Shouldn't this theory be able to be applied to other
planets?
Yes -- certainly ! ....also to sub-stellar
objects called brown dwarfs -- see current issue of Sky &
Telescope.
If the elements in the pre-planetary accretion
disc were stratified by gravity,
wouldn't Venus and Mercury have a high
chance of having a higher
concentration of fissionable isotopes in their
core?
From what I've read about this issue, the stratification was more on the individual planetary level than in the accretion disc -- the difference being that the planets closer to the sun had their share of the light chemicals (hydrogen, methane, ammonia) largely evaporated away, leaving just the rocky residue.... also, the lower the initial mass of the planet or moon following formation, the weaker its gravitational field and the faster the rate of loss of the light elements to space, leaving behind the heavier chemicals like nitrogen and water (earth), carbon dioxide (Mars), or nothing at all (earth's moon, Mercury).
If the nuclear core is a product of your position in
the solar system how does Jupiter manage
to generate so much
heat?
Jupiter & the other giant gas planets all have a rocky core, comparable to the size of the earth, but buried under thousands of miles of hydrogen, methane, ammonia, nitrogen, etc., in gaseous, liquid and solid (metallic) form.
Also, how does a five mile ball of uranium fit into the model of earth's estimated mass?
Pretty
insignificant
Also, what does this do for those long lived
"naturally abundant" isotopes on our planet which are not part of the natural
decay series? Are they early fission products or cosmogenic?
Not cosmogenic and not early fission products, but products of stellar nucleosynthesis -- specifically fusion processes in late stellar evolution stages of very massive, short-lived stars, and in supernova explosions.
To bad we don't have any planetary geologists on the list. I knew
one but
lost track of him a few years ago.
More semi-ignorant
ramblings from yours truly.
Kim Merritt, RRPT
Radiation/Laser
Safety Officer
NASA Langley Research Center
Hampton,
VA
(757)864-3210
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