Asteroid geology, was Re: [OT]Nukes... tunnels.... boom....

Hi,

There are very few inherently radioactive elements. Typically, one talks about
radioactive isotopes. An element is defined by the number of protons in the
nucleus. The difference between isotopes is the number of neutrons. Whether or
not a particular isotope is radioactive is not entirely dependent on the mass
of the isotope. Some very light isotopes are highly radioactive. Tritium comes
to mind.

Typically, the formation of elements happens in a set way, and the ratio of
stable to radioactive isotopes is mostly fixed at the time they are created.
Geologists use this to estimate the age of rocks. They find a rock, and
measure the ratios of stable and radioactive isotopes. Knowing the half life
of each isotope allows them to calculate how old the Earth (or other body) was
at the time that the elements in the rock were amalgamated.

What this means is that, wherever a particular element is found, there will be
both radioactive and stable isotopes found in ratios that depend mostly on the
age of the body.

Within our solar system, the composition of the planetoids seems to be
directly related to their distance from the sun, or at least on the distance
they were when they were created. One thing that we know very well is that the
Moon is the geological twin of the Earth.

Therefore, I would conclude that most, if not all, bodies in the solar system
contain radioisotopes.

TTYL,