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I was reading a 2017 article on a potential that Mars could be terraformed using a magneto-tail; A Future Mars Environment for Science and Exploration. This would basically entail sticking a giant magnet that carried a charge between 10,000 and 20,000 Gauss at the Mars' L1 point.

Models hosted at the Coordinated Community Modeling Center (CCMC) are used to simulate a magnetic shield, and an artificial magnetosphere, for Mars by generating a magnetic dipole field at the Mars L1 Lagrange point within an average solar wind environment. The magnetic field will be increased until the resulting magnetotail of the artificial magnetosphere encompasses the entire planet as shown in Figure 1. The magnetic field direction could also maintain an orientation that keeps it parallel with the impinging solar wind interplanetary field thereby significantly reducing mass, momentum, and energy flow into the magnetosphere and thus also damping internal magnetospheric dynamics. This situation then eliminates many of the solar wind erosion processes that occur with the planet’s ionosphere and upper atmosphere allowing the Martian atmosphere to grow in pressure and temperature over time.

Figure 1: https://i.stack.imgur.com/UQJNW.jpg

Three questions I have about this article:

  • How big would the magnet have to actually be to have a significant effect on Mars?
  • What material could be used to construct something so large w/ such a high magnetic charge?
  • Would a magnet this large, with this high of a charge, even be transportable using conventional rocketry? Or would it drastically interfere with the functioning of a modern rocket? Organic Marble pointed out it would likely be an electromagnet with a negligible charge when inactive.
uhoh
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Magic Octopus Urn
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    Not commenting on its feasibility, but it would probably be an electromagnet, so you wouldn't turn it on until it was in place. (addressing the 3rd bullet) – Organic Marble Aug 17 '18 at 13:32
  • An electromagnet would be adjustable, which might be useful. Store charge in a battery when you need extra protection, perhaps? – Don Branson Aug 17 '18 at 14:09
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    An electromagnet to create an artificial magnetosphere for Mars should have the size of the planet. The electric currents in the Earth causing the natural magnetosphere flow below the surface within the hot core. The "coil" is somewhat smaller than the diameter of Earth. – Uwe Aug 17 '18 at 16:00
  • There still is a lot of room for exploration on the science of this. I've seen experiments that have successfully recreated the structure (not scale) of the Earth's magnetosphere by spinning molten sodium in a giant sphere. For all we know there could be an artificial form and material construction that can generate a superior magnetic field than that created by natural planetary constructs. New discoveries are taking place every year for findings in chemistry on reactions occuring outside STP. The moon's of Jupiter alone have been demonstrating interesting magnetic phenomena. – anon Aug 17 '18 at 18:27
  • @anon neat-- which moons and do you have links to the studies on the magnetic phenomena you're talking about? – Magic Octopus Urn Aug 18 '18 at 04:02
  • However superior the magnetic field may be, where comes the enormous amount of energy from to create it ? Would it not be more practical to start at a local level, like a magnetic field just above Gale crater ? – Cornelis Aug 18 '18 at 08:37
  • A small local magnetic field should be very strong to deflect the charged particles to acheive a protective effect. – Uwe Aug 18 '18 at 15:46
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    Not really a duplicate but THIS is very closely related to your question although with a different approach. – CKA Aug 20 '18 at 08:09
  • “A giant magnet that carried a charge between 10,000 and 20,000 Gauss” isn't a useful statement: the magnetic flux density, which is what you measure in Gauss or better in Tesla, can easily be made very strong in a small space. 2 T is perfectly doable in the laboratory, even with simple permanent magnets or copper coils. In fact, for any idealised dipole, the flux density goes to infinity at small distance. Flux density does not tell you how strong a magnet is. The actually interesting quantity is the dipole moment. – leftaroundabout Aug 20 '18 at 14:45
  • @Conelisinspace a local magnet field wouldn't prevent the solar wind from depleting the atmosphere. About the energy – that might actually not be the biggest problem. You'd use a superconducting magnet for this, and those can be slowly energised, building up an ever-stronger circular current that will then keep flowing even when the power supply is cut. The needed energy would no doubt be big, but it could be gathered over a long time with large solar arrays. The bigger problem would be getting the enormous superconducting coils plus cooling equipment to Mars-L1. – leftaroundabout Aug 20 '18 at 14:50
  • Alternate artificial magnetosphere: Run an electric cable N times around the surface of Mars, with current A. Can anyone calculate the shape and strength of resulting magnetic field? – MBM Apr 06 '19 at 00:38

2 Answers2

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Hmmm this is an interesting theory, though I am confused how they would maintain that position between Mars and the Sun. Moreover I want to point out this is theoretical and is not actually building or making a magnetosphere around Mars. It's more like making a shield between the Sun and Mars. This sort of raises the question of whether the value of a magnetosphere is really just in deflecting solar winds or if it plays other roles in retaining atmosphere.

Anyways, to answer the question:

10-20K Guass isnt that much:

3000–70,000 gauss – a medical magnetic resonance imaging machine

So for the question of size we have hospital MRI machines currently the size of a few refrigerators that can generate that field or greater.

As for material composition: - lots of copper wire - maybe some iron or other metal - maybe some rare earth magnets like neodymium - maybe superconductors

At 10-20K Gauss and the size of current satellite capabilities, the material compositions are relatively insignificant factors. I think the logistics of maintaining the solution both in power and orbit are far more troublesome.

But it's an interesting theory.

anon
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    As far as I understand 20k Gauss is the intensity of the magnetic field, not how big it is. I don't think a magnetic resonance machine on L1 would produce a magnetic field big enough to shield Mars. More likely, the field will have to be thousands square kilometers big... Can we build such a huge magnetic resonance machine? Now that's something entirely different... https://en.wikipedia.org/wiki/Gauss_(unit) – BlueCoder Aug 20 '18 at 19:31
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Anon answered with Rare Earth Magnets---visa vis neodymium. Don't forget that the (apparent) abundance of Rare Earth Elements---visa vis KREEP, will inevitably (if extended from the Apollo landing sites) generate a super-conductive metals/coils/wires capability that will make the production of various electro-magnets natural to lunar mining economy.

ThunderWarEagle
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