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Comment by thatoneguy | Hacker News Reader

NASA thinks we can just park an MRI machine's worth of magnetic shield a million miles in front of Mars to fix the issue.

https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmo...

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> "In the future it is quite possible that an inflatable structure(s) can generate a magnetic dipole field at a level of perhaps 1 or 2 Tesla (or 10,000 to 20,000 Gauss) as an active shield against the solar wind."

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.

>As a result, Mars atmosphere would naturally thicken over time, which lead to many new possibilities for human exploration and colonization. According to Green and his colleagues, these would include an average increase of about 4 °C (~7 °F), which would be enough to melt the carbon dioxide ice in the northern polar ice cap. This would trigger a greenhouse effect, warming the atmosphere further and causing the water ice in the polar caps to melt.

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...

We are clearly talking about a planetary-sized magnetic field. But I don't think it's in the realm of impossibility. With a sun-shade like that of JWST, temperatures naturally drop to superconducting ranges and at that point a closed electric loop has effectively zero resistance. So, at least in theory, you could induce an infinite current into it, slowly gathering solar energy until you build up the required magnetic field. The limiting factor would be the physical strength of the winding.

I don't have the technical expertise to estimate if such a project would require mere billions, or planetary sized piles of money.

I don't think the carrying capacity of superconductors is infinite. If you exceed the capacity, the superconductor "quenches" and ceases to be superconducting.

Interesting. That's actually very achievable.

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.

I was thinking the same thing but you likely have an area to work with however L1 points are unstable as it is and require satellites to alter the courses every once in a while potentially if you use the magnetic field as a light sail slightly in front of the point you'd be balanced between the sun and mars with less active thrust

https://solarsystem.nasa.gov/resources/754/what-is-a-lagrang....

> 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.

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.

> So, at least in theory, you could induce an infinite current into it,

Superconductors stop superconducting at very high B field strengths, which limits them to carrying less than an infinite current.

Sounds like an incredible single point of failure. You would have to keep it constantly maintained and fuelled, and maybe build ten of them for redundancy, and even then whoever controls them would be able to hold the entire planet to ransom.

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