PLEASE NOTE:
*
CCNet 137/2000 - 21 December 2000
--------------------------------
Wishing all CCNet list members and online readers Happy Chanukah,
Merry Christmas
and a peaceful New Year.
--Benny J Peiser
----------------------------------------------------------------------------
-------------------
(1) GETTING SERIOUS ABOUT ASTEROID STRIKES
National Geographic News, 21 December 2000
(2) SURPRISE METEOR SHOWER EXPECTED ON WINTER SOLSTICE
David Morrison <dmorrison@arc.nasa.gov>
(3) RAS MEETING: THE GEOLOGICAL RECORD OF IMPACTS ON THE EARTH
Adrian Jones <adrian.jones@ucl.ac.uk>
(4) HMM... NASA OFFICIAL ANNOUNCES EXTRATERRESTRIAL "FOSSIL
FIND" IN
AUSTRALIAN NEWSPAPER
Cosmiverse, 20 December 2000
(5) MARTIAN MICRO-MAGNETS
NASA Science News for December 20, 2000
(6) A NAKED EYE COMET FOR CHRISTMAS 2001?
http://meteors.com/cometlinear/an_18th_magnitude.html
(7) "EARTH'S MAGNETIC FIELD WASN'T ALWAYS WHAT WE HAVE
ASSUMED"
Andrew Yee <ayee@nova.astro.utoronto.ca>
(8) SUPERMATERIALS REPEL SPACE DANGERS
Larry Klaes <lklaes@bbn.com>
(9) BOOK REVIEW: "THE GREAT MAYA DROUGHTS: WATER, LIFE AND
DEATH"
Steven Zoroaster <szoraster@zycor.lgc.com>
(10) DON'T BELIEVE THE MOSCOW TIMES
Alexander V. Bagrov <abagrov@inasan.rssi.ru>
(11) VOLCANOES *ARE* BIGGER THREAT THAN ASTEROIDS, BUT ....
Michael Paine <mpaine@tpgi.com.au>
(12) AND FINALLY: GOOD NEWS FOR VEGANS - VEGETABLES SHOW THE WAY
TO LIFE ON
MARS
Ananova, 20 December 2000
============
(1) GETTING SERIOUS ABOUT ASTEROID STRIKES
From National Geographic News, 21 December 2000
http://209.19.141.102/news/2000/12/12202000/asteroids_3452.asp
By Pat Durkin
The early space program gave us an image of Earth as a lustrous
blue pearl,
serenely sailing through space. But a more accurate metaphor
might be a
goose in hunting season, flying though a hail of bullets. Earth
orbits
amidst a swarm of potentially threatening asteroids, some large
enough to
cause a planet-wide disaster should there be a collision.
Chances of such a collision are small in the short-term, but
inevitable over
time, scientists say. The asteroid strike that ended the age of
dinosaurs
whalloped Earth 65 million years ago at what is today Mexico's
Yucatan
Peninsula. However, as recently as 1986, a dangerous asteroid
came within
six hours of striking Earth, although no one realized how close
Earth had
come to disaster until much later.
"These things have hit the earth in the past, and they will
hit the earth in
the future," warned Eugene Shoemaker, the space-probing
geologist who first
alerted the world to the danger of near-earth asteroids (NEAs)
before he
died in 1997. "The catastrophe will exceed other natural
disasters by a long
shot."
The asteroid that ended the age of dinosaurs was at least six
miles (10
kilometers) wide, but smaller asteroids can still be devastating.
Scientists
estimate that the impact of an asteroid with a diameter of one
kilometer
(0.6 miles) or more could kill at least a quarter of the world's
human
population, as well as many other life forms. Less than a century
ago a
space rock only 330 feet (100 meters) wide exploded over Siberia.
It leveled
more than a half million acres (2,000 square kilometers) of
forest.
However remote, the possibility of the end of life as we know it
has
energized the astronomical community. The search for new
asteroids, once
considered the realm of space fanatics, has become serious
science.
OUT THERE
Images of the night sky, as seen through powerful telescopes at
California's
Palomar Observatory and elsewhere around the world, are
systematically
sifted for evidence of yet undiscovered threats. Each object that
doesn't
look like an asteroid is carefully removed. The process is
painstaking.
So far only about half of the estimated 1,100 asteroids with a
potential for
a catastrophic impact with Earth have been discovered. British
astronomers
recently urged their government to become more actively involved
in the
effort.
The United States, faced with the possibility of having to head
off a
disastrous collision someday, is in the midst of NEAR
(Shoemaker-Near Earth
Asteroid Rendezvous), a year-long project to orbit Eros, the
second-largest
NEA, in order to better understand the makeup and physical
dynamics of
asteroids.
Close-up images of potato-shaped Eros show an asteroid about the
size of
Manhattan that has been bombarded many times. Some 100,000
craters more than
50 feet (15 meters) wide pock its surface. More than a million
boulders the
size of houses or larger litter the surface of Eros. The
asteroid's
consistent color suggests a uniform composition.
This information may be critical should it become necessary to
explode an
asteroid or deflect its orbit to prevent it from striking Earth
someday.
NEAR, a joint project of the National Aeronautics and Space
Administration
(NASA) and The Johns Hopkins Applied Physics Laboratory, will
conclude in
February.
ESCAPEES FROM THE BELT
Earth-threatening asteroids are strays from what is known as the
"main
belt," an elliptical ring consisting of tens of thousands of
space rocks of
various shapes and sizes in orbit around the sun between Mars and
Jupiter.
Smaller asteroids-less than 12.5 miles (20 kilometers)
wide-sometimes
migrate to unstable areas of the main belt, known as resonances.
Once within the resonances, asteroids are vulnerable to the
gravitational
pull of nearby planets-Mars, Jupiter or Saturn-which can elongate
an
asteroid's orbit. The change is sometimes enough to swing the
asteroid onto
a path that crosses Earth's orbit, setting up the possibility of
a future
collision.
Uneven warming by the sun may play a role in moving asteroids
into the
resonances. Energy reradiating from the warmed side of the
asteroid delivers
a kick in the opposite direction, similar to the recoil of a
rocket spewing
gas. Kicks over millions of years can move an asteroid's orbit
into an
unstable area.
Only a small fraction of asteroids leave the main belt, and of
those only a
small fraction moves into a potential collision course with
Earth. However,
over billions of years many asteroid objects have collided with
Earth and
left their marks with craters that can still be seen. Arizona's
Meteor
Crater, with its uplifted rock walls and scattered beads of
glass, is an
example of an asteroid impact that occurred 50,000 years ago.
However, the history of asteroid impacts isn't all bad news. One
theory
suggests that chemical components of life, including much of
Earth's water,
arrived with asteroids and comets that bombarded the planet in
its youth.
Comments? Contact Pat Durkin or the producer of the Eye in the
Sky series
Paula Willard.
Eye in the Sky is a weekly series that brings you the story
behind the
headlines using satellite imagery, remote sensing, aerial
photography, and
maps. This feature is developed by National Geographic News with
the
sponsorship of the National Imagery and Mapping Agency (NIMA) and
Earth-Info. Check out maps and imagery at http://www.earth-info.org.
============
(2) SURPRISE METEOR SHOWER EXPECTED ON WINTER SOLSTICE
From David Morrison <dmorrison@arc.nasa.gov>
Kathleen Burton Dec. 20,
2000
NASA Ames Research Center, Moffett Field, CA
(Phone: 650/604-1731 or 604-9000)
kburton@mail.arc.nasa.gov
RELEASE: 00-86AR
SURPRISE METEOR SHOWER EXPECTED ON WINTER SOLSTICE
Astronomers are forecasting a brief shower of Ursid meteors on
Thursday
night, when the Earth will hit a dense trail of dust created in
1405, before
the birth of Columbus. Excellent viewing is predicted over both
the United
States and Canada.
Dr. Peter Jenniskens of the SETI Institute, who is based at the
NASA Ames
Research Center in the heart of California's Silicon Valley, and
researcher
Esko Lyytinen, from Helsinki, Finland, have used research and
observation
skills honed during the 1999 Leonid meteor storm to make the
prediction.
The shower is expected to hit the Earth at 2:29 a.m. EST on Dec.
22 (or
11:29 p.m. PST Dec. 21).
"The normally ordinary-looking Ursids have long puzzled
researchers because
of two intense showers seen in 1945 and 1986," said
Jenniskens. "Both of
these showers lagged the passage of the comet by as much as 6
years. By the
time these meteors hit the Earth, the comet was on its way back
to the outer
reaches of the solar system, almost as far from Earth as it ever
gets."
The Ursid meteors are caused by dust particles ejected from comet
8P/Tuttle
that plunge into Earth's atmosphere. The meteors appear to come
from the
constellation of Ursa Minor (the Little Bear) close by the pole
star. In its
13.6-year orbit around the sun, comet 8P/Tuttle never ventures
inside
Earth's orbit. As a result, its meteor shower usually is
unspectacular. It
has been 6 years since the last return of the comet.
In a paper submitted to WGN, the journal of the International
Meteor
Organisation, Jenniskens and Lyytinen explain the 6-year lag of
the meteor
shower, and forecast this year's rich display. Once the
meteoroids are
ejected into space, they say, it takes as much as six centuries
before their
orbits are sufficiently changed by the planet Jupiter so they can
hit the
Earth. During that time, the particles slowly fall behind the
orbiting comet
that produces them. After six centuries, that lag amounts
to just about 6
years.
Jenniskens and Lyytinen are the first researchers to link the
cycles of
intense Ursid showers with a particular passage of comet
8P/Tuttle. The 1945
outburst was caused by dust shed in 1392, while the 1986 shower
was dust
from 1378, six centuries ago. The researchers calculate that this
year, the
Earth will pass the center of yet another trail at a distance of
only
halfway to the moon.
On Thursday, the Earth will find in its path the trail of dust
ejected in
1405, they say. The shower is expected to last 2 to 3 hours, and
possibly
reach rates of one meteor per minute. Many of these will be faint
meteors,
so observers are encouraged to go to a dark location away from
city lights
for best viewing.
This year's Ursids will provide an unexpected bonanza for
astrobiologists,
the scientists who study the origin, evolution, distribution and
future of
life in the universe. The shower will enable researchers to probe
the
composition and morphology of grains from a comet not previously
sampled.
Like the Leonid meteors, the Ursid meteoroids can be precisely
dated, but
they are different in important ways because they have spent six
times
longer in the solar system environment and plow into Earth's
atmosphere with
just half the Leonids' speed.
NASA Ames Research Center is NASA's lead center for astrobiology.
The
central administrative office of the NASA Astrobiology Institute
(NAI), a
research consortium involving academic, non-profit and NASA field
centers,
also is located at Ames. The NAI has international affiliate and
associate
members.
Futher information and a pdf file of the original paper can be
found at
http://leonid.arc.nasa.gov/leonidnews28.html
=============
(3) RAS MEETING: THE GEOLOGICAL RECORD OF IMPACTS ON THE EARTH
From Adrian Jones <adrian.jones@ucl.ac.uk>
ROYAL ASTRONOMICAL SOCIETY DISCUSSION MEETING
9 February 2001
Burlingtson House, Piccadilly Circus, London
"The geological record of impacts on the Earth".
Organisers: APJones, GDPrice, MMGrady
1000 Coffee
1025-1300 Morning session
1300-1400 Lunch
1400-1530 Afternoon session
1530-1600 Afternoon tea
1600-1800 RAS monthly Meeting
1800-1900 Drinks party at Savile Row
1025-1030 Introduction by
GDPrice (and also
Chairperson)
1030-1100
1 Evidence of the late heavy
bombardment
Christian Koeberl (Vienna)
1100-1120
2 The Chicxulub impact
structure: a review
Mike Warner (London/IC)
1120-1140
3 Chicxulub II: Nature of the
K/T projectile?
Matthew Genge (London/NHM)
1140-1200
4 Large impacts and impact
volcanism?
Adrian Jones (London/UCL)
1200-1220
5 Timing between flood
basalts and impacts.
Simon Kelley (MKeynes/OU)
1220-1240
6 Holocene Impacts and the
Difficulties of Detection
Benny Peiser(Liverpool/JMU)
1240-1255
7 Simulation of terrestrial
shock metamorphism
Emma Bowden (UCL)
1255-1300
Open Discussion
Afternoon session : (Monica Grady Chairperson)
1400-1415
5 The flux of
extraterrestrial material to the Earth'
Phil Bland (Open University)
1415-1430
6 NEO-uniformitarianism: are
impacts random in time?
Duncan Steel (Salford)
1430-1500
7 Regularities in impact
records; possible cometary
causes
Bill Napier (Armagh Observatory)
1500-1515
8 Origins of impactors
Mark Bailey (Armagh Observatory)
1515-1530
9 possible space for
discussion
for further information please contact Adrian Jones (email:
adrian.jones@ucl.ac.uk)
Dr Adrian P Jones
Department of Geological Sciences
University College London
Gower Street
London
WC1E 6BT
Tel: 0207 679 2415/2408
Fax: 0207 388 7614
email: adrian.jones@ucl.ac.uk
website: www.ucl.ac.uk/geolsci/research/petrology
==============
(4) HMM... NASA OFFICIAL ANNOUNCES EXTRATERRESTRIAL "FOSSIL
FIND" IN
AUSTRALIAN NEWSPAPER
Cosmiverse, 20 December 2000
http://www.cosmiverse.com/space122005.html
Australia's Herald Sun newspaper reported Monday that alien life
has been
discovered in a meteorite that fell to Earth in the morning hours
of
September 18, 1969. The meteorite rained down in pieces over the
Victorian
town of Murchison.
Announcing the discovery was Professor Richard Hoover, head of
NASA's
astrobiology unit at the Marshall Space Flight Center. Hoover
told the
Herald Sun that he had strong evidence of bacterial cells. Hoover
also told
the newspaper they looked very similar to meteorites found in
Antarctica,
other extreme Earth environments and other rare meteorites.
Hoover credits this new discovery - which could give clues to the
origin of
life in the solar system - to new technology.
Scientists believe that the 4.6 billion-year-old meteorite may
have broken
from a comet or asteroid some 800,000 years ago, before it
dropped from the
sky into the central Victorian town.
In order for NASA to further research Hoover's claims, he had to
acquire
more samples. Therefore, he traveled to the Museum of Victoria to
make his
plea. The museum agreed to donate eight more samples of the
meteorite.
NASA is currently studying about six meteorites Prof. Hoover
believes hold
microfossils. While in Australia, Hoover stopped off at Melbourne
University's Summer School of Science, where he showed an
audience
photographs of structures that he believes are organisms
"indigenous" to the
meteorite.
Prof. Hoover pointed out that the remarkable similarities between
Earth
micro-organisms and the alien forms could come from several
factors:
Primitive life began somewhere else in the solar system and a
comet or
asteroid seeded this planet.
Life began on Earth but a huge impact early on sent up fragments
of ice and
sedimentary rock into space where it was collected by comets.
Some of
Hoover's findings have been published in the Journal of
Paleontology.
Despite the highly controversial nature of his claims, Hoover
understands
and is prepared for any disagreements by scientists.
"I have found doing the research a whole sweep of large
structures that I am
convinced are biological structures within carbonaceous
chondrites," Hoover
told the Herald Sun. Carbonaceous chondrites are meteorites with
a lot of
carbon in them. "There is a whole sweep of very, very
incredible
microfossils in Murchison," he added.
Hoover continued by telling the newspaper, "There is, in my
opinion, strong
evidence of biogenecity in meteorite cores. We have evidence of
cell walls,
things that look like cyanobacteria and purple sulphur bacteria.
We see
evidence of structures similar to organisms that live in
Antarctica."
The astrobiologist left for home on Sunday, carrying with him
eight more
samples of the meteorite donated by the Museum of Victoria in
sealed vials.
Copyright 2000, Cosmiverse
==============
(5) MARTIAN MICRO-MAGNETS
From NASA Science News for December 20, 2000
http://science.nasa.gov/headlines/y2000/ast20dec_1.htm?list20392
The Allan Hills meteorite from Mars is peppered with tiny
magnetic crystals
that on our planet are made only by bacteria.
December 20, 2000 -- The case for ancient life on Mars looks
better than
ever after scientists announced last week that they had
discovered magnetic
crystals inside a Martian meteorite -- crystals that, here on
Earth, are
produced only by microscopic life forms.
The magnetic compound, called magnetite or Fe3O4, is common
enough on our
planet. It is present, for example, in household video and audio
tapes. But
only certain types of terrestrial bacteria, which can assemble
the crystals
atom by atom, produce magnetite structures that are chemically
pure and free
from defects.
Scientists studying the Allan Hills meteorite, a
4-billion-year-old rock
from Mars that landed in Antarctica about 13,000 years ago, found
just such
crystals deep inside the space rock.
"Finding this type of magnetic crystal in any material from
another planet
is an amazing and important finding," said Dr. Dennis
Bazylinski, a
geobiologist at Iowa State University. Bazylinski leads one of
the few labs
capable of culturing these magnet-producing bacteria, which are
common in
many freshwater and marine environments on Earth.
Bazylinski was one of nine researchers conducting the four-year
investigation, which was funded by NASA's Astrobiology Institute.
A report
of their research is in the December issue of the journal
Geochimica et
Cosmochimica Acta.
"We're not claiming that this is proof of life on
Mars," said Dr. Everett
Gibson, an astrobiologist at NASA's Johnson Space Center in
Houston, Texas,
who also participated in the study.
"What we're claiming is that these magnetites (from the
meteorite) are
basically indistinguishable from certain biogenic (i.e.,
biologically-produced) magnetites on Earth. And furthermore, we
know of no
other mechanism to make them, either on Earth or Mars,"
Gibson said.
The scientists believe that these crystals traveled from Mars in
the
meteorite, rather than being produced on Earth by bacteria that
contaminated
the meteorite after it arrived in Antarctica.
"That was a real concern -- whether (the magnetite crystals)
could be
terrestrial contamination," Gibson said. But several facts
support a Martian
origin, including the deep embedding of the crystals in the
carbonate
material of the meteorite and the preference of the
magnetite-producing
bacteria for low-oxygen environments, making it unlikely that
such bacteria
would live where the meteorite was found.
"We looked at it very carefully and convinced ourselves that
the magnetite
had to be from Mars," Gibson said. "No one (in the
scientific community) is
really questioning that."
This meteorite -- called the Allan Hills meteorite after the
Antarctic ice
sheet where it was found -- is the same one that caused a stir in
1996 by
providing the first potential evidence of bacteria-like life on
Mars. These
magnetite crystals were one of the four pieces of evidence from
the
meteorite that supported the '96 announcement. But little was
known about
the specific traits of bacteria-produced magnetite then.
"At that point, we just knew that there were tiny magnetite
crystals made by
bacteria, and we didn't know much about them," Gibson said.
"And we now have
studied (the crystals) in detail, and ones known to be made by
bacteria have
the same properties (as those from the meteorite)."
Crystals made by magnetite-producing bacteria are chemically pure
and free
from defects in the crystalline structure. They are slightly
elongated along
a particular crystalline axis, and they range in size from 35 to
120
nanometers (a nanometer is one-billionth of a meter). They also
show a
particular pattern of faceting -- like a cut diamond. These
properties are
so unusual that they have only been seen in magnetite crystals
produced by
biological processes.
The researchers discovered that about one-fourth of the magnetite
crystals
in the meteorite have these exact properties. The other
three-fourths of the
crystals are assumed to have formed geologically, researchers
said.
Bacteria are able to make such precise crystals because they
control the
construction of the crystal at an atomic level.
"The magnetites are grown atom by atom inside the bacteria.
The bacteria
form a little membrane around the crystal that controls the
growth of the
magnetite, and then they pump iron atoms into that membrane and
form these
crystals (which consist of iron and oxygen atoms). By carefully
controlling
crystal growth with the membrane, the bacteria keep the crystals
from
growing in one direction and allow them to grow in another,"
Gibson said.
The direction in which the bacteria elongate the crystals
maximizes the
magnetic strength of the magnetite. The bacteria, which are
mostly from the
Magnetospirillum genus, then line up several of these crystals to
collectively act as a bar magnet, which allows the bacteria to
align itself
with Earth's magnetic field.
Why would a bacterium want to line up with our planet's magnetic
field? It
turns out that such behavior can help an aqueous microbe find
water with the
right mix of oxygen. Generally, differing concentrations of
oxygen in a body
of water are arranged in horizontal layers, like the floors of a
building.
Earth's magnetic field lines, in addition to pointing toward the
pole, also
make a vertical angle with the ground. These lines provide a sort
of slanted
"elevator shaft" that help the bacteria search the
"building's floors,"
which can be more efficient than an aimless search.
But such an internal compass would be of no use to a Martian
bacterium
unless Mars had a natural magnetic field like Earth does.
"When we first wrote the original paper in '96, it was
thought that Mars had
never had much of a magnetic field," Gibson said. "But
then the Mars Global
Surveyer detected a very strong remnant magnetism in some of the
rocks in
the crust of Mars. ... So it's clear that early on, Mars had a
strong
magnetic field, and that's about the time we think these
magnetites were
formed: about 3.9 billion years ago."
In contrast, the earliest well-documented life on Earth dates
back to
between 3.6 and 3.7 billion years ago, Gibson said. Both planets
formed
about 4.5 billion years ago.
"Now we are trying to answer the question of whether
(magnetite-producing)
bacteria could have actually lived on Mars," Bazylinski
said. "And we have
found certain aspects of their metabolism which suggest that they
might have
been able to do so."
The journal Science recently published research showing evidence
of
widespread sediment layers on Mars, which the researchers
interpreted to be
the product of ancient lakes that once dotted Mars's surface.
Because these
lakes may have provided a habitat for bacteria, this finding
supports the
possibility that the bacteria may have existed on Mars,
Bazylinski said.
Though the new evidence from the Allan Hills meteorite does not
prove that
life once existed on Mars, Gibson said that, "We think it's
evidence that is
hard to explain by any other hypothesis."
In addition to Bazylinski and Gibson, the scientists involved
with this
investigation are Kathie Thomas-Keprta, Simon Clemett, and Susan
Wentworth
from Lockheed Martin at Johnson Space Center; David McKay at JSC;
Joseph
Kirschvink at the California Institute of Technology; H. Vali at
McGill
University, Montreal; and Christopher Romanek at Savannah River
Ecology
Laboratory.
=========
(6) A NAKED EYE COMET FOR CHRISTMAS 2001?
From http://meteors.com/cometlinear/an_18th_magnitude.html
Posted 12/20/00 | by Dr. Mark Kidger
An 18th magnitude "asteroid" first detected by the
LINEAR Telescope on
November 16th, but later shown to be a distant comet, could
become a naked
eye object in November and December 2001. An estimate based on
its current
brightness suggests that it could reach about magnitude 4.5 by
late November
2001, but could do better if it is a new comet and brightens
rapidly
initially.
The object, designated 2000 WM1, was at about 6AU (900 million
kilometres)
from the Sun - well beyond the orbit of Jupiter when
discovered. With a
full month of observations available to calculate the comet's
orbit it
should show very little change even as new data arrive. The
comet, now named
Comet C/2000 WM1 (LINEAR), will reach perihelion around 18:30UT
on January
22nd 2002, at 0.555AU (83 million kilometres) from the Sun.
Initially the comet will be a northern hemisphere object only.
However, in
early December 2001 it will pass quite close to the Earth
(0.32AU, or 49
million kilometres) and, around this time will cross rapidly to
the southern
hemisphere. At the time of closest approach it will be close to
opposition
and visible almost all night.
An estimate of its brightness suggests that it is of about
average size
perhaps 3km in diameter and that its average magnitude, that
is, the
brightness that it would have if it were simultaneously 1AU (150
million
kilometres) from the Sun and the Earth, is 6.5. This is 10 times
fainter
than Comet Halley and nearly 1000 times fainter than Comet
Hale-Bopp, but
comparable with 1996¹s beautiful Comet Hyakutake.
If it were to behave like an average comet, it might be expected
to reach
magnitude 4.6 by mid-December 2001. This is bright enough to be
easily
visible to the naked-eye from a dark site. However, if it is a
new comet and
brightens rapidly initially, it could even be significantly
better than
this. A new comet often has a layer of very volatile carbon
monoxide ice on
the surface of its nucleus. This ice coating sublimes violently
at a large
distance from the Sun, making the comet brighten very rapidly -
at least
initially - although close to the Sun such comets "slow
down" considerably.
The comet should be visible continuously through perihelion as it
recedes
from the Earth, although it will only be visible from the
southern
hemisphere during January 2002. After perihelion it will move
back north. At
perihelion it may be as bright as magnitude 4.0, but will fade
rapidly
afterwards. During late December and early January 2001-2002 the
comet will
be almost side-on to the Earth, showing the maximum extent of its
tail in
the sky.
Although no comet can be relied upon completely, there is a very
good chance
that Comet C/2000 WM1 (LINEAR) will be a naked-eye Christmas
comet for 2001.
===========
(7) "EARTH'S MAGNETIC FIELD WASN'T ALWAYS WHAT WE HAVE
ASSUMED"
From Andrew Yee <ayee@nova.astro.utoronto.ca>
The University of Michigan
News and Information Services
412 Maynard
Ann Arbor, Michigan 48109-1399
Contact: Nancy Ross-Flanigan
Phone: (734) 647-1853
E-mail: rossflan@umich.edu
News Release: December 19, 2000 (11)
Study solves Pangea puzzle
SAN FRANCISCO -- Researchers at the University of Michigan and
the
Geological Survey of Norway say they have solved a longstanding
and
controversial puzzle over the position of Pangea, the ancient
supercontinent
that began breaking up some 200 million years ago to form today's
continents. They presented their findings Dec. 19 at a meeting of
the
American Geophysical Union here.
Scientists have long known that the continents are not fixed in
place on
Earth's surface, but gradually change positions over millions of
years.
Based on geological evidence, researchers have come up with
several models
that show how the continents might have fit together when they
were tightly
clustered. One widely accepted model, dubbed Pangea A and
reproduced in
countless textbooks, shows what is now South America nestled
against the
southern edge of North America, with Africa just east of South
America,
adjacent to the Atlantic coast of North America and southwest of
Europe.
But geologists who study paleomagnetic data -- records of Earth's
magnetic
field captured in rocks over eons -- have been troubled by data
that just
don't fit the Pangea A model. Paleomagnetic data reveal the
latitude at
which rocks were located when the magnetization was recorded.
That
information, in turn, provides clues to the positions of the
continents.
The problem is that, according to the paleomagnetic data,
"the southern
continents should be a little bit farther north" than they
are in the Pangea
A model, explains Rob Van der Voo, a professor of geological
sciences at
U-M. That dilemma has led to alternative models that place
northwestern
South America along the east coast of North America or push it
even farther
east to lie just south of Europe. While the revised models may
satisfy
researchers who specialize in paleomagnetism, they gall other
geologists who
find no evidence in fossils or mountain chains to suggest that
the
continents have ever been in those positions.
Now, Van der Voo and colleague Trond Torsvik of the Geological
Survey of
Norway have found a way to reconcile the paleomagnetic data with
the
classical Pangea A model. The key, they say, lies in assumptions
about
Earth's magnetic field. Scientists generally have assumed the
field is like
that of a dipole, an object such as a bar magnet, with north and
south
magnetic poles. That view is not exactly correct -- the field
does have some
non-dipole components today -- but because those components vary
from
century to century, they have been presumed to cancel out over
long spans of
time.
But suppose, says Van der Voo, "that the main magnetic field
wasn't what we
have always assumed as perfectly dipolar -- that there was a
longstanding
non-dipolar field that did not get averaged out." If that
were true,
positions indicated by paleomagnetic data would be slightly
different from
those that assume a purely dipolar field. Sure enough, when Van
der Voo and
Torsvik performed an analysis they found long-term non-dipole
fields, and
inclusion of these fields produced a near perfect continental fit
with the
Pangea A model.
"The broader implications of this study," says Van der
Voo, "are that
paleomagnetic results for other times and other continental
configurations
must now be re-evaluated with the new geomagnetic field model
that should
include some 10 percent non-dipole fields, and this will keep us
busy for
decades."
==========
(8) SUPERMATERIALS REPEL SPACE DANGERS
From Larry Klaes <lklaes@bbn.com>
A spacecraft takes a hole-making hit from a meteoroid and repairs
itself.
Huge but super-thin solar sails en route to Alpha Centauri are
imbedded with
rip-stopping carbon nanotubes. Human waste is used as a
death-defying way to
shield Mars-bound astronauts against lethal blasts of radiation.
FULL ARTICLE at:
http://www.space.com/businesstechnology/technology/selfhealing_craft_001208.html
===========
(9) BOOK REVIEW: "THE GREAT MAYA DROUGHTS: WATER, LIFE AND
DEATH"
From Steven Zoroaster <szoraster@zycor.lgc.com>
THE GREAT MAYA DROUGHTS: WATER, LIFE AND DEATH
By Dr, Richardson B. Gill
464 pages 1st edition (April 2000)
University of New Mexico Press, ISBN: 0826321941
$40 From Amazon.com
This book's central thesis is that Classical Maya civilization
collapsed as
a result of a drought in Mesoamerica extending throughout the 9th
century
AD. This particular drought was the local manifestation of
Northern
Hemisphere weather patterns that the author asserts have been
repeated
frequently over shorter time periods for thousands of years, even
into this
century, and which nearly always produce drought in Mesoamerica.
Once you accept Dr. Gill's evidence for Mesoamerican droughts and
their
regularity, that evidence provides a parsimonious explanation for
the end of
Classical Maya civilization. After reading this book, I think
many people
will accept the evidence and the explanation.
There are, of course, more complex explanations, including
overpopulation,
over centralization, warfare between Mayan city-states, external
invasion,
disruption of long distance trade networks, disease, exhaustion
of the
environment, and peasant revolt. Mr. Gill argues that these are
not needed
to explain the collapse. This does not mean that such factors did
not
influence the course of events, just that the collapse would have
happened
because of the drought alone.
To support his thesis, which is clearly stated clearly at the
beginning of
the book, Dr. Gill takes the reader on a tour of a multitude of
scientific
disciplines. Each discipline studied adds information about the
importance,
frequency, possible causes and consequences of drought in
Mesoamerican and on civilization and population trends throughout
the world.
Any one of these tours alone is worth the price of the book,
since they are
extremely well written and provide the foundation for further
study on each
topic covered.
Foundations
In a chapter titled "Geology, Hydrology, and Water,"
the author describes
the geology and hydrology of the Yucatan and the Maya highlands
and the
major drainage basins, and provides an extensive discussion of
the water
supply problem and how it was managed in the pre-Columbian
period.
The basic geology is the standard stuff: seasonal rainfall,
permeable
limestone, karstic drainage, deep underground fresh water usually
inaccessible, except in the north through cenotes and along the
east cost
from freshwater lakes or lagoons. But, this chapter also
explained how the
Maya adapted to this environment. For example, the author
describes natural
surface depressions used as water reservoirs and known as
aquadas. The Maya
paved many of these
small depressions and some were provided with chultunes, bell
shaped
chambers excavated below the aquada bottom to capture additional
water when
the aquada was filled. (A single chultun could hold 30,000 liters
of water,
enough to comfortably supply drinking and cooking water for
twenty-five people for one year).
In fact, Mayan city-states and even smaller settlements were
designed with
water management a primary consideration, with central
reservoirs,
residential reservoirs, canals, and the terrain and pavement of
the city
itself all engineered to facilitate the collection and storage of
water during the wet season. This was important, because, as
explained in a
chapter on "Paleoclimatology," small-scale (relative to
the great final
calamity) droughts were endemic to the Maya area as shown both by
Maya water
management strategies and more recent evidence from sediment
recovered from
the bottom of lakes. Records during the Spanish colonial period
point to further famines on a regular basis after the conquest.
In fact,
during the colonial period, population looses from drought in the
Yucatan
ranged up to 30 or 40%.
In another chapter titled "Volcanoes and Weather" Dr.
Gill argues that there
is a strong correlation between the eruptions of large volcanoes
around the
world, and the worldwide weather patterns that lead to drought in
Mesoamerica. This particular chapter not only provided evidence
to support
this correlation, but evidence that the volcanoes may have been a
forcing
mechanism for those weather patterns. Volcanoes and weather are a
topic of
some interest to me, and until I read this book, I had trouble
finding a
good introduction to the study of volcanoes, and to the
relationship between
volcanoes and weather. Now I have.
To save space and my own energy, I am not going to discuss the
chapter on
"Thermohaline Circulation." Except, I will say that
that I learned enough in
that one chapter on North Atlantic deep water formation and three
dimensional ocean circulation models for all of the world's
oceans to help
me understand an article on the subject recently published in the
journal
Nature. I will also skip over the early chapter titled
"Self-Organization"
which discusses, among other things, the overall flow of energy
in a
civilization, and the important roll of exporting entropy to the
environment by a civilization to reduce the potentially
disruptive entropy
in the civilization; and over the chapter titled "Famine and
the Individual"
which describes how famine can rapidly lead to the complete
collapse of
social norms and the massive disruption of "normal"
energy flows in any
civilization.
But What About Chichen Itza?
Probably the most important or challenging single assertion Dr.
Gill makes
is changing the timing of the collapse of Chichen Itza.
Traditionally dated
around 1150 AD, and cited as an example of the ability of some
Maya cities
to survive the Classical collapse, the author re-dates this event
to the 9th century based partly on re-interpretation of inscribed
calendar
dates attributed to the period after the collapse. This
particular assertion
is probably one of the most controversial in the book and is
critical to the
author's basic thesis. I suspect that it will be the focus of
considerable
argument. In support of this claim, the author provides a new
interpretation
of the relationship between Chichen Itza and the Toltecs, which
itself is
probably worth a fair amount of discussion.
Recommendations
I strongly recommend this book to just about anyone with an
analytical mind.
If you are interested in the general flow of Maya civilization
this book has
a lot to offer. If you are generally interested in the interplay
between
climate and civilization, this book also has a lot to offer. If
you are just
somewhat interested in topics such as global meteorology,
volcanoes, tree-ring records in Europe and America, or the debate
between
uniformitariansm and neocatastrophism in the early study of
geology, you
will still find useful information that is readily accessible.
============================
* LETTERS TO THE MODERATOR *
============================
(10) DON'T BELIEVE THE MOSCOW TIMES
From Alexander V. Bagrov <abagrov@inasan.rssi.ru>
Dear Sir,
The Moscow "paparazzi" spread uncorrect information
that I claimed a 1000
meter asteroid had destroyed Phaeton. It was 1000 KILOmeter!
So huge bodies can be detected at distance of some astronomical
units
(1AU=150,000,000 km) - some months before possible collision. But
there are
less then 1,000,000 so objects in the outer regions of the Solar
System, and
probability of collision is not more than 1 in some billion
years.
Not so large asteroid, say, about some meters or some hundred
meters in
diameter, can produce disaster as heavy as H-bomb can do. This
kind of
asteroid, astronomers can detect not earlier than befour 2-4 days
of
possible collision, at distance about some million km. It does
not mean that
we can detect any dangerous object becouse we can observe only
narrow part
of night sky. So Russian scientists designed a Space Object
Survey devoted
to early alarm.
I am sorry that jounnalists misunderstanded my ideas.
Sincerely Yours,
Alexander V.Bagrov
===========
(11) VOLCANOES *ARE* BIGGER THREAT THAN ASTEROIDS, BUT ....
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
I have done some very rough calculations on the relative threat
between NEO
impacts and volcano eruptions that are large enough to cause
global climatic
perturbations. The average interval worked out at about 20,000
years and
2,000 years respectively so, by this crude method volcanoes
are more of a threat than asteroids.
I can understand volcanologists becoming a little frustrated that
asteroid
"scares" seem to grab the headlines but, on the other
hand, it would be
great if worldwide funding for Spaceguard managed to reach one
tenth of that
for the study of volcanoes!
regards
Michael Paine
===============
(12) AND FINALLY: GOOD NEWS FOR VEGANS - VEGETABLES SHOW THE WAY
TO LIFE ON
MARS
From Ananova, 20 December 2000
http://www.ananova.com/news/story/sm_150096.html
Vegetables show the way to life on Mars
Scientists in New Zealand have successfully grown the first
vegetables in
Martian soil.
The tiny asparagus and potato plants were grown in soil taken
from Martian
meteorites which landed on Earth thousands of years ago.
The scientific breakthrough raises hopes that humans may one day
be able to
colonise the Red Planet.
Lincoln University chemistry research professor Dr Michael
Mautner has
carried out the vegetable-growing experiments in soil taken from
the Dar al
Gani 476 meteorite which was found in the Sahara Desert in Libya
in 1998,
and the Murchison meteorite discovered in Australia in 1969.
Dr Mautner says the Martian soil showed surprisingly high levels
of
phosphate, ideal for growing healthy vegetables, the New Zealand
Herald
reports.
He is now convinced that one day, humans will live on Mars. Dr
Mautner said:
"If we build colonies in space we will have to grow plants
for food so
obviously we need to know the soil can support that.
"Everyone knows the future is out there in space, so it's
exciting.
Space-based soils could potentially support future human
expansion in the
solar system. I wouldn't say very soon, but in a few
centuries."
Copyright 2000, Ananova
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-----------------------------
A RUSSIAN VIEW ON THE IMPACT HAZARD AND PLANETARY DEFENSE
---------------------------------------------------------
I. SOME OF PROBLEMS AND SEQUENCES
OF DEVELOPMENT OF THE PLANETARY DEFENSE SYSTEM
II. POSSIBLE ARRANGEMENT AND
PHASES OF DEVELOPMENT OF THE PLANETARY DEFENSE SYSTEM
By Anatoly V. Zaitsev <zav@berc.rssi.ru>
Report of International Conference
"SPACE PROTECTION OF THE EARTH - 96"
("SPE-96")
September 23-27, 1996
Russian Federal Nuclear Center
All-Russian Research Institute of Technical Physics
Snezhinsk (Chelyabinsk-70)
Russia, 141400,
Tel.: (095) 575-5859
Moscow region, Khimki-2
FAX: (095) 573-2584
Leningradskoe shosse., 24
E-mail: zav@berc.rssi.ru
SOME OF PROBLEMS AND SEQUENCES OF
DEVELOPMENT OF THE PLANETARY DEFENSE SYSTEM
ANATOLY V. ZAITSEV
E-mail: zav@berc.rssi.ru
Lavochkin Association, Khimki, Moscow Region, Russia
INTRODUCTION
Between a diversity of dangers, menacing to existence of a
mankind, the
possible consequences of impacts of asteroids and comets with the
Earth are
considered recently by a sufficiently serious manner. It became
evidently,
that a collision with an object few kilometres of size could
result
destruction, in fact, of all lives on our planet [1¸3].
However, a threat can be provided not only by large-scale
objects, a
probability of collision with which is sufficiently low, but also
relatively
small objects of the Tunguska meteorite type. This is due to the
current
abundance of the Earth with potentially dangerous technogenous
objects. It
refers to nuclear objects, chemical plants, toxic wastes
storehouses, etc.
Destruction of any of them in the case of the asteroid impact can
result not
only the human victims and hardware damages, but also became as a
peculiar
"trigger" for development of the ecological crisis or
nuclear conflict.
Increased understanding of degree of the danger of such
developments and
their effect on the stable mankind development provides a
necessity to take
measures in order to avoid such catastrophes or decrease damages
from them.
Their necessity is confirmed by recently conducted studies and
analyses
which showed, that the contemporary level of the technological
development
of the word leading countries allows to proceed to creation of
the Planetary
Defense System (PDS) aimed against the meteor and asteroid danger
[4¸9].
Meanwhile, where are quite, and it is necessary to recognise,
well-proven
thoughts, that the PDS could be used not only for the mankind
rescue, but
also as a mean for destruction of entire countries and regions
[10].
Whole our historical experience argues that this is quite
possible. Perhaps
it is impossible to find neither technical human hands creature,
which was
not harmful for him. Moreover, the scales of possible disasters
in the case
of the PDS use for military purposes could not be compared with
those we
have had in the past.
Taking into account particularities of above anxieties, this
paper contains
an attempts to reveal some of potentially hazardous problems and
consequences of the PDS development. Moreover, the main reason,
according to
which a main emphasis is laid mainly on the analysis of the
negative
occurrences, is a necessity to develop measures with the aim of
their
non-admission.
[continued]
POSSIBLE ARRANGEMENT AND
PHASES OF DEVELOPMENT OF THE PLANETARY DEFENSE SYSTEM
A. V. ZAITSEV
E-mail: zav@berc.rssi.ru
Lavochkin Association, Khimky, Moscow Region
INTRODUCTION
In fact at present there is no doubt about the existence of real
danger
originated from the asteroids and comets impacts with the Earth,
that
threatens its biosphere, so this circumstance does not require
additional
arguments.
Earlier conducted works [1-4] show that the up-to-date levels of
development
of technologies allow to proceed already to the practical
realization of
measures, providing the protection against this danger.
This work develops and adds some conditions related to the
earlier proposed
principles of construction of the Planetary Defense System (PDS)
aimed to
protect against asteroids and comets. Use of the term
«planetary» in the
name is explained by the fact, that this system will be used to
defend not
only of the Earth, but also other bodies of the Solar System, and
the Moon
in the first place. It will be necessary not only for protection
of the
lunar colonies, but for preventing of the consequences of the
great bodies
impacts with the Moon, that are probably unfavourable for the
Earth's
population. For instance, a possibility of the great fragments
falling on to
the Earth, pollution of the near-terrestrial space, change of the
Moon's
orbit could be referred to these effects.
The approach to the PDS architecture, which is proposed below, is
based on
the utilization of already existing, mainly rocket/space
technologies.
Obviously, that with the appearance of new science and technology
achievements, the PDS and means of configurations used will be
essentially
upgraded and the System will have more capacity for the defense
against such
space danger.
[continued]