A couple weeks back we checked DuPont and Murphy, on the assumption of Earth being 1.88 times Mars' radius. Suppose Mars' radius was wider at the equator by, oh, 110 km. Their equation was B' = B🜨 × [Earth distance in Mars' units] × [Earth radius in Mars' radius]3 × (r's / rs)3. Math.Pow(6371.0/3500, 3.0) / 1.38 = 4.37.
Mars is now looking at a magnetic field 1/50 B🜨, just by raising that coil into a (very) low orbit. That is less than their estimate 1/40 and even mine own 1/45. That's one microtesla by their estimates, not 1.25; although I'd keep a bit over 1 μT just to allow for Earth's high-end, in case of cosmic rays.
Further advantage: since this chain is in orbit, Mars doesn't have to run it over Mount Olympus and across the Marinaris. They do have to supply it with energy but DuPont and Murphy thought they could do this with one megawatt. On the surface they cited wind-turbines as good-enough; in orbit, once it's magnetised, hanging ten square meters of 20%-efficient solar-panel to face the sun should catch the 586.2 W/m2 to keep it magnetised.
So: Mars shall has 225,000 cubic meters of good ol' Bisco ringing it 'round. Working from 3000 kg/m3 DuPont and Murphy came up with 675,000,000 kg = 6[.75] × 1011 g. Bisco's actual density is 6310 kg/m3, and its competitors in the Rebco range aren't much less, so I'm going with 1420 kilotonnes. I never was much fond of this duo's math. But anyway:
We are already planning on a Ring Of Iron, starting at 90 kilotonnes. This can already hang those 10 square meters of solar-panel to keep cool; it's not 1982 anymore, superconductors are feasible. It will be paying for itself in launch savings before any terraforming is even started. Adding to this ring will only add to its magnetic force, so the mass of exports the ring can pull at one time. We just have to command it to be equatorial - but that's not a problem, since we were slating our first such ring to feed Deimos anyway.
The structural-engineers down planetside can concentrate on building the Martian cities and railways. And boosting rare-earths and/or bismuth should Phobos run out.
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