PLEASE NOTE:
*
CCNet DIGEST, 9 July 1999
--------------------------
MALCOLM MILLER'S THOUGHT FOR THE DAY
DIRTY SNOWBALL?
Halley's Comet. I'm one of those who've
seen it.
Almost a generation's passed since it
was here,
A modest cosmic windsock, quite hard to
see
Against the light of even this small
city's glare,
And almost universally decried -
'is that all?'
I watched it for a year, quite
unspectacular,
But bringer of a special thrill. He saw
it, Edmund,
And before him how many millions saw it
Each three quarter century in star-dark
skies?
I wonder who of those alive this day
Will see it back again in twenty sixty,
Or if they'll even care about what
Halley guessed?
Malcolm Miller
<stellar2@actonline.com.au>
(1) GREAT BALLS OF FIRE
Joel Schiff <j.schiff@auckland.ac.nz>
(2) OBSERVATORY ON TRAIL OF FIERY SPACE ROCK
New Zealand Herald, 9 July 1999
(3) PREPARING FOR DEEP IMPACT
ABC NEWS ONLINE, 9 July 1999
(4) WHAT CAUSED THE DESERTIFICATION OF THE SAHARA
Doug J Keenan <dj.keenan@virgin.net>
(5) IMPACTS RATES
Timo Niroma <timo.niroma@tilmari.pp.fi>
(6) DNA ON THE ROCKS
INSCiGHT, 8 July
=================
(1) GREAT BALLS OF FIRE
From Joel Schiff <j.schiff@auckland.ac.nz>
Dear Benny,
Like with most fireball events, there are a lot of spurious media
reports that are bandied about and this recent New Zealand event
is no
exception. Speaking to the media over the telephone is an
especially
dangerous activity. When I told a New Zealand Herald reporter
that
since the object had detonated in the atmosphere, if people were
to
search to ground for any meteorite fragments they could be pea to
apple
size, but instead, it came out that the object in space was this
size,
a matter I certainly would not have speculated on. To a reporter
these
are incidental matters, and perhaps that is why they are not
scientists.
There were also reports that fragments came down over Napier
which is
over on the East coast (North Island), but the trajectory data so
far
points to a fall area over Taranaki on the West coast (North
Island). At
the moment this area is 100 km long and half of it is out to sea.
Further eyewitness reports are being coordinated by Dr Ian
Griffin of
the Auckland Observatory in order to refine the trajectory.
So far there has not been one fragment recovered from this event
although I have already seen a number of volcanic rocks, a road
stone
with tar on it, etc.
Joel Schiff
===============
(2) OBSERVATORY ON TRAIL OF FIERY SPACE ROCK
From New Zealand Herald, 9 July 1999
[http://www.nzherald.co.nz/nzherald99/story.cfm?theStoryID=10070]
Friday, July 9, 1999
Observatory on trail of fiery space rock
By Philip English
The Auckland Observatory is confident of plotting the path of the
meteorite that blazed over central New Zealand on Wednesday.
A dealer in New York offered $US25,000 ($47,465) for its remains
yesterday.
Staff of the observatory at One Tree Hill were on the job at 4
am,
collating observations of the meteorite's course in a tracking
exercise
that could take several days.
By late yesterday the director of the observatory, Dr Ian
Griffin, said
the impact area had been narrowed to a 100km-long strip in
Taranaki,
perhaps half in the sea and half on the land.
"It is a long and drawn-out process but we are slowly
working it through."
Dr Griffin said observers were being questioned to define the
area more
specifically for scientific purposes.
The observatory had no clues to how big the meteorite was.
As it travelled through space, it could have been anything up to
the
size of a chair.
Coming through the atmosphere at 60km to 80km above Earth, it
would
have broken into fragments, perhaps too small to see on the
ground
after being consumed in the fireball.
Depending on the geography of the land, there could be a chance
of
finding a fragment, said Dr Griffin.
"If there was a big enough crater, you might see it."
Institute of Geological and Nuclear Sciences seismographs picked
up the
boom of the meteorite as it crashed through the atmosphere,
evidence
likely to be used by the observatory in the tracking exercise.
The editor of Meteorite magazine, Dr Joel Schiff, of the
University of
Auckland maths department, was inundated with calls from people
believing they had parts of the meteorite or earlier meteorites.
A dealer he knew in New York had offered $US25,000 for the
meteorite.
"He has put this money up front. I think he is
serious."
A truck driver in Hawkes Bay whose windscreen was cracked by
something
when no other traffic was around produced a rock the size of a 5c
piece.
"It looked like a piece of road metal to me," said Dr
Schiff.
"It had some black stuff on it which instead of being fusion
crust
looked like tar."
© Copyright 1999, NZ Herald
=============
(3) PREPARING FOR DEEP IMPACT
From ABC NEWS ONLINE, 9 July 1999
http://abcnews.go.com/sections/science/DailyNews/deepimpact990709.html
PREPARING FOR DEEP IMPACT
Spacecraft to Fire 1,100-Pound Bullet at Comets Core
By Matthew Fordahl
The Associated Press
L O S A N G E L E S, July 9 A
spacecraft named Deep Impact will
fire a 1,100-pound copper bullet at the nucleus of a comet,
blasting
out a crater the size of a football field and as deep as a
seven-story
building.
The radical $240 million mission, approved Wednesday by
NASA
administrators, may sound more like fiction than science, but its
primary purpose will be to study the makeup of comets.
Its a coincidence that the project has the same name as
last summers
disaster movie Deep Impact, which was about a comet smacking
Earth,
mission planners said Thursday.
The name was selected prior to the movie, said James
Graf, Deep
Impacts project manager at NASAs Jet Propulsion
Laboratory in
Pasadena, Calif. It wasnt inspired by it.
Studying the Inside
Deep Impact is scheduled to be launched in January 2004 and will
arrive
at comet Tempel 1 on July 4, 2005. The projectile will separate
from
the spacecraft and hit the comet at 22,300 mph.
Shortly after impact, the craft will come within 300 miles of the
comet
surface and send back data and pictures of the debris and crater.
It
will eventually zoom off into space.
Comets are believed to be remnants from the early days of the
solar
system, and several missions are planned to observe them
close-up. Deep
Impacts projectile, however, will be the first to crash
into one.
Deep Impact will allow scientists to study the inside of a comet
by
observing the debris ejected from the crater. It can
give us an
understanding of what the solar system looked like during its
formation, and what contributions comets may have made to our
life here
on Earth, Graf said.
Visible from Earth
The impact should be visible from Earth 83 million miles
away with
the aid of a telescope. The mission poses no threat to Earth,
Graf
said. The impact crater will be small compared with the overall
size
of the comets nucleus.
NASAs approval of Deep Impact was made less than two weeks
after the
space agency pulled the plug on another mission to the same
comet.
Space Technology 4/Champollion would have landed on Tempel 1 and
drilled beneath the surface.
NASA administrators decided to favor Deep Impact because it was
focused
solely on science and fit into existing budget plans, said Doug
Isbell,
a NASA spokesman in Washington, D.C.
Copyright 1999 The Associated Press.
===========
(4) WHAT CAUSED THE DESERTIFICATION OF THE SAHARA
From Doug J Keenan <dj.keenan@virgin.net>
Hi Benny,
In the July 8th CCNet Digest item on the desertification of
the
Sahara, it says that copies of the original paper can be obtained
from Harvey Liefert at AGU. The paper is now available directly
on
the web at the following addresses (in HTML and PDF formats,
respectively).
http://www.agu.org/GRL/articles/1999GL900494/GL905W01.html
http://www.agu.org/GRL/articles/1999GL900494/GL905W01.pdf
I had a look at it. The paper is not really about the 4K BP
event:
the event is mentioned only briefly, and none of the main work on
the
event is cited.
The paper is about the permanent shift in Saharan climate and
vegetation that occurred about 6000 years ago. The paper presents
good evidence that atmosphere-vegetation feedbacks can greatly
amplify other climate forcings. The (external) climate forcing
considered is orbitally-modulated insolation; in principal,
though,
it might also be a comet, volcano, etc. (assuming other aspects
of
the climate system permitted multiple equilibria).
Cheers,
Doug Keenan
============
(5) IMPACTS RATES
From Timo Niroma <timo.niroma@tilmari.pp.fi>
Dear Benny,
Dear Michael,
Michael Paine wrote that a Canadian webpage did not contain any
craters of a size larger than some meters during the last 50,000
years. Here is a list of the last 7,000 years of craters
exceeding
50m. Theoretically, the list cannot be complete, given that a new
crater is found every few years even in this category.
Practically
the list can't be complete because there are many craters whose
age
has not yet been determined. And last but not least, my list was
compiled in 1997, so there may be later identifications to add
yo this list. Please do so, if you know of any new discovery.
I looked at the Canadian website. It was under construction, it
even
changed during the period I looked at it.
So the list of craters dating from the last 7000 years is as
follows:
Mache (or Macha) (Russia) 7000BP or 5000BC 300m
Henbury (Australia) 5000BP or 3000BC 157m
Boxhole (Australia) 5000BP or 3000BC 170m
Campo del Cielo (Argentina) 4000BP or 2000BC 50m
Rio Cuarto (Argentina) 4000BP or 2000BC several in a row, the
greatest 4.5 km
Kaalijarvi (Estonia) 4000BP or 2000BC 110m
Wabar (Saudi-Arabia) most probably AD, 100m
We can see that during the late Holocene the Rio Cuarto crater(s)
are
by far the greatest (known). It may be one of the causative
agents to
the happenings in 2000-2500 BC.
Regards,
Timo Niroma
PS. Look at the great heap 5000-4000 years ago.
============
(6) DNA ON THE ROCKS
From INSCiGHT, 8 July
[http://www.academicpress.com/inscight/07081999/graphb.htm]
8 July 1999, 5 pm PST
DNA on the Rocks
By Lone Frank
Scientists say they have, for the first time, extracted DNA from
ancient ice core samples in northern Greenland. The success may
usher
in a worldwide hunt for ancient microbes trapped in ice.
A team led by evolutionary biologist Peter Arctander of
Copenhagen
University used the polymerase chain reaction (PCR) to amplify
fragments of well-characterized genes in ice cores dated to 2000
and
4000 years ago. After sequencing the recovered fragments, they
compared
them to known sequences in a database and found that the ice
cores held
the remains of a surprising diversity of life forms: at least 57
distinct organisms, including several types of fungi, algae,
protists,
and a class of conifer, they report in the 6 July issue of
Proceedings
of the National Academy of Sciences.
"No one expected such a variety of fungi to be
present," says Andrea
Gargas of the University of Wisconsin, Madison, a specialist on
fungal
DNA. "We have found samples trapped under glaciers that were
only from
two different fungal groups," she says. "You always
think of [that]
environment as a bit more sterile because it's so remote and
because of
the lack of nutrients." And there's more to come, says
Arctander: So
far they've only toted up the eukaryotic organisms -- those with
nuclei. The number of bacterial species, he says, should be far
greater.
Previously, the study of ancient microbial life in ice cores was
mostly
limited to the identification of plant pollen and spores, says
Arctander. But PCR has opened up a wealth of new possibilities.
Co-author Anders J. Hansen now plans to look at the DNA of plant
material in 6000-year-old Greenland ice, to see which plants were
available around the time the first humans are thought to have
migrated
there from northern Canada. And his colleague Eske Willerslev
plans to
sample ice cores from Siberia, Canada, and Antarctica to compare
microbial life and find out how long DNA can stay intact.
DNA analysis will also enhance climate studies, says Henrik Brink
Clausen of The Niels Bohr Institute in Copenhagen. Adding
biological
information to atmospheric data from ice cores, he says,
"will provide
a much more accurate picture of climate and changes over
time."
© 1999 The American Association for the Advancement of Science
[Extracted from INSCiGHT, Academic Press.]
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UK TASK FORCE TO STUDY ASTEROID THREAT
From Graham Richard Pointer <grp1@st-andrews.ac.uk>
Dear Dr Peiser,
I saw this on the Daily Telegraph site
http://www.telegraph.co.uk:80/et?ac=000627142853006&rtmo=3qwxBHwM&atmo=F
FFFFamX&pg=/et/hupdate.html#go6
Yours sincerely,
Graham Pointer.
Task force to study Asteroid threat
THE GOVERNMENT is considering what can be done to prevent
the "serious"
risk of earth being hit by an asteroid, it emerged today.
After a meeting with Liberal Democrat MP Lembit Opik, Science
Minister Lord
Sainsbury has agreed to consider putting together a group of
experts to
study the threat from "near earth objects".
"It produces in most people a fairly good giggle factor and
people say it's
not an issue. But it is an issue," warned Lord Sainsbury.
"It is one of
those issues which has a very low probability of happening.
We are talking about something that could happen, say once every
100,000
years, so I have got to say I don't stay awake at night worrying
about it,"
Lord Sainsbury told BBC Radio 5 Live's Breakfast Show.
Claiming that someone was 750 times more likely to die in
an asteroid
impact than win the lottery this weekend, Mr Opik said:
"There are at least
1,500 objects which could hit us and over time something
definitely will." He suggested a network of telescopes
around the world to
see if anything was heading for Earth.
Copyright 1999, the Daily Telegraph