I know terraforming Mars has been a topic of discussion for a long time. One of the larger obstacles is the planet's weak magnetic field, which if I understand correctly is integral to containing an atmosphere and deflecting harmful solar radiation.

Could this problem be solved by deploying a network of satellites that contain large superconducting electromagnets that would work together to create the needed electromagnetic field so that the planet could be terraformed?


closed as primarily opinion-based by kim holder, Brian Tompsett - 汤莱恩, Rory Alsop, TildalWave Jan 17 '16 at 17:53

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    $\begingroup$ Attempting to rephrase to extract assumptions: "Is the long-term cost of deploying, powering and maintaining an artificial magnetic field of approximately the strength of that of the Earth around Mars sufficiently low to ever be economical?" (I'd guess no. But this is a really really big question.) $\endgroup$ – Anko Jan 16 '16 at 1:43
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    $\begingroup$ I'm guessing any magnetic field strong enough to provide what you need would also cause adverse effects on the satellites' orbits. $\endgroup$ – Brian Lynch Jan 16 '16 at 1:51
  • $\begingroup$ You may wish to take a gander at space.stackexchange.com/questions/2423/… $\endgroup$ – Everyone Jan 17 '16 at 16:18

If you are able to terraform Mars in some reasonable amount of time, let's say in 100 years, then you don't need a magnetic field. Just do whatever you did to terraform the planet, but at one billionth of that rate, in order to counter the loss of atmosphere to the solar wind. Or don't even bother at all, leaving the problem to your great1000000-grandchildren to deal with. It's a very slow process, taking tens of millions of years to even have a noticeable loss.


One of the larger obstacles is the planet's weak magnetic field, which if I understand correctly is integral to containing an atmosphere and deflecting harmful solar radiation.

That is far from one of the larger obstacles. That is, per Mark Adler's answer, a problem for our children's children's ... children to solve. The larger obstacles are

  • How do we terraform Mars?
    There are lots of science fiction stories about terraforming Mars. For now, the concept of terraforming Mars is just that, science fiction. Sans fiction, we don't know how to do that.
  • Can we afford to terraform Mars?
    Terraforming Mars will cost lots and lots and lots of money. There are perhaps better ways to spend all of the money than spending it on making Mars habitable.
  • Do we want to terraform Mars?
    Sending a small number of people to Mars would fall under the category of "we do this not because it is easy, but because it is hard." Terraforming Mars would fall under the category of the much larger question, "is this profitable?"
  • What if Mars still harbors life?
    If this is the case, I'd argue that terraforming Mars would make each of us stuck on the Earth many times worse than the very worst despots of all of the previous millennia.
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    $\begingroup$ If Mars harbors any life, it's almost certainly microbial, and it's hardly despotic to eradicate it (though obviously we ought to preserve it for science). $\endgroup$ – Russell Borogove Jan 16 '16 at 22:01
  • $\begingroup$ If Mars still contains life than that life is a remnant of a time when the conditions were right for life on Mars. Returning the planet to those initial conditions would help, not hinder the life on Mars. Leaving it to wither and die would be much curler than terraforming the planet. Life cannot flourish under the current conditions on Mars and if you think it will fair better when the sun grows older and hotter, think again; Mars has no protection from solar radiation. $\endgroup$ – memory of a dream Sep 17 '18 at 10:36
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    $\begingroup$ You've misspelled "hard" in "... but because it is hard". Should be spelled "haad" :) $\endgroup$ – Innocent Bystander Oct 30 '18 at 21:46

Let's use Earth's magnetic field as a starting point. If we wanted to replicate that using magnetic iron, we'd need $10^{20}$ kg of iron, give or take a few orders of magnitude.
Supercondicting magnets can be $10^5$ times stronger than magnetic iron.
So we'd need to install $10^{15}$ kg of magnets on Mars, plus their power sources. Again, give or take a few orders of magnitude.

So far we've launched something like $10^6$ kg into orbit. The biggest construction projects in Earth weigh $10^9$ kg. You're proposing a project a million times larger. You can see how far from possible this is.

  • $\begingroup$ "plus their power sources". This part could be manageable with supoerconducting magnets. No need to keep pouring in power. Keeping them cold enough (with current material) might be a challenge though. When mars blocks the sun it might be cold enough, but when facing the sun we would need some serious isolation. $\endgroup$ – Hennes Jan 16 '16 at 14:56

To address your actual question, it might be extremely hard to do that. Individual satellites would make individual dipole fields. Even if you deploy a million satellites in low orbit, thats still >40 square kilometers for each satellite to try to affect. It would be mostly holes.

Maybe something upstream at Lagrange L1 has slightly better numbers?

...but the other answers are the best answers - it won't matter for a zillion years and there are other more pressing questions about terraforming Mars in the first place.


The fairly obvious answer is not to use individual satellites. Instead, create an orbital ring. It would be about 20.000 kilometer long. This isn't an areostationary orbit precisely because the ring is intended to rotate. Otherwise, the sunny side would overheat. It needs to rotate to balance the temperature.


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