[meteorite-list] new formation mechanism

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 19 Apr 2007 23:17:33 -0500
Message-ID: <05dd01c78302$d2c9c400$862e4842_at_ATARIENGINE>

Hi, Ed, List,

    The only "new" part is the notion that these early
planet-sized bodies get all their crusty mantles knocked
off their cores right away. Think of it as the "Naked
Core Theory"!

    General consensus, dating all the way back to
Wetherill and demonstrated by more recent computer
simulations, is that the inner solar system requires
the following minimum set of ingredients:
    1000 1000-kilometer planetesimals
    100 3000-kilometer planetesimals (Moon-sized)
    10 5000-kilometer planetesimals (Mercury-sized)
    2-3 8000-kilometer planetesimals (Mars-sized)
    Directions: STIR WELL!

    The truth is, if you start your computer simulation with
only 1000 1000-kilometer planetesimals, you may not get
a solar system at all -- too puny. It's usual to start with about
10,000 1000-kilometer planetesimals!

    Picture all 1000 or 5000 or more, all bigger than the Dwarf
Planet 1 Ceres, careening around the inner solar system, bonk,
bonk, bonk! like a pinball game! Would you be surprised if
a lot of them lost all or most of their crust and mantle to
impacts?

    In fact, if we going to take this Naked Core Planetesimal
Theory seriously, why do we need ANY special case, like
a Big Whack, to explain why Mercury has such a big core
and such a small mantle? Couldn't it have accreted directly
from these planetesimals that are mostly core?

    It's always better when some puzzle is explained as a
direct result of the prevailing conditions and doesn't need
a special mechanism to account for it!


Sterling K. Webb
-----------------------------------------------------------------------
----- Original Message -----
From: "E.P. Grondine" <epgrondine at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Thursday, April 19, 2007 9:45 PM
Subject: [meteorite-list] new formation mechanism


Hi -

And just to think, only a few years ago I constantly
got reminded about McSween's Meteorites and Their
Parent Bodies whenever I brought the topic of a larger
parent body up.

Now we have the LPBE, that was 3.8 or 4.2 Gya, or
both?

<http://www.hawaii.edu/cgi-bin/uhnews?20070418141659>


good hunting all,
Ed
Received on Fri 20 Apr 2007 12:17:33 AM PDT