i would stop paying taxes *lol*

RobS · 2005-03-17 12:35:40

As far as I know, no satellites in Earth orbit have ever been damaged by micrometeoroids, though orbital debris has done damage. I'll look for the stats; I've seen them somewhere.

I don't think it is necessary or desirable to grow plants underground. To feed a person requires about 100 square meters of advanced hydroponic or greenhouse-type agriculture, which requires 50-100 constant kilowatts to make the light (at 100% conversion of electricity to light!). That's a lot of power. I don't see why domes can't be made on the surface. They will not need heating because they will trap so much solar heat; a recent calculation at MIT suggested that cooling the domes would be a problem instead. The Martian atmosphere is so thin, it will not remove much heat through conduction, and it is easy to make domes that are nearly impervious to infra-red radiation. I think the domes will need to have a series of infrared-reflecting layers that can be added of removed depending on the energy coming in and the interior temperature. Domes will also need heat storage, perhaps in the form of fish ponds or water tanks.

As for cosmic and solar radiation, I don't think it will kill farm plants or even make them ill, even during solar storms. Maybe new seeds would have to be shipped from earth every few years to preserve the viability of the crops; or maybe seed crops could be grown underground. So I see no reason not to build greenhouses on the surface.

Furthermore, people need to be able to walk in greenery and in the "open air." Transparent greenhouses on the surface will provide both.

Longer term, I'd construct large (50-150 meters or larger) domes, put several stories of housing in them, and put agriculture on their roofs. The plants and wet soil would provide radiation protection for the housing and work spaces below. The courtyards between the buildings would have a park like design with grass, flowers, decorative food crops, and fruit trees (plus a few basketball courts, kids' playgrounds, and such). All buildings would possess very wide (1.5-2 meter) overhangs, so people could sit, walk, or stand and talk outside, enjoying the vegetation of the courtyards, while also having significant radiation protection overhead. Rooms would have windows facing the courtyards, but beds, desks, tables and other places where people spend a lot of time would be against interior walls, where there is more radiation protection. The windows would not open and would be airtight, so if the dome lost pressure the building would still be usable or at least would provide a temporary refuge for people fleeing the courtyards.

-- RobS

chat · 2005-03-17 16:49:21

Rob,

Maybe a combination of dome covered in soil with windows on the side, mirrors bouncing in the radiation free light.

That solution gives the best of all, natural light, radiation protection, less robust structures and easily expandable domes.

Good ideas for the housing in the dome as no space will be allowed to be wasted, safety will be a must for a dome disaster so the home shelter idea is a good one.
The plants on the roof is also a great idea. i think everywhere plants can be they should.

Water plants with fish, crayfish, freshwater clams etc grown in big tanks will go a long way to keeping the temperature even day and night.
Also quite a bit of food and o2 will be produced from them, the plants and animals in an aquatic environment will be much better adapted to any low g plant effects and transpiration for aquatic plants is a mute point.

Another benefit from the aquatic tanks is that waste from a dome might be fully recycled this way.

I also agree that living in a cave on a mars colony would be a very dull existence.
Green spaces are a must for people to live on mars and not just exist.
Grow just the mushroom crops in the caves, they care little about the light.

I forsee a west Edmonton mall sort of place where you can do pretty much everything from work to live to vacation all in one giant city like building.

srmeaney · 2005-03-19 10:07:04

It may not be possible to activate the martian magnetosphere. Terraformers may have to settle for a 'Plants only' ecosystem with an atmosphere of heavy gasses and Carbon Dioxide and Nitrogen.

Shaun Barrett · 2005-03-19 20:52:35

A little over 2 years ago, a few of us were discussing domes on Mars. This led me to look at Dr. Zubrin's ideas for domes and to suggest a minor modification which allowed for multiple floors of radiation-shielded well-illuminated living space. I think the design answers many of the requirements RobS quite rightly specifies for psychological well-being, too. (But it does call for significant earth-moving capability.)

Posted: Nov. 25 2002, 01:25
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Hi again, Josh!
I was just re-reading Dr. Zubrin's "At Home in a Dome" section in his book, The Case For Mars. (It starts on page 177.)
He describes a few different ways of tackling dome construction on Mars - and all but one involve the use of closed 'bubbles' of plastic. The odd one out is essentially a hemisphere of clear plastic with a skirt which is buried in the regolith, and possibly 'pegged' as well. This latter type is still presumed to be airtight, even though there is no floor in it except undisturbed Martian dirt! The trick is simply to hold the damned thing down by either burying the skirt and pegging (as Bob Zubrin suggests) or maybe by creating massive reinforced concrete footings, as we have discussed in other threads here over the past year.
One of Bob's ideas is to dig a hemispherical hole, say, 50 metres across (25 metres deep), place a spherical 'balloon' of reinforced clear plastic in the hole, and then bring all the tailings in through the airlock and fill the sphere up to ground level again! The trouble with this idea is the enormous amount of material you have to dig out and push back in.
A modification of this concept involves a hemisphere of clear plastic, again with a radius of curvature of 25 metres, attached to a section of a sphere with a radius twice as great. The section with twice the radius of curvature forms the bottom of the 'bubble' and is much shallower, requiring a correspondingly shallow excavation with a central depth of only 3.35 metres (instead of 25 metres). This way, the amount of soil moved is reduced from 260,000 tonnes to just 6,500 tonnes ... a hugely more manageable task!!
If you could find an obliging crater of shallow depth and about the right diameter, you could perhaps save yourself some of the excavation work, and maybe use the crater walls as 'backfill' inside the dome. I think this is the kind of thing Byron is suggesting (? ) and it seems like a good idea.
I was wondering about that first type of dome, though - the one which is simply a half buried sphere. I know there's a lot of soil to dig out (a hemispherical hole 25 metres deep), but what if you didn't put all that soil back inside at all? What if you made 6 or 7 floors of living area with a 10-metre-diameter central vertical shaft for elevators and for natural light. The roof of the topmost floor could be made level with the ground outside the dome, by covering it with a metre or two of soil for agriculture and radiation protection.
This would make maximum use of the volume of the sphere for radiation-free living space, while also maximising the free and open space in the top half of the dome for farming and leisure purposes.
I just haven't figured out what to do with the 260,000 tonnes of dirt outside the dome yet!!

It occurred to me later that a large transparent water storage container could be suspended over the central vertical shaft, allowing light to enter unhindered but also utilizing water's recognized radiation-shielding properties at the same time.

By the way, I still think Chat is being way too pessimistic overall about this radiation problem.

chat · 2005-03-20 04:20:13

Shaun,

Another solution to all that dirt moving is to create a structure with dust catching abilities and wait for one or two of the wild dust storms on mars.

I remember reading a paper about that a few years ago and it seems a great way not to have to move dirt with brute force.

I'm not trying to be to pessimistic about the plant troubles on mars, radiation is just one issue to deal with in the list of problems.

Not much point thinking about teraforming if the small things are giant headaches.
Plants are a lot more fragile than we would like to believe.
Until a few generations of plants are grown at 1/3 g and 1/2 atmosphere with additional radiation and 1/2 light I'm in the maybe to doubtful camp.

I'm sure all the problems can be solved at mars under controlled conditions, but i question if plants will ever survive unaided on a Martian surface with 1/2 earth atmosphere.

Shaun Barrett · 2005-03-20 18:46:40

Hmmm. ???
I think I've just noticed an error in Dr. Zubrin's assessment of how much regolith would have to be moved in digging out a hemisphere of 25 metres radius.
A hemisphere of that size has a volume of about 32,700 cu.m. In order to reach a mass of 260,000 tonnes, the figure in "The Case for Mars", the regolith contained in that volume would need a density of 7.94 tonnes/cu.m.
Even pure iron has a density slightly less than that, at 7.87 tonnes/cu.m!!
And so, on Earth, a cubic metre of iron would weigh 7.87 tonnes. On Mars, a cubic metre of iron would weigh 'only' 3 tonnes.

Mars' overall average density, including its iron core, is about 3.95 tonnes/cu.m. From this, it seems reasonable to assume that rocky regolith material might mass no more than about 3 tonnes/cu.m., which would weigh about 1 tonne/cu.m under Martian gravitational acceleration.

Therefore, digging a hemispherical hole of radius 25 metres, on Mars, requires the shifting of about 32,700 tonnes (weight) of regolith - not 260,000 tonnes.

I never noticed that error until now. ???

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