PLEASE NOTE:


*

CAMBRIDGE-CONFERENCE DIGEST, 23 March 1998
------------------------------------------

"Civilization exists by geologic consent,
subject to change without notice." Will Durant



(1) ASTEROID 1997 XF11 BRINGS OUT THE WORST IN MISANTHROPIST
    Benny J Peiser <b.j.peiser@livjm.ac.uk>

(2) COME ON DOWN, THAT ASTEROID
    Taki, The Sunday Times

(3) IMPACT AND SIGNIFICANCE OF THE XF11 SCARE
    David Morrison <dmorrison@mail.arc.nasa.gov>

(4) THE SKY MAY NOT BE FALLING AFTER ALL
    Pauline Arrillaga, The Associated Press

(5) NON-NUCLEAR STRATEGIES FOR DEFLECTING COMETS AND ASTEROIDS
    Paolo Farinella <paolof@keplero.dm.unipi.it> wrote:

(6) STONES FROM THE SKY: METEORITES OR HAIL
    Rob McNaught <RMN@AAOCBN3.AAO.GOV.AU>

(7) TINY TEETH SHED LIGHT ON ANCIENT COMET
    Simon Mansfield <simon@spacer.com>


==========================
(1) ASTEROID 1997 XF11 BRINGS OUT THE WORST IN MISANTHROPIST

From: Benny J Peiser <b.j.peiser@livjm.ac.uk>

Throughout the ages, one of the most unpleasant and depressing
biproducts of periods of hightened apocalyptic fears has been the
periodic burst of religious fanatisicm and political extremism.
Human history is laden with tragic examples of such episodes of
mass hysteria, religious persecution and political repression
persued by apocalyptic movements. In most cases, it is profound
anxiety and alarm which accompanies end-time fears and which can
trigger feelings of extreme aggression. Since this fury cannot be
directed against the perceived natural threat, it is often directed
against political or religious opponents.

Indeed, most of the world's apocalyptic faiths base their creed on the
notion that all of their enemies will be utterly destroyed by the
ultimate global catastrophe, leaving only true believers exclusively
unharmed. Political proto-fascists, on the other hand, hope that after
a purifying cataclysm, modern art and human rights, democracy and
freedom of speach, as well as racial and gender equality will vanish
for good. Such insane reactions to a real (or imagineray) threat
are, of course, pitiable and interesting from psychiatric
perspective. Yet whatever the psychological reasons for this
collective madness might be, the consequences and human costs of
apocalyptic policies have only been too disastrous in the past.

An archetypal exemplar of such apocalyptic irrationality appeared
in yesterday's THE SUNDAY TIMES. It is a sad exposition of the
cynical response by one of Britain’s most notorious misanthropists
and gossip-mongers, “Taki”. I hope you will forgive me for making
his provocative comments available on this list - but I thought
you might be interested to know that 1997 XF11 has also brought
out the worst in some tortured souls. God bless them.

Can you imagine what might have happened to poor Taki and his
fellow apocalyptics around the world if Eleanor Helin hadn't
discovered her 1990 films of asteroid 1997 XF11, thereby
thankfully defusing the crisis? And what if her observational data
and that of Jim Scotti had shown that 1997 XF11 were on an 
a c t u a l  collision course with Earth? 

I'm afraid that the many over-optimistic responses to asteroid
1997 XF11 are just as misplaced and extravagant. Such show of
enthusiasm, I believe, actually forms the other side of the coin of
apocalyptic overreaction. While I share David Morisson's hope (see
his comments below) that something good will come out of the 1997 XF11
affair, I cannot join him to marvel in the imagination of an one-mile
wide asteroid currently hurtling towards Earth on a collision course. I
am simply unable to share his conviction that such a doomsday scenario
at the present time  would have been "a wonderful thing", and I still
have my doubts whether the "nations of the Earth" would have reacted in
the rational and humanistic way David believes.

Whereas David appears somewhat disappointed at the prospect of XF11
missing us by 600.000 miles and thus sees "an opportunity lost", I
believe that the happy ending of the 1997 XF11 affair gives us vital
time (and that's what is most needed, after all) to prepare ourselves
psychologically, socially and technologically for any future case of
real emergency. The more time we've got, the greater the chances
are that we will eventually be able to deal with the NEO threat
effectively.

Benny J Peiser

=====================================
(2) COME ON DOWN, THAT ASTEROID

From: THE SUNDAY TIMES, 22 March 1998

By Taki

I did not rejoice at the news that Asteroid 1997 XF11 may not, after all,
land among us. I was, of course, relieved to know that harm is unlikely
to befall my children. Still, I thought the world might not be such a
bad place after a collision, certainly better than what it would be
like in 2028 without a crashing asteroid.

Consider the good things. All the architectural monstrosities would tumble.
No more Guggenheim in Bilbao, no more Lloyd’s, no more addition to the
Victoria & Albert. But the great buildings, erected on strong
foundations, would remain. St Paul’s would survive, as would the
Rockefeller Centre, as would the Brandenburg Gate.

Furthermore, because many people would have perished, there would be an
urgent need to replenish the human stock. Reproduction of the species
would take priority over almost everything else. Women would have their
hands full with the endeavours for which they have the greatest
aptitude. Women may be cleverer, stronger, healthier and in every way
superior to men; but when it comes down to it, it is babies that count.

Any feminist screeching that women should do men’s work would be taken to
a re-education camp to be taught how to subordinate herself to the
needs of humanity and find fulfilment in becoming a wife and a mother.

Whatever stands in the way of rebuilding civilisation would go. Producers
and directors of cretinous entertainment such as Hollywood would be out
of business. The tidal wave after impact would destroy the overpriced
mansions of El Lay, ditto Miami Beach. On the other hand, as a number
of movie stars - Leonardo DiCaprio, Brad Pitt, Kate Winslet, the divine
Helen Hunt - are physically fine human specimens, they would be of use
in the reproductive enterprise.

Hacks, too, would go. Not only would everybody be too busy scrounging and
fending for themselves, but the risk attendant upon whipping up envy
and resentment among the populace would be so great that “journalism”
would be severely curtailed.

The greatest threat would come from scavengers. Any noisy gathering of
youths would be assumed to be a conspiracy and would be dealt with
summarily. Skills would be valued. There would be no “diversity”
programmes to ensure that all races and genders are represented in
every activity. A physicist who is non-white but does not know how to
repair a broken pylon would not be much use.

Rock music would be out and classical music in. Partly that is because,
with everybody so near barbarity, uplift would be essential. Great art
and literature would be treasured. The purveyors of academic trash
would pass into oblivion. Sport would again be an opportunity for
people to compete in friendship, not enmity.

What a pity I shall not be here to enjoy the coming of the asteroid.
If it were sure to hit, I would take care of myself just to greet it.

(c) 1998 The Sunday Times

========================
(3) IMPACT AND SIGNIFICANCE OF THE XF11 SCARE

From: David Morrison <dmorrison@mail.arc.nasa.gov>

NEO News (3/20/98)
 
IMPACT AND SIGNIFICANCE OF THE XF11 SCARE
 
One of the most frequent questions I was asked at the annual NASA Lunar
and Planetary Conference this week in Houston was "Do you think the
XF11 affair was a net positive or negative for public interest in the
impact hazard (or for the future of Spaceguard)?"  After discussing
this with scientists and the press, I don't know the answer. On the
positive side, a lot more people now know about the impact hazard.  On
the negative, quite a few of them accuse the asteroid scientists of
crying wolf or of being unreliable sources of information. I do think
it is important that we not make the same mistakes again. Concerns have
been expressed by both NASA, which is the largest funding source for
NEO searches, and the International Astronomical Union, which is
responsible for the Minor Planet Center. I believe that everyone agrees
that in similar future cases. we should take more time to check the
orbit and look for other observations before any announcements are made
to the press.
 
The two leading US weekly newsmagazines, Time and Newsweek, both feature
the asteroid story in their current (March 23) issues, and both had the
time to present an integrated story (unlike the daily media, which were
whiplashed by the rapidly changing story last week).  It is interesting to
compare the treatments in Time and Newsweek.  The Time story, which at four
pages is almost as long as some of their cover stories, is a serious
discussion by Leon Jaroff, who has supported us in the past (and who
criticized the US government for canceling Clementine 2 last summer). 
The story quotes Jack Hills, Brian Marsden, Greg Canavan, Jim Scotti,
Eleanor Helin, Don Yeomans, Gene Shoemaker, Clark Chapman, Tom Gehrels,
Edward Teller, and David Morrison -- quite a comprehensive list of
American sources. The emphasis is almost entirely on the reality of the
impact threat, with strong implications that we should be paying more
attention (and spending more money). There are no recriminations over
the affair of last week, with the revised 2028 miss distance for XF11
attributed to new data, not to mistakes. Also, there is an editorial
elsewhere in the magazine that uses the asteroid issue for a humorous
essay suggesting that it might be good for the earth to wipe out most
of humanity and what we call civilization.
 
The Newsweek story is shorter and less serious in tone (but still a
substantial 3 pages long). It discusses more of the history of the
discovery and orbit for XF11 and less on the general impact hazard. It
also plays up the conflicts, for example quoting Yeomans in accusing
Marsden of "crying wolf". There are a few factual errors: (1) The
claim is made that an impact from an asteroid as large as Ida
(identified as 36 miles across) would send us back the stone age, when
in fact it would very nearly sterilize the entire planet in an
extinction as large as the Permian, 250 million years ago.  (2) It is
claimed that asteroids and comets "refuse to stay in their orbital
lane" implying that they erratically shift orbits, a common public
misperception. (3) Jay Melosh is misquoted concerning the depth of
penetration of a colliding mile-wide asteroid. (4) It identifies the
Tunguska projectile as a comet rather than as asteroid and says it
ignited the clothes on a man 60 miles away. (5) It says Clementine 2
was a NASA mission rather than Department of Defense. In spite of these
technical lapses, however, most of the Newsweek story is good, and it
clearly communicates the long-term impact threat just as does the story
in Time.
 
Judging by Time and Newsweek, as well as the coverage in the major US
dailies such as the Washington Post and the New York Times, the XF11
story was handled accurately and placed in its proper context of the
long-term threat of impacts.  This was certainly a plus for public
communication. Elsewhere, on local TV and talk radio, there was a
greater tendency to make fun of the story.  Some also characterized it
as "the IAU got it wrong, but NASA got it right". Many also suggested
that somehow this was tied to the release of the two films Deep Impact
and Armageddon, even suggesting that the astronomers were in the pay of
the films. I hope this sort of thing was not intended (or taken )
seriously, but who knows, considering how cynical much of the American
public is these days.
 
My favorite headline: KISS YOUR ASTEROID GOODBYE.
 
I have heard very little of how the story was presented by the non-US
press, or received by the public internationally.
 
And finally, a very interesting question raised to me by George
Wetherill: suppose the miss distance for XF11 had held or dropped, and
there really was a small but significant chance of an impact, with 30
years of warning. That could have been a wonderful thing, inspiring the
nations of the Earth to work together to save the planet and perhaps
also to devolop the technical infrastructure for economical commercial
spaceflight. Thus defending our planet could untimately have been a
turning point in human history -- and now an opportunity lost.
 
David Morrison

=====================
(4) THE SKY MAY NOT BE FALLING AFTER ALL

By PAULINE ARRILLAGA, The Associated Press
 
HOUSTON (March 19, 1998 8:12 p.m. EST http://www.nando.net) -- A week
after coming off like Chicken Little with a Ph.D., some astronomers
have resolved to make sure they're right the next time they announce
the sky might be falling.
 
At a meeting this week in Houston, 15 astronomers from around the
country agreed to form a committee that will use its combined expertise
to calculate the risks to Earth when an asteroid looks like a threat.
 
"This group would be charged with assessing the threat and reaching a
consensus and a clearer plan for defining the nature of the threat,"
said Donald Yeomans, a scientist with NASA's Jet Propulsion Laboratory.
 
"We don't cry wolf. If it's a real threat, the announcement will be
made and steps will be taken to mitigate the threat."

Last week, it appeared a group of astronomers, the International
Astronomical Union, had cried wolf when they issued an alert saying
that an asteroid would pass within 30,000 miles of Earth -- and might
even collide with it -- on Thursday, Oct. 26, 2028, around 1:30 p.m.
The next day, Yeomans -- citing new data -- said the asteroid would
pass no closer than 600,000 miles and had no chance whatsoever of
hitting the planet.
 
All parties seem to agree that the gaffe could have been avoided had
the International Astronomical Union and NASA communicated earlier.
 
"It's in our best interest to try to get harmonious again," said Brian
Marsden, the distinguished Harvard astronomer who made the IAU
calculations.
 
Marsden and Yeomans were among the astronomers who met Tuesday at
Houston and decided to form the peer review committee.
 
When an astronomer discovers that an asteroid could threaten the Earth,
the committee will review the data and do its own calculations to
determine how serious the threat is.
 
"Within a matter of a day or two, the situation will become far more
clear and it will either become a nonevent or some appropriate
announcement will be made -- but not until this committee's had a
chance to chew on it for a bit," Yeomans said.
 
The committee members have not yet been selected, but they are likely
to include both Marsden and Yeomans.
 
Marsden admitted the entire asteroid episode "left a nasty taste in my
mouth."
 
Marsden said he made his calculations based on all the data available
at the time. In Marsden's 40 years of tracking asteroids, the space
rock was the first with the potential of coming so close to the Earth.
He said he decided to make an announcement to try to obtain additional
data.
 
Eleanor Helin of the Jet Propulsion Laboratory immediately called
Marsden and said that based upon his data, she had found 1990
telescopic images of the asteroid that could be helpful.
 
Using those pictures and recent observations, Helin's group calculated
the asteroid's new position and forwarded the information to Marsden
and her colleague, Yeomans. Yeomans simply beat Marsden to the punch by
releasing the information, she said.
 
"I'm very disappointed in how this unfolded," Helin said. "It appears
that people are trying to pit (Marsden's group) against NASA and vice
versa when, really, we're all friends."
 
Copyright) 1998 Nando.net
Copyright) 1998 The Associated Press

============================
(5) NON-NUCLEAR STRATEGIES FOR DEFLECTING COMETS AND ASTEROIDS

From: Paolo Farinella <paolof@keplero.dm.unipi.it> wrote:

Benny,

in commenting about the 1997 XF11 saga, many people are assuming that
the only possible way to deflect a km-size Earth-threatening
asteroid/comet is using nuclear expolosives. It seems to me that there
are several plausible alternatives. This has been discussed in detail
by H.J. Melosh, I.V. Nemchinov ad Yu.I. Zetzer in their chapter
("Non-nuclear strategies for deflecting comets and asteroids", pp.
1111-1132) of the well known book "Hazards due to Comets and Asteroids"
(T. Gehrels, Ed., University of Arizona Press, Tucson, 1994). Note that
these non-nuclear alternatives do NOT include chemical explosives, but
are based on a variety of different techniques: kinetic-energy impacts,
mass drivers, solar sails, solar collectors to heat and blow off
surface material, laser or microwave energy beams used for the same
purpose.

Actually, I fully concur with the conclusion of Melosh and coauthors that:

"Although all of these [non-nuclear] approaches probably require more
development and technical skill than the use of a nuclear explosive, the
danger inherent in the mere existence of an arsenal of large nuclear
weapons makes the nuclear approach very questionable..."  and that

"...Inasmuch as nuclear weapon deflection systems are likely to offer more
hazard to the human race than the asteroids they are designed to deflect,
it seems logical to bend our energies to extending and refining the
current work on non-nuclear deflection systems".

Paolo Farinella

Paolo Farinella                  Tel. +39-50-844254
Dipartimento di Matematica       Fax  +39-50-844224 
Universita` di Pisa
Via F. Buonarroti 2              e-mail: paolof@dm.unipi.it
I-56127 Pisa, Italy              WWW:    http://adams.dm.unipi.it/~paolof
=========================================================================
(6) STONES FROM THE SKY: METEORITES OR HAIL

From:  Rob McNaught <RMN@AAOCBN3.AAO.GOV.AU>

"And it came to pass, as they fled from before Israel, and were going
down to Beth-horon, that the Lord cast down great stones from heaven
upon them unto Azekah, and they died. More died with hailstones than
they whom the children of Israel slew with the sword." 

I have no idea what the conventional explanation for this is, but there
is presumably the explanation that the cause WAS hailstones.  Death by
hail is common worldwide and every few decades some hundreds die in
large hailstorms.  There are many more stock deaths, often thousands at
a time. Hail up to grapefruit size is not uncommon.

Statistics of hail deaths in the US give an annual average of "fewer than 5"
during the period 1970-76 [1].  Undoubtedly hail deaths are minimised in
modern society by predictions of severe weather and access to suitable
shelter. However, there have been large numbers of outdoor workers
killed in individual hailstorms in Asia.

     1888 Northern India, 246 people killed by cricket-ball sized hail.
     Some were killed directly by the hail, but most died in the drifts
     or of exposure.[2]

     1932 China; 200 killed. [2]

     In the last decade, I am aware of incidents in Bangladesh and China
     where hundreds were killed in huge hailstorms.

Perhaps many historical sources do make the distinction between hail and
stones, but where stones are mentioned without reference to "fire from
the sky" or some clearly meteoric characteristic, I would suspect hail
to be a strong candidate. However there are some unfortunate
similarities between the two phenomena

     meteoric fireball    -     lightning
     sonic boom           -     thunder
     meteorites           -     hail

such that historical sources may not allow a researcher to distinguish
between them. Past studies that interpret one way or the other without
specific mention of the other possibility, would suggest they were unaware
of the other interpretation.

There is also the question of anomalous falls of large chunks of ice, many
predating the era of air travel.  But that is another story!

[1] "The Thunderstorm in Human Affairs" 2nd Ed (1983) Ed. E. Kessler.
[2] "Weather Force" J. Gribbin (1979) quoting the "Guinness Book of Weather
    Facts and Feats".

Rob McNaught
(rmn@aaocbn.aao.gov.au)

======================
(6) TINY TEETH SHED LIGHT ON ANCIENT COMET

From: Simon Mansfield <simon@spacer.com>

http://www.usgs.gov/public/press/public_affairs/press_releases/pr452m.html]

U.S. Department of the Interior
U.S. Geological Survey
Central Region Outreach Office
P.O. Box 25046, MS 150
Denver, CO 80225-0046

Contact: Heidi Koehler
Phone: (303) 236-5900 ext. 302   Fax: (303) 236-5882

News Release: Embargoed until 3/20/98

Tiny Teeth Shed Light on Ancient Comets

Minuscule fossil animal teeth, known as conodonts, indicate that a
370-million-year-old comet that slammed into Nevada could be as much
as five times larger than scientists initially suspected.

"From conodonts discovered in debris from the impact, I have re-calculated
the crater depth and size," said Charles A. Sandberg, geologist emeritus
with the U.S. Geological Survey in Denver. "The crater left by the ancient
Nevada comet is now interpreted to have been at least one mile deep and
45 miles wide. It is comparable in size to one that struck the Chesapeake
Bay area about 35 million years ago. On the basis of this comparison, the
Nevada comet could have been as large as three miles in diameter, much
larger than our initial calculation of one kilometer. It may have been part of
the first of a series of comet showers that led to a mass extinction of many
forms of life three million years later."

Startling new evidence provided by these conodonts on the depth of the
crater produced by the Alamo Impact, 130 miles north of Las Vegas, will
be presented at the North-Central Section meeting of the Geological
Society of America in Columbus, Ohio on Friday, March 20, by Sandberg
and his co-author Jared R. Morrow, USGS volunteer and instructor at the
University of Colorado.

Conodonts are the microscopic teeth of primitive, boneless, eel-like
animals. The shape of these animals is similar to that of modern hagfish,
best known from the fjords of Norway. Conodont animals lived in many of
the world's oceans from the Cambrian through Triassic Periods of geologic
time (550 to 210 million years ago). The largest known conodont teeth,
found near the town of Alamo in southern Nevada, measure nearly a
half-inch in length, but most are not much larger than the head of a pin.

Evidence presented by Sandberg in October 1997 at the annual GSA
meeting in Salt Lake City showed that impact-related phenomena, such
as grains of shocked quartz and higher-than-usual levels of the element
iridium, occupied a circular area at least 120 miles in diameter, but the
size of the crater could not be determined then. Now, new conodont
evidence for its dimensions has been found in small blocks of fallout
debris from the impact crater. Iridium is an element found in asteroids and
comets but not common on Earth. Shocked quartz grains are produced by
the force of an impact on sandstone rocks.

This impact occurred during the Devonian Period of geologic time, 370
million years ago, when an ancestral Pacific Ocean covered most of
Nevada. The impact occurred offshore from a carbonate platform, very
much like the modern Australian Barrier Reef or the Bahamas Bank. Shock
waves from the impact and ensuing tsunami waves crashed against the
carbonate platform and coastline in a semicircular area 100 miles from
north to south. As the carbonate platform collapsed, blocks of rock
hundreds to thousands of feet across were torn from the seabed, twisted,
and transported seaward. As tsunamis of decreasing intensity
reverberated back and forth across the ocean basin, broken pieces of rock
and other ejecta from the impact were deposited over the carbonate
platform and high-water deposits were stranded in a semicircular band
along the coastline to the east.

The small blocks of impact-fallout debris recently found within the breccia
of large jagged blocks contain carbonate spherules formed from limestone
fragments that recrystallized within a superheated cloud, shocked quartz
grains, and bits and fragments of rocks blasted from the crater. Most
importantly, they also contain conodonts ejected from rocks that lay a mile
below the Devonian sea floor at the time of impact.

The timing of the Alamo Impact coincides with the demise of some Late
Devonian reefs in Belgium and Germany and with unusual breccias in
Germany and Austria. Earlier work by Sandberg and his co-authors has
already shown the possibility of two other times of impacts between that
of the Alamo Impact and the time of the Late Devonian mass extinction.

This presentation at the Geological Society of America section meeting is
part of a Pander (Conodont) Society Symposium, exploring the effects of
extraterrestrial impacts on major extinctions of ancient life. The symposium
will include talks by four USGS geologists and scientists from Austria,
Canada, England, Germany, and Sweden. The society is named after a
German-speaking paleontologist, Christian H. Pander, who first described
conodont microfossils in 1856. Since the middle of the 20th Century,
conodonts have become the most useful microfossil for dating marine
rocks, mainly because of their widespread distribution, fast rate of
evolution, and rapid recoveries from near-extinctions.

The keynote address by Hans-Peter Schonlaub, Director of the Austrian
Geological Survey, will stress the importance of conodonts in dating
impacts and extinctions during much of the time that life existed on Earth
and the scarcity of impact craters that are currently recognized and well
dated.

As the Nation's largest water, earth and biological science and civilian
mapping agency, the USGS works in cooperation with more than 2000
organizations across the country to provide reliable, impartial, scientific
information to resource managers, planners, and other customers. This
information is gathered in every state by USGS scientists to minimize the
loss of life and property from natural disasters, contribute to the sound
conservation, economic and physical development of the Nation's natural
resources, and enhance the quality of life by monitoring water, biological,
energy and mineral resources.

For additional information prior to March 17 contact:

Charles A. Sandberg, Geologist
sandberg@usgs.gov
Ph: 303.236.5763
Fax: 303.236.0459

Jared R. Morrow
morrow@ucsu.colorado.edu
Ph: 303.545.9983

For the October 1997 press release on the Alamo Impact, go to:
http://www.usgs.gov/public/press/public_affairs/press_releases/pr372m.html

---
Andrew Yee
ayee@nova.astro.utoronto.ca

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