Though if it is released into the atmosphere, won’t it all just get blown away without a magnetosphere?
https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmo...
The article is unclear whether this is 1 or 2 Tesla at a point, or if what's needed is a field that's 1 or 2 Tesla over a large area, which would be a lot more than "an MRI machine's worth". Interesting idea anyways.
Also suspiciously absent is any mention of how long this kind of change would be expected to take... I would be legitimately surprised if it'd take less than 20 years though, which is somewhat implied by the paragraphs that follow:
>"A greatly enhanced Martian atmosphere, in both pressure and temperature, that would be enough to allow significant surface liquid water would also have a number of benefits for science and human exploration in the 2040s and beyond," ...
A lot of it does seem to be very carefully avoiding making any clear statements or connections between critical bits of info though. There's room for "that wasn't claimed" arguments, but it's certainly standing very close to some lines...
I don't have the technical expertise to estimate if such a project would require mere billions, or planetary sized piles of money.
I'll point out you couldn't just park it at L1. If it's deflecting the solar wind, then it's acting as a solar sail. You would need active propulsion to keep it on station.
https://solarsystem.nasa.gov/resources/754/what-is-a-lagrang....
Assuming the solar wind is constant, you could presumably park it somewhere other than L1. That's certainly not a valid assumption, though, so propulsion is going to be necessary.
Superconductors stop superconducting at very high B field strengths, which limits them to carrying less than an infinite current.
The main issue after simply having oxygen is that the martian atmosphere has so much CO2 and so little everything else. Considering that subsurface temperatures can get low enough to sublimate CO2 into dry ice, you could potentially (and I say potentially because this isn't my specialty by any means) build an air production loop that uses relatively little power other than to drive the plasma reactor itself and a thermal pump to bring cold fluid to the surface to chill the oxygenated air so that the CO2 sublimates out. Of course here you could also just use energy to chill the gas via a compression chiller or make some tradeoff between the two. This process would move you along the following steps:
Standard Atmosphere with 95% CO2, 2.5% N2, and 2.5% trace elements (mostly argon, also a very small amount of O2, and a tiny amount of CO).
After Plasma Reactor: 65% CO2, 30% O2, 2.5% N2, and 2.5% trace elements.
After Sublimation: Lower volume of gas with 85% O2, ~7% N2, 5.5% argon (from trace elements), and the rest of the trace elements. And the CO2 is now dry ice.
Then it's just a matter of diluting the "purified air" with nitrogen or other inert gasses, adjusting the pressure, and preventing buildup of any nasties in the trace elements (such as the carbon monoxide). Now you should have breathable, earth-like atmosphere for suits and cabins.
This is mainly based on my knowledge of processes we use on earth already for extracting stuff from the air so caveat that I could be missing important details.
Of course “Corey” (The Expanse) are probably right that each colony will develop her own personality, and it will be difficult to abandon any of them. The cultural trauma of such an event could be profound.