PLEASE NOTE:
*
CCNet, 32/2003 - 20 March 2003
-------------------------------
"Legend has it that when two people get together and er...
bond, the Earth will move - at least in a metaphorical sense.
Likewise, it takes two heavenly bodies, an impactor and a target,
to come together with Earth-shattering force to form a crater.
There's nothing dreamlike about this: it happens, frequently,
throughout the solar system. Impact catastrophes are
routine."
--Graeme Addison, Popular Mechanics, 18 March 2003
"If we were faced with the threat of an asteroid impact, I
expect we could rise to the challenge. There is nothing
inherently 'impossible' in the context of present
technology."
--Alan Harris, Space Science Institute, 18 March 2003
(1) AVERTING KILLER ASTEROIDS
The Boston Globe, 18 March 2003
(2) VERY LARGE METEORITE FELL DOWN IN SIBERIA
Pravda, 18 March 2003
(3) HAVE NO FEAR, A TSUNAMI WILL NOT APPEAR
Astronomy.com, 18 March 2003
(4) HEAVENLY BODIES STIR UP ROUTINE CATASTROPHES
Popular Mechanics, 18 March 2003
(5) AND FINALLY: MEMES OF SUPERSTITION
Tech Central Station, 19 March 2003
===========
(1) AVERTING KILLER ASTEROIDS
>From The Boston Globe, 18 March 2003
http://www.boston.com/dailyglobe2/077/science/Averting_killer_asteroids+.shtml
>From nuking to nudging, researchers plan to save the planet
By Larry O'Hanlon, Globe Correspondent, 3/18/2003
Whether or not an asteroid threatens Earth any time soon, there
are people already thinking up schemes to nudge, nuke, slam,
sling, vaporize or paint -- yes, paint -- the chunks of cosmic
debris off track and save the planet.
Moving huge hunks of rock in space into safer orbits is actually
a sort of specialty among asteroid and comet researchers who are
determined that humanity not go out with a tremendous bang, as
the dinosaurs did 65 million years ago.
We have an advantage the dinos didn't: We can see it coming.
There are at least 10 astronomical surveys around the world
actively hunting down near-Earth asteroids, or NEAs -- those
having orbits that occasionally bring them into the space near
Earth's orbit. Estimates in a February report by the National
Optical Astronomy Observatory put the number of globally
catastrophic NEAs -- those a half-mile or more in diameter -- at
between 900 and 1,230 out of a total population of perhaps a
million NEAs. So far, about 2,225 NEAs have been found ranging
from 30 feet to about 20 miles across.
"We're looking to see if there are any 21st-century hazards
out there," MIT asteroid researcher Richard Binzel
explained. And, if astronomers find any on hazardous courses, he
said, it is more than likely we'll have decades to prepare to
respond to the threat.
Just what our response will be depends a lot on the asteroid. The
one thing that is certain is that we probably will not be able to
destroy one. We just don't have the firepower to pulverize a
cosmic Mount Everest. The widely accepted alternative is to nudge
the asteroid into a slightly new orbit many years before it's a
danger, so that, by the time it reaches Earth's vicinity, it's
way off course and misses. For asteroids of about a half-mile in
diameter -- the lower end of the globally threatening asteroid
scale -- a nuclear nudge might work.
"That solution has its merit," said Joseph Spitale, a
scientist at the University of Arizona's Lunar and Planetary
Laboratory. But there are a lot of downsides, he said. For one
thing, nobody is keen on launching nuclear weapons, and it's not
likely they'd be very accurate or effective. "My current
feeling is that a buried explosion would be needed if one were
going the nuclear route," said Alan Harris, senior scientist
at the Space Science Institute. "That requires a rendezvous
-- just zipping by and `nuking' it on the fly won't do."
As in any approach to nudging asteroids, there is the danger of
knocking one into an even more perilous course. That's why better
tracking data is needed than what telescopes offer, Harris said.
"Ordinary optical tracking with a telescope is adequate to
certify that an asteroid is not even going to come close for the
next century. But if the answer is that it will come close, maybe
even hit, then much more precise tracking is needed.
"If one were to land a radio beacon on the asteroid, then
precision tracking would be about the same as tracking
spacecraft, which is easily accurate enough for the job."
A far-less-spectacular approach for moving NEAs is to have them
move themselves, which can be done by changing their color. It
turns out that the dark surfaces of most asteroids absorb a lot
of solar energy, which is radiated back out into space as heat.
That heat radiation actually produces thrust -- like a very weak
rocket engine -- and influences an asteroid's orbit. The effect
is known as the Yarkovsky effect, and explains the anomalous
orbits of some artificial satellites.
It's been suggested wrapping an asteroid in a thin film, Spitale
said, or perhaps coat or paint it with reflective material to
turn off the Yarkovsky effect. Done early enough, it might be
enough to alter an asteroid's orbit and save the planet.
Unfortunately, the Yarkovsky effect is too weak to move asteroids
larger than a half-mile in diameter unless you have centuries of
time to work with, said Jay Melosh, also of the University of
Arizona's Lunar and Planetary Laboratory. The dinosaur-killing,
6-mile-wide asteroids out there require more punch than even
nuclear bombs or the Yarkovsky effect can pack, Melosh said.
"I have a proposal out to deflect an asteroid by means of a
solar reflector," Melosh said. His plan works a lot like a
kid using a magnifying glass in the sun to roast ants. Melosh
proposes using a lightweight, reflective Mylar-like material
called Kaptan to focus sunlight on a small area on the asteroid
surface. With a large enough Kaptan reflector, it would be
possible, he said, to continuously heat a spot on the surface so
that it shoots out a jet of vaporized rock. That jet would work
like a rocket engine, pushing the asteroid in the opposite
direction.
Melosh said his proposal is often confused with a plan known as
the solar-sail approach. That idea would have astronauts attach a
giant solar sail to a tumbling asteroid to catch the steady
torrent of particles coming from the sun known as the solar wind.
The gigantic sail would turn an asteroid into a very large, odd,
and sluggish interplanetary sailing ship. It's a neat idea,
Melosh said, but just how to rig a constantly tumbling rock with
a sail that can stay aligned to catch the solar wind makes the
idea fiendishly complicated.
Yet another plan is what's called the mass driver. It would
involve building a magnetic rail on an asteroid's surface that
could be continuously loaded with rocks mined from the asteroid
itself. Those rocks would be shot down the rails and flung into
space, Melosh said. All that flinging would gradually push the
asteroid in the opposite direction and change its course. It
would take a lot of work, but it's within the realm of
possibility, he asserted.
About the only idea that has been totally discredited is what
might be called an asteroid tugboat. That's a giant rocket ship
with lots of fuel from heck knows where. The ship would fly to
the asteroid, put its nose to the stone, and push it out of
harm's way. Unfortunately, "it's just plain stupid,"
Melosh said. The size and cost of such a ship would be immense,
and the amount of fuel that would be needed to propel a mountain
in space is just staggering. "You'd be better off," he
said, "running the rocket into the asteroid," and
transferring the momentum of the ship to the asteroid.
Melosh argued that his solar reflector asteroid deflector avoids
a lot of complications because it doesn't even require landing on
the asteroid, or fuel to power it. What it does entail, however,
is a massive manned space program to build the ships and
technology to fly to the asteroid, build the reflector, and to
maintain it.
The bottom line, Harris said, is that there are many possible
ways of avoiding the dinosaurs' fate so long as we detect the
danger in time and can reach the asteroid. "Any other means
one might contemplate, say mass drivers or whatever, would also
demand rendezvous and landing on the asteroid," he said.
"All these are major engineering challenges, even if we have
the needed technology. It's more than just keeping a couple of
spare ICBMs around; it's a really major technological project,
likely bigger than the Apollo moon program."
There is no reason to lose heart, however. "If we were faced
with the threat of an asteroid impact," Harris said, "I
expect we could rise to the challenge. There is nothing
inherently `impossible' in the context of present
technology."
This story ran on page C21 of the Boston Globe on 3/18/2003.
© Copyright 2003 Globe Newspaper Company.
=============
(2) VERY LARGE METEORITE FELL DOWN IN SIBERIA
>From Pravda, 18 March 2003
http://english.pravda.ru/society/2003/03/18/44571.html
The falling of the meteorite is still mysterious. Scientists say
that it might weigh 60 tons
The night was rather dull in the north-east of the Russian
Irkutsk region on September 25, 2002. All of a sudden, night
turned into day. A very bright glow covered the sky, it was hard
to look at it. Those people, who happened to be outside at 2
a.m., saw a ball of fire that was flying very fast across the
sky. Weird rusting sounds could be heard. A few seconds later the
glow disappeared in the north-east. A little bit later, there was
a powerful blast from the distance, where the ball fell.
People learned of the Vitimsky meteorite only a week after it
fell down 700 kilometers off the Siberian city of Irkutsk. The
bright polar streamer in the sky made people think that the woods
were shining with radiation. Local residents sent a facsimile
message to the Irkutsk Institute of Sun and Earth physics of the
Russian Academy of Sciences. People asked scientists to explain
the strange phenomenon that happened in their region. Gely
Zherebtsov, the director of the institute, made inquiries at
EMERCOM departments.
Rumors about the mysterious glow above the Siberian forest could
be read in almost every local newspaper for a month after that. A
couple of weeks later it was reported that an American spy
satellite detected the meteorite. The satellite registered the
space object at the moment of its brightest luminescence. The
meteorite was flying 62 kilometers above the ground. The
satellite lost the object at the height of 30 kilometers. The
satellite also determined the position data of the object as
well. According to the information from Canadian scientists, it
was the largest event of the kind that occurred above the land in
the year 2002. The Irkutsk Institute of Sun and Earth physics
decided to send an expedition to the spot, where the meteorite
fell down. The idea was supported at the Irkutsk State University
as well. A small group of Irkutsk scientists left for the
settlement of Mama - the center of the area, above which the
meteorite flew.
Eyewitnesses said that they saw very interesting and unusual
things. People said that lamps turned on in their houses for
several seconds, although there was absolutely no electric power
that night. This means that the Vitimsky meteorite can be
categorized as an electrophone one. Its flight generated a very
powerful, albeit alternating, electric field in the atmosphere.
Those people, who saw the meteorite flying across the sky, said
that they had an incredible impression of it. Someone fell down
on the ground on account of horror, someone thought that the
doomsday came.
The expedition reached the second spot, which was registered with
the satellite. It was not possible to find anything, except
several pine trees with broken tops. Explorers came to conclusion
that there was no blast over there - the meteorite fell down
somewhere farther. Unfortunately, the initial velocity of the
meteorite was not known. The committee for meteorites of the
Russian Academy of Sciences calculated that the meteorite could
weigh 60 tons, if it had the minimum initial velocity of eleven
kilometers per second. If it was really so, the meteorite, which
fell down in the Irkutsk region was even more powerful than the
one, which fell down on the Earth in 1947. The falling of the
meteorite in 1947 was considered to be one of the largest
phenomena in the 20th century.
Of course, scientists are not 100% sure of that. If the meteorite
had a greater speed, for example, 25 kilometers per hour, it is
possible to assume that there were only several kilograms left of
the space object. The falling of the Vitimsky meteorite posed a
lot of questions. First of all, all space monitoring means of the
world failed to detect a huge meteorite that was rushing towards
planet Earth. The meteorite fell down in the area, where no one
lived, so there was absolutely no damage caused. However, things
might have turned out totally different, if the falling took
place in the densely populated Europe. It seems that Russian
observing facilities turned out to be totally helpless. This
means that the humanity is supposed to make certain conclusions
about it.
Now the area of the meteorite's falling is covered with a thick
layer of snow. Irkutsk scientists plan to go to that place again
in order to takes some snow samples. The expedition is going to
happen in the nearest future, for if the snow melts, spring
waters will wash away the space dust forever.
NASA specialists said that the Shuttle of Columbia was going to
film the area of the meteorite's falling, although the tragic
crash of the shuttle brushed that opportunity aside. If
scientists determine that it was a stone meteorite (up to 95%
meteorites are referred to that class), spring waters might
change the properties of the ancient space substance. Irkutsk
scientists can not afford renting a helicopter and examining the
area from above. Every large meteorite is extremely valuable for
the abstract science, for the world outlook, for developing
measures to struggle with the danger of asteroids.
Copyright 2003, Pravda
============
(3) HAVE NO FEAR, A TSUNAMI WILL NOT APPEAR
>From Astronomy.com, 18 March 2003
http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/255onqhj.asp
Old research that has recently surfaced eases worries that a
relatively small extraterrestrial impactor could cause a
devastating tsunami.
by Vanessa Thomas
For the past decade, many scientists have worried that an
asteroid or comet could slam into one of Earth's oceans and
create a huge tsunami that would destroy coastal communities.
While kilometer-sized impactors could pose such a threat, a
recently declassified government defense study suggests objects a
few hundred meters wide do not.
"I think it is currently an overrated hazard,"
University of Arizona planetary scientist H. Jay Melosh stated
Monday at the 34th Lunar and Planetary Sciences Conference in
Texas. Melosh explained that the concern first arose at a 1993
conference in Arizona discussing the hazards of comets and
asteroids, where scientists from Los Alamos National Laboratory
proposed that ocean-impacting objects as small as 100 meters in
diameter could produce waves tens or hundreds of meters high a
thousand kilometers away.
While other researchers have repeated the warnings of
impact-induced tsunamis and agree that objects a kilometer in
size or larger are a major worry, Melosh has remained skeptical
about the tsunami-creating capabilities of smaller objects. He
presented his position at a 1995 conference and afterward was
approached by tsunami expert William Van Dorn. In 1968, Van Dorn
told Melosh, the U.S. Office of Naval Research asked him to
summarize decades of research into the wave hazards induced by
TNT or nuclear explosions in the ocean. However, the details of
his work were still classified at the time.
Late last year, Melosh and some colleagues began a hunt for Van
Dorn's report. An Internet search provided them with the title,
"Handbook on Explosion-Generated Water Waves," and a
University of Arizona librarian helped the team track down a copy
at a college library in San Diego.
The 173-page report is based on data from actual nuclear tests at
Bikini Atoll and TNT tests at California's Mono Lake. In it, Van
Dorn concludes that "no catastrophe or damage by flooding
could result from explosion waves" and wrote in the
manuscript that "this goes for bolide impacts, too,"
said Melosh.
According to Melosh, one of Van Dorn's most important points is
that explosions produce waves with periods unlike that for any
other type of wave we're familiar with. Storm waves that surfers
ride have periods from 5 to 20 seconds, while earthquake-induced
tsunamis have periods of 100 seconds to an hour. Explosion waves
have periods that are in between. Thus, Melosh writes in a
conference abstract, "our intuition from ordinary surf or
earthquake tsunami is not a good guide to the behavior of these
waves."
Van Dorn also reported that large impact-generated waves would
break on the continental shelf. "They don't get to
shore," Melosh emphasized Monday. However, Melosh added that
parts of Van Dorn's report seem to be missing because there isn't
a full explanation behind this "Van Dorn effect," as
it's called in the defense community.
For Melosh, these and other points in the Van Dorn report should
dispel worries that impactors only a few hundred of meters wide
could cause coastal devastation for humanity. The hazard, he
said, "is probably greatly exaggerated," and that
"we are not looking at a major hazard" from such small
impacts.
Melosh continued to downplay impact-related doomsday scenarios in
a second talk (given on behalf of his collaborator, Russian
scientist Boris Ivanoff, who was unable to obtain a visa for this
week's conference). In this talk, the Arizona scientist stated
that impacts do not initiate volcanic eruptions, as has been
postulated by many since the 1960s. A previous argument was that
a large object could strike a "hot spot" on Earth that
was on the verge of volcanism. "The trouble is that large
impactors are rare and hot spots are not that prevalent,"
Melosh said. "So there are not a lot of hot spots waiting to
be hit and not a lot of impactors waiting to hit them."
Therefore, the probability of this kind of impact-induced
volcanism is quite low, he concluded.
Copyright 2003, Astronomy.com
==========
(4) HEAVENLY BODIES STIR UP ROUTINE CATASTROPHES
>From Popular Mechanics, 18 March 2003
http://www.iol.co.za/index.php?click_id=143&art_id=iol1047987020904C323&set_id=1
By Graeme Addison
Legend has it that when two people get together and er... bond,
the Earth will move - at least in a metaphorical sense. Likewise,
it takes two heavenly bodies, an impactor and a target, to come
together with Earth-shattering force to form a crater. There's
nothing dreamlike about this: it happens, frequently, throughout
the solar system. Impact catastrophes are routine.
Just over two-billion years ago, a chunk of asteroid at least the
size of Table Mountain struck the landmass that is now South
Africa. It hurtled in at a speed in excess of 55 000km/h, or
about 160 times the speed of Shumacher's Ferrari in full cry.
Welcome to the realm of cosmic uncertainty and sudden impacts.
More specifically, an impact that changed the face of primeval
South Africa.
The world-famous Vredefort Dome - centred on a tiny northern Free
State dorp and now billed as the oldest and biggest asteroid
impact site on the planet - was finally accepted as a blast site
by the majority of scientists only in the mid-1990s. It is now
being proposed as a World Heritage Site (South Africa's fifth,
after Lake St Lucia, Robben Island, Sterkfontein Caves and the
Drakensberg).
Despite its obvious significance, there is still much speculation
about Vredefort. Today leading geologists are disputing whether
the impactor set the Earth's crust on edge or not - whether there
is a shear zone as if a mighty fist had punched a hole in the
crust, leaving shards of it standing upright. Yes, say the
crust-on-edge supporters; but there are others who say there is
no real discontinuity in the underlying rock formations.
Why does it matter? Well, knowing how impacts have shaped the
Earth's crust could explain many things that remain puzzling, and
perhaps aid in deep-level geological exploration. Although a
great deal is now known about crater formation, and the Vredefort
site is increasingly being studied and modelled, much remains
speculative.
The impact took place a very long time ago when the Earth was
just over half its present age, and yet it has primary modern
significance for mining. South Africa's vast semicircle of
goldfields follows the outline of the Vredefort ring.
Coincidentally, the impact area largely covered the earlier
Witwatersrand basin where gold-bearing strata had been laid down
by archaic rivers.
Experts differ about exactly how the gold came to be concentrated
so highly in this area, but the energy released by the impact
certainly had something to do with it. The strata appear to have
been thrown on edge, and erosive processes finally exposed them
as the well-known Reef at the highest point in Johannesburg. The
world's deepest mines are to be found near Carletonville, where
Anglogold is probing to a vertical depth of 3,5km in search of
the deep veins of ore that were buried so long ago.
Few South Africans are aware of this geological wonder in the
very heart of their country. Yet it has always fascinated those
in the know - the geologists, minerologists and astrophysicists
who pay attention to large rocks falling from the sky, and who
warn that it could happen again. Here they share something with
local mystics who believe the Dome is a sign from heaven
portending the worst.
According to prophecy, fire will once again rain from the sky (or
erupt from the bowels of the Earth), and we are all doomed to
burn to extinction. This might sound alarming or merely funny
depending on your view of fate. But it could indeed happen again.
Scans of our immediate environs show that dangerous Near Earth
Objects (NEOs) quite frequently stray into Earth's neighbourhood.
Some have narrowly missed in recent years, and more are
predicted.
Calculations based on the observed number of asteroids suggest
that we should expect about three craters of at least 10km in
diameter be formed on the Earth every million years. Very big
impactors are rare, but if one the size of Vredefort should hit
us, it would probably spell the end of life as we know it.
Colossal fires and tidal waves would sweep away landmarks,
killing millions if not billions immediately. Ejecta and dust
thrown from the impact zone would do the long-term damage,
darkening the skies and chilling the seas for centuries, putting
an end to agriculture and possibly disrupting the atmospheric
processes from which we draw our air.
This is what seems to have caused the mass extinction of the
dinosaurs. About 65-million years ago, an asteroid ploughed into
what is now the Yucatan peninsula of Mexico, setting in motion
the chain reactions that killed off Earth's dominant species in a
few short years. Known as the Chicxulub crater, this is regarded
as the world's third-largest.
The second largest is at Sudbury in Ontario, Canada - thought to
have been caused by a large comet. According to one study,
Sudbury produced about 31 000 cubic kilometres of impact melt,
approximately six times the volume of lakes Huron and Ontario
combined, and nearly 70 percent more than the melt at Chicxulub.
Defending Earth against these roving destructors is becoming a
political issue in the leading Western nations. Public funds are
committed to searching for NEOs and designing possible weapons to
deflect them - although it is doubtful at this stage whether the
largest and fastest could be stopped in time.
At any rate, worldwide interest in impactors (otherwise known as
bolides) has focused attention on the Vredefort Dome and is
starting to bring international tourists to the town of Parys, on
the banks of the Vaal about 120km from Johannesburg. This type of
feature is known as an "astrobleme" - a wonderfully
evocative word for an eroded impact crater.
As with many old craters, appearances are misleading. The centre
of the Vredefort Dome (also known as the Ring) looks merely like
a small- to medium-sized crater.
Many people who visit the area think that a horseshoe of low
mountains called the "Bergland", lying to the north
west of the Vaal River between Parys and Potchefstroom, is the
crater rim. It isn't: the mountains are merely what remain of a
central "upheaval dome" that formed at the core of the
crater.
The truth is far more impressive, though harder to see from the
ground. What is most likely the outermost concentric ring of the
crater itself runs from the Mondeor heights south of Johannesburg
along the ridges of the West Rand to Welkom in the Free State - a
diameter in excess of 300km. An inner ring is also visible: it's
called the Gatsrand, and you cross it when driving on the N1
through the Grasmere tollgate.
In mistaking the Bergland for the crater rim, early estimates put
the size of the Vredefort impact zone at less than 100km. This
merited inclusion in the top league of big craters, but as time
passed and geologists explored the features of this unique area,
the truth began to dawn: this was a crater of earth-shattering
proportions, and possibly the largest on record.
Recent Landsat pictures put the minimum diameter at 250km,
although there are still scientists who say the crater is no more
than 107km wide.
There has never been any shortage of hot debating topics in the
realm of meteorites and comets. In the past, the Vredefort
"structure" was thought to have been an ancient
volcano. There was even an oddball theory that the Moon had
pulled away from Mother Earth at this point, sucking up molten
rock from below the crust, but the age of the Moon (4,5-billion
years) and its size quickly ruled out this possibility.
Vredefort is newer and smaller than any feature that might have
been left by the departing Moon. In fact, evidence in the rocks
points to an impact by a space invader. With no meteoritic
fragments present after such a long passage of time, other
evidence is invoked to prove impacting. "Shock
metamorphism" - or changes in the rock due to high pressures
not found in volcanic eruptions - is a sure sign.
Imagine a stone hitting a window: the glass shatters in myriads
of splinters. In the case of impacted rocks, these "shatter
cones" appear along with melt rocks and other signatures in
zircons, quartz and feldspar grains. In the Vredefort area,
so-called pseudotachylites - melted black seams in the rock
having the false appearance of volcanism - are a sure giveaway.
The crater was blasted out of the Earth by a wandering asteroid
that detonated in the atmosphere with the explosive force of
millions of nuclear bombs and melted the crust instantly to a
depth of up to 30km.
The low dome of granite in the middle was once viewed as the plug
of cooled molten matter that had welled up from the magma
surrounding Earth's core, and the rings were described as
successive volcano rims.
Until about three decades ago, almost every large impact site on
Earth was thought to be volcanic rather than extraterrestrial in
origin. Then along came American geologist Eugene Shoemaker and
his wife Carolyn, who pains-takingly documented crater after
crater, from America to Australia and even on the Moon. They were
convinced that many terrestrial and lunar craters were due to
asteroidal impacts rather than volcanoes, but were sidelined by
research authorities and scientist peers.
The big breakthrough came when Shoemaker and a colleague, David
Levy, correctly predicted that a newly discovered comet,
Shoemaker-Levy 9, would impact Jupiter in June 1994 - and impact
it did, in 21 spectacular fragments. Clearly, major impacts could
and did occur throughout the solar system.
A meteorite is any rock that remains after an impact. The
impactor may vaporise, however, and leave no meteorite. Large
asteroids from the belt of Asteroids lying between Mars and
Jupiter are likely to vaporise when colliding with Earth, though
the smaller ones would leave a meteorite. Meteoroid is the word
to describe any solid body migrating through space on a collision
course with other bodies. Some of these take the form of smaller
swarms of bits of rock crossing the solar system.
The Vredefort impact was certainly not the biggest in Earth's
history of punishment by heavenly bodies, either. Between three
and four- billion years ago, Earth weathered a period of heavy
bombardment by passing rock fragments, large and small. Then or
perhaps later, comet "storms" also struck the earth;
comets - which are lumps of ice and dust - have been credited
with delivering liquid water in such abundance that the seas were
formed.
Comets, too, have generated their share of scientific dispute.
British astronomer Sir Fred Hoyle suggested that life on Earth
may have been seeded by comets that transported the essential
molecular materials from outer space.
Dubbed "panspermism", this idea - supported by the
discoverer of DNA, Francis Crick - is still hotly debated.
The status of Vredefort as the oldest and biggest known impact
site on Earth has recently been challenged by Dr Gary Byerly of
Louisiana State University in the US. He and his team found
evidence of an even bigger blast in the Barberton area - crossing
over to the Pilbara Block in Western Australia (the two land
masses were once joined).
Byerly says five separate rock layers containing debris ejected
from an ancient impact have been discovered and dated at
3,47-billion years old. They didn't manage to find a crater -
preserving, for now at least, Vredefort's claim to fame.
However, none of the asteroidal or cometary impacts compares with
the biggest ever, which occurred right near the beginning of
Earth's existence, some 4,5 billion years ago. It is now thought
that the Moon was formed when a huge lump of coalescing matter -
large enough to be another planet in the process of formation -
collided with the proto-Earth. From the loose agglomeration of
the two bodies, some lighter crustal matter spun off to create
the Moon.
The story of Vredefort is just one chapter in the epic of
planetary formation in our solar system, and many others.
As gravity pulls drifting dust together to create stars and
planets, the leftovers circulate as clouds of comets, belts of
asteroids and random rock fragments. As these bodies continue to
fall inwards towards us, they result in grand and terrifying
catastrophes. It will happen again - but we hope not soon.
Graeme Addison lives in Parys and is writing a popular scientific
book about the Vredefort impactor. He is the author of The Hidden
Edge: South Africa's Quest for Innovation, and White Water: the
World's Wildest Rivers.
This article originally appears in the March issue of the South
African edition of Popular Mechanics
Copyright 2003, Popular Mechanics
=============
(5) AND FINALLY: MEMES OF SUPERSTITION
>From Tech Central Station, 19 March 2003
http://www.techcentralstation.com/1051/envirowrapper.jsp?PID=1051-450&CID=1051-031903B
By Sallie Baliunas
"Meme" is a term invented by Richard Dawkins (The
Selfish Gene, 1976) based on a concept outlined by anthropologist
F.T. Cloak in 1973, and it may now inform the current debate over
global climate change.
In a deliberate parallel to genes and biological evolution, Cloak
and Dawkins have argued that information-containing entities -
memes (pronounced "meem," like dream) - much as genes,
reproduce as they are transferred among humans and mutate as
ideas change.
Memeticists are still searching to identify a meme with a
physical substrate to complete the analogy with genes. An
organism's genes are carried as instructions by four special
molecules (called nucleotides) arranged in pairs and connected
across two strands built of sugar and phosphate molecules that
twist into a helix-shaped molecule called deoxyribonucleic acid
(DNA). Some neuromemeticists speculate that the meme is the
electrical impulse of a thought, although that is too vague a
description for scientific rigor. Others (and for now I favor
this camp) argue that memes are external to the human mind (e.g.,
W. L. Benzon, Beethoven's Anvil, 2001).
In any event, memes can be viewed as the sum of ideas that
describe human culture. And so being, they have consequences -
positive, neutral or negative - that can be repeated in history.
Let's examine some important memes related to science and
weather.
Good Memes
By the latter half of the 16th Century the scientific revolution
was well underway in Europe. Nicolaus Copernicus gave it impetus
when he published De Revolutionibus, in 1543, reviving a meme
that had been forgotten for 17 centuries - the one in which
Aristarchus (280 BCE) had crazily imagined that the Sun, not the
Earth, was the center of the solar system.
In 1545, the Italian mathematician Niccolò Cardano used
mysterious negative numbers to represent something as real as
debt. In 1572, Tycho Brahe, by observing a supernova in the
constellation Cassiopeia, discovered that the celestial vault
evolved - thus challenging the assumed, eternal immutability of
the heavens. Brahe proved that comets soared beyond the moon's
realm, and constructed a catalogue of the precise positions of
about 1,000 stars. (Besides creating some beneficial memes, Brahe
was a memorable character. He lost part of his nose in duel at
the University of Rostock in 1566 and had a prosthetic fashioned
of a gold, silver and copper alloy to cover the injury. Brahe
also had a pet moose named Rix who died after accidentally
imbibing too much purloined beer.)
In 1582, the Bavarian astronomer Christoph Clavius and Pope
Gregory XIII established the Gregorian calendar to correct errors
that had accumulated over centuries because the assumed value of
the length of the day had been wrong.
In 1586, Dutch mathematician Simon Stevin wrote fractions in
decimal notation, making their manipulation easier.
And in 1590, Dutch optician Zacharias Janssen invented the
concept of the microscope.
All of these were and are consequential and beneficial memes for
society.
Bad Memes
In the same period of these enlightened memes, though, society
also became infected with a destructive one that led to the
torture and death of thousands of women. Their pain and deaths
were the response of ignorance and uncertainty to a deterioration
in the weather. To stave it off, people in Europe engaged in a
type of precautionary principle for the climate with human
sacrifice.
What was going on?
Nearly one million years ago, the Earth's climate entered an ice
age, which had not been seen in some 250 million years. That ice
age has meant roughly 100,000-year-long periods of global cold
and advancing glaciers between short periods of warmth and
retreating glaciers.
The last major glaciation receded into the current, warm relief
over 10,000 years ago. And that warm spell has propelled
tremendous human advances in population and culture. Between the
9th and 12th Centuries, especially mild climate occurred over
many regions of the world (although not simultaneously), in a
period called the Medieval Optimum or Medieval Warm Period. Some
areas were warmer then than in the 20th Century.
But by the 14th Century, the coldest period of the last 10,000
years seeped across much of the world. Again, it was neither
uniform nor was it everywhere, but this brown climate - the
Little Ice Age - did not recede in some regions until the 19th
Century.
According to climatologist Hubert H. Lamb, the decline in climate
in central and northern Europe during the Little Ice Age tended
to produce lower temperatures in all seasons and increase
fluctuations of extreme conditions, such as heat waves. The realm
of Arctic sea ice expanded southward. The frequency of severe
storms, windstorms and floods increased.
How did this end up sacrificing women?
Weather conditions were poorest in much of Europe during the
latter half of the 16th Century and persisted through most of the
17th Century. For example, the frequency and intensity of floods
of the Pegnitz River in Nuremberg rose in that time, becoming
five times more frequent than in the 20th Century, a Czech
geographer and colleagues recently noted.
That acute period's generally wetter summers, harsher winters,
frequent storms and wild fluctuations in weather brought such
blights as crop failures, marshland expansion, pasture and
farmland destruction, starvation and disease leading to animal
and human deaths. According to Lamb, England, France and the
Netherlands in the 17th Century suffered wheat prices that were
factors of three to five times higher compared to the average
across the 13th through 16th centuries. One severe frost in May
1626 froze lakes and rivers, decimated crops and wild vegetation
and was characterized by climate historian Christian Pfister as
the worst in 500 years.
The seeming reappearance of winter in the late spring of 1626 was
unusual. But to contemporary experts it was something even worse
- unnatural. And once the extreme weather was labeled unnatural,
prevailing memes drew upon fanaticism, superstition and
demonology to address climate change. Authorities of that age
insisted that sinners, primarily women, working in concert with
the Devil, could corrupt the benign weather into hyperstorms and
superfrosts with unseen, unknowable and undetectable powers; in
short, witchcraft.
While burning people alive for witchery had been practiced for
centuries in Europe, witch burnings for climate crimes escalated
in response to ignorant, mob demands on compliant authorities,
who espoused with theological certainty that only torture and
institutional murder would atone for the storm-wielding moral
reprobates.
University of York historian Wolfgang Behringer (Witchcraft
Persecutions in Bavaria, 1997) documents societal panic triggered
by catastrophic weather in the depths of the Little Ice Age. In
Germany the severe frosts that decimated crops in 1626 were
followed by human sacrifices: Behringer notes that 600 victims
were immolated in Bamberg, 900 in Wurzburg, 900 in Electorate
Mainz and 2,000 in Cologne.
That history of how destructive memes of superstition can
coincide with a time of advance in science ought to inform the
debate about climate change in this era.
Memes Today
The severe weather of the late Middle Ages has moderated as the
20th Century banished much of the cold of the Little Ice Age.
Meanwhile, the meme that held that human sacrifice would prevent
mercurial weather demons in extreme weather is also mostly gone,
in part owing to science. But not entirely.
Some modern authorities who believe in catastrophic
anthropomorphic global climate change claim the intense storms
and floods in central Europe in the summer of 2002 were related
to human burning of fossil fuels.
The facts, though, are that there was nothing unusual or
unnatural about Europe's weather, especially compared to periods
during the Little Ice Age. And computer simulations of climate
give no clear evidence that recent or future storms would
increase as a result of fossil fuel and energy use.
Recent weather catastrophes are ever-present and
naturally-occurring, and to cope with them requires economic
resources - which rely upon energy use. That, plus the meme that
respects scientific facts.
Copyright 2003, Tech Central Station
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