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I Guarding Mars' atmosphere with a magnetic shield

  1. Mar 6, 2017 #1
    NASA scientists have proposed a magnetic shield that would sit at the L1 Lagrange Point beyond the planet, creating an artificial magnetosphere that would deflect solar winds and incoming radiation... Let's discuss thoughts and implications, engineering problems, etc. in such a formidable task. Can we as humans do this? We are not yet a Type 1 civilization yet?
     
  2. jcsd
  3. Mar 6, 2017 #2
    I'm not sure I can see this being feasible. Several immediate issues I see...
    1) It will need to be HUGE
    2) It will need to overcome gravity
    3) It will need to coexist with the orbits of the moons
    4) It could potentially change the atmosphere of Mars (in a positive or negative way)
    5) If it malfunctions, then :oldsurprised:

    What are your thoughts on these issues?
     
  4. Mar 6, 2017 #3
    One concept being proposed uses magnetospheric plasma ionization, uses the fact that in a collisionless plasma the magnetic field is frozen in to the plasma. As the plasma expands outwards it will generate the necessary currents to carry the magnetic field with it. As this expanding plasma moves out work is done on it by the solar wind, and eventually the expansion stops when the pressure of the solar wind is balanced by the total (plasma and magnetic) pressure within the magnetosphere.

    Problem with this is generating the required plasma field sufficient to get the magnetic field started, energy required to induce this current, and structure/engineering much less the spacecraft/human activity to get all this off the ground... did I mention the funding required for this?

    Of course the object is to change the atmosphere of Mars, if it malfunctions the end result would be minimal to Earth/Moon since the distance of the experiment is negligible to our surrounding magnetosphere but perturbations in space might have some detrimental effects such as kicking one of many asteroids out of their normal orbits, etc.
     
  5. Mar 6, 2017 #4
    That's quite typical for planetary engeneering.

    Not in L1. But it will need to overcome the solar wind. That could be handled by adjusting the position in order to cancel the drag out by gravity. The drag could also be used to keep the shield it in it's unstable position.

    That shouldn't be a problem. Maybe the moons can provide the recources for the shiled. That will depend on the required materials, the composition of the moons and the available technology to mine and process the raw materials.

    The intended change of the atmosphere of Mars is the reason for this idea.

    Mars will be exposed to the solar wind again and the shield needs to be fixed or replaced.
     
  6. Mar 6, 2017 #5
    Please correct me if I take it wrong, but that thing would act as gigantic (bigger than planet-size)(magnetic) solar sail?
    Then what kind of propulsion would it need to keep it at L1 against the solar wind?
    I really don't think that we are ready to 'plan' on this...
     
  7. Mar 6, 2017 #6
    Well we haven't done something to a planet on this scale yet, so can we say it's typical?
    While this is certainly a good idea, it would probably be more efficient to just power the shield through Mars.
    Could this not be potentially harmful, though?
    $$$
     
  8. Mar 6, 2017 #7
    Yes.

    Of course it would be harmful for the original Martian biosphere (if there is somethig like that). But for humans the Martian atmosphere already is harmful. The purpose of terraforming is to make it less harmful for humans.
     
  9. Mar 6, 2017 #8
    Airborne plasma sounds pretty harmful. Maybe I'm wrong but it seems like this might not be worth all the money it would cost just to make the atmosphere a little less harmful.
     
  10. Mar 6, 2017 #9

    mfb

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    There is an earlier suggestion to produce an artificial magnetic field with superconducting coils at the surface - for Earth, but adaptable to Mars. Putting coils at L1 is an interesting approach as well.

    The Sun/Mars L1 point is 1,070,000 km away from Mars. This is far away from the tiny moons (Deimos 23,000 km, Phobos 9,400 km semi-major axis). They might be used for building materials, apart from that they are not relevant.

    The solar wind would lead to some force on the magnetic field, but this force is small compared to the radiation pressure a solar sail would experience. At 1 AU, it is typically 1-6 nPa, at 1.5 AU it is about half that. Multiplied by pi*(Mars radius)^2, we get 20 kN - 100 kN, maybe more if we want to shield a bit more.
    A superconducting coil would probably have a mass of at least a million tons. Pressure from solar wind would be a small, but not negligible contribution to the force balance. Just put it a bit closer to the Sun than L1.

    In space, and at 1.5 AU, a superconducting coil could be cooled passively. It would put itself into a circular shape itself as soon as current runs through it.
    I would expect the orientation of the coil to be stable, but a small rotation could be added if that is wrong. The position would be more challenging, as L1 is unstable. Maybe the interaction with the solar wind can be used.

    If it fails, Mars continues losing atmosphere at a tiny rate. Even a 100 year break in its operation wouldn't have notable effects. Which also means it makes no sense to start building something like this in the 21st century. This is something that could become interesting in thousands of years, if humans are still around then.
     
  11. Mar 6, 2017 #10
    As far as I understand there is no airborn plasma.

    Terraforming is completely outside any current economical possibilities. Therefore it makes no sense to discuss the economic aspects of such a project. Maybe future economies are not even based on money.
     
  12. Mar 6, 2017 #11
    That's what @infinitebubble seems to be talking about (unless I misunderstood his second post)
    Maybe its based off of chocolate :woot:
     
  13. Mar 6, 2017 #12
    I like the superconductor on the surface concept better. For one thing, if it fails, and there is some kind of civilization on Mars, the time it takes to fix it would be a lot faster than something a million Klicks from Mars unless there is some kind of repair city already in place there. I calculated a field of about 1 gauss could be made with a few turns of said superconductor carrying about 50,000 amps, not impossible. It would be even better if someone gets off their butt and develops room temp superconductors:)
     
    Last edited by a moderator: Mar 6, 2017
  14. Mar 6, 2017 #13
    Maybe you can be that someone :wink:
     
    Last edited by a moderator: Mar 6, 2017
  15. Mar 6, 2017 #14
    NASA has been doing experimental work since the early 2000's on Ion Plasma Magnetosphere technology and or research. What they've come up with is called M2P2 in terms of a Mini-Magnetospheric Plasma Propulsion but whose initial experimental work could be the precursor of a viable magnetic shield for Mars on a grander scale.

    Called a Helicon Plasma Generator which ionizes gaseous argon and helium with radio waves (all of which is locally obtained from the space medium) and generation of the radio waves is easily a feat we already master. Such energy could be obtained by massive solar photovoltaic or nuclear.
     
  16. Mar 6, 2017 #15
    Work is currently being done with 'graphene' or carbon nanotubes which may hold extreme promise on getting superconductivity at room temperatures or very close to it... we are decade or so from having this material.
     
  17. Mar 6, 2017 #16
    According to http://ffden-2.phys.uaf.edu/113.web.stuff/travis/what_is.html ...

    "The highest Tc reached at stardard pressure, to date, is 135 °K or -138 °C by a compound (HgBa2Ca2Cu3O8) that falls into a group of superconductors known as cuprate perovskites."
     
  18. Mar 6, 2017 #17
    To my understanding the plasma he is talking about is generated a million kilometers away from the atmosphere. And even if something goes wrong and the plasma hits the atmosphere it wouldn't cause any damage on the surface because it has a very low density.
     
  19. Mar 6, 2017 #18
    Okay I see now. What mechanism would keep the plasma in place up there, though? Or would it's low density account for that?
     
  20. Mar 7, 2017 #19
    Seems temporary. And vulnerable to a missile, if someone lacks patience.

    How much trouble in tossing a phone pole sized bar magnet very precisely (smart bomb) at the Poles of the Planet? How many would it take to magnetize the planet?

    Would't really matter where you set up the factory. Robots don't care. Phobos may be available.
     
  21. Mar 7, 2017 #20

    Al_

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    You mean Mars-temperature?
    In a thin atmosphere that averages, what -50 or something, a little bit of insulation might be all it needs...
     
  22. Mar 7, 2017 #21

    mfb

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    A phone pole sized magnet will have no effect. No realistic number of them will have any notable effect. You need something 10 orders of magnitude stronger, or something much larger. And you have to keep them there. You cannot "magnetize the planet".
    Insulation alone doesn't cool something to below the temperature of the environment.
     
  23. Mar 7, 2017 #22
    Regarding creating a magnetic field around Mars, Mars has an very weak magnetic field (approx. 40 times weaker than Earth's magnetic field) and is only found in the southern hemisphere. When Mar's core cooled long ago the magnetic field disappeared. This was detected by Viking and subsequent Mars landers on it's rocks. This field is way too weak and non-uniform to be able to protect the planet from the solar wind. For this reason we need to sheild the planet from the Sun's solar wind as a first order of business.

    One way may be to liquefy the outer core of Mars. Then Mar's own rotation would create a dynamo and generate a magnetic field much more similar to Earth’s core. This could be done using megaton nuclear bomb(s) which would be placed near the core. The thermonuclear bombs would have to release enough energy to liquify the core, quite a large amount of energy but would also introduce radioactivity which would render the Mars planet uninhabitable for sometime!

    Another scenario would be to electrify Mar's core and set it up like a dynamo using solar electricity (Terawatts'?) and start the core rotating... this would create the much needed magnetic field it would require to shield the solar wind.

    Suppose we somehow terraform Mars for habitation. We could warm it up and give it a similar atmosphere to Earth's and a 75-90% magnetic field to protect it from solar wind. Would the atmosphere stick around? Some studies indicate it would not hold any atmosphere enough to make it 'home' for humans.
     
    Last edited: Mar 7, 2017
  24. Mar 7, 2017 #23

    mfb

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    We don't have to. Atmospheric escape from the solar wind happens on a timescale of millions of years. It will be irrelevant over 100 years and still a tiny effect over thousands of years. It is pointless to try to solve a problem that might arise in tens of thousands of years with technology of the 21st century. It is nice to know that there is solution even with 21st century technology, but we can't expect people in thousands of years (if there are humans around) to use our primitive technology to solve the issue.
    "Quite a large amount" exceeds the total nuclear stockpile by some orders of magnitude.
    The fallout would be well contained inside Mars, and not an issue at the surface, but the whole idea is not viable anyway.
    It would slowly lose hydrogen from Jeans escape, but that is on an even longer timescale. I guess that loss could be countered by occasional water imports from the remaining solar system. But that is like trying to solve an issue in spaceflight with technology from the stone age. Even if you find a solution (stone as structural material in rockets?), it will look ridiculous once the problem actually comes up.
     
  25. Mar 13, 2017 #24
    Agreed with a necessary shield to protect the atmosphere but also against the radiations (or the ground and the resisting plants for food will be also radioactive..).

    Could it be possible and more practical to just extend the existing patches of magnetic field with a web of magnetized metal rods into the ground?
    Do you think that then the rotation of the planet could somehow charge it?
     
  26. Mar 14, 2017 #25

    mfb

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    Induced radioactivity (things getting radioactive from ionizing radiation) is completely negligible. It is relevant in nuclear reactors, but there the radiation dose is billions of times higher than in space.

    Magnetized metal rods would need an unreasonable amount of material. And the rotation of the planet wouldn't have any effect on that.
     
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