The answers to my latest question on restarting Mars core have finally convinced me; I have abandoned the concept of doing so. However, whilst morosely browsing other questions on giving Mars a magnetic field, I happened upon Ville Niemi’s answer to What would be best way to re-melt Mars' mantle and core to revive its magnetosphere.

In it, they propose building a pair of giant electromagnets, one at either pole, which together produce a magnetosphere. The system draws electric current from the planet itself; thermocouples buried deep beneath the surface convert geological heat into electricity by the thermoelectric effect.

Now, ordinarily, I would be opposed to putting an entire planet’s habitability on any kind of fallible, man-made generator, where all it takes is for some wiring to blow to render the whole planet uninhabitable. However, I am now seriously considering going with this idea, because:

A: unlike most ideas along these lines, this one does seem like it could work continuously with zero maintenance on a timespan of millions of years

B: I’ve lost Venus; I’m desperate.😭

So, my question is, in essence, how long could this system realistically last without maintenance, and what is the tech-level required of a civilisation to build it?

  • 3
    $\begingroup$ (1) Over a timespan of mere millions of years you don't need a magnetic field. Sure a magnetic field is nice to have so that magnetic compasses work and so on, but it is not necessary. A magnetic field is necessary only if you are interested in timespans of tens or hundreds of millions of years. (2) On human scales, a million years is an enormous time; the entire human history fits 200 times over in a million years. Making Mars habitable now is enough: forget about the magnetic field and just leave a note saying that air is consumable and needs replenising every million years or so. $\endgroup$
    – AlexP
    Feb 26 at 9:14
  • $\begingroup$ Thermoelectricity is very inefficient. It can turn about 1% of a flow of heat into electricity. Given that Mars' core is likely already rather cooler than Earth's, I really doubt you'll get enough power for a significant magnetic field. However, as others have said, this doesn't matter much. $\endgroup$ Feb 26 at 12:12
  • $\begingroup$ There are much better and surprisingly cheap proposals to generate a magnetic field for Mars. One uses the innermost of the Martian satellites and only needs a few GW of power. $\endgroup$
    – Avun Jahei
    Feb 26 at 13:50
  • $\begingroup$ VTC Needs more focus (one and only one question) and opinion-based (a million years? How should we know? The tech required for that is Clarkean Magic). What's the real problem? What's stopping you from using a perfectly reasonable scientifically-based solution, declaring your tech to be better-than-average, and moving forward with your worldbuilding and/or story? The 1989 Rockwell International Integrated Space Plan proved itself inaccurate after a mere ten years. You're asking for prophetic predictions. $\endgroup$
    – JBH
    Feb 27 at 0:55
  • $\begingroup$ BTW, that Integrated Space Plan's timeline was certainly optimistic, but the chart of technological progress should be your bible for developing your future tech. Start with the chart, see what kinds of interconnections they needed to achieve similar but more limited solutions, then build your solution on the pattern. $\endgroup$
    – JBH
    Feb 27 at 0:59

1 Answer 1


As you have been already told in the series of Venus questions, you are making giants out of ants with all these "problems" you are seeing.

First of all, if you manage to make Mars habitable, it won't go bad overnight just because a device stops working. It takes geological times to lose an atmosphere and an hydrosphere, and men don't live that long. You could have empires rise and fall before the planet starts feeling less hospitable.

This said, we can't make life estimate on a device which is beyond our capabilities. However nothing that we have done in our history has lasted long with no maintenance.

Roman aqueducts have been in use for a couple millennia, but with some maintenance, and they are one of the longest working structures I can recall (excluding tombs which are mot exactly "working" things).

You can make your story without having to show the FMEA of your design. Suspension of disbelief works well as long as you don't overdo.


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