[meteorite-list] Bolivian university planetarium reports on Peruvian meteorite impact

From: Piper R.W. Hollier <piper_at_meteoritecentral.com>
Date: Tue, 25 Sep 2007 18:27:51 +0200
Message-ID: <6.2.1.2.2.20070925174626.03632e30_at_pop.xs4all.nl>

Hello list subscribers around the world,

The Max Schreier Planetarium at Mayor San Andres University in La Paz,
Bolivia posted a three-page paper (in Spanish) yesterday summarizing what
is known to date about the new crater or impact pit at the edge of
Carancas, Peru (estimated diameter 13 to 17 meters) and the space rock that
created it on September 15:

http://fcpn.umsa.bo/fcpn/app?service=external/PublicationDownload&sp=229

My grasp of the Spanish language is far from 100%, but I couldn't find any
new surprises here. The report does seem to have been written by someone
with some scientific knowledge of meteorites and impact physics, and thus
appears to be relatively free of the gratuitous inaccuracies and
sensationalism that many of the recent media reports have been tainted with.

Here is a rough translation of one section of the report:

In the case of the impact that happened on Saturday, September 15, we know
by a superficial analysis of small specimens that were collected that the
meteorite that fell in Huanucollo is of the stony type, specifically a
chondrite, that is to say to a meteorite rich in silicate in the form of
small spherules or chondrules (whence the name chondrite), with an iron
content whose amount has not yet been determined. This allows us to have
greater knowledge about the identity and history of our visitor, thus for
example, we can assume that this meteorite was part of the surface of an
asteroid that was removed long ago, perhaps by the impact with another
asteroid. From the type of meteorite, we can also presume that its entrance
into the terrestrial atmosphere was very rough, as generally this type of
meteorite is too fragile, fractures immediately, and if they manage to
arrive at the surface, they do it in the form of fragments. Stony
meteorites are not known that surpass a mass of two tons; the greatest of
stony meteorites found is the Jilin mass that holds the record of 1.77
tons, in comparison to meteorites of the ferrous type (iron compounds
mainly), whose masses easily reach the tens of tons, as is the case of the
Hoba meteorite of more than 60 tons. Because it is common that a stony
meteorite like that which fell in Huanucollo does not survive the impact,
one can say that it is not very probable that there is a mass of meteorite
buried underneath the crater that formed. To have arrived at the surface
and to have formed that crater, the meteorite must necessarily have entered
the terrestrial atmosphere almost perpendicular to the surface and at a
slow speed (we estimate about 17 km/s). And in addition, it must have had
an aerodynamic form, that is to say, it had to be slightly flattened.

Best wishes to all,

Piper Hollier
Amsterdam NL
Received on Tue 25 Sep 2007 12:27:51 PM PDT