PLEASE NOTE:


*
Date sent:        Thu, 04 Dec 1997 10:49:38 -0500 (EST)
From:             Benny J Peiser <B.J.PEISER@livjm.ac.uk
Subject:          CC Digest 4 December 1997
To:               cambridge-conference@livjm.ac.uk
Priority:         NORMAL

CAMBRIDGE-CONFERENCE DIGEST, 4 December 1997

(1) SCIENTISTS DESCRIBE ASTEROID'S ANCIENT OCEAN PLUNGE

(2) DIFFUSIVE CHAOS IN THE OUTER ASTEROID BELT

(3) COMPOSITIONAL PROPERTIES OF NEAR-EARTH ASTEROIDS

(4) THE NEAR RADIO SCIENCE INVESTIGATIONS

(5) AGAINST APOCALYPTIC THINKING

(6) MAGNETIC ANOMALY IN MANICOUAGAN METEORITE CRATER
 

======================================================================
(1) SCIENTISTS DESCRIBE ASTEROID'S ANCIENT OCEAN PLUNGE

27 November 1997

SYDNEY, Australia (AP) -- An asteroid that tumbled through space for
eons blasted into the sea off Antarctica more than 2 million years
ago with the force of "a cosmic bomb," a multinational team of
scientists said in a research paper published Wednesday.

Striking the Bellingshausen Sea with the explosive power of 100
billion tons of TNT, the asteroid Eltanin blew a column of water 5
kilometers (3 miles) high and punched a temporary "oceanic crater" in
the sea, according to the paper, which appeared in the British
science journal Nature.

The researchers estimate the asteroid was at least 1 kilometer
(six-tenths of a mile) and possibly up to 4 kilometers (2.5 miles) in
diameter.

The blast in the ocean did not leave a crater on the seabed, but a
similar strike on land would have left a hole 15 to 40 kilometers (9
to 25 miles) across.

'Devastating mega-tsunamis'

Eltanin, the only asteroid ever known to have hit water, triggered
waves 20 to 40 meters (65 to 130 feet) high, "devastating
mega-tsunamis" that swamped the coasts of South America and
Antarctica.

"The tsunami ... destroys enormous, large areas. ... In the Pacific
Rim there are signs of such things," one of the lead researchers,
Rainer Gersonde of the Alfred Wegener Institute for Polar and Marine
Research in Bremerhaven, Germany, told The Associated Press in a
telephone interview Wednesday.

Sediment spread up to 4,000 kilometers (2,500 miles) away and dust,
vapor and salts wafted around the world. Enough debris and hot vapors
were emitted to possibly damage the Earth's ozone layer, the
researchers said.

"The dust and vapor probably caused a major change in climate, but
whether that persisted or was for just a few years, we just don't
know," said Karsten Gohl, a geologist from Macquarie University in
Sydney who worked on the project.

There is no evidence that the climatic change caused the extinction
of any species.

New seismic and deep-sea surveys conducted in 1995 by the German
research ship Polarstern enabled the scientists to accurately date
the blast to the late Pliocene period, 2.15 million years ago,
and to gauge its effects.

An enigma solved?

The blast was well after the Northern Hemisphere's Ice Age began but
"close to one of the strongest cooling events in this time period,"
the researchers' paper said.

"It might be that this strong cooling was related to the impact,"
Gersonde told AP. The fallout from the blast may explain the "Sirius
enigma," the puzzle of why marine fossils are found high above sea
level in the Transantarctic Mountains.

The researchers believe fallout from the steam and vapor cloud
dropped micro-fossils directly on the mountains, an idea that
geologist Peter Barrett at Victoria University of Wellington, New
Zealand, called "reasonably plausible."

David Harwood at the University of Nebraska, an expert on the Sirius
fossils, conceded that the fallout theory "has potential" but said
some Sirius deposits do not fit the model. He is among those who feel
moving ice sheets may have scoured fossil deposits and redeposited
them in unexpected sites.

The Eltanin impact was a medium blast, as asteroids go.

About 65 million years ago, an asteroid about 10 kilometers (6 miles)
in diameter struck off Mexico's Yucatan Peninsula and is widely
believed to have killed off the dinosaurs by blotting out the sun
with the dust it kicked up.

But rocks far smaller than Eltanin can cause massive damage: A
meteorite only 45 meters (150 feet) across created Arizona's Meteor
Crater, 1,220 meters (4,000 feet) across and 180 meters
(600 feet) deep.

First known ocean strike

Eltanin is the only asteroid known to have struck the ocean, compared
with about 140 known to have hit land -- even though the Earth's
surface is 70 percent water, Jan Smits of the Research School of
Sedimentary Geology at Amsterdam's Vrije University noted in a
commentary on the research in Nature.

Besides Gersonde, in Germany, researchers on the project included
Frank Kyte at the Institute of Geophysics and Planetary Physics at
UCLA and scientists from the Department of Geology at the University
of Salamanca in Spain; Macquarie University's School of Earth
Sciences in Sydney; and the U.S. Naval Research Lab in Washington.

Eltanin is named for the U.S. research ship that brought up deep sea
samples in 1965 that later were found to contain iridium, an element
in asteroids.

======================================================================= (2)
N. Murray & M. Holman: Diffusive chaos in the outer asteroid belt
ASTRONOMICAL JOURNAL, 1997, Vol.114, No.3, pp.1246-1259

UNIVERSITY OF TORONTO, CANADIAN INSTITUTE OF THEORETICAL
ASTROPHYSICS, 60 ST GEORGE STREET, TORONTO, ON M5S 3H8,CANADA

We present an analytic theory of motion near resonances in the planar
elliptic restricted three-body problem. The theory predicts the
location and extent in semimajor axis and eccentricity (a,e) space of
the chaotic motion, the Lyapunov time, and the time for objects on
chaotic orbits to be removed from the system. The latter is given by
the time for test bodies with small initial eccentricities to diffuse
to the eccentricity at which they suffer close encounters with the
perturbing body. The theory predicts gaps in the outer asteroid belt
similar to the Kirkwood gaps seen in the inner belt, in agreement
with our recent numerical results. It also predicts that asteroids in
a number of high-order mean motion resonances will possess very short
Lyapunov times (similar to 10,000 years) but removal times comparable
or longer than the life time of the solar system; Helga, Ulla, and
Wingolfia may afford examples of such bodies. Finally, we explore the
relationship between the Lyapunov time and the removal time. We
explain the simple power law relation found in previous numerical
work, and show where it does and does not apply.
 

======================================================================= (3)
M. Lazzarin, M. DiMartino, M. A. Barucci, A. Doressoundiram, M. Florczak:
Compositional properties of near-earth asteroids: spectroscopic comparison
with ordinary chondrite meteorites ASTRONOMY AND ASTROPHYSICS, 1997,
Vol.327, No.1, pp.388-391

DIPARTIMENTO ASTRONOMICO, VIC OSSERVATORIO 5,I-35122 PADUA,ITALY

Some years ago we started a spectroscopic survey, in the visible
region, of Earth-approaching asteroids to investigate their
compositional nature in order to improve the comprehension of their
origin. To date we have obtained low-resolution spectra, in the range
0.5-1.0 mu m, of 1 Aten (3753 1986 TO), 4 Apollo (1864 Daedalus, 5786
Tales, 1989 JA, 2063 Bacchus), and 3 Amor (3352 McAuliffe, 4954 Eric,
5836 1993 MF). Most of them show spectra similar to those of the S
taxonomic class; Bacchus only has a spectrum which resembles those of
more primitive objects (C-type). It has not been possible to
definitively distinguish to which S-subclass the observed objects
belong because the spectra we obtained do not cover the necessary
spectral range to make this investigation as described by Gaffey et
al. (1993). Nevertheless four of the observed objects have visible
spectra similar to those of ordinary chondrites meteorites suggesting
a strong relation between the two classes of objects. Moreover 5836
1993 IMF shows an absorption feature near 6000 Angstrom probably due
to the presence of aqueous altered materials.

======================================================================= (4)
D. K. Yeomans, A.S. Konopliv, J. P. Barriot: The NEAR Radio Science
investigations. JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 1997, Vol.102,
No.E10, pp.23775-23780

CALTECH, JET PROP LAB, 301-150G, PASADENA, CA, 91109

The science objectives for the Near-Earth Asteroid Rendezvous (NEAR)
Radio Science team include determining the masses of asteroids 253
Mathilde (to within 10%) and 433 Eros (<0.1%). While the NEAR
spacecraft is in orbit about Eros, the radiometric spacecraft tracking data,
the optical landmark tracking data, and the lidar altimetry measurements
will be used to determine the gravity field of Eros. Comparisons of this
gravity field with one determined from Eros shape models (assuming constant
density) will provide constraints upon the internal structure of this
asteroid. In addition, the spin state, principal axes, and moments of
inertia will be determined as part of the Radio Science activities. A
campaign to meet the radio science objectives will require the close
cooperation of the NEAR Navigation, Imaging, and Lidar teams.

=====================================================================
(5) AGAINST APOCALYPTIC THINKING

From: "Eugene F. Milone" <milone@acs.ucalgary.ca

Sorry, Benny, I think you are on the wrong side of this issue. Not
every concerned environmentalist is some kind of millenialist. There
are real data showing increases in CO2 and CO2 IS a greenhouse gas.
Next you will be suggesting that the ozone layer is not badly
depleted & getting worse.  Incidentally, the millenialists are not
the environmentalists but the chicken-littles who suddenky discovered
that the Earth has been pelted with rocks!  As I recall, you had
something to do with stirring up that particular frenzy.

Please do not circulate pop news about the latest nutty TV program or
science writer who is trying to make a splash. It is getting a bit
tiring!

The scientific articles are welcome, and I circulate them locally as
serious contributions to the dialogue among scientists.

This last business does no one any good.

Regards,
 - gene

--------------------------------------------------------------------
Dear Gene

Thanks for your message. I'm afraid that I didn't understand your
argument:

There are real data showing increases in CO2 and CO2 IS a greenhouse
gas.

I fully agree, man-made CO2 has dramatically increased in the last 50
years or so. But where is the evidence that this enormous increase
has resulted in any increase of global temperatures? I appreciate
that you disagree with the sceptical position regarding global
warming. But in order to convince me that my scepticism is misplaced,
I would be much obliged if you could tell me where to find data
showing an increase in temperature during the last 50 years. As far
as I am aware, all speculations about a rise of temperature is based
on computer modelling rather than  a c t u a l  meassurments.

Incidentally, the millenialists
are not the environmentalists but the chicken-littles who suddenky
discovered that the Earth has been pelted with rocks!  As I recall,
you had something to do with stirring up that particular frenzy.

The difference between the debate about CO2 triggered global warming on the
one hand and the debate about impact hazards on the other hand is that the
former is not based on any  h a r d  evidence, whereas the latter is. After
all, there have been quite a number of  r e a l natural catastrophes caused
by cosmic impacts during the last 10,000 years. Since we have detected
impact craters,  nobody would doubt these events - although there is no
consensus about the possible effects of such impacts on ecology and culture.
I would also agree with your suggestion that some of the people fascinated
by cosmic catastrophes are millennialists. The problem is, that the impact
hazard is  r e a l - i.e. it is only a question of time when we will be hit
by an extraterrestrial object. So the sceptics and optimists among the
modern catastrophists are working on a technological solution to this
threat. I believe that we humans have both the brains and technological
means to achieving this goal and to protect civilisation from real - rather
than imaginative - disasters.

Best wishes, Benny

================================================================
(6) MAGNETIC ANOMALY IN MANICOUAGAN METEORITE CRATER

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

11/28/1997 2352  Yanks Peak Resources Stakes Claims in Eastern Quebec

VANCOUVER, BRITISH COLUMBIA--(Canadian Corp News, NOVEMBER 25,
1997)--Yanks Peak Resources Ltd. ("YPR") has staked 40 claims located
in the southeast portion of the large  Manicouagan Meteorite Crater
situated 300 km north of Baie-Comeau in Eastern Quebec.

Mineraux Manic Inc. ("MMI") of Montreal, Quebec, which trades on  the
Canadian Dealer Network, is currently drilling several holes in the
middle of the crater and the targeted a large circular magnetic
anomaly that reportedly has a relatively shallow source.

The magnetic anomaly may indicate that the meteorite was a nickel-
iron type, or that its impact caused eruption of deep seated magmas.
The nickel-iron deposits of the world class Sudbury Basin are
believed to have been formed by a similar large meteorite impact
that triggered the intrusion of nickel bearing ultrabasic rocks.
The Manicougan Crater is one of the world's ten largest impact
sites and, with a diameter of about 80 kilometers, is larger than
the present trace of the Sudbury impact site. It is readily
identified in satellite imagery (photographs from orbiting
satellites) of that part of Quebec.

On November 7, 1997 MMI reported that the first drill hole has
proved the presence of a hither to unknown sequence of impact-melt
rocks of a more mafic nature, underneath a "roof" of shock
metamorphosed  unmagnetic grenvillean gneisses, 1500 vertical feet
thick. Dyke-like rocks resembling classic kimberlite
(diamond-bearing breccia pipes) are also present, as well as very
unusual mineral and rock  assemblages, which are now being  analysed.
Once the results are  available, YPR will be determining its own
exploration program.

YPR has completed 5 drill holes for a total of 3000 feet on the  gold
bearing structurally controlled felsic dykes on the Duckworth
property located in the Matawin Gold Belt of Northern Ontario.
Assays from the  drill core are expected within the next 2 weeks.

ON BEHALF OF THE BOARD OF DIRECTORS
Ben Ainsworth, Director

FOR FURTHER INFORMATION PLEASE CONTACT:
Yanks Peak Resources Ltd. Ben Ainsworth Director (604) 681-5939 (604)
683-2308  (FAX) 1-888-888-9122 CDN 1-888-888-9123 USA



CCCMENU CCC for 1997

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