[meteorite-list] Bolides and Portales Valley

From: Robert Woolard <meteoritefinder_at_meteoritecentral.com>
Date: Tue Jan 17 13:51:44 2006
Message-ID: <20060117185124.25554.qmail_at_web32909.mail.mud.yahoo.com>

Hello Bernd, Chris, and List,

  Great info, as always, Bernd, and Chris. If you
don't mind, I'd like to ask you (or any other members)
about another meteorite that I must admit I am a bit
"partial to".

  Does anyone have any idea as to the
calculated/predicted original mass and size of the
Portales Valley meteoroid? I have read all the
articles that I can find on PV, and have only found
one reference that stated it was at "LEAST" 60cm, or ~
2 feet, in diameter.

  I have always felt that this seemed a little too
small for such a dramatic, daytime fireball. And,
since it was an early morning event and thus ran head
on into the Earth, the ablative forces would have been
even greater, correct? Yet, the total recovered weight
is ~ 110 Kg ( not the almost universally reported 67
Kg which did not take into account several specimens,
including the 34 Kg main mass). I am definitely no
expert on all the relative calculations involved here,
but I was "under the general impression" that an early
morning encounter usually resulted in very high
ablation loss (maybe even 90% or greater????). IF that
is anywhere near right, am I correct in feeling that a
TKW of ~ 110 Kg seems to be too great for an original
meteoroid only 60cm in diameter??

  (One other quick fact, just for fun, about PV that I
have always found interesting is that the specific
gravity for the individuals recovered ranged from 2.45
- 4.75 g/cm3.)

  Thanks to Bernd, Chris, or anyone, who can help me
with this question.

  Best wishes,
  Robert Woolard
  http://www.portalesvalleymeteorites.com
  IMCA #8103


--- bernd.pauli_at_paulinet.de wrote:

> Pete asked:
>
> If this is a worthwhile question, how about
> Peekskill, which so many of us
> witnessed - how large would that have been at the
> start of its descent?
>
> Chris wrote:
>
> Peekskill...an initial mass of about 10 tons,
> so...an almost 2 meter diameter.
>
> Hello List,
>
> Graf et al. (1994) Size and exposure history of the
> Peekskill meteoroid
> (Meteoritics 29-4, 1994, A469): Both values (=
> measured 26Al activities)
> are consistent with a preatmospheric radius of ~50
> cm.
>
> Ceplecha Z. et al. (1994) Video observations of the
> Peekskill H6 meteorite
> fireball - Atmospheric trajectory and orbit
> (Meteoritics 29-4, 1994, A455):
>
> a) ...an initial mass of the order of 10^?4 kg and
> with initial velocity of 14.7 km/s
>
> b) The dark flight of the recovered meteorite
> started from a height of 30 km, when
> the velocity dropped below 3 km/s, and the body
> continued an additional horizontal
> distance of 50 km without ablation, until it hit
> a parked car in Peekskill, NY, with
> a vertical velocity of about 80 m/s.
>
> Graf et al. (1997) Exposure history of the Peekskill
> (H6) meteorite
> (Meteoritics 32-1, 1997, 25-30):
>
> [We] conclude that Peekskill's radius was less than
> 70 cm when it entered the Earth's
> atmosphere. This size limit is somewhat smaller than
> the photometric determinations
> (Brown et al., 1994).
>
>
> Best wishes,
>
> Bernd
>
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Received on Tue 17 Jan 2006 01:51:24 PM PST