PLEASE NOTE:
*
CCNet 116/2001 - 8 November 2001
================================
"Our estimate for the chance of a big impact contains some
of the
same uncertainties as previous estimates. But it is clear that we
should
feel somewhat safer than we did before we had the Sloan survey
data."
--Zeljko Ivezic, Princeton University, 7 November 2001
"The Sloan study is a major advance in our understanding of
the
gross asteroid belt structure. Their determination of the Earth
impact
rate for killer asteroids agrees with soon-to-be-published
results based
on data from the Spacewatch Project at the University of
Arizona."
--Robert Jedicke, University of Arizona, 7 November 2001
"The observations are Main-belt asteroids (so far as they
can tell
from one-night stands). So they are estimating the population of
NEAs by taking their estimate of MBAs and multiplying by some
magic
factor (one in a thousand, probably) to estimate the number of
NEAs. This
is complete, embarassing, BLATHER not worthy of notice by anyone
on this
list."
--Alan Harris, Jet Propulsion Laboratory, commenting on the
Princeton University press release, Minor Planet
Mailing List, 7 November 2001
"Donald Yeomans, an asteroid expert at NASA's Jet Propulsion
Laboratory, said the 1-in-5000 figure has been accepted for years
and is
based on a population of Near Earth Asteroids (NEAs)[...] the
Sloan survey
did not study Near Earth Asteroids, but instead looked at objects
primarily in the main asteroid belt. Asteroids that far away
represent no
threat to Earth over the next century and well beyond, Yeomans
said.
They are orbiting the Sun in relatively comfortable
fashion."
--Rob Britt, Space.com, 8 November 2001
(1) FEWER ASTEROIDS IN MAIN BELT, SURVEY SHOWS
Space.com, 8 November 2001
(2) SKY SURVEY LOWERS ESTIMATE OF ASTEROID IMPACT RISK - NOT
Ron Baalke <baalke@jpl.nasa.gov>
(3) SCIENCE GIVES HUMANITY A REPRIEVE
Evening Standard, 7 November 2001
(4) MILITARY SATELLITES BRACE FOR LEONID METEOR SHOWER
Space.com, 7 November 2001
(5) JAW-DROPPING LEONIDS
NASA Science News, 7 November 2001
(6) CANADIAN SCIENTISTS SEEKING HELP IN SEARCH FOR METEOR
Ron Baalke <baalke@zagami.jpl.nasa.gov>
(7) CRATER MAKES AN IMPACT ON THREE SESSIONS AS GSA
Ron Baalke <baalke@jpl.nasa.gov>
(8) GOSH! SPECIES MORE LIKELY TO SURVIVE AFTER MASS EXTINCTION
EVENT THAN
BEFORE
Science Daily, 7 November 2001
(9) PLEISTOCENE MEGA-FAUNA MASS EXTINCTION: YOUNGER DRYAS 'NO
UNIQUE CLIMATE
EVENT'
Andrew Yee <ayee@nova.astro.utoronto.ca]
(10) US HOUSE-SENATE CONFERENCE APPROVES PLUTO MISSION FUNDING
The Planetary Society <tps@planetary.org>
(11) SERVING UP METEORITES ON ICE
Planetary Science Research, 7 November
2001
(12) AL AMARAH STRUCTURE
Giesinger Norbert <norbert.giesinger@siemens.at>
(13) SALUTE TO ACC AND AN APPEAL TO THE SPACE FRONTIER GALA FOLKS
Andy Smith <astrosafe@yahoo.com>
===================
(1) FEWER ASTEROIDS IN MAIN BELT, SURVEY SHOWS
>From Space.com, 8 November 2001
http://www.space.com/scienceastronomy/solarsystem/asteroid_risk_011108.html
By Robert Roy Britt
Senior Science Writer
There may be fewer large asteroids in the solar system than
previously
believed according to a new survey released Wednesday.
Astronomers using data from the Sloan Digital Sky Survey say that
the main
asteroid belt, between Mars and Jupiter, contains about 700,000
space rocks
larger than 1 kilometer (0.62 miles). Previous estimates had put
the count
at around two million.
The survey involved several institutions mapping a quarter of the
sky, so
the new estimate represents an extrapolation to the entire sky.
The survey
data also allowed the astronomers to better gauge the size of
asteroids by
studying their composition. An asteroid's size is estimated in
part by the
amount of light it reflects, which is tied to the surface
composition.
"The Sloan study is a major advance in our understanding of
the gross
asteroid belt structure," said Robert Jedicke, an asteroid
expert at the
University of Arizona.
Millions and millions of smaller rocks are thought to inhabit the
asteroid
belt.
Threat to Earth?
The researchers involved in the study, led by Zeljko Ivezic of
Princeton
University, said their work reduced the odds that an asteroid
larger than 1
kilometer would hit Earth sometime in the next 100 years. They
say the odds
had been reduced from 1-in-1500 over the next century to
1-in-5000.
But Donald Yeomans, an asteroid expert at NASA's Jet Propulsion
Laboratory,
said the 1-in-5000 figure has been accepted for years and is
based on a
population of Near Earth Asteroids (NEAs). Asteroids that are
thought to be
near enough to our planet that gravity could lure them in
sometime soon.
Scientists at NASA and elsewhere work together to find and track
NEAs,
especially those 1 kilometer and larger. Experts say only rocks
that large
are capable of causing global catastrophe and possibly destroying
civilizations. Between 700 and 1200 are thought to exist. Roughly
500 have
been found. All are on courses that pose no threat to Earth.
Asteroids larger than 1 kilometer are suspected of hitting Earth
every
100,000 to 300,000 years, according to widely accepted estimates
based
partly on a handful of terrestrial craters. But Earth tends to
bury or erode
the evidence. So the estimate is based also on craters on the
Moon, which do
not erode quickly but which provide a glimpse into what likely
happens on
Earth.
Smaller asteroids hit Earth more frequently and can wipe out a
city. Objects
the size of a bus or smaller tend to burn up as they zoom through
Earth's
atmosphere, and therefore they pose little or no threat.
At any rate, the Sloan survey did not study Near Earth Asteroids,
but
instead looked at objects primarily in the main asteroid belt.
Asteroids
that far away represent no threat to Earth over the next century
and well
beyond, Yeomans said. They are orbiting the Sun in relatively
comfortable
fashion.
The Sloan results were published in the November issue of the
Astronomical
Journal.
Copyright 2001, Space.com
=================
(2) SKY SURVEY LOWERS ESTIMATE OF ASTEROID IMPACT RISK - NOT
>From Ron Baalke <baalke@jpl.nasa.gov>
http://www.eurekalert.org/pub_releases/2001-11/pu-ssl110701.php
Public release date: 7-Nov-2001
Contact: Steven Schultz
sschultz@princeton.edu
609-258-5729
Princeton University
Sky survey lowers estimate of asteroid impact risk
Princeton, N.J. -- The odds of earth suffering a catastrophic
collision with
an asteroid over the next century are about one in 5,000, which
is less
likely than previously believed, according to research published
this month.
Astronomers using data from the Sloan Digital Sky Survey found
that the
solar system contains about 700,000 asteroids big enough to
destroy
civilization. That figure is about one-third the size of earlier
estimates,
which had put the number at around two million and the odds of
collision at
roughly one in 1,500 over a one hundred-year period.
"Our estimate for the chance of a big impact contains some
of the same
uncertainties as previous estimates, but it is clear that we
should feel
somewhat safer than we did before we had the Sloan survey
data," said lead
researcher Zeljko Ivezic of Princeton University.
The results were published in the November issue of the
Astronomical
Journal.
The new estimate draws on observations of many more asteroids,
particularly
small faint ones, than were available in previous impact risk
estimates,
said Ivezic. The ability to detect faint objects in large numbers
is a
hallmark of the Sloan survey, a multi-institutional collaboration
that is
mapping one-quarter of the sky. While its main purpose is to look
at objects
outside our galaxy, the survey also records images of closer
objects that
cross the view of its telescope, which is located at the Apache
Point
Observatory in New Mexico.
The survey data also allowed the astronomers to gauge the size of
asteroids
with improved accuracy, which required categorizing the objects
by their
composition. Asteroids with a surface of carbon -- looking like
giant lumps
of coal -- are darker than those made of rock. A small rocky
asteroid
therefore looks just as bright as a much larger one made of
carbon.
"You don't know precisely the size of an object you are
looking at unless
you know what type it is," Ivezic said, noting that the
Sloan survey
provides information about the color of objects, which allows
astronomers to
distinguish between carbon and rock.
Based on observations of 10,000 asteroids, the researchers
estimated that
the asteroid belt contains about 700,000 that are bigger than one
kilometer
(six-tenths of a mile) in diameter, which is the minimum size
thought to
pose a catastrophic risk to humans and other species. The
asteroid belt is
the source for a smaller group of asteroids called "near-
earth objects,"
which have broken from the belt and have the potential to collide
with
earth. Although they did not specifically observe near earth
objects, the
researchers believe that their census of main belt asteroids
reveals the
likelihood of collisions with similarly sized near-earth
asteroids.
Ivezic noted that the new impact risk estimate, like most
previous ones,
relies on assumptions about a single event 65 million years ago
when a
10-kilometer asteroid collided with earth and killed the
dinosaurs. The
researchers assumed that such impacts occur on roughly 100
million-year
intervals and used that statistic to calculate the impact odds
for the more
common asteroids of smaller sizes. This calculation required
knowing how
much more common one-kilometer asteroids are than 10-kilometer
ones, which
was hard to measure before the Sloan data was available.
"There is a lot of uncertainty when you have a sample of
only one event,"
Ivezic said, referring to the dinosaur-killing impact. "But
this is the best
information we have."
Previous studies could detect only asteroids five kilometers or
larger, so
astronomers had to extrapolate to estimate the number of smaller
ones, said
Ivezic. The Sloan researchers found that this approach produced
high
estimates. When they could actually observe them, the small
asteroids were
not as plentiful as had been expected from observations of large
ones.
The reason for this reduced number of smaller asteroids is an
open question,
which, if answered, may offer important clues about the history
of the solar
system and the factors that shaped the asteroid belts, said team
member
Serge Tabachnik of Princeton.
Another valuable piece of information for scientists is the
observation that
the rock and carbon asteroids are separated into two bands, said
co-author
Tom Quinn of the University of Washington. The heart of the rocky
asteroid
belt is 260 million miles from the sun, while the other is 300
million miles
from the sun. The sun and earth, by comparison, are 93 million
miles apart.
The astronomers attribute much of the success of the study to
software that
automatically identifies asteroids from among the millions of
images
observed by the Sloan survey. Independent tests by Mario Juric
from the
University of Zagreb, Croatia, have shown that the Sloan software
finds at
least nine of every ten asteroids.
"We have only five minutes to follow the motion of an
asteroid as it passes
in front of the telescope," said Robert Lupton, a Princeton
researcher who
developed the software for automatic detection of asteroids.
"But we have
found that we detect them very efficiently and reliably."
Lupton said the
team benefited greatly from software for finding the positions
and relative
movements of objects, developed by Jeff Pier, Jeff Munn, Robert
Hindsley and
Greg Hennessy of the U.S. Naval Observatory.
"The Sloan study is a major advance in our understanding of
the gross
asteroid belt structure," said Robert Jedicke, an asteroid
expert at the
University of Arizona. "Their determination of the Earth
impact rate for
killer asteroids agrees with soon-to-be-published results based
on data from
the Spacewatch Project at the University of Arizona." The
Arizona team based
its risk estimate on a study of near-earth objects, rather than
main belt
asteroids.
###
The Sloan Digital Sky Survey (www.sdss.org)
is a joint project of the
University of Chicago, Fermilab, the Institute for Advanced
Study, the Japan
Participation Group, the Johns Hopkins University, the
Max-Planck-Institute
for Astronomy, the Max-Planck-Institute for Astrophysics, New
Mexico State
University, Princeton University, the United States Naval
Observatory and
the University of Washington.
Funding for the survey has been provided by the Alfred E. Sloan
Foundation,
the participating institutions, the National Aeronautics and
Space
Administration, The National Science Foundation, the U.S.
Department of
Energy, the Japanese Monbukagakusho and the Max Planck Society.
===================
(3) SCIENCE GIVES HUMANITY A REPRIEVE
>From Evening Standard, 7 November 2001
http://www.thisislondon.com/dynamic/news/story.html?in_review_id=451498&in_review_text_id=401723
Human beings have only a small chance of being wiped out by an
asteroid
impact over the next century, according to scientists.
The odds of one in 5,000 they give of such an event happening are
more
comforting than a previous estimate of one in 1,500 over a
100-year period.
Astronomers analysing data from a new study called the Sloan
Digital Sky
Survey have calculated that the Solar System contains about
700,000
asteroids big enough to destroy civilisation.
The figure is about a third of the size of previous estimates,
which had put
the number at around two million.
Chief scientist Zeljko Ivezic, of Princeton University, New
Jersey, USA,
said: "Our estimate for the chance of a big impact contains
some of the same
uncertainties as previous estimates.
"But it is clear that we should feel somewhat safer than we
did before we
had the Sloan survey data."
Copyright 2001, Evening Standard
==============
(4) MILITARY SATELLITES BRACE FOR LEONID METEOR SHOWER
>From Space.com, 7 November 2001
http://www.space.com/businesstechnology/technology/leonids_satellites_011107-1.html
By Jim Banke
Senior Producer, Cape Canveral Bureau
CAPE CANAVERAL, Fla. -- Satellite operators will keep a close eye
on their
Earth-orbiting spacecraft during the upcoming Leonid meteor
shower, and
though the risk of damage from a stray speck of dust is greater
than normal,
officials are confident there will be no natural disasters in
space.
Nevertheless, if a Leonid meteoroid hits a satellite, the small
grain can
destroy an imaging mirror or plow through fragile parts such as
an
electricity-generating solar panel, possibly creating electrical
shorts that
can disable the craft. Just the momentum imparted by an impact
can throw a
satellite off course.
Especially sensitive at this time -- but not necessarily
vulnerable -- are
the nation's reconnaissance, communications, navigation and
weather
forecasting satellites, which are playing a key role in the
United States'
efforts to combat terrorism in Afghanistan, and around the globe.
Not to worry, officials say.
"Satellites are designed with information about past storms
and other things
that can happen in space," said Capt. Adriane Craig, a
spokesperson for the
U.S. Air Force Space Command at Peterson Air Force Base near
Colorado
Springs, Colo.
"Our satellites are robust and in the event that there is a
problem we have
backup systems and contingency plans to help get them back
online."
Air Force controllers at Peterson are responsible for monitoring
the various
constellations of military satellite systems around the clock,
Craig said,
but she wouldn't say exactly what additional measures -- if any
-- are being
taken to minimize the threat from the Leonids.
"For the Leonids we have models that help us predict when
the storm will
peak, so certainly (the satellite operators) can be more
attentive during
that time, but we monitor the spacecraft pretty vigilantly every
day of the
year," she said, politely refusing to elaborate. "I
will not reveal anything
operationally about any actions we might or might not take."
The story is the same at the National Reconnaissance Office
(NRO), which is
responsible for operating the many clandestine spy satellites
responsible
for so much of the nation's space-based intelligence gathering
efforts.
"We're working closely with the Air Force to fully
understand the
implications of the Leonid storm, and we'll take precautions that
we feel
are appropriate," said Art Haubold, a spokesman for the
National
Reconnaissance Office. "However, we don't discuss
operational details of our
satellites."
It's possible that in some cases a satellite may be turned off as
the best
defense against being struck by a Leonid meteoroid. However,
industry
observers and others agree that military and NRO spacecraft are
constructed
with extra shielding and back up systems inside the spacecraft
itself,
allowing continuing operation no matter what.
"Military satellites are much more hardened and much more
capable of
surviving such things than normal satellites," said Bill
Cooke, a meteor
forecaster at NASA's Marshall Space Flight Center in Huntsville,
Ala.
So to, Cooke said, is the International Space Station, where the
current
Expedition Three crew of Frank Culbertson, Vladimir Dezhurov and
Mikhail
Turin are wrapping up a four-month stay in space. Shuttle
Endeavour is to be
launched Nov. 29 -- long after the Leonid's peak -- to bring up a
new crew
and then return to Earth on Dec. 10.
"The space station has armor to protect it against stuff as
much as an inch
across," Cooke said. "We're not expecting anything that
big from this year's
Leonids."
Remnants from the icy comet Tempel-Tuttle, the Leonid meteor
shower will
result when planet Earth sweeps through the comet's trail of
debris next
week and the tiny particles encounter our atmosphere and burn up,
sparking
what are commonly called shooting stars.
Earth will enter the heavier parts of the stream at about 11 p.m.
EST on
Nov. 17 (0400 GMT Nov. 18). Activity will peak around 5 a.m. EST
Nov. 18
(1000 GMT), when as many as 13 meteors per minute could be
visible, likely
for a stretch of time that lasts less than one hour.
No larger than a grain of sand, the Leonid meteroids tend to
vaporize at
about 60 miles (100 kilometers) above the surface. Satellites,
however, are
orbiting the planet much higher and so could be hit by the bits
before they
burned up.
Satellites that orbit between 200 and 600 miles (325 and 965
kilometers)
above Earth will face meteor rates roughly the same as what is
expected to
be seen from the ground, Cooke said.
However, high-flying geostationary satellites, which sit 22,300
miles
(35,900 kilometers) above the planet will be closer to the
densest part of
the debris stream. Moreover, geostationary satellites in the
Western
Hemisphere would be at the greatest risk, Cooke said.
Because Tempel-Tuttle orbits the Sun in the opposite direction
compared to
Earth -- a backward motion called retrograde -- its debris would
hit a
satellite with much greater velocity than other meteors created
by the
debris from other comets.
"It's like two cars hitting head-on," Cooke said,
adding that the
penetration power is 16 times that of a normal meteor.
The greatest danger, Cooke says, is the generation of a plasma
cloud -- a
byproduct of high-speed impacts that could cause an electrical
short
circuit.
When a meteor as fast as a Leonid strikes something, it
vaporizes, creating
a cloud of plasma, or electrically charged particles. An
electrical current
can then flow from one part of the craft, through the plasma
cloud, and then
destroy an instrument on another part of the craft.
Few such instances have been documented.
In 1993, during the August Perseid meteor shower, a meteor hit an
Olympus
communications satellite. The impact formed a plasma cloud, and
the craft's
attitude control system was zapped. By the time operators could
stabilize
it, they had depleted all of its attitude-control propellant and
the
satellite was lost.
Copyright 2001, Space.com
===============
(5) JAW-DROPPING LEONIDS
>From NASA Science News, 7 November 2001
http://science.nasa.gov/headlines/y2001/ast08nov_1.htm?list20392
On Sunday morning, Nov. 18, 2001, sky watchers somewhere will see
a dazzling
storm of Leonid meteors. Read this story and find out how
you can be one of
them.
November 8, 2001: I'll never forget the night of November 17,
1998. It was
cold outside my mountain home at 9000 ft. The skies were crystal
clear. And
it was very dark.
That is, except for the fireballs.
I was sky watching with a friend, both of us experienced
astronomers.
Nevertheless, we stared upwards like novices, slack-jawed, as if
we had
never seen the sky before.
We were witnessing the annual Leonid meteor shower. But these
were no
ordinary Leonids. They were bright, vivid, shadow-casting
fireballs. Every
five minutes or so we saw one as bright as Venus, and a fair
number would
have outshined a Full Moon. Some of the most startling left
behind glowing
trails of debris that lingered in the sky, twisting and turning
as they were
sheared by high-altitude winds.
It was unforgettable.
In years since I've heard sky watchers refer to that event as the
"1998
Leonid fireball storm." But it wasn't really a storm at all.
Meteor rates
that night never exceeded a few hundred shooting stars per hour.
"We define
a meteor storm to be times when observers can see 1000 or more
per hour,"
says Bill Cooke from the NASA Marshall Space Flight Center.
"The Leonids of
'98 -- as spectacular as they were -- were not a full-fledged
storm."
But the Leonids of 2001 will be.
Cooke and other experts agree that when the Leonids return later
this month
sky watchers in some parts of the world will see a display even
better than
the one in 1998. Indeed, says Cooke, "what's coming on Nov.
18th could be
the biggest event since 1966 [when North Americans enjoyed a
Leonid storm
numbering 100,000 shooting stars per hour]."
Observers in North America, Hawaii, Australia, and Asian
countries along the
Pacific Rim will be favored for the best views of the 2001
Leonids. Meteor
rates in those places could climb as high as 8000 per hour -- not
quite as
intense as the 1966 storm, but more than enough to make a sky
watcher's jaw
drop.
Leonid Forecasts for Nov. 18, 2001
North America
9:00 - 11:00 UT
4:00 - 6:00 a.m. in New York
1:00 - 3:00 a.m. in Los Angeles
800 - 4000 per hour
California, Hawaii, Samoa
11:00 - 15:00 UT
3:00 - 7:00 a.m. in Los Angeles
1:00 - 5:00 a.m. in Hawaii
100 - 1000 per hour
Australia, Indonesia, Japan, east Asia
17:00 - 19:30 UT
0400 - 06:30 a.m. in Sydney
0200 - 04:30 a.m. in Tokyo
800 - 8000 per hour
Table notes: UT is Universal Time, also known as Greenwich Mean
Time or GMT.
ZHR is the Zenithal Hourly Rate -- that is, the number of meteors
a observer
with dark skies would see if the constellation Leo were directly
overhead.
The range in predicted ZHRs reflects differences among the models
of various
forecasters. [more information]
Leonid meteor storms happen when Earth passes through clouds of
dusty debris
shed by comet 55P/Tempel-Tuttle when it comes close to the Sun
every 33
years. This year our planet is heading for close encounters with
four such
clouds. They bubbled off Tempel-Tuttle in 1699, 1766, 1799 and
1866.
"Each encounter with a dust cloud will produce an outburst
of Leonids over
some part of our planet," explains Cooke. "For example,
the best place to
view the 1799 meteoroids is Hawaii. That's where I'll be!"
The 1766 cloud
will produce a flurry of Leonids over North America, while the
1699 and 1866
clouds will rain meteors over Australia and east Asia.
"These clouds are long and narrow like a comet's tail,"
says Cooke. "The
younger ones are only 10 or so Earth-diameters wide." Our
chances of hitting
something so narrow and filamentary are slim. Indeed, most years
in November
we miss them altogether. Earth glides between the clouds where
there is only
a sprinkling of meteoroids. At such times Leonid rates remain
low: only 10
or 15 meteors per hour.
"In 1998 we passed through material shed by the comet in
1333," says Cooke.
"That filament was old and somewhat spread out," so
rates never climbed to
storm levels. It was nevertheless spectacular because "the
smallest bits of
dust inside that cloud had been blown away long ago by solar
radiation
pressure. Only the largest meteoroids remained -- hence the
fireballs."
"In 2001 we're running into relatively young clouds, richer
in small
meteoroids," added Cooke. "Observers from '98 who
remember mostly fireballs
will be dazzled this year instead by a greater number of ordinary
meteors."
Although certain parts of the world are favored for intense
activity this
year, Cooke encourages people everywhere to watch the sky on Nov.
18th. "The
Leonids might surprise us," he says. Predicted outbursts
might fizzle, and
activity could surge at unexpected times.
Veteran meteor watchers are wary of Leonid predictions because
the science
of forecasting Leonid meteor storms is still young. The basic
techniques
were pioneered only three years ago by astronomers David Asher
(Armagh
Observatory) and Rob McNaught (Australian National University).
They
correctly predicted a brief meteor storm over the Middle East and
Europe in
1999. Then, in 2000, they and others used similar methods to
forecast the
times of three more Leonid flurries. It's a promising track
record, but by
no means well-established.
If you're determined to spot some Leonids this year, here is the
best
strategy: Dress warmly and travel (if necessary) to a dark-sky
site away
from urban light pollution. Be prepared to watch the sky between
midnight
and sunrise on Sunday morning, Nov. 18th. Meteor rates will
probably be low
near midnight -- although that is a good time to see beautiful
Earthgrazing
Leonids -- then climb to 10 or 20 per hour by dawn. If you're
lucky you
might witness a storm-level outburst and count thousands of
shooting stars.
With the Leonids there are no guarantees.
No matter, the coming shower will surely send some sky watchers
home with
life-long memories. "I'll never forget the night of Nov
18th, 2001," they
might recall years from now -- just as I remember the Leonids of
1998.
Others, perhaps, will gain little more than a quiet night under
the stars.
One thing is certain: if you stay indoors you won't see anything!
===============
(6) CANADIAN SCIENTISTS SEEKING HELP IN SEARCH FOR METEOR
>From Ron Baalke <baalke@zagami.jpl.nasa.gov>
http://www.canada.com/calgary/news/story.asp?id={5DDF144D-650D-4470-80EA-9E429C036EC5}
Scientists seeking help in search for meteor canada.com
November 7, 2001
CALGARY -- Researchers are hoping someone has a photograph or
video of the
biggest meteor to fall in Alberta in 40 years so they can tell
where it
landed.
Alan Hildebrand, a planetary scientist at the University of
Calgary, says
the meteor was an asteroidal fragment that weighed five to 10
tonnes, about
1.5 meters in diameter.
Hildebrand says it was travelling at roughly 20 kilometres per
second and
this was probably the biggest rock to fall on Alberta since
1960.''
The flaming rock was seen streaking north across the Alberta sky
near the
British Columbia boundary on October 14th at around 2:20 a.m.
It exploded over the northern part of Banff National Park with a
deafening
boom that could be heard 150 kilometers away.
Eyewitnesses reported seeing hundreds of pieces of the rock
falling to the
ground, however, freshly fallen snow may delay the hunt for
particles until
next spring.
=================
(7) CRATER MAKES AN IMPACT ON THREE SESSIONS AS GSA
>From Ron Baalke <baalke@jpl.nasa.gov>
http://www.usgs.gov/public/press/public_affairs/press_releases/pr1521m.html
----------------------------------------------------------------------------
News Release
Address
U.S. Department of the
Interior
953 National Center
U.S. Geological
Survey
Reston, VA 20192
Release
Contact
Phone Fax
November 6,
2001 Diane
Noserale 703-648-4333
703-648-6859
----------------------------------------------------------------------------
Crater Makes an Impact on Three Sessions at GSA
Note to Editors: Interviews with the scientists during the
Geological
Society of America (GSA) Annual Meeting can be arranged by
contacting
Carolyn Bell (USGS) or Ann Cairns (GSA) in the GSA newsroom in
Boston at
617-954-3214.
What happens when a rock from space that's more than a mile wide
slams into
the Earth at supersonic speed? Scientists from the U.S.
Geological Survey
(USGS) and its partners are learning as they analyze evidence
they are
recovering from cores drilled during the past two summers into
the
Chesapeake Bay impact crater and surrounding structures. USGS
scientists
David Powars, C. Wylie Poag, and J. Wright Horton, Jr. will
present new
evidence obtained from cores and seismic surveys, on the
devastating effects
this event had on the Earth 35 million years ago, during three
separate
sessions at the Annual Meeting of the Geological Society of
America,
scheduled for Nov. 4-8 in Boston, Massachusetts.
It's bigger and deeper than we imagined: "This comet or
asteroid shot
through the Earth's atmosphere, leaving a vacuum in its wake.
Then it hit,
splashing through several hundred feet of ocean and slicing
through several
thousand feet of coastal plain sediments," says Powars.
"It fractured the
crystalline bedrock below to at least a depth of seven miles and
a width of
85 miles. Billions of tons of ocean water were vaporized and
millions of
tons of debris were ejected into the atmosphere within minutes.
Marine life
was decimated, and a train of giant waves of seawater inundated
the land,"
explains Powers, whose talk "Structure and Composition of
the Southwestern
Margin of the Buried Chesapeake Bay Impact Structure,
Virginia" is scheduled
for 4:45 pm Tues, Nov. 6, Hynes Convention Center Room 202.
What's written in stone: USGS scientists are looking for clues
left in the
bedrock from this extraordinary event in the deep past, to deal
with an
ordinary modern-day issue: finding ground water suitable to
support a
rapidly-developing region. Studies are underway to understand the
impact
structure and its influence on ground water.
"We are examining the composition, age, and structure of
crystalline
basement rocks beneath the Coastal Plain sediments. We are
beginning to
learn more about these rocks and how they were affected by the
impact
event," Horton explains.
"Crystalline rocks hidden under the blanket of Coastal Plain
sediments make
up one of the most poorly understood areas of geology in the
U.S., and
drilling in the impact structure has provided rare samples from
as deep as
2083 feet." "Crystalline Rocks from the First Corehole
to Basement in the
Chesapeake Bay Impact Structure, Hampton, Virginia" is
scheduled for 2:45 pm
Thurs., Nov. 8, Hynes Convention Center Room 200.
Not a creature was stirring: USGS scientists have recently
identified a zone
of silt above the post-impact fallout that is devoid of signs of
indigenous
life. Wylie Poag points out that the heat from this impact must
have
instantly incinerated every living thing within hundreds of
miles. Poag will
review evidence -- such as fractures and deformation features in
crystals,
melted rock, and tiny glass spheres -- that indicate shock
pressures at
ground zero that could only have come from an impact. "From
Shocked Basement
to Fallout Spherules: The Coring Record at the Chesapeake Bay
Crater" is
scheduled for 4:15 pm Thurs, Nov. 8, Hynes Convention Center Room
304.
The USGS serves the nation by providing reliable scientific
information to:
describe and understand the Earth; minimize loss of life and
property from
natural disasters; manage water, biological, energy, and mineral
resources;
and enhance and protect our quality of life.
*** USGS ***
=================
(8) GOSH! SPECIES MORE LIKELY TO SURVIVE AFTER MASS EXTINCTION
EVENT THAN
BEFORE
>From Science Daily, 7 November 2001
http://www.sciencedaily.com/releases/2001/11/011107073104.htm
University Of Cincinnati Geologist Finds Survival Benefit To
Evolving After
Mass Extinctions
Cincinnati - An evolutionary group has a significantly better
chance of
surviving for a long time in the geologic record if it first
appears right
after a mass extinction.
University of Cincinnati geologist Arnold Miller will present his
findings
Tuesday morning Nov. 6 during the annual meeting of the
Geological Society
of America in Boston.
Professor Miller used a database of marine fossil genera compiled
by J. John
Sepkoski to examine longevity trends throughout the Phanerozoic
(the last
540 million years). In four separate cases, he found that genera
first
appearing following mass extinctions survived for longer periods
of time, on
average, than those that first appeared at other times.
"There was already a sense that organisms originating in the
wakes of mass
extinctions were generalists with respect to their geographic and
environmental distributions," said Miller. "My analysis
indicates that these
characteristics promoted evolutionary longevity."
Miller said that the trend is apparent no matter what the
ultimate cause was
of each mass extinction. Genera that were more widespread, might
have fared
better over the long run because of a kind of "safety in
geography." If a
catastrophe decimated the individuals living in one region, then
a genus
could still survive if individuals belonging to the genus also
lived in
other regions.
To conduct his analysis, Miller divided the Phanerozoic into 156
"bins" or
substages. Then, he looked at the average longevity of genera
originating in
each bin. Significant peaks in mean longevities occurred in the
substages
following major mass extinctions in Late Permian, Late Triassic,
and Late
Cretaceous-three of the "big five" extinctions of the
Phanerozoic-and
following a lesser, but still significant extinction at the end
of the
Jurassic.
"These are very sharp peaks," noted Miller, who
followed up his first
analysis with a number of statistical techniques to weed out
artifacts in
the data set. "I was trying and trying to kill the pattern,
but it wouldn't
go away."
One enigma in the analysis is that the pattern does not extend
back into the
Paleozoic, the earliest of the three eras that comprise the
Phanerozoic.
Although there were fairly high extinction rates during parts of
the
Cambrian, Ordovician and Devonian, Miller's analysis showed no
clear
relationship between extinction events and longevity in any of
those
periods. "To see nothing is quite something," he said,
summing up that
intriguing finding.
It is possible that, after the Paleozoic, there was a major
change in the
dynamics of evolution, but Miller noted that any real explanation
for the
difference between the Paleozoic and post-Paleozoic remains to be
determined.
Miller is currently working with a team of geologists worldwide
to build an
online database that depicts the occurrences of marine genera
throughout the
Phanerozoic, and which will incorporate data on the geography and
paleoenvironment of each occurrence. In the future, he hopes to
use these
data to assess directly whether the longer-lived genera really
were those
with wider geographic and environmental distributions. "We
really haven't
looked definitively at the characteristics of the post-extinction
players,
but with the databases we're building, we'll be able to."
Miller's work is supported by NASA's Program in Exobiology and
NSF's Program
in Biocomplexity.
=================
(9) PLEISTOCENE MEGA-FAUNA MASS EXTINCTION: YOUNGER DRYAS 'NO
UNIQUE CLIMATE
EVENT'
>From Andrew Yee <ayee@nova.astro.utoronto.ca]
Geological Society of America
Boulder, Colorado
Contact:
Ann Cairns, Director-Communications and Marketing
acairns@geosociety.org,
303-357-1056
FOR IMMEDIATE RELEASE: November 7, 2001
GSA Release No. 01-55
Why the Big Animals Went Down in the Pleistocene -- Was it Just
the Climate?
Written by Kara LeBeau, GSA Staff Writer
There wasn't anything special about the climate changes that
ended the
Pleistocene. They were similar to previous climate changes as
recorded in
deep sea cores. So what tipped the scale and caused the
extinction?
Russell Graham, who has been working on climate models for
Pleistocene
extinction for almost 30 years, looked for triggers in a
threshold effect
that did not require a unique climate change. Graham, Chief
Curator at the
Denver Museum of Nature and Science, will present his research on
Wednesday, November 7, at the Geological Society of America's
annual meeting
in Boston, Massachusetts.
"The end Pleistocene climate change, especially the Younger
Dryas [a sudden
cold period], was a trigger that tipped the balance," he
explained. "Also,
the climate model needed to answer the question of why big
animals --
mammoths, mastodons, ground sloths, etc., were the primary ones
to go
extinct and not the small ones. The answer to this question is
the
relationship between geographic range and body size. The larger
an animal,
the more real estate or geographic range it needs to support
viable
populations, especially in harsh environments like those of the
Pleistocene
... . Therefore, if the geographic range of animals decreased
through time
then their probability of extinction would increase with
time."
Graham successfully tested his hypothesis by using a computer
database of
fossil ice age mammal sites linked with a geographic information
system to
map changes in the distribution of species throughout time.
"This is one of the first models that does not require a
unique climate
change at the end of the Pleistocene. To my knowledge it is one
of the first
to look at geographic range changes of a large number of mammal
species as
the primary driving factor of the extinction."
CONTACT INFORMATION
During the GSA Annual Meeting, November 4-8, contact Ann Cairns
or Christa
Stratton at the GSA Newsroom in the Hynes Convention Center,
Boston,
Massachusetts, for assistance and to arrange for interviews:
(617) 954-3214.
The abstract for this presentation is available at:
http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_17728.htm
Post-meeting contact information:
Russell Graham, Chief Curator
Denver Museum of Nature and Science
2001 Colorado Blvd, Denver, CO 80205
Phone: (303) 370 6073
E-mail: rgraham@dmns.org
Ann Cairns
Director of Communications
Geological Society of America
Phone: 303-357-1056
Fax: 303-357-1074
E-mail: acairns@geosociety.org
==============
(10) US HOUSE-SENATE CONFERENCE APPROVES PLUTO MISSION FUNDING
>From The Planetary Society <tps@planetary.org>
STATEMENT
The Planetary Society
65 N. Catalina Avenue, Pasadena, CA 91106-2301 (626) 793-5100 Fax
(626)
793-5528
E-mail: tps@planetary.org
Web: http://planetary.org
For Immediate Release: November 7, 2001
Contact: Linda Wong
Victory! House-Senate Conference Approves Pluto Mission Funding
The U.S. House and Senate conference committee acting on the
fiscal year
2002 NASA appropriations have approved $30 million funding for
development
of the Pluto-Kuiper Belt mission, despite opposition by the Bush
Administration. They specifically directed that "funds
provided should be
used to initiate appropriate spacecraft and science instrument
development
as well as launch vehicle procurement," and that NASA
proceed with selection
of a team to develop the mission.
"This is a victory for public interest," said Louis
Friedman, Executive
Director of The Planetary Society. "The people let Congress
know that they
want NASA to explore Pluto -- the only remaining unexplored
planet in our
solar system -- and Congress responded."
The Society has been leading a grass-roots effort to convince
Congress to
restore the mission to the NASA budget after the Bush
Administration
proposed eliminating it.
"The strong support for space exploration in the Congress is
very welcome,
especially at a time when there are so many other budget
pressures,"
Friedman added. He praised the House and Senate conferees noting
that they
also restored full funding to the Mars program which had been
threatened
with budget cuts.
If Congress had not restored the funding, the opportunity for
reaching the
last unvisited planet in our solar system would have been lost
for a
generation. Additionally, the chance of seeing its atmosphere
before it
froze and condensed would have been lost for more than a century.
The funding, and launch vehicle constraints, probably mean that
the mission
to Pluto cannot launch until 2006 -- two years later than had
been hoped.
2006 is the last launch opportunity for more than a decade to
utilize a
Jupiter gravity assist -- where the spacecraft would get a boost
from
Jupiter -- to reach Pluto. Mission times, depending on the launch
vehicle
selected, will be from 10-12 years.
The Administration is now faced with the choice of putting Pluto
in its
proposed fiscal year 2003 budget, or risking another fight with
Congress
next year. The Pluto mission was placed by Congress in the Outer
Planets
line item, which also includes a Europa orbiter mission. The
Europa mission
would be launched later than a Pluto-Kuiper Belt mission, but
arrive earlier
at its destination.
-o0o-
THE PLANETARY SOCIETY:
Carl Sagan, Bruce Murray and Louis Friedman founded The Planetary
Society in
1980 to advance the exploration of the solar system and to
continue the
search for extraterrestrial life. With 100,000 members in over
140
countries, the Society is the largest space interest group in the
world.
CONTACT INFORMATION:
For more information about The Planetary Society, contact Linda
Wong at
(626) 793-5100 ext 236 or by e-mail at linda.wong@planetary.org.
The Planetary Society
65 N. Catalina Ave.
Pasadena, CA 91106-2301
Tel: (626) 793-5100
Fax: (626) 793-5528
E-Mail: tps@planetary.org
==================
(11) SERVING UP METEORITES ON ICE
>From Planetary Science Research, 7 November 2001
http://www.psrd.hawaii.edu/Nov01/metsOnIce.html
--- Antarctic meteorites provide a continuous and readily
available supply
of extraterrestrial materials, stimulating new research and ideas
in
cosmochemistry, planetary geology, astronomy, and astrobiology.
Written by Linda M.V. Martel
Hawai'i Institute of Geophysics and Planetology
Annual collections of meteorites from Antarctica are a steady
source of new
non-microscopic extraterrestrial material including lunar and
Martian
samples and rare and unusual flotsam from asteroids. This article
summarizes
research on new kinds of Antarctic meteorites that is not simply
changing
how meteorites are classified but causing a revolution in our
knowledge of
the materials and processes in the solar nebula, our solar
system, and the
formation of asteroids, planets, and ultimately our world. When
the
2001-2002 Antarctic Search for Meteorites (ANSMET) field party
begins
scouting for meteorites on the ice this season, we will be
continuing a
25-year tradition of exploration along the Transantarctic
Mountains. As a
new ANSMET meteorite hunter, I will report to PSRD on this
season's search
and recovery of specimens and how studies of Antarctic meteorites
are
unraveling the secrets of solar system formation.
Finding Rocks That Fall From Outer Space
The U. S. Antarctic Search for Meteorites (ANSMET) program is a
collaborative effort of the National Science Foundation (NSF),
NASA, and the
Smithsonian Institution. Field collection is supported currently
by a grant
from the NSF Office of Polar Programs to Principal Investigator
Dr. Ralph
Harvey at Case Western Reserve University in Cleveland, Ohio.
NASA and the
Smithsonian Institution provide for the classification, curation,
and
distribution of Antarctic meteorites. All three agencies sponsor
research on
the specimens which remain the property of the National Science
Foundation.
The Meteorite Working Group (MWG) reviews requests for samples by
scientists
of all countries. The MWG is a peer-review committee that meets
twice a year
to guide the collection, curation, allocation, and distribution
of the U. S.
collection of Antarctic meteorites.
The National Institute for Polar Research (NIPR) in Tokyo manages
their own
expeditions to Antarctica and oversees the curation, allocation,
and
distribution of Japanese collections of Antarctic meteorites. The
Committee
on Antarctic Meteorites, which also meets approximately twice a
year,
reviews all requests for meteorite samples. The samples are the
property of
the NIPR, and allocations are generally only made for a period of
1 to 2
years.
European expeditions and collection programs in Antarctica
include the
Italian (PNRA) and German GANOVEX programs. European specimens
currently
curated at the Open University, UK are available for study and
can be
requested through the Department of Mineralogy of the Natural
History Museum
in London.
These international collection programs require nothing less than
strategic
trips to the ice by sturdy, trained individuals working together
in a
well-coordinated way to survive and succeed in this extraordinary
environment. What motivates us to venture to a place that was
only a
hypothesized landmass until it was actually sighted in 1820-21?
The thrill
of living in an extreme, remote environment (likened by some to a
space
outpost) with a rich history of heroic exploration, for the
golden chance of
finding pieces of rock from space that tell stories of creation.
From the
beginning, the Antarctic collection programs have aimed to
recover large
enough numbers of meteorites each season so that something
unusual might be
served up, possibly one day a sedimentary rock from Mars showing
evidence of
the planet's watery history.
Tents at Meteorite Hills during the 2000-2001 ANSMET field
season. This
photo was taken from the helicopter while two of the planetary
geologists,
Ben Bussey and Ralph Harvey, began a six-day reconnaissance trip
to ice
fields near Bates Nunatak.
Meteorites Found on the Blue Ice
Since 1976, ANSMET has recovered more than 10,000 specimens from
meteorite
stranding surfaces along the Transantarctic mountains. The total
number of
Antarctic meteorites is closer to 30,000 when you include
Japanese
collections (beginning in 1969) and European collections. This
large number
is uncorrected for pairing--when laboratory examinations show
that two or
more specimens are actually broken pieces of the same rock.
Antarctica (the
highest, driest, coldest, windiest, and emptiest place on Earth)
has proven
to be an exceptionally good hunting ground because meteorites
that have been
falling on the surface through the millennia become buried in the
ice moving
slowly seaward. Where mountains or subsurface obstructions block
the forward
movement of the ice, the old, deep ice, laden with meteorites, is
pushed up
to the surface against the barrier. Strong katabatic winds (winds
blowing
down the slopes) clear the surface of loose ice and snow and aid
sublimation
and mechanical erosion which expose the meteorites on the blue
ice. These
concentrations of meteorites, called stranding surfaces, are not
permanent
but appear and disappear as the ice cap changes.
The Antarctic Meteorite Location and Mapping Project (AMLAMP)
maintains
databases of meteorite locations for each ice field searched by
ANSMET; see
the map below. The Allan Hills-David Glacier Region includes
samples from
Allan Hills, Beckett Nunatak, David Glacier Icefields, Elephant
Moraine,
MacKay Glacier Icefields, Outpost Nunataks, and Reckling Moraine.
The
Darwin-Byrd Glacier Region includes Bates Nunatak, Derrick Peak,
Lonewolf
Nunataks, and Meteorite Hills. The Beardmore Region includes
Bowden Neve,
Dominion Range, Geologists Range, Grosvenor Mountains, Lewis
Cliff,
MacAlpine Hills, Miller Range, and Queen Alexandra Range. The
Wisconsin
Range-Scott Glacier Region includes Gardner Ridge, Graves
Nunataks, Klein
Glacier, Mt. Howe, Mt. Prestrud, Scott Glacier Icefield,
Wisconsin Range,
and Mt Wisting. The Thiel Mountains-Patuxent Region includes
Lapaz Icefield,
Patuxent Range, Pecora Escarpment, Stewart Hills, and Thiel
Mountains.
A complete set of maps, meteorite listings, and explanations are
available
from AMLAMP.
Samples are identified by location (using a three-letter
abbreviation), year
of collection, and unique sample number. For example, the Allan
Hills
location is abbreviated as ALH, Elephant Moraine is EET, Queen
Alexandra
Range is QUE, and Meteorite Hills is MET. Meteorite ALH 81005 was
recovered
in Allan Hills during the 1981-1982 ANSMET field season and was
the fifth
rock analyzed in the lab. It was a significant find because it
turned out to
be a piece of the Moon. The next paragraphs summarize some of the
extraordinary discoveries enabled by ANSMET.
A Suite from the Moon
Scientists have identified 21 meteorites from the Moon. About
half are from
Antarctica and half from hot desert regions. They recognized the
first one,
ALH 81005, in 1982 on the basis of chemical, mineralogical, and
isotopic
compositions. These rocks provide lunar scientists with samples
from places
far from the U. S. Apollo and Russian Luna landing sites,
allowing a much
better understanding of the composition of the lunar crust. More
importantly, the mere fact that impacts could blast rocks off the
Moon
without melting them, gave some credence to the idea that we
might also have
meteorites from Mars. See Randy Korotev's web site at Washington
University
in St. Louis for more information about meteorites from the Moon.
First Martians
The idea that bits of Mars have fallen to Earth was hotly debated
from the
late 1970s to the mid-1980s. The evidence centered around the
relatively
young ages of a group of rocks called the SNC meteorites. They
were a mere
1.3 billion years old, some even younger. Since the Moon's
volcanic engine
stopped more than 2 billion years ago, the argument went, these
meteorites
must come from a much large body. The logical choice was Mars.
The evidence
was circumstantial.
All that changed when scientists measured the gases trapped in
melted
pockets inside EET 79001, a SNC meteorite found at Elephant
Moraine. The
abundances of the gases and the isotopic compositions of them
were dead
ringers for the atmosphere of Mars, as measured by the Viking
landers in
1976. The results stopped all arguments about where the SNC
meteorites came
from--they are our first Martians. There are now 19 Martian
meteorites, six
of which come from Antarctica and seven from hot deserts.
Diamond-studded Rocks
Ureilites may be the most mysterious of all the meteorites. They
were named
for Novo Urei, a small rock that fell in Russia in 1886. Until
people
started collecting meteorites in hot and cold deserts, only six
ureilites
were known. All contained small grains of diamond (a
high-pressure form of
carbon), along with graphite (low-pressure carbon). This was a
startling
discovery because diamonds form at high pressure. Many scientists
proposed
that the diamonds formed deep inside a large body. But as we
understood the
effects of large impacts, it became clear that the diamonds were
the
products of high-pressure shock waves caused by a large impact
event on the
ureilite body. The key question became the source of the diamond.
Was it
originally present in the rocks as graphite that crystallized
along with the
silicate minerals, and was then converted to diamond by shock? Or
was the
diamond forcibly injected into the rocks by an impact event?
During the past 15 years or so, the number of ureilites has
increased
dramatically from only six to 110. Some of the new ones are not
severely
damaged by shock and preserve the original state of the rock and
its carbon
minerals. Examination showed that they contain long lath-shaped
crystals of
graphite intergrown with the silicate minerals. The intergrowth
clearly
indicates that the carbon was not mixed in by a shock event. The
original
six ureilites fell into distinct groups on the basis of the
amount of FeO
(iron oxide) in their olivine and pyroxene. This suggested that
the rocks
within a group were related to each other, but unrelated to the
other
groups. Analyses of the new samples indicate something different,
that there
is a complete gradation in the amount of FeO, not separate
groups. The
relationships among the ureilites are not so simple and
researchers are
continuing to try to understand the geologic processes on the
ureilite
parent body.
Leftovers From the Birth of the Solar System
Chondrites are meteorites that contain rounded objects (called
chondrules)
that cooled very rapidly from a molten state. For a long time
most
scientists thought chondrules formed directly in the solar
nebula--the cloud
of gas and dust surrounding the primitive Sun. However, chemical
and
mineralogical properties of chondrules and experiments designed
to reproduce
the mineral intergrowths in chondrules showed that they could not
possibly
have condensed from a gas. The condensation idea gave way in the
1980s to
the hypothesis that chondrules formed from small aggregations of
dust (like
those fluffy dust balls that accumulate under your bed) that were
melted by
some mysterious process in the solar nebula. Thus, meteoriticists
concluded
that chondrules were secondary products.
Three chondrites found in Antarctica (ALH 85085 and QUE 94411)
and the
Sahara (Hammadah al Hamra 237) are changing that view.
Investigators in the
U. S. and Europe may have found direct condensates from the solar
nebula in
those meteorites. Chondrules and grains of metallic iron-nickel
chondrules
tell the story of heat and wind in the solar nebula. The chemical
compositions of the chondrules indicate formation from a cloud
that had
become enriched in dust before being completely evaporated. When
the gas
cloud cooled, the tiny droplets condensed, but were blown into
much cooler
regions far from the Sun before they had a chance to acquire
moderately
volatile elements such as sodium, potassium, and sulfur. They
appear to have
accreted into asteroids before other processes affected them,
thus
preserving the record of heating and jetting in the nebula that
surrounded
the infant Sun. The results support new astrophysical theories of
chondrule
and star formation. (For details on these interesting meteorites,
see the
PSRD articles: Relicts from the Birth of the Solar System and The
Oldest
Metal in the Solar System.)
Meteorite Bonanzas in Cold and Hot Deserts
We know that extraterrestrial materials fall randomly on Earth;
it is simply
easier to find them in deserts where they are well preserved (due
to lack of
weathering) and concentrated on a plain background so that they
are easily
recognized. Successful meteorite searches in cold and hot deserts
have
dramatically increased the number of meteorite finds. While
Antarctica is
the premier cold desert hunting ground, researchers Ralph Harvey
(Case
Western Reserve University), Anders Meibom (Stanford University),
and
Henning Haack (University of Copenhagen) have been using remote
sensing
images to look at Earth's other ice sheet, Greenland, for
evidence of
meteorite stranding surfaces. Their work suggests that Greenland
would be an
excellent place for future meteorite hunts. Several hot desert
regions are
yielding huge numbers of meteorites, namely the Sahara Desert
(Algeria and
Libya), the Nullarbor Plains (Western and South Australia),
Mojave Desert
(Southern California), and high plains of Texas and New Mexico.
The three
most productive areas in the Sahara are the Reg el Acfer in
Algeria (at
least 320 meteorites), Dar al Gani (at least 256 meteorites) and
Hammahah al
Hamra (at least 520 meteorites) in Libya. Over 200 specimens have
been
collected from an unknown Saharan location (undisclosed by the
private
collectors). An additional 280 meteorites have been collected in
Australia's
Nullarbor Region.
To Boldly Look for Meteorites
Antarctic meteorites are collected, preserved, and documented
very
carefully. They've proven their extraordinary value to science
and to our
understanding of the history of the Solar System from its origin
in the
solar nebula to the formation of our Sun and planets. Collecting
meteorites
in Antarctica is like going on a field trip to the Moon, Mars,
and
asteroids. Last year, the eight ANSMET team members recovered 740
meteorite
specimens during their two-month field trip. This season's team
of ten will
return to Meteorite Hills to continue searching this portion of
the vast
East Antarctic Ice Sheet. These annual systematic collection
programs offer
the best chance of finding Martian meteorites and brand new types
of
meteorites inspiring new research, ideas, and discoveries.
============================
* LETTERS TO THE MODERATOR *
============================
(12) AL AMARAH STRUCTURE
>From Giesinger Norbert <norbert.giesinger@siemens.at>
Dear Dr. Peiser,
It should be possible to get satellite pictures of Al Amarah from
the
satellite Iconos with 4 / 1 m resolution. At this
resolution, a good sky
survey will be possible in order to decide if
it will make sense to mount an investigation on the ground. Under
the
current political circumstances, it will not be easy to get all
the permits
from Irak and the US (air force) to work there. Maybe CCNet
should collect
some money to order the pictures - I would donate a small sum (in
the range
of USD 20).
A remark concerning the scale of the impact on the middle east
civilisations: these were agrarian societies with low storage
capacity so
very dependent on enough annual rain. Regarding the appearant
impact of the
very local (man made) event of September 11 2001 on the
"Feeling" / mood of
significant parts of the population, I think an impact visible
all over
Mesopotamia and Egypt my well have shattered the believe system
and ego of
the priest cast.
Yours sincerely
Norbert Giesinger
Price lists etc see
http://www.spaceimaging.com/level2/level2products.htm
==============
(13) SALUTE TO ACC AND AN APPEAL TO THE SPACE FRONTIER GALA FOLKS
>From Andy Smith <astrosafe@yahoo.com>
Hi Benny and CCNetters,
This note is written to thank Arthur C. Clarke for all he has
done and
continues to do, to raise the level of awareness regarding the
great danger
we face, from the 100,000 or so rock bombs which are continually
circling
overhead and which strike our planet, with devastating results,
on a regular
basis.
We also want to thank Rick Tumlinson, the Space Frontier
Foundation, Bob
Bigelow, Hugh Heffner, and the many others, including all of the
CCNet
family, for the support they are giving to this important cause
and we want
to send a few specifics to the Gala participants.
First, it is iimportant to remember that we have a near-miss of
our orbit
about every half-hour (per Jim Scotti, at SPACEWATCH) and that
the risk of
another Tunguska or larger hit, in the next 25 years is about 1
in 4! This
is the greatest technical challenge in history and we are the
first
generation to have the capability to understand the danger and to
prevent
most impacts. However, we are moving much too slowly.
It is imperative that we get larger telescopes (like the 8 meter
super
asteroid telescope (LSST or DMT) on-line, as soon as possible and
that we
support Brian Marsden and the Minor Planet Center, in their
important
improvement of the global asteroid data-base. It is also
important that we
call attention to the asteroid danger in such national and
international
policy making groups as the Natural Hazards Caucus, of the U.S.
Senate, and
that we provide basic information to all of the appropriate
groups in the
United Nations and the nations of the world.
We really need an aggressive international program and modest
funding, if we
are to protect our planet and all of the life on it, from this
clear and
present danger. It will take both government and private support,
and there
is no time to waste.
At the present, very impressive NEO discovery rate, it will take
a few
centuries to get the NEO data we need. With one large and
dedicated asteroid
telescope, like the DMT, we can reduce this critical time to
about one
decade, according to a study by the U. S. National Research
Council. The
total costs, for the needed improvements is a few hundred
$million and this
is where we need the most help....it's information to the policy
makers and
funds for the critical projects. We salute the Gala and sincerly
seek more
help, while there is still time.
Cheers
Andy Smith
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