PLEASE NOTE:


*

CCNet 66/2002 - 7 June 2002
-----------------------------------

    "Military strategists and space scientists that wonder and worry about a
run-in between Earth and a comet or asteroid have additional worries in
these trying times. With world tensions being the way they are, even a small
incoming space rock, detonating over any number of political hot-spots,
could trigger a country's nuclear response convinced it was attacked by an
enemy. Being struck by a giant asteroid or comet isn't the main concern for
Air Force Brigadier General Simon Worden, deputy director of operations for
the United States Space Command at Peterson Air Force Base, Colorado. "We
now have 8 or 10 countries around the world with nuclear weapons...and not
all of them have very good early warning systems. If one of these things
hits, say anywhere in India or Pakistan today, we would   have a very bad
situation. It would be awfully hard to explain to them that it wasn't the
other guy," Worden pointed out."
              --Leonard David, Space.com, 6 June 2002


    "I think Mother Nature has given us yet another wake-up call. Objects
the size of 2002 EM7 pass as close as this one did every two weeks or so. We
just haven't found them all yet."
               --Don Yeomans, JPL, 3 June 2002



(1) FIRST STRIKE OR ASTEROID IMPACT?
    Space.com, 6 June 2002

(2) SCIENTISTS STUDY DEFENDING EARTH AGAINST ASTEROIDS
    Scripps Howard News Service, 3 June 2002

(3) STUDY: "PERMIAN-TRIASSIC MASS EXTINCTION NOT CAUSED BY COSMIC IMPACT"
    CNN, 6 June 2002

(4) FORGET NEO IMPACTS: "VOLCANOES KILLED OFF PERMIAN SPECIES"
    Nature, 7 June 2002

(5) FLOOD BASALT: BIGGER AND BADDER
    Science, 7 June 2002

(6) FORGET NEO IMPACTS: "COSMIC STORM KILLED OFF DINOSAURS"
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(7) PERMIAN IMPACT CAUSED LARGEST MASS EXTINCTION ON EARTH
    Space Daily, 31 August 2001

(8) AN EXTRATERRESTRIAL IMPACT AT THE PERMIAN-TRIASSIC BOUNDARY?
    Science, Volume 293, Number 5539, Issue of 28 Sep 2001, p. 2343.

(9) ASTEROID TSUNAMI SIMULATION: NEW WAVE SUPERCOMPUTERS CATCH BIG WAVES
    Space Daily, 5 June 2002

(10) THE INSPIRATION OF ASTRONOMICAL PHENOMENA -- FOURTH CONFERENCE
     Rolf Sinclair <rolf@SANTAFE.EDU>

(11) CRATERS?
     Giesinger Norbert <norbert.giesinger@siemens.com>

(12) WHY IS MARS SO HARD?
     James Oberg <joberg@houston.rr.com>


================
(1) FIRST STRIKE OR ASTEROID IMPACT?

>From Space.com, 6 June 2002
http://space.com/scienceastronomy/astronomy/nss_asteroid_020606.html

First Strike or Asteroid Impact? The Urgent Need to Know the Difference

By Leonard David
Senior Space Writer

DENVER, COLORADO -- Military strategists and space scientists that wonder
and worry about a run-in between Earth and a comet or asteroid have
additional worries in these trying times. With world tensions being the way
they are, even a small incoming space rock, detonating over any number of
political hot-spots, could trigger a country's nuclear response convinced it
was attacked by an enemy.

Getting to know better the celestial neighborhood, chock full of passer-by
asteroids and comets is more than a good idea. Not only can these objects
become troublesome visitors, they are also resource-rich and scientifically
bountiful worlds.

Slowly, an action plan is taking shape.

Noted asteroid and comet experts met here May 23-27, taking part in the
National Space Society's International Space Development Conference 2002.

Sweat the small stuff

Being struck by a giant asteroid or comet isn't the main concern for Air
Force Brigadier General Simon Worden, deputy director of operations for the
United States Space Command at Peterson Air Force Base, Colorado. He sweats
the small stuff.

Worden painted a picture of the next steps needed in planetary defense. His
views are not from U.S. Department of Defense policy but are his own
personal perspectives, drawing upon a professional background of astronomy.

For example, Worden said, several tens of thousands of years ago an asteroid
just 165-feet (50 meters) in diameter punched a giant hole in the ground
near Winslow, Arizona. Then there was the Tunguska event. In June 1908, a
massive fireball breached the sky, then exploded high above the Tunguska
River valley in Siberia. Thought to be in the range of 165-feet (50 meters)
to 330 feet (100 meters) in size, that object created a devastating blast
equal to a 5 to 10 megaton nuclear explosion. A similar event is thought to
have taken place in the late 1940s in Kazakhstan.

"There's probably several hundred thousand of these 100-meter or so
objects...the kind of ones that we worry about," Worden said. However, these
are not the big cosmic bruisers linked with killing off dinosaurs or
creating global catastrophes.

On the other hand, if you happen to be within a few tens of miles from the
explosion produced by one of these smaller near-Earth objects, "you might
think it's a pretty serious catastrophe," Worden said.

"The serious planetary defense efforts that we might mount in the next few
decades will be directed at much smaller things," Worden said. Some 80
percent of the smaller objects cross the Earth's orbit, "some of which are
potentially threatening, or could be in the centuries ahead," he said.

Nuclear trigger

One set of high-tech military satellites is on special round-the-clock
vigil. They perform global lookout duty for missile launches. However, they
also spot meteor fireballs blazing through Earth's atmosphere. Roughly 30
fireballs detonate each year in the upper atmosphere, creating equivalent to
a one-kiloton bomb burst, or larger, Worden said.

"These things hit every year and look like nuclear weapons. And a couple
times a century they actually hit and cause a lot of damage," Worden said.

"We now have 8 or 10 countries around the world with nuclear weapons...and
not all of them have very good early warning systems. If one of these things
hits, say anywhere in India or Pakistan today, we would have a very bad
situation. It would be awfully hard to explain to them that it wasn't the
other guy," Worden pointed out.

Similarly, a fireball-caused blast over Tel Aviv or Islamabad "could be
easily confused as a nuclear detonation and it may trigger a war," Worden
said.

Meanwhile, now moving through the U.S. Defense Department circles, Worden
added, is a study delving into issues of possibly setting up an asteroid
warning system. That system could find a home within the Cheyenne Mountain
Complex outside Colorado Springs, Colorado. The complex is the nerve center
for the North American Aerospace Defense Command (NORAD) and United States
Space Command missions.

Next steps

Where do we go from here?

An important step, Worden said, is cataloging all of the objects that are
potentially threatening, down to those small objects that could hit and
destroy a city. To do this type of charting, military strategists now
champion a space-based network of sensors that keep an eye on Earth-circling
satellites. These same space sentinels could serve double-time and detect
small asteroids, he said.

Secondly, more money should be applied to building microsatellites. Some of
these tiny craft might be placed in a kind of sleep mode - put in parking
orbits and ready to spring into action in the event of a intimidating
intruder of the asteroid kind.

For one, these microsatellites can offer "up-close and personal" looks at
menacing objects. Is an asteroid, for example, solid rock or rubble pile?
The answer would make a big difference in dealing with an object having
Earth's name on it. These microsatellites could ram an object too, adding
extra energy to the body and putting it on an out-of-harms-way trajectory.

"Before we start detonating nuclear weapons in space to move something, we
ought to think long and hard how we really want to do this," Worden said. "A
lot of folks believe the next step for NASA is not go back to the Moon or on
to Mars, but go to the asteroids. That's something we ought to be thinking
about," he added.

Asteroids are interesting from a scientific and space industrialization
basis, as well as being a threat, Worden said.

"For fear...for greed...for curiosity. Asteroids are about the only thing in
space that combine all three of those," Worden concluded.

Unlike the dinosaurs

Advancements are being made to take the edge off impact hazard worry, said
Clark Chapman, planetary scientist at the Southwest Research Institute in
Boulder, Colorado.

"For one, to mitigate impact hazard is simply to hunt for them. In hunting
for them, first we learn that many of the objects aren't going to hit the
Earth. In fact, none of them that we've found so far, that are large, are
going to hit the Earth," Chapman said.

Chapman said that while the impact hazard from large objects is real, it is
very unlikely to happen in our lifetimes. He remarked that he wasn't sure
the logic is in favor of ramping up efforts to search for every object that
might cause a smaller, Tunguska-like blast.

Underscoring the demolition stemming from a mega-Earth impactor, Chapman
said that, indeed, the "potential consequences are horrific, exceeding any
other natural hazard and roughly that of an all-out nuclear war." Nations do
have the wherewithal to avert a threatening impact, he said.

"Unlike the dinosaurs, the big picture is that we do have the capability and
intelligence to protect ourselves from this threat. The questions are...will
we take a gamble and submit to fate? Or do we undertake a measured,
rationale response? The first element is to educate ourselves and our
leaders about this issue, and rationally decide what fraction of our budget
should be devoted to protecting our planet," Chapman said.

Lingering hazard

Chapman emphasized that once all the asteroids have been located, comets
remain a "lingering hazard." They can creep into our solar system on short
notice.

Comet Hale-Bopp -- slipping by Earth in 1997 -- was likely 100 times more
massive than the object that wiped out the dinosaurs, Chapman explained.

"It was a big one, and it was only discovered something like a year before
it came in," Chapman said.

There is a current dilemma, the planetary scientist added.

In the event a hostile object is on a collision course with our home planet,
who does the astronomer call? Furthermore, the existing infrastructure
within which to communicate, then do something about the troubling impactor,
is very disorganized, Chapman emphasized.

"Astronomers are just learning how to communicate. But the relevant agencies
are not prepared to listen and act," Chapman said.

Round-trip rockfest

A top priority on the "to do" list of future space projects is a "hands-on"
near-Earth asteroid (NEA) mission. That's the belief of planetary scientist,
Daniel Durda of the Southwest Research Institute in Boulder, Colorado.
Asteroids are "tempting targets" for human explorers, he said.

Durda points out that there are about 10,000 near-Earth asteroids larger
than 33 feet (10 meters) across - and they are easier to reach from an
orbital energy standpoint than the surface of the Moon. "That suggests that
there should be many launch opportunities over the course of any given
year," he said.

One prime piece of unreal estate for human exploration, Durda said, is
asteroid 1991 VG. It passed about 1.2 lunar distances of Earth in December
of 1991. The orbit of this tiny world is very Earth-like.

Outbound and return trek times involving asteroid 1991 VG would each be in
the neighborhood of 15 days. Once at the body, a crew could study the space
rock for 30 days. The entire mission would take about two months, "well
within our experience base when you consider the stay times that we become
accustomed to for International Space Station (ISS) expeditions," Durda
said.

"It turns out that during the entire mission, the crew would never venture
farther from Earth than about 4.5 lunar distances. The Earth would never
appear smaller in the sky than the full Moon appears to us from here on
Earth! That's not such a daunting trip at all," Durda remarked.

Cling ons

Once a crew is on-location at an asteroid, it's not a cakewalk.

Because of the very low surface gravity of a small asteroid -- even one
under a mile (1-kilometer) in diameter sports a gravity only 1/28000th that
of Earth -- operations in the vicinity of a NEA would be more like docking
with and spacewalking around the ISS.

In that sense, Durda said, the experience base we are gaining with space
station hookups and crew members moving about outside the complex are
invaluable. Also, the rapidly changing orbital day-night lighting conditions
are similar to what an astronaut would experience on a small, rapidly
rotating asteroid.

"However, we still need to learn a great deal about interacting with the
surface of a small asteroid in essentially non-existent gravity," Durda
said. For instance, he added, how will electrostatically charged dust from
an asteroid's surface cling to space suits and equipment? How might we need
to alter or redesign maneuvering backpacks for extended transportation and
navigation around the rocky world?

There are many benefits from visiting a giant hunk of space flotsam.

"The NEAs provide the ideal means to expand our experience base and our
presence beyond low-Earth orbit and beyond the Earth-Moon system," Durda
said. Asteroid journeys would provide a bonanza of data useful to asteroid
and meteorite science.

"Development of an asteroid visit capability will also give us invaluable
data and skills to develop credible deflection and or destruction
technologies for dealing with the asteroid impact hazard," Durda concluded.

Copyright 2002, Space.com

===========
(2) SCIENTISTS STUDY DEFENDING EARTH AGAINST ASTEROIDS

>From Scripps Howard News Service, 3 June 2002

http://www.knoxstudio.com/shns/story.cfm?pk=ASTEROIDS-06-03-02&cat=AS

By MICHAEL WOODS
Toledo Blade
June 03, 2002

The federal government is summoning the world's top scientists to an urgent
conference this summer to plan defenses against an attack that could wipe
out an American city or disrupt the whole country's infrastructure.

No, it's not global terrorism.

The scientists will map ways to combat an asteroid attack, a cosmic sucker
punch like the collision that killed the dinosaurs 65 million years ago and
flattened a Siberian forest in 1908.

While the world's attention is focused on the real threat of terrorism, the
theoretical asteroid menace has been garnering a surprising amount of
behind-the-scenes attention.

Britain's Royal Astronomical Society hosted an international meeting of
experts on the asteroid impact threat in December. In January the world's
astronomers petitioned Australia's government to fund a special
asteroid-detecting telescope. In February NASA announced the "Workshop on
Scientific Requirements for Mitigation of Hazardous Comets and Asteroids,"
which will be conducted in Washington in September. In March, NASA activated
"Sentry," a new system to monitor s near-Earth objects (NEOs) and assess
their threat to Earth.

NEOs are small objects - asteroids and certain comets - that orbit in the
solar system relatively close to Earth and could one day collide with Earth.

"We've had a couple of close shaves during the past few months," said Dr.
Brian G. Marsden, with the Harvard-Smithsonian Center for Astrophysics in
Cambridge, Mass.

One asteroid caused public jitters when discovered March 12. Named 2002 EM7,
it came from the direction of the sun - an astronomical blind spot where
objects are hidden in the sun's glare.

Astronomers didn't detect 2002 EM7 until four days after it came within
288,000 miles of Earth, which they regarded as a close encounter.

The asteroid was about 200 feet in diameter - big enough to fill two-thirds
of a football field - and could have flattened a city, unleashing the energy
of a 5-megaton nuclear bomb.

"I think Mother Nature has given us yet another wake-up call," said Dr.
Donald K. Yeomans of NASA. "Objects the size of 2002 EM7 pass as close as
this one did every two weeks or so. We just haven't found them all yet."

Another scare occurred in January, when a 1,000-foot-diameter asteroid came
within 375,000 miles of Earth. Astronomers detected the mountain-sized rock,
named 2001 YB5, only a few weeks earlier.

Dr. Richard P. Binzel, with the Massachusetts Institute of Technology, said
the public can expect more close-encounter stories. "It is simply a matter
of our increasing prowess in detection that objects like 2001 YB5 are now
being seen," Binzel said.

NASA, the European Space Agency, and universities have been monitoring space
for NEOs and tracking their paths with great precision. Astronomers are
detecting more and more asteroids that sped by unnoticed in the past.

"The goal is to track NEOs well in advance of any Earth-threatening
encounters so that a mitigation plan could be put into effect," said
Yeomans, with NASA's Jet Propulsion Laboratory in Pasadena, Calif. "No
objects that we know about threaten us, and we're well on the way to finding
the majority of the entire population of large NEOs."

Finding the smaller ones, like 2002 EM7, will take years longer and require
bigger telescopes than those used in asteroid search-and-tracking efforts,
he added.

"That said, NEOs are not something to lose sleep over," Yeomans added.

Dr. Gareth Williams of the Smithsonian center cited the importance of
detecting small asteroids when they're visible - not hidden in the sun's
glare - so they can be tracked and monitored.

Objects the size of 2002 EM7 make similarly close approaches to Earth
several times a month, Williams said. They hit Earth every 30 to 100 years,
he said, but usually burn up in the atmosphere.

Such impacts, however, create an "air-burst," or powerful shock wave that
can cause considerable localized damage on the ground below.

"The 1908 Tunguska event was an example of the local damage that would occur
under and around the air-burst of such an object," Williams explained,
referring to the incident near the Stony Tunguska River in Siberia in which
a mysterious airborne explosion - now believed to be an asteroid impact -
leveled a section of forest half the size of Rhode Island. Scientists
estimate it caused as much destruction as a 15-megaton nuclear bomb.

"Impacts by such objects are not likely to cause major loss of human life,"
Williams asserted. "About 70 percent of the world's surface is water, and
much of the land mass is either uninhabited or very sparsely populated."

Using the 1,000-foot diameter 2000 YB5 asteroid as an illustration, Binzel
said there is about a 1-in-10,000 chance of an impact with Earth each year
or a 1-in-100 chance of an impact sometime during the 21st century.

Binzel said 2000 YB5 and 2002 EM7 were essentially no-risk asteroids.

"Most of these chances are in the 1-in-a-million or 1-in-a-billion range,"
Marsden said. "And it is very likely that that, as we make further
observations, the impact probabilities will become precisely zero."

The only nightmare near-Earth object known today is 2002 CU11, which is
about 2,000 feet in diameter and has a 1-in-9,000 chance of hitting Earth on
Aug. 31, 2049. It was discovered in February. Scientists think there are at
least eight other Earth-impact possibilities between 2032 and 2096.

NASA described its September conference as "urgent" because scientists
believe it will take 70 years to develop mitigation technology and learn to
use it against an Earth-threatening object. Experts will propose and discuss
specific countermeasures in September.

"The more we know about NEOs, and the longer the advance notice of possible
impacts, the better off we are," said Marsden. "We can do it," he added.
"Pity the poor dinosaurs, who couldn't."

On the Web: Forecasts of known asteroid encounters are easily available on
the Internet as well, including sites like the NASA-affiliated
www.spaceweather.com.

(Distributed by Scripps Howard News Service, http://www.shns.com .)

===============
(3) STUDY: "PERMIAN-TRIASSIC MASS EXTINCTION NO CAUSED BY COSMIC IMPACT"

>From CNN, 6 June 2002
http://www.cnn.com/2002/TECH/science/06/06/volcanic.extinction.ap/index.html

WASHINGTON (AP) -- A massive flow of molten rock, bubbling to the surface
and spreading more than a mile deep over an area half the size of Australia,
may have killed up to 90 percent of all animal species on Earth some 250
million years ago, a study suggests.

The study shows that the flood of molten rock that created what is known as
the Siberian Traps in Russia was almost twice as big as previously believed
and could have continued for thousands of years, changing the climate of the
entire planet.

The researchers, a group of United Kingdom and Russian scientists, say in a
report to appear Friday in the journal Science that such an eruption of
flood basalt would have filled the atmosphere with a choking concentration
of sulfur dioxide, carbon dioxide and other gasses, making it difficult for
any species to survive.

Samples from the lava flow have been age-dated at about 250 million years.
Other studies have shown during this same period the Earth experienced its
most extensive extinction crisis -- a die-off that killed at least 90
percent of ocean species and more than 70 percent of land creatures.

Called the Permian-Triassic extinction, it is a key event in the history of
the planet. It was followed by the rise of the dinosaurs, the animal species
that dominated the Earth, until they too went extinct about 65 million years
ago.

In the study, the researchers analyzed samples drilled from deep below the
floor of a basin beside the known Siberian Traps. They found that the basin
was underlain with the same type and age of lava that created the Traps.

This means that the flood of lava that formed the Traps was at least twice
as massive and lasted perhaps twice as long as previously believed, they
said.

Asteroid theory

Such a large volume of lava spewing to the surface over hundreds of
thousands of years would inject millions of tons of chemicals into the
atmosphere, causing long-lasting changes in the climate and an ecological
collapse, they said.

"The larger area of volcanism strengthens the link between the volcanism and
the end-Permian mass extinction," the authors say in Science.

Some earlier studies have suggested that the Permian-Triassic extinction was
caused by an asteroid striking the Earth and wiping out much of life with a
sudden, single stroke.

But the evidence from the new study points toward a prolonged extinction
event, stretching over hundreds of thousands of years.

Peter D. Ward, professor of geological sciences and a paleontologist at the
University of Washington, said the United Kingdom and Russian study
reinforces what is becoming a widely accepted view of many other
researchers.

"It looks like the Earth was getting multiple levels of extinction," said
Ward. He said chemical studies of ancient geology suggest that plant
productivity was impacted "over and over again" during the period around the
Permian-Triassic boundary.

'Not a single event'

He said phased cycles of extinction, as evidenced in the geological record,
are compatible with a massive, prolonged flood of molten basalt.

"We don't see all of the basalt coming out at once, as a steady stream,"
said Ward. "It was not a single event" such as an asteroid impact.

This is in contrast to the extinction event that killed the dinosaurs. Ward
said many different studies show that an asteroid did deliver "a one-time
hit" on the Earth that caused rapid changes that snuffed out the dinosaurs.

Marc K. Reichow of the University of Leicester in the United Kingdom was
lead author of the study. Other researchers were from the Scottish
Universities Environmental Research Center in Scotland, and from the
Institute of Geochemistry and the Institute of Geology Oil and Gas, both in
Russia.

Copyright 2002 The Associated Press.

=============
(4) FORGET NEO IMPACTS: "VOLCANOES KILLED OFF PERMIAN SPECIES"

>From Nature, 7 June 2002
http://www.nature.com/nsu/020603/020603-6.html

Lava flow twice the size of Europe covered Siberia 250 million years ago.

PHILIP BALL

We knew it was big - but not this big. Geologists now suspect the massive
eruption of lava in Siberia 250 million years ago was at least twice as
large as they'd thought. This makes it even more likely to have caused the
biggest extinction the world has ever seen.

The Permian period ended with the extinction of 85% of all ocean creatures
and 70% of land ones - a toll three times greater than the extinction that
killed off the dinosaurs at the end of the Cretaceous, 65 million years ago.

At the same time Siberia was flooded with at least a million cubic
kilometres of lava. Scientists have wondered for years whether the two were
related.

Very probably, say Andrew Saunders of the University of Leicester in the UK
and co-workers. They have found that the Siberian flood basalt province
extends much farther west than previously analyses suggested.

Lava, arising from deep within the Earth, brings up with it huge amounts of
gases such as sulphur dioxide, carbon dioxide and hydrogen fluoride.
Released into the atmosphere, these gases can drastically change
environmental and climatic conditions. Sulphur dioxide, for instance, is
poisonous and creates acid rain. Carbon dioxide is a greenhouse gas.

Ash and sulphur gases can also create airborne particles that block out
sunlight, cooling the Earth's surface. There is evidence that sea level
plummeted at the end of the Permian - possibly as a result of an expansion
of the ice sheets.

No one knows exactly how big these effects might have been, or how they
might have affected life on the planet. But they could have caused the kind
of disruptions to ecosystems that tip species towards extinction.

Under Traps

The Siberian Traps are a plain of volcanic rock stretching for over 1,000 km
from north to south. Centred around the city of Tura, the Traps cover around
2 million square kilometres: more than the entire land surface of Europe.

Saunders's team bored holes more than 4 km deep into the West Siberian
Basin, to the west of the Traps. The researchers found yet more basalt
hidden deep below these rocks.

They calculate that the buried basalt is 249 million years old - the same
age as that in the Traps. It is more material from the Siberian Traps, they
reason, which later became flooded and buried.

The researchers estimate that the buried basalt covers at least as great an
area, and contains as great a volume, as the exposed Siberian Traps to the
east. In other words, the vast outpouring of lava at the end of the Permian
was twice as extensive as previously thought, maybe even more.

Cloud cover

A more speculative explanation for mass extinctions has also been put
forward this week. Hans Jorg Fahr of the Bonn Institute of Astrophysics and
Extraterrestrial Research in Germany and colleagues propose that, on its
orbit around the centre of the Galaxy, our Solar System passes once every 60
million years or so through dense clouds of interstellar gas. This, the
researchers believe, could disrupt the solar wind, the stream of charged
particles from the Sun.

The solar wind shields the Earth from cosmic rays. If the wind weakens, more
cosmic rays break through into the Earth's atmosphere and collide with air
molecules to produce electrically charged fragments. These fragments trigger
the formation of cloud droplets. The resulting change in cloud cover could
alter climate in ways that lead to mass extinctions, Fahr and his team
reason.

But it is unclear whether the effects of greater cloudiness could be that
dramatic, and it is far from certain that mass extinctions really show a
60-million-year periodicity.

References
Reichow, M. K. et al. 40Ar/39Ar dates on basalts from the West Siberian
Basin: doubled extent of the Siberian flood basalt province. Science, 296,
1846 - 1849, (2002).

Copyright 2002, Nature News Service / Macmillan Magazines Ltd 2002

================
(5) FLOOD BASALT: BIGGER AND BADDER

>From Science, 7 June 2002
http://www.sciencemag.org/cgi/content/full/296/5574/1812

Paul R. Renne [HN17]*

Flood volcanism [HN1] is an episodic process whereby vast amounts of mass
and energy are transferred from Earth's interior to its surface within a
relatively short time. Such  events have occurred about a dozen times during
the last several hundred million years. There is increasing geochronological
[HN2] evidence that in each of these events, the magma [HN3] was generated
and erupted within 1 to 3 million years or so. The implied magma production
rate, on the order of 106 km3/year, is much higher than in Earth's main
magma-producing environments at the boundaries between lithospheric plates.

Increasingly, Earth scientists are trying to establish the causes and
consequences of flood volcanism. The Siberian Traps [HN4] have played a
central role in shaping thought on the problem.

More than 20 years ago, Morgan [HN5] (1) posited that this massive mantle
belch might have been the first manifestation of a still-active magma source
(hot spot) represented by  a volcanic island, Jan Mayen [HN6], in the North
Atlantic. A generalized theory soon linked flood basalts to hot spots
created  by buoyant, superheated mantle plumes, which were inferred to play
a dynamic role in the rifting apart of continents [HN7] (2). A leading
alternative to these "plume impact" models holds that flood volcanism
results when rifting of the lithosphere causes  decompression of the mantle,
allowing it to melt and rise buoyantly without requiring anomalous heating.

The rifting that precedes decompression melting in the latter model cannot
happen quickly for mechanical reasons: The lower  lithosphere is ductile and
does not break rapidly under extension. Pure decompression melting therefore
seems less consistent with the observed rapidity of the eruptions than does
the plume impact model. On the other hand, there is evidence that crustal
extension predates volcanism in some cases, which suggests that at least
some aspects of the decompression model are valid. But what initiates
extension, if not the dynamic consequences of plume impact? One possibility
is edge-driven convection (3),  hypothesized to originate from
discontinuities in lithospheric thickness and properties.

Besides establishing the brevity of flood volcanic events, geochronology has
played a key role in defining the vast provinces  wherein they occur. A
recent example is the central Atlantic magmatic province (CAMP) [HN8], whose
200-million-year-old remnants are now scattered across eastern North
America, northeastern South America, western Africa, and western Europe. It
had been hypothesized that CAMP's remnants formed a single contiguous
province before the opening of the central Atlantic (4), but it was only
through precise dating of the dispersed fragments that identification of an
extensive flood basalt province was confirmed (5).

Similarly, new dating results reported by Reichow et al. [HN9] on page 1846
of this issue (6) document the subsurface extent of the Siberian Traps
nearly 1000 km westward from the previously known limits of the province.
The authors have analyzed drill-core samples from the West Siberian Basin
[HN10] (WSB). The new dating provides the first definitive evidence linking
them to the same magmatic event.

Using the 40Ar/39Ar method [HN11], Reichow et al. (6) show that the WSB
lavas are indistinguishable in age from those to the  east, previously dated
at 250 million years by similar methods (7). The new results suggest a total
areal extent of 3.9 x 106 km2 for the Siberian Traps. The total volume of
magma represented by this enlarged province is difficult to estimate, but 2
x 106 to 3  x 106 km3 is probable, clearly qualifying the Siberian Traps as
the largest (by volume) known continental flood basalt province.

The WSB underwent rifting during the late Paleozoic or early Mesozoic (about
300 to 200 million years ago), bearing out the  general relationship between
extension and flood volcanism. Unfortunately, as in many other cases,
existing data appear equivocal on the crucial question
of whether extension began before or after the onset of volcanism.
Establishing the relative ages of these events should now become a priority.

Upward revision of the dimensions of flood volcanic provinces will doubtless
continue as research progresses. Recent work (8) shows that magmatism of
essentially the same age as the Siberian Traps occurred as far south as
central Kazakhstan, and a swath of contemporary magmatic activity may even
extend semicontinuously from there to south of Lake Baikal. These complexes
appear to represent the roots of silicic volcanic centers, whose explosive
eruptions would have provided a mechanism for transporting volcanogenic
gases [HN12] into the upper atmosphere.

These increasing size estimates have important implications for the
environmental consequences of flood volcanic events. The more voluminous a
magma system is, the more likely it is to generate large quantities of
climate-modifying gases such as CO2 and SO2. The amounts of such gases
actually delivered to the atmosphere by flood volcanism remain difficult to
quantify, but there is little doubt that the effects could be significant.
The synchrony between flood volcanic events and mass extinctions  [HN13] in
the geologic record has been noted for years. For the three biggest events
(the Siberian, CAMP, and Deccan traps [HN14]), a temporal correlation with
the most severe extinctions at the end of the Permian, Triassic, and
Cretaceous periods, respectively, is firmly established.

The empirical connection between major flood volcanism and severe mass
extinctions is all the more intriguing in light of hints of evidence of
large meteor impacts coincident with these events. The evidence is strongest
at the end of the Cretaceous. The latest hint suggests that
CAMP and the extinction at the end of the Triassic may have been coincident
with an impact [HN15] (9), although the impact evidence in this case is
permissive rather than indicative.

To some Earth scientists, the need for a geophysically plausible unifying
theory linking all three phenomena is already clear. Others still consider
the evidence for impacts coincident with major extinctions too weak, except
at the end of the Cretaceous. But few would dispute that proving the
existence of an impact is far more challenging than documenting a flood
basalt event: It is difficult to hide millions of cubic kilometers of
lavas--even, as shown by Reichow et al. (6), when they are buried beneath 2
km or more of sediments in Siberia.

References and Notes

1.W. J. Morgan, in The Sea, C. Emiliani, Ed. (Wiley-Interscience, New York,
1981), vol. 7, pp. 443-475.
2.M. A. Richards, R. A. Duncan, V. E. Courtillot, Science 246, 103 (1989)
[GEOREF] [JSTOR].
3.S. D. King, D. L. Anderson, Earth Planet. Sci. Lett. 160, 289 (1998)
[ADS].
4.V. Courtillot, Isr. J. Earth Sci. 43, 255 (1994) [GEOREF].
5.A. Marzoli et al., Science 284, 616 (1999).
6.M. K. Reichow et al., Science 296, 1846 (2002).
7.Originally dated at about 248 Ma (10), these ages were revised after
recalibration of a standard (11).
8.J. O. Lyons et al., J. Geophys. Res., in press.
9.P. E. Olsen et al., Science 296, 1305 (2002).
10.P. R. Renne, A. R. Basu, Science 253, 176 (1991) [GEOREF] [JSTOR].
11.P. R. Renne et al., Science 269, 1413 (1995) [GEOREF] [JSTOR].

The author is at the Berkeley Geochronology Center, Berkeley, CA 94709, USA,
and in the Department of Earth and Planetary Science, University of
California, Berkeley, CA 94720, USA. E-mail: prenne@bgc.org

Volume 296, Number 5574, Issue of 7 Jun 2002, pp. 1812-1813.
Copyright © 2002 by The American Association for the Advancement of Science.
All rights reserved.

=============
(6) FORGET NEO IMPACTS: "COSMIC STORM KILLED OFF DINOSAURS"

>From Andrew Yee <ayee@nova.astro.utoronto.ca>

Universität Bonn
Bonn, Germany

Contact:
Professor Hans Jörg Fahr
Institute of Astrophysics and Extraterrestrial Research
hfahr@astro.uni-bonn.de, ++49-228-733677

Dr. Michael Bird
Institute of Radio Astronomy
++49-228-733651

4 June 2002

Protective Storm in Space -- a new explanation for the death of the
dinosaurs

A shower of matter from space millions of years ago could have led to
drastic changes in the Earth's climate, followed by the extinction of life
on a massive scale, which also killed off the dinosaurs. This at least is a
theory put forward by scientists from the University of Bonn. Normally, the
solar wind acts as a shield against showers of cosmic particles, which
prevents too many energy-rich particles from raining down on our atmosphere.
Since 1997 scientists from Bonn, funded by the German Research Council
(Deutsche Forschungsgemeinschaft or DFG), have been examining how and
why this gigantic shield works.

They were the undisputed masters of a whole geological era until they
suddenly disappeared 65 million years ago. "Perhaps Earth just became too
damp and too cold for dinosaurs at that time," Professor Hans Jörg Fahr from
the Bonn Institute of Astrophysics and Extraterrestrial Research surmises.
The reason for the sudden change in climate could have been excessive
pressure on our cosmic umbrella.

The solar system does not stand still, in fact it orbits the centre of the
Milky Way once every 250 million years. In the process it also passes
through dense clouds of interstellar matter, which causes problems for the
solar wind and thus for the Earth. Whereas the solar wind normally protects
the Earth from a hail of interstellar particles like a huge bullet-proof
vest, there are then suddenly up to a hundred times more particles raining
down into the earth's atmosphere at enormous speeds. On impact they smash
the air molecules into electrically charged fragments. These function as
condensation nuclei on which droplets of water form. "The result is dense
cloud cover with greater precipitation and sinking temperatures," says Professor
Fahr, who bases his remarks on research worldwide.

Prof. Fahr and his colleagues Dr. Horst Fichtner and Dr. Klaus Scherer have
shown that every 60 million years on average the solar system passes through
dense clouds of matter, which could trigger off this sort of climate shock.
Prof. Fahr adds: "At roughly these intervals many species suddenly became
extinct." Research by other teams which have examined the link between cloud
cover and solar activity has shown that cosmic factors could have had a dramatic impact
on our climate on several occasions in the past. "The less solar activity there is
and therefore the less protection there is from the solar wind, the more
cosmic particles reach the earth, and the more clouds form on earth," is how
Prof. Fahr sums up the process.

Experts call the electrically charged particles which our sun emits "solar
wind". They race through our solar system at a velocity of up to 800
kilometres per second, with a range extending a hundred times as far as the
distance between the Earth and the sun. "Every eleven years the sun's
activity and therefore the solar wind reaches a maximum. At these times, for
example, there is an increase in the frequency of the colourful auroras, when particles of
the solar wind are captured by the Earth's magnetic field and are then catapulted into the
upper atmosphere, where they make the oxygen glow," Dr. Michael Bird from
the Institute of Radio Astronomy explains. During particularly active
phases, e.g. during big solar eruptions, the shower of particles can even
interfere with short-wave reception, disrupt orbiting satellites or even
"switch off" whole power stations.

"In Bonn we are especially interested in how the solar wind reaches its high
velocities," Dr. Bird explains. "These cannot be explained solely by the
enormous heat in the sun's atmosphere." There seems, in other words, to be
another source of energy which catapults the particles into space. The hot
favourites for Bonn's astrophysicists are exotic waves of magnetic fields in
the corona, the "sun's atmosphere" which are amplified while they are
expanding and then give the particles the necessary momentum. "We are
tracking these waves by using radio astronomy," the US physicist adds.

Incidentally, cosmic weather might also be a decisive factor in the speed of
evolution. The cosmic rays from which we are protected by the solar wind are
so full of energy that they can change the DNA of living beings. If the
solar wind's shield effect is too weak, i.e. the Earth's protective mantle
is thin, within a short space of time this results in more mutations, which
are the driving force of the evolution of life.

Notes for editor:

Pictures to this press release are by 2 p.m. available in the web:
     http://www.uni-bonn.de/Aktuelles/Pressemitteilungen/177_02.html

=============
(7) PERMIAN IMPACT CAUSED LARGEST MASS EXTINCTION ON EARTH

>From Space Daily, 31 August 2001
http://www.spacedaily.com/news/life-01ze.html

Boulder - August 30 2001
What actually ended the Permian Period some 251 million years ago? Most
Earth scientists think gradual sea fall, climate change, oceanic anoxia, and
volcanism were the causes.
But that's not so. A group of geologists working in southern China found
evidence that it was an asteroid or a comet that smacked our planet,
exploded, and then caused the most severe biotic crisis in the history of
life on Earth.

In the September issue of Geology, Kunio Kaiho from Tohoku University
reports their findings of a remarkable sulfur and strontium isotope
excursion at the end of the Permian, along with a coincident concentration
of impact- metamorphosed grains and kaolinite and a significant decrease in
manganese, phosphorous, calcium, and microfossils (foraminifera).

Their discoveries at Meishan (Mei Mountain) suggest that an asteroid or a
comet hit the ocean at the end of the Permian, triggered a rapid and massive
release of sulfur from the mantle to the ocean-atmosphere system, swooped up
a significant amount of oxygen, precipitated acid rain, and possibly set off
large-scale volcanism.

"Understanding the cause of this event is important because it represents
the largest mass extinction," Kaiho said, "and it led to the subsequent
origination of recent biota on Earth."

Kaiho discovered the significance of the site when he took samples from it
in 1996 and again in 1998. He plans to investigate other evidence of impact
events.

"We would like to clarify paleoenvironmental changes and causes of the end
Permian mass extinction in different places and of the other mass
extinctions which occurred during the past 500 million years: end
Ordovician, Late Devonian, and end Triassic," he said.

===========
(8) AN EXTRATERRESTRIAL IMPACT AT THE PERMIAN-TRIASSIC BOUNDARY?

>From Science, Volume 293, Number 5539, Issue of 28 Sep 2001, p. 2343.

An Extraterrestrial Impact at the Permian-Triassic Boundary?

   Becker et al. (1) presented geochemical evidence that suggests that
   the largest mass extinction in Earth history, at the Permian-Triassic
   boundary (PTB) 250 million years ago (Ma), coincided with an
   extraterrestrial impact comparable in size to the one that likely
   caused the end-Cretaceous extinctions 65 Ma (2). Although Becker et
   al. analyzed material from sections in Hungary, Japan, and China, the
   Hungarian section yielded no extraterrestrial signature, and their
   identification of the PTB in the Japanese section is questioned in the
   accompanying comment by Isozaki (below). Thus, only their analyses of
   the Chinese section provide hitherto uncontested evidence for an
   impact at the boundary--in the form of data on the abundance and
   composition of fullerenes in the "boundary clay," a volcanic ash layer
   called Bed 25 at Meishan, China (3). Although fullerenes may be purely
   terrestrial [see, e.g., (4)], Becker et al. report that the fullerenes
   from the Meishan ash carry extraterrestrial noble gases in the cage
   structure, rich in 3He and with distinctive 3He/36Ar and 40Ar/36Ar
   ratios, and that this signature therefore derived from a bolide
   impact. Here, we report that we are able to detect fullerene-hosted
   extraterrestrial 3He neither in aliquots of the same Meishan material
   analyzed by Becker et al., nor any in samples of a second Chinese PTB
   section, and that we thus find no evidence for an impact.

   Becker et al. reported helium in bulk rock and in fullerenes extracted
   from Meishan Bed 25 following acid demineralization. Their two
   aliquots of bulk rock yielded 0.43 and 0.58 pcc/g (10 - 12 cc g - 1 at
   standard temperature and pressure) of 3He. From 40 g of rock, Becker
   et al. extracted 14 µg of fullerene that yielded very high 3He
   concentrations, implying that fullerene-hosted helium accounted for at
   least 0.052 pcc/g of the 3He in Bed 25; this number could be higher,
   because Becker et al. provided no indication of fullerene extraction
   efficiency.

   We first analyzed 15 aliquots of bulk rock from Bed 25, provided by
   S. Bowring to be representative of the material he supplied to Becker
   et al. Samples were initially dried in an oven for 2 hours at ~90 to
   100 °C to drive off adsorbed water. Based on stepped-heating results
   on fullerenes (1), no 3He would have been lost during sample drying.
   We then gently powdered 150 g of rock by hand with a mortar and pestle
   and thoroughly homogenized the sample. Ten aliquots (~350 mg each)
   were drawn from this homogenized powder; the remaining five aliquots
   were taken from several different clumps of the material to assess
   spatial heterogeneity. Samples were fused under vacuum at 1400°C
   following procedures reported earlier (5), except that the acetic acid
   step, designed to remove CaCO3, was not used on these carbonate-poor
   rocks. None of these samples yielded a significant amount of 3He (Fig.
   1): The mean of the 15 runs was 0.005 pcc/g, and the maximum for any
   single aliquot was only 0.01 pcc/g. We obtained similar results from
   six samples of the stratigraphically equivalent bed at Shangsi, China
   (also provided by Bowring). Hence, we obtained 3He concentrations from
   bulk rock samples that were a factor of 45 to 150 lower than those
   reported by Becker et al. To ensure that we were quantitatively
   extracting all the He at 1400°C, we outgassed a single sample at
   1800°C after fusion at 1400°C; no additional 3He was released.

   Fig. 1. He isotope data for Chinese PTB samples.
   Filled symbols, Becker et al. (1); open symbols, this study.

   We then demineralized a 16 g aliquot of Meishan Bed 25, following the
   same HF-BF3 digestion procedure (6) used by Becker et al. This residue
   contained only 0.003 pcc of 3He per gram of starting material. Because
   the demineralized residue does not contain significant 3He,
   fullerene-hosted 3He within this residue cannot be significant either,
   so we did not isolate fullerene for noble gas analysis. This
   experiment places an upper limit on the fullerene-hosted 3He in Bed
   25 that is a factor of 15 lower than the concentration reported by
   Becker et al. (1).

   The helium we obtained from Bed 25 samples is reasonable for a
   250-million-year-old volcanic ash bed. Large inter-aliquot variability
   in 4He content and the survival of most 4He through HF
   demineralization (Fig. 1) suggest that accessory zircons, known to
   exist in Bed 25 (3), control the distribution of this isotope. The 3He
   concentration and 3He/4He ratio (average <0.003 RA) of Bed 25 are
   lower than we obtained from several hundred deep-sea carbonate
   sediments [see, e.g., (5)] and are at the low end of the range
   expected for purely terrestrial radioactive decay processes (7). The
   dearth of 3He from interplanetary dust particles (IDPs)--not to be
   confused with a fullerene-hosted impact signature--is not surprising,
   because Bed 25 is a volcanic ash and was likely deposited quickly.

   We thus find no evidence for the impact-derived 3He reported by Becker
   et al. Our analytical technique for 3He is as sensitive and precise
   [see details in (5)] as that used by Becker et al., so the discrepancy
   between our results and theirs is probably not analytical in origin.
   Sample heterogeneity is also an unlikely explanation: Although Becker
   et al. found substantial 3He in all three aliquots they analyzed (a
   total of 41 g of rock), we were unsuccessful in detecting
   extraterrestrial 3He in any of our 22 aliquots (150 g of homogenized
   Bed 25 in 10 aliquots, 1.5 g of spatially distributed spot samples in
   five aliquots, and 16 g of demineralized rock in one aliquot from
   Meshian, as well as 2 g of rock in six aliquots from three samples of
   the Shangsi P-Tr boundary bed).

   Without confirmation of fullerene-hosted 3He in Bed 25, both the
   occurrence of an extraterrestrial impact and the cause of the mass
   extinction at the PTB must remain open questions.

                                                             K. A. Farley
                                                         S. Mukhopadhyay
                                               Division of Geological and
                                                       Planetary Sciences
                                                                MS 170-25
                                       California Institute of Technology
                                                  Pasadena, CA 91125, USA
                                           E-mail: farley@gps.caltech.edu

REFERENCES

   1. L. Becker, R. J. Poreda, A. G. Hunt, T. E. Bunch, M. Rampino,
   Science 291, 1530 (2001).
   2. L. W. Alvarez, W. Alvarez, F. Asaro, H. V. Michel, Science 208,
   1095 (1980).
   3. S. A. Bowring et al., Science 280, 1039 (1998).
   4. D. Heymann et al., Geol. Soc. Am. Spec. Pap. 307, 453 (1996).
   5. S. Mukhopadhyay, K. Farley, A. A. Montanari, Geochim. Cosmochim.
   Acta 65, 653 (2001).
   6. T. L. Robl and B. H. Davis, Org. Geochem. 20, 249 (1993).
   7. J. N. Andrews, Chem. Geol. 49, 339 (1985).
   27 April 2001; accepted 17 August 2001

   Becker et al. (1) reported an anomaly in 3He trapped in fullerene from
   PTB rocks from Japan and China, which in turn suggested a possible
   extraterrestrial impact as the cause of the PTB mass extinction.
   Although the approach of using the 3He signature appears promising,
   the stratigraphy of the Sasayama section in Japan poses a major
   problem that is fatal to their conclusion: The PTB horizon is missing
   in this section, and the "3He-enriched" sample they analyzed has
   actually come from at least 0.8 m (and possibly much further) below
   the PTB.

   Owing to absence of good index fossils, the Sasayama section is dated
   by correlation with other sections. The PTB sections of deep-sea chert
   facies have been examined in more than ten sections in Japan (2, 3);
   all showed a constant lithostratigraphy that comprised, from bottom to
   top, (i) Late Permian bedded chert, (ii) latest Permian siliceous
   claystone or shale, (iii) boundary black organic claystone, (iv) Early
   Triassic siliceous claystone, and (v) late Early to Middle Triassic
   bedded chert. The lower chert and siliceous claystone are
   characterized by Chanhsingian (late Late Permian) radiolarians such as
   Neoalbaillella optima and Albaillella triangularis (4), and the upper
   siliceous claystone and chert contain distinct Early Triassic forms.
   The central black claystone, less than 5 m thick, yields only
   ill-preserved microfossils and thus is not dated precisely.
   Nevertheless, these data indicate that the PTB horizon is somewhere
   within the black claystone (2), not in the lower siliceous claystone.
   Thus the "3He-enriched" sample of Becker et al. (1) was clearly
   collected from the Late Permian interval at least 0.8 m below the PTB.

   Making the situation worse, this section is cut in the middle by a
   fault, with gouge and chert breccia [described as sheared black shale
   in figure 2 of (1)] that has removed beds nearly 20 to 30 m thick
   between the lower siliceous claystone and the upper chert. Thus, not
   only does the section lack the PTB horizon, but this faulting has
   removed an additional, undetermined interval of time between the
   claimed "3He-enriched" sample and the PTB. In any case, the Permian
   radiolarians and conodonts survived even above this "3He-enriched"
   horizon up to the top of the siliceous claystone. This suggests that
   the alleged impact event did not terminate such cosmopolitan marine
   biota that flourished throughout the Permian and finally disappeared
   at PTB.

   At least for confirming the background absence of 3He in adjacent
   horizons immediately above and below PTB, Becker et al. should have
   checked better PTB sections and used more samples collected following
   a double-blind protocol. Becker et al. also reported a similar 3He
   spike from Bed 25 (a volcanic tuff of terrestrial origin) immediately
   below PTB in the Meishan section in China. Because the "3He-enriched"
   sample from Sasayama is significantly older than Meishan Bed 25, they
   cannot have been from the same impact event.

                                                            Yukio Isozaki
                                Department of Earth Science and Astronomy
                                                      University of Tokyo
                                            Komaba, Tokyo 153-8902, Japan

REFERENCES

   1. L. Becker, R. J. Poreda, A. G. Hunt, T. E. Bunch, M. Rampino,
   Science 291, 1530 (2001).
   2. Y. Isozaki, Science 276, 235 (1997).
   3. Y. Kakuwa, Palaeogeogr. Palaeoclimatol. Palaeoecol. 121, 35 (1996).
   4. K. Kuwahara, S. Nakae, A. Yao, J. Geol. Soc. Japan 97, 1005 (1991).
   2 April 2001; accepted 17 August 2001


   Response: In our study (1), we suggested that an impact event occurred
   at the 250-million-year-old PTB, triggering the most severe mass
   extinction in the history of life on Earth. By exploiting the unique
   ability of the fullerene molecule to trap noble gases inside of its
   caged structure, we were able to determine whether the origin of the
   fullerenes was extraterrestrial (ET) or terrestrial. We have found
   fullerenes with ET helium associated with extinction events in five
   locations at the 65-million-year-old Cretaceous-Tertiary boundary
   (KTB) and in two locations at the PTB (1, 2). Although it has been
   suggested that the fullerenes isolated from some KTB sediments may
   have been associated with terrestrial causes--specifically, with
   global wildfires triggered by the impact event--it has now been
   accepted that the KTB fullerenes are extraterrestrial, delivered
   exogenously to the Earth during the impact itself (3, 4).

   Farley and Mukhopadhyay, at Caltech, report that they have measured
   background levels of 3He across the PTB in sections in Meishan and
   Shangsi, China, and have concluded that there is no evidence for the
   delivery of ET material to the Earth by a bolide. Rather, their
   results are consistent with helium present in a 250-million-year-old
   ash layer found at both boundary sections. We observed significant
   differences between the procedures we used and those carried out
   during their study, however, and we believe that these differences
   influenced the outcome of their experiments.

   In our study, we obtained a ~75-g sample of Bed 25 from S. Bowring
   that contained the base of this unit, which represents the time
   interval during which more than 90% of all marine organisms, most of
   the terrestrial vertebrates, and many plants were brought to an abrupt
   extinction (1, 5, 6). Because we were interested in focusing on this
   discrete event rather than looking at the continuous flux of 3He
   throughout Bed 25, we separated out the carbon-rich basal material,
   characterized by an interstratified reddish-gray
   montmorillonite-illite clay layer. This reduced our bulk sample to the
   ~40 g of material that was demineralized using the procedures outlined
   in (1). The acid residue (442 mg) that represented about 1% of the
   original material was extracted with solvents to isolate the fullerene
   component (14 µg). In contrast, the Bed 25 ash, provided to us by the
   Caltech group, contained less than 0.1% (or 6 mg in 7 g of ash)
   acid-resistant residue, and that fraction appeared to be mostly
   resistant silicates such as zircon. Thus, our contention is that the
   Caltech sample contained neither the organic carbon carrier for the
   3He-rich fullerene component nor the carrier (whatever it may be) for
   the bulk 3He or background flux. Our bulk 3He concentrations in two
   aliquots of the PTB sample yielded values of 0.43 and 0.58 pcc/g,
   while several samples above and below the boundary had 3He
   concentrations about 10 times lower ( <=  0.02 to 0.2 pcc/g) (7).

   To further assess the variability in bulk 3He measured for the Meishan
   samples collected at the boundary (Bed 25) and in samples directly
   above and below this interval, we also obtained a separate suite of
   Meishan samples from S. D'Hondt. The samples collected by D'Hondt were
   evaluated for delta 13C and compared to replicate samples measured in
   (5). This material also represented the changes in lithology at the
   base of Bed 25 and in the sediments above and below. These samples had
   even more 4He (3 to 10 µcc/g) than the samples measured in either our
   study (1) or that of Farley and Mukhopadhyay. In our case, the high
   4He concentrations made it impossible to evaluate the 3He
   concentrations because the 3He/4He ratio was at the abundance
   sensitivity limit. Unfortunately, our samples were not available for
   reassessment of the bulk 3He upon submission of the comment by Farley
   and Mukhopadhyay. We have since reproduced our own results with four
   replicate analyses of the boundary layer. The 3He concentrations at
   the Meishan boundary range from 0.15 to 0.5 pcc/g. We will also
   provide our samples to two separate labs for independent measurements
   of the bulk 3He. We are confident that these labs will reproduce our
   results (1) and will further demonstrate the differences in the
   samples provided by S. Bowring to Caltech and us.

   The differences in bulk 3He and 3He fullerene concentrations appear to
   be directly attributable to sample selection and preparation. By
   homogenizing a 150-g sample of volcanic ash, Farley and Mukhopadhyay
   may reduce the variability and noise in the 3He signature, an
   important consideration when examining long-term IDP flux signals. We
   concur with their conclusion that the volcanic ash would have been
   deposited very rapidly and would not preserve the extraterrestrial
   signature attributed to IDPs. However, when examining "event markers"
   such as fallout from a bolide impact, the homogenization strategy
   would severely dilute the already weak 3He signal present in the bulk
   ash. Variations in the carbon content and 3He concentrations in the
   Bed 25 samples clearly point to the fact that the two groups examined
   very different samples. The change in lithology at the base of Bed
   25 apparently makes a significant difference in the identification of
   the bolide event marker, and care must be taken to identify and
   quantify the helium carriers present in the boundary.

   In a separate comment, Isozaki suggests that the fullerenes we
   detected in the siliceous claystone at Sasayama did not come from the
   PTB. Instead, using lithostratigraphy, he places the true boundary
   somewhere within the carbonaceous claystone above this interval.
   However, as pointed out both by Kakuwa (8) and in Isozaki's comment,
   the PTB cannot be precisely defined in any of the Japanese sections
   because of poor stratigraphic control. Moreover, neither the siliceous
   claystone nor the carbonaceous claystone have age-diagnostic fossils
   to properly date the boundary at Sasayama or in any of the Japanese
   sections (8), as the comment by Isozaki acknowledges.

   The principal difference underlying our placement of the boundary
   compared with that of Isozaki rests on the mechanism that led to the
   PTB mass extinction. Isozaki favors a model involving overturn of
   CO2-saturated deep anoxic water, coupled with a hypothesized
   "hypercapnia" that apparently lasted some 20 million years (9). As
   pointed out by Gin et al. (5), however, the mass extinction that
   occurred at the PTB was abrupt, lasting only a few 100,000 years. Our
   boundary sample, provided by M. Rampino, was selected based upon
   evidence for an extraterrestrial cause (10, 11). So far, we have only
   found fullerene at the boundary, and not in significant concentrations
   above and below (1, 2). Thus, in the absence of any biostratigraphy
   and poor stratigraphic control (8), we feel that the best
   interpretation for the boundary at Sasayama is in the siliceous
   claystone, where fullerene and other extraterrestrial signatures have
   been identified (1, 10, 11).

   Perhaps the most significant drawback to our investigation of the PTB
   to date is the lack of geographic spread and the inability to
   demonstrate that other extraterrestrial signatures, like those
   reported in some KTB sites (1), are also present in the PTB. New
   results on sediments collected from the Meishan PTB show that Fe-Si-Ni
   grains are concentrated in the top 2 cm of Bed 24e and in the
   overlying basal portion of Bed 25 (12). These Fe-Si-Ni grains are
   produced at very high temperatures (Fe, 2890oC; Ni, 2863oC; Si,
   2227 oC), and are thus inconsistent with a volcanic origin but
   consistent with impact-metamorphosed grains found in some impact
   craters and in sediments associated with the KTB (12, 13).
   Interestingly, some Fe-rich nuggets have also been reported in the
   siliceous claystone at Sasayama (14). Based on these new results, it
   would appear that an impact event of global proportions remains the
   best explanation for the most severe biotic crisis in the history of
   life on Earth.

                                                             Luann Becker
                                        Department of Geological Sciences
                                             Institute of Crustal Studies
                                University of California at Santa Barbara
                                             Santa Barbara, CA 93106, USA
                                         E-mail: lbecker@crustal.ucsb.edu
                                                         Robert J. Poreda
                                                  Department of Earth and
                                                   Environmental Sciences
                                                  University of Rochester
                                                 Rochester, NY 14627, USA

REFERENCES AND NOTES

   1. L. Becker, R. J. Poreda. A. G. Hunt, T. E. Bunch, M. Rampino,
   Science 291, 1530 (2001).
   2. L. Becker, R. J. Poreda, T. E. Bunch, Proc. Natl. Acad. Sci. U.S.A.
   97, 2979 (2000).
   3. D. Heymann, L. P. F. Chibante, R. R. Brooks, W. S. Wolbach, R. S.
   Smalley, Science 256, 545 (1994).
   4. P. J. F. Harris, R. D. Vis, D. Heymann, Earth Planet. Sci. Lett.
   183, 355 (2000).
   5. Y. G. Gin, et al., Science 289, 432 (2000).
   6. The boundary layer (Bed 25) provided by S. Bowring was from a
   collecting trip in 1996 and is the same material that preserved the
   carbonate isotopic excursion reported in (5). Our sample contained a
   thin layer of carbon-rich material in the basal portion of Bed 25 (15)
   and is consistent with our finding of fullerene (a pure carbon
   molecule). In contrast, the samples provided to Farley and Mukhopadyay
   were from a different collecting trip (1999) and apparently did not
   contain the carbonaceous layer found in samples collected in 1996 (see
   discussion in text).
   7. These values should have been reported as upper-limit
   concentrations in our paper (1), because the VG5400 mass spectrometer
   has an abundance sensitivity of 108 for helium. A significant fraction
   of the 3He signal for nonboundary samples at Meishan is from the
   low-energy tail of the 4He (the MAP 215-50 mass spectrometer used by
   Caltech does not have this limitation).
   8. Y. Kakuwa, Palaeogeogr. Palaeoclimatol. Palaeoecol. 121, 35 (1996).
   9. A. H. Knoll, et al., Science 273, 452 (1996).
   10. S. Miono, et al., Nucl. Instrum. Methods Phys. Res. B109, 612 (1996).
   11. S. Miono et al., Lunar Planet Sci. XXIX (1998) (CD-ROM).
   12. K. Kaiho, et al., Geology 29, 815 (2001).
   13. Y. Miura, et al., Adv. Space Res. 25, 285 (2000).
   14. S, Miono, Y. Nakayama and K. Hanamoto, Nucl. Instrum. Methods
   Phys. Res. B150, 516 (1999).
   15. S. Bowring, D.H. Erwin, personal communication.

   20 July 2001; accepted 12 September 2001

   Volume 293, Number 5539, Issue of 28 Sep 2001, p. 2343.
   Copyright © 2001 by The American Association for the Advancement of
   Science.

===========
(9) ASTEROID TSUNAMI SIMULATION: NEW WAVE SUPERCOMPUTERS CATCH BIG WAVES

>From Space Daily, 5 June 2002
http://www.spacedaily.com/news/earthquake-02a.html

Albuquerque - June 5, 2002
The new wave in computing - super-fast machines churning out
three-dimensional models viewable in high-tech, immersive theaters - may
teach us more about the big waves that sometimes threaten people who live
near the seashore.

Although earthquakes cause most of these giant waves, called tsunamis,
researchers at the National Nuclear Security Administration's Los Alamos
National Laboratory recently completed the largest and most accurate
simulation of tsunamis caused by asteroids. They presented the first data
from that model today to the American Astronomical Society meeting in
Albuquerque,

The scientists aren't working on a sequel to the Hollywood blockbusters Deep
Impact or Armageddon. They reason that since a large percentage of the
world's population lives on islands, bays or coastlines, a better model
could help predict how tsunamis behave, aiding emergency responders.

Most tsunamis often result when earthquakes send huge landslides tumbling
into bays or oceans. Recent studies of a 30-foot-high tsunami that killed
more than 2,100 people on Papua New Guinea in July 1998 showed the cause was
an underwater landslide more than 2,000 miles away. A landslide in Lituya
Bay, Alaska, in July 1958 inundated the shore of Gilbert Inlet nearly a
third of a mile above the high tide line, and its monster wave is the
largest ever documented.

Computer scientists Galen Gisler and Bob Weaver from the Los Alamos'
Thermonuclear Applications Group, and Michael Gittings of Science
Applications International Corp., created simulations of six different
asteroid scenarios, varying the size and composition of a space visitor
hitting a three-mile-deep patch of ocean at a speed of 45,000 miles an hour.
The Big Kahuna in their model was an iron asteroid one kilometer in
diameter; they also looked at half-sized, or 500-meter, and quarter-sized
variants, and at asteroids made of stone, roughly 40 percent less dense than
iron.

"We found that the one-kilometer iron asteroid struck with an impact equal
to about 1.5 trillion tons of TNT, and produced a jet of water more than 12
miles high," Gisler said.

The team's effort builds on the pioneering research of Los Alamos' Chuck
Mader and Dave Crawford of Sandia National Laboratories. More accurate
models of tsunami behavior are now possible, thanks to recent improvements
in high-performance computers and the codes that run on them funded by the
NNSA's Advanced Simulation and Computing program.

"Although this is important science and has potential value in predicting
and planning emergency response, it's an great way to test and improve the
code," Gisler said. "We can do the problem better now by simulating an
entire tsunami event from beginning to end and bringing more computing power
to bear on some of the key variables."

The code, called SAGE for SAIC's Adaptive Grid Eulerian, was developed by
Los Alamos and SAIC. A majority of large simulations come in one of two
flavors: Lagrange, in which a grid or mesh of mathematical points matches
with and follows molecules or other physical variables through space; or
Eulerian, in which the mesh is fixed in space, thereby permitting
researchers to follow fluids as they move from point to point.

SAGE's power lies in its flexibility. Scientists can continuously refine the
mesh and increase the level of detail the code provides about specific
physical elements in the mesh. The new Los Alamos simulation uses realistic
equations to represent the atmosphere, seawater and ocean crust.

To follow a tsunami from the point of splashdown to a city like Honolulu or
Long Beach, Gisler and his colleagues needed to model in great detail the
interactions between air and water and between water and the surface of an
asteroid. Then they followed how the shock waves moved through the ocean and
the seabed below and how water waves propagated through the water.

"We looked in some detail at a couple of the key variables, especially the
heights of tsunamis as a function of their distance from the point of
impact; we modeled the heights of individual waves and studied how densely
spaced they would be at various distances," Gisler explained.

When the enormous simulation was done - more than a million hours of
individual processor time, or three weeks on Los Alamos' Blue Mountain
supercomputer and the ASCI White machine at Lawrence Livermore National
Laboratory - the team found they had some good news and some bad news for
coastal dwellers.

"The waves are nearly double the height predicted in the earlier simulation,
that's the bad news, but they take about 25 percent longer to get to you,
which could help more people get to higher ground if they had some warning,"
Gisler said.

The model predicts that wave velocities for the largest asteroid will be
roughly 380 miles an hour, while the older model calculated their speed at
close to 500 miles an hour. However, the initial tsunami waves are more than
half a mile high, abating to about two-thirds of that height 40 miles in all
directions from the point of impact.

The earlier model of asteroid-caused tsunamis actually was a patchwork of
three different computer codes, Gisler said. The first code simulated the
big splash and formation of the cavity, the second depicted how the water
collapsed to create the tsunami and a final code followed the tsunami wave
through the ocean.

"With the SAGE code, we were able to avoid a series of potential mistakes
that happen when the model doesn't understand the conditions that you're
passing on from each separate code," Gisler said.

In addition to learning more about how wave height and density vary with
distance from the asteroid impact, the Los Alamos team also improved the way
the computer model represents the strength of materials, which can be
applied to other codes with industrial, defense and scientific applications.

As the asteroid strikes the water, its overall density decreases rapidly.
One challenge for the team was to model accurately how acoustic waves
propagate through the asteroid as it vaporizes. Initially, that problem
appeared insurmountable because both the earlier codes and SAGE showed the
acoustic waves -moving at physically impossible speeds through the highly
mixed materials. By adjusting how the cells in the mesh represent those
rapidly changing materials, the team was able to model the acoustic waves
accurately.

Gisler said the team produced both two-dimensional and three-dimensional
versions of the SAGE tsunami code. The 3-D code required more than 200
million separate cells and ran for three weeks on one-eighth of ASCI White.
Clever code writing and the enormous computational power in the 3.1 teraOPS
Blue Mountain and 12.1 teraOPS ASCI White weren't the only crucial factors
in building the model.

"It's not all about better and better resolution," Gisler said. "You must
have good visualization techniques, such as the three-dimensional power
walls we use at Los Alamos, if you're going to make sense of the data from
these huge calculations."

The modeling continues. Gisler, Weaver and Gittings next plan to study in
three dimensions how an asteroid-induced tsunami will behave if the space
rock strikes a glancing blow, 30 degrees from the horizontal, instead of the
45- and 90-degree angles they've already calculated.

Los Alamos National Laboratory is operated by the University of California
for the National Nuclear Security Administration of the Department of Energy
and works in partnership with NNSA's Sandia and Lawrence Livermore national
laboratories to support NNSA in its mission.

Los Alamos enhances global security by ensuring the safety and reliability
of the U.S. nuclear weapons stockpile, developing technical solutions to
reduce the threat of weapons of mass destruction and solving problems
related to energy, environment, infrastructure, health and national security
concerns.

Copyright 2002, Space Daily

==============
(10) THE INSPIRATION OF ASTRONOMICAL PHENOMENA -- FOURTH CONFERENCE

>From Rolf Sinclair <rolf@SANTAFE.EDU>

THE INSPIRATION OF ASTRONOMICAL PHENOMENA -- FOURTH CONFERENCE
Magdalen College, Oxford (UK) August 3-9, 2003

SECOND ANNOUNCEMENT AND CALL FOR ABSTRACTS/PAPERS

This is the second announcement for the Fourth International Conference on
The Inspiration of Astronomical Phenomena ("INSAP IV") which is now
confirmed to take place in Oxford, England, 3-9 August 2003.

As at previous meetings (Castel Gandolfo, 1994; Malta, 1999; Palermo, 2001),
the conference will explore humanity's fascination with astronomical
phenomena as strong and often dominant elements in life and culture. The
conference will provide a meeting place for artists and scholars from a
variety of disciplines (including Archaeology and Anthropology, Art and Art
History, Classics, History and Prehistory, the Physical and Social Sciences,
Mythology and Folklore, Philosophy, and Religion) to present and discuss
their studies on the influences of astronomical phenomena and address topics
of common interest.

The fourth meeting will be held at Magdalen College, Oxford (UK), starting
Sunday 3 August, 2003. There will be a wide range of guest and keynote
speakers, with confirmed speakers so far including:

Professor Ronald Hutton, University of Bristol
Professor John North, University of Oxford

Opportunities will be provided for 30 minute presentations as well as poster
presentations and the new application form is now linked within the
"application process" section in the INSAP IV webpage:
http://ethel.as.arizona.edu/~white/insap/i4applyx.htm

During the meeting there will be receptions at the Ashmolean Museum, the
Christ Church Picture Gallery, and the Museum of History of Science. The
traditional banquet will be held at the Magdalen College dining hall. A trip
is being planned to Stonehenge and Avebury.

Applications to attend and abstracts must be submitted by 1 December 2002 to

Professor Ray White (rwhite@as.Arizona.edu)
Mr Nick Campion (ncampion@caol.demon.co.uk)

Details of abstracts and proceedings of previous meetings are described on
the website relating to each INSAP Conference, and will give an idea of the
range of subjects presented at these meetings. A similar publication is
planned for the fourth meeting. Further information on INSAP IV and on the
earlier conferences, can be found on the following websites:

http://ethel.as.arizona.edu/~white/insap (general information)
http://ethel.as.arizona.edu/~white/insap/insap4x.htm (for INSAPIV)
http://ethel.as.arizona.edu/~white/insap/insap3.htm
and
http://www.astropa.unipa.it/INSAPIII/index.html (for INSAPIII)

Attendance will be by invitation from among those applying. All
presentations and discussions will be in English. This Conference is
sponsored by the Vatican Observatory and the Steward Observatory

For further information, contact the above or members of the International
Executive or Local Organising Committees (contact details and email
addresses as provided on the INSAPIV website).

June 3, 2002
Please circulate or post this announcement.

================
(11) CRATERS?

>From Giesinger Norbert  <norbert.giesinger@siemens.com>

Dear Dr. Peiser,

looking on a  NASA Satellite picture of the Balcan, I immediately saw some
(vegetation enhanced) markings resembling parts of craters.

See the attaches. In the second, a big circular structure and a small one in
the right lower corner. The pic  is from
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=9270


Text:
The Transylvanian Basin in Romania stands out in brilliant green in this
image from the Moderate-resolution Imaging Spectroradiometer (MODIS) on May
3, 2002. Near the top of the image, the hilly, forested basin is tucked in
between the Carpathian Mountains, running northwest-southeast, and the
Transylvanian Alps, running west-east. To the right of the image is the
Black Sea. The large patch of turquoise water in the Black Sea
</Newsroom/NewImages/Images/images.php3?img_id=9265> is a large
phytoplankton bloom. At the bottom of the image, the Aegean Sea and the Sea
of Marmara is ringed by Greece (left) and Turkey (right).

Greetings from Vienna

Norbert Giesinger

===========
(12) WHY IS MARS SO HARD?

>From James Oberg <joberg@houston.rr.com>

This conference outside of Washington, DC, in September will have a panel on
'Why Is Mars So Hard?', with a gaggle of NASA officials, and me. Look
forward to illumination from struck sparks!
http://klabs.org/richcontent/MAPLDCon02/panel/panel.htm


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