🚀 go-pugleaf

	I just used or libraries computers to see if there was some
recent stuff on lunar orbital changes due to tides.  I found a couple
of articles that seemed like they're worth checking out:

Cheng, MK, Eanes, RJ, & Tapley, BD, Tidal Deceleration of the Moons Mean
Motion, Geophysical Journal International, v.108, p.401-409

Dehant, V, Review or the Earth Tidal Models & Contribution of Earth Tides
in Geodynamics, JGR-Solid Earth, v.96, p.235-240.

Williams, GE, Tidal Rhythmites - Key to the History of the Earths
Rotation and the Lunar Orbit, Journal of Physics of the Earth, v.38, p.475-491

This last one discusses paleo-evidence of the lunar period, probably more
what you wanted... sounds like the lunar recession may have speeded up a
bit around now, maybe a factor of 2 slower 600Ma ago.  I've heard of this
before, and I dimly recall speculation that it was a resonance in the
ocean tides with their basin sizes.

I'm sure you're aware that they're now directly measuring the lunar
recession speed with laser ranging.  This is what is compared with the
paleo-evidence.

If you know the distance to the moon, you can calculate the rotation rate of
the Earth, assuming that the angular momentum of the Earth-moon system hasn't
changed over the time-scale you're considering.

I don't think I'd ascribe much depth to the similarity of Press & Siever's
11hr day being like the rotation rates of Juptier or Saturn.  I think that
most people feel that the moon was somehow created in some sort of a 
cataclysmic event with the earth, which would have significantly altered
the angular momentum of the system from what it may have been primordially.
On the other hand, there is a theory regarding the rotation rates of
primordial bodies, but I'm not knowledgeable enough to even hazard a
description of it here.  Jack Lissauer and (separately, I believe) Luke
Dones & Scott Tremaine have worked on it.  Look for some recent papers of
theirs.

As far as how tidal recession is a function of distance from the central body,
I'd look at a few papers by Peter Goldreich. Namely the bunch from around
1965.  He derives the tidal changes there.  He also wrote a paper, around
1967 that discussed the tidal history (and future?) of the moon.  Try
Q Values in the Solar System, Icarus v.5, p.375-389...

I hope these ramblings help....			Don Banfield
						Caltech Planetary Science
						djb@cluster.gps.caltech.edu