I guess the title says it all. How big of an electromagnet would you need to generate a magnetic field the same as Earth's? Like, what kind of amperes are we talking here? (Assuming a hypothetical superconducting magnet, of course.)


You are in luck, since Osamu Motojima and Nagato Yanagi have already calculated it for you in their report Feasibility of Artificial Geomagnetic Field Generation by a Superconducting Ring Network. They conclude that producing 10% of the current field is feasible using "12 latitudinal high-temperature superconducting rings, each carrying 6.4 MA current with a modest 1 GW of power requirement".

(The motivation for the report is the concern about the consequences of Earth losing its field during a geomagnetic reversal, but it doesn't look like those are particularly bad.)

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    $\begingroup$ Is this linear, i.e. can we extrapolate this to 100% of the current field? $\endgroup$ – Paŭlo Ebermann Apr 27 '19 at 12:40
  • $\begingroup$ I think so, although you may have to make the rings bigger to keep things safely under the superconduction limits. $\endgroup$ – Anders Sandberg Apr 27 '19 at 15:24
  • $\begingroup$ Also, if mankind is ever going to terraform Mars, we definitely need an equatorial magnetizer! ;-) $\endgroup$ – cmaster - reinstate monica Apr 27 '19 at 18:42
  • $\begingroup$ @cmaster - One can put coils in the L1 point to deflect the solar wind at Mars: medium.com/our-space/… $\endgroup$ – Anders Sandberg Apr 27 '19 at 19:55
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    $\begingroup$ @beppe9000 - The game is the boardgame Terraforming Mars. $\endgroup$ – Anders Sandberg Apr 28 '19 at 2:45

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