Mars Magnetic Fields Problem

The Bear · 2003-07-25 22:35:52

Does Mars' lack of magnetic fields place an insurmountable obstacle in the way of terraforming the planet? Would the production of a breathable atmosphere be defeated by the leakage of any artificial atmosphere into space?

space_psibrain · 2003-07-26 00:41:04

The obstacle is not insurmountable, but it means that compasses and traditional forms of navigation will not work. In their stead, i suggest a constellation of satellites to act as an Areo-Positioning System (Areo instead of Geo, Mars instead of Earth).

And yes, there will be leakage of the atmosphere into space. One of my colleagues calculated a decay rate of approx 90 years...so the struggle to terraform must be a dynamic one, in constant motion. Simply establishing a terraformed world is not enough...we must maintain the world.

Shaun Barrett · 2003-09-11 07:01:20

The question of how long a dense atmosphere would last on a terraformed Mars has been raised before.
When I saw Space_psibrain's answer of 90 years, I was taken aback! My recollection was a figure at least in the hundreds of thousands of years, probably millions.

I found this site where an estimate is given for a dense carbon dioxide atmosphere. (Scroll down about 60% of the way to the section headed 'Timescale'.)
The relevant sentence is:-

Pollack et al. have estimated that the lifetime of a thick CO2 atmosphere in Mars is on the order of 10^7 years [i.e. 10 million years] without any recycling.

Since the human race is very much younger than 10 million years old, and unlikely to survive in its present form for more than a few million years more at best, I don't think the decay of a new man-made Martian atmosphere is going to be a significant problem.

As I've said elsewhere, let's just concentrate on creating the atmosphere first. We've plenty of time to worry about losing it later!

alokmohan · 2003-09-19 05:40:16

atmosphere is quite stable I UNDERSTAND PROVIDED WE CREATE ONE. But there should be elaborate discussion on magnetic field.

RobertDyck · 2003-09-19 07:18:09

The dominant loss mechanism of CO2 will most likely be the formation of carbonate rocks. Pollack et al. have estimated that the lifetime of a thick CO2 atmosphere in mars is on the order of 10^7 years without any recycling.

That may be true for CO2; however Venus has the problem that its lack of a magnetic field lets solar wind impact the upper atmosphere directly. That dissociates water into hydrogen and hydroxyl (OH-) ions. The monoatomic hydrogen is whacked so hard it achieves escape velocity. Pioneer Venus found that hydrogen is blowing off the back of Venus still today. That is loss of water. If we create a humid atmosphere on Mars with no magnetic field, we will create the same problem that Venus has. How long before we loose all of Mars' water?

Shaun Barrett · 2003-09-19 19:33:52

Robert:-

How long before we lose all of Mars' water?

This may be an impossible question to answer at the moment, Robert. Your point is certainly a very valid one but there are extenuating circumstances at Mars, compared to Venus, including the fact that sputtering by the solar wind must be roughly only a quarter as intense at Mars' distance from the Sun. In addition, Mars does actually have some degree of protection as a result of its remnant crustal magnetic fields, some of which are remarkably strong and reach hundreds of kilometres above the surface.
Neither of these factors is going to completely eliminate the water loss problem, I admit that, but it all helps. And I do appreciate that what we gain in terms of magnetic field remnants and distance from the Sun, we tend to lose in terms of Mars' weaker gravitational hold on its volatiles. But I think we probably won't know for sure what the actual rate of water loss is going to be until we set up the 'experiment' for real!
We don't yet know, for instance, just how much water we'll have to play with. We don't yet know how warm, and hence how humid, we can make the Atmosphere; it may be more difficult than we think to maintain significantly higher global temperatures.
One more wild card is the so-called 'snowball comet theory', which you've probably heard of. The point of the theory is that the inner planets are still being peppered constantly with watery snowballs some metres across, which keep adding to the volatile inventory. If this turns out to be true, and it is only a fringe theory right now, then not only does Mars probably have more water than we think but its net rate of water loss, even with a denser and more humid atmosphere, may be quite low.
In any event, I think we are talking about a rate of water loss which, at least on the human time scale, is likely to be virtually negligible ... I hope!!

[Even if the rate of water loss is vastly greater than I have suggested, say a half-life of 10 or 20 thousand years, I am confident that our continually improving technological prowess will, by that time, allow us to recoup the losses in some way. In other words, we have plenty of time to worry about it later.]

Palomar · 2003-09-20 13:27:05

Pioneer Venus found that hydrogen is blowing off the back of Venus still today. That is loss of water. If we create a humid atmosphere on Mars with no magnetic field, we will create the same problem that Venus has. How long before we loose all of Mars' water?

*Oh terrific. Is there any way to manipulate what little magnetic field is already there (someone, a long time ago and in a thread I can't possibly recall the name of, mentioned that what magnetic field Mars does have is "patchy") into a larger, more global magnetic field?

Maybe the Reds will "win" by default.

--Cindy

Spider-Man · 2003-09-20 13:57:24

Yes, Mars's molten interior isn't nearly as massive or swirled into a single core, as Earth's is (this churning molten iron therefore stirring up the massive magnetic field we have). It's believed the primary maelstrom cycles inside Mars have broken up over time into smaller eddies, creating miniature versions of the greater magnetic field that likely was once dominant from within the Red Planet. These are sort of like minimagnets, giving Mars multiple and irregular poles across its surface, changing position and intensity most erratically, from what I understand.
This means that Mars doesn't have one big, protective field ensphering it, which would be ideal.

As for fixing a problem like that, heh... habe bona fortuna.

Shaun Barrett · 2003-09-21 07:30:11

Thi is the first time I've heard that Mars' magnetic fields are "changing position and intensity most erratically".
My impression was that the fields are 'fossilised', remnant, crustal fields, 'frozen' in place since the last time each particular region of the crust was last in a molten state.

This "smaller eddies" idea is very interesting, since it would help to explain the more recent volcanism on Mars.
I would be grateful for a link, SpiderMan, if you have the time.

Spider-Man · 2003-09-21 13:14:26

*Shrugs.* I learned that from a TV show, years ago on the Discovery Channel, before the mass cooking series took over, and they haven't produced a decent show since Discovery News went off the air. Try google.

alokmohan · 2003-10-10 05:24:31

A litle magnetism does not affect us much.Can you confirm or deny?

Shaun Barrett · 2005-05-12 06:43:56

Our ideas about when Mars' global magnetic field shut down may be wrong!
Check out http://www.space.com/scienceastronomy/0 … .html]THIS SITE.

Apparently, measuring a planet's crustal magnetism from Orbit isn't as accurate as we thought it was. I've lifted a couple of quotes from the article:-

Surveys in the 1990s of magnetic fields on Mars, by the orbiting Mars Global Surveyor, detected the signatures of relatively intense magnetism in some of the planet's more modern surfaces. But the fields were found to be very weak in two large and old impact basis, called Hellas and Argyre. Each basin, carved out by a colossal space rock, is more than 3 billion years old. The data implied that Mars had a weak magnetic field back then.

And:-

"Meteorite craters can then seem to be magnetic or non-magnetic, depending on how close the magnetometer is to the source," writes David Dunlop, a University of Toronto researcher, in an accompanying analysis. "Viewed from satellite altitudes of 100–400 kilometers [60-250 miles], martian impact basins would appear magnetically featureless if the magnetic vectors of their source rocks vary in direction over distances of a few kilometers or less."

We believe we know that Hellas Basin is 3 or 4 billion years old and our orbital measurements have found no significant magnetism in the rocks there. This seems to indicate that when the crust melted due to the impact energy, there was no global magnetic field to leave its imprint in the gradually solidifying lava. Logically, this pointed to a shut-down of the global field before the Hellas event.

Now that this new information is to hand, it's quite possible that Hellas, and Argyre too, actually do have crustal magnetism that isn't registering with our orbital instruments. This in turn means that the constraints on how long the Martian global magnetic field lasted may be too stringent - the field may well have persisted into the last 3 billion years before petering out. In fact, for all we know, our current maps of the crustal magnetism on Mars may be completely unreliable and Mars may have retained a planetwide magnetic field for very much longer than we think.

For what it's worth, I still wonder about Dr. J. Marvin Herndon's hypothesis about planetary cores consisting of enormous natural fission reactors. This doubt being cast on our whole understanding of Mars' magnetic history leaves open the possibility that Mars could still generate a global magnetic field, at least sporadically.
Maybe we just happen to have arrived at a time when it isn't functioning (?). [Just a little more speculation.]

Palomar · 2005-05-12 07:27:38

Our ideas about when Mars' global magnetic field shut down may be wrong!...snip...

Now that this new information is to hand, it's quite possible that Hellas, and Argyre too, actually do have crustal magnetism that isn't registering with our orbital instruments. This in turn means that the constraints on how long the Martian global magnetic field lasted may be too stringent - the field may well have persisted into the last 3 billion years before petering out. In fact, for all we know, our current maps of the crustal magnetism on Mars may be completely unreliable and Mars may have retained a planetwide magnetic field for very much longer than we think.
For what it's worth, I still wonder about Dr. J. Marvin Herndon's hypothesis about planetary cores consisting of enormous natural fission reactors. This doubt being cast on our whole understanding of Mars' magnetic history leaves open the possibility that Mars could still generate a global magnetic field, at least sporadically.
Maybe we just happen to have arrived at a time when it isn't functioning (?). [Just a little more speculation.]

*Hi Shaun: I saw that article yesterday but didn't have time to read it extensively, much less post and comment. Fascinating to consider -- all of it.

Your last question is especially intriguing. It's a good mystery, huh? Another item of interest to keep tabs on. Have long been curious about Mars' magnetic field; will be great seeing further info/speculation roll in.

--Cindy

Commodore · 2005-05-12 17:40:23

The radiation issue will sooner be solved medically than geologically.

Although I wonder if creating a thicker atmosphere will slow down or stop any bleeding of thermal energy rising off the core, heat that could build up, and perhapes spin things up a bit.

karov · 2005-05-13 03:05:48

The thickened and humid earthlike terraformed mars atmosphere retention should be approached from two sides, which I think are completely surmountable obstacles taking in mind the modern mass market technologies.

1. First we should prevent the atmosphere from dissipating in space due to the action oif the solar radiation: This could be done by intensifying the planetary mag field: Encircling the martian globe accross the equator on the surface with 21 000 km long cable is a task which we here on Earth on regular basis fulfilled in thousands of times greater dimensions - highway, railway and powersupply lines` networks. This cable or coil of cables even shouldn`t be superconductive, just the electriic flux along it should be with certain intensity. Superconductive cable is better cause the introduced el.currant will flow "forever" and this equatorial coil would serve also as power reserve for the martian economy. The other opportunity is the coil to consist of nano-tubes, along which the electrons to be flied balistically -- this also reflects the definition for electric currant.

2. The other issue is the carbon sedimentation. As the uoted sources point out the humid atmosphere and the presence of liquid water will cause the vital CO2 to be captured in sediment rocks in just 10 Myr. On earth the sedimented CO2 is continuously released via the crustal plates subduction and pyrolysed by the interior heat. This is the planetary thermostat in action.
On Mars or other smaller bodies we should establish mechanism to keep the necessary level of CO2 in gasseous state in the atmosphere: Solutions:
- create artificial volcanoes via introducing artificial "hot spots" in the upper mantle with liquid magma. The volcanoes will spit lava which wight will pull down the lava poured over sedimnts into the liquid zone whee the sedimentys will be pyrolyzed and CO2 released.
- use some artficial biogenic method - some kind of sedimnt eating bacteria
- Just use brute force industrial methods of "burning" the carbonated rocks. We now do it on Earth for various purposes - just increase the scale...

The equatorial coil for intense global mag-field and the carbonated rocks burning is so simple, that we even could calculate the price for maintenance on annual basis.

Note, that every planet should be maintaned for human livability. We have the thermostat and the magfield for granted here on Earth, but the tectonics every year causes damages for hundreds of billions of dollars via volcanic eruptions, earthquakes, etc. In other words each of us pay at least , say 10-20% of his/her income as kinda rent or tax to the planet in order to live on it. The Terraformed Mars with artificial magfieeld and CO2 thermostat, + artificial cycle of the other important planetary chemicals ( oxigen, water, nitrogen, etc.) dffinitelly would be much more cheaper for living per one human life per year than the fat old mother Earth.

Shaun Barrett · 2005-05-13 03:57:39

Hi Karov!
I don't know if your cable around Mars will work to create a planetwide magnetic field or not. Perhaps it will and I hope it does some day.

As for the CO2 turning into sedimentary rock, all we have to do is ensure that the pH of the Northern Ocean and various seas is kept sufficiently acidic. Not acidic in the sense that it would be dangerously corrosive to humans enjoying a day at the beach, but just acidic enough to preclude the formation of carbonate rock.

Apparently, this can be achieved as long as the pH is kept less than 6.2, as described in this Abstract of a paper called "Inhibition of carbonate synthesis in acidic oceans on early Mars", by Fairen AG, Fernandez-Remolar D, Dohm JM, Baker VR, Amils R. :-

Several lines of evidence have recently reinforced the hypothesis that an ocean existed on early Mars. Carbonates are accordingly expected to have formed from oceanic sedimentation of carbon dioxide from the ancient martian atmosphere. But spectral imaging of the martian surface has revealed the presence of only a small amount of carbonate, widely distributed in the martian dust. Here we examine the feasibility of carbonate synthesis in ancient martian oceans using aqueous equilibrium calculations. We show that partial pressures of atmospheric carbon dioxide in the range 0.8-4 bar, in the presence of up to 13.5 mM sulphate and 0.8 mM iron in sea water, result in an acidic oceanic environment with a pH of less than 6.2. This precludes the formation of siderite, usually expected to be the first major carbonate mineral to precipitate. We conclude that extensive interaction between an atmosphere dominated by carbon dioxide and a lasting sulphate- and iron-enriched acidic ocean on early Mars is a plausible explanation for the observed absence of carbonates.

The absence of significant carbonate deposits on Mars is very encouraging to us serious terraformers as it tends to remove the concern that any early Martian CO2 atmosphere has been lost irrevocably to dissolution and sedimentation as carbonate rock.
This would seem to indicate that the remnant atmosphere, which escaped blasting into space by meteoritic bombardment in the earliest epochs, has probably been adsorbed onto the regolith, as suggested by many authorities including Dr. Zubrin. This adds credence to the notion that warming the Martian surface could indeed release maybe 800 millibars of CO2 and maintain an efficient greenhouse effect.
:up:

karov · 2005-05-13 12:06:42

Hi Shaun,

1. The artificial magnetosphere - it will work deffinitely using this:
http://en.wikipedia.org/wiki/Magnetic_s … netic_sail
but put on surface, encircling the planet around the equator, other circumference path or by making entire mag-cage criscrossing over the face of the planet, or better:
one of these:
"blowing an arc" around the entire terraformed body, or combination of these two. All such systems are power dependent, but on Earth keeping the enormous disequilibrium between the "fuel" ( Giga and giga-tones of biomass per annum) and the free O2 also consumes enormous constant energy influx.
On Mars, Moon, every small body with unsufficient gravity to bond free fluids -- artificial magnetospheres with much more teslas than earth`s where necessary will be deployed and permanently solar powered.

2. Yes, the acidity of the water bodies -- thank you for the reminder. Of course it is simpler to "pepper" the terraformed Martian oceans with iron.

To terraform in the strict classical sence of open air ANY world ( I mean any selfrounded via selfgravity celestial body), we need ONLY the money and the will to do so.

Shaun Barrett · 2005-05-13 18:54:23

Yes, Karov.
I do understand the basic principle of using a vast loop of current to create a planetary magnetic field. In fact, if I remember my physics correctly, the existence of an iron core inside a planet would serve to enhance the efficiency of such a field(?).
And I do realize that, given sufficient energy, engineering prowess, and human willpower, there's no fundamental reason we cannot undertake such a task.
And, what's more, I do admire your vision when it comes to planetary-scale engineering and your obvious enthusiasm for such projects. I also look forward to the time when such amazing feats of technology will be achieved - and I admit they may be closer than I imagine. Perhaps I'm too timid. Perhaps I'm forgetting what Sir Arthur C. Clarke has taught us, that most failures of prediction stem from a failure of nerve - technology almost always advances farther and faster than most of us foresee. So you may well be right to pursue this line of reasoning so vigorously.

One or two particular thoughts I'd like to air, by the way, while I'm on the subject .. I always imagine that any loop of superconducting material around Mars' equator will need to be able to carry such an enormous density of current that it's construction will be untenable for a long time. Also, I wonder whether the localized fields generated by the massive current will have detrimental effects on the environment in the immediate vicinity of the equator.
There are questions being asked here on Earth about the potential (pun unintentional .. sorry! ) for power lines near residential communities to cause cancer - and the electric current in these cases is negligible compared to the current we'll need for our Martian project. If so, will it be necessary to fence off large swathes of equatorial real estate to establish a safety buffer zone either side of the cable? ???
Admittedly, even if such a buffer zone were necessary, we may decide that it's a fair exchange - to lose so many millions of hectares of habitable area at the equator in order to allow unfettered colonization of immense areas of radiation-shielded land to the north and south. Who knows?

Personally, my hope would be to create an atmosphere dense enough to shield the surface from harmful radiation, even in the absence of a global magnetic field. I feel that this is probably a more attainable goal in the short term. Such an atmosphere, it's been established, will last for millions of years, despite the ravages of constant 'sputtering' by the solar wind and the blasts of Coronal Mass Ejections (thank you Cindy for alerting me, and perhaps others here, to the surprising power and frequency of such events. :up: )

Just touching on a 'pet theory' dear to my heart. I still have hopes that Mars is much more volcanically alive than it's been given credit for and that it may still generate a substantial global magnetic field at intervals. This pet theory, as I've often mentioned, depends to a large extent on the as yet unconfirmed ideas of Dr. J. Marvin Herndon about natural fission reactors in planetary cores.
Earth's magnetic poles reverse every so often, with the North Pole taking up residence in Antarctica and the South Pole moving to the Arctic Ocean. Have a look at http://www.gi.alaska.edu/ScienceForum/A … .html]THIS ARTICLE, called "When The Poles Flip" by Larry Gedney. :-

More than 20 years ago, the first conclusive evidence was found on the sea floors that the earth's north and south poles have switched places repeatedly over the course of geologic time. The last reversal occurred some 710,000 years ago. For most of a million years before that, the north pole was the south pole and vice versa. Epochs of shorter duration on the order of 50,000 years can be found in the geologic record, but for the most part, each seems to last between 200,000 and 1,000,000 years.
No one knows how long it takes to make the transition. It may take a few years or it may take a few thousand (a few thousand years is about the shortest time interval that can be reliably measured from sediments and lava flows on the ocean floor). What is known from measurements of remnant magnetism in ancient pottery shards is that the earth's magnetic field has weakened by more than 50 percent in the past 4,000 years. In other words, we may be headed into another reversal.

If Mars is still geologically active, it seems reasonable to assume that its poles reverse periodically too - perhaps more sluggishly than Earth's since its smaller volume means it's probably losing energy to space faster.
It follows that it must also have intervals during which there is no global field, just as Earth does. In the case of Earth, these intervals may be years long or thousands of years long - no one knows for sure - and any such intervals on Mars may be correspondingly longer.
My view is we could conceivably have arrived at Mars, just by chance, during one of these pole reversals. We could be pleasantly surprised, in the millenia to come, to find our Martian colonies protected by a brand new natural magnetic field, without having to create it ourselves using mega-engineering.

On that 'Pollyanna-style' note of fairy tale optimism, I'll sign off. :laugh:
(Thanks for your patience. :;): )

karov · 2005-05-14 03:01:52

Excuse me Shaun,

in my post I forgot to put the link for M2P2:

http://en.wikipedia.org/wiki/Mini-magne … propulsion

as an alternative or aditional support for equatorial groung cable loop. The concept could be expanded to global planetary scale, such way the ionised trying to escape gases will be made to turn into the very hardware of the atmosphere retention machine. In M2P2 scenario the artificial magnetosphere provides the "bottle" for the plasma, which on its turn is the source of the mag-field. Two statites in polar halo "orbits" could provide all the energy necessary to constantly push the escaping air down and for the ionizing arc`s action.

About the harmfull effects of the currant in the supeconductive line, I `ll check and respond. ( you make me to dig into calculations about currant intensity, etc.).

Indeed, do the superconducting loop pumped with "forever" circulating amount of electricity emits anything? That would mean the currant will decrease rapidly. I don`t know, reading about the SC loop mag-sails, I am left with the impression, that the craft loses negligible amounts of energy to keep the sail up...
Also, in blured format I remember that the SC actually confine the resulting electromagnetic field change...

Even if such irradiation inevitably occurs, it could be easily isolated in Faradey`s coffin or in system which recovers the energy leak in good degree. Such way could harmlessly work, say, non-SC version.

Please, share with us other means which you know for re-exciting natural mag-fields. If we are able to "recharge" the natural areomagnetism "batery", once a several millennia or Myr, it sounds perfect...

Shaun Barrett · 2005-05-14 06:51:56

Thanks Karov.
I haven't really considered the M2P2 in any great detail before and your link was very informative. It's quite a concept, when you think about it, sounding like the ultimate 'bootstrapping' technique - with the plasma conducting the current, which makes the magnetic field, which in turn constrains the plasma!
It really is a remarkably elegant idea, if it can be made to work in practice.

But I don't see how it could be used to shield a planet. The M2P2 thruster is actually enveloped by the plasma cloud it produces; i.e. the magnet/plasma generator sits in the centre of the cloud, except of course when the solar wind acts upon the cloud and causes it to 'billow out' to some extent, away from the Sun.
Ideally, I suppose, you'd position your planetary M2P2 thruster (or shield, in this case) at Mars' core, but this is impracticable. If you position it at some point in space, presumably sunward of Mars in the expectation the cloud will billow out toward and around the planet, how do you propose to prevent it shifting? Even if you place it at the Sun-Mars L1 point, won't its vast plasma cloud tend to move it away from the stable point? Perhaps you know of a modified L1 point where the gravitational fields of Mars and the Sun, and the lateral force of the solar wind on the plasma cloud, are all in equilibrium? And wouldn't the Martian ionosphere interfere with the inflation of the plasma cloud anyway, as it expanded to engulf the planet? ???
I just don't see how you plan to make it work.

As for the Mars-girdling superconducting cable, if its creating a magnetic field through and around the rotating planet, this will create eddy currents in the planet's interior, and thus secondary magnetic fields opposing the planet's rotation. Of course, these eddy currents and secondary magnetic fields will have a completely negligible effect on the planet's rotation rate because Mars is such a massive body, but they must necessarily cause energy loss to the system by creating heat which is ultimately dissipated through convection and radiation. (Please correct me if I'm wrong.)
Since there's no such thing as a free lunch, I think you'd have to pump energy into your cable to maintain the current, even if the cable is superconducting - which it would have to be in any case to maintain such a massive current over a distance of 21,000 kms. Any appreciable resistance would surely become problematic over distances far less than that.
And we're assuming we'll have materials which superconduct at average temperatures of maybe 290K on a terraformed Mars, of course. Presumably not a problem in the future we speak of.

Oh, and unfortunately I have no idea how to go about "re-exciting natural mag-fields". All I'm hoping is that Mars will automatically re-start its global field as and when the fission products 'poisoning' its nuclear reactor core float out of the core and allow the chain reaction to once again heat the interior of the planet and create the convection currents necessary for that field to exist.
But all this depends on the vindication of Dr. Herndon and his controversial hypothesis.

karov · 2005-05-15 03:43:51

1. The planet-wide M2P2:
From wiki a quote: "The basic mechanism looks like a coffee can with both ends open. Gas is emitted from a valve in the coffee can. The coffee can confines the gas long enough for some electronics to strike an arc through the gas. Then a low voltage (low electrical pressure) high-current (lots of electrons) electric current is pushed through the arc. The magnetic field from this current "traps" the plasma of the arc. The conductive plasma finds it hard to move in the magnetic field because whenever it cuts the magnetic field, eddy currents form opposing magnetic fields and stop the motion. The magnetic field naturally wants to expand. This causes the arc to grow, and confines the ionized gas in the arc. This process is called "blowing the arc."

- The coffee can will be the whole planet. Hovering over the poles we put two solar-sail statites, which provide the energy and/or accelerate electrons for forming he arc. It is not necessary the system to follow the closest path through the planet`s core, but indeed the field forming arc could curve around the planet or the currant to be mediated via on groung electric power line ( with say ionising the air laser connecting the poles` surface with the solar power statites). The rick is to close the currant/field lines. The Sun-Mars L1 point is perhaps also suitable. The halo orbit of the instalation there would be logically maintaned by sun power and constant maneuvres...

- The gass supply is provided by the constant rise of iones achieving close to escape velocity, bombarded by the solar photon and particle radiation.

- the plasma cloud and the martian ionosphere would be one and a same thing, the last tamed this way.

Providing M2P2 style artificial magnetosphere in principle makes possible to open-sky terraforming even of Vesta or Hygeia ( bodies with little radius and 2-3% gees suface gravity)... giving sufficient power supply and ignoring the fact that Vesta or Ceres with 0.2-1 bars surface air pressure would need perhaps Jupiter-size or bigger artificial iono-magnotisphere in order to counteract to the internal pressure.

Other very important option is that we actually could "program" these iono-magnetospheres not only to electrmagnetically to redirect back the trying to escape ions or just to steal their escape velocity, BUT also via utilizing Peltier and other kind of thermo-electromagnetic effects to cool down the plasma , providing multiple iono-pauses, which to serve as bariers counter gas escape. At terraformable moons of gas giants, the gas-retention artificial magnetosphere would be actually magnetotohr in shape.

2. About the grounded mag-sail version. Deffinitelly will be necessary power resupply. High temperature SC or cheap ways of refrigeration/insolation of the cable are feasible...

About the eddy currants - I think NO, the cable and core corotate.

3. Re-excitement of natural mag-dynamo? Nothing occurs to me.

I think the M2P2 way is the best.

Shaun Barrett · 2005-05-15 05:14:03

Karov:-

About the eddy currants - I think NO, the cable and core corotate.

Yes, I was thinking about this in bed last night, after I posted, and I realized I hadn't been specific enough. Of course, the planet's crust and the field co-rotate, so there would be no mechanism for energy loss there.
But it's known that Mars' interior is not solid all the way through - the core, at least, is molten. (See http://www.fourth-millennium.net/missio … .html]THIS SITE.) :-

The fact that the core is decoupled from the crust, and will inevitably experience convection currents influenced by Coriolis forces, means there will be different rates of rotation between crust and interior.
As long as there is electrically-conducting material moving independently of the crustal rotation, there will be eddy currents and secondary magnetic fields opposing this relative movement. These will each constitute a pathway for energy dissipation and therefore a drain on the energy of your equatorial cable.
[My apologies for the vagueness of my initial summary of the situation.]

Thank you for your more detailed description of a planet-girdling M2P2 magnetosphere. Perhaps it would work; I'm not sure.

karov · 2005-05-15 10:36:14

Thank you very much!

I wasn`t sure about the molten state of the martian core ( and honestly I was lasy to look about this).

Indeed the molten core saturated with electroconducting materials is an advantage , not obsticle infront the GroundMagSail version. Isn`t it the best way to excite the natural planetary magnet to as higher number of teslas as necessary? The currant in the equatorial SC cable will lose energy via the described by you effect, but this could be harnessed via proper energy management. Actually the "lost" electric energy will be invested as energy of the static magnertic field of the molten core. You point by the way the most logical waste energy sink in this system:

- the SC cable doesn`t loses energy via electromagnetic radiation.
- the iron core sucks in part of the energy via induction of curants in it.

In fact the whole system - SC cable with runing in it high intensity currant + the iron core which it surrounds will act as giant electromagnet, where the magnetic field is excited by the electric currant, the electricity bills will be payed only for repeatable "refill" , for re-magnetisation of the core.

Version 2 the M2P2 planetary-scale system is better, cause it is not dependent of whether the body has iron core, or other electroconductive materials in its interior ( like salty water) or not, hence is aplicable everywhere we decide to retain atmosphere ( even arround small icy bodies). Because the plasma itself acts as / replaces the iron core or underground salty water, the electroconducting material , for producing the mag field.

But off course it is much more practical to take the natural advantages provided en situ and in occasion.

Marses with SC cable, Lunas with M2P2...

Question 1: how intense magfields could be tolerated by the human organisms or other organisms part of our eco-life support system?

I ask this in connection with the notion that if M2P2 confines fluid/plasma without any gravity, than VERY small bodies could be atmosphere-retained ( apart from the question how much this is economical). If we decide to hold , say, half bar of O2/N2 atmosphere around, say, Ceres, how much intense should be the mag field of the M2P2 version system?

"Question" 2: There should be way the M2P2 design to be made to harness the necessary energy to push the atmosphere down from the central star directly, without solar power statites, etc? I mean self-containing self-powering plasma hardware.

Shaun Barrett · 2005-05-15 17:51:59

Hi again, Karov.
I think there are many more questions here than answers. To begin with, the way in which planets generate magnetic fields is still not fully understood - or at least agreed upon - by geophysical scientists.

I certainly don't claim to understand planetary magnetic field production, so you're probably talking to the wrong person. But it seems to me the energy loss from your equatorial cable on Mars is unlikely to " .. be invested as energy of the static magnertic field of the molten core", as you suggest. I see this energy being lost as just a little bit of extra heat in the planet's interior.
But, as I've said, I'm not an expert and I could easily be wrong.

If we assume an M2P2 magnetosphere can be established around a celestial body, the field will only act on charged particles. The bulk of a 500 millibar O2/N2 atmosphere around Ceres (assuming you could achieve such an atmosphere - and I have extremely grave doubts) will consist of atoms and molecules, not ions, and so will pass quickly, in bulk, through the magnetosphere and disperse in space.
I imagine you are visualizing a constrained ionosphere of such density that the atmospheric molecules will be unable to push through(?). I don't believe that's feasible.
Since Ceres' gravitational field is negligible in this scenario, you're asking your magnetosphere to resist gas pressure of some 5 tonnes per sq.m. This is reminiscent of the kind of force field we see in Star Trek .. and we don't know how that works either!

Sorry to be a party pooper but, on close analysis, I think your ideas tend to break down. No offence intended. ???

karov · 2005-05-16 04:42:45

Hi again, Karov.
I think there are many more questions here than answers. To begin with, the way in which planets generate magnetic fields is still not fully understood - or at least agreed upon - by geophysical scientists.

Hi Shaun!

1. About the planetary magnetism - of course my whims are just guesses ( not so wild), but provided with some grounds in what you also mentioned: We don`t yet fully understand the way round celstial bodies produce magnetic potential, but the logics point that , yes we observe natural mag-field everywhere we have electroconducting material in the body`s interior:
- Mars has molten core and some magnetism, mostly residual,
- Mercury has magnetosphere of about 100 times lower intensity than Earth`s - sign for molten interior, assuming its high density and strong for the size gravity.
- The Earth itself!!!
- The gas giants with their metalic hydrogen cores and non sinchronous rotation in terms of layers and latitudes...
- Some of the big gas giant moons with tidally warmed interiors, where we observe some magnetism, explained as consequsnce of presence of liquid water, satuarted with salts - i.e. elctrolite, solution providing currants.

This planetary magnetism also is connected with the rate of rotation of the body no mater axial or orbital, i.e. moving through mag-fields: Mecury is close to the Sun so it is immesed in its field with higher intensity, Venis - the opposite is further away and rotates slowly, Ganymede..., The Earth!experiences high tidal activity from the Moon which may be causes the magnetic force and the planetary bulk to non co-rotate so precisely and amplifies the magnetism, Jupiter with its high turbulence and non-sinchronous rotation.... The exact mechanism is not known, but we could using the method of the exclusion, to feature the coinciding items in each case and to build some sound hypothesys on this... In the case of the planetary magnetism mechanics - the obvious thing is that it is connected with presence of a conductive material part of the body, which possesses higer degree of freedom , than the generaly static whole.

In the upper sence we could either repeat/copy/mimic the process, or amplify it stressing on some part of the "equiation".

2. In Martian case - imagine that the semi-molten/semi-solid iron core ( as in the Earth`s model) is indeed already "tired" chunck of natural magnet. The Equatorial SC cablee or rather loop combined with this makes electromagnet. If you take normal piece of iron and use it as a core for electromagnet, runing electric currant around through a coil, the result is that the iron piece magnetizes, and stays with static magnetic properties for a comperativelly lond while after the electric supply is turned off. The "tired" magnets could be re-magnetised.
Such way of re-magneetisation agrees with the foremeentioned most simple model, supported by the most of the geophysisists - in this case the iron core stays, the currant moves...

3. In M2P2 scenario the plasma bulk is the magnet itself. Actually the M2P2 planetwide "coffee can" it is not necessary to run through the core at all. We could provide it at one of the poles only. The field would be assymetric , but the task is to make it enough wide to ncompass the whole planet. Yours notion about the L1 based "coffee can" might be better, cause always facing the sun, it could harbvest the solar wind from, say 1000 000 km wide area and to pass it through in MHD generator, which also to provide the necessary energy to run the system. In this case the northern magnetic pole will face the Sun, so we could deflect all the plasma to stay around not to be blown in tale in the solar wind shade, along the mag-lines tending to sweep the ions toward the planetary antipode ( where the south pole rotatees) and to follow paths leading them to lose escape kinethic energy via "aerobraking". The polar shines will then hover over the equator and ould appar at noon and midnight, accoeding to the axial rate of rotation.

Rotating magnet ( the tamed ionosphere turned into M2P2 planeta-wide bubble), suffices the requirement for differemce in the degrres of freedom of the solid planet and the magnetic force poviding material.

In your favourite theory about the core nuclear reactors
( perhaps absolutelly right, having in mind the chemical differenciation by mass, that undergoes in any even not so large body), the infra-planetary fusion, provides the energy which to power the differential movemnt/rotation/ of the whole planet and the conducting materials. This gives another approach possible - to reheat the Martian core in order to revive the stronger in past magnetism. For which we have in our theorethical arsenal number of means, no matter how economical or feasible in engineering sence... Every way to inject heat in is good, since the natural core reactors are just a heater amids various artificial possible too: light drilling, multiple explosions of hydrogen GIgaton bombs very deep in... or uge neutron bombs in order to enrich the depleted uranium/torium stopckpile...

3. About Ceres and other planetary dwarfs - the mentioned 5 t/m2 are just close to the surface, upper say 1000 km or 10 000 high the neutral gas rarifies enough in order to be passed entirelly through the very huge in this case M2P2 "coffee can" in order to be ionized completely. May be the tamed ionosphere= magnetosphere will be as big as the Jupiters , although thousands or millions of times weaker, but this way we could return all the neutral molecules back after manage to ionize them. Harnesing the solar wind for energy source for that machinery from these perhaps trillions of sq.km., on first glance appears enough for keeping the magnetic atmosphere shield in place and alive.

When I have time I`ll do more calculations and will report.

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