From: roberts@cmr.ncsl.nist.gov (John Roberts)
Newsgroups: sci.space
Subject: Re: More on the lunar questions
Date: 8 Nov 92 05:16:05 GMT
Article-I.D.: cs.BxDtC9.84r.1
Distribution: sci
Organization: National Institute of Standards and Technology formerly National Bureau of Standards
X-Added: Forwarded by Space Digest
Original-Sender: isu@VACATION.VENARI.CS.CMU.EDU


-From: jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins)
-Subject: Re: NASA Coverup
-Keywords: Ten Embarrassing Questions about the Moon
-Date: 7 Nov 92 23:42:20 GMT
-Organization: University of Illinois at Urbana

A few quotes from the text I mentioned before (Lunar Science: A Post-Apollo
View) relevant to two of the items you list:

-snarfy@cruzio.santa-cruz.ca.us writes:

->  6 . Is the core of the moon hot or cold ?

-"Scarfy" makes some strange comments here and a few logic leaps that lost me.
-The core of the Moon is solid.  This explains its weak and disorganized magnetic
-field and the lack of siesmic activity.  This also makes sense given the small
-size of the Moon - it would have cooled faster than earth.

[Structure of the lunar interior]
"1000-1738 km (The 'Asthenosphere')

"The announcement in November, 1972, that a portion of the interior of the moon
was partially molten ranks high among the many exciting discoveries about the
moon. The evidence came from the impact of a large meteorite (weighing about
1 ton) on the far side of the moon in July, 1972. P waves were transmitted,
with slightly lower velocities through the moon, but S (shear) waves, which are
not transmitted through liquids, were missing, indicating a central zone of
600-800 km radius at a depth of about 1000 km. Either the shear waves did not
propagate at all or were so highly attenuated as not to be recorded.

"The transition to the melting zone is gradual, not sharp. The P-wave
velocities decrease by 0.3 km/s, a slight drop compared with the mantle core
interface in the earth, where the P-wave velocity drops by about 5 km/s.
Thus this zone in the moon is neither completely molten nor a phase change.
The analogy is much closer to that of the "low velocity zone" in the earth's
upper mantle than with the core. This has led to the rather general use of
the term 'lunar asthenosphere'. The limits for an iron core, as noted earlier,
set by the density and moment of inertia are about 400km radius, much deeper
than the partial melting zone discussed here. An Fe-FeS core radius of 700 km
is permitted by the data." (pp. 291-292)

[Note that this is a 1972 finding, published in a book in 1975. It may not
be fully up to date on such a recent item. Also, this *doesn't* say that
the zone of partial melting necessarily extends all the way to the center.]

->  9. What are "mascons" and how did they get there?

-The mascons (mass concentrations) are
-the remains of large meteorites buried under the lunar maria.  

"It is now clear that the mascons are near-surface features rather than
deep seated. They are most closely simulated by surface disk-shaped bodies
rather than deep-buried spherical bodies and show a good correlation between
surface area of the mare basalt fill and the size of the mascon." (p.279)

[In other words, it seems to be the lava rather than the material of the 
impacting body that's the main contributor to the mascon.]

John Roberts
roberts@cmr.ncsl.nist.gov
Newsgroups: sci.space