[X] My Assistant

[Juramike]

Recent space.com article describes H2O detected in Apollo samples of volcanic glass beads:
http://www.space.com/scienceastronomy/080709-moon-water.html

The authors estimate this implies a concentration of 260 ppm H2O in the lunar magma. [The article states this is close to the level of H2O in some Earth magma environments]

-Mike

[dvandorn]

I'm unsure of that radon report -- the Moon doesn't follow the same rules as worlds that accreted more slowly and melted from the inside out.

The Moon melted more from the outside in. Some decent information developed from study of lunar volcanic glasses, and the gasses and traces of volatiles found on and in the glasses, strongly indicates that the Moon's core is an unmelted, undifferentiated mass of chondritic material. There seems to be a still-molten lower mantle in which the core moves *separately* from the outer mantle and crust; The Moon's core actually seems to move and librate within at different rates, and with different motions, that the outer mantle and crust, even today.

But in a system where the entire body didn't melt, very heavy elements like uranium would sink to the bottom of the lower mantle and then stop. That inevitably means that uranium and other heavy radioactive elements would be located non-uniformly. I can imagine quite well enough local melting from radioactive "hot spots" to keep the lower mantle liquid and create just enough sluggish movement in the mantle to allow the progression of gasses up through to the surface. But in widely scattered spots.

See -- the Moon, to me, is still a puzzling place where the rules seem to have been turned upside-down, a place that still offers an awful lot for us to learn about how planetary bodies form. There have been many tantalizing hints of processes we'd never, ever have suspected. The old "been there, done that" attitude about studying the Moon is just not a rational attitude, to me... *sigh*...

-the other Doug