[meteorite-list] Pairing S-Type Asteroids to OC's (from Arkansas)

From: mexicodoug at aim.com <mexicodoug_at_meteoritecentral.com>
Date: Thu, 10 Jul 2008 16:22:02 -0400
Message-ID: <8CAB0E1BF70D254-1BF0-2906_at_webmail-db04.sysops.aol.com>

http://www.sciencedaily.com/releases/2008/07/080710103903.htm

The press release was confusing to me at first, highlighting the
Fayetteville H4 (fall, Arkansas) meteorite. Perhaps they did because
of being fresh and closer to the surface (?) in the parent body model.
Not sure why the 1270 Datura family, etc., would be expected to be from
the relatively rarer surface of the original parent body vs more common
heat altered interior).

In any caseit seems they are NOT claiming that (1270) Datura is the
parent body to any of our meteorites (how could it be - don't virtually
all ordinary chondrites have CRE's of floating around as meteoroids
well over 1 million years?)

However, it seems they are pointint out that because it is an S-type
asteroid that has apparently suffered a collision only 450,000 years
ago(which was shown by other researcher a studying the probabilities of
members' orbits couple of years ago), it gives an opportunity to study
fresher material of this most common high silicate asteroid type by
telescopic spectroscopy, and they had an opportunity to take the
spectra. I guess they only look at the 0.5 and 1 um peak because it is
more sensitive to space weathering (?), but this isn't too clear
either. (the authors didn't extend it to the typical 2.5 microns where
some good stuff is visible - at least not in figure in the press
release).

In any case, their proposed contribution seems that they measured
spectra of theyoung Datura family and compared it to ordinary chondrite
spectra and got a better match than ever before helping to solve the
conjecture that the common asteroid class (second only to supposed
carbonaceous chondrites typed asteroids) should be paired to common
meteorites. Hopefully they make a case for a trend in asteroid
reflectance spectra vs. age, vs. a one hit wonder, but there still seem
to be more complexities to be ironed out regarding what meteorite is
appropriate to compare to what asteroid in the clan, IMO. Maybe
Fayetteville was just selected because it is what they had access to...
 Article sounds like it will be a good one. Comments?

Best wishes, Doug

PS Interestingly, Wikipedia (at this moment - no doubt it will be fixed
by someone reading this) says the Datura cluster formed 450 MILLION
years ago and a probable source of zodiacal dust.... Maybe Wikipedia
can't be trusted yet again, once the dust has settled :)
Received on Thu 10 Jul 2008 04:22:02 PM PDT