PLEASE NOTE:


*

CCNet 26/2002 - 19 February 2002
-------------------------------


"At the time of the Eltanin impact, Homo erectus was emerging in
Africa, and beginning to spread into cooler Eurasia. It is tempting
to speculate that an impact in the South Pacific could have been a
stimulus for humanity's first great migration out of Africa."
--Henry Gee, Nature 1997


"The phrase mass extinction often calls to mind such potential
culprits as asteroid impacts and volcanism. But new research suggests
that in the case of a die-off of marine creatures that occurred two
million years ago, at the interface of the Pleistocene and Pliocene
epochs, a different phenomenon was to blame. According to a report appearing
in the February 25 issue of the journal Physical Review Letters, cosmic
rays from the explosion of a nearby supernova may have done these
animals in."
--Scientific American, February 2002


"They are the most destructive events in the universe, vast
eruptions that rip apart stars and blast radiation across space. But
supernovae may also play constructive roles in the cosmos - recent
scientific research has revealed that these stellar annihilations had a
crucial impact on human evolution."
--Robin McKie, The Observer, 17 February 2002


(1) STUDY SUGGESTS SUPERNOVA SNUFFED OUT MARINE LIFE TWO MILLION YEARS AGO
    Michael Paine <mpaine@tpgi.com.au>

(2) OCEANIC IMPACTS AND RELATED ENVIRONMENTAL PERTURBATIONS
    A. R. Gersonde

(3) THE ELTANIAN OCEAN IMPACT 2 MILLION YEARS AGO
    NATURE NEWS SERVICE

(4) HOW STAR BLASTS FORGED MANKIND: DID COSMIC DISASTER CHANGE HOMINID
EVOLUTION?
    The Observer, 17 February 2002

(5) COMETARY DUST LOADING DETECTED AROUND THE SUN
    CNN, 18 February 2002

(6) NEWFOUND COMET IS BRIGHTENING
    Astronomy.com, 16 February 2002

(7) WHEN CHIPS FOR BARTERING FALL FROM TEH SKY
    The New York Times, 19 February 2002

(8) SEARCH AND OBSERVATIONS OF SAPCE DEBRIS AND NEAR EARTH OBJECTS AT INASAN
    L.V. Rykhlova et al.

(9) PREDICTION OF THE MOTION OF ASTEROIDS AND COMETS OVER LONG INTERVALS OF
TIME
    I. Wlodarczyk

(10) HYPERVELOCITY IMPACT CRATERING ON ICE
     M.J. Burchell et al.

(11) RADAR CONSTRAINTS ON ASTEROID REGOLITH PROPERTIES
     C. Magri et al.

(12) COLLISION-INDUCED THERMAL EVOLUTION OF A COMET NUCLEUS
     R. Orosei

(13) A RAIN OF ORDINARY CHONDRITIC METEORITES IN THE EARLY ORDOVICIAN
     B. Schmitz et al.

(14) AND FINALLY: CAUGHING A SIGH OF RELIEF AS CAR EXHAUSTS 'MAY SLOW GLOBAL
WARMING'
     Ananova, 19 February 2002


================
(1) STUDY SUGGESTS SUPERNOVA SNUFFED OUT MARINE LIFE TWO MILLION YEARS AGO

>From Michael Paine <mpaine@tpgi.com.au>

Dear Benny
See the Scientific American article below. Note that the Eltanin ocean
impact, possibly by a 4km diameter asteroid, occurred 2.15Ma. Its global
environmental consequences do not appear to have been studied in detail
but simply the ejection of huge quantities of chlorine-laden seawater in
to the atmosphere would have affected (if not wiped out) the ozone
layer.
regards
Michael Paine

Study Suggests Supernova Snuffed out Marine Life Two Million Years Ago
http://www.sciam.com/news/021302/1.html
The phrase mass extinction often calls to mind such potential
culprits as asteroid impacts and volcanism. But new research
suggests that in the case of a die-off of marine creatures that
occurred two million years ago, at the interface of the
Pleistocene and Pliocene epochs, a different phenomenon was
to blame. According to a report appearing in the February 25
issue of the journal Physical Review Letters, cosmic rays from
the explosion of a nearby supernova may have done these
animals in.

Conventional explanations for the extinction, which claimed the
lives of numerous molluscs, look to the emergence of the
Panama isthmus or climate cooling from Northern Hemisphere
glaciations. But analysis of a cluster of stars in our galactic
neighborhood known as the Scorpius-Centaurus association led Narciso
Benítez of Johns Hopkins University and colleagues to conclude otherwise.
They determined that Scorpius-Centaurus has produced 20
supernovae explosions-the swan songs of dying stars-during the last 11
million years. One of these outbursts, the team proposes, occurred around
two million years ago, and took place close enough to Earth
for its cosmic rays to catalyze large-scale destruction of the ozone
layer. The resulting increase in harmful ultraviolet rays from the sun reaching
Earth, they say, could have killed the marine plankton that molluscs
depend on for food.

The supernova explosion hypothesis for mass extinctions has floated
around in academic circles for more than four decades, but the new
study seems to make the strongest case yet. The next step, Benítez and his
co-authors note, will be to determine more precisely the time and
distance at which each supernova explosion took place. "A coincidence in
time between the [supernova] expected to have the strongest effects on the
biosphere and the Pleistocene-Pliocene extinction," they write, "would
strongly support the existence of a link between both events."

-Kate Wong
c2001 Scientific American

===============
(2) OCEANIC IMPACTS AND RELATED ENVIRONMENTAL PERTURBATIONS

R. Gersonde, Alfred
Wegener Institute, P.O. Box 120161, Bremerhaven 27515, Germany.
Catastrophic Events Conference, Vienna, 2000 3049.pdf

Only ca.13% of the ca.165 known terrestrial impact structures have been
identified to originate in marine environments. The marine impacts have been
reported from shallow water marginal or epicontinental seas, except one, the
Eltanin impact, that was discovered in the deep-sea basin of
the southeast Pacific. Reasons for the mismatch between the numbers of
continental and deep-sea impacts include (i) the relatively young age of
oceanic basins, (ii) the post-impact burial of marine impact structures,
(iii) the deceleration and disintegration of small projectiles in the
water column preventing the formation of impact traces at the deep-sea
floor, (iv) the inaccessibilty of the deep-sea floor, and (v) the lack of
programs for the detection of oceanic impacts. In contrast to continental
impacts, oceanic impacts will generate megatsunamis that could potentially
devastate coastlines. This includes destruction of coral reefs,
destabilisation of shelf ice and shelf deposits and the backwash of
terrestrial material. Future oceanic
impacts represent a potential hazard because impact-generated large-scale
tsunamis can cause enormous loss in populated coastal areas, including areas
located at great distances of the impact ground-zero. Another specific
threat related to oceanic impacts is the ejection of large
quantities of water and salt into the atmosphere. Such deposition might lead
to depletion of the ozone shield, to acidification of surface regions and
could affect the Earth´s albedo and the power of greenhouse forcing. Despite
the great potential of oceanic impacts for causing sudden
disturbance of past and future Earth´s climate, environment and life, our
knowledge on these processes is still quite limited. To date, the only
example for a deep-ocean impact is the late Pliocene (2.15 Ma) Eltanin
impact in the 5000 m deep Bellingshausen Sea. Originally discovered in 1981,
based on an Ir-anomaly[1], and documented in more detail in 1997 [2], the
Eltanin impact represents a baseline for further impact-related studies and
modeling, and the identification of other deep-sea impacts. Combined with
seismic and sediment core data, numeric modeling
represents the most important tool to understand the complex impact-related
processes such as short-term effects (pressure, velocities, shock waves) in
the water column, large scale oceanic phenomena (e.g. tsunami generation and
propagation), the effects of shock waves and oceanic processes on the
sediment cover and basement, as well as perturbations in atmospheric and
environment.

References: [1] Kyte, F.T. et al. (1981) Nature, 292, 417-420. [2]
Gersonde, R. et al. (1997) Nature, 390, 357-363.
Catastrophic Events Conference 3049.pdf

=============
(3) THE ELTANIAN OCEAN IMPACT 2 MILLION YEARS AGO

>From NATURE NEWS SERVICE
http://www-geology.ucdavis.edu/~GEL3/Plioceneimpact.html

Ocean splashdown
by Henry Gee

An asteroid between one and four km in diameter that splashed into the
Southern Ocean, 1500 km SW of Chile, just over two million years ago, may
have worsened a period of global cooling that saw the emergence of modern
humans. The asteroid impact explains several other puzzles, too, as Rainer
Gersonde of the Alfred Wegener Institute for Polar and Marine Research in
Bremerhaven and colleagues discuss in the 27 November 1997 Nature.

The impact in question was first discovered during a cruise of the Eltanin
in the 1960s: betrayed by anomalously high amounts of iridium in ocean-bed
cores. The Eltanin impact is the only example of the 140 known on Earth to
have occurred in the deep ocean. Given that 70% of the Earth's surface is
underwater, and most of that is ocean, we would expect most incoming
asteroids and comets to meet watery graves. Statistics suggests that around
500 bodies the size of the Eltanin asteroid hit the oceans in the past 540
m.y.: almost one every million years, on average. This is why the Eltanin
impact site is so valuable, and why Gersonde and his colleagues have taken
another look, their results coming from a cruise in 1995 by the research
ship Polarstern.

The impact left a distinctive 'signature' of geological layers, very like
that of the Chicxulub impact. Lowest in the 'impact' sequence is a thick
layer of disordered rubble, full of chunks of rock up to 50 cm across: this
layer represents the large-scale disturbance immediately after the impact as
the ten-megaton blast ripped up the ocean floor. This layer took around four
hours to settle after the blast. Smaller particles, such as grains of sand,
took longer to settle, explaining why this layer was found immediately above
the rubble layer.

Capping the whole sequence is a thin layer of very fine sediment, dispersed
over a wide area. This would have contained fine-grained material (including
vaporized asteroid) flung high into the air and which took days or months to
settle out. This layer contained the iridium.

The Eltanin asteroid was much smaller, less than half the diameter of the
asteroid of the Chicxulub impact. There is no trace of a submarine Eltanin
crater; indeed, most of the asteroid probably vaporized before it could
leave much of a scar on the ocean floor. Nevertheless, Eltanin was still an
impact to be reckoned with, being just large enough to disturb the global
ecosystem. The impact would have blasted sediment high into the atmosphere,
explaining why fossils of microscopic deep-sea diatoms made their way to the
mountainous interior of Antarctica. It would also have sent terrifyingly
high tsunamis to broach on coasts all over the South Pacific and Southern
Oceans. These would have washed hundreds of metres inland, explaining the
strange jumble of terrestrial and marine animals from contemporary deposits
in Peru.

The impact would also have sent enormous quantities of water and dust into
the atmosphere, which would have influenced the climate. Although polar
ice-sheets had become well-established by that time, the Earth was yet to
settle into the pronounced cycle of continental glaciation that has
characterized the past 1-2 million years.

At the time of the Eltanin impact, Homo erectus was emerging in Africa, and
beginning to spread into cooler Eurasia. It is tempting to speculate that an
impact in the South Pacific could have been a stimulus for humanity's first
great migration out of Africa.

©Macmillan Magazines Ltd 1997 - NATURE NEWS SERVICE

=============
(4) HOW STAR BLASTS FORGED MANKIND: DID COSMIC DISASTER CHANGE HOMINID
EVOLUTION?

>From The Observer, 17 February 2002
http://www.observer.co.uk/uk_news/story/0,6903,651829,00.html

Cosmic radiation two million years ago had a crucial impact on our evolution


Robin McKie

They are the most destructive events in the universe, vast eruptions that
rip apart stars and blast radiation across space.

But supernovae may also play constructive roles in the cosmos - recent
scientific research has revealed that these stellar annihilations had a
crucial impact on human evolution.

Two million years ago, just as the Earth's primitive apemen were evolving
into big-brained humans, a pair of supernovae explosions occurred near
Earth.

Our planet was buffeted with blasts of radiation - with devastating effects.
'These supernovae would have blown away our protective ozone layer,' said Dr
Narciso Benítez, of Johns Hopkins University, Baltimore.

'Earth lost its protection against ultraviolet solar rays and for several
hundred years the planet would have been battered by intense radiation. All
sorts of mutational damage to animals' DNA would have occurred. New species
could have emerged as a result. It is possible Homo sapiens may have been
one of these.'

A supernova occurs when a hot, dense star burns up its fuel too quickly and
suddenly implodes, generating shock waves and intense blasts of radiation
across space. When a supernova explodes, it outshines all the other 200
billion stars that make up our galaxy, the Milky Way.

The likely impact of a supernova's radiation led scientists in the past to
speculate that one may have affected evolution on Earth. But calculations
indicated that fields of interstellar gas would have dissipated a
supernova's radiation and blunted its impact.

However, Benítez and his colleague, Dr Jesús Maíz-Apellániz, of the Space
Telescope Science Institute in Baltimore, now believe that at least two
supernovae occurred near Earth two million years ago. The first would have
blasted space free of interstellar particles; the second would have struck
Earth at full force, destroying its ozone layer.

'Supernovae are very rare. So two such explosions occurring relatively close
together might seem unlikely. However, we have discovered that around this
time a group of hot, dense young stars - just the type that turn supernova -
passed relatively close to Earth,' said Maíz-Apellániz.

'Some of this group - known as the Sco-Cen group - would have got within 100
light years of us, which, astronomically, is not a great distance. Our
calculations suggest that two or three of these exploded as supernovae.'

In short, Earth was hit by an astronomical double whammy - though the
discovery that supernova-prone stars passed near Earth two million years ago
does not, on its own, provide complete proof, as the two scientists admit.

However, further support for the theory, to be published in Physical Review
Letters next week, has been found by scientists studying samples of
sediments from the Pacific ocean floor. German researchers recently
uncovered an isotope of iron known as iron-60 in ocean bed samples laid down
about two million years ago. 'Iron-60 is made by only one thing in nature -
a supernova,' said Benitez. 'A supernova sprays space with many different
elements. Many are rare - like iron-60. These particles hit our atmosphere
and settle like a thin layer of dust over the planet.'

Intriguingly, the iron-60 layer found by the German group did not come from
a single supernova but appeared to come from a number of them. 'Different
layers seem to have fallen at different times, but all around two million
years ago,' said Benítez.

In addition, observations of space around our Sun have revealed that unlike
the rest of the galaxy, space near us has little interstellar gas in it.
'Essentially it is missing much of its dust and gas - just as if a supernova
had cleaned it out,' added Maíz-Apellániz.

In other words, our tiny corner of the galaxy appears to have been swept
clean by a supernova brush about two million years ago. Intriguingly, at
just this time, a set of extinctions - known as the Pliocene/Pleistocene
extinctions - is also known to have occurred.

Geologists have found that plankton and molluscs were wiped out in vast
numbers and that land animals and plants were also affected. 'We now think
these creatures were killed off because Earth's ozone was blasted away by
two or more supernovae,' said Benítez.

'There would have been no protection against the Sun's intense ultraviolet
radiation. All sorts of changes could have resulted.'

It was also around this time that mankind's direct ancestor, Homo erectus,
the species considered to be the first true human being, appeared in Africa
and Asia after replacing more primitive ape-like creatures such as
Australopithecus africanus. These beings may have been some of the lucky few
who were able to advantage of conditions in these hazardous, radioactive
times. This triumph only occurred thanks to this celestial intervention,
however.

'It is a very interesting idea,' said Professor Chris Stringer, of the
Natural History Museum in London. 'Certainly, quite a number of extinctions
around this period. At the same time, Homo erectus was beginning to make its
way in the world.

'However, we would have to tie down the datings of the supernovae eruptions
and also the dates that the layers of the iron-60 were deposited before we
could start to take such an idea seriously as a cause of the changes we see
in the fossil records'.

Copyright 2002, The Observer

MODEARTOR'S NOTE: On cosmic impacts as agents of punctuated human evolution,
see: Reinventing Darwin Again: How Asteroids Impacted Human Evolution
http://www.space.com/searchforlife/human_evolution_010424-1.html

=======
(5) COMETARY DUST LOADING DETECTED AROUND THE SUN

>From CNN, 18 February 2002
http://www.cnn.com/2002/TECH/space/02/18/sun.ring/index.html

Sun ring could point the way to distant planet systems

By Richard Stenger

(CNN) -- A newly detected disk around the sun could narrow down the search
of other star systems that might harbor planets, according to scientists.

Astronomers with the European Space Agency said this month that they had
found the first direct evidence of the bright dust ring, located beyond the
orbit of Saturn.

Young stars are known to posses thick bands of dust, gas and debris. In the
inner regions, planets can coalesce. Farther out, the more thinly
distributed material can clump into sparse bands of miniature ice objects.

Any dusty leftovers disappear into deep space. But if an older star such as
the sun possesses a dusty ring, some hidden source of material must be
sustaining it, the agency's researchers say.

Replenishing the one around the sun requires 50 tons of dust each second,
estimated agency scientist Markus Landgraf.

His colleague Malcolm Fridlund elaborated.

"The dust has to come from somewhere," Fridlund said. "The only explanation
is that the star has planets, comets, asteroids or other bodies that collide
and generate the dust."

The dust ring is fed by the constant collisions of primordial comets in the
outer reaches of the solar system, the so-called Kuiper Belt Objects,
according to the researchers.

Viewed from afar, the sun's ring likely would resemble a disk such as this
one around a star called HR 4796A.   

The finding could give a major boost to the search for planets around other
stars in the galaxy.

"If we see a similar dust ring around a mature star like the sun, we'll know
it must have asteroids or comets," Landgraf said. "If we see gaps in the
dust ring, it will probably have planets that are sweeping away the dust as
they orbit."

Satellites such as the Cosmic Background Explorer and Ulysses helped
astronomers find the disk around the sun. Future planet-seeking missions
such as the space agency's Eddington and Darwin may help refine the search
around other stars in the coming decades.

Based on data from satellites and observatories, promising places to
investigate include the Vega and Epsilon Eridani star systems, researchers
say.

Copyright 2002, CNN

==========
(6) NEWFOUND COMET IS BRIGHTENING

>From Astronomy.com, 16 February 2002
http://www.astronomy.com/Content/Dynamic/Articles/000/000/000/763khkce.asp

A newly discovered comet could become naked-eye this spring.
by Vanessa Thomas

While Southern Hemisphere observers have been treated to a dazzling Comet
LINEAR lately, a new comet has shown up in Northern Hemisphere skies and may
put on nearly as nice of a show this spring.

During the last few days of January, comet watchers north of the equator
wished they could transport themselves southward as Comet 2000 WM1 (LINEAR),
at the time only visible from the Southern Hemisphere, flared to better than
3rd magnitude. Just a couple days later, though, two comet hunters found a
new fuzzy object in the western sky that soon eased the pain of northern
observers unable to see Comet LINEAR's grand display.

On February 1 two comet hunters, Kaoru Ikeya of Japan and Daqing Zhang of
China, independently reported spotting an unidentified comet in their
evening skies. Using a 25-centimeter (10-inch)  telescope, Ikeya (who has
discovered or co-discovered several comets before), estimated that this new
visitor was about 9th magnitude. Zhang, who used a 20-centimeter (8-inch)
reflector, estimated that it was slightly better at magnitude 8.5.
 
Soon, other amateur astronomers, from both hemispheres, reported seeing the
comet as well. Over the past two weeks, they've watched as Comet 2002 C1
(Ikeya-Zhang) has brightened to better than magnitude 7.5. Additionally,
some observers report that a thin tail has already begun to develop.
 
Early estimates of the comet's orbit has it reaching perihelion on March 8.
Astronomers currently predict that its peak brightness could hit magnitude 4
several days later. Unfortunately, Comet Ikeya-Zhang will still be quite
close to the sun at that time. But it has the potential to remain a
naked-eye object through April. Comet watchers know their favorite targets
can be unpredictable and will keep a close watch on Comet Ikeya-Zhang in
case it has some surprises in store.

Currently in Cetus and moving northward, Comet Ikeya-Zhang will make its
closest approach to the sun while in Pisces before moving into Pegasus in
late March. To view star charts showing the comet's position over the next
two weeks, click on the "related stories" below.

Copyright © 1996-2002 Kalmbach Publishing Co. 

============
(7) WHEN CHIPS FOR BARTERING FALL FROM TEH SKY

>From The New York Times, 19 February 2002
http://www.nytimes.com/2002/02/19/science/space/19METE.html

By KENNETH CHANG
 
Want a piece of a historic meteorite from the Smithsonian collection or
maybe the Natural History Museum in London?

Offer a blank check and the answer will be, sorry, it is not for sale.

But there is a good chance that the curators at those and other natural
history museums will give it to you - if you can trade another
extraterrestrial rock they want.

Rare meteorites act as their own currency, giving private collectors access
to collections at the most prestigious museums.

That is how two pieces of the Willamette Meteorite - the prized, 15 1/2-ton
centerpiece of American Museum of Natural History's planetarium - wound up
at auction this month, to the dismay of Oregon Indians who regard it as
sacred and to the concern of some museum association officials.

In recent years, an avid collector's market has pushed prices for precious
meteorites to thousands of dollars an ounce, often too expensive for
universities and museums. What academic institutions do have are historic
meteorites that collectors want a piece of. Hence, they trade.

"We're forced into doing that kind of thing," said Dr. Rhian H. Jones,
curator at the University of New Mexico's Institute of Meteoritics. "The
private dealers, they're not donating the material to research. If we want
to do the research, we have to get the material into the collection. It
doesn't harm our collection significantly to trade a small piece of
meteorite that we have a large amount of it for something that has
scientific value."

Once in private hands, a museum meteorite is typically cut into smaller and
smaller pieces and sold and resold at sometimes considerable profit. Or the
collector makes more trades to gain yet more rocks.

Collectors say the high values have spurred more people to hunt for
meteorites, and that aids the scientists.

"If it were not for the new meteorite bonanza of the 90's, the research
community would never have had so many new rare and exciting specimens made
available to them," said Michael I. Casper, a meteorite dealer and collector
in Ithaca, N.Y.

But for museum visitors, sometimes there is slightly less to see. At the top
of the Willamette Meteorite - the largest ever found in the United States -
is a smooth, polished surface about a foot wide where the museum cut off a
28-pound chunk about four years ago. Small fragments from that chunk are now
for sale at mhmeteorites.com. The Web site informs the viewer: "Available
exclusively at Mile High Meteorites."

The museum had traded the 28- pound chunk to a private collector, Darryl
Pitt of New York City, for a small piece of a meteorite from Mars, and Mr.
Pitt, in turn, cut a 3.4- ounce slice off his chunk, which he auctioned off
on Feb. 10 for $11,000.

The buyer, Matt Morgan, owner of Mile High Meteorites, will cut it into six
or seven pieces, keeping some, selling others. A second, smaller piece of
the meteorite, which Mr. Pitt had obtained in a trade with the Natural
History Museum in London, sold for $3,300.

The auctions have upset descendants of the Clackamas Indians in Oregon,
where the meteorite was found. They regard it as a spiritual union of earth,
sky and water. The trade between Mr. Pitt and the museum occurred a couple
of years before the claim; the museum says it will not cut any more pieces.

The buyer of the smaller piece, Dr. David Wheeler, a chiropractor in West
Linn, Ore., has said he may donate it to the Confederated Tribes of Grande
Ronde, which includes the Clackamas. Mr. Morgan said Friday that he and his
two fellow investors would also give a small piece to the tribes.

But even had there been no cultural considerations, some find it troubling
that a piece of a meteorite was cut off not to be studied, but to fill the
desire of a collector.

"It's almost defacing," Nancy Heller of New York City, a visitor to the
planetarium last week, said of the Willamette Meteorite. "I can't imagine
anyone deliberately wanting to damage a work of art. This is not exactly a
work of art, but it is a museum."

Dr. Geoffrey Lewis, chairman of the ethics committee of the International
Council of Museums, said that he was troubled by some of what he had heard
about the meteorite trades and that his committee would review the practice
when it met this summer in Paris. "Clearly, there are many issues there,
which should be examined," he said.

He said he could not comment on the Willamette Meteorite trades because he
did not know the details. But he cited several sections in the council's
Code of Professional Ethics, which state that there should be a "strong
presumption" against getting rid of specimens, that museum professionals
should not participate in the buying or selling of objects for profit, even
indirectly, and that collections should not be treated as "realizable
assets."

Dr. Michael J. Novacek, the provost of science at the American Museum of
Natural History, said tmuseumis not a member of the international council
and that the museum's practices were entirely in line with the code of
ethics established by the American Association of Museums, which states that
sales or trades should occur "solely for the advancement of the museum's
mission."

The trade with Mr. Pitt brought the museum a sample of a very rare Martian
meteorite, more important scientifically than the fairly common iron of the
Willamette Meteorite.

"Our motive is to raise the scientific value of the collection," Dr. Novacek
said. "We don't view ourselves as out of compliance with any ethics."

Still, when meteorite collectors view museum collections, they sometimes
seem more like shoppers than visitors.

Mr. Morgan of Mile High Meteorites said he regularly traded with museums at
a couple of universities. When he gets something new, he sends e-mail
messages to the curators: "I say, are you guys interested in any of this?"

He keeps catalogs of the museums' collections, so if they're interested, he
can suggest what he would like in return.

Copyright 2002 The New York Times Company

============
(8) SEARCH AND OBSERVATIONS OF SAPCE DEBRIS AND NEAR EARTH OBJECTS AT INASAN

Rykhlova LV, Bagrov AV, Barabanov SI, Kasimenko TV, Mikisha AM, Smirnov MA:
Search and observations of Space Debris and near Earth objects at INASAN
SPACE DEBRIS. ADVANCES IN SPACE RESEARCH  28 (9): 1301-1307 2001

The concept of Space Debris is tightly connected with the rapidly developing
activity of men in space, and accompanied by a contamination of the
surrounding space by artificial debris. Besides artificial debris, in the
vicinity of the Earth is moving a large number of natural celestial bodies:
comets, mini-comets, asteroids, meteor streams with fragments of various
sizes and chemical composition. Our activity in the observations
concentrates in three directions: position observations of artificial
objects on the geostationary orbit (GEO); photometric observations on GEO
and LEO (low orbits); observations of natural near-Earth objects (NEO).
Scientific investigations are carried out in the following directions:
explosions of upper stages of rockets in LEO and GEO; solar radiation
pressure and its influence on the evolution of orbits; space debris on GEO;
natural objects' population in near-Earth space. (C) 2001 COSPAR. Published
by Elsevier Science Ltd. All rights reserved.

Addresses:
Rykhlova LV, Russian Acad Sci, Inst Astron, Pyatnitskaya St 48, Moscow
109017, Russia
Russian Acad Sci, Inst Astron, Moscow 109017, Russia

Copyright © 2002 Institute for Scientific Information

============
(9) PREDICTION OF THE MOTION OF ASTEROIDS AND COMETS OVER LONG INTERVALS OF
TIME

Wlodarczyk I: Prediction of the motion of asteroids and comets over long
intervals of time
ACTA ASTRONOMICA 51 (4): 357-376 2001

Difference of the mean anomalies of two starting orbits of a minor planet or
a comet which only differ by an error of calculating of one of the orbital
elements grows rapidly with time. This means that it is almost impossible to
predict behavior of minor planets or comets on the orbit outside the period
of time called the time of stability in our work. The time of stability for
some selected minor planets and comets are given. For some minor planets and
comets the time of stability is surprisingly short, about several hundreds
years only.

Addresses:
Wlodarczyk I, WPKIW, Astronom Observ Chorzow Planetarium, PL-41501 Chorzow,
Poland
WPKIW, Astronom Observ Chorzow Planetarium, PL-41501 Chorzow, Poland

Copyright © 2002 Institute for Scientific Information

=========
(10) HYPERVELOCITY IMPACT CRATERING ON ICE

Burchell MJ, Grey IDS, Shrine NRG: Laboratory investigations of
hypervelocity impact cratering in ice ADVANCES IN SPACE RESEARCH 28 (10):
1521-1526 2001

Hypervelocity impact experiments on water ice targets have been performed
using a two stage light gas gun. The resulting craters were measured to
obtain the crater depth and diameter. From the data set for 23 impact
craters, damage equations have been obtained which give the crater depth
(diameter) in terms of the dependence on impact velocity, projectile
diameter and projectile density. The resulting damage equations are compared
to those for another brittle material, glass. Scaling of the excavated
crater volume with energy is shown to obey a simple power law over 10 orders
of magnitude in energy (10(-7) to 10(3) J). (C) 2001 COSPAR. Published by
Elsevier Science Ltd. All rights reserved.

Addresses:
Burchell MJ, Univ Kent, Unit Space Sci & Astrophys, Canterbury CT2 7NR,
Kent, England
Univ Kent, Unit Space Sci & Astrophys, Canterbury CT2 7NR, Kent, England

Copyright © 2002 Institute for Scientific Information

===========
(11) RADAR CONSTRAINTS ON ASTEROID REGOLITH PROPERTIES

Magri C, Consolmagno GJ, Ostro SJ, Benner LAM, Beeney BR: Radar constraints
on asteroid regolith properties using 433 Eros as ground truth
METEORITICS & PLANETARY SCIENCE 36 (12): 1697-1709 DEC 2001

Radar data enable us to estimate an asteroid's near-surface bulk density,
thus providing a joint constraint on near-surface porosity and solid
density. We investigate two different approaches to simplifying this joint
constraint: estimating solid densities by assuming uniform porosities for
all asteroids; and estimating porosities by assuming uniform mineralogy
within each taxonomic class. Methods used to estimate asteroids'
near-surface solid densities from radar data have not previously been
calibrated via independent estimates. Recent spacecraft results on the
chondritic nature of 433 Eros now permit such a check, and also support
porosity estimation for S-class objects. We use radar albedos and
polarization ratios estimated for 36 main-belt asteroids and nine near-Earth
asteroids to estimate near-surface solid densities using two methods, one of
which is similar to the uncalibrated algorithms used in previous studies,
the other of which treats Eros as a calibrator. We also derive porosities
for the same sample by assigning solid densities for each taxonomic class in
advance. Density-estimation results obtained for Eros itself are consistent
with the uncalibrated method being valid in the mean; those derived for the
full sample imply that uncalibrated solid densities are, at most, a few tens
of percent too large on average. However, some derived densities are
extremely low, whereas most porosity estimates are physically plausible. We
discuss the relative merits of these two approaches.

Addresses:
Magri C, Univ Maine, 173 High St,Preble Hall, Farmington, ME 04938 USA
Univ Maine, Farmington, ME 04938 USA
Univ Arizona, Steward Observ, Vatican Observ Res Grp, Tucson, AZ 85721 USA
CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA

Copyright © 2002 Institute for Scientific Information

==========
(12) COLLISION-INDUCED THERMAL EVOLUTION OF A COMET NUCLEUS

Orosei R, Coradini A, De Sanctis MC, Federico C: Collision-induced thermal
evolution of a comet nucleus in the Edgeworth-Kuiper Belt
ADVANCES IN SPACE RESEARCH 28 (10): 1563-1569 2001

In this work, we attempt an order-of-magnitude estimate of the effects of
heating caused by low-velocity collisions on the structure and composition
of an Edgeworth-Kuiper Belt object. This was done by using a numerical code
developed for the study of comet nuclei. This code solves the heat
conduction and gas diffusion equations in one dimension, within a
spherically simmetric porous body made of a mixture of ices and dust. Ices
can sublimate, gas can flow within the porous matrix, and dust can be
ejected by the gas flow escaping from the object. The code was adapted to
the EKO case by adding the heat released by an impact in the interior of the
body. Within the uncertainties in the values of parameters describing the
EKO structure and the heat release due to impacts, it was found that the
outcome of even a large collision cannot be taken for granted: in some
cases, the impacted body is altered to depths of more than 1 km, while in
some other cases very small effects are produced. The results also point to
the interesting possibility of heat buildup within an EKO due to multiple
impacts. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights
reserved.

Addresses:
Orosei R, CNR, Ist Astrofis Spaziale, Via Fosso Cavaliere 100, I-00133 Rome,
Italy
CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy
Univ Perugia, Dipartimento Sci Terra, I-06100 Perugia, Italy

Copyright © 2002 Institute for Scientific Information

===========
(13) A RAIN OF ORDINARY CHONDRITIC METEORITES IN THE EARLY ORDOVICIAN

Schmitz B, Tassinari M, Peucker-Ehrenbrink B: A rain of ordinary chondritic
meteorites in the early Ordovician
EARTH AND PLANETARY SCIENCE LETTERS 194 (1-2): 1-15 DEC 30 2001

Forty fossil meteorites with a total original mass of similar to7.7 kg have
been recovered in the first systematic search for fossil meteorites, pursued
in an active quarry in Lower Ordovician (480 Ma) marine limestone in
southern Sweden. The meteorites represent at least 12 different falls over a
seafloor area of similar to6000 m(2) during less than or equal to1.75 Myr,
making the quarry one of the most meteorite dense areas known in the world.
Geochemical analyses of relict chromite grains indicate that all or most of
the meteorites are ordinary chondrites and probably L chondrites. Mechanisms
for meteorite delivery from the asteroid belt to Earth were the same 480 Ma
as today, however, the flux was one to two orders of magnitude higher, most
likely reflecting the disruption of the L chondrite parent body at about
that time. This is a major event in late solar-system history, which may
also have led to an enhanced flux of asteroids to Earth during similar to 30
Myr. (C) 2001 Elsevier Science B.V. All rights reserved.

Addresses:
Schmitz B, Ctr Earth Sci, POB 460, SE-40530 Gothenburg, Sweden
Ctr Earth Sci, SE-40530 Gothenburg, Sweden
Vaner Museum, SE-53117 Linkoping, Sweden
Woods Hole Oceanog Inst, Dept Marine Chem & Geochem, Woods Hole, MA 02543
USA

Copyright © 2002 Institute for Scientific Information

===========
(14) AND FINALLY: CAUGHING A SIGH OF RELIEF AS CAR EXHAUSTS 'MAY SLOW GLOBAL
WARMING'

>From Ananova, 19 February 2002
http://www.ananova.com/news/story/sm_524431.html?menu=news.scienceanddiscovery

A climate expert says global warming could be balanced out by the cooling
effect of car exhausts.

He says aerosols pumped out by vehicles can lead to the formation of rain
droplets in clouds which, in turn, has a cooling effect.

Computer climate models which predict global warming may not have taken this
effect into account.

Ran Ramanathan, of the Scripps Institution of Oceanography in California,
says aerosol output has increased by about a third since 1980.

The Times reports he has calculated that the cloud-seeding effect of
aerosols could lower temperatures locally by up to 2.5C.

Aerosols are also produced by industrial processes and naturally by
volcanoes but do have some negative health and environmental effects.

Ramanathan said: "There is a possibility that it might add more impact or
virtually balance all the impact of greenhouse warming."

Copyright 2002, Ananova

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