[meteorite-list] Meteorite Questions

From: star-bits at tx.rr.com <star-bits_at_meteoritecentral.com>
Date: Wed, 29 Aug 2007 17:31:52 -0700
Message-ID: <22762274.1188433912416.JavaMail.root_at_web29>

Walter branch wrote:

<Traveling over eons to make it to the inner solar system, how can a
meteoroid stream stay intact enough to cause a tiny strewnfield on the
Earth? I would not think that the Earth's gravitational field would be
strong enough to do what Jupiter did.>

     The small strewnfields are caused not by meteoroid streams, but by an asteroid which is gravitationally clumped rocks and not a solid chunk. Because they are just gravitationally attached to each other the earths gravity probably starts separating them and then the atmosphere easily separates them farther.
 
     <Also, I know I have asked this before but I still don't understand how
researchers can determine cosmic ray exposure ages for a meteorite which
ablated a significant portion of the material that absorbed most of the
cosmic rays and which may have fragmented in flight through the Earth's
atmosphere. >

     One way of doing this is using Neon isotopes. I forget the exact details, but the relative abundances of the neon isotopes can be used to determine depths. This can then be used to make a correction for depth for the other noble gases which are then used for calculating the CRE.

--
Eric Olson
7682 Firethorn Dr
Fayetteville, NC 28311
http://www.star-bits.com

Received on Wed 29 Aug 2007 08:31:52 PM PDT