3 ms·

Can we give Mars a magnetic field? Crash a million iron-rich asteriods on it, and magnetize them? Or do you really need a hot iron core?

bayesian_horse 7y ago
I'm really no expert. I guess the iron core of the earth is too big to be feasibly replaced by asteroids "crashing" on mars. I'd further guess that it would be easier to do the same with some sort of electromagnetic field. To enclose the whole planet would also be a giganteous undertaking. Much easier would be local field generators on the surface, maybe powered by a fusion generator. At best this would be centuries in the future, at worst this doesn't make sense at all because it would require less energy/resources to construct huge greenhouses/domes that achieve the same thing and more. The more immediate obstacles to colonizing Mars seem to be getting there in the first place, getting enough stuff there on a permanent/continuing basis for a few dozen people to live there for a few years, including radiation shielding. It would be a really long time until there is a financially self-sustaining "colony", let alone one that can produce all of its own foods and much of its own technology and other resources. I figure it will be centuries until people even think about anything terraforming-related seriously.
wongarsu 7y ago
The most viable proposal so far is to place a strong electro magnet on the Lagrange point between Mars and the sun. If sized correctly this acts as a radiation shield similar to a planet's magnetic field, with the restriction that it only works for radiation from the direction of the sun (which is the overwhelming majority). Such a project would be achievable in the near future. I think we don't quite have sufficiently strong magnets yet, and it wouldn't be cheap.
pfdietz 7y ago
One could run superconducting cables around the planet. The mass required is prodigious, but the energy requirements would be surprisingly small. The magnetic field of Earth above the surface stores about 100 megatons of magnetic energy; on Mars, and if the field were a bit weak, the energy needed would be much less.
- prewett 7y ago
  Were you thinking 100 MJ perhaps (which seems awfully low). Energy isn't normally measured in tons. But if you were applying e = mc^2, then that would be 8.988e21 MJ [1], which is a considerable amount of energy. [1] https://www.omnicalculator.com/physics/emc2 https://www.omnicalculator.com/physics/emc2
  - pfdietz 7y ago
    The energy stored in the part of the Earth's magnetic field above the surface is about the same as the yield of a 100 megaton nuclear bomb. This is about 4e17 J, or about 13 gigawatt-years. Mars is smaller, and so the volume of the magnetic field would be smaller, and a lower field is probably enough. Since stored energy goes as B^2, maybe this energy could be reduced by two orders of magnitude.

bayesian_horse 7y ago

I'm really no expert. I guess the iron core of the earth is too big to be feasibly replaced by asteroids "crashing" on mars. I'd further guess that it would be easier to do the same with some sort of electromagnetic field. To enclose the whole planet would also be a giganteous undertaking. Much easier would be local field generators on the surface, maybe powered by a fusion generator. At best this would be centuries in the future, at worst this doesn't make sense at all because it would require less energy/resources to construct huge greenhouses/domes that achieve the same thing and more. The more immediate obstacles to colonizing Mars seem to be getting there in the first place, getting enough stuff there on a permanent/continuing basis for a few dozen people to live there for a few years, including radiation shielding. It would be a really long time until there is a financially self-sustaining "colony", let alone one that can produce all of its own foods and much of its own technology and other resources. I figure it will be centuries until people even think about anything terraforming-related seriously.

wongarsu 7y ago

The most viable proposal so far is to place a strong electro magnet on the Lagrange point between Mars and the sun. If sized correctly this acts as a radiation shield similar to a planet's magnetic field, with the restriction that it only works for radiation from the direction of the sun (which is the overwhelming majority). Such a project would be achievable in the near future. I think we don't quite have sufficiently strong magnets yet, and it wouldn't be cheap.

pfdietz 7y ago

One could run superconducting cables around the planet. The mass required is prodigious, but the energy requirements would be surprisingly small. The magnetic field of Earth above the surface stores about 100 megatons of magnetic energy; on Mars, and if the field were a bit weak, the energy needed would be much less.

prewett 7y ago
Were you thinking 100 MJ perhaps (which seems awfully low). Energy isn't normally measured in tons. But if you were applying e = mc^2, then that would be 8.988e21 MJ [1], which is a considerable amount of energy. [1] https://www.omnicalculator.com/physics/emc2 https://www.omnicalculator.com/physics/emc2
- pfdietz 7y ago
  The energy stored in the part of the Earth's magnetic field above the surface is about the same as the yield of a 100 megaton nuclear bomb. This is about 4e17 J, or about 13 gigawatt-years. Mars is smaller, and so the volume of the magnetic field would be smaller, and a lower field is probably enough. Since stored energy goes as B^2, maybe this energy could be reduced by two orders of magnitude.