PLEASE NOTE:
*
CCNet DIGEST, 24 August 1998
----------------------------
(1) GREENLAND METEORITE SEARCH EXSPEDITION COMPLETED
Torben Risbo <tr@gfy.ku.dk>
(2) GREENLAND IMPACT & INTERSTELLAR NONSENSE
Duncan Steel <dis@a011.aone.net.au>
(3) SECOND METEORITE FALL FURTHERS STAR-CULT IN TURKMENISTAN
BBC Online Network
http://news.bbc.co.uk/hi/english/world/asia-pacific/newsid_156000/156974.stm
(4) WHAT THE HELL: I SIMPLY ENJOYED "ARMAGEDDON"
Jonathan TATE <fr77@dial.pipex.com>
(5) DOOMSDAY COMET HOAX: SAME OLD STORY & INFLATION
Mike Baillie <m.baillie@qub.ac.uk>
(6) MASS EXTINCTIONS ARE NOT UNIQUE
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) THE INSPIRATION OF ASTRONOMICAL PHENOMENA ("INSAP
II"),
Rolf Sinclair/NSF Physics Division <rsinclai@nsf.gov>
=====================
(1) GREENLAND METEORITE SEARCH EXSPEDITION COMPLETED
From Torben Risbo <tr@gfy.ku.dk>
Dear Benny Peiser
Following is a contribution for the CCNet. This is some genuine
stuff for consideration on the Greenland event. For further
information in the future contact the sources given below.
Sincerely
T. Risbo
------------------------------------------------------------
GREENLAND METEORITE SEARCH EKSPEDITION COMPLETED
The expedition to the target area on the Greenland ice sheet
border
zone near Frederikshaab Isblink returned to Copenhagen on August
19
after having spent 4 weeks searching for the remnants from the
bright
bolide observed over Southern Greenland in the early morning of
December 9 1997.
The task for the search was divided into two parts of equal
weight:
1. Search for fine grained remnants in the snow cover from the
last
winter.
2. Visual search for macroscopic remnants in the fall area.
The fall area was determined by analysis of the Nuuk video
recording
of the event and about 10 usefull visual observations from people
living in the towns of Nuuk, Fiskenaesset, Pamiut, Qaqortoq and
Narsarsuaq, supplemented by observations from trawlers operating
in
the waters East, West and South of Greenland. Observations from
satellites supported the findings. Analysis of the video was done
by
Holger Pedersen and Torben Risbo, Niels Bohr Institute AFG,
University of Copenhagen, the solution for the trajectory was
obtained in collaboration with Zdenek Ceplecha, Chech Academy of
Sciences. Eye witness reports were obtained by H. Pedersen on his
3
week travel to Greenland in January. The sighting of the Nuuk
video
was documented also. The solution for the trajectory pointed to
an
incoming track from the West at an inclination of approx. 35
degrees
to the horizon. The target area was initially given by a circle
with
a diameter of 8 km centered on 62.39 N 49.07 W located in the
border
zone of the ice sheet.
An precursor expedition in the target area was conducted by T.
Risbo,
H. Pedersen and Kim Pedersen, Kangerlussuaq and a TV crew from
Radio
Denmark with helicopter support from Greenland Air. This
expedition
supplied an overview of the conditions on the ice to be met by
the
main expedition to be launched in July. But most important a
number
of snow samples were recovered for quick analysis for possible
microscopic fall out be expected from the an explosive terminal
phase
of the meteorite due to its unusual large velocity.
40 snow samples of 2-3 kg were recovered representing the fall
out
from the last winters snow. The samples subjected to a
preliminary
analysis by T. Risbo at the Copenhagen University Arctic Station,
Qeqertarsuaq. The analysis suggested that some coloured mineral
grains of submillimeter size may be have been deposited in the
snow
following the Greenland event. This was based on their glassy
appearance, likely of beeing fragments from an explosion. Some
grains
have melted surfaces and even stumps from which glassy threds
have
been separated by melting. Colours were bright red, blue and
brown.
The distribution of this population over the target area was
different from the obvious geological material which have been
blown
into the ice surface from nearby nunataks and the surrounding
rocky
landscape. Atmospheric transportation of vulcanic glasses to the
area
is excluded due to the size of the grains.
The findings of the main expedition support this view. Aprox. 200
snow samples have been collected each containing 10 kg of snow.
In
addition a "production platform" was put up on a site
well away from
land. This consisted of a long black plastic sheet and it
delivered 1
ton of melt water through a filter. The preliminary microscopic
inspections in the field of these samples confirm the early
findings of
the precursor expedition of June.
Analysis of this material is about to be organized and is to be
taken
care of by the Geological Museum of Copenhagen University in
close
collaboration with the Geophysical Department of Niels Bohr
Institute
AFG. No statements on the possible meteoritic origin of the
material
are possible at the moment.
The second task of the expediton did not result in collecting any
macroscopic remnants. The search area was entended to the north
and
some 800 km**2 of ice surface have been surveyed from low level
helicopter flights. Small selected areas were covered by the
menbers
on foot. No large search and coverage on foot was possible due to
the
very heavy crevassed ice surface. It is very difficult to assess
the
probability of finding a fragments of a given size. Very big
fragments like house sized objects are not present. Golf ball
sized
objects cannot be excluded.
As a comparison the Vaca Muerte meteorite fall in the Atacama
Desert
of Chile was searched and collected by one of us (H. Pedersen).
The
fall area was represented by an ellipse of area 12 km**2 and 130
pieces representing some tons of material were collected in 120
field
days in a terrain very easy to access and cross by a car.
The trajectory is under refinement following reanalysis of the
video
frames now separated into half frames. The atmospheric intrance
velocity is constrained by analysis of the Nuuk video sequence.
The
full light phenomenon of the bolide is contained in 100 video
frames
representing 4 seconds of real time. The video system is PAL
running
at 25 frames per second (50 half frames interlaced). Many visual
eye
witnesses confirm that the light phenomenon was over within very
few
seconds. Satellite data are going to be incorporated into the
trajectory solution and should also confirm the fastness of the
phenomenon. No final solution for the trajectory is available at
the
moment. Evidence points to an entrance velocity in excess of 50
km/sec. A simple pedestrian estimate based on the duration
of the
light and the geometry of the track also supports such a number.
The name of Kangilia is coined for the Greenland meteorite event
in
case that remnants are veryfied. Nunata Kangilia is the piece of
solid land closest to the target area and given a name on the
map.
"Nunatak" is a land surrounded by the ice,
"kangilia" means most
eastward of most remote. The chairman of the Greenland Home Rule
mr.
Jonathan Motzfeldt suggested the name upon inspection of
the
beautifully coloured microscopic possible remnants at the Arctic
Station, Qeqertarsuaq.
-----------------------------------------------------------------
Information on analysis of video and the trajectory:
Holger Pedersen, Niels Bohr Inst: pedersen@astro.ku.dk
Torben
Risbo
-
: tr@gfy.ku.dk
Information on analysis of samples.
Torben Risbo, Niels Bohr Inst. : tr@gfy.ku.dk
Asger Ken Pedersen: Geolog. Museum akp@savik.geomus.ku.dk
Information on the Greenland event general:
http://www.astro.ku.dk/~holger/greenland.html
(Holger Pedersen)
Some pictures of "glassy" grains from the precursor
expedition:
http://www.dr.dk/ddr/color/meteor/metebil.htm
(Denmark Radio-
online)
http://cnn.com/TECH/science/meteorite.search/index.html
(CNN-
online)
Information on the field work general:
http://www.dr.dk/ddr/color/meteor/meteor.htm
http://www.astro.ku.dk/tycho/tbe98/
-------------------------------------------------------------
Torben Risbo
Coordinator of the Greenland Meteorite Search &
Member of Expedition Steering Committee.
Niels Bohr Institute AFG, Geophysical Department,
Juliane Maries Vej 30, DK 2100 Copenhagen O, Denmark
tr@gfy.ku.dk +45 35320585, +45
35320602 (sekr.)
====================
(2) GREENLAND IMPACT & INTERSTELLAR NONSENSE
From Duncan Steel <dis@a011.aone.net.au>
Dear Benny,
Regarding the 'interstellar meteorite lands in Greenland' story:
>Calculations based on the video frames of the meteorite's
descent,
>which lit up the night sky over Greenland on Dec. 9, put its
velocity
>at 35 miles per second, or one and a half times the maximum
speed of
>any known meteorite in our solar system, Christensen said.
This is nonsense. 35 miles per second is equivalent to about 56
km
per second. The limiting speed is actually about 74 km per
second.
This is easily calculated as follows.
At any heliocentric distance r an object with semi-major axis a
has a
speed (v) given by
v^2 = (GM/1 AU) ((2/r) - (1/a))
(GM/1 AU) is about 29.8 km/sec; the Earth's speed various between
about 29.3 km/sec (in early July) to 30.3 km/sec (in early
January)
because for our planet r varies between 1.0167 and 0.9833 AU
respectively.
The highest value of a which is possible for an orbit bound to
the Sun
(i.e., a parabolic orbit at the limit, eccentricity e=1) results
from
having a ==>> infinity, thus 1/a = 0. Thus the
maximum speed is
root(2) times the terrestrial speed. Doing the sums when
the Earth
is at perihelion (0.9833 AU), for an object with inclination 180
degrees and also having q=0.9833, it meets us head-on. Thus
the
relative speed would be:
v_rel = (1 + root(2)) * 30.3 = 73.15 km/sec
The actual impact speed (say, the speed at h=100 km before any
appreciable atmospheric deceleration has occurred) is the above
v_rel
added in quadrature (sum the squares and take the square root)
with
the terrestrial escape speed of about 11 km/sec, the answer being
close to 74 km/sec.
On the other hand, it is also possible for hypothetical objects
from
interstellar space to meet the Earth at speeds WELL BELOW the
above:
it all depends upon their radiant (e.g., an object with i = 0
degrees
but q=0.9833 would catch the Earth up from behind, thus having
v_rel = (root(2) - 1) * 30.3 km/sec
However, if all one has to go on is a speed, then 74 km/sec is
the
limit.
Some useful background on this is given by, for example, Marsden
&
Steel in the 'Hazards Due to Comets and Asteroids' book (ed. T.
Gehrels), and also the paper by myself you cited in a CCNet
posting
last week:
D.I. Steel, 'Distributions and moments of asteroid and comet
impact
speeds upon the Earth and Mars,' Planetary & Space Science,
46,
473-478 (1998).
or in:
D.I. Steel, 'Collisions in the solar system -V. Terrestrial
impact
probabilities for parabolic comets,' Monthly Notices of the Royal
Astronomical Society, 264, 813-817 (1993).
The problem of identifying interstellar meteoroids is discussed
in
the NATURE paper by Taylor, Baggaley & Steel I cited before,
plus
(more extensively) in the papers referenced therein.
(Lots of other people have published on these topics over the
years,
but of course I have my own papers to hand listed in my CV)
In short: the media reports seem daft, perhaps based upon
comments by
people unfamiliar with the relatively simple physics involved (as
above).
Duncan Steel
=====================
(3) SECOND METEORITE FALL FURTHERS STAR-CULT IN TURKMENISTAN
From the BBC Online Network
http://news.bbc.co.uk/hi/english/world/asia-pacific/newsid_156000/156974.stm
Meteors and comets have been worshipped for centuries
In Turkmenistan, the fall of two meteorites within a month is
being
seen as a holy happening, causing a flurry of interest in the
small
desert state.
The latest fell on a village just over 100km from the site of the
first, reportedly crashing through the roof of a house.
News of the second meteorite, which fell at the end of July, is
only
just emerging as villagers refused to report the incident.
They believed the small object from the skies, weighing about a
kilogramme, to have religious significance.
It has been taken to the capital, Ashkhabad, for study by
scientists.
The second "holy stone" follows the fall of one of the
largest
individual meteorites in history - weighing 820 kilogrammes -
near a
spiritual site in eastern Turkmenistan.
The BBC Central Asia Correspondent, Louise Hidalgo, says
Turkmens
hailed its arrival near the old capital of the ancient state of
Khorezm
as an auspicious event as it coincided with the sixth anniversary
of
the election of their leader, President Niyazov.
Witnesses who saw the meteorite fall spoke of a bright light and
tremendous noise, and earth tremors which were felt up to a 100km
away..
And the meteorite, now on show in a museum, is to be named
"leader of
the Turkmens" in honour of the president.
Copyright 1998, BBC
===============
(4) WHAT THE HELL: I SIMPLY ENJOYED "ARMAGEDDON"
From Jonathan TATE <fr77@dial.pipex.com>
I have finally been to see what is probably the most harangued
movie in
scientific history! Having read the postings on various
astronomically
orientated news groups I arrived at the cinema ready to be wildly
disappointed, and annoyed by the lack of accuracy that I had read
so
much about. What I am about to say will probably condemn me as a
heretic, but what the hell!
Well, a science lesson it is certainly not. There are countless
"nit-picks", some truly "nit", and some
actually elephantine! But the
film was made to entertain, not to educate. So, did it
entertain? You
bet! As a good rip-roaring adventure story it is excellent; there
is
plenty of daring-do, a nice, but not overpowering love interest
and
masses of great special effects. The plot doesn’t take a
genius to
predict, but the same applies to most films these days.
Many people have been disappointed by the lack of scientific
accuracy,
indeed some have been positively "anoraky" in their
criticism. There is
no doubt that more accuracy could have been incorporated, but it
wouldn’t have taken much to introduce a "yawn
factor", killing the film
stone dead. The general public want to be entertained, not
educated in
a cinema. After seeing "Armageddon" most will come away
with a pink
fuzzy feeling, and an increased awareness of the impact threat.
They
might not know as much as some, but they will know that the
hazard
exists. That is half of the battle won.
Now, it would be very easy to pontificate about the scientific
gaffs,(aren’t I clever - I know more than you), and become
an instant
bore. Let’s face it, most science IS boring to the
uninitiated, so it
would be a huge error of judgement to spoil one of the few media
events
dealing with the impact threat for the sake of some esoteric
quibbles.
If "Armageddon" raises the public perception of the
impact threat, and
generates some interest then the errors can be forgiven - never
let the
truth get in the way of a good story. I am a professional
soldier, but
if I picked holes in every war film that I saw I would truly be
Mr
Boring (my wife is convinced that this has already happened). The
same
applies to most occupations - what about "Casualty",
"ER", "The Bill"
or "Frost"? You don’t see other professions
getting heated about
technical errors in films or TV programmes, they just revel in,
and
take advantage of the publicity.
"Deep Impact" and "Armageddon" are very
different films, but both
portray the threat from asteroidal or cometary impacts in a
fairly
responsible and tolerably accurate fashion. We should concentrate
on
using the positive aspects of both for our purposes, and trying
to
avoid becoming terminally boring about their shortcomings.
Bottom line? Go and see "Armageddon" with a big pack of
popcorn, and
prepare for a roller-coaster ride! Watch out for the Paris bit -
tee-hee! (Apologies to our French members, but remember the
Battle of
Hastings!)
Jay Tate
=====================
(5) DOOMSDAY COMET HOAX: SAME OLD STORY & INFLATION
From Mike Baillie <m.baillie@qub.ac.uk>
By a quirk of fate I happened to have the Feb 13 1996 copy of the
Weekly World News which carried the "Hubble Finds Doomsday
Comet (and
it's speeding towards Earth)" story. Interestingly the comet
was the
"size of Europe" even in 1996 but otherwise inflation
has clicked in.
Then it was $2.6 billion emergency expenditure, now it's $4
billion;
then it was an estiated 2 billion dead, now it's 3 billion.
However,
the expert Dr Clemson is almost the same, in 1996 he was Dr
Cremson.
The big change, consistent with reality, is that in 1996 they
were
confidently working towards shooting it down with a NASA rocket
adapted
to carry a nuclear payload ("to vaporize the comet while it
is still
safely out in space"), now they're basically saying that
won't work,
but we might as well try anyway, as nothing is to be lost. So,
even in
the lunatic fringe, the message is moving in the right direction.
They
are recognising that we can't do anything about a directly
approaching
comet, and the casualty figure has risen to one half of the real
figure. It looks as though we still have to get the message over
that
size is important.
Mike Baillie
Palaeoecology Centre
School of Geosciences
Queen's University, Belfast
======================
(6) MASS EXTINCTIONS ARE NOT UNIQUE
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Public Relations
University of Cincinnati
Contact: Chris Curran
(513) 556-1806 (O)
chris.curran@uc.edu
August 20, 1998
UC Geologist Finds Evidence That Mass Extinctions Are Not Unique
in
Affecting Global Diversity Trends
Cincinnati -- The dramatic effects of the mass extinctions
recorded in
Earth's geologic record have led many geologists to view them as
a
distinct class of events -- so powerful that they swamp out
normal
evolutionary processes. Others have argued the opposite, that
over
geologic time, mass extinctions have had little effect on global
diversity trends.
University of Cincinnati geologist Arnold Miller argues in a
review
paper in the August 21 issue of Science that the truth is
somewhere in
the middle of those extreme views. Miller's evaluation of global
marine
diversity patterns through the Phanerozoic, in light of recent
research, indicates that mass extinctions are simply the most
globally
extensive of a continuum of abrupt transitions that combine to
affect
overall global diversity. The Phanerozoic covers the pasts 540
million
years.
That view is in contrast to Stephen Jay Gould and others who have
viewed mass extinctions as an over-arching tier of evolutionary
processes, distinctly different than the processes which occur in
the
intervening time periods.
"While I agree that mass extinctions are the largest and
most important
of a class of 'catastrophes,' I would argue that they are not
fundamentally different as an evolutionary mechanism from what
causes
diversity change in the intervals between them," said
Miller. "The
so-called background intervals are also built of catastrophes
that are
more local or regional in scope, but can have the same profound
effect
on a local biota that a mass extinction has on a global
biota."
As an example of an abrupt regional change, Miller discusses the
diversification of a group of organisms known as "biological
bulldozers," which dig into deposited sediments to find
food. The
geologic record includes cases where the bulldozers replaced
another
group known as ISOSS (immobile suspension feeders on soft
substrates).
Previously, researchers believed the biological bulldozers
out-competed
the ISOSS organisms. Miller suggests an alternative explanation.
"Many deposit-feeders favor muddy, nutrient-rich sediments
as a
substrate to occupy. Just such sediments were provided during key
intervals as a consequence of eroding areas uplifted during
mountain-building. Quite apart from the action of the bulldozers,
many
of the incumbent immobile types would not have liked this kind of
habitat. So I am suggesting, as an alternative to the above
'competitive' scenario, that the transition happened because of
major,
physical changes to habitats."
In fact, previous research reported by Miller and others on the
Ordovician Period showed that diversification of certain groups
was
favored in areas where active mountain-building took place.
As for those who argue that mass extinctions are actually minor
contributors to global diversity patterns, Miller has used his
database
of Ordovician fossil occurrences to demonstrate that regional and
local
bursts of diversification occur at different times around the
world.
Over time, the bursts add up to present what Miller believes is a
misleading picture of diversification trends a smooth, gradual
change
over geologic time.
"The global pattern does not match any localized
pattern," said Miller.
"The global diversity trend is misleading for what it says
about the
rates of transition and perhaps even for what causes them."
Miller's research is supported by NASA's Program on Exobiology.
==================
(7) THE INSPIRATION OF ASTRONOMICAL PHENOMENA ("INSAP
II"),
From Rolf Sinclair/NSF Physics Division <rsinclai@nsf.gov>
Dear Colleague:
With this note, we wish to inform you of the up-coming Second
International
Conference on
THE INSPIRATION OF ASTRONOMICAL PHENOMENA ("INSAP II"),
to be held 7-14 January 1999 on The Mediterranean Island of Malta
[ Website http://ethel.as.arizona.edu/~white/insap2.htm
]
The sky makes up half of mankind's world; the Earth around us
makes up
the other half. This meeting will explore mankind's fascination
with
the astronomical phenomena that define the sky -- the
lights in the
sky, by day and by night -- which have been a strong and
often
dominant element in human life and culture. Scholars from a
variety of
disciplines (including Anthropology, Archaeology, Art, Classics,
History and Prehistory, Mythology and Folklore, Philosophy, the
Physical Sciences, and Religion) will attend "INSAP
II" to discuss the
impacts astronomical phenomena have had on mankind.
Presentations by
attendees will be grouped under four main topics: Literature;
Art; Myth
and Religion; History and Prehistory.
Invited presentations will include (tentatively):
Albert Boime (Art History, Univ. of California-Los Angeles):
"The
Artistic Portrayal of Starry Skies";
Madanjeet Singh (UNESCO, Paris): "The Sun, Symbol of Power
and Life";
John David Mooney (artist, Chicago): "Chicago: Vega and
Horizon Astronomy"
Charles Camilleri (composer, Univ. of Malta): "Space and
Music
Inspiration" (world premier).
Other presentations submitted include:
Imad A. Ahmad (Bethesda, Maryland): "Astronomical
Inspiration in the
Rubayyat of Umar Khayyam"
Mats Bjorkin (Stockholm Univ.): "Shooting Stars: Cinema and
Astronomical Imagination"
Alberto Cappi (Osservatorio Astronomico di Bologna): "The
Cosmology of
Edgar Allen Poe"
Sharon Daniel (Univ. of California-Santa Cruz):
"Computer-Based
Interactive Art"
Harald Gropp (Univ. Heidelberg): "The Nearly-Forgotten
Calendar of Coligny"
John Hatch (Univ. of Western Ontario): "Models of the
Universe and their
Role in the Development of 'Abstract' Art"
Christopher Impey (Univ. of Arizona): "Reacting to the Size
and Shape of
the Universe"
Daniel Oberti (Sculptor, Sebastopol, California): "Sundials
and Moon
Disks"
Adrian Otoiu (University of the North, Romania): "When the
Stars
Go Astray"
Daniel Varisco (Hofstra Univ.): "The Mystical Symbolism of
the Lunar
Stations in Medieval Islamic Cosmology"
Skawomira Zeranska-Kominek (Univ. of Warsaw): "Possession
and
Inspiration: The Musician Between Day and Night"
The Conference will allow the attendees to address the many and
variegated cultural impacts of the perceptions of the day and
night
skies, providing a mechanism for a broad group of artists,
historians,
philosophers, and scientists to meet, compare notes, and
have the
chance to ask those questions of each other about their work
which may
have been lying fallow for decades. Attendance will be by
invitation
from among those applying. Full information on the Conference and
an
application form can be obtained by contacting the
Organizing
Committee, or from our Website
(http://ethel.as.arizona.edu/~white/insap2.htm).
Although the nominal
deadline has passed, the selection committee will be happy to
receive
applications while they are deliberating over those on-hand. The
absolute close-off date will be, however, 25 August 1998; even
with the
use of Email, the committee needs a little time to devise a
program out
of the pile of applications!
This Conference is the second to be held on this general theme.
Details
of the first meeting (held at Castel Gandolfo, Vatican State, 27
June-2
July 1994), and the publication references that include
many of the
papers presented there, may be found at
http://ethel.as.arizona.edu/~white/insap.htm
.
This Conference is sponsored by the OTS Foundation and the
Vatican
Observatory.
Please circulate or post this announcement.
The Organizing Committee:
Professor Raymond E. White, Steward Observatory, University of
Arizona
(Chair) (rwhite@as.arizona.edu)
Rev. George V. Coyne, S. J., The Vatican Observatory: (gcoyne@as.arizona.edu)
Dr. Rolf M. Sinclair, National Science Foundation, Arlington VA
(rsinclai@nsf.gov)
Prof. Frank Ventura, Malta (fven@cis.um.edu.mt)
----------------------------------------
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