I was doing research on the terraforming of planets with a solid iron core and no magnetic field and saw a few suggested ideas for starting a magnetic field on Mars that got me thinking.
Most of what I read suggested that if you could get a planet to rotate faster, the core temperature would increase and return its core to a molten state, restarting convection and generating a magnetic field. I'm going to use Mars for this example, but I'm looking to apply this to other planets as well.
The common solutions I saw were the following:
Hit it with asteroids at the right points to give it some spin (could potentially destabilize orbits of Mars and other planets.)
Slingshot asteroids or planetoids around Mars.
Move a planetoid with a quarter of Mars's mass into its orbit to use tidal forces to generate the kinetic energy needed.
I'm planning to go with the third approach in this setting, but had an idea.
Would a belt of asteroids with a total mass equal to one quarter of Mars's mass yield similar results on its rotation speed to a singular planetoid?
The thought is, instead of locating and moving an adequate dwarf planet into Mars's orbit and all of the energy required for that, redirect smaller asteroids from our asteroid belt into Mars's orbit over time so there isn't one astronomical upfront cost and money could be saved by reusing equipment on the next few asteroids. I'm imagining a group of automated reusable asteroid tugboats/pushers.
Or would that amount of energy and effort be better spent applied directly to the planet itself?