[meteorite-list] Carancas in the news

Tue Feb 26 17:47:11 EST 2008

Hi, All,

    The papers on Carancas referred to are this one...
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1216.pdf

    ...and this one:
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2446.pdf

    The first paper suggests, by an analysis of witness reports
from the surrounding area, an azimuth of 82° and an altitude
of 63°  for the incoming trajectory, with an impact velocity of
3000 m/sec. Orbital calculations based on this track suggest
a body of low inclination (<5° ) but in an orbit very different
from known near-Earth asteroids.

    An unique, or at least odd, object, with an unique, or at least
odd, orbit. It came from somewhere else, folks... Its strange
appearance and texture show a very heavily shocked history.

    The second paper, which studies the impact effects on the
materials of the locality, suggests that many of the shock features
mean a greater impact velocity, perhaps 4000 m/sec or more.

    Their analysis of the stratigraphy of the crater suggests that
the "bolide" reached the ground in one piece and penetrated
intact to the depth of about 1/3rd of a meter before "exploding."
Large overturned blocks of ejecta are "riddled" (their word)
with meteoritic fragments ON THE UNDERSIDE.

    Both papers are short and sweet (2 pages) and they are worth
the read.

    We've been having this discussion on the List about the
List, and the Carancas story is a perfect example of the virtues
of the List and what it can do in its informal way. The suggestion
that the "boiling" and odors of the crater were due the thermal
dissociation of troilite (which is abundant in the meteorite) was
first made here on the List (and first made anywhere) by member
Piper R. W. Hollier.

    From that, others were able to calculate that the impact
velocity had to be in excess of 1611 m/sec, probably at least
twice that, to vaporize the troilite -- a figure that matches that
calculated in the first paper cited above.

    There were arguments presented for a high altitude angle
for the impact (later determined to be 63°) and for an orbit like
that suggested in that first paper. In fact, a good deal of this
information about Carancas presented in these papers could
be found, in somewhat more speculative form, on the lengthy
and voluminous List discussion of Carancas in the first weeks
after the event.

    There was nothing else like this List discussion of Carancas
going on anywhere else and no other place where information
could be found, sifted, and analyzed, or witness reports could
be found. There was even a good explanation of how the
"bolide" managed to get to the ground in defiance of "the
models" which all say, no way.

    All I'm saying here is: "Hooray for the List." There's
nothing else like it.

Sterling K. Webb
--------------------------------------------------------------------------------
----- Original Message ----- 
From: "Darren Garrison" <cynapse at charter.net>
To: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, February 26, 2008 10:24 AM
Subject: [meteorite-list] Carancas in the news

http://cosmiclog.msnbc.msn.com/archive/2008/02/25/701427.aspx

Meteorites spark mysteries Posted: Monday, February 25, 2008 8:20 PM by Alan
Boyle

Five months after a meteorite made an international splash in Peru, experts 
are
suggesting explanations for some of the space rock's effects - for example, 
the
sickening odor villagers smelled at the crash site, and the bubbles that 
were
seen emanating from the water-filled crater left behind. But a study due to 
be
presented next month also raises fundamental questions about the event. In 
fact,
an international research team declares that the impact "should not have
happened" at all.

Yet another study sets forth a mystery surrounding two other meteorites 
found in
Antarctica a couple of years ago. The rocks don't match any other class of
meteorite - so where did they come from?

The two studies are among hundreds submitted for the annual Lunar and 
Planetary
Science Conference, scheduled March 10-14 in League City, Texas. The 
conference
offers the cream of the crop in planetary science - focusing on topics 
ranging
from the solar wind, to Mercury and Mars, to the icy dwarfs on the solar
system's edge.

The Peruvian meteorite impact comes in for a fresh round of scientific 
scrutiny
in a study submitted by researchers from Brown University and institutes in 
Peru
and Uruguay. Just after the impact was reported, some scientists doubted 
whether
a meteorite was actually responsible for the crater - but subsequent 
analysis
proved that a stony space rock was involved (as opposed to a denser iron
meteorite).

Scientists previously thought that stony meteorites on the scale of the one 
that
hit Peru would break apart into little pieces before they hit the ground. 
The
fact that this one survived to create a 40-foot-wide crater threw the
researchers what they called a "hypervelocity curveball." They said the 
standard
model used to estimate the effects of stony meteorites will need to be 
revised
as a result.

The study does propose two possible explanations for the reports of "boiling
water" seen within the crater: The bubbles could have come from the 
compressed
air that surrounded the meteorite as it blasted into the wet earth - or it 
could
have been caused by clumps of clay that dissolved and frothed as they fell 
into
the crater.

"These two processes may have been responsible for local reports of water
bubbling up from the floor soon after impact," the researchers wrote. "While
there would have been heat generated at impact, it is unlikely that this 
could
have sustained bubbling an hour later."

Meteorite hunter Michael Farmer, who visited the site last year soon after 
the
impact, has said the sickening odor that villagers said emanated from the 
crater
was most likely caused by sulfurous compounds such as triolite interacting 
with
the ground water - and there's nothing in the latest study that contradicts 
that
suggestion.

The Peruvian meteorite may be in for another shot at fame: Just last week,
Living in Peru reported that Japanese investors are interested in building a
space museum near the impact site, and that National Geographic is planning 
a
documentary about the meteorite.

Now to the other space-rock study: Meteorite hunters from the Lunar and
Planetary Institute and NASA's Johnson Space Center reported finding a pair 
of
specimens in 2006 in Antarctica's Graves Nunataks area.

"These meteorites are not obviously like any other meteorites, so their 
origin
is unclear," the Lunar and Planetary Institute said in its media advisory. 
"The
mineralogy and chemical composition of these meteorites are so unusual that
scientists have been struggling to find the right term to describe them.
Numerous parent bodies have been proposed. Could they have come from the 
moon?
>From Venus? Scientists are currently debating these issues."

The researchers behind the study say they're not finished with their 
analysis of
the rocks, and more findings may emerge at next month's conference. So stay
tuned as the meteorite tales and other mysteries are fully brought to light.
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