Hi List...I want to clarify that Elton did not specifically write me that
"ALL of the largest asteroids have already been located" and I want to go on
record to acknowledge this and apologize if I took his words out of context.
It is an honor to read from you all!
Richard Montgomery
----- Original Message -----
From: "Richard A. Kowalski" <[email protected]>
To: "Meteorite List" <[email protected]>
Sent: Wednesday, April 13, 2011 10:00 PM
Subject: Re: [meteorite-list] Cold Asteroids May Have A Soft
Heart(AllendeMeteorite)
[My original post from my yahoo address got bounced as spam, so I'll try
it from here.]
Elton,
I am no expert in asteroid families, but possibly I can give a general
answer and cite a paper that may be of interest while we wait for a real
expert like Larry to respond.
A paper that I believe should be available to all online is:
"Impact origin of the Vesta family" by Erik Asphaug, published in
Meteoritics & Planetary Science 32,965-980 (1997)
http://onlinelibrary.wiley.com/doi/10.1111/j.1945-5100.1997.tb01584.x/pdf
I'm a bit busy validating NEO candidates at the moment so can't take the
time to read the entire paper, but in a nutshell Ashpaug discusses a
mechanism that created the Vesta family of asteroids about 10 - 100
million years ago.
While HEDs are almost certainly from Vesta the uncertainty about this
comes from the fact that we are sensing the surface from great distance.
When DAWN arrives, I'm sure the answer will become definitive and as I
mentioned in a previous thread, we may even be able to pinpoint where some
of our meteorites originated. Exciting stuff coming in the next few months
to be sure!
Most specifically to this question, that of other possible source parents,
it is my belief that this is unlikely. The formation of the Vesta family
was a major impact event. We certainly have not sampled spectroscopically
every asteroid, and I'm sure that we have not yet found every member of
the family, mostly due to size, brightness and circumstance. Small chunks
of Vesta in earth crossing orbits, say 10 meters in diameter, the size
that can drop tens of kilos on the earth's surface, are very difficult to
detect. In fact something this size may only be detected a few days before
impact, if at all.
It is my personal opinion that all HEDs can be traced back to Vesta and
most if not all "Vesta-like" V-type asteroids can be traced back to Vesta
as well.
More rocks coming through the pipeline, so that's all for now.
Cheers
--
Richard Kowalski
Catalina Sky Survey
Lunar and Planetary Laboratory
University of Arizona
http://www.lpl.arizona.edu/css/
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