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
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----- Original Message -----
From: "Darren Garrison" <[EMAIL PROTECTED]>
To: <[email protected]>
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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