[meteorite-list] Mbale

From: Jan Bartels <jan_at_meteoritecentral.com>
Date: Wed, 16 May 2007 22:07:34 +0200 (CEST)
Message-ID: <1887.213.84.146.142.1179346054.squirrel_at_webmail.uniserver.nl>

Oh Yeah Holland rules with the Mbale fall.
Only to bad we still keep that, about 140 kilos, away from human eyes
because we still believe here that human eyes may damage the fusion crust
of meteorites.
Holland sucks (sorry) concerning meteorites.
When you ever visit the largest Natural History museum here you realy need
to ask where they keep their meteorites. Most of them are hidden in
cabinets in drawers. Oh no wait...there's a plexiglass tube holding about
five or six to view !!
If we would'nt have put our private collection on display at our local
observatory, which i suggest is now the largest on display in Holland,
there would have been nothing. Lucky enough there were many more kilos of
Mbale recovered after the Dutch went back with there trophy, thinking we
had the whole thing, otherwise we all had to guess how Mbale would look
like.

Sorry....just gives me curly toes when this topic cmes up.

Night all,
Jan & Yvonne
Holland
www.heavenlybodies.nl


Hi AL, Martin and all,

> There was a good article about the fall in S & T with good photos.

Best regards,

Bernd

Sky & Telescope, June 1983, pp. 96-97
Amateur Astronomers, Edited by Stephen James O'Meara

On August 14, 1992, a daytime shower of stony meteorites rained down on
Mbale,
Uganda, and its surroundings. Clockwise from left: These Ugandan soldiers
collected
two fragments with weights of 6.2 and 3.0 kilograms, respectively. Three
men from the
tiny village of Malukhu found a 10.8-kg fragment that made an 85-cm-deep
hole when
it hit. A sample of meteorites recovered from the Mbale fall and outlying
regions; the total
weight of these fragments exceeds 40 kg. All photographs, unless credited
otherwise, are
by Jan L. Betlem, Mount Elgon Conservation and Development Project.


The Day That Rained Stones

On the afternoon of August 14, 1992, citizens of Mbale, Uganda, witnessed
a large explosion
in the sky, out of which emerged a shower of flaming meteorites. For
minutes the fragments
rumbled as they blazed smoky trails across the heavens. Villagers farther
north thought they
were being bombed by rebels, since conflicts were occurring only a few
tens of kilometers
away - in the direction from which the objects came! Adding to the
confusion, the explosion
produced a sonic boom that sounded like machine-gun fire. Minutes later
stones showered
the Earth.
The next day Jan L. Betlem of the Mount Elgon Conservation and Development
Project in
Mbale informed the Dutch Meteor Society of the fall. On August 25th I
arrived in Africa with
fellow meteor-society members to interview eyewitnesses and study impact
sites. Already the
police had inherited a fine collection of fragments, one of which weighed
about a kilogram.

For a week we carried out fieldwork with geologists Thomas Schl?ter and
Erasmus Barifaijo
(Makarere University of Kampala, Uganda) and local authorities. Police
also assisted, leading
us to several buildings hit by meteorites in Mbale's industrial area.
During our inspection we
also found several other impact sites.
To date we know of about 50 impacts. Two major ones took place in the
swamps south of a
prison. In fact, four fragments fell near or hit the prison itself. The
largest, weighing at least 10 kg,
landed only one meter from a building near the prison and made a
depression 80 centimeters deep.

Two meteorites smashed into a railway station; one broke through its roof
and shattered on the
concrete floor. Another impact occurred at a Shell Oil Co. storage
facility. The stone, weighing
a few kilograms, fell atop an underground fuel tank; fortunately it
produced a hole only a few tens
of centimeters deep. Another major fragment weighing about 5 kg pierced
the roof of a cotton
factory, hit a machine, and shattered into several piece. Impacts were
also reported at a coffee
factory and a sewage works northwest of Mbale.
Smaller fragments were found in Doko, about 5 km northwest of Mbale, where
we recovered
many stones weighing a few grams. As far as we know, no one was injured
during the falls
- incredible considering the dozens of meteorites that must have rained
down on that densely
populated area. A 4-gram fragment did hit a boy from Doko on the head, but
he was not hurt.

The meteorites speak

About 300 kg of meteorites fell on Mbale and its environs. Although we
probably recovered all
of the major fragments, many of the smaller stones might still lie at the
bottom of the extensive
swamps surrounding the city; these might never be recovered. The weight of
the collected
fragments ranged from 0.1 gram to several tens of kilograms.

The Mbale meteorites are now being studied in the Netherlands. Initial
research by C.E.S. Arps,
director of mineralogy at the National Museum of Natural History in
Leiden, indicates that they
are L6 type chondrites - stony objects low in iron with microscopic flecks
of magnesium-iron
silicates. Larger fragments show thin, annealed fractures, implying that
the final breakup took
place high in the sky. In fact, nearly all of the 300 recovered fragments
have a black fusion crust.

Eyewitness accounts of the explosion are sketchy, mainly because it
occurred high in the sky near
the Sun. We believe that the final breakup occurred about 10 km north of
the major impact sites
we inspected. The fireball's flight angle and duration, however, are still
very uncertain. By weighing
the fragments and studying the impact sites further we hope to learn more
about the parent body's
course.

HANS BETLEM, Dutch Meteor Society, Lederkarper 4, 2318 NB Leiden, The
Netherlands


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Received on Wed 16 May 2007 04:07:34 PM PDT