PLEASE NOTE:
*
CCNet 51/2003 - 13 June 2003
-----------------------------
"About 380 million years ago, a rock from space smashed into
the Earth,
say geologists. They believe that the impact wiped out a large
fraction
of life. The idea could strengthen the controversial connection
between
mass extinctions and impacts. Up to now, the only candidate for a
link is
the meteor 65 million years ago that some believe helped
exterminate the
dinosaurs."
--John Whitefield, Nature Science Update, 13 June 2003
"What is unique about Ellwood's work, however, is the means
he uses to
identify the different layers in the geologic record: induced
magnetism.
"Everything is magnetic," he said. "If I put your
finger in a magnetic
coil and turn it on, your finger will be magnetized."
Ellwood uses this
phenomenon to take "magnetic signatures" of geologic
samples. The
magnetic signature of a layer of earth will be the same anywhere
in the
world, making it relatively easy to identify strata, if they can
be
found. These signatures also make it easy to identify meteor
strikes. "The magnetic pattern associated with an impact
layer is often
distinctive, making it easier to find in a thick sequence of
strata," he
said."
--Lousiana State University, 11 June 2003
(1) SECOND MASS EXTINCTION LINKED TO COSMIC IMPACT
(2) EVIDENCE FOR COSMIC IMPACT IN EARLY MASS EXTINCTION FOUND
(3) METEOR IMPACT LINKED TO AN EXTINCTION OF FISH
(4) WORRYING ABOUT THE NEXT BIG SPLASH
(5) HEADLESS COMETS SURVIVE PLUNGE THROUGH SUN'S ATMOSPHERE
(6) BAD NEWS FOR DOOMSDAY COSMOLOGISTS: "UNIVERSE CAN SURF
THE BIG RIP"
(7) RE: SIBERIAN IMPACT FLATTENS 40 SQ MILES OF FOREST
(8) IF IT HIT BOISE THERE WOULD NO LONGER BE A CAPITOL IN IDAHO
(9) PROTECTING AUSTRALIA'S FUTURE
(10) WHAT WOULD HAPPEN IF A MASSIVE OORT CLOUD COMET STRIKES
EARTH?
(11) AND FINALLY: VOLCANOES, ASTEROIDS, BOMBS, BLACK HOLES ...
=============
(1) SECOND MASS EXTINCTION LINKED TO COSMIC IMPACT
Nature Science Update, 13 June 2003
http://www.nature.com/nsu/030609/030609-12.html
Rock from space might have hit life hard 380 million years ago.
13 June 2003
JOHN WHITFIELD
About 380 million years ago, a rock from space smashed into the
Earth,
say geologists. They believe that the impact wiped out a large
fraction
of life.
The idea could strengthen the controversial connection between
mass
extinctions and impacts. Up to now, the only candidate for a link
is the
meteor 65 million years ago that some believe helped exterminate
the
dinosaurs.
Signs of an earlier catastrophe coincide with a disappearance of
many
animals, says Brooks Ellwood of Louisiana State University, Baton
Rouge:
"It doesn't mean that the impact killed off the critters,
but it's
suggestive that it had something to do with it." It's not
known where a
rock struck, although it's possible that traces of a crater might
be
found, he adds.
Other researchers agree that there was an impact around that
time, but
feel the evidence for a mass extinction is much weaker.
Rocks in Morocco laid down about 380 million years ago bear a
layer of
sediment that looks like the debris from a cataclysmic explosion,
Ellwood's team found. The sediment has unusual magnetic
properties, and
contains grains of quartz that seem to have experienced extreme
stresses.
Around this time, about 40% of marine animal groups vanish from
the
fossil record, say Ellwood's team. Ellwood posits an asteroid
slightly
smaller than the 10-kilometre rock suspected of killing the
dinosaurs.
The evidence for an impact is compelling, says geologist Paul
Wignall of
Leeds University, UK. And linking it to a mass extinction would
be a
major finding. "The potential lethality of impacts would be
greatly
increased," he says.
But it's not clear how much disappeared around the time of the
impact -
the death toll may be far lower than Ellwood's team suggest, says
Wignall. He thinks palaeontologists should search the rocks for a
better
picture of what happened at that time.
Even a figure of 40% is a typical extinction rate for that period
of the
Earth's history, agrees palaeontologist Norman MacLeod, who
studies mass
extinctions at the Natural History Museum, London. "It's not
a mass
extinction, it's part of a much longer-term pattern," he
says.
MacLeod doubts that mass extinctions are the result of
extraterrestrial
intervention. "Impacts are quite a common phenomenon,"
he says. "But
they don't correlate significantly with peaks in
extinction."
References
Name, A.B. Impact ejecta layer from the mid-Devonian: possible
connection to global mass extinctions. Science, 300, 1734 - 1737,
(2003).
Copyright 2003, Nature
==============
(2) EVIDENCE FOR COSMIC IMPACT IN EARLY MASS EXTINCTION FOUND
Lousiana State University, 11 June 2003
http://appl003.lsu.edu/unv002.nsf/9faf000d8eb58d4986256abe00720a51/fe4ed1a5901f7ba086256d42006edcaf?OpenDocument
Evidence for meteor in early mass extinction found
Lousiana State University Press Release
Ronald Brown, LSU Media Relations
225-578-3867
June 11, 2003
It's the stuff of science fiction movies. Bruce Willis, by a
mighty
effort, saving the world from extinction by a huge meteor.
But Bruce Willis won't do it, and in our current state of
readiness,
neither will anyone else (sic!). That is why LSU geophysicist
Brooks
Ellwood is plumbing the geologic record, trying to correlate
known mass
extinctions to meteor strikes.
"When we think about the human race and life in general,
what do we
worry about? We worry about nuclear holocaust and major
glaciation. Then
we worry about the giant chunks of rock that fly past Earth all
the
time," Ellwood said.
"We can't see them till they're here (sic!), we can't stop
one (sic!),
so the question is, how often do they hit the Earth and cause
major mass
extinctions? Are extinctions often caused by impacts? If so, we
want to
be sure we are prepared."
Ellwood and four other researchers have just published an article
in the
journal Science in which they tie an early mass extinction to a
meteor
strike. This extinction happened 380 million years ago in what is
called
the middle Devonian. It was a time when only small plants,
wingless
insects and spiders inhabited the land and everything else lived
in the
sea. About 40 percent of all species disappeared from the fossil
record
at this time.
The extinction has been known to geologists for a long time but
this is
the first time it has been tied to a meteor strike. This is also
the
oldest known impact that has been tied to a mass extinction.
Ellwood is quick to point out that because the extinction and the
meteor
strike happened at the same time does not prove the impact caused
the
extinction -- but it certainly suggests it.
One of the great difficulties in determining whether an
extinction
happened on a global scale, or was a local event caused by a
volcano or
some other terrestrial force, is identifying the same strata of
rock at
different locations on the globe. Finding a layer of earth in
Colorado,
for example, and finding that same layer in Australia is no
simple task.
"The same layer of earth is exposed to different conditions
in different
parts of the world," Ellwood said. "Weathering,
upheavals, volcanos,
earthquakes and flooding all confuse the geologic record, making
it
incomplete and open to interpretation."
The layers can also be extremely thin, he said, showing a picture
of the
location of his latest research. The layer he was looking at --
near the
top of a barren plateau in the Anti Atlas desert near Rissani in
Morocco
-- was about the thickness of a felt-tipped marker and only
distinguishable from the soil around it by its reddish color.
What is unique about Ellwood's work, however, is the means he
uses to
identify the different layers in the geologic record: induced
magnetism.
"Everything is magnetic," he said. "If I put your
finger in a magnetic
coil and turn it on, your finger will be magnetized."
Ellwood uses this
phenomenon to take "magnetic signatures" of geologic
samples. The
magnetic signature of a layer of earth will be the same anywhere
in the
world, making it relatively easy to identify strata, if they can
be
found. These signatures also make it easy to identify meteor
strikes. "The magnetic pattern associated with an impact
layer is often
distinctive, making it easier to find in a thick sequence of
strata," he
said.
Working with LSU graduate students Steve Benoist and Chris
Wheeler;
structural geologist Ahmed El Hassani of the University of Rabat,
Morocco; and Devonian biostratigrapher Rex Crick of the
University of
Texas at Arlington, Ellwood was able to find high concentrations
of
shocked quartz, microscopic spherules and microcrysts in this
layer,
sure signs of a meteor impact. Benoist is a paleontologist and
Wheeler
is an isotope geochemist; both have since moved on.
The past 550 million years are divided up by geologists into
about 90
"stages." Each stage is distinguished from another by a
change in the
fossil record. To date, only four of these stages show strong
evidence
of a meteor strike, Ellwood's discovery being the latest, as well
as the
oldest. The most recent, best known extinction is the K-T
boundary at
which the dinosaurs died out, about 65 million years ago. There
have
been five major mass extinctions and many smaller ones since
then.
"We know that meteors have struck the Earth hundreds of
times," Ellwood
said. "If I had to guess, I would say that once every 5
million years a
meteor big enough to cause a mass extinction hits the Earth.
"We could protect ourselves if we wanted. We went to the
moon, we can
figure out how to destroy or deflect a meteor. All it takes is
the
political will -- and an awareness of the threat."
The work of Ellwood and his team, published in the prestigious
journal
Science, is a step in that direction.
=============
(3) METEOR IMPACT LINKED TO AN EXTINCTION OF FISH
The New York Times, 13 June 2003
http://www.nytimes.com/2003/06/13/science/13METE.html
By KENNETH CHANG
Just as dinosaurs died out 65 million years ago when a meteor
struck the
earth, many fish and other creatures of an earlier era - about
380
million years ago - may have been similarly killed off.
Writing in today's issue of the journal Science, geologists at
Louisiana
State University, the University of Texas at Arlington and the
Scientific Institute in Morocco report several lines of evidence
that
point to a meteor impact that coincides with a mass extinction.
Most life was still contained in the oceans then, in the middle
of the
Devonian geological period that is often called the "age of
fishes." The
extinction, while global in scale, was less severe than the
half-dozen
major extinctions in the earth's history.
Still, "It was probably a fairly significant impact,"
said Dr. Brooks B.
Ellwood, chairman of the geology and geophysics department at
Louisiana
State and the lead author of the Science paper.
The research adds a new point of contention to the debate about
the
influence of cataclysms from outer space on the shape of life on
earth.
Dr. Rex E. Crick, a professor of geology at the University of
Texas at
Arlington and another author of the Science paper, said that
small
extinctions caused by numerous small meteor impacts "could
be one
mechanism for driving evolution."
That is still far from clear. The end of the dinosaurs is the
only one
that geologists universally agree coincides with a meteor impact.
Even
there, some scientists believe that vast volcanic eruptions in
India
contributed more to the extinctions.
Scientists have also reported tantalizing clues of meteor impacts
coinciding with major extinctions.
In 2001, Dr. Luann Becker, then a visiting professor at the
University
of Washington, reported finding extraterrestrial gases in the
geologic
layer deposited 250 million years ago. That coincides with the
largest
mass extinction in the planet's history, when it is believed that
90
percent of marine species and 70 percent of backboned land
animals died.
That finding, though, has not been reproduced and is widely
discounted
by experts in the field.
Last year, Dr. Paul E. Olsen, a professor of earth and
environmental
sciences at Columbia University's Lamont-Doherty Earth
Observatory in
Palisades, N.Y., reported some signs of a meteor impact at 200
million
years ago, the time of another mass extinction. Dr. Olsen's
evidence
included a modest spike in levels of iridium, an element more
common in
meteors than on earth.
But scientists also know of several instances - like the
formation of
the Manicougan crater in Quebec 214 million years ago - when
meteors
slammed into the planet but had little if any effect on plant and
animal
life.
In the new research, Dr. Ellwood and his colleagues examined
samples of
rocks from Morocco. In the layer of rock 380 million years old,
corresponding to the extinction, they found grains of quartz with
microscopic lines that form when it is hit with a tremendous
impact.
They also discovered spheres and crystals less than one-hundredth
of an
inch wide that may be droplets of rock that melted when a meteor
struck.
As further evidence, they identified elevated levels of elements
like
nickel, chromium and cobalt, all associated with meteors.
The scientists did not find these indicators in rocks several
yards
above or below the extinction layer. They also reported chemical
signs
in carbon in the rocks that indicate rapid, widespread deaths of
organisms. "All of those things together are very strong
evidence that
this is an impact layer," Dr. Ellwood said.
It is not known where the meteor hit or how large it was.
Dr. Olsen, who was not involved with the report from Morocco,
said the
new evidence was more convincing than what he had presented for
the
later extinction. "On a scale of 0 to 100, I would put it at
50 and
probably put my own at a 30," he said.
Dr. Ellwood said the researchers also found signs of a large
iridium
spike, but because of uncertainties about the testing method,
they did
not report that in the Science paper.
Dr. Ellwood also said that the researchers had found shocked
quartz of
the same age in Spain, but that evidence has not been published.
"I'm
pretty sure we're going to find it elsewhere," he said.
Copyright 2003, The New York Times
==============
(4) WORRYING ABOUT THE NEXT BIG SPLASH
Casa Grande Dispatch, 11 June 2003
http://www.zwire.com/site/news.cfm?newsid=8285093&BRD=1817&PAG=461&dept_id=68561&rfi=6
Alan Levine
The headline read: "Massive tsunami sweeps Atlantic Coast in
asteroid
impact...." It was at that point that I wished that I had
taken a
speed-reading course, because the rest of the headline read:
"...scenario for March 16, 2880."
I'm really thankful for all those folks who spend countless hours
each
week with their eyeballs glued to the small end of a telescope as
they
search the skies, keeping constant vigil for anything heading
toward
Earth that's larger than a frozen turkey. The men and women of
NASA and
the Jet Propulsion Lab, college professors and their student
assistants
and even the amateur astronomers are doing a commendable job of
standing
guard at Earth's edge, ready to climb the clock tower and ring
the bell
at the first sign of an outer space object that's threatening our
world.
But that's only reassuring to a degree, because one must wonder:
If some
of the rocks spinning around in the asteroid belt should engage
in a
game of billiards next week and end up knocking an eight-ball
earthward
and the target was downtown Phoenix, would our celestial sentries
have
enough of an advance notice to dial up a few 602 numbers and
advise
Phoenicians to get out of town?
My question arises out of an incident that took place on March 8,
2002,
when an asteroid the size of a Boeing 747 passenger jet slipped
past all
of the sky watchers, flew within 280,000 miles of planet Earth -
just
beyond where the moon hangs out - and was finally discovered a
day
later. Of even greater concern is the fact that three more days
passed
before the rest of the world was notified of the event.
With that amount of miles between Earth and asteroid 2002 EM7,
most
people would not consider that a close call, but in terms of the
vastness of space, it was like getting brushed back by a Randy
Johnson
fastball.
According to Jeff Hecht, a journalist with New Scientist, EM7 was
difficult to see because it was moving outward from the innermost
point
of its orbit approximately 50 million miles from the sun.
"When it passed closest to the Earth," Hecht wrote,
"it was too close to
the sun to be visible. Asteroids approaching from this blind spot
would
not be seen by astronomers. If a previously unknown object passed
through this zone on a collision course with Earth, it would not
be
identified until it was too late for any intervention."
This revelation doesn't exactly have me reaching for a bottle of
tranquilizers and a hard hat. On the other hand, I don't think
that I'll
be resting too comfortably in my recliner chair the next time an
ultra-light aircraft buzzes my house, because despite all of the
sophisticated glass pointing skyward and all of the incredible
technology available to map and track a large variety of outer
space
objects, there is no question that the occasional maverick
asteroid can
slip through the fence and trample the grass in our front yards.
This takes me back to the UCSC press release. Here we have a
group of
scientists tracking an asteroid that measures nearly a mile in
diameter,
known as 1950 DA, to such a fine degree that they are able to
predict an
intercept course with Earth some 876 years from now and have even
managed to pinpoint the area of impact - the Atlantic Ocean,
about 350
miles from Cape Hatteras, N.C.
Since the big rock will hit the water at 38,000-miles-per-hour,
it will
have the same effect as a 60,000 megaton bomb. The asteroid will
vaporize on impact, creating a cavity approximately 12 miles in
diameter
and reaching all the way down to the seafloor, which is about 3
miles
deep at that point.
The computer-driven scenario shows that instead of creating one
big
tidal wave, the water rushing back in to fill the cavity results
in a
kind of ripple effect, a series of shock waves of varying
frequencies
and wavelengths that start out at about 16 feet in height and
eventually
reach tsunami dimensions of from 200 to more than 400 feet. At
the end
of one hour, 400-foot waves will have swept across the coasts of
Virginia and the Carolinas, and within another hour, the entire
East
Coast will be deluged under 200-foot waves. Eight hours later,
European
coastal cities will be looking at a wall of water somewhere
between 30
and 50 feet high.
The planetary scientists at UCSC are telling us that the
probability of
impact from 1950 DA is only about 0.03 percent, but they're also
issuing
cautions that yet-to-be-detected space rocks pose just as much of
a
threat. The supposed good news is that a NASA-led campaign to
locate
large asteroids in near-Earth orbits is about half way towards
its goal
of detecting 90 percent of those larger than a half-mile in
diameter.
"Until we detect all the big ones and can predict their
orbits," said
Eric Asphaug, an associate professor of earth sciences, "we
could be
struck without warning. With the ongoing search campaigns, we'll
probably be able to sound the "all clear" by 2030 for
90 percent of the
impacts that could trigger a global catastrophe."
I don't know about anyone else, but I'm not particularly
comforted by
this information, for even when we reach 90 percent efficiency 27
years
from now, what about the other 10 percent? What's really scary
about all
this is the fact that asteroid 1950 DA was discovered in 1950,
studied
for 17 days and then was lost for 50 years. It was rediscovered
on New
Year's Eve 2001. I wonder how many more sneaky asteroids there
are out
there?
©Casa Grande Valley Newspaper 2003
==============
(5) HEADLESS COMETS SURVIVE PLUNGE THROUGH SUN'S ATMOSPHERE
Paal Brekke <pbrekke@esa.nascom.nasa.gov>
Bill Steigerwald June 10, 2003
NASA Goddard Space Flight Center
(301) 286-5017
Release 03-65
HEADLESS COMETS SURVIVE PLUNGE THROUGH SUN'S ATMOSPHERE
A run through the jungle is too easy; for the ultimate reality
show
contest, try a race through the Sun's atmosphere, where two
comets
recently lost their heads. The tails from a pair of comets
survived a
close encounter with the Sun, even after the Sun's intense heat
and
radiation vaporized their heads (nuclei and coma), an extremely
rare
event photographed by the Solar and Heliospheric Observatory
(SOHO)
spacecraft.
On May 24, 2003, a pair of comets arced in tandem towards the
Sun,
their paths taking them to just 0.1 solar radii above the Sun's
surface, deep within the searing multimillion-degree solar
atmosphere
(corona).
They belong to the Kreutz family of sun-grazing comets, often
seen by
the SOHO spacecraft while diving towards their final rendezvous
with
the Sun. But as in humans, twins are rare. Even more so, this
pair
showed another very unusual trait: What looks like a faint tail
(or
"puff of smoke") can be seen moving away from the Sun,
seemingly
emanating from a point in the orbit beyond the comet's closest
approach. Normally, sungrazers simply fade and disappear at an
earlier stage, obliterated by the Sun's intense heat and
radiation
pressure.
Another pair of Kreutz sungrazers with such a "headless
tail" was
observed in June 1998, when the observing geometry was very
similar.
But out of more than 600 sungrazing comets observed during more
than
six years by SOHO, this is only the third showing any signs of
such
behavior. However, this seems now likely to confirm the existence
of
such comets.
"Everyone who's seen this agrees it's a very interesting
observation," said Dr. Douglas Biesecker, a solar researcher
at the
National Oceanic and Atmospheric Administration's Space
Environment
Center in Boulder, Colorado, and the head of SOHO's comet
discovery
program. SOHO has become the most prolific comet finder in
history.
The tail is most likely the dusty remains of the comet's nucleus,
being pushed out by sunlight (radiation pressure) after all the
ice
in the nucleus has evaporated, thus eliminating the processes
maintaining a bright coma surrounding the nucleus. Studies of the
dust cloud may reveal clues to the size distribution of the dust
grains.
"The fact that the tail 'holds together' so well probably
means that
the dust is mostly the same size," said Biesecker.
Comets are chunks of ice and dust that zoom around the solar
system
in elongated orbits. This "dirty snowball" is the
nucleus of the
comet; it ranges in size from a large boulder to a large city. As
the
comet gets close to the Sun, solar heat and light liberate gas
and
dust from the nucleus, forming the coma, which is an extensive,
bright cloud around the nucleus, and one or more tails. A comet's
dust tail can be millions of miles (kilometers) long and is
pushed
away from the Sun by sunlight. Comets also have a tail of
electrically charged particles (ions) that is usually fainter and
is
pushed away from the Sun by the solar wind, a thin stream of
electrified gas that blows constantly from the Sun. Both tails
point
away from the Sun, even for comets that are traveling back
outwards
in the solar system. Studies of the tails can reveal changes in
solar
wind structure and radiance of the Sun.
SOHO is a project of international cooperation between the
European
Space Agency and NASA. For images and movies of this event, refer
to:
http://soho.nascom.nasa.gov/pickoftheweek/old/27may2003/
==============
(6) BAD NEWS FOR DOOMSDAY COSMOLOGISTS: "UNIVERSE CAN SURF
THE BIG RIP"
Nature Science Update, 11 June 2003
http://www.nature.com/nsu/030609/030609-7.html
Alternative proposed to dark energy's cosmic doomsday.
11 June 2003
PHILIP BALL
The end of the world is not so nigh. A Spanish scientist has
found a
loophole in the suggestion that there might be a Big Rip in the
universe
about 22 billion years from now1.
Earlier this year, US researchers showed how the recent discovery
of an
accelerating universe raises the possibility that in future
everything
may rend asunder, starting with clusters of galaxies and ending
with the
smallest of subatomic particles2.
Now Pedro González-Díaz of the Consejo Superior de
Investigaciones
Científicas in Madrid is arguing that, even if the universe is
built the
way Big Rip proponents suggest, a cosmic doomsday is not
inevitable. The
universe might just go on expanding, he says.
Given the timescales involved, we needn't start fretting too much
either
way. But there's no denying how terrible the Big Rip sounds. It
is a
kind of breakdown of all the fundamental forces of nature, as
empty
space becomes so full of energy that it overwhelms them. When
that
happens, everything falls apart.
Phantom menace
The destruction begins, say Robert Caldwell of Dartmouth College
in New
Hampshire, USA, and his coworkers2, about a billion years before
it
ultimately ends in a Big Rip. First, gravity loses its grip at
cosmic
scales, allowing clusters of galaxies to drift apart.
Sixty million years before doomsday, our own galaxy, the Milky
Way,
fractures as stars slip from each other's grasp. A few months
before the
end, planetary systems like the solar system will be dismembered,
and 30
minutes before the Big Rip, the planets and stars themselves
disintegrate.
In the split-second before the end, atoms and molecules are torn
apart,
then the particles that constitute them. Finally, space itself
flies
open.
All of this is driven, the argument goes, by something known as
phantom
energy, which fills all of space. The density of phantom energy
increases with time, like a bomb that grows ever bigger.
Energy bar
No one knows if phantom energy exists at all. But recent
astronomical
observations hint that it might.
Five years ago, astronomers found that the universe is expanding
at an
ever-accelerating rate. The cosmic speed-up suggests that space
is
permeated by dark energy, creating a kind of pressure that
opposes the
pull of gravity.
One explanation for this dark energy reinstates the idea of a
cosmological constant, which Albert Einstein first proposed and
then
rejected in the early twentieth century. According to this
hypothesis,
the universe will merely expand forever, with distant galaxies
gradually
winking out of sight.
An alternative possibility is that the dark energy takes the form
of
so-called phantom energy. This is more pathological than the dark
energy
supplied by a cosmological constant, Caldwell and colleagues say.
They
point out that phantom energy will become ever more dominant over
other
kinds of matter and energy as time progresses.
In the split-second before the end, atoms and molecules are torn
apart,
and then the particles that constitute them
Or perhaps not. González-Díaz points out that some kinds of
phantom
energy can be well behaved, avoiding the blow-ups and
instabilities that
lead to a Big Rip.
Dark energy can be thought of as a kind of gas filling all of
space, the
density of which is proportional to its pressure. González-Díaz
shows
that if one assumes that this 'gas' has certain properties -
specifically, that the speed an oscillation passes through it
decreases
with time - then there is no longer a Big Rip. This might sound
contrived, but actually, González-Díaz reckons it is a more
realistic
kind of behaviour than the alternatives.
To settle the debate over what's in store for the Universe,
astronomers
will have to probe deeper into how it looked soon after the Big
Bang,
and how it is expanding now. Questions like this are being
investigated
by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite
operated by
NASA.
References
González-Díaz, P. F.You need not be afraid of phantom energy.
Preprint,
http://xxx.arxiv.org/abs/astro-ph/0305559,
(2003). |Article|
Caldwell, R. R., Kamionkowski, M. & Weinberg, N. N. Phantom
energy and
cosmic doomsday. Preprint, http://xxx.arxiv.org/abs/astro-ph/0302506,
(2003). |Article|
© Nature News Service / Macmillan Magazines Ltd 2003
========LETTERS TO THE MODERATOR =============
(7) RE: SIBERIAN IMPACT FLATTENS 40 SQ MILES OF FOREST
David Dunham <dunham@erols.com]>
Has anyone obtained 1-m resolution images of the site yet, with
Ikonos,
Spot, or one of the other commercial high-resolution imaging
satellites?
Did anyone do that shortly after the event? Since the flash was
seen by
the Air Force monitoring satellites, the location should have
been known
right away - I think I remember coordinates being given in some
of the
early reports.
David
===============
(8) IF IT HIT BOISE THERE WOULD NO LONGER BE A CAPITOL IN IDAHO
Worth F. Crouch <choctaw@jps.net>
Recent articles about the Japanese Muses-C space probe attempting
to
help scientists understand more about asteroids, and their little
meteorite cousins, delivered some bad news. Even though there are
periodic
collisions between asteroids and the Earth, two North American
fireball
networks were disbanded probably because politicians see little
need in
trying to predict cosmic collisions and protect the Earth.
However, the scientific community has overwhelmingly decided that
asteroid, comet, and meteorite impacts can damage Earth's
civilizations.
Nevertheless, there has been a heated debate over how often
deadly
cosmic collisions occur. The standard opinion is that we have
nothing to
fear, because the Earth is only struck by catastrophic impacts at
best
every 100,000 years. On the other hand, for years I have argued
in
various scientific publications, papers, and letters, that we
currently
have no way of predicting collisions or even determining their
frequencies due to insufficient data, protuberance, and
mathematical
chaos.
In 2001, I sent a letter to Professor Simonenko, the head of
Russia's
atomic energy program, and wrote, "... it has not yet been
determined
how many Near Earth Asteroids (NEA) there are or how many could
significantly damage the Earth. Short period comet paths are not
exactly
known and the long period comets emerging from the Oort cloud are
relatively unknown and they can surprise the Earth at any time.
Therefore, randomness in space, it is currently a deficiency of
our
knowledge. It then seems just a matter of time, and imperfect
predictability before the Earth will be impacted by an asteroid
or comet
capable of catastrophic devastation or at least great regional
damage."
Now it seems that last year, 9/25/02, a meteorite fireball fell
in
Russia near the Vitim River between the towns of Bodaibo and
Balakhninsky. According to Interfax, the collision caused strong
earthquake like tremors, and flashes of light in the night's sky.
The
crash site of the meteorite currently has been determined to be
in the
Irkutsk region.
On Friday Alexander Bogun, deputy head of the Irkutsk district
administration, reported that an expedition from the Kosmopoisk
scientific organization found burnt trees covering an area of
about 60
square miles, and pieces of the meteorite were found 30 miles
from the
village of Mama. Without a doubt, this was the second largest
meteorite
to fall in Russian, since the famous 1908 Tunguska meteorite.
The RIA NOVOSTI correspondent Edward Puzyrev wrote that the
precise
coordinates have been only now fixed, because deep snow hindered
work,
and now scientists can get down to a more detailed study of the
meteorite.
Robin Shepard of the Times reported that fragments of the
meteorite had
apparently exploded into shrapnel 18 miles above the Earth with
the
force of at least 200 tones of TNT. Moreover, "If it had hit
Central
London, Britain would no longer have a capital city."
Furthermore, the little asteroid or meteorite, that wasn't
expected,
could have obliterated New Your City, Tokyo, Boise, Los Angelis,
or
depending on where the meteorite crashed a tsunami could have
been
generated wiping out coastal cities. In addition, without a
warning or
defense we face another collision at any time, because
politicians and
even some scientists do not yet understand that randomness in
space is
still not fully understood.
CONTACT:
Worth F. Crouch (Talako)
4875 Cedar Ridge Dr.
Auburn, CA 95602
(530) 269-3152 or (530) 906-5106
choctwa@jps.net
============
(9) PROTECTING AUSTRALIA'S FUTURE
Michael Paine <mpaine@tpg.com.au>
Dear Benny
Is there a chance of the Australian government changing its
policy on
Spaceguard? To my surprise the new slogan of the ruling Liberal
Party
is:
PROTECTING
SECURING
BUILDING
Australia's future
(their order and emphasis)
Wow!
yours skeptically
Michael Paine
=============
(10) WHAT WOULD HAPPEN IF A MASSIVE OORT CLOUD COMET STRIKES
EARTH?
James Marusek <tunga@custom.net>
Dear Benny
Long period comets originate in the Oort Cloud, a huge sphere
comprising
trillions of comets that surrounds the solar system, 20,000 to
100,000
Astronomical Units (AU) from the Sun. Long period comets will
often
return after thousands or even millions of years, or not at all.
The
Oort Cloud is estimated to contain 7,000,000,000,000 comets.
There are 5
to 10 long period comets that approach the Sun each year. Some of
these
comets are behemoths, which are several hundred miles across.
What would happen if a massive Oort Cloud comet struck the Earth?
The
impactor would smash through the planet's crust and drive deep
into the
planet's interior where it would release most of its energy. A
large
comet, 200 miles in diameter, traveling at 100,000 mph with a
density of
0.75 gm/cc would have impact kinetic energy equivalent to 3.1 x
1012
megatons of TNT. The kinetic energy from the Cretaceous/Tertiary
(K/T)
impact of 65 millions years ago, that caused the extinction of
many
lifeforms including dinosaurs, is estimated at 108 megatons of
TNT. One
of these large comets would release 31,000 times the energy of
the
impactor that caused the K/T extinction. The shock waves released
inside
the planet would tear Earth's crust apart. A large part of the
1.24 x
1025 Btu of impact energy would be released as thermal energy
superheating Earth's magma.
The destruction of Earth's crust would release flood
vulcanization on a
massive scale. The surface of the Earth would become a molten sea
of
lava. Vulcanization would release vast quantities of compressed
gases
into the atmosphere. Magma contains several dissolved gases.
These gases
consist predominantly of steam (90%), carbon dioxide, sulfur
dioxide,
hydrogen sulfide, hydrogen and fluorine. The impact would produce
a
thick heavy atmosphere. Magma is very hot, with temperatures
ranging
from 1,650 to 2,200° F. Heat release from the magma would
dramatically
expand the atmospheric envelope to many times its original
thickness. An
outer layer of clouds composed of water vapor and sulfur dioxide
would
form around the entire planet. The outer layer would reflect most
of the
solar radiation back into space, leaving the planet in continual
darkness. The inner thick layer of carbon dioxide would act as a
heat
blanket, sealing and trapping the volcanic heat at the surface of
the
planet. Carbon dioxide is very effective at blocking infrared
radiation.
The planet's surface temperature would hover around 2000° F.
After several million years, the planet would cool down and a
crust
would form. The crust creates an insulation barrier between the
hot
magma and the atmosphere. Surface temperatures would drop below
1,000°
F. Clouds composed of sulfuric acid droplets would rain acid down
onto
the planet and over time bleed out into surface mineralization.
Sulfur
dioxide/sulfuric acid clouds would thin substantially. Sunlight,
although dim, would make its way to the planet's surface. The
atmospheric shield inhibiting photosynthesis would dissolve away.
The
intense period of vulcanization on the planet would begin to come
to an
end.
The planet Venus is almost an identical twin with Earth. The two
planets
have approximately the same size, mass, density, volume, bulk
composition, gravity and distance from the Sun. But that's where
the
similarities end. Venus has no oceans. The average temperature at
the
surface of the planet is 865o F. The planet has a very heavy
atmosphere,
which is composed of primarily carbon dioxide (97%). Atmospheric
pressure at the surface of the planet is 92 times that of Earth.
Clouds
of sulfur dioxide float high above the surface of the planet and
rain
down pure sulfuric acid. Because of its cloud cover, Venus is the
brightest planet in the night's sky. It reflects approximately 80
percent of the sunlight incident on the planet.
Venus has more volcanoes than any other planet in the solar
system. Over
1,600 large volcanoes have been identified and there are perhaps
a
million smaller ones. Volcanic intensity on the planet has
slowed. There
are very few impact craters (~ 900) on the surface, indicating
the
planet's crust is still quite young. Scientist estimated the
crust was
resurfaced 300-500 million years ago. The impact craters on Venus
are
quite different than those on the moon and on other planets in
the solar
system. Approximately 30% of the impact craters are partially
embayed
with lava. Lava floods the crater floor and in some cases
breached the
crater's rim and overflows. This observation would be expected if
the
planet's crust were quite thin.
Venus is presently in a stage of development analogous to the end
of the
Hadean Era of the Precambrian Eon on Earth. At this stage the
earliest
forms of life appeared. These hardy forms thrived in the
superheated,
very toxic environment. They fed off the sulfur and the carbon
dioxide
and transformed the planetary environment into a viable modern
environment of moderate temperatures, oxygen and water.
Venus is different from Earth in other ways. Venus has only minor
axis
rotation. The planet makes one complete spin approximately every
243
days. Venus has an extremely weak magnetosphere. The magnetic
field of
Venus is 100,000 times weaker than Earth's field. The
magnetosphere
provides the planet protection from solar winds, plasma of hot
ionized
gas that flows out from the sun, and from cosmic radiation. The
lack of
a planetary magnetic field allows charged particles to collide
with its
atmosphere. These collisions strip the outer atmosphere of the
lighter
atoms, hydrogen and helium. Collisions of charged particles would
also
destroy the ozone layer that protects the planet from ultraviolet
radiation. Radiation would split apart water molecules into
hydrogen and
oxygen. The hydrogen would then be blown away into deep space by
the
super-fast hydrodynamic escape process and lost forever. As a
result,
Venus has no oceans and minimal atmospheric water vapor. Water
makes up
only 0.003 percent of the present atmosphere. The water has
essentially
been bled off the planet. The lack of available moisture
represents one
of the key factors making it difficult for life to establish a
foothold
on the planet.
What would happen if a massive Oort Cloud comet were to strike
the
Earth? The answer is Venus. It's not everyday that we have the
opportunity to witness a planet being reborn. In the case of
Venus, the
big question is "Will it be a stillbirth?" Or maybe a
better question is
"Should we help in the delivery?"
James Marusek
==============
(11) AND FINALLY: VOLCANOES, ASTEROIDS, BOMBS, BLACK HOLES ...
Edmond Journal, 11 June 2003
http://www.canada.com/edmonton/edmontonjournal/story.asp?id=2A5F1333-446E-49D1-A5C1-E3279EA50629
Scientist says the world will end by 2020 -- one way or another
Tom Spears
Wednesday, June 11, 2003
OTTAWA - Duck, it's nearly the end of the world, says a renowned
British
scientist who foresees Armageddon, or something like it, is less
than 20
years away.
Sir Martin Rees, the United Kingdom's honorary Astronomer Royal,
has
taken a grim look at all the bad things that science or natural
disasters could do to us. He says there's at least a 50-50 chance
something really, really bad will kill untold millions by the
year 2020.
There isn't much Rees likes when he surveys the world.
He wonders, what if the terrorists who hit the World Trade Center
used
plutonium weapons instead?
If such weapons seem unimaginably big, there are always tiny
little
machines.
Nanotechnology is the art of making machines the size of a single
molecule. Most scientists talk about using it to make useful
things such
as little sensors, or gadgets that will deliver drugs to precise
targets
in our cells.
Rees takes the gloomier view that nanotech machines will
replicate
themselves on an out-of-control scale.
That is, if we aren't hit already by natural disasters such as
volcanoes.
Sure, we've had lots of those in the past, but the veteran
astronomer
hypothesizes about a "super-volcano" so huge that its
smoke blots out
the sun and makes Earth unlivable.
There's one waiting to pop right now under Yellowstone National
Park in
the U.S., he believes.
Speaking of climate, it may become hot enough to evaporate huge
amounts
of fresh water and transform farmland into wasteland.
That is, if we aren't hit first by an asteroid.
One wiped out the dinosaurs 65 million years ago. Are we overdue?
Martin's worried sick about that.
But not as sick as bioterrorism will make us if we genetically
engineer
nasty bugs and they escape and breed and spread before we have a
chance
to build up immunity to them. But even bugs won't stand a chance
from a
black hole.
Scientists who study matter may some day squash matter together
in such
a dense mass that it forms a black hole that grows bigger and
bigger
until it just sucks in all of Earth and anything else in this
part of
space.
Or so goes Rees's apocalyptic theory.
His musings blur an old line between astrologers, who foretell
the
future, and astronomers.
Rees is 60 years old, a theoretical astrophysicist and black hole
expert
at Cambridge University. He has been busy writing a book, just
published, with the cheery title Our Final Hour.
Buy it before 2020.
© Copyright 2003 Edmonton Journal
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