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#1 2007-04-11 00:47:51

RickSmith
Member
From: Vancouver B.C.
Registered: 2007-02-17
Posts: 244

Re: How Quickly Does Mars Lose Air?

Hi everyone,
  When I have time I have been working my way back thru the old posts.  I found an interesting thread.  Unfortunately, it is filled with a giant political debate (e.g. the economics of the USA debt, was the USA justified in invading Iraq, etc.) which buried the material on terraforming.  What I am doing is collecting the more interesting posts and hopefully restarting the thread with out the garbage.  We begin with EarthWolf's question:

Hello,

I remember seeing a documentary on the possibilities of terraforming Mars. The problem as the program stated was that Mars' gravity is too weak to retain any atmosphere that humans could engineer. That in a sense, Mars would be a leaky bag, seeping air and heat into space. Is that possible?

Cordially,
EarthWolf

I found this article here...

http://physicsweb.org/articles/news/8/9/14/1

They suggest that between 14 and 34 meters of water have been lost from Mars over its whole history by 'sputtering' from the solar wind.  If you blow up the graphic at the top of the article, it suggests that the solar wind is eroding (very approximately) 100 tonnes of gas per day.

Hmmm… I would expect that even earth leaks air. ...Moreover on earth if an escaping partial gets ionized before it is beyond earths magnetic field it would be recaptured. I would additionally expect that earth captures some of the solar wind which adds to the atmosphere. Micro comets also help to replenish the atmosphere. I wonder if earth’s atmosphere is in equilibrium, growing or decreasing.

On Mars what needs to be done is to lay a supper conducting loop around the equator. Or maybe the cable should be closer to the poles to keep the cable cool as the temperature of mars rises.

Hey John,
You are of course correct that the Earth leaks a bit of air but there is a major difference between Earth and Mars.  Earth has a "cold trap" in the troposphere where water can't rise into the stratosphere.  (It freezes to ice crystals before it gets that high.)  This means that the water always stays below the ozone layer and we do not lose much water to photo-disassociation.

This is why I want to beef up Mars' oxygen level as soon as possible even it we never get a human breathable atmosphere.  With an ozone layer we will slow water loss on Mars by creating its own cold trap.

As for your comments on a giant electo-magnet to give Mars its own magnetic field the job is far greater and more difficult than you may think.  This would probably be worth starting a whole thread for another time.  Anyway, you might find the following interesting:

// This link reports that someone has taken out a patent for a 150K
// superconductor. The old record was 138K and has lasted for years.

http://www.superconductors.org/150K_pat.htm


There was some debate about if it would be profitable to mine the asteroids.  If we have a Mars base with enough greenhouses to export food and air then it would get a lot cheaper. 

Karov was nice enough to share the link below that proports that using the technology the page author suggests, it is profitable now to mine the asteriods.  (I have not checked his figures but I have no reason to doubt it.)

http://www.neofuel.com/

The above is a bit off topic but such technologies could be used to drop comets or iceteroids on Mars and thicken up its atmosphere.


Anatoli Titarev gave an interesting post that talked about the interaction betwen the magnetosphere and the solar wind. I've abbreviated it a bit below...

...
With a strong artificial magnetic field the atmosphere retention would much better for Mars, the Moon and other bodies with a lower gravity. That would be the measure required. It would protect the bodies from the solar wind. Even Mercury can support a tenuous atmosphere thanks to the significant magnetic field it has (its power is only 1% of Earth).

Thanks to ERRORIST in his new thread (Earth's Magnetosphere)
Magnetosphere

I am impressed with the picture of Earth pushing away the solar wind with a shockwave of magnetosphere (5 times Earth's diameter) away from itself.

h_magnetosphere_diagram_02,1.gif

Karov also gave a link to a different article on this subject:

http://www.universetoday.com/am/publish … hield.html

Karov's post is too long to quote but this is the URL to it...

http://newmars.com/forums/viewtopic.php … c&start=60


Atomoid references the 2004 July / August issue of the Planetary Report which discusses how needed a magnetic field is to keep an atmosphere.  Some of the main points...

- For a 1 atm pressure atmosphere you need more gas (because the lower gravity does not compress it as much).  This thicker atm. actually gives more radiation protection with out a magnetic field than Earth does with it.

- The article says that 2 m of water was lost over 4 billion years.  (This is less than the 14 to 34 meters quoted above.)  A thicker atm. won't erode faster than the current one, so if we give Mars a new atm. it would last a very long time.  e.g. billions of years.

- The article suggests that the water has not been lost but is frozen under the surface.  It then talks about McKay / Zubrins terriforming idea.


MarsDog gave us this link on the history of the giant solar storms from 2003.

http://www.cnn.com/2004/TECH/space/07/0 … orm.proof/

Shaun Barrett pointed out that Mars may have had a magnetic field in its early history and the Sun may well have been less active back when it was only 70% as intense as it is now.  So the amount of water lost may be less than these estimates suggest.

SpaceNut posted the URL that I listed at the top of this post, that suggests the amount of water lost was greater (i.e. 14 to 34 meters globally).

A couple of short posts I give entire...

Even if Mars has lost a global equivalent depth of 34 metres of water over its history, it seems likely to me that enormous reservoirs of water still remain.
    Topographical evidence strongly suggests that Mars must have started with a global equivalent ocean of water some hundreds of metres deep. Unless we can show that that much water must have escaped, we can only assume most of it is still there.

If it all went under ground we need a volcano to spit it back out? There is no big moon we could easily add to mars to bend the crust and get the lava flowing again is there? Or maybe we could microwave mars. Well not exactly microwaves but a really big magnetic field that penetrates the crust and introduces eddy currents.

I agree with John here.  I think that a large moon causes rock tides that produce heat and help keep faults active.  Both of which help keep volcanos perculating.  Pity it is such a monsterously, difficult, huge job to give Mars a decent sized moon.

No big moons except for Jupiter's. its just too expensive to go that route... <ed.  bringing a giant moon for Mars>...
More easily you could just steer a big asteroid or comet into Mars, the shock and heat would release a heck of a lot of water that should bolster the atmosphere with enough water vapor to hold onto some daytime heat and even transport heat around MArs. But you might need dozens or more comets to do anything signifficant. any gearheads out there with the calcs?

...

Yes, mars does have a
a molten core, Mars radioactive decay should be slowing down much like Earth's since there is no resupply of these elements...

Cindy found another article...

*Okay, I've scrolled through the past 2 pages in this thread.  Am posting a new article from space.com (I don't see this particular article is yet posted):

Air leaks from Mars via planet's tail

Hopefully contains some additional/new info for New Mars readers.

"About 1 kilogram of mass is lost to space every second, Lundin told SPACE.com. That would be equal to 2.2 pounds of material if weighed on Earth."

--Cindy

The posts went a bit off topic discussing if the Methane in Mars atmosphere might have been created by non-biological systems in the mantle.  Is there oil on Mars?

As Karov noted, ... theres actually quite a good argument that most of the petroleum resereves on Earth were formed inorganically via chemical reactions in the mantle... more about oil on Mars

So oil reserves could theoretically still exist on a sterile Mars, and I would suspect that small amounts of it would have bubbled to the surface in certain places at some time in Mars' history, and if so, would it leave some detectable sign observable from orbit?

im thinking that any oil at the surface is likely to be buried or altered in some way, but it also might eventually get eroded by blowing sand but im wondering whether or not it could in any way get altered and reduced in particle size and 'mixed in' with the dust so that very sensitive instruments might detect its trace amounts?[/color]

Karov points out that if hydrocarbon reserves exist on Mars it will make the job of colonists easier.  (Long chain hydrocarbons are endlessly useful quite apart from the fact that they burn in an oxygen atmosphere.


Another article by atomoid (I've edited it a bit)...

theres a pretty good and relatively recent (2000) pdf paper by John McGowan on oil and natural gas on Mars he also talks about the need for a trace gas sensor.
See, for the article in *.pdf format.

Karov gives us this post on salts and water on Mars.  (Again a bit off topic.)
His posts are so large that I am just grabbing his references.

http://www.spacedaily.com/news/mars-wat … -html.html

& how to terraform Mars quickly:

http://www.paulbirch.net/TerraformingMarsQuickly.zip

In addition he says that this is further evidence that tiny worlds with cheap and simple methods can be terraformed. 

The origional posts are still there, but this is a summary of what I found most interesting with my comments.


Warm regards, Rick.

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#2 2007-04-11 03:05:25

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: How Quickly Does Mars Lose Air?

karov has wonderful numbers on this stuff, but my take-away was that the lack of a large magnetosphere is a problem, but even if you create an artificial one (by building a superconductor around the equator), the low gravity will mean that a 1000 mbar Martian atmosphere will be reduced back to 10 mbar by natural processes over 100,000 years, so there has to be an ongoing program of iceteroid disassembly and injection.  However, if you can do the terraform in the first place, the maintenance program is probably not going to be a challenge.

There was also a discussion about creating a Lunar atmosphere.  The 3 sigma loss rate was closer to 100 years, but there was all sorts of interesting speculation about how you could knock that up a couple of orders of magnitude.  Quite inspiring.


Fan of Red Oasis

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#3 2007-04-12 12:21:02

karov
Member
From: Bulgaria
Registered: 2004-06-03
Posts: 953

Re: How Quickly Does Mars Lose Air?

Why superconducting cable for planetary scale magfield?

graphene electronic waveguide or other means of balistic movement of charges, orbital ring accelerator, and the best candidate:

http://adsabs.harvard.edu/abs/2007physics...1058B

plasma cord ring. Pump in it as much electricity as needed for 10fold stronger than terran magnetosphere.

In weaker gravity just make the magnetosphere more powerfull. Shape it in more complex form to activelly create magnetic trap, decelerating and returning trying to escape iones, point the "channeling in" pole toward the Sun / the local star / to suck in hydrogen -- thus also providing the necessary operational power... Very often we don`t need too HiTech approach, very often the techs used for centuries, scaled up or down give us what we need.

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#4 2007-04-13 02:49:05

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: How Quickly Does Mars Lose Air?

Awesome!  Wow, I hope that can happen.  I think he is a little too cavalier with respect to stability problems however (it seems to me to be the central problem).  Even if a rotating cord can stabilize the structure, how do you make sure your multi-million kilometer plasma cord rotates at 0.1 m/s?  Can it really be controlled reliably with some sort of driving force from one end?  But maybe you just need some sort of periodic reinforcement. 

I wonder how fast you could deploy it?  Some fraction of c?


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#5 2007-04-13 16:57:02

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: How Quickly Does Mars Lose Air?

Karov,

Or even a few smaller cable rings designed to combine fields with neighbor cables?
Lots of control that way.

No need to make a cable runs around an entire planet when short run cables can combine mag fields, or channel them to collect hydrogen and repel the rest.

Shorter 100km or 50 km cables are pretty common tech and involve very small power loss so good conversion to mag field.

That is real low tech smile


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#6 2007-04-15 02:21:52

karov
Member
From: Bulgaria
Registered: 2004-06-03
Posts: 953

Re: How Quickly Does Mars Lose Air?

nickname,
I agree. Smaller cables - LoTech. Simpler - more stable ( unless the higher complexity doesn`t possesses homeoresistant properties, with negative feedback loops with the harming factor - utilizing its energy - but this is too meta-theoretical...) . You are right that it is not necessary the cables to run around the whole place. ( unless they aren`t bolonkin`s plasma cords encyrcling the planet into literally cage of power lines givin` the necessary topologies as effect -- the plasma cords could run out of the moons , from satelites ( the cords as you see weight only kilograms!), or / and to end into aerostats hovering really high in the martian atmosphere above the polar and other areas.) Magnetism thus could be easily controled via adjusting the current intensity...
My math abilities are not too well, but I think with sich magnetic atmosphere confinement, really LITTLE bodies could be centered in magnetic atmospheric sacks / bubbles / confinement. I wonder what`s the lowest limit for the central mass , if any. EM is trillions and trillions asnd trillions times better interacting weith our matter than gravity, so with locally abundant energy resources, the job seems to be possible -- solar EM radiation and solar particle wind must give enough power to hold human grade atmosphere around smaller objects...

2. From the other hand the LoTech approach should be considered deeper, too.

Why to put equatorial cable rings or orbital ones? Why to center the magnetosphere on the planet`s center?

Saturn`s non-excentric magnetosphere protecs perfectly Titan, making it one of the few really radiationless environments in SolSys. With the same success the source of protecting planeto-magnetism could orbit the central body, instead of the usefull real estate to orbit so excessivelly massive magnet.

I mean s.t. like this:

a) http://en.wikipedia.org/wiki/M-type_asteroid make about 8% of all the Main belt population. Regarding from the new optical and statistical data it hints that the number of Inner system small bodies is 4-5 times than we accept now. i.e. 4-5 000 >1km NEAs and 4-5 million Main Belters + 4-5 million Jupter trojans& hildas... but this is another question of debate... the point is we have even at the lower nowaday number estimation at least 80-100 000 metalic asteroids close to Mars with diameter more than 1 km.

b) now look at this: http://en.wikipedia.org/wiki/216_Kleopatra

216 Kleopatra is too huge to be relocated easily, but if famous enough and has the right shape and composition for the proposed bellow design. Much smaller ( 2-3 km long, 0.5 km wide?) elongated iron-nikel body would suffice.

c) Put one such in several dozens of thousands of km high martian orbit - circular or eliptic, each possesses some advantages.

d) Spool a ( golden? aluminum? cooper? allow?) cable tightly around it to form a http://en.wikipedia.org/wiki/Electromagnet =- the metal asteroidal "bar" as electromagnet`s "core" of course.

e) Power ( solar energy ) it with as much TW as it can stand. Regulate the power to mach the biggest profit at any orbital position ...

Note: Thus, NOT necessary to reheat the martian interior and to commit other activities with so little efficiency. Even it is better to have the iron martian core in its present state -- it could be secondarily excited by the orbiting electromagnet.

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#7 2007-04-15 06:38:05

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: How Quickly Does Mars Lose Air?

karov,

Nice to see you back on the board smile

Yeah low tech is the way to go if possible on most projects.

The multiple rings have plusses and minuses, but no more difficult than trying to control very big rings.
A little more difficult to coordinate all the smaller rings into a useful mag field than one big for sure.

As you point out Saturn does a nice job of protecting Titan so it's more of a question of where is the best place to put a manmade mag field.
In deep space at focus or close to the planet?

I've always wondered about this as a possible for a planetary mag field.

Orbit a nickel/iron asteroid, pulverize it into a metal dust ring, then charge that as a mag field.
Has some pretty serious tech probs, but if you could charge it from space it might be an ideal mag field.

Re heating the core of mars like you say is a very inefficient process, probably not worth the effort if we just need a magnetic field.

If we really needed a heated core for some place, i guess i would orbit a large kb in a really sloppy orbit around a moon or planet to add gravitational flexing.
Seems impractical though and quite dangerous in the inner solar system as re heating a core requires a pretty decent sized partner at close orbit.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#8 2007-04-15 09:39:18

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: How Quickly Does Mars Lose Air?

Why superconducting cable for planetary scale magfield?

The nice thing about a superconducting structure though, is that rather than just dissipating the terrawatts (i^2*R -> heat, light, etc), it can store them - act like a planetary power reservoir while providing the magnetic field.  I think that's meaningful, even at terraforming scales.

Superconductors aren't that much extra effort outside the cryogenics.  One of the interesting aspects of the orbiting asteroid-electromagnet idea is that you could organize free cryogenics pretty easily, especially since you want to suck up all the sunlight in the locality anyway to power-up the device.  I think you'd want the orbit to be as regular as possible though (geostationary?) to minimize interference with ordinary electronics.


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#9 2007-04-17 05:15:16

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: How Quickly Does Mars Lose Air?

noosfractal,

The pulverized metal asteroid as the coil sure make construction a pretty simple process.
It also makes charging it with any control a pretty difficult process.

I wonder if just having a metal dust ring spinning around the planet would make its own mag field?
Should be a differential energy between the ring and planet and solar activity.
Not much control of what kind of field it makes though without some pretty serious tech additions.

Without some sort of control it is sure to be an electronics nightmare near the planet.

Long term and low tech solution though.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#10 2007-05-08 23:03:07

RickSmith
Member
From: Vancouver B.C.
Registered: 2007-02-17
Posts: 244

Re: How Quickly Does Mars Lose Air?

noosfractal,
I wonder if just having a metal dust ring spinning around the planet would make its own mag field?

If you put a charge on the dust it will create a magnetic field.

This magnetic field will accelerate your dust and it soon won't be in orbit anymore.

Rick

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#11 2007-05-21 15:58:31

Spatula
Member
From: Raleigh, NC
Registered: 2007-05-03
Posts: 68

Re: How Quickly Does Mars Lose Air?

Atomoid references the 2004 July / August issue of the Planetary Report which discusses how needed a magnetic field is to keep an atmosphere. Some of the main points...

- For a 1 atm pressure atmosphere you need more gas (because the lower gravity does not compress it as much). This thicker atm. actually gives more radiation protection with out a magnetic field than Earth does with it.

- The article says that 2 m of water was lost over 4 billion years. (This is less than the 14 to 34 meters quoted above.) A thicker atm. won't erode faster than the current one, so if we give Mars a new atm. it would last a very long time. e.g. billions of years.

- The article suggests that the water has not been lost but is frozen under the surface. It then talks about McKay / Zubrins terriforming idea.

This is exactly what I've been saying. A thick atmosphere will not have the high escape rate that a thin one has under the same gravity, due to the real gas law. What Mars lost over billions of years could take trillions if it had the atmospheric density required to create 1 bar of pressure. An Earth-like atmosphere with a distinct ionosphere layer will be more than enough to protect from the Sun's high frequency radiation. This occurs at Earth's poles, where the magnetosphere is weak or nonexistant. It occurs when Earth's magnetosphere enters a dormant phase for hundreds of thousands of years. Not having a dynamo is not a problem.

Now, not having geological activity except for the occasional fumarole or hot spring could indeed be a problem for Mars in the long term. We'll have to see.

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#12 2007-05-21 17:26:02

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: How Quickly Does Mars Lose Air?

RickSmith,

Wouldn't the iron dust just all clump together in a thin ring?
Once we add a charge iron should be pulled together.

An acceleration of the iron ring might be a plus.
If it accelerates we can start it in low orbit and move it into a higher one for free.(sort of free)

Hmmm! wonder if that same idea would work on earth?
Bet you can guess what I'm thinking smile
Cheap no fuel orbital changes for metal crafts.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#13 2007-07-06 17:01:27

firstcolonist
Member
From: White Plains, New York
Registered: 2007-06-14
Posts: 1

Re: How Quickly Does Mars Lose Air?

Is it possible that we could insert a dense non-radiactive material into the core that would increase the planets gravitational pull to keep the oxygen in the atmosphere. Also, couldn't it be possible to find or drill a hole into the core of mars and from that point have a nuke with a hyper-dense shell that would stay intact until the inner core at which point it would explode and start the cores rotating to create a magnetosphere. I would like to know if either of these optiopns is viable to begin teraaformation.

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#14 2007-07-07 02:15:55

m1omg
Member
From: Q Continuum
Registered: 2007-07-03
Posts: 70

Re: How Quickly Does Mars Lose Air?

Is it possible that we could insert a dense non-radiactive material into the core that would increase the planets gravitational pull to keep the oxygen in the atmosphere. Also, couldn't it be possible to find or drill a hole into the core of mars and from that point have a nuke with a hyper-dense shell that would stay intact until the inner core at which point it would explode and start the cores rotating to create a magnetosphere. I would like to know if either of these optiopns is viable to begin teraaformation.

That is a nonsense from film the Core.
Nukes are weak here.
And Mars can retain its oxygen.
Even 1000 nukes will not produce any effect.
Atmosphere is leaking after bíllions of years not days.

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#15 2007-07-07 02:23:16

m1omg
Member
From: Q Continuum
Registered: 2007-07-03
Posts: 70

Re: How Quickly Does Mars Lose Air?

Atomoid references the 2004 July / August issue of the Planetary Report which discusses how needed a magnetic field is to keep an atmosphere. Some of the main points...

- For a 1 atm pressure atmosphere you need more gas (because the lower gravity does not compress it as much). This thicker atm. actually gives more radiation protection with out a magnetic field than Earth does with it.

- The article says that 2 m of water was lost over 4 billion years. (This is less than the 14 to 34 meters quoted above.) A thicker atm. won't erode faster than the current one, so if we give Mars a new atm. it would last a very long time. e.g. billions of years.

- The article suggests that the water has not been lost but is frozen under the surface. It then talks about McKay / Zubrins terriforming idea.

This is exactly what I've been saying. A thick atmosphere will not have the high escape rate that a thin one has under the same gravity, due to the real gas law. What Mars lost over billions of years could take trillions if it had the atmospheric density required to create 1 bar of pressure. An Earth-like atmosphere with a distinct ionosphere layer will be more than enough to protect from the Sun's high frequency radiation. This occurs at Earth's poles, where the magnetosphere is weak or nonexistant. It occurs when Earth's magnetosphere enters a dormant phase for hundreds of thousands of years. Not having a dynamo is not a problem.

Now, not having geological activity except for the occasional fumarole or hot spring could indeed be a problem for Mars in the long term. We'll have to see.

Exactly.
With a dynamo particles are only crashed into polar regions.

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#16 2007-07-18 02:08:24

RickSmith
Member
From: Vancouver B.C.
Registered: 2007-02-17
Posts: 244

Re: How Quickly Does Mars Lose Air?

Rick,

Wouldn't the iron dust just all clump together in a thin ring?
Once we add a charge iron should be pulled together.

An acceleration of the iron ring might be a plus.
If it accelerates we can start it in low orbit and move it into a higher one for free.(sort of free)

The question was, do we need a superconducting ring.  Nickname suggested that we put a charge on a ring of orbiting iron dust and use that to give the planet a charge.


OK, let us say that we have a speck of iron with a negative electric charge rotating west to east around Mars' equator.  By the right hand rule it produces a magnetic field pointing north.  So an entire ring of such particles effectively gives Mars an magnetic field like Earth's, with field lines coming from the north pole and sweeping around to the south.

Each of these particles has a negative electric field so they will repeal each other.  How do you keep them from spinning off right out of orbit?  Ignore this problem for now.

The magnetic field all of these creates interacts with the solar wind, creating a bow shock, etc.  This accelerates the charged particles in the solar wind.  However the accelerating solar wind ALSO accelerates the charged iron dust via magnetic fields.

During northern summer, a disproportionate number of the solar charges will flow over the north pole.  This will accelerate the iron dust to the west, deorbiting it.  In the southern summer, the particles will be kicked into higher orbits.  However the majority of this acceleration is from the sun facing side so the orbit will become more and more elliptical.  As the orbit becomes very long, the particles will entangle with the solar wind, start spiraling along the field lines and be stripped away.


If you want to create an artificial magnetic field, keep the rotating charges on the ground.  Then the acceleration given to the particles can be transfered into the giant momentum bank of the planet.


However there are a couple final things to keep in mind.

1) Sputtering of the solar wind (which strips off atmosphere) is VERY slow.  One kilometer sized asteriod will provide many millions of years of volatiles.  Getting one is far less effort than building a superconducting ring.  (Also the magnetic ring is unlikely to last millions of years.  HUMANS are unlikely to last millions of years...)

2) The Martian atmosphere (if it is put up to one atmosphere) is much thicker than Earth's because Mars has a greater scale height.  So much so that it provides more radiation protection from solar flares than the Earth's atmosphere plus our magnetic field.  (This result was from the summary post at the top of the article.)

So I don't see this as a pressing problem for terraformers.

Warm regards, Rick.

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#17 2007-09-02 12:09:33

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: How Quickly Does Mars Lose Air?

RickSmith wrote:

1) Sputtering of the solar wind (which strips off atmosphere) is VERY slow.  One kilometer sized asteriod will provide many millions of years of volatiles.  Getting one is far less effort than building a superconducting ring.  (Also the magnetic ring is unlikely to last millions of years.  HUMANS are unlikely to last millions of years...)

Unless we consider relativistic time travel into the future. A number of throw back Homo Sapiens could be visiting the Solar System millions of years into the future after conducting extensive galactic explorations in their starships.

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#18 2008-03-09 04:55:09

RickSmith
Member
From: Vancouver B.C.
Registered: 2007-02-17
Posts: 244

Re: How Quickly Does Mars Lose Air?

...
This is exactly what I've been saying. A thick atmosphere will not have the high escape rate that a thin one has under the same gravity, due to the real gas law. What Mars lost over billions of years could take trillions if it had the atmospheric density required to create 1 bar of pressure. ...

Hi Spatula, everyone.
  I was rereading some old post and saw Spatula's comments above.

  The Ideal gas law is:

    PV = nRT

where
P is the absolute pressure,
V is the volume of the vessel,
n is the number of moles of gas,
R is the universal gas constant,  (R =  8.314472   J·mol−1·K−1)
T is the absolute temperature (degrees K).

(The ideal gas law assumes that gas molecules bounce freely off of each other.  Real gases have slight molecular forces but these are very, very small, the ideal gas law works very well under a wide set of circumstances.)

Anyway, I have a question Spatula, why do you say that a thick atmosphere would lose mass to sputtering more slowly.  At the edge of space the atmosphere will be equally thin and have a considerably larger area so I would assume that the (slow) sputtering would be faster, not slower.  Considering the Ideal Gas Law, I don't see any reason the rate would increase with the thicker atmosphere.

Warm regards, Rick.

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