[meteorite-list] ANOTHER QUESTION

[Sterling K. Webb]

Hi, Gerry, List,


> WHERE DO THEY
> COME FROM...???

    Despite having so many meteorite falls
observed, we have not enough information
from even many observations to determine
orbits for them. For that, you need a network
of full time observing stations with recording
radar and automatic cameras running all night
and spectrographs... expensive and elaborate.
    There have been such networks set up in
the past, but were eventually shut down due
to great cost and limited results. The first such
network was set up in Czechoslovakia and, in
1959, tracked the recovered PRIBEAM. It had
aphelion at 4.05 AU (the Hilda family of asteroids)
and perihelion at 0.79 (Venus) with eccentricity of
0.674. In all the other years this network ran, it
only successfully tracked one other item, an iron
which hit German forest country and was never
recovered.
    In the 1970's the Prairie Network in the USA
was established, which tracked and led to the
recovery of LOST CITY. Although it tracked
another dozen or so re-entries that probably
brought in a surviving chunk, none were ever
found. LOST CITY had an aphelion of 2.42
AU (densest past of the Zone) and a perihelion
of 0.97 AU (the Earth) with an eccentricity of
0.417. It too was shut down due to "costs."
And the Canadian network (MORP?) tracked
INNISFREE to recovery, but never recovered
another.
    All three of these spacerocks had aphelia
deep in the asteroid zone, all at places where
Jupiter could strongly perturb them. The great
meteoriticist Krinov worked out a pretty good
orbit for Sikhote-Alin that showed it came from
the Zone. The Great Grazer of 1972 (the Jackson
Hole Bolide) had several orbits worked out, but
all of them have it coming from the Zone.
    Face it, it's a bad neighborhood! It's like, they're
standing on an overpass and dropping rocks onto
the windshields of passing planets! Of course,
three examples of well-determined orbits are hardly
"proof" when there are many thousands of meteorites.
But on the other hand, if you rolled three sevens in
a row at craps, wouldn't you be surprised? (And,
if you CAN roll three sevens in a row at craps, we
need to talk...)
    So, we blythely assume most of them come from
The Zone. (My apologies for calling the Great Grazer
a "bolide," but magnitude -25 or -26, hey! You need
a special name! Especialy since it was nice enough
to miss us...)


Sterling K. Webb
---------------------------------------------------------------------
----- Original Message ----- 
From: "Gerald Flaherty" <grf2 at verizon.net>
To: "Chris Peterson" <clp at alumni.caltech.edu>; "Jeff Kuyken" 
<info at meteorites.com.au>; <meteorite-list at meteoritecentral.com>
Sent: Monday, November 20, 2006 1:06 PM
Subject: Re: [meteorite-list] ANOTHER QUESTION


> Chris my original question was directed to your claim that a fireball does
> not provide meteorites. I used the term bollide, perhaps inopportunely, to
> question the fact that if fireballs do not provide meteorites, WHERE TO 
> THEY
> COME FROM, witnessed or not???
> Jerry Flaherty
> ----- Original Message ----- 
> From: "Chris Peterson" <clp at alumni.caltech.edu>
> To: "Jeff Kuyken" <info at meteorites.com.au>;
> <meteorite-list at meteoritecentral.com>
> Sent: Monday, November 20, 2006 10:47 AM
> Subject: Re: [meteorite-list] ANOTHER QUESTION
>
>
>>A fireball is formally defined (by the IAU) as a meteor with an apparent
>> magnitude brighter than -4. Bolide isn't formally defined, and happily
>> its use seems to be falling out of favor in scientific publications (at
>> least, I see it used much less often lately than in publications from 10
>> years ago).
>>
>> Chris
>>
>> *****************************************
>> Chris L Peterson
>> Cloudbait Observatory
>> http://www.cloudbait.com
>>
>>
>> ----- Original Message ----- 
>> From: "Jeff Kuyken" <info at meteorites.com.au>
>> To: <meteorite-list at meteoritecentral.com>
>> Sent: Monday, November 20, 2006 12:24 AM
>> Subject: Re: [meteorite-list] ANOTHER QUESTION
>>
>>
>>> Hi Chris and all,
>>>
>>> I always thought 'fireball' was the technical term for a meteor with a
>>> negative magnitude. Is this correct?
>>>
>>> Cheers,
>>>
>>> Jeff
>>
>> ______________________________________________
>> Meteorite-list mailing list
>> Meteorite-list at meteoritecentral.com
>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
> ______________________________________________
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>