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
--Mark Hess, Goddard Space Flight Center, 17 May 2001

    Larry Klaes <>

    Andrew Yee <>

    Mark Hess <>
    Ron Baalke <>

    ESA Science News, 18 May 2001

    Andrew Yee <>

    Matthew Genge <>

    S. Fred Singer <>



From Larry Klaes <>

CNN, 16 May 2001
By Richard Stenger

(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

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

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

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

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

"Our goal hasn't changed one iota. We just decided we must take smaller
practical steps to reach it," he said.

Copyright 2001, CNN


From Andrew Yee <>

Donna Weaver
Space Telescope Science Institute, Baltimore, MD 21218
(Phone: 410-338-4493, E-mail:

Hal Weaver
The Johns Hopkins University,6-4251, E-mail:

EMBARGOED UNTIL:  2:00 p.m. (EDT) Thursday, May 17, 2001



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

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

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

"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

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:


From Mark Hess  < >
William Steigerwald                   EMBARGOED FOR RELEASE           May 17, 2001 at 2:00 p.m.

Goddard Space Flight Center, Greenbelt, Md.

(Phone: 301/286-5017)

Release No. 01-46


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

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:


From Ron Baalke <>

PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011

Contact: Martha J. Heil (818) 354-0850

FOR IMMEDIATE RELEASE                              May 17, 2001


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 .


From ESA Science News

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

Dr. Teemu Mäkinen, SWAN scientist, Finnish Meteorological Institute
Tel: +358-9-1929-4647
Fax: +358-9-1929-4603

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


* SWAN home page (Finnish Meteorological Institute)
* SWAN home page (Service d'Aeronomie, France)
* SOHO home page (at the ESA Science web site)
* SOHO mission
* SOHO's comet discoveries
* SOHO analyses a kamikaze comet
* SOHO sees two comets plunge into Sun


[Image 1: ]
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: ]
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.


From Andrew Yee <>

News & Public Affairs
University of Florida

Contact Information:
Mark Brenner, (352) 392-2231,

Writer: Aaron Hoover,

Sources: David Hodell, (352) 219-8873,

May 17, 2001


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

"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.


From Scientific American, 16 May 2001

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.


Copyright 2001, Scientific American



From Matthew Genge <>

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


From S. Fred Singer <>

Dear Benny

Just a footnote to the entertaining letter from Andrew Glikson (CCNet

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



From, 17 May 2001

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

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

"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

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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