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Giving Mars a magnetic field

  1. Aug 22, 2012 #1
    In my opinion, any attempt to colonise Mars would require a sustainable atmosphere. Without a magnetic field; This atmosphere will quickly be stripped away by solar winds.

    Now if we were to "Build" a large enough moon orbiting Mars by towing asteroids into Martian orbit and allowing accretion to form a moon large enough to cause tidal effects that would increase the core temperature of Mars then will it not be possible to "wake" not only the "dynamo" effect but volcanism as well. This will result in conditions more suitable for long term colonisation.

    I know that it will require a hell of a lot of mass in asteroids but Rome was not built in a day neither.
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  3. Aug 22, 2012 #2

    Simon Bridge

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    There are a lot of opinions about what would be needed and what not.

    Your proposal would not just require a lot of mass, time, and energy ... it would require so much that it would need a colony as well.

    However - I don't see a question in there.
  4. Aug 22, 2012 #3
    Yes you are right; My question is: "What mass must the moon have in order to cause enough tidal force to increase the core temperature of Mars to the point where a magnetic field will be created"?
  5. Aug 22, 2012 #4

    Simon Bridge

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    You want to rely on tidal forces to restart the dynamo in Mars?
    I did a bit of reading around just to check, and the trick is to create a temperature differential and rotate the core.

    Mars' core is expected to be Iron-sulphide, which has a lower melting point than straight Fe ... so it may already be molten. One of the models for the snuffing of Mars' planetary-magnetic dynamo is that too much heating occurred during the bombardment phase. So I'd imagine that introducing tidal squeezing to heat the planet would be ticklishly precise... too much as ineffective as too little.

    Then, of course, a stronger magnetic field may make plasmoids more likely - just making the atmosphere loss worse rather than better.

    As for how much - not enough info. We need to know more about the interior composition. I'm sure someone's done the math for, say, Io - so tidal heating models will exist.
  6. Aug 22, 2012 #5


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  7. Aug 22, 2012 #6
    We just have to create a liquid mantle, several thousand atomic bombs detonated deep within the crust ought to do the trick.
  8. Aug 22, 2012 #7

    Simon Bridge

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    How about getting two large bodies to orbit their common com at the Mars orbit?
  9. Aug 23, 2012 #8
    This is a fun Fermi problem, but I think if you work out the numbers, you be surprised at how tiny and insignificant a few thousand atomic bombs are.
  10. Aug 23, 2012 #9
    Wow, you're right. I did a rough estimate and it would take on the order of a hundered billion 50 megaton bombs to melt Mars' crust. I think we're going to need antimatter weapons if we're going to take the liquifaction approach.
  11. Aug 23, 2012 #10
    Hmm! perhaps a comet or asteroid impact may produce that kind of energy? Maybe even sequential strikes by many 1+ kilometre sized objects?

    Another way would be to send from the asteroid belt hundreds of thousands of asteroids to impact with Mars and thus increase its mass resulting in thermal increase of the mantle due to energy released from the impacts but also from the added compression due to added mass?

    Oh if only Venus was where Mars is and Mars where Venus is. Shame really! Now we have to do some serious astroengineering if we are to ever make Mars habitable!
  12. Aug 23, 2012 #11


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    Waving our science fiction wand and proposing this is done have you worked out how long it would take for the surface to cool and become solid with a reasonable temperature (and tectonic activity)?
  13. Aug 23, 2012 #12
    Wouldn't it be easier to create a magnetic field on the surface? Possibly with some massive magnets? Either way, we are really good at generating electricity, so perhaps we can leverage this to induce enough magnetism to protect the planet. I think I read somewhere that the actual strength of the magnetic field around earth isn't that strong. I'm not sure if I misunderstood, but either way it seems more cost efficient to build field generators on the surface than mess with the core. Plus, the concept of smashing asteroids and comets into Mars has major problems when it comes to Earth's safety. Not only would you potentially eject hazardous degree into space that could make its way to Earth, but you would be perturbing the structure of the asteroid belt in ways that could fling material into the inner solar system.
  14. Aug 23, 2012 #13
    You wouldn't melt the entire crust, just up to a certain depth. I don't think tectonics is necessary for a magnetic field.

    That's an exellent suggestion! :) Creative! I like it. We just take a few nuclear powerplants and make a giant grid of electromagnets to protect the planet. That could even work here on earth to protect our satellites from solar flares.
  15. Aug 23, 2012 #14
    Geez. Might be easier to take advantage of the slightly chaotic nature of the Solar System to get Mars and Venus to trade places. It could take a billion years, though. It might take a million years just to fill out the environmental impact form.
  16. Aug 24, 2012 #15
    :rofl: :uhh: and all these tongues in cheek in a serious forum?? I guess it can be moved to SF next week.
  17. Aug 24, 2012 #16

    Simon Bridge

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    My immediate picture was of wrapping Mars in wire for a big (iron core!) solenoid.

    I could even imagine someone trying it ... the trick would be locating the owners to get consent: something the ethics committee will probably insist on. Since ecological impact is the whole point - that would be a hefty document ... thought the standard templates will be quick to fill out:
    Impact on waterways and wetlands - none.
    Impact on local indigenous population - none.

    I found a https://www.amazon.com/Legal-Daisy-Spacing-Official-Improvements/dp/0394549287 of the kinds of planetary improvements that are likely to be approved.
    Last edited by a moderator: May 6, 2017
  18. Sep 5, 2012 #17
    You know venus has an atmosphere and no magnetic field. Does the magnetic field help to retain certain gasses, or is it there for cosmic ray shielding?
  19. Sep 5, 2012 #18
    Venus has no magnetic field, as you suggest, but 1) it is much larger than Mars, which allowed it to retain a very thick atmosphere comparatively, AND 2) it experienced an extreme amount of vulcanism which released tons of CO2 into the atmosphere in addition to whatever atmosphere was already there. Those two factors allowed Venus to have such a thick atmosphere that the solar wind barely makes a dent in it.
  20. Sep 9, 2012 #19
    I'm confused. I thought that the combination of large mass and strong magnetic field allowed Earth to mostly retain its atmosphere. Mars, being less massive and having a weak magnetic field, had its early atmosphere stripped [science.nasa.gov]. But then why does Venus (with no appreciable magnetic field) have the ultra thick atmosphere? Shouldn't it have been eroded over the billions of years? Is it because Venus is massive enough to hold on to its gases? Or is the atmosphere being replenished by volcanoes?
  21. Sep 9, 2012 #20
    Venus does have substantial atmospheric loss. But it's atmosphere is 90 times as dense as the Earth's, so it will take a long time for it to be completely stripped away. I dont think there is much active vulcanism adding more to it. Also, and this is worth mentioning, Venus' atmosphere has high ionization in upper atmosphere from the solar wind itself that protects deep penetration. See the following page:

    Last edited: Sep 9, 2012
  22. May 24, 2013 #21
    I don't think it would be too hard to "restart" Mars core and regenerate that protective magnetic field. All you need is something big enough to orbit it; Jupiter has enough moons already, so I don't think it would miss one. This new Martian moon would do three things:

    1) It would create tidal forces, which would tug on the mantle and core, creating heat from the friction of the rocks flexing and scraping against each other. This would provide and help maintain the heat needed to keep the iron core molten, which is key to producing a strong magnetic field. (This is what happens to the moon Io as it orbits Jupiter.)

    2) Since the crust and mantle would be closer to the Martian Moon, it would affect their rotational speeds more severely than the core's. This would cause the iron core to spin at a different speed than the rest of the planet, thus recreating the ancient dynamo and magnetic field. (This is what happened to the Earth when the Moon was formed.)

    3) As with Earth and it's axis, Mars axis would become a much more stable. With the Moon, Earth would become very wobbly and would tilt much more extremely and irradically. Currently, without a moon, Mars is very wobbly on its axis, which would could lead to sever climate swings if it were ever teraformed. With a Martian moon, it wouldn't wobbly so badly, allowing for a more stable environment to be colonized by life.

    So, there you have it: all you need to do is send a powerful rocket to one of Jupiter's moons, nudge and aim it into an increasingly elliptical orbit around Jupiter until it final flies off (like swinging your feet on a swing; if you time it just right, you just need a little effort to really get going) towards Mars, steer it into an orbit around it, and BAM! you just got yourself a brand new magnetic shielded planet ready to be colonized!

    (And if you don't want to remove one of Jupiter's precious moons, no problem: there is an asteroid belt nearby just waiting for you to pick and choose what left-over asteroids you want to smash and bash together to make a new moon!)
  23. May 24, 2013 #22

    Simon Bridge

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    That's an interesting definition of "not too hard" ... crunch the numbers and write it up ;)
    How big-a tidal stress would you need from the new moon to provide a molten subsurface?
    Note: you may want a number of moons to get a tight-enough differential.

    While we are thinking on this scale - how about giving the moon a large electric charge (say, by collecting cosmic rays) and putting it in a rapid orbit?
  24. Mar 31, 2015 #23
    If you took an object about the size of Ceres (or Ceres itself) and placed it into orbit above Mars at 17,700 Km, then it would have the same tidal effect as Luna has on Earth (also, it would look just as big). Though that would take a lot of time and energy (not to mention, money).
  25. Nov 7, 2015 #24
    What about using space tethers, descended from orbit at the poles, to add charge to the core? Would it not begin to rotate as it heated?
  26. Nov 7, 2015 #25

    Simon Bridge

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    Welcome to PF,
    Have you worked out the numbers?
    Where does the charge come from?
    Why would the charge go only to the core?
    How would that heat the core?
    Would delivery to just the poles heat just the poles?
    What rate of heating would you get by this method?
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