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(meteorobs) Excerpts from "CCNet 104/2000 - 16 October 2000"




------- Forwarded Message

From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet, 16 October 2000
Date: Mon, 16 Oct 2000 12:05:38 +0100

CCNet 104/2000 - 16 October 2000 
--------------------------------

[...]

(2) LOS ALAMOS ARRAY DETECTS LARGE, BRIGHT METEOR OVER NEW MEXICO
    Ron Baalke <baalke@jpl.nasadot gov>

(3) KANSAS FIREBALL
    Mark Kidger <mrk@ll.iac.es>

(4) SUSPICIOUS LIGHTS IN THE SKY PROVE HARMLESS
    Wichita Eagle, 14 October 2000

(5) TAGISH LAKE METEORITE MAY BE MOST PRIMITIVE SOLAR SYSTEM MATERIAL EVER
STUDIED 
    THE UNIVERSITY OF WESTERN ONTARIO/UNIVERSITY OF CALGARY

(6) FIREBALL IGNITES SCIENTIFIC CURIOSITY
    BBC Online News, 13 October 2000

[...]

(11) PHYSICAL PROPERTIES OF PHAETHON
     Alan Harris /DLR, Berlin <Alan.Harris@dlrdot de>


======================================================================

(2) LOS ALAMOS ARRAY DETECTS LARGE, BRIGHT METEOR OVER NEW MEXICO

>From Ron Baalke <baalke@jpl.nasadot gov>

http://www.lanldot gov/external/news/releases/archive/97-155.html

Los Alamos National Laboratory
News Release

CONTACT: James E. Rickman, 505-665-9203 (97-155)

- ----------------------------------------------------------------------------

Los Alamos array detects large, bright meteor: Laboratory researcher joins
the search

LOS ALAMOS, N.M., Oct. 10, 1997 - Researchers at Los Alamos National
Laboratory were able to use an array developed to listen for clandestine
nuclear weapons tests to help locate a large meteor that flashed in the sky
Thursday afternoon above Southern New Mexico.

The object -- presumably a large, bright meteor known as a bolide -- was
seen in the skies Thursday at about 12:47 p.m. Witnesses said the object was
at least as bright as the full moon or as bright as the setting sun.

"The meteor made a huge sonic signal," said Doug ReVelle, a meteorologist in
Los Alamos' Atmospheric and Climate Sciences Group. "They heard it like a
freight train in El Paso."

Using data from Los Alamos listening stations originally set up to monitor
nuclear explosions, ReVelle and other researchers in Los Alamos' Atmospheric
and Climate Sciences Group analyzed the infrasonic signature created when
the meteor entered the atmosphere.

When a meteor enters the atmosphere -- or when a large explosion is
detonated -- it creates a sound or pressure wave that is below the range of
human hearing. This infrasonic wave travels through the atmosphere and can
be detected by special microphones that are set up in an array. By looking
at the time of arrival of the sounds at different stations and the frequency
of the infrasonic boom, researchers can pinpoint the location of the source
and the determine the amount of energy that created it.

"The data from our array puts the meteor 441 kilometers due south of Los
Alamos," said ReVelle. "We'll be looking for it in a location we've
identified near El Paso."

ReVelle will join researchers from Canada, the University of New Mexico and
Sandia National Laboratory on a search this weekend for any meteor fragments
that may have reached the ground.

"The object's infrasonic signature was equivalent to the explosive yield of
about 500 tons of TNT," ReVelle said. "That means the object was somewhere
around one half to three-quarters of a meter in diameter."

Thanks to the infrasound array at Los Alamos, researchers at the Laboratory
were able to narrow down the location where it may have landed pretty well.

In addition to searching for remains of the meteor -- which may have
exploded into tiny bits in the sky - the researchers will interview
witnesses about the object: how bright it was; what it sounded like.

The object created a brilliant light as it streaked toward Earth. Witnesses
in Santa Fe, Los Alamos, Albuquerque, El Paso and points in between saw the
object in the sky.

ReVelle and the others will search all weekend for the object and collect
other data as well.

"It could take weeks to find, but it could take a day or less, depending on
how lucky we get," ReVelle said.

Infrasonic waves are very low frequency sounds that exist somewhere in the
realm between hearing and meteorology, ReVelle said. The sounds are well
below the range of human hearing, which ends at about 30 hertz, but actually
can be detected as small changes in atmospheric pressure. If someone had a
barometer that was sensitive enough, that person would be able to see
fluctuations of several microbars when infrasonic waves arrive.

During the 1960s and early 1970s, before the rise of the satellite era, the
United States Air Force operated a network of stations to listen for nuclear
weapons tests. The listening stations were the nation's first line of
detection for nuclear explosions worldwide.

The four arrays of listening stations operated by Los Alamos are the only
infrasonic network left in full-time operation in the world. They can detect
meteors that are as small as a few centimeters in diameter. The stations are
useful because they can help validate other non-proliferation and
verification techniques, and they cost very little to operate and maintain.

The Los Alamos stations, around since 1983, still are enlisted in the
nation's nuclear non-proliferation efforts, but have provided a way for
scientists to detect bolides, larger-than-average space debris that slams
into Earth's atmosphere and creates brilliant fireballs in the sky.

Each year a number of large meteors enter the atmosphere and are detected by
the Los Alamos array. Some meteors are tens of meters in diameter. ReVelle
said each year about 10 meteors that are two meters in diameter - with an
energy equivalent of a one-kiloton blast - enter the atmosphere. Most burn
up or explode in brilliant flashes. Some hit the ground.

For this weekend's search, ReVelle will join Peter Brown of the University
of Western Ontario; Alan Hildebrand from the National Research Council in
Ottawa, Ontario; a researcher from University of New Mexico's Institute of
Meteoritics; and Mark Boslough of Sandia National Laboratory.

Los Alamos National Laboratory is operated by the University of California
for the U.S. Department of Energy.

======================================================================

(3) KANSAS FIREBALL

>From Mark Kidger <mrk@ll.iac.es>

Benny:

You may be interested in running something on the big Kansas fireball seen
just
after sunset last Friday. You can find it on:

http://www.meteors.com/cometlinear/index.shtml

Several updates on the story are due later today as the 8 hour time
difference
with California meant that they came too late to be included last night or
this
morning. There is a suggested identification with a Russian Glonass
satellite.

Mark

======================================================================

(4) SUSPICIOUS LIGHTS IN THE SKY PROVE HARMLESS

>From Wichita Eagle, 14 October 2000
http://web.wichitaeagle.com/content/wichitaeagle/2000/10/14/localnews/

Officials say the fireballs were probably a large meteor breaking up or
"space junk." 

By Novelda Sommers
The Wichita Eagle

Those weren't alien spacecraft that streaked across the sky Friday night
over Wichita.
The fireballs that left glowing trails of smoke lingering in the heavens
were likely caused by a meteor that broke up as it entered Earth's
atmosphere, said Greg Novacek, director of the Lake Afton Public
Observatory.

Hayden Frank, a meteorologist with the National Weather Service, said he
thought the lights were caused by "space junk" entering the atmosphere.

The lights moved over Sedgwick County just after sunset Friday, putting on a
show for startled residents.

Lt. Bret Giffen of the Wichita Police Department's south substation, said
callers inundated emergency dispatchers about 7:30 p.m., reporting what some
thought was a plane crash and what others described as "a fire in the sky." 

FULL STORY at
http://web.wichitaeagle.com/content/wichitaeagle/2000/10/14/localnews/

======================================================================

(5) TAGISH LAKE METEORITE MAY BE MOST PRIMITIVE SOLAR SYSTEM MATERIAL EVER
STUDIED

>From THE UNIVERSITY OF WESTERN ONTARIO / UNIVERSITY OF CALGARY
http://www.ucalgarydot ca/unicomm/NewsReleases/meteor_00.htm

Dennis Urquhart
Research Communications
(403) 220-7722

METEORITES MAY BE MOST PRIMITIVE SOLAR SYSTEM MATERIAL EVER STUDIED

Researchers at The University of Western Ontario (Western) and the
University of Calgary (U of C) -- working with colleagues from Canada,
the United States and the United Kingdom -- have found that meteorites
recovered in northern British Columbia may be one of the most primitive
solar system materials ever examined.

Peter Brown, a professor in Western's Department of Physics and
Astronomy, and Alan Hildebrand, a professor in the Department of Geology
and Geophysics at U of C, are the lead authors of the report featured on
the cover of the Oct. 13, 2000 issue of the international journal Science.

The meteorites, recovered by B.C. resident Jim Brook in late January, and
scientists at Western and the U of C during April and May, were found on
Tagish Lake, B.C. It was the largest meteorite fall in Canadian history.

"We can now say that this may be the 'crown jewel' of meteorite finds,"
says Brown. "This discovery will aid scientists in the reconstruction of
the early solar system." 

"The standard composition of the solar system is partly defined by the
most primitive meteorite in existence," says Neil MacRae, earth sciences
professor at Western and a co-author on the Science paper. "If our results
are proven correct, this new discovery will ultimately change that
definition."

The Tagish Lake Meteorite is a new type of carbonaceous chondrite -- a
rare, organically rich, charcoal-like class of meteorites. Carbonaceous
chondrite meteorites make up about three per cent of meteorite finds in
the world. The chemical class most closely resembling this meteorite
constitutes less than 0.1 per cent of all meteorites recovered to date,
though the Science paper suggests the Tagish Lake Meteorite to be even
more primitive and therefore may represent a new class. 

The first recovered pieces of the Tagish Lake Meteorite have been kept
frozen, which will allow researchers to identify the full range of
compounds in a primitive, carbon-rich meteorite for the first time.
These organic materials may help scientists better understand chemical
processing in the outer part of the solar nebula. The meteorite is also
rich in interstellar grains. Coupled with the limited aqueous alteration
on the parent asteroid of the Tagish Lake Meteorite, this may mean that
new things will be learned about the nuclear furnaces of stars. 

"The most significant and exciting things to be discovered in this
meteorite may not yet be known," says Hildebrand. "We, together with
Jim Brook, are supplying material to dozens of researchers located around
the world for their studies. It is a delightful and somewhat rare situation
for scientists when we can't predict what may be learned." 

Other members of the research team include Michael Mazur, Tina
Rubak-Mazur, Michael Glatiotis, and J. Andrew Bird at U of C; Michael
Zolensky at NASA Johnson Space Center; Monica Grady at the Natural
History Museum in England; Robert Clayton and Toshiko Mayeda at the
University of Chicago; Edward Tagliaferri at ET Space Systems in
California; Richard Spalding of Sandia National Laboratories in New
Mexico; Margaret Campbell, Robert Carpenter, Heather Gingerich, Erika
Greiner, Phil McCausland and Howard Plotkin at Western; Eric Hoffman
at Activation Laboratories Ltd. in Ancaster, Ontario; David Mittlefehldt
at Lockheed Engineering and Science Co. in Houston; and John Wacker at
the Pacific Northwest National Laboratory, Richland, Washington.

- -------

For more information, please contact:

Peter Brown at (519) 661-2111 ext. 86458
and
Alan Hildebrand at (403) 220-2291 or cell (403) 874-1434

For B-roll footage, a copy of the Science paper or to arrange interviews,
please contact:

Marcia Daniel
Communications and Public Affairs, The University of Western Ontario
(519) 661-2111 ext. 85468
or
Dennis Urquhart
Research Communications, University of Calgary
(403) 220-7722

For photos, biographies, backgrounders and video footage, please visit the
following websites:

* http://phobos.astro.uwodot ca/~pbrown/tagish/
* http://comms.uwodot ca/media/releases/releases2000/May%2031b.htm
* http://www.ucalgarydot ca/unicomm/meteor/photos.htm
* http://www.geo.ucalgarydot ca/cdnmeteorites/

Attention broadcasters: The University of Western Ontario has installed
Bell's VideoROUTE service that allows for live or pre-taped broadcast
interviews with television studios. For more information, please call
(519) 661-2111 ext. 85468 or ext. 85165.

======================================================================

(6) FIREBALL IGNITES SCIENTIFIC CURIOSITY

>From the BBC Online News, 13 October 2000
http://news.bbc.codot uk/hi/english/sci/tech/newsid_968000/968749.stm

By BBC News Online science editor Dr David Whitehouse 

Scientists have revealed new data about a meteorite that could be one of the
most primitive Solar System objects yet studied. 

The space rock was recovered from the frozen Tagish Lake in Canada. The
meteorite has aroused huge excitement among researchers because its
fragments could help us understand better how the planets were formed. 

The rock fell to Earth on 18 January, 2000. The exceptionally long and
bright fireball was seen throughout the Yukon, Northern British Columbia,
parts of Alaska, and the Northwest Territories. 

Several dozen pieces of it have been retrieved. Importantly, the pieces were
picked up still frozen, providing researchers with a unique opportunity to
study organic compounds that may even have been the building blocks of life
on Earth. 

The Tagish Lake meteorite is a so-called carbonaceous chondrite, a rare type
of ancient meteorite that makes up only 2% of all meteorite finds. Unlike
most rock found in the Solar System, it has not been changed by major
heating sometime in its history and as such allows researchers a chance to
study the very stuff that came together to form the Sun and the planets. 

Analysis of the Tagish Lake meteorite, reported in the journal Science by
Peter G Brown at the University of Western Ontario, Canada, and colleagues,
suggests the rock may represent a completely new class of carbonaceous
chondrite, more primitive than any yet found. 

Using eyewitness accounts, photographs, videos, and satellite data of the
rock's fiery and dramatic entrance into the Earth's atmosphere, the
researchers have also calculated where the meteorite came from. 

Its trajectory indicates that the space rock originated from the middle of
the asteroid belt which lies between the orbits of Mars and Jupiter (about
300 million to 600 million kilometres/186 million to 370 million miles from
the Sun). 

Many researchers want to study the unique meteorite

Analysis of the carbon in Tagish Lake indicates that some of it is in the
form of so-called nanodiamonds, tiny particles of interstellar material that
were in the solar nebula, the cloud of gas and dust that came together to
form the Solar System. Tagish Lake may be richer in interstellar grains than
any meteorite studied before. 

Jeffrey Grossmann of the US Geological Survey says that Tagish Lake is the
most significant meteorite to come into the hands of scientists since the
well-known Allende meteorite from Mexico and the Murchison meteorite from
Australia, both of which were picked up in 1969. 

Alan Hildebrand of the University of Calgary, Canada, says that the best
indication of the significance of the Tagish Lake recovery can be seen in
the receipt of dozens of requests from meteorite researchers around the
world to study the new rock. 

Many small fragments have now been recovered

One very interesting aspect of the Tagish Lake study is the compilation of
detailed eyewitness accounts of the fireball. 

Many people noticed smells at the time of the rock fall. These were
frequently described as sulphurous, although hot metal and rock were also
mentioned. And these smells were picked up by people many tens of kilometres
from the drop zone. 

About one in 10 also reported sound instantaneous to the fireball event. It
might seem impossible that a noise can be heard concurrent with an object
moving at speed many kilometres away, but scientists now believe this to be
what they term an electrophonic effect. 

It is possible that the twisting wake of a fireball might trap a magnetic
field, creating very long radio waves that travel to the ground at the speed
of light. The waves then interact with almost any object to produce a sound
audible to the skywatcher. 

Copyright 2000, BBC

======================================================================

(11) PHYSICAL PROPERTIES OF PHAETHON

>From Alan Harris /DLR, Berlin <Alan.Harris@dlrdot de>

Dear Benny,

   In the light of Neil Bone's interesting comments on the characterstics
of the Geminid meteor stream (CCNET Letters, 11th Oct.), we should
remember that the physical properties of Phaethon, as deduced from
infrared observations, are not what might be expected of an extinct or
dormant comet.

   This was pointed out by Green, Meadows and Davies (1985, MNRAS, 214,
29p-36p) who obtained a value of 0.11 +/- 0.02 for Phaethon's
albedo. Cometary nuclei are expected to be much darker than this
(e.g. albedo of 0.04 for Halley and similar albedos found
for trans-Neptunian objects). Furthermore, the thermal inertia of
Phaethon appears to be more than 6 times that of the lunar surface
(Harris, Davies, Green, 1998, Icarus, 135, 441-450), i.e. characteristic
of bare rock, and NOT of a porous, dusty surface such as one might
imagine an extinct or dormant cometary nucleus having. So Phaethon doesn't
"look" like a dead comet (although to be honest we don't really know what
such a thing should look like...).

   These results seem to be relevant to Neil Bone's remarks:

"...Both these characteristics are, as I understand it, ascribable to
the greater density and physically 'robust' nature of Geminid meteoroids
(2gcm^3) compared with the 'dust-balls' shed by comets (0.2-0.3 gcm^3).
In the case of the Geminids, are we not dealing with rocky fragments -
for which, I agree, an ejection mechanism has to be found - and which
are quite different from those which populate cometary meteor
streams? Surely the presence of a meteor stream is not, in itself, a
reason to suggest that Phaethon was once a comet?"

   So it seems neither the astronomical nor the meteoroid evidence
supports the case for Phaethon having once been a comet. Nevertheless,
it's still a very strange beast in the asteroid zoo...

Alan Harris
DLR, Berlin

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