[meteorite-list] Scientists Size Up, Classify Park Forest Meteorite

From: Walter Branch <branchw_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:14 2004
Message-ID: <000101c42261$41fd2de0$1622dc44_at_wbranch>

Hello Everyone,


"The meteorite broke up in the atmosphere, and the fragments encountered
strong westerly winds as they fell," the authors write. "The smallest pieces
were deflected the furthest eastward from the trajectory, and the largest
pieces, carrying more momentum, were deflected the least."

Now that is interesting. the wind blew the smaller pieces at a right angle
to the trajectory. I have sometimes wondered is this were possible. Now I
know.

Wasn't there quite a bit of discussion last year about the altitude at the
which the breakup occurred? Seems like different people were getting
different altitudes. Maybe these winds were affecting the calculations in
different ways?

-Walter

------------------------------------------
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----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Wednesday, April 14, 2004 1:16 PM
Subject: [meteorite-list] Scientists Size Up, Classify Park Forest Meteorite


>
>
> Scientists Size Up, Classify Meteorite That Nearly Landed in Their
Backyards
> AScribe Newswire
> April 14, 2004
>
> CHICAGO -- The meteorites that punched
> through roofs in Park Forest, Ill., on the evening of March 26, 2003, came
> from a larger mass that weighed no less than 1,980 pounds before it hit
the
> atmosphere, according to scientific analyses led by the University of
> Chicago's Steven Simon, who himself also happens to live in Park Forest.
>
> Simon, a Senior Research Associate in Geophysical Sciences at the
> University of Chicago, and seven co-authors will publish these and other
> findings in the April issue of the journal Meteoritics and Planetary
> Science. Simon holds a unique distinction among scientists: his home sits
in
> the middle of the strewnfield, the area from which the meteorites were
> recovered.
>
> "I don't know of any other time when a meteoriticist was in the
> middle of a strewnfield," said Lawrence Grossman, Professor in Geophysical
> Sciences at the University of Chicago and one of Simon's co-authors.
>
> In fact, Simon actually saw the flash the meteorite created. He had
> the drapes closed when the rock entered the sky over Illinois, but "the
> whole sky lit up," he said.
>
> Grossman, who lives in Flossmoor, not far from Park Forest, also
> experienced the meteorite's arrival firsthand. He was awakened by the
sound
> of the meteorite entering the atmosphere that night. "I heard a
detonation,"
> Grossman said. "It was sharp enough to wake me up."
>
> The team calculated the projectile's size range based on measurements
> of the galactic cosmic rays that it absorbed. Measurements of a
radioactive
> form of cobalt provided the projectile's minimum size. "If the object is
too
> small the cosmic rays will just pass through and not make cobalt," Simon
> explained.
>
> Simon and Grossman classify the meteorite as an L5 chondrite, a type
> of stony meteorite, one low in iron that was heated for a long period of
> time inside its parent body, probably an asteroid. "It's a fairly common
> type of meteorite," Simon said.
>
> The Park Forest meteorite also showed signs that it had been highly
> shocked, probably when it was part of a rock that was broken from a much
> larger asteroid following a collision. The evidence for shock includes
> shocked feldspar. Apollo astronauts recovered shocked specimens of the
> mineral from the moon, as well, Simon said. Impact shock was common in the
> early history of the solar system because of the large quantity of
> interplanetary debris then in existence.
>
> Witnesses in Michigan, Illinois, Indiana and Missouri reported seeing
> the fireball that the meteorite produced as it broke up in the atmosphere,
> Simon and his colleagues report. Local residents collected hundreds of
> meteorite fragments totaling approximately 65 pounds from an area
extending
> from Crete in the south to the southern end of Olympia Fields in the
north.
> Located in Chicago's south suburbs, "This is the most densely populated
> region to be hit by a meteorite shower in modern times," the authors
write.
>
> One meteorite narrowly missed striking a sleeping Park Forest
> resident after it burst through the ceiling of a bedroom. The meteorite
> sliced through some window blinds, cratered the windowsill, then bounced
> across the room and broke a mirror before coming to rest.
>
> The meteorites were recovered from a track that trends southeast to
> northwest. Satellite data analyzed by Peter Brown of the University of
> Western Ontario indicates that the meteorite traveled from southwest to
> northeast, however.
>
> "The meteorite broke up in the atmosphere, and the fragments
> encountered strong westerly winds as they fell," the authors write. "The
> smallest pieces were deflected the furthest eastward from the trajectory,
> and the largest pieces, carrying more momentum, were deflected the least."
>
> Contributing to the paper in addition to Simon and Grossman were the
> University of Chicago's Robert Clayton and the late Toshiko Mayeda, Jim
> Schwade of the Planetary Studies Foundation in Crystal Lake, Ill.; Paul
> Sipiera of Harper College in Palatine, Ill.; John Wacker of Pacific
> Northwest National Laboratory in Richland, Wash.; and Meenakshi Wadhwa of
> the Field Museum of Natural History in Chicago.
>
> Their research was supported by grants from the National Aeronautics
> and Space Administration, the National Science Foundation, and the
Planetary
> Studies Foundation.
>
>
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Received on Wed 14 Apr 2004 02:43:59 PM PDT