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


    National Geographic News, 21 December 2000

    David Morrison <>

    Adrian Jones <>

    Cosmiverse, 20 December 2000

    NASA Science News for December 20, 2000


    Andrew Yee <>

    Larry Klaes <>

    Steven Zoroaster <>

     Alexander V. Bagrov <>

     Michael Paine <>

     Ananova, 20 December 2000


From National Geographic News, 21 December 2000

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

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.


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

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

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


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

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


From David Morrison <>

Kathleen Burton Dec. 20,
NASA Ames Research Center, Moffett Field, CA
(Phone:  650/604-1731 or 604-9000)



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

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

Futher information and a pdf file of the original paper can be found at


From Adrian Jones <>


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

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
                        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:

Dr Adrian P Jones
Department of Geological Sciences
University College London
Gower Street

Tel:    0207 679 2415/2408
Fax:    0207 388 7614


Cosmiverse, 20 December 2000

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

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


From NASA Science News for December 20, 2000

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



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

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.


From Andrew Yee <>

The University of Michigan
News and Information Services
412 Maynard
Ann Arbor, Michigan 48109-1399

Contact: Nancy Ross-Flanigan
Phone: (734) 647-1853

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

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


From Larry Klaes <>

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.



From Steven Zoroaster <>

By Dr, Richardson B. Gill
464 pages 1st edition (April 2000)
University of New Mexico Press, ISBN: 0826321941
$40 From

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.


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

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.


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.



From Alexander V. Bagrov <>

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


From Michael Paine <>

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!

Michael Paine

From Ananova, 20 December 2000   
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

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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CCNet ESSAY, 21 December 2000




By Anatoly V. Zaitsev <>

Report of International Conference
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

Lavochkin Association, Khimki, Moscow Region, Russia


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



Lavochkin Association, Khimky, Moscow Region


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

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.


CCCMENU CCC for 2000