RE: modern use of moon dust by YECs
Vandergraaf, Chuck (vandergraaft@aecl.ca)
Wed, 4 Nov 1998 09:41:52 -0500
Art,
> >2 - Lunar soil. The dirt on the moon's surface does not show the amount
> of
> >soil mixing it should have, if the moon were very
> >old.-p. 17. 3 - Lunar isotopes. Short-term radioactive isotopes (uranium
> >236 and thorium 230) have been found in the collected
> >moon rocks. These isotopes do not last long and rather quickly turn into
> >lead. If the moon were even 50,000 years old, these short-life
> >radioisotopes would long since have decayed into lead. The moon cannot be
> >older than several thousand years.-p. 17.
>
> So the moon is young, but the earth, which lacks such isotopes is old?
> How
> does this help their cause?
>
The earth does NOT lack these isotopes. Th-230 is formed as follows:
U-238 emits an alpha particle to form
Th-234 emits a beta particle to form
Pa-234 emits a beta particle to form
U-234 emits an alpha particle to form
Th-230 emits an alpha particle to form
Ra-226 emits an alpha particle to form
Rn-222, etc. until we get to lead.
The source term for the Th-230 is U-238, which has a half life of 4.51 x
10^9 years. As long as there is U-238, there will be Th-230 formed.
U-236 is a bit of a puzzle. Its precursor could be Pu-240 which decays by
emitting alpha particles. It is possible that neutron bombardment from
cosmic rays generates Pu-240 from U-238 by two successive (neutron,gamma)
reactions to form U-240 which would then decay by beta emission via Np-240
to Pu-240.
To state that the relatively short lived Th-230 and U-236 should have
decayed to lead is misleading because both isotopes would continue to be
formed.
Hope this helps.
Chuck Vandergraaf
Pinawa, MB