One of the many conditions needed to support life (as we know it) is a planet with a surface protected from deadly radiation from a sun or even other sources. In the grand scheme of things, the probability of finding a planet that meets every requirement may be rather slim. That is to say, there is a long list of requirements including things like: is there a moon, distance to sun, metallicity of sun, surface gravity of planet, atmospheric composition, size of planet's core, ect. If the universe is infinite then by the law of large numbers we may be bound to find one eventually. That being said, there is no guarantee that the law of large numbers is going to let you find a suitable planet that is close enough for a reasonable journey duration.
Hypothetically, consider a relatively close planet that met all requirements except for the core of the planet was not large enough or not made of heavy enough elements to generate a magnetosphere capable of shielding the planet from radiation. Then suppose a fairly advanced civilization discovers this planet. They may say to themselves, "this planet is so close", and proceed to make do. If their technology was advanced enough, I suppose they could create their own external magnetosphere. However, I am left wondering, in the absence of overly advanced technology, what is the feasibility for strengthening a planets magnetosphere?
Question: That is in essence the question. Can a planet's magnetosphere be strengthened through artificial means?
- the lower tech, the better
- could be a planet-core oriented solution
- could be some surface device magneto-amplification solution
- thresholds in answer would be a plus (what size or ratio is workable, what is beyond salvaging, ect)