PLEASE NOTE:
*
CCNet 81/2001 - 22 June 2001
----------------------------
"A previous eclipse seen in southern Africa led to the
greatest
disaster in British military history. [...] On January 22, 1879,
the
Battle of Isandlwana (in the province of South Africa now known
as
KwaZulu Natal) led to the death of 1,329 out of about 1,700 men
on
the British side. Of the Zulu army of around 20,000 warriors, or
impis,
about three thousand were killed. [...] It seems clear that
events would
have been quite different if there had been two scientists
vailable to
the generals. One would be an astronomer, to tell them that an
eclipse
was imminent, and another an anthropologist, to inform them how
the Zulu
might react. That is projecting modern values on a wartime
disaster from
more than a century ago, but in describing events on that dark
day, the
role the eclipse played is often neglected."
--Duncan Steel, The Guardian, 20 June 2001
"As spallation fragments come from at or near the target's
surface
they are ejected in the very early stage of the formation of the
impact crater. Because of this they are generally only lightly
shocked
and this may allow organic materials, or living cells, to survive
far more
readily than would be the case for heavily shocked material
produced by the
far higher cometary impact velocities. This suggests that
asteroid
collisions will be quite capable of getting low-mass high
velocity
fragments off Mars and into Earth-crossing orbits. The question
is whether
or not any of these small fragments can survive the descent
through
Earth's atmosphere and conserve any living Mars-bugs."
Richard Taylor, Probability Research Group, 20 June 2001
"I wonder if we could put a number of "space
clouds" in relatively
low Earth orbit. I envisage them as being rather like large
balloons,
reflecting solar radiation away from the Earth. If they were
large
enough the effect would be similar to a solar eclipse. Their
number could
be varied as needed to increase or decrease the cooling
effect."
--John Youles, Beckenham, Kent, England, UK
(1) DARK DAYS OF WAR
The Guardian, 20 June 2001
(2) LIFT OFF FOR ROSETTA AT LE BOURGET
ESA News, 20 June 2001
(3) ARIANE TO LAUNCH ROSETTA EXPLORATION SATELLITE
Yahoo News, 19 June 2001
(4) NASA'S TERRA SATELLITE CAPTURES A WORLD OF SUNLIGHT AND HEAT
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) UK SPACE CENTRE PREPARES FOR LAUNCH
BBC News Online, 19 June 2001
(6) EUROPEAN ASTRONOMY IN THE 20TH CENTURY
Wolfgang R. Dick <wdi@POTSDAM.IFAG.DE>
(7) ASTEROIDS RATHER THAN COMETS
Richard Taylor <richard.taylor3@virgin.net>
(8) TR/J EXTINCTION BOUNDARY
Hermann Burchard <burchar@mail.math.okstate.edu>
(9) SPACE PARASOL
John Youles <j.youles@ntlworld.com>
(10) REFRESHING SKEPTICISM
James Perry <AJDPerry@aol.com>
(11) SHAPING PUBLIC ATTITUTES TO TECHNOLOGY & INDUSTRIAL
PROGRESS
Stephen Ashworth <sa@astronist.demon.co.uk>
(12) TERRESTRIAL EVIDENCE OF A NUCLEAR CATASTROPHE IN PALEOINDIAN
TIMES?
Bob Kobres <bkobres@uga.edu>
(13) AND FINALLY: AFRICA ON RIOT ALERT OVER FIRST ECLIPSE OF
MILLENNIUM
The Independent, 21 June 2001
=============
(1) DARK DAYS OF WAR
From The Guardian, 20 June 2001
http://www.guardian.co.uk/Archive/Article/0,4273,4207702,00.html
The eclipse over southern Africa today reminds Duncan Steel of a
dark hour
in 1879 that led to military disaster
Wednesday June 20 2001
The Guardian
Twenty months ago, much of Britain came to a standstill as people
gawked
sunward through their safety goggles. In Cornwall and Devon - the
only
places in England where totality could be experienced - things
really did
come to a halt, with gridlocked roads.
Across Europe and the Middle East tens of millions of people
watched a total
eclipse. There have been no total solar eclipses anywhere since
then, until
today. At just after 10:30am (British Summer Time) an eclipse
track will
touch down in the South Atlantic, not far off the coast of
Uruguay. Sweeping
rapidly eastward, its path will swell until it is more than 120
miles wide,
producing totality for almost five minutes (twice as long as that
on August
11, 1999).
As it leaves the ocean, the eclipse track crosses Angola, Zambia
(including
Lusaka), parts of Zimbabwe and Mozambique, and finally the
southern part of
Madagascar. It fizzles out soon after 3:30pm in the Indian Ocean.
Rest
assured that there will be plenty of keen eclipse watchers
arrayed along
that path as you read this.
The Zambian government has already cautioned its citizens to
expect this
entirely natural event. Perhaps they have learnt from the riots
in Nigeria
provoked by a lunar eclipse last January, when rampaging Islamic
gangs burnt
down more than 40 hotels and drinking houses in the city of
Maiduguri,
blaming the eclipse on sinners and drinkers.
It is common in the educated west to think that such a
superstitious
response is the sign of a primitive people, and that superior
scientific
knowledge might lead to an advantage being gained. Most such
scenarios,
however, occur in fiction rather than fact.
It happens that, rather than disadvantage the natives, a previous
eclipse
seen in southern Africa led to the greatest disaster in British
military
history. A slightly misleading view of it has entered the popular
mind
through the 1960s movie Zulu (starring Michael Caine and Stanley
Baker).
On January 22, 1879, the Battle of Isandlwana (in the province of
South
Africa now known as KwaZulu Natal) led to the death of 1,329 out
of about
1,700 men on the British side. Of the Zulu army of around 20,000
warriors,
or impis, about three thousand were killed.
They had surrounded the redcoats at the rocky outcrop known as
Isandlwana,
using their favoured Buffalo Head formation, the main army being
the head of the buffalo
while the two horns encircled opponents. The few British soldiers
to escape
hastened to the Swedish mission station at Rorke's Drift, where
just over a
hundred troops held off a subsequent attack by several thousand
impis.
After the defence of Rorke's Drift more Victoria Crosses were
awarded than
for any other battle in history, perhaps as an attempt by
officialdom to
partially cover up the disaster at Isandlwana.
This date in history is also marked as the day of an eclipse, and
that is
not a coincidence. As an astronomer I can easily sit down and
calculate the
circumstances. It was an annular solar eclipse, meaning that a
bright ring
of the Sun's surface would still have been visible even if you
had been
positioned on the central line, which cut across Africa. At the
battlefield
site it was only a partial eclipse, with two-thirds of the solar
disk being
covered at the eclipse's peak. But that was enough.
The Africans remembered the day in question as the Day of the
Dead Moon. The
massive Zulu army had been mustered for an engagement, but
because of a
superstition about the state of the moon, their leaders had not
intended to
fight that day. This belief said there are evil spirits in the
air when the
moon disappears for a few days each month near conjunction (when
it is near
the Sun in the sky and so is lost in the solar glare). As a
consequence,
they were waiting until after the new moon re-appeared as a
slender crescent
a couple of evenings later.
Late on the morning of January 22, however, a patrol of British
cavalry rode
over a bluff and found the Zulu army hidden in a shallow valley.
This should
have given the main British contingent a chance to form a
suitable defensive
position, but celestial events overtook them.
The Zulus, unsettled by their discovery, were astonished to see
an eclipse
begin soon after 1pm, as if it were a divine sign. The
significance here is
not that it hid part of the Sun, but that it made visible, as a
silhouette,
part of the moon. The Zulu initially did not want to fight
because of the
bad portent represented by the moon not being seen at that time
in the
month. The solar eclipse, paradoxically, made the moon obvious in
the sky,
giving great heart to the impis.
At the location of the battlefield the eclipse reached a maximum
at 2.30pm,
by which time the massacre was all but complete. It was still in
progress as
they stormed onwards to begin the assault on Rorke's Drift at
about 3pm. It
has long been a mystery why the Zulu did not resume their attack
on the
mission the following morning.
I would suggest that it is easy to understand in the context of
the eclipse.
The next day, the Moon could no longer be seen, the eclipse
having been
completed at about 4pm the preceding afternoon, and that was
interpreted by
the Zulu as a sign that they should cease, pending the sighting
of the new
moon. This gave the British survivors the breathing space they
needed. What
could the British commanders have done differently?
It seems clear that events would have been quite different if
there had been
two scientists available to the generals. One would be an
astronomer, to
tell them that an eclipse was imminent, and another an
anthropologist, to
inform them how the Zulu might react. That is projecting modern
values on a
wartime disaster from more than a century ago, but in describing
events on
that dark day, the role the eclipse played is often neglected.
Which brings us back to the total solar eclipse for southern
Africa today.
By chance, there happens to be another in the region in December
next year,
and it even crosses again the Angolan town of Lobito, whose
hoteliers must
be delighted. I plan to watch that one, though, after it has
crossed the
Indian Ocean, just before sunset in South Australia.
* Duncan Steel is a physicist at the University of Salford. His
book
Eclipse (Headline) explains the significance of eclipses in
history.
Copyright Guardian Newspapers Limited
============
(2) LIFT OFF FOR ROSETTA AT LE BOURGET
From ESA News, 20 June 2001
http://sci.esa.int/content/news/index.cfm?aid=1&cid=1&oid=27505
The January 2003 launch of ESA's Rosetta comet chaser by an
Ariane 5 rocket
was confirmed on Tuesday, 19 June, at the Paris Air Show. Ariane
5 is one of
the few rockets in the world with the payload lift capability
required to
send the three tonne Rosetta spacecraft towards the distant
comet.
The signatories at the official ceremony marking the completion
of the
Rosetta launch services contract negotiations were the ESA
Science Director,
Professor David Southwood, and Arianespace Chairman and CEO,
Jean-Marie
Luton.
Ariane 5 is one of the few rockets in the world with the payload
lift
capability required to send the three tonne Rosetta spacecraft
towards the
distant comet.
"The 2003 launch will mark the first time an Ariane 5 has
launched a
spacecraft beyond Earth orbit," said Dr John Ellwood, the
ESA project
manager for Rosetta.
Other key factors were the willingness of Arianespace to do
everything
possible to ensure that the launch will take place within the
three-week
launch window and the launcher's ability to perform an extended
coast phase
with its EPS upper stage.
After launch from Kourou spaceport in French Guiana, the EPS
stage and its
Rosetta payload will remain in a 4000 km x 200 km coast orbit for
just under
two hours. Prior to reaching perigee (the closest point to the
Earth), the
upper stage will be ignited, injecting Rosetta into the required
Earth
escape trajectory towards Mars.
"We're very happy to be able to use this extended coast
phase capability of
Ariane 5, which is critical to the Rosetta mission," said
Professor
Southwood.
Rosetta is one of the Cornerstones in ESA's long-term scientific
programme.
Its objective is to carry out the most intensive and detailed
studies ever
made of a comet, and hence hopefully unlock the mystery of how
life evolved
on Earth. The small cosmic snowballs we know as comets are
generally
regarded as the most primitive objects in the Solar System, the
building
blocks from which the Earth and other planets were formed some
4.6 billion
years ago.
During its eight-year odyssey to Comet 46P/Wirtanen, Rosetta will
swing by
Mars once and Earth twice, using their gravity to provide the
energy needed
for its voyage into deep space. The extended trek will also
include flybys
of two unusual asteroids, Siwa and Otawara.
Rosetta will eventually rendezvous with Comet 46P/Wirtanen in
November 2011.
While the Rosetta Orbiter's payload of scientific instruments
studies the
comet from close range - with the closest observations made from
a distance
of about 1 km - a small lander will be released onto the comet's
surface to
make direct observations of the solid nucleus.
The Orbiter's comet reconnaissance mission will continue for
nearly two
years, during which it will monitor the dramatic changes that
take place as
the nucleus begins to vapourise in the warmth of the Sun.
=========
(3) ARIANE TO LAUNCH ROSETTA EXPLORATION SATELLITE
From Yahoo News, 19 June 2001
http://biz.yahoo.com/rf/010619/0574212.html
LE BOURGET, France, June 19 (Reuters) - Western Europe's
Arianespace launch
company said on Tuesday it had won a contract to launch the
Rosetta
interplanetary exploration satellite for the European Space
Agency (ESA).
Rosetta will be launched in early 2003 aboard an Ariane-5 rocket
from
Ariane's launch centre in French Guiana on South America's
northeast coast.
Rosetta's eight year mission will be to rendezvous with the comet
46P/Wirtanen.
``Rosetta will swing by the earth twice, and Mars once, using
their gravity
to provide the energy needed for its long voyage and send it on
the right
path,'' Arianespace said in a statement released after a signing
ceremony at
the Paris air show.
``During its eight year voyage, Rosetta will perform flybys of
two
asteroids, Otawara and Siwa,'' it said.
John Ellwood, Rosetta project manager for ESA, said the final
cost of the
Rosetta programme, launch, satellite, payload and ground centres,
could
approach $1 billion.
The satellite will be built by Italy's Alenia Spazia, a division
of
Finmeccanica and will weigh three tonnes at launch.
Also on Tuesday, Arianespace signed a letter of intent with
London-based
satellite operator Inmarsat for the launch in 2003/2004 of an
Inmarsat-4
satellite for the organisation's global satellite network.
The contract brings Arianespace's backlog to 41 firm satellite
launch orders
worth over $3 billion.
Earlier on Tuesday International Launch Services (ILS),
Arianespace's
arch-rival, also signed a letter of intent for the launch of
another
Inmarsat-4 satellite. Inmarsat officials said the status of the
ILS's
contract was more advanced than Arianespace's but expected both
to become
firm orders in the next several weeks.
Copyright © 2001 Yahoo! Inc.
==========
(4) NASA'S TERRA SATELLITE CAPTURES A WORLD OF SUNLIGHT AND HEAT
From Andrew Yee <ayee@nova.astro.utoronto.ca>
David E. Steitz
Headquarters, Washington,
DC
June 21, 2001
(Phone: 202/358-1730)
Chris Rink
Langley Research Center, Hampton, VA
(Phone: 757/864-6786)
RELEASE: 01-123
NASA'S TERRA SATELLITE CAPTURES A WORLD OF SUNLIGHT AND HEAT
The beginning of summer is an annual reminder that our world is
driven by
sunlight, and new Terra satellite measurements show just how much
the Sun
influences the Earth's climate system.
The first observations, from March 2000 to May 2001, of the
Clouds and the
Earth's Radiant Energy System (CERES) instruments aboard Terra
are the most
accurate global radiation or energy measurements ever and include
the first
complete year of such essential data since 1987. These new CERES
data,
available at NASA Langley Research Center's Atmospheric Sciences
Data
Center, Hampton, VA, capture incoming and outgoing energy over
the whole
planet and provide new insights into climate change.
"The new data will play a critical role in narrowing the
uncertainties in
predictions of future climate change, especially for the
undefined role of
the Earth's cloudiness," said Bruce Wielicki, a CERES
principal investigator
at Langley, where the CERES mission is managed.
For scientists to understand climate, they must also determine
what drives
the changes within the Earth's radiation balance. CERES measured
some of
these changes over the last year, producing new images that
represent data
collected twice per day over the whole planet. CERES captured the
May 2001
heat wave that swept across the southwestern United States.
Temperatures
soared to as high as 109 F in parts of California, setting new
records.
The recent U.S. heat wave is only one example of outgoing energy
from the
Earth. Everything, from an individual person to the Earth as a
whole, emits
energy. As Earth absorbs solar energy, it warms up. To keep our
planet at an
overall hospitable temperature, the Earth must emit some of this
warmth, or
energy, into space.
Earth's outgoing energy has two components: thermal radiation
emitted by the
Earth's surface and atmosphere, as in last month's heat wave, and
solar
radiation reflected back to deep space by the oceans, lands,
aerosols and
clouds.
It is the balance, which scientists refer to as the Earth's
"radiation
budget," between the incoming energy from the Sun and
outgoing energy back
to space that determines Earth's temperature and climate. This
balance is
controlled by both natural and human-induced changes, giving
scientists a
wide range of questions to study.
Even though CERES has the ability to capture short-term changes
like the
recent heat wave, "the real power of the CERES data will
come from the
analysis that integrates CERES' highly accurate measurement of
energy with
other measurements from Terra of the individual components of the
climate
system," Wielicki said.
The international CERES team is now completing an integration of
satellite
data over the entire planet from space-borne instruments on seven
different
spacecraft to test the accuracy of global climate models, a task
never
before attempted. This will allow a new picture of the energy
balance from
the top of the atmosphere, all the way down to the surface of the
Earth.
Analyzing how well climate models compare to CERES will tell the
researchers
which areas most closely illustrate the Earth's natural
responses.
"CERES Terra is providing an unprecedented observational
basis, at just the
time when major progress in understanding our environment by
theory and
climate modeling is taking place," said Leo Donner, a CERES
science team
member and climate modeler at the National Oceanic and
Atmospheric
Administration's Geophysical Fluid Dynamics Laboratory, Princeton
University, Princeton, NJ.
The Terra spacecraft is part of NASA's Earth Science Enterprise,
a long-term
research effort being conducted to determine how human-induced
and natural
changes affect our global environment.
Additional information is available on the Internet at:
http://asd-www.larc.nasa.gov/ceres/ASDceres.html
http://visibleearth.nasa.gov/Sensors/Terra/CERES.html
===========
(5) UK SPACE CENTRE PREPARES FOR LAUNCH
From the BBC News Online, 19 June 2001
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1394000/1394524.stm
By BBC News Online science editor Dr David Whitehouse
The next best thing to going into space is soon to be available
to the
public in Britain when the National Space Science Centre (NSSC)
opens its
doors on 30 June.
Situated in a space-age building in Leicester, the NSSC offers
one of the
most remarkable days out anywhere on the planet.
Four years in the making, it contains five main exhibit areas
surrounding a
state-of-the-art planetarium that produces out-of-this-world
special
effects.
BBC News Online was given an exclusive preview of the centre,
during the
final stages of preparation.
Space place
The NSSC was born in 1995 when a group of enthusiasts bemoaned
the fact that
there were few places to go in Britain where the excitement and
drama of
spaceflight was available to the public.
In 1997 the proposal for a purpose-built space centre received
£26m from the
National Lottery allowing the idea to get off the ground, so to
speak.
"Then the hunt was on," says Alexandra Barnett,
Programmes Director of the
NSSC. "We wanted to make it the most amazing space place in
Europe and we
began searching the world for rockets, satellites and space
capsules."
A sign of the successful search dominates the entrance hall: a
complete
Russian Soyuz space capsule, identical to the ones in use today.
"Isn't it magnificent?" she asks. "It had been
lying in the corner of a car
park in Russia for ages before we heard of it. Now it's one of
only two
Soyuz capsules in the West, and look, [she points to various
devices jutting
out from the capsule], it has all the components it needs to go
into orbit."
"Space is such an exciting subject," says Alexandra
Barnett. "We have to
live up to that."
By the looks of the centre, in its final stages of construction
when I saw
it, it will do just that.
Its five main galleries contain innovative displays and
interactive exhibits
that show the visitor what it would be like to go into outer
space and what
the Universe is like beyond that.
The centrepiece of the exhibits is the huge, six-storey, tower
that contains
two rockets. Visitors can stand beneath their nozzles and peer up
into the
rocket motors, or take an elevator along them looking at the fuel
tanks, the
electronics bays and the docking collars between stages.
'Good day out'
There is a full-scale walk-through of part of the International
Space
Station as well as a sit-in Mercury capsule where you can go
through a
simulated launch and you can take the test: "Have you got
what it takes to
be an astronaut?"
I ask Alexandra if she has taken it. "Yes, but I don't think
I'll make an
astronaut just yet," she laughs.
But it is not all rockets and satellites by any means. The
"Space
Connections Trail" is a surprising collection of different
items that are
connected, in some way, to space.
It ranges from a crisp packet (metal deposited on plastic, a
technology
developed for satellites) to a sports bra (designed using
engineering
techniques developed to measure stresses and strains on rockets).
There is also a section called "Orbiting Earth" that
looks at how we use
space in our everyday lives - telecommunications, broadcasting
and
navigation.
"We even have a weather forecasting studio for anyone who
wants to try their
hand at that," says Alexandra Barnett.
"We really can take you on a trip to the edge of the
Universe and back
again. It will be a pretty good day out."
Copyright 2001, BBC
========
(6) EUROPEAN ASTRONOMY IN THE 20TH CENTURY
From Wolfgang R. Dick <wdi@POTSDAM.IFAG.DE>
Special Colloquium on the History of Astronomy "European
Astronomy in the 20th Century"
in the framework of the Joint European and National Astronomical
Meeting for 2001.
J E N A M - 2001
10th European and 75th Annual Assembly of Astronomische
Gesellschaft
September 10-14, 2001, Munich, Germany
Second announcement
The European meeting of astronomers to be held in September 2001
in Munich
will give the opportunity to review the development of astronomy
in Europe
during the last century. Emphasis will be made on the evolution
of ideas,
instruments and scientific results, although the history of
institutions and
biographies of astronomers may also be considered.
For detailed information on the colloquium, please visit the Web
page
http://www.gamma.mpe-garching.mpg.de/~hcs/JENAM2001MS/
or ask for the First Announcement. [Distributed through HASTRO-L
on 10 April
2001. Published in ENHA No. 45, April 11, 2001.]
Scientific Organizing Committee - SOC:
Dr. Wolfgang R. Dick, Potsdam, Germany, e-mail: wdi@potsdam.ifag.de
Dr. Izold Pustylnik, Toravere/Tartu, Estonia, e-mail: izold@aai.ee
Dr. Helmut Steinle, Garching, Germany, e-mail: hcs@mpe.mpg.de
Dr. Christiaan Sterken, Brussels, Belgium, e-mail: csterken@vub.ac.be
Local Organizing Committee - LOC:
Dr. Helmut Steinle
Contact address:
Dr. Helmut Steinle
Max-Planck-Institut fuer extraterrestrische Physik
Postfach 1312
85741 Garching
Germany
E-mail : hcs@mpe.mpg.de
WWW : http://www.mpe.mpg.de/hcs/
Phone : (49) 89 30000 3374
Fax : (49) 89 30000 3569
Location: Campus of Ludwig-Maximilians-University Munich, located
well in
the city centre of Munich.
Time: Friday, September 14: 14.00-15.30 and 16.00-17.30
Saturday, September 15: 9.00-10.30
and 11.00-12.30
Symposium Language
English and German are working languagues of the colloquium.
Usage of other
European languagues is welcome (unfortunately, the hosts are
unable to
provide simultaneous translation). When not using English for
your oral
paper or poster please present some help for the audiance to
understand what
your paper is about: written English summary, transparencies in
English, or
similar.
Call for Papers:
Please see the Web site or the First Announcement for detailed
information.
Please note the deadlines for submitting abstracts:
Oral Papers: July 1, 2001
Poster Papers: July 13, 2001
The program of the meeting will be announced at the Web site by
the end of
July.
Registration and Registration Fees:
For participants of the general JENAM-2001 conference who also
want to
attend this Special Colloquium, please see the JENAM-2001 web
site
http://www.mpa-garching.mpg.de/english/conferences/jenam01/
Registration fees are:
Members of AG and EAS: 150.00 DM
Students:
80.00 DM
Other:
180.00 DM
Accompanying Persons: 60.00 DM
Reduced fee for Special Colloquium only participants (who will
arrive on
Friday noon and will not take part in other parts of JENAM-2001):
50.00 DM
Participants for the Special Colloquium only:
* do not register at the JENAM-2001 conference
directly
* send the Registration Form (see below) to
the LOC, or register
on-line at
http://www.gamma.mpe-garching.mpg.de/~hcs/JENAM2001MS/registration.html
Deadline: June 28 !
* make your own hotel reservations soon (see
Web site for
recommendations).
Events:
Friday evening: Get-together at a
restaurant
If interest exists, we will try to organize a tour on Saturday
(September
15) afternooon to one of the places of interest for historians of
astronomy
which are in Munich or its surroundings. Possible places are:
European Southern Observatory
headquarters (ESO)
Max-Planck-Institut fuer
extraterrestrische Physik (MPE)
Institute of Astronomy and Astrophysics
at the Ludwig-Maximilian
University Munich (USM)
Deutsches Museum
Benediktbeuern and J. Fraunhofer's glass
production site
Please indicate any preferences in the registration form!
See on-line registration form at
http://www.gamma.mpe-garching.mpg.de/~hcs/JENAM2001MS/registration.html)
============================
* LETTERS TO THE MODERATOR *
============================
(7) ASTEROIDS RATHER THAN COMETS
From Richard Taylor <richard.taylor3@virgin.net>
Richard L. S. Taylor - Probability Research Group
e-mail: probability.rgroup@virgin.net
and richard.taylor3@virgin.net
Dear Benny,
In his comments on Michael Paine's opening discussion about
"the ejection
of surface rocks from Mars during impacts by large
asteroids", Duncan Steel
points out that the feasibility of material being thrown
off Mars, or
indeed off any other planetary target, depends critically upon
the impact
speed. He goes on to cite the result of an analysis he performed
using a
sample of over 600 observed Mars-crossing asteroids from which he
calculated
a mean impact speed of 9.3 km/sec, with less than five percent of
the
impacts at greater than 20 km/sec and rather less than one
percent occurring
at greater than 30 km/sec. Using the relation given by Melosh
(H.J. Melosh,
"The rocky road to panspermia", Nature, volume 332,
pp.687-688, 1988) Steel
suggests that an impact speed in excess of 20 km/sec is necessary
to achieve
any substantial ejection from Mars. Duncan then goes on to argue
that only
comets have Mars-impact velocities capable of producing a
significant
quantity of Earth-crossing ejecta.
It is important, however, to clarify just what is meant by a
'substantial
ejection' from Mars. Do we speak in terms of total mass, or the
number of
high velocity spallation fragments, generated by the impact.
These are quite
distinct aspects of the collision process. In his monograph
'Impact
Cratering - A Geologic Process' OUP (1989) pp72 - 74 et
seq. Melosh
discusses the high speed ejecta that is produced by spallation
and although
low in terms of total mass spallation fragments fairly typically
attain
velocities twice that of the impactor. As the escape velocity of
Mars is
5km/sec Duncan Steel's calculated mean asteroid velocity of
~9km/s could
produce spallation plates - that then fragment through the action
of elastic
forces - with velocities of ~4 times that of Mars escape. As
spallation
fragments come from at or near the target's surface they are
ejected in the
very early stage of the formation of the impact crater. Because
of this they
are generally only lightly shocked and this may allow organic
materials, or
living cells, to survive far more readily than would be the case
for heavily
shocked material produced by the far higher cometary impact
velocities.
This suggests that asteroid collisions will be quite capable of
getting
low-mass high velocity fragments off Mars and into Earth-crossing
orbits.
The question is whether or not any of these small fragments can
survive the
descent through Earth's atmosphere and conserve any living
Mars-bugs.
Richard Taylor
===========
(8) TR/J EXTINCTION BOUNDARY
From Hermann Burchard <burchar@mail.math.okstate.edu>
Dear Benny,
here below is an abstract from NATURE concerning recently
improved quantum
mechanical models for seismic tomography of the Earth's mantle.
This
probably bears on cosmogenic impact generation of mantle hotspots
although
it is unclear exactly how, at least without having read the full
article.
Regards,
Hermann G.W. Burchard
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - -
nature 21 June 2001
Letters to Nature
Nature 411, 934 - 937 (2001) © Macmillan Publishers Ltd.
The elastic constants of MgSiO3 perovskite at pressures and
temperatures of
the Earth's mantle
ARTEM R. OGANOV, JOHN P. BRODHOLT & G. DAVID PRICE
Department of Geological Sciences, University College London,
Gower Street,
London WC1E 6BT, UK
Correspondence and requests for materials should be addressed to
A.R.O.
(e-mail: a.oganov@ucl.ac.uk).
The temperature anomalies in the Earth's mantle associated with
thermal
convection can be inferred from seismic tomography, provided that
the
elastic properties of mantle minerals are known as a function of
temperature
at mantle pressures. At present, however, such information is
difficult to
obtain directly through laboratory experiments. We have therefore
taken
advantage of recent advances in computer technology, and have
performed
finite-temperature ab initio molecular dynamics simulations of
the elastic
properties of MgSiO3 perovskite, the major mineral of the lower
mantle, at
relevant thermodynamic conditions. When combined with the results
from
tomographic images of the mantle, our results indicate that the
lower mantle
is either significantly anelastic or compositionally
heterogeneous on large
scales. We found the temperature contrast between the coldest and
hottest
regions of the mantle, at a given depth, to be about 800 K at
1,000 km,
1,500 K at 2,000 km, and possibly over 2,000 K at the core-mantle
boundary.
Macmillan Magazines Nature © Macmillan Publishers Ltd 2001
Registered No.
785998 England.
=============
(9) SPACE PARASOL
From John Youles <j.youles@ntlworld.com>
Dear Dr Peiser,
May I comment on Stephen Ashworth's excellent idea of a sunshield
to protect
us from excess solar radiation.
I question the idea of positioning it at a Lagrange point on the
Moon's
orbit. I would have thought that the shield would have to have to
be the
same diameter as the Moon to be as effective as a solar eclipse
which would
occur just as infrequently.
I wonder if we could put a number of "space clouds" in
relatively low Earth
orbit. I envisage them as being rather like large balloons,
reflecting solar
radiation away from the Earth. If they were large enough the
effect would be
similar to a solar eclipse. Their number could be varied as
needed to
increase or decrease the cooling effect.
Yours sincerely,
John Youles
Beckenham, Kent, England, UK
=============
(10) REFRESHING SKEPTICISM
From James Perry <AJDPerry@aol.com>
Dear Benny,
Just so you know, I very much like the format and content of the
CCNet list
right now. I like the way you have segregated the climate change
issues onto
separate mailings, and I think the frequency of the
climate-related e-mails
is about right (I don't belong to any other climate-related
lists). The
emphasis on skepticism is refreshing given that the non-skeptical
view can
be
found anywhere/everywhere else.
Sincerely,
James Perry
============
(11) SHAPING PUBLIC ATTITUTES TO TECHNOLOGY & INDUSTRIAL
PROGRESS
From Stephen Ashworth <sa@astronist.demon.co.uk>
Dear Dr Peiser,
With reference to your comment on 20 June 2001 --
> MODERATOR'S NOTE: Dear Charles Petit, I sympathise
with your lament. I also
> wish I could spend less time on this whole issue.
Nevertheless, the Global
> Warming controversy has turned into one of the most
heated scientific
> debates which, in any case, will have significant
repercussions for the
> technological evolution and economic development of
our planet in the next
> century. [. . .] BJP
I thoroughly applaud your position.
The Global Warming controversy is shaping broad public attitudes
to
technology and industrial progress, and therefore also public
attitudes to
whether humanity can or even should attempt to avert large-scale
catastrophes. It is shaping attitudes about whether we live in a
dynamic
world in which science and technology are a vital tool for
survival, or a
god-given static world which will leave us alone if we leave it
alone.
Many CCNet subscribers are no doubt aware of the Equinox
documentary
broadcast on the UK terrestrial channel Channel 4 last Sunday (17
June),
entitled "The Day the Oceans Boiled" (with reference to
the methane hydrates
on the sea floor, not the seawater itself).
This programme investigated research whose findings were as
follows: (1)
that the Amazon rain forest is currently soaking up a large
proportion of
the carbon dioxide emitted by industrial activities, (2) that a
small amount
of climatic warming could be expected to lengthen the dry season
in the
Amazon basin by sufficient to cause the Amazon rain forest to die
out and be
replaced by grassland, (3) that such a change in vegetation would
create a
sudden release of large amounts of carbon compounds back into the
atmosphere
as the trees decayed, (4) that this would cause a further major
step up in
global warming which in turn could warm the seas sufficiently to
release
large amounts of methane from methane hydrates on the sea bed,
and
(5) that the result would be global warming well into double
figures of
degrees centigrade sometime around the year 2100. Finally (6),
the programme
connected this scenario with research into a climatic catastrophe
55 million
years ago which is believed to have followed a similar course,
though
without the initial stimulation of industrial pollution. We were
shown
temperature graphs with abrupt warming spikes, reconstructed from
analysis
of oceanic cores.
It was interesting to note that only scientists whose work was
consistent
with the above sequence of events were interviewed. Sceptics were
completely
absent and (by implication) did not exist. The narrator was
clearly a
graduate from the school of funereal voices; the music drawn from
a symphony
portraying the end of the world. The plant cover of the rest of
the world
was not mentioned; by implication it was either small in
comparison with
that of the Amazon basin, or ineffective in absorbing carbon
dioxide. The
status of carbon dioxide as a powerful greenhouse gas with a
direct effect
on global temperatures was unquestioned (the programme did not
even mention
water vapour). Alternative scenarios, whether involving natural
negative
feedback loops or technological progress, were completely
ignored, and if
viewers wished to draw the conclusion that industrial
civilisation was well
on course for extinction, no obstacles were placed in their
way. The Sunday
Times TV critic caught the tone of the programme when he
commented: "A
frightening film, which someone should force George W Bush to
watch."
Yours sincerely,
Stephen Ashworth
Oxford, UK
Fellow of the British Interplanetary Society
Webmaster, Space Age Associates
21 June 2001
===========
(12) TERRESTRIAL EVIDENCE OF A NUCLEAR CATASTROPHE IN PALEOINDIAN
TIMES?
From Bob Kobres <bkobres@uga.edu>
In regard to the possible influence of a nearby supernova (CCNet
80/2001 -
19 June 2001), there is a recent paper in which the authors show
evidence of
neutron bombardment on chert artifacts. This event is
reckoned to have
occurred around 12,500 years ago and, the authors contend, was
causal of the
megafauna extinction, which took place on the North American
continent
following this time period.
From: THE MAMMOTH TRUMPET (March 2001)
TERRESTRIAL EVIDENCE OF A NUCLEAR CATASTROPHE IN PALEOINDIAN
TIMES
by Richard B. Firestone, Lawrence Berkeley National Laboratory,
and William
Topping, Consultant, Baldwin, Michigan
THE PALEOINDIAN OCCUPATION of North America, theoretically the
point of
entry of the first people to the Americas, is traditionally
assumed to have
occurred within a short time span beginning at about 12,000 yr
B.P. This is
inconsistent with much older South American dates of around
32,000 yr B.P.1
and the similarity of the Paleoindian toolkit to Mousterian
traditions that
disappeared about 30,000 years ago.2 A pattern of unusually young
radiocarbon dates in the Northeast has been noted by Bonnichsen
and Will.3,4
Our research indicates that the entire Great Lakes region (and
beyond) was
subjected to particle bombardment and a catastrophic nuclear
irradiation
that produced secondary thermal neutrons from cosmic ray
interactions. The
neutrons produced unusually large quantities of 239 Pu and
substantially
altered the natural uranium abundance ratios ( 235 U/238 U) in
artifacts and
in other exposed materials including cherts, sediments, and the
entire
landscape. These neutrons necessarily transmuted residual
nitrogen ( 14 N)
in the dated charcoals to radiocarbon, thus explaining anomalous
dates.
The complete paper is available here:
http://abob.libs.uga.edu/bobk/nuclear.html
Topping and Firestone may have found conclusive evidence for a
supernova,
neutrons are not particularly easy to produce, however I've a
hunch that it
might be possible for neutrons to be generated during high-energy
events
that involve materials rich in deuterium, such as comet nuclei.
It's still
quite a mystery as to exactly what transpires in events that we
cannot
experimentally recreate so I've asked that most widely know
detective to do
a bit of investigating. ;^)
http://abob.libs.uga.edu/bobk/caseof.html
Later.
bobk
Bob Kobres
bkobres@uga.edu
http://abob.libs.uga.edu/bobk
706-542-0583
Main Library
University of Georgia
Athens, GA 30602
==============
(13) AND FINALLY: AFRICA ON RIOT ALERT OVER FIRST ECLIPSE OF
MILLENNIUM
From The Independent, 21 June 2001
http://news.independent.co.uk/world/africa/story.jsp?story=79314
By James Palmer
21 June 2001
Thousands of tourists will flock to the states of southern Africa
today for
the first solar eclipse of the millennium, prompting fears that
ignorance of
the event could lead to rioting and blindness.
The eclipse begins in the South Atlantic and ends in the Indian
Ocean and
will be seen in Angola, Zimbabwe, South Africa, Mozambique and
Madagascar.
Police forces in some countries are on alert for riots and mass
panic during
"totality" when the Moon completely covers the Sun
at 2.15pm BST.
Some southern Africans believe eclipses are portents of doom.
Witch doctors
in Madagascar have been warning people to stay indoors.
The last total solar eclipse seen in southern Africa was in 1835,
when the
ethnic Ngonis, escaping from the Mfecane wars in South Africa
were about to
cross the Zambezi river. They retreated, thinking that the
eclipse was a bad
omen. The Ngonis will hold a commemoration today in the Luangwa
valley, one
of the main eclipse view sites in Zambia.
Zambia, which is expecting the lion's share of tourists, has
declared a
public holiday. The country expects a $15m windfall from eclipse
visitors.
Hotels in Lusaka and towns that dot the eclipse path are booked
beyond
capacity. .
Professor Jay Pasachoff of Williams College in Massach-usetts
said:
"Watching the eclipse is a unique phenomenon. It is the only
time Jupiter,
Venus and Mercury make a daytime appearance. It is a spectacle
like no
other."
Copyright 2001, The Independent
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