PLEASE NOTE:
*
CCNet 69/2001 - 18 May 2001
----------------------------
"The Maya were talented astronomers, religiously intense in
their
observations of the sun, moon and planets. Now, new research
shows
something in the heavens may have influenced their culture and
ultimately
helped bring about their demise."
--Aaron Hoover, University of Florida, 17 May 2001
"A handful of entrepreneurs have set their sights on some
heavenly
dividends, whether by strip mining the moon for energy,
extracting
platinum from asteroid mountains or distilling water from dormant
comets.
In the past those hoping to transform the final frontier into
cosmic cash
have drawn mostly snickers. But in recent years such mavericks
have elicited
something else -- respect and funding from major industries and
governments
in the usually exclusive club of space exploration. [...] The
first places
where humans could strike it rich in space are a handful of
asteroids
near Earth, composed almost completely of valuable metals: iron,
nickel, gold, platinum. In particular, the asteroid Amun, a
mountain of
natural stainless steel mixed with precious metals, contains 30
times as
much metal as humans have mined and processed throughout history,
John
Lewis said. The smallest of dozens of known metallic asteroids,
it
would be worth at least an estimated $20 trillion based on
current
market prices."
--Richard Stenger, CNN, 16 May 2001
"Anyone who owns a mega-yacht or large jet can afford their
own
planetary deep space mission."
--Jim Benson, Founder of SpaceDev, 16 May 2001
"A comet that shattered on its approach to the Sun breathed
new life
into the theory that comet impacts provided most of the water in
Earth's
oceans. The same NASA observations of the comet, designated
C/1999 S4
LINEAR (LINEAR), also support the idea that comet impacts
furnished a
significant amount of the organic molecules used in life that
later arose on
Earth."
--Mark Hess, Goddard Space Flight Center, 17 May 2001
(1) SEEKING EL DORADO IN SPACE
Larry Klaes <larry.klaes@incent.com>
(2) ASTRONOMERS PUZZLED OVER COMET LINEAR'S MISSING PIECES
Andrew Yee <ayee@nova.astro.utoronto.ca>
(3) DYING COMET'S KIN MAY HAVE NOURISHED LIFE ON EARTH
Mark Hess <mhess@pop100.gsfc.nasa.gov>
(4) BREAKING UP IS HARD TO DO, EVEN FOR A COMET
Ron Baalke <baalke@jpl.nasa.gov>
(5) SOHO'S UNIQUE VIEW OF A COMET THAT FELL TO PIECES
ESA Science News, 18 May 2001
(6) CHANGES IN SUN'S INTENSITY TIED TO RECURRENT DROUGHTS IN MAYA
REGION
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) PYRAMIDS, FLIGHT ORIENTATED METEORITES AND BA NE-PE.
Matthew Genge <M.Genge@nhm.ac.uk>
(8) RE: EJECTED DINOSAUR RELICS
S. Fred Singer <singer@sepp.org>
(9) AND FINALLY, NO END TO END-TIME PROPHECIES: "MUTANT
BACTERIA BIOWARS
THREATEN APOCALYPSE NOW"
SMH.com, 17 May 2001
==============
(1) SEEKING EL DORADO IN SPACE
From Larry Klaes <larry.klaes@incent.com>
CNN, 16 May 2001
http://www.cnn.com/2001/TECH/space/05/16/space.mining/index.html
By Richard Stenger
CNN
(CNN) -- A handful of entrepreneurs have set their sights on some
heavenly
dividends, whether by strip mining the moon for energy,
extracting platinum
from asteroid mountains or distilling water from dormant comets.
In the past those hoping to transform the final frontier into
cosmic cash
have drawn mostly snickers. But in recent years such mavericks
have elicited
something else -- respect and funding from major industries and
governments
in the usually exclusive club of space exploration.
The assortment of scientists, investors and bureaucrats pushing
for mining
in space envision an incredibly wide range of ventures. Naturally
many would
like first to exploit the moon, the Earth's nearest celestial
neighbor.
[John S.] Lewis, a planetary scientist at the University of
Arizona, thinks
the moon could help Earth whet its voracious energy appetite. It
possesses
all the raw materials necessary to construct simple solar arrays.
"If we build them on the moon, we can extract all the
materials from the
lunar dirt. With a small factory on the moon, we could churn out
enormous
solar arrays from the materials," Lewis said.
"Most of the mass is simple stuff, just wires and beams,
nuts and bolts.
There's just no reason to launch this stuff from the space
shuttle. (The
expense) would kill a program dead."
Lewis derides the shuttle "as the most expensive way to put
a pound of cargo
into orbit devised by the human mind." Each pound costs
$10,000. Lewis and
others suggest private alternatives could do the job at a
fraction of the
cost.
Striking lunar pay dirt
But building this particular infrastructure on the moon would
avoid the cost
of an Earth launch altogether. By collecting solar rays on the
lunar surface
and beaming them to Earth receivers, it also would avoid the
environmental
consequences of burning fossil fuels.
Lewis acknowledges it would have staggering up-front costs, but
argues that
it could provide electricity cheaper than conventional means.
"We can at least meet or undercut price of energy in the
industrialized
world."
Others think they can coax energy from the moon another way.
Harrison
Schmitt, who walked on the moon in 1972, wants to mine an unusual
form of
helium from his former stomping grounds.
Helium 3, nearly absent on Earth but common on the moon, could
serve as
rocket fuel for deep space vessels, according to the former
Apollo
astronaut.
Others are not so sure. "I can't make the numbers work out
economically. You
would have to mine 100 million tons of lunar dirt for 1 ton of
helium 3,"
said Lewis, the target of skeptics himself for his solar space
ideas.
"I still can't make the case in my mind to collect energy in
space and beam
it back down on Earth. It would be better to collect it on the
ground," said
Jim [Benson], founder of SpaceDev, a California-based company
seeking to
turn a profit in space by any means necessary.
Space capitalists view each other like artists perusing the work
of their
peers. They share the same dreams, inspirations and tools of the
trade. But
each is convinced his vision is correct while all others are
blurry.
Jim Muncy, an aerospace consultant, considers the rivalry
healthy.
"We don't know how space is going to unfold as a
frontier," he said. "It's
good to have a competition of ideas, all contributing their
different ideas
of how we're getting into space."
Mother lodes dwarf U.S. GNP
The first places where humans could strike it rich in space are a
handful of
asteroids near Earth, composed almost completely of valuable
metals: iron,
nickel, gold, platinum.
In particular, the asteroid Amun, a mountain of natural stainless
steel
mixed with precious metals, contains 30 times as much metal as
humans have
mined and processed throughout history, Lewis said. The smallest
of dozens
of known metallic asteroids, it would be worth at least an
estimated $20
trillion based on current market prices.
"We should view this asteroid as a resource instead of a
threat," he said.
[Benson] does. He had originally hoped to send a probe this year
to check
mining prospects on a heavy metal asteroid. But finding investors
for this
specific journey has been a challenge, as has figuring a way to
bring back
the goods.
"How do you chip a piece of a one-mile mountain of steel? I
haven't solved
that one in my mind," [Benson] said.
Yet the former Internet mogul is upbeat. "The natural
resources in
near-Earth space are unimaginable. All these asteroids have
untold wealth
and they are easy to get to."
The smallest of dozens of known metallic asteroids, Amun would be
worth at
least an estimated $20 trillion based on current market
prices.
A prospecting mission to an asteroid would access the economic
value,
establish an ownership claim and cost under $50 million, [Benson]
said.
"Anyone who owns a mega-yacht or large jet can afford their
own planetary
deep space mission."
Such a mission has in fact already been undertaken. In February,
a NASA
probe settled onto the dusty surface of the asteroid Eros.
Although composed
mostly of rock, the 21-mile-long potato-shaped lump contains a
lode of
precious metal comparable to Amun.
Space mining enthusiasts concede that political and economic
realities
likely will delay the ambitions for decades. Yet most remain
optimistic.
"It's going to take a long time, but I'm not going to be a
skeptic. I think
it's going to happen sometime in the future," Muncy said.
Economics will necessitate it. Most of the Earth's valuable
metals remain
locked far below the surface in the unimaginably hot and dense
core.
Only a small fraction has bubbled close enough to the surface
through
volcanic cracks and fissures to be extracted through mining,
which will
deplete the available metals within an estimated three centuries.
In the meantime, prospective space miners contemplate other ways
to make
space pay. Some asteroids in our neighborhood are thought to be
dormant
comets, primordial icebergs coated with layers of rocky debris.
Elusive Holy Grail in space
Whoever can tap them would have at their fingertips the most
precious
substance in space travel.
"If we can get to the water inside, that's the secret to
opening space. And
that is my personal Holy Grail," [Benson] said.
A NASA probe landed in February on the asteroid Eros, a
potato-shaped rock
thought to contain trillions of dollars worth of
metals
Any serious ventures beyond Earth would require using resources
in space.
The cost of blasting them, including water, beyond the reach of
Earth's
gravity would make such trips economically unfeasible.
"When we get to Earth orbit, we are running out of gas. The
energy of
getting us to Earth orbit is roughly the same as getting us to
anywhere in
the solar system," [Benson] said.
Besides supporting human life, water in space could power
spacecraft. Split
water into hydrogen and oxygen and what does one have? The two
main
propellants that boost the space shuttle into orbit. If future
spacecraft
gas up after they leave Earth, they would save a fortune in
transportation
costs.
Some space entrepreneurs have changed their strategies in the
near future.
Bensen has placed emphasis on a lunar prospector mission rather
than an
asteroid one, which he predicts will launch within years.
Fearful of rivals, he declined to comment on what he would do
there. "That's
a competitive and proprietary area," he said.
[Benson] wants to keep ahead of the pack. SpaceDev has recently
inked deals
with aerospace giant Boeing and the U.S. government to
collaborate on
upcoming space missions.
Advancing the idea that space travel can take place cheaply,
SpaceDev won a
NASA contract to design and manage an orbiter that will measure
hot
interstellar plasma.
"We're a real company, building a real satellite. It's
NASA's cheapest ever
and we're building it next year," [Benson] beamed.
Not quite lining one's pockets with millions of tons of platinum.
But
[Benson] has not lost sight of his dream. He likens himself to a
sailor,
tacking his ship back and forth in the wind, but always heading
toward the
horizon.
"Our goal hasn't changed one iota. We just decided we must
take smaller
practical steps to reach it," he said.
Copyright 2001, CNN
=============
(2) ASTRONOMERS PUZZLED OVER COMET LINEAR'S MISSING PIECES
From Andrew Yee <ayee@nova.astro.utoronto.ca>
CONTACT:
Donna Weaver
Space Telescope Science Institute, Baltimore, MD 21218
(Phone: 410-338-4493, E-mail: dweaver@stsci.edu)
Hal Weaver
The Johns Hopkins University,6-4251, E-mail: weaver@pha.jhu.edu)
EMBARGOED UNTIL: 2:00 p.m. (EDT) Thursday, May 17, 2001
PRESS RELEASE NO.: STScI-PR01-14
ASTRONOMERS PUZZLED OVER COMET LINEAR'S MISSING PIECES
Astronomers analyzing debris from a comet that broke apart last
summer spied
pieces as small as smoke-sized particles and as large as
football-field-sized fragments. But it's the material they didn't
see that
has aroused their curiosity.
Tracking the doomed comet, named C/1999 S4 (LINEAR), NASA's
Hubble Space
Telescope's Wide Field and Planetary Camera 2 found tiny
particles that made
up the 62,000-mile-long (100,000-kilometer-long) dust tail and 16
large
fragments, some as wide as 330 feet (100 meters). Hubble detected
the small
particles in the dust tail because, together, they occupy a large
surface
area, which makes them stand out in reflected sunlight. However,
the
estimated mass of the observed debris doesn't match up to the
comet's bulk
before it cracked up.
"The mass of the original, intact nucleus is estimated to be
about 660
billion pounds (300 billion kilograms), according to some
ground-based
observers who were measuring its gas output," says Hal
Weaver, an astronomer
at the Johns Hopkins University in Baltimore, Md., who studied
the comet
with the Hubble telescope, the European Southern Observatory's
Very Large
Telescope (VLT) in Chile, and other ground-based telescopes.
"However, the total mass in the largest fragments measured
by the Hubble
telescope and the VLT is only about 6.6 billion pounds (3 billion
kilograms), and the dust tail has an even smaller mass of about
0.7 billion
pounds (0.3 billion kilograms). In other words, the total mass
measured
following the breakup is about 100 times less than the estimated
total mass
prior to the
breakup." Weaver's results will be published in a special
May 18 issue of
Science devoted to the transitory comet.
So where is the rest of the comet's fractured nucleus? Perhaps,
suggest
Weaver and other investigators, most of the comet's bulk after
the breakup
was contained in pieces between about 0.1 inches (2.5
millimeters) and 160
feet (50 meters) across. These pebble-sized to house-sized
fragments cannot
be seen by visible-light telescopes because they do not have
enough surface
area to make them stand out in reflected sunlight. Comets are
leftover
debris from the creation of the solar system 4.6 million years
ago. They're
made up of a combination of solid rock and frozen gases held
together by
gravity.
If the midsized cometary fragments exist, then the fundamental
building
blocks that comprised LINEAR's nucleus may be somewhat smaller
than what
current "rubble pile" theories of the solar system's
formation suggest.
These theories generally favor football-field-sized fragments,
like the ones
observed by the VLT and the Hubble telescope. The analysis of
LINEAR's
fragments indicates that the "rubble" comprising
cometary nuclei may be
somewhat smaller than previously thought.
Another puzzling question is why the comet broke apart between
June and July
of last year as it made its closest approach to the Sun.
"We still don't know what triggered the comet's
demise," Weaver says. "But
we do know that carbon monoxide (CO) ice probably did not
contribute to the
breakup."
Hubble's Space Telescope Imaging Spectrograph detected low levels
of this
volatile material, about 50 times less than was observed in
comets Hale-Bopp
and Hyakutake. Carbon monoxide ice sublimates [changes directly
from a solid
to a vapor] vigorously, even at the cold temperatures in a
comet's interior.
This activity could lead to a buildup of pressure within the core
that might
cause the nucleus to fragment.
"The scarcity of carbon monoxide in LINEAR's nucleus is
problematic for any
theory that attempts to invoke it as the trigger for the comet's
demise,"
Weaver says.
An armada of observatories, including the Hubble telescope,
watched the
dazzling end to the transitory comet. Hubble was the first
observatory to
witness LINEAR breaking apart, spying in early July a small piece
of the
nucleus flowing down the doomed comet's tail. LINEAR completely
disintegrated in late July as it made its closest approach to the
Sun, at a
cozy 71 million miles. Again, the Hubble telescope tracked the
comet,
finding at least 16 fragments that resembled
"mini-comets" with tails. Now
LINEAR is little more than a trail of debris orbiting the Sun.
The comet is
believed to have wandered into the inner solar system from its
home in the
Oort Cloud, a reservoir of space debris on the outskirts of the
solar
system.
"We were witnessing a rare view of a comet falling to
pieces," Weaver says.
"These observations are important because, by watching comet
LINEAR unravel,
we are essentially seeing its formation in reverse. The nucleus
was put
together 4.6 billion years ago when the Earth and other planets
were
forming, so by watching the breakup we are looking backwards in
time and
learning about conditions during the birth of the solar
system."
Weaver notes, however, that astronomers may have witnessed an
"oddball"
comet break apart.
"I've never seen anything like this," he says. "I
know of no other example
of a comet falling to pieces like this. Comet Shoemaker-Levy 9
fell apart,
but tidal forces from Jupiter caused that disintegration. LINEAR
didn't come
close to any other large object. Comet Tabur (C/1996 Q1) also
seemed to
vanish without a trace, but it already was the fragment of
another comet
nucleus [C/1988 A1 (Liller)]. Some investigators concluded that
Tabur did
not even break up but rather, became 'invisible' only because the
icy area
on its surface was no longer in sunlight, and its activity shut
down as a
result."
Comet LINEAR was named for the observatory that first spotted it,
the
Lincoln Near Earth Asteroid Research (LINEAR) program.
The Space Telescope Science Institute (STScI) is operated by the
Association
of Universities for Research in Astronomy, Inc. (AURA), for NASA,
under
contract with the Goddard Space Flight Center, Greenbelt,
MD. The Hubble
Space Telescope is a project of international cooperation between
NASA and
the European Space Agency (ESA).
There are no new Hubble pictures, but previously released Hubble
Space
Telescope images of Comet LINEAR's breakup are available on the
Web at:
http://oposite.stsci.edu/pubinfo/pr/2000/26/index.html
and
http://oposite.stsci.edu/pubinfo/pr/2000/27/index.html
========
(3) DYING COMET'S KIN MAY HAVE NOURISHED LIFE ON EARTH
From Mark Hess < mhess@pop100.gsfc.nasa.gov
>
William
Steigerwald
EMBARGOED FOR RELEASE
William.A.Steigerwald.1@gsfc.nasa.gov
May 17, 2001 at 2:00 p.m.
EDT
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-5017)
Release No. 01-46
DYING COMET'S KIN MAY HAVE NOURISHED LIFE ON EARTH
A comet that shattered on its approach to the Sun breathed new
life into the
theory that comet impacts provided most of the water in Earth's
oceans. The
same NASA observations of the comet, designated C/1999 S4 LINEAR
(LINEAR),
also support the idea that comet impacts furnished a significant
amount of
the organic molecules used in life that later arose on Earth.
LINEAR was the first comet with a chemistry that indicated its
water had the
same isotopic composition as the water actually found on Earth.
"The idea that comets seeded life on Earth with water and
essential
molecular building blocks is hotly debated, and for the first
time, we have
seen a comet with the right composition to do the job," said
Dr. Michael
Mumma of NASA's Goddard Space Flight Center in Greenbelt, Md.
Mumma is lead
author of a paper about this research to appear in the May 18
issue of
Science.
A separate announcement, also to appear in the May 18 Science, is
a unique
observation that reveals just how much water comets of this type
can carry.
LINEAR, with a nucleus estimated at 2,500 to 3,300 feet (about
750 to 1,000
meters) in diameter, carried about 3.6 million tons (3.3 billion
kilograms)
of water within its bulk, according to astronomers who used the
Solar Wind
Anisotropies instrument on the Solar and Heliospheric Observatory
spacecraft
to observe water vapor released from the comet as it fragmented.
Using telescopes sensitive to infrared light, Mumma and a team of
astronomers studied comet LINEAR before its dramatic breakup last
July and
determined that its unusual chemistry points to an origin near
Jupiter's
orbit. Comets that formed in this region are expected to have the
same ratio
of normal water to "heavy" water as found in Earth's
oceans.
Although it would appear that all water molecules are identical
-- two atoms
of hydrogen joined to one oxygen atom -- this isn't the case.
Hydrogen comes
in different types (isotopes) that behave the same way chemically
but are
heavier due to an extra component (one or more neutrons) in their
nuclei.
One such heavy cousin of hydrogen is called deuterium (one extra
neutron).
Based on very low-temperature experiments of gas chemical
reactions, water
ice incorporated in comets that formed far from the Sun (near
Neptune's
orbit, for example) should have a greater deuterium to hydrogen
(D to H)
ratio than the water found on Earth.
Recent observations of comets Halley, Hyakutake, and Hale-Bopp
confirm this,
leading researchers to believe that these comets formed further
from the Sun
than LINEAR. Pinpointing the origin of these comets was
remarkable, but it
provided no support for the cometary origin of water on Earth.
The chemistry of LINEAR, however, indicated that it formed in
warmer regions
closer to the Sun. For example, it had much less carbon monoxide
(CO),
methane (CH4), ethane (C2H6), and acetylene (C2H2) than typical
remote-origin comets like Halley. These volatile organic
molecules freeze at
extremely cold temperatures, so it appears that LINEAR formed in
a place
where it was too warm to incorporate a great deal of these
volatile
molecules into its ices.
However, the same low-temperature experiments that successfully
predicted
the correct D to H ratio in remote-origin comets predict that a
comet
forming in a warmer Jupiter orbit region should have the same D
to H ratio
as Earth's water. LINEAR broke up before this could be confirmed,
but its
low amount of volatile organic molecules provides a strong
indication that
it carried the same kind of water that comprises terrestrial
seas.
LINEAR is believed to have arrived from the Oort cloud, a vast
comet swarm
surrounding the frigid distant regions of the solar system,
trillions of
miles from the Sun. According to theories of the solar system's
formation,
these comets formed from the same gas and dust cloud that gave
rise to the
planets and the Sun. They accumulated in the colder regions where
the gas
giant planets are found today (Jupiter - Neptune). Gravity from
the gas
giants kicked the comets out of the solar system, either to
interstellar
space or to the Oort cloud region. Occasionally, the Oort cloud
is
perturbed, perhaps by the gravity of a passing star, returning
some comets
to the inner solar system. The amount of various molecules
incorporated into
a comet's ices depends on temperature, so determining a comet's
chemistry
reveals where in the gas giant region the comet formed.
As the most massive planet in the solar system, Jupiter's gravity
was so
powerful that it shoved most comets near it into interstellar
space, while
the lesser gravity from the smaller gas giants gave comets near
them a
gentler push, landing a greater portion in the Oort cloud.
Consequently, comets that formed near Jupiter are rare today, but
they would
have been in the majority during the solar system's formation,
simply
because the Jupiter orbit region had most of the material in the
pre-planetary gas and dust cloud. Therefore, scientists expect
that the
primordial Earth would have intercepted more comets formed near
Jupiter's
region than those formed elsewhere.
Because Jupiter's region was closer to the Sun than the other gas
giant
planets, it received more light and was warmer, so more reactions
occurred
in the gas. Thus, greater amounts of complex organic molecules
were
available to wind up in a comet. Also, Jupiter's powerful gravity
kept
collision speeds between comets near it high, preventing them
from growing
very large. Both factors may have given a boost to life on Earth.
"It's like being hit by a snowball instead of an
iceberg," said Mumma. "The
smaller comets from Jupiter's region impacted Earth relatively
gently,
shattering high in the atmosphere and delivering most of their
organic
molecules intact. Also, these comets would have had a greater
portion of
life's building blocks -- the complex organic molecules -- to
begin with.
This means life on Earth did not have to start completely from
scratch.
Instead, it was delivered in kit form from space."
The team used infrared-sensitive instruments on telescopes at the
W. M. Keck
Observatory and the NASA Infrared Telescope Facility, both on
Mauna Kea,
Hawaii, to make the observations. Heat and light from the Sun
caused
material from LINEAR to evaporate into space and form a gas cloud
around the
comet as it entered the solar system. Sunlight energized
molecules in the
gas cloud surrounding LINEAR, allowing the team to identify the
comet's
chemistry by the unique types of infrared light emitted by its
various
molecular components. Comet LINEAR was named for the observatory
that first
spotted it, the Lincoln Near Earth Asteroid Research (LINEAR)
program.
For more information and pictures, refer to:
http://www.gsfc.nasa.gov/GSFC/SpaceSci/origins/linearwater/linearwater.htm
==========
(4) BREAKING UP IS HARD TO DO, EVEN FOR A COMET
From Ron Baalke <baalke@jpl.nasa.gov>
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Martha J. Heil (818) 354-0850
FOR IMMEDIATE
RELEASE
May 17, 2001
BREAKING UP IS HARD TO DO, EVEN FOR A COMET
Scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
helped to
piece together what happened when Comet LINEAR (C/1999 S4)
disintegrated in
July 2000, and their results will appear today in a special issue
of Science
featuring studies of the comet.
Scientists watched the comet break up when it was nearly 115
million
kilometers (72 million miles) from the Sun. NASA's Hubble Space
Telescope
and the Very Large Telescope took pictures at different
resolutions and
different times. From the pictures, scientists learned the
details of how
the comet broke up. The team was led by Dr. Hal Weaver, an
astronomer at the
Johns Hopkins University in Baltimore, Md. The fragments have
spread out, to
disappear forever into deep space. The mini-comets that the
scientists saw
ranged from about some 50 to more than 100 meters (165 to more
than 300
feet) across. Today, the pieces will be roughly 600 million
kilometers (400
million miles) from Earth.
"One question we tried to answer was, 'Did everything happen
at one time, or
did the pieces of the comet slowly fragment off?'" said Dr.
Zdenek Sekanina
of JPL, the paper's second author. He identified some of the
fragments in
the pictures from Hubble and the Very Large Telescope, determined
their
sizes and relative motions and the times they separated. "We
found that the
comet's breakup was gradual but episodic. Also, the distances
among the
mini-comets grew as time went by, and we wanted to find out how
rapidly."
There are two forces working on the different distances between
the
mini-comets, Sekanina said. One is that the fragments broke off
at different
times. The other is that gases flowing from the broken chunks of
dust and
ice were propelling them to different speeds depending on their
size.
Sekanina predicted that the tail would become a narrow, bright
band, made
from the sunlight-reflecting dust released as the comet crumbled.
While the
new tail was relatively bright at first, the comet's original
head
disappeared, confusing calculations of the orbit. The last
pictures of the
tail were taken in the second half of August 2000, about four
weeks after
the event. Then the comet's remains vanished forever.
Dr. Michael Keesey of JPL calculated the comet's orbit, its
distance from
the Sun, its probable origin and its angle to Earth. It was a
long period
comet, born in the Oort cloud, which is postulated to extend from
outside
the orbit of the farthest planet, Pluto, to about 30 trillion
kilometers (20
trillion miles) from the Sun. It took comet LINEAR about 60,000
years to
travel once around the Sun.
The comet, popularly called LINEAR for the site of its discovery,
the
Lincoln Near Earth Asteroid Research, Lexington, Mass., was one
of several
dozen comets discovered in this way.
Another comet discovered by LINEAR, C/2001 A2, recently broke up
as it was
nearing the Sun. It was observed to undergo an outburst in late
March 2001,
which may have signalled the splitting. Breaking up may be a
common end for
comets, Keesey said.
JPL is managed by the California Institute of Technology in
Pasadena for
NASA. A picture of the comet is available at
http://www.jpl.nasa.gov/pictures/comet
.
============
(5) SOHO'S UNIQUE VIEW OF A COMET THAT FELL TO PIECES
From ESA Science News
http://sci.esa.int
18 May 2001
SOHO's unique view of a comet that fell to pieces
When Spain's Instituto de Astrofisica de Canarias reported on 28
July 2000
that an ordinary-looking comet was breaking up, some of the
world's top
telescopes watched its subsequent disintegration till nothing was
left. The
French-Finnish SWAN instrument on the SOHO spacecraft had already
been
observing Comet LINEAR by ultraviolet light for two months, and
continued to
watch it till the remnants faded from view in mid-August. Today
the SWAN
team reports, in the journal Science, that their observations
showed four
major outbursts in June and July.
The fragmentation seen by SWAN began on 21 July, almost a week
before
observers on the ground noticed it. Between 25 May and 12 August,
the dying
comet released altogether 3.3 million tonnes of water vapour into
space, as
its ice evaporated in the warmth of the Sun. The data also
suggest that the
density of Comet LINEAR was extremely low.
"Only SWAN on SOHO saw the entire drama of this
self-destroying object,"
comments Teemu Mäkinen of the Finnish Meteorological Institute,
lead author
of the report in Science. "The ice on the surface of the
comet's nucleus did
not simply vaporize as in a normal comet, but came away in large
chunks. We
saw 90 per cent of the ice falling off before the complete
fragmentation of
the remainder began."
Comet LINEAR, known more formally as Comet 1999 S4, was
discovered by the
LINEAR asteroid-hunting telescope in the USA, and may have been
making its
first visit to the Sun. It disappointed amateur astronomers by
not becoming
bright enough to see with the naked eye. The break-up occurred
near the time
of the comet's closest approach to the Sun on 26 July, when it
was moving
across the sky from Ursa Major towards Leo.
In early August the NASA-ESA Hubble Space Telescope and the
European
Southern Observatory's Very Large Telescope in Chile both saw
about 16
fragments in the form of mini-comets, which faded away by the
middle of the
month. These observations by visible light indicated that the
pieces were
about 100 metres in diameter. A prominent dust tail still visible
in early
August corresponded with the onset of fragmentation seen by SWAN
on 21 July.
SWAN's unique capability in observing comets comes from its
continuous
scanning of the whole sky, at just the right ultraviolet
wavelength to see
the cloud of hydrogen atoms that surrounds every moderately
active comet.
The hydrogen comes from the break-up of water molecules released
from the
comet by the Sun's warmth. SWAN also benefits from its location
on the
ESA-NASA SOHO spacecraft 1.5 million kilometres from the Earth,
well clear
of a hydrogen cloud that surrounds the Earth itself.
"Our primary aim is to study the interaction of the solar
wind with
interstellar hydrogen," explains Jean-Loup Bertaux of
France's Service
d'Aéronomie, the principal investigator for SWAN. "But we
always knew that
we'd have an excellent view of comets too. They are quite often
traceable in
our records even before their formal discovery by others."
Lessons from the SWAN song of Comet LINEAR
Complete fragmentation provides a rare opportunity for scientists
to learn
about the internal make-up of a comet. Members of the SWAN team
believe that
their newly published results compel them and their fellow
scientists to
think afresh about Comet LINEAR's construction, and to consider
that
different parts of the young Solar System may have produced
comets of
different sorts.
"Comets do not usually blow themselves to smithereens,"
says lead author
Mäkinen. "So we should not be surprised if Comet LINEAR was
peculiar in
composition and structure compared with other comets."
The character of the comet did not change throughout the months
of
observation by SWAN, even when deep layers inside the nucleus
were being
laid bare. Comet scientists usually have to consider the
possibility that
the surface of the nucleus is different in composition from the
interior.
One lesson from the 'SWAN song' of Comet LINEAR seems to be that,
in this
case at least, the surface exposed at the outset was
representative of the
whole nucleus.
The SWAN team also suspects that Comet LINEAR was as flimsy and
light as the
expanded polystyrene used for packing fragile equipment. The
density of its
water ice may have been as low as 15 kilograms per cubic meter,
compared
with 917 kg/m3 for familiar non-porous ice on the Earth. Even
allowing for a
possibly equal mass of dust grains within the comet, a total
density of 30
kg/m3 would be far less than the 500 kg/m3 often assumed by comet
scientists. By this reckoning, the initial diameter of Comet
LINEAR on its
approach to the Sun was about 750 metres.
"Our opinion about the low density is tentative and
controversial," says
Jean-Loup Bertaux. "We expect plenty of arguments with our
colleagues when
we put all the observations of Comet LINEAR together. But we
start with the
advantage of having seen the whole course of events, which no
one else did."
The break-up of Comet LINEAR gave a small-scale impression of the
disintegration, many centuries ago, of a far larger comet into an
enormous
swarm of mini-comets. LASCO, another instrument on SOHO, has
observed
hundreds of the fragments from that event falling into the Sun.
For more information please contact:
Dr. Paal Brekke, ESA-SOHO Deputy Project Scientist
Tel: +1 301 286 6983 / +1 301 996 9028
Fax: +1 301 286 0264
Email:pbrekke@esa.nascom.nasa.gov
Dr. Teemu Mäkinen, SWAN scientist, Finnish Meteorological
Institute
Tel: +358-9-1929-4647
Fax: +358-9-1929-4603
Email:teemu.makinen@fmi.fi
Dr. Jean-Loup Bertaux, Service d'Aeronomie du CNRS
Tel : 33-(0)1-64 47 42 51
Fax : 33-(0)1-69 20 29 99
Email:bertaux@aerov.jussieu.fr
USEFUL LINKS FOR THIS STORY
* SWAN home page (Finnish Meteorological Institute)
http://www.fmi.fi/research_space/space_7.html
* SWAN home page (Service d'Aeronomie, France)
http://www.aero.jussieu.fr/~jgoutail/
* SOHO home page (at the ESA Science web site)
http://sci.esa.int/soho/
* SOHO mission
http://sohowww.estec.esa.nl/
* SOHO's comet discoveries
http://sci.esa.int/content/news/index.cfm?aid=14&cid=2097&oid=12363
* SOHO analyses a kamikaze comet
http://sci.esa.int/content/news/index.cfm?aid=14&cid=2097&oid=26188
* SOHO sees two comets plunge into Sun
http://sci.esa.int/content/news/index.cfm?aid=14&cid=2097&oid=12206
IMAGE CAPTIONS:
[Image 1:
http://sci.esa.int/content/searchimage/searchresult.cfm?aid=1&cid=1&oid=27088&ooid=27113
]
The hydrogen cloud around Comet LINEAR as observed by the SWAN
instrument on
SOHO on 26 June 2000, almost a month before the comet
disintegrated. The
field of view is 21 million kilometres wide. Credit: SOHO/SWAN
(ESA & NASA)
& J.T.T. Mäkinen et al.
[Image 2:
http://sci.esa.int/content/searchimage/searchresult.cfm?aid=1&cid=1&oid=27088&ooid=27114
]
Fragments of Comet LINEAR seen as mini-comets by the Hubble Space
Telescope
on 5 August 2000. Part of a dust tail is visible at top right.
Credit:
HST/WFPC2 (NASA & ESA) & H.A. Weaver et al.
==========
(6) CHANGES IN SUN'S INTENSITY TIED TO RECURRENT DROUGHTS IN MAYA
REGION
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News & Public Affairs
University of Florida
Contact Information:
Mark Brenner, (352) 392-2231, brenner@ufl.edu
Writer: Aaron Hoover, ahoover@ufl.edu
Sources: David Hodell, (352) 219-8873, dhodell@geology.ufl.edu
May 17, 2001
CHANGES IN SUN'S INTENSITY TIED TO RECURRENT DROUGHTS IN MAYA
REGION
GAINESVILLE, Fla. -- The Maya were talented astronomers,
religiously intense
in their observations of the sun, moon and planets. Now, new
research shows
something in the heavens may have influenced their culture and
ultimately
helped bring about their demise.
In an article set to appear in Friday's issue of the journal
Science, a team
of researchers led by a University of Florida geologist reports
finding that
the Yucatan Peninsula, seat of the ancient Maya civilization, was
buffeted
by recurrent droughts. More importantly, the research shows, the
droughts --
one of which is thought to have contributed to the collapse of
the Maya
civilization -- appear to have been caused by a cyclical
brightening of the
sun.
"It looks like changes in the sun's energy output are having
a direct effect
on the climate of the Yucatan and causing the recurrence of
drought, which
is in turn influencing the Maya evolution," said David
Hodell, a UF
professor of geology and the paper's lead author.
In 1995, Hodell and two colleagues at UF published results in the
journal
Nature suggesting that the ninth-century collapse of the Maya
civilization
may have been influenced by a severe drought that lasted for more
than 150
years. The paper, co-authored by Mark Brenner, a UF assistant
professor of
geology and director of UF's Land Use and Environmental Change
Institute,
and Jason Curtis, a UF geology researcher, was based on analysis
of a
sediment "core" from Lake Chichancanab on the north
central Yucatan
Peninsula in Mexico.
Cores are samples of lake sediment retrieved by driving a hollow
tube into
the lake bottom. The sediments are deposited layer by layer, like
a wedding
cake, with the oldest layer at the bottom. Such cores provide a
timeline
that allows researchers to obtain a continuous record of changes
in climate,
vegetation and land use.
For the latest research, Hodell, Brenner and Curtis returned to
the lake and
collected a new series of cores. The researchers discovered
layers of
calcium sulfate, or gypsum, concentrated at certain levels in the
cores.
Lake Chichancanab's water is nearly saturated with gypsum. During
dry
periods, lake water evaporates and the gypsum falls to the lake
bottom. The
layers therefore represent drought episodes. The researchers
found the
recurrence of the deposits is remarkably cyclical, occurring
every 208
years, although they varied in intensity.
The 208-year cycle caught the researchers' attention because it
is nearly
identical to a known 206-year cycle in solar intensity, Hodell
said. As part
of that cycle, the sun is most intense every 206 years, something
that can
be tracked through measuring the production of certain
radioactive
substances such as carbon-14. The researchers found the drought
episodes
occurred during the most intense part of the sun's cycle.
Not only that, the researchers found the droughts occurred at
times when
archeological evidence reflects downturns in the Maya culture,
including the
900 A.D. collapse. Such evidence includes abandonment of cities
or slowing
of building and carving activity.
As Hodell said, the energy received by the Earth at the peak of
the solar
cycle increases less than one-tenth of 1 percent, so it's likely
that some
mechanism in the climate is amplifying the impact in the Yucatan.
Archaeologists know the Maya were capable of precisely measuring
the
movements of the sun, moon and planets, including Venus. Hodell
said he is
unaware, however, of any evidence the Maya knew about the
bicentenary cycle
that ultimately may have played a role in their downfall.
"It's ironic that
a culture so obsessed with keeping track of celestial movements
may have met
their demise because of a 206-year cycle," he said.
The cycle continues to the present, which happens to fall into
about the
middle of the 206-year period, Hodell said. Even a severe drought
today,
however, isn't likely to have the same impact on the culture as
in ancient
times. Brenner noted North Korea currently is suffering an
extreme drought,
but the country has the benefit of international aid.
"Nobody stepped in to help the Maya out," he said,
"and as conditions
worsened, it probably created a lot of stress among various Maya
cities
competing for resources."
Thomas Guilderson, of the Lawrence Livermore National Laboratory,
assisted
the UF scientists in the research, which was funded by the
National Science
Foundation Paleoclimate Program. The cores were collected for a
BBC program
on climate and Maya culture collapse.
===========
(7) SAVE THE EARTH: DELAYING OUR PLANET'S ULTIMATE DEMISE-BY
SHIFTING ITS
ORBIT
From Scientific American, 16 May 2001
http://www.sciam.com/2001/0601issue/0601scicit6.html
Sending a giant rock toward Earth every 6,000 years has its
dangers:
Collision - The asteroid could hit Earth, rather than flying by
it.
Orbital destabilization - The change in Earth's orbit could
disturb the
motions of the other planets.
Loss of the moon - Most likely, the moon would be stripped away
from Earth
unless some additional energy-expensive shepherding were
arranged. The moon
helps to stabilize Earth's axial tilt, and its absence could
radically upset
our planet's climate.
One billion years-that's about all the time we have until the
increasing
luminosity of the aging sun cooks our planet to near death. But
it does not
have to be this way. Researchers argue that gradually moving
Earth farther
from the sun is possible.
Since the sun formed 4.6 billion years ago, it has steadily grown
and gotten
brighter. Already it shines about 30 to 40 percent brighter than
it did when
it first entered the main sequence, its current long-lived period
of
stability. In about one billion years the sun will be 10 percent
more
luminous than it is now-more than adequate to make land-based
life difficult
or even impossible. A team led by Donald G. Korycansky of the
University of
California at Santa Cruz has developed an ambitious yet feasible
plan that
could add another six billion years to our planet's sell-by date.
The
process is an unusual application of the well-known gravitational
slingshot.
As a spacecraft closes in on a planet, gravity accelerates the
probe, and it
shoots away with added energy. That extra energy does not come
free, though:
the planet suffers equal and opposite changes in energy and
momentum.
In the same way, the team's paper, published in the March
Astrophysics and
Space Science, shows how Earth's orbit can be increased very
slightly if a
suitable asteroid (or any object about 100 kilometers across and
weighing
about 1016 metric tons) can be made to fly in front of Earth as
it moves in
its orbit. In doing so, the asteroid imparts some of its orbital
energy to
Earth, shifting it to a slightly larger orbit. The orbit of the
asteroid is
engineered such that, after its flyby of Earth, it heads toward
Jupiter or
Saturn, where in the reverse process it picks up the orbital
energy it lost
to Earth. Then, when the asteroid reaches its farthest distance
from the
sun, a slight course correction is applied-by, say, firing
engines on the
asteroid using fuel manufactured from materials mined
there-sending it once
more toward Earth.
Korycansky and his collaborators calculate that for Earth to
enjoy the same
intensity of sunlight it does now, our planet would have to be
nudged
outward about once every 6,000 years, on the average, for the
entire
remaining main-sequence lifetime of the sun. In 6.2 billion years
Earth
would be just beyond the current orbit of Mars. The scenario
sounds like
science fiction, but it actually uses technology that is mere
decades away
from being reality.
Ambitious though the scheme is, it is no solution when the sun
encounters
its fate-as a cool, dim white dwarf. At the very end, escaping to
another
star system is ultimately the only option.
--by MARK A. GARLICK
Copyright 2001, Scientific American
============================
* LETTERS TO THE MODERATOR *
============================
(8) PYRAMIDS, FLIGHT ORIENTATED METEORITES AND BA NE-PE.
From Matthew Genge <M.Genge@nhm.ac.uk>
The suggestion by Toby Wilkinson (reported by Tim Radford,
Guardian, May
14th; CCNET 17th May) that the shape of a meteorite, perhaps the
Benben
stone of Heliopolis, may have provided the blueprint for the
pyramids is a
tantalising suggestion. The fact that the Benben stone was
conical or
pyramid in shape and that the capstone of a pyramid was known as
the
benbenet certainly adds substance to the argument. However, did
the
Egyptians really design the enormous funeral monuments of their
god Pharaohs
because they believed that stars, like the Benben stone, were
pyramidal?
Conical or pyramidal shaped meteorites form by flight orientation
during
atmospheric entry and typically are ordinary chondrite meteorites
(stony
meteorites). Removal of material by ablation from the front face
of the
meteoroid by ablation produces a roughly conical aspect with some
deposition of melt droplets occuring on the posterior face of the
body due
to rarefaction in the meteoroid trail. Importantly flight
orientated stones
are rare (<<0.1% of falls) and are thought to represent
single, relatively
small stones that have survived atmospheric entry without
fragmentation.
Much more commonly stony meteorites fragment, when the ram
pressure ahead of
the meteoroid exceeds their material strength, and fall as a
shower of
irregular shaped stones.
If flight orientated stones occur only rarely and are associated
with less
impressive fireball events without tremendous terminal
detonations (because
they are usually smaller stones) then it seems strange that the
Egyptians
would conclude that the stars are pyramid shaped when most
meteorites are
demonstrably not. It could have been, of course, that the fall of
the Benben
stone just happened to be the best witnessed meteorite fall or
that the fall
might have had some special significance. However, there is
evidence that
the Egyptians were familiar with meteorites and accepted their
heavenly
origins. Iron meteorites have been recovered from predynastic
graves (ca
3500 BC) at Gerzeh, as worked blades from the Tomb of Tutankhamun
(ca 1350
BC) and reputedly within a necklace belonging to an Egyptian
princess.
Indeed the old Egyptian word "ba ne-pe" means
"iron of heaven". If the
ancient Egyptians did consider flight orientated stones as
testimony to the shapes of the stars then presumably then they
must also
have made the intellectual leap that showers of irregular stones
resulted
from fragmentation.
If indeed the pyramids are inspired by the shape of flight
orientated stones
then I can imagine the sigh of relief given by the architect when
he was
first shown the meteorite by the Pharaoh's priests. By luck they
just
happened to choose about the only shape you could build a 145
metre high
monument, weighing 6 million tonnes, from relatively soft rock
without it
falling down. Presumably a few thousand years later a Mayan
architect must
have had a similar last minute reprieve.
Matthew Genge
The Natural History Museum
M.Genge@nhm.ac.uk
===========
(9) RE: EJECTED DINOSAUR RELICS
From S. Fred Singer <singer@sepp.org>
Dear Benny
Just a footnote to the entertaining letter from Andrew Glikson
(CCNet
17-05-01):
Escape velocity from the Earth gravity field is ~ 11km/sec.
Initial velocity
leaving the surface must be considerably higher, just to overcome
atmospheric friction. Therefore, the acceleration required
implies forces
that exceed the crushing strength of rocks by about an order of
magnitude. And if that were not enough, aerodynamic friction
should vaporize
most materials.
Best wishes
Fred
=============
(9) AND FINALLY, NO END TO END-TIME PROPHECIES: "MUTANT
BACTERIA BIOWARS
THREATEN APOCALYPSE NOW"
From SMH.com, 17 May 2001
http://www.smh.com.au/news/0105/17/world/world3.html
Genetic engineers already have it within their grasp to devise a
lethal
bio-weapon for terrorists and rogue states, the British science
publication
Nature warns this week.
Small changes in the DNA of well-known bacteria and viruses could
turn these
agents into mass killers, the journal says.
The publication echoes warnings by a pair of Australian
scientists, Dr Ron
Jackson and Dr Ian Ramshaw, who accidentally created an
astonishingly
virulent strain of mousepox, a cousin of smallpox, among
laboratory mice.
They realised that if similar genetic manipulation was carried
out on
smallpox, an unstoppable killer could be unleashed. They decided
to publish
their findings in January to draw attention to the potential
misuse of
biotechnology.
Nature warns: "Making subtle genetic alterations to existing
pathogens to
increase their virulence or durability in the environment, or to
make them
harder to detect or to treat with drugs, is within the limits of
today's
technology.
"With the decoding of a pathogen's entire genome now
commonplace, and
transgenic techniques advancing all the time, some researchers
believe that
the sinister potential of biology can no longer be ignored."
Biowarfare - use of germs or viruses such as anthrax or smallpox
- has long
been considered by military strategists. However, the risk has
increased
thanks to advances in knowledge about how genes work, new
techniques for
moving pieces of DNA around, and the relative ease with which a
rogue
organisation could build or hire a lab to build such a weapon.
Scientists interviewed by Nature ruled out, for the time being,
the ability
to build new, artificial agents from a set of component parts.
A far simpler way would be to tweak the performance of an
existing bacteria
to make it more resistant to antibiotics, they said.
The genetic sequences of bacteria such as tuberculosis, cholera,
leprosy and
the plague are already in the public domain - as is that of a
food poisoning
bug, Staphylococcus aureus, that is already becoming resistant to
antibiotics.
By identifying the genes from Staphylococcus aureus that make the
bug
resistant, and inserting them into the other bacteria, a
scientist could
make a killer for which there would be scant defence.
Dr Willem Stemmer, chief scientist with Maxygen, a California
pharmaceutical
research firm, used one of these techniques to explore how
resistance genes
work, Nature reports.
He created a strain of the common intestinal bug Escherichia coli
that was
32,000 times more resistant to the antibiotic cefotaxime than
conventional
strains. He destroyed the superbug in response to the American
Society for
Microbiology's concerns about potential misuse.
"It's time for biologists to begin asking what means we have
to keep the
technology from being used in subverted ways," said Harvard
University
molecular biologist Professor Matthew Meselson, who has often
spoken of the
dangers of biowarfare.
Agence France-Presse
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