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Any ideas on experiments to determine what causes a planet's magnetic fields? I thought I'd read on here that even though conventional wisdom says its related to a planet having a large molten core this idea is less well supported than most things accepted as scientific fact. This seemed like the best forum to put this in as it seemed like something a robotic probe could do better than a manned mission. As best as I can remember Earth and Jupiter are the only planets with significant magnetic fields. I ask because this seems to me to be an important thing for human habitation of other worlds if only because it is something naysayers bring up so often. Before we can do anything with some chance of it working we need to know what to do which leads us back to the above question of determining the cause of planetary magnetic fields.
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Not sure about venus, but mars, pluto, and most every other rocky body in the solar system are all pretty inert in terms of magnetic activity.
Mostly it's convection currents driven through the core by radioactive decay. Starts out hot, and stays hot due to its mass and the excess heat of decay.
Beyond that, once a current is set up, it's sort of self-sustaining.
There was some research a while back using about a ton of molten sodium in an insulated spherical vessel. They tried to mimic conditions in the core of the earth, and got some promising results that roughly agreed with theory.
it would seem that once a magnetic feild is set up in the core, the current path is restricted by the same feild that it created, so instead of random bubbles of hot gunk moving around, it's a pretty steady-state flow. Feild disturbances occur, however, and that is what leads to current instabiltiy and new feild evolution/polar shift.
This is all just info that i've collected over the years, so there may be some innacuracies and some incomplete information, but this should give you a good start to look for things on document services (NASA/JPL for one...) and google.
Hope it helps,
Rion
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