[meteorite-list] Closure on the Lancaster, PA Event of 11-18-00

From: E.L. Jones <jonee_at_meteoritecentral.com>
Date: Thu Apr 22 09:37:32 2004
Message-ID: <3A308888.AD2B8B46_at_epix.net>

Hello List,

The short version: The impact was not meteoric but from an explosive
device.

The long version: This was a good practice for recovery of the real
thing.

BackGround:
Before Thanksgiving Holidays there was a news report and internet email
notice that a possible meteorite had landed on a car in Lancaster
Pennsylvania. After many delays, we dissected the dash of the car in
Lancaster, PA on Tuesday night which had a peculiar hole in its
windshield. It had its windshield and dashboard disrupted
--coincidentally-- during the Leonids shower around 3 AM (EDT) local the
Morning of
18 Nov. The proximity to a fireball sighting headed vertically down
over Lancaster and shape of the damage raised suspicion that this might
have been a meteorite impact. Initial inspection via various local
Police and Fire personnel failed to determine a positive identification
to the
cause. Being local to the area and having the most interest, it seems,
I was invited to participate in the search.

Search:
I joined the car owner, his family , and local planetarium personnel to
see if we could determine the cause of the damage. An external and
internal scan did not produce any large pieces of foreign material. I
conducted a scan with a magnifier over a portion of the windshield took
some samples of several magnetically attractive, dark shards. I looked
at them under my stereo microscope and they appeared to be shards of
tar/pitch -which has a glass-like, conchoidal fracture. The dash cover
had been removed, it too, showed no clearly meteoritic fragments.

Not finding anything meteoritic we moved to the inside. The car's
windshield and dashboard had been penetrated by an approximately 75-90°
down-angled force. A magnet probe into the well yielded nothing and
hopes of finding a meteorite were fading, if not confounding-- there
were no clear clues either way. Striations on the chrome trim but not
on the windshield were suspicious and later would be a contrasting clue.

 After enlarging the opening in the dash to gain access into the baffles
of the heater core housing, we located what appeared to be a crust-less
fragment of a bluish-gray material with tiny protruding
"chondrule-sized" bumps-- not unlike the Zag specimens I had brought
along for making
field comparisons. The brief moment of suppressed excitement faded as
the tweezers confirmed this was a sealant foam and not a wedged
meteorite in spite of the appearance. The whole floor of the
compartment was covered in sand-sized, glass particles. In fact, much of
it looked
just like mineral sand. At this point I was skeptical that we had a
meteorite but I could not yet rule out a very friable, high olivine, low
metallic
meteorite. So we continued looking and taking samples of the debris.

When extracting the tweezers they dislodged fragments of the culprit.
The unmistakable components* of a pyrotechnic in the Commercial
Pyrotechnic class, surfaced out of the sand. It still had the trace
odor of a burned composition like flash powder or black powder. A
minute
particle of tar removed from the windshield also tends to support that
this was a sealant used to waterproof the explosive. The striations
apparently came from the parts of the windshield wiper sheared away by
the blast and not mineral scratches. All the clues came together to
confirm that this was an explosive and not a meteorite impact.

I participated in post search newspaper interview as to what was found,
why it was a legitimate event to explore, the common misconceptions
about meteorites, and the need for public involvement in locating
meteorites and bringing them into science. I also hope we raised
awareness
of the 1995 New Holland, PA Fireball from which a meteorite should have
dropped but was never found.

Lessons Learned:
I thought we did a good methodical approach-- avoiding contamination,
preserving clues and going slow. Having the right tools for looking
into
crevices-- telescoping magnet, long tweezers, gooseneck flashlight,
inspection mirrors, lots of swabs and poly bags-- went a long way at
keeping the search clean. It was a good hands on opportunity for me to
expand my search techniques and to compare and contrast the
tell-tale clues of chemical and kinetic produced damage. ( Add to that
list survey flags and shovels in case it is over your creel size)

Everyone uses common words and we tend to interpret them within our own
frame of experience. This tends
to confuse investigators and raise speculation. It is important in
interviewing witnesses to bracket their statements between extremes or
contrasting options to make sure you are accurately envisioning the
witness's" real "experience. For example I did not see the "burning and

searing" which was first described in email reports. What I did see was
normal "shearing" and fractures in the windshield and stretching of the
plastic layer in the safety glass. I had to ask several times what the
"impact" sounded like. I finally asked was it a "kaboom" or a
"kuthump"....I
was told it sounded just like a car crash--like a transformer exploding!
.... At this point I knew we were talking about a "Kaboom" and not the
"Kuthump"-- A distinction which is important in accurate identification
between a chemical blast and a kinetic crash. My advice is to be aware
of
this quirk in the manner people describe things. Do not reach an early
conclusion because they have used a word or description which most of
the time will be slightly but distinctly different from your use of the
terms. Check'em ALL out.---Even "trained" observers can be the worse
culprits!

All persons reporting a possible meteorite are not hoaxers or
unsophisticated or unlearned people. This family was sincerely
interested in
finding the truth and not just finding a meteorite. This did pique their
interest in meteorites and I anticipate they will soon join the list and
the hobby.

Finally, for a long while I have wanted to challenge the use of
regmaglypts in our guides to discovering meteorites... The term is not
described
or illustrated sufficiently and meteorites tend to be more smooth than
bumpy. We really need to go revisit the way we tell the public how to
identify meteorites. I get photos frequently and can see how people
reach the conclusion that what they have is a "meteorite" when it is
clearly
not in the photo it matches some of the description.

Perhaps soon we can talk about the contents of a recovery/investigators
kit.

Regards,
Elton

*Because of a police investigation I was requested to refrain from a
full disclosure.
Received on Fri 08 Dec 2000 02:06:53 AM PST