CCNet, 15 November 1999


     "The proxies indicate that a drier climate prevailed in the
     Shiyang River drainage during the last glacial. Lake Yiema was
     dry and eolian sand covered most part of the lake basin. During
     the early and middle Holocene, a moister climate prevailed in
     the drainage. Climate became dry stepwise with an abrupt
     transition from one stage to another during the entire Holocene
     and became driest since about 4,200 BP. Maximum dry climate
     spells occurred at about 12,000-10,000 BP and after about 4,200
        -- F.H. Chen et al. (1999) Environmental changes documented
           by sedimentation of Lake Yiema in arid China since the
           Late Glaciation

     SpaceViews, 14 November 1999

    Rainer Arlt <>

    Ron Baalke <>

    Explorezone, 11 November 1999

    Ron Baalke <>

    Jim Richardson <>

    Andrew Yee <>

    F.H. Chen et al., LANZHOU UNIVERSITY

    A.S. Gaur & K.H. Vora, MARINE ARCHAEOL CTR

     Andrew Yee <>

     H.H. von Muldau, PFIAT RES,ROSSDORF


From SpaceViews, 14 November 1999

A new meteor shower predicted by some astronomers to be visible last
week as a warmup to this week's Leonids failed to materialize, with
only a few meteors noticed by observers.

The "surprise" shower, informally dubbed the Linearids, was predicted
to be visible around November 11 when the Earth passed very near the
orbital path of newly-discovered long-period comet C/1999 J3 LINEAR,
just 40 days after the comet was in the same area.

This orbital coincidence led some astronomers to predict the
possibility of a meteor shower, as dust left behind by the comet in
its orbital path burned up in the Earth's atmosphere. This would be
visible on Earth as a shower of meteors appearing to radiate from
the bowl of the Big Dipper in the constellation Ursa Major.

Reports disseminated through the Internet in the days after the
predicted peak of the Linearids, though, showed no signs of any shower
observed by astronomers. Most only reported one or a few meteors coming
from Ursa Major per hour.

This was not a surprise for some astronomers. Existing meteor showers,
such as the Leonids, are associated with short-period comets, rather
than the 63,000-year period C/1999 J3 LINEAR. Short-period comets can
build up streams of dust throughout their entire orbital paths, so that
the showers can be seen on an annual basis.

Some astronomers planned to use their observations of the Linearids as
a warmup for the Leonids, an established annual meteor shower expected
to peak on the night of November 17-18.

Interest in the Leonids has been high because of the intense storms of
meteors seen approximately every 33 years, most recently in 1966.
Predictions for an intense storm last year fell through, with peak
sustained counts of 340 meteors an hour, far less than the 1996 peak of
40 meteors per second.

Predictions for 1999 by astronomers Rob McNaught and David Asher call
for a slightly greater peak rate of 500 meteors an hour, with that peak
likely to be best visible in the early morning hours November 18 in

The possibility of a meteor storm had caused concerns among spacecraft
operators last year, who feared damage to their spacecraft by the small
but high-speed meteors. In many cases they took steps to protect their
spacecraft by orienting them to protect vulnerable areas, such as solar
panels and electronics, and no damage to any satellites were reported.

With no major storm forecast for 1999, and with the experience of 1998,
operators are expected to take similar measures to protect their
spacecraft, but with considerably less fanfare.

While no major storm is predicted for 1999, and forecasts for 2000 call
for only a minor shower, astronomers should keep an eye out for 2001
and 2002. The forecasts by McNaught and Asher predict up to 15,000
meteors per hour in 2001 and 25,000 per hour in 2002 as the Earth
passes through newer, denser regions of the dust trail in the orbital
path of comet Tempel-Tuttle.

With no reports of major showers from the "Linearids", astronomers now 
turn their attention to this week's Leonids.

Copyright 1999, SpaceViews


From Rainer Arlt <>

       I M O   S h o w e r   C i r c u l a r

    Possible Activity from Comet C/1999 J3 LINEAR

A slight chance of meteor shower activity caused by debris from Comet 
C/1999 J3 (LINEAR) encouraged quite a few observers to check for
meteors from a radiant position near alpha=175deg, delta=+53deg as
predicted from the orbit of the Comet.

No activity outburst occurred. The below list of individual ZHR values
indicates weak activity all day on November 9, 1999, and in the evening
hours of November 11 near the passage of the node of the comet's orbit.
On several occasions the radiant elevation  was too low for a sensible
ZHR value. Due to possible contamination by sporadic background 
activity, the activity cannot be reliably associated with particles
from the Comet.

Radar records from Ondrejov, Czech Republic, indicate enhanced activity
between 21h and at least 3h UT on November 11/12 comared  with the day
before (see The
activity is associated with faint meteors, possibly beyond the visual
range. No clear enhancement appears in the forward scatter data by
Kazuhiro Sizuki (see

Date    Period UT   LM LIN nonLIN hR ZHR  Observer
Nov 08  1335-1415  6.0   2    3    4   -  Qi Rui (China)
Nov 08  1441-1528  6.0   0    6        0  Qi Rui (China)
Nov 08  1620-1750  6.0   3   15   18   9  Qi Rui (China)
Nov 08  1830-2027  6.0   0   14        0  Qi Rui (China)
Nov 09  0330-0430  5.1   0    3        0  Peter Detterline (USA)
Nov 09  0746-0846  5.6   1    8   38   3  Peter Detterline (USA)
Nov 09  0846-0946  5.4   1    7   48   5  Peter Detterline (USA)
Nov 09  2220-2321  5.8   2   10   22   9  Alastair McBeath (UK)
Nov 09  2322-0022  5.8   2   10   26   8  Alastair McBeath (UK)
Nov 10  0022-0122  5.8   2   12   31   7  Alastair McBeath (UK)
Nov 10  0123-0228  5.8   0   18        0  Alastair McBeath (UK)
Nov 10  0655-0755  5.1   0    8        0  Mark Davis (USA)
Nov 10  0755-0855  5.2   0    8   32   0  Mark Davis (USA)
Nov 10  0855-0955  5.3   0    8        0  Mark Davis (USA)
Nov 10  1830-1900  4.0   0    3   17   0  C.L. Chan (Hong Kong)
Nov 10  2200-0000  6.0  (3)   8        -  Ulhas Deshpande et al. (India)
Nov 11  0001-0107  5.7   0   12   21   0  Joseph Zammit (Malta)
Nov 10  2323-0423  5.9   7   55   32   4  Martin Galea (Malta)
Nov 11  0257-0424  6.0   2   17   48   3  Joseph Zammit (Malta)
Nov 11  0356-0508  6.0   0    7   44   0  Alfredo Pereira (Portugal)
Nov 11  0330-0715  5.8   1    9   ~0   -  Mike Linnolt (USA)
Nov 11  0701-0801  5.3   0    7        0  Mark Davis (USA)
Nov 11  0801-0921  5.4   0   10        0  Mark Davis (USA)
Nov 11  1845-1913  5.8   0    2        0  Qi Rui (China)
Nov 11  1900-2000   -    0   19        0  Peter Zimnikoval et al. (Slovakia)
Nov 11  1910-2015  6.1   1    7   15   5  Jurgen Rendtel (Germany)
Nov 11  1913-2014  5.8   1   12   40   3  Qi Rui (China)
Nov 11  1900-2100  4.8   0    5    2   -  J. Marques, R. Afonso (Portugal)
Nov 11  1900-2115  5.9   0   14   15   0  Frank Enzlein (Germany)
Nov 11  1900-2130  5.8   0   15   15   0  Nikolai Wuensche (Germany)
Nov 11  2115-2130  5.8   1    5   55  10  Qi Rui (China)
Nov 11  2200-2300  6.0  (5)   8        -  Ulhas Deshpande et al. (India)
Nov 12  0022-0320  6.0   2   33   32   2  Umberto Mule Stagno (Malta)
Nov 12  0020-0324  5.8   2   41   33   2  Joseph Zammit (Malta)
Nov 12  0020-0340  5.9   3   39   34   3  Martin Galea (Malta)

I would like to thank all the above observers for their efforts and
swift reports, and I hope I did not overlook any message in this busy
time before the Leonids.

Rainer Arlt, 1999 November 13

NOTE: The WWW server of the IMO is down, probably until Monday, for
unknown reasons. Its site is alarm secured and cannot be accessed 
before Monday. Please apologize for the inconvenience.

IMO-news messages should be directly sent to the distributing
server at:


From Ron Baalke <>

Heavenly fireball puzzles Volusia County residents

November 12, 1999

DELAND, Fla. (AP) - A blue ball of fire that streaked across the sky
above Volusia County has residents wondering whether the sight was
something out of this world.

Clint Jones, who caught a glimpse of the hurling mass over DeLand
Tuesday night, is betting on a UFO.

'I believe it's possible,' Jones said from his home on the St. Johns
River. 'I know they exist.'

Police scanners indicated a number of residents saw the blue ball.

At 9:16 p.m., one anonymous caller told the Volusia County Sheriff's
Office he saw a fireball pass over the intersection of Clyde Morris and
LPGA boulevards. It was headed for Ormond Beach.

Sheriff's deputies, along with Daytona Beach police officers and a
sheriff's helicopter, searched for more than an hour. They found

The National Weather Service in Melbourne reported no unusual activity
Tuesday night. Officials at the Federal Aviation Administration tower
in Daytona Beach and the FAA Regional Office in Atlanta said they saw
nothing out of the ordinary.

'If a pilot would have seen it, they would have reported it,' FAA
spokeswoman Kathleen Bergen said.

Roger Hoefer, curator of astronomy at the Museum of Arts and Sciences
in Daytona Beach, speculated that people may have seen a Bolide meteor.
Bolide meteors appear to be falling, when in reality, they're simply
crossing the horizon.

'This was not falling,' Hoefer said. 'It was still moving in its
orbital path.'


From Explorezone, 11 November 1999

By Greg Clark, . 11.12.99

When the Near-Earth Asteroid Rendezvous spacecraft flew past Mathilde
in 1997, it returned several surprises to Earth.

By analyzing the deflection in the craft's flight path that the
asteroid's gravity caused, scientists calculated that Mathilde had a
density only 30 percent greater than water.

Mathilde's low density surprised many planetary scientists because
asteroids are thought to be composed of mostly solid, rocky material.
The least dense of the asteroid samples that have fallen to Earth as
meteorites are about 60 percent more dense than water. The most
persuasive explanation for the low density of Mathilde is that it is
very porous.

More puzzling than the density, though, were pictures of giant craters
that seemed completely free of surrounding debris. Craters are one of
the ubiquitous physical features of the solar system, and almost always
they are filled, covered and surrounded by the fragments of material
called ejecta. This is the material that is excavated by an impact,
explodes outward and then falls back to the surface, blanketing the
area in and around the hole. In craters the size of Mathilde's, but on
other asteroids, this ejecta is often kilometers deep. Mathilde,
however, is clean.

Now, laboratory modeling that simulates high-speed impacts that might
have occurred on Mathilde shows that the craters could have been
punched in like dimples into a Styrofoam ball rather than excavated

Researchers at the Boeing Company's Shock Physics Group in Seattle,
Wash. have found that under certain conditions, craters form in porous
material by compressing it, rather than throwing it out. The research,
lead by Kevin Housin, a research fellow at Boeing, is published in this
week's issue of the journal Nature.

One of the unique characteristics of porous materials was noted in the
1950s when the United States and Britain were testing atomic weapons on
coral atolls in the Pacific Ocean. Craters in these very porous corals
formed essentially by being crushed up as shock waves passed through.
In these craters, virtually all the material was compacted, not

This inspired the idea, Housen said, that perhaps the same kind of
collapse might occur with impact craters on Mathilde if it really is
very porous.

"Instead of forming a crater by digging a hole out and throwing the
material around the crater. You basically just squish it up, compact it
and compress it with very little ejecta being formed."

To test this idea, Housen and his colleagues used a high-speed
centrifuge with a hypervelocity gun mounted in the center. Spinning the
centrifuge to produce an artificial gravity 500 times that of Earth,
the team shot small nylon projectiles at a target material that had the
same density as Mathilde.

"If you look at the physics of how craters form," Housen explained,
"and want to conduct a small-scale experiment that correctly models a
very large crater on Mathilde, you have to form the crater at elevated
gravity. You want to reproduce the weight of material that is being
excavated on Mathilde."

Boosting the gravity makes a small amount of material behave like a
much larger mass of material.

"You can think of it as a wind tunnel for impact cratering," Housen
said. "People test the aerodynamics of how airplanes work by making
very small scale models. But they adjust properties of the fluid -- the
air that's flowing over them and the velocity so that they get things
simulated in the right way.

"By doing this experiment at 500 times normal gravity we can simulate
directly one of these large craters that form on Mathilde," he said. The
craters do indeed form without ejecta blankets.

Joe Veverka, who leads the imaging team for the NEAR spacecraft, said
this kind of impact modeling is what is needed to explain Mathilde's
curious craters.

The holes on Mathilde appear to have been formed right next to one
another, without affecting each other at all. "We would expect a huge,
catastrophic collision of this kind to cause major modification to the
craters nearby, but we don't see this happening," said Veverka, who is
chair of the astronomy department at Cornell University.

These very localized effects of large impacts suggest that Mathilde is
made of something that dampens the shock of impact, "basically like a
body made of shock absorbers," Veverka said.

People have suggested that a very porous body might be able to dampen
the shocks of impacts so that one crater might form next to another
without causing major landslides and such, Veverka said. This sort of
explanation has only been a vague suggestion, never tested with

Cautioning that he had not seen the results of Housen's work, Veverka
said that this type of study is necessary to figuring out how
Mathilde's craters formed.

The craters formed in Boeing's centrifuge also match Mathilde's craters
in this sense. In the porous material, the affects of craters remained
very localized. Craters could form right next to each other without
disturbing one another, Housen said.

The impact craters Housen's team produced do remarkably resemble those
found on Mathilde, but some scientists who have studied the asteroid
worry that the compaction explanation for the craters may raise more
questions than it answers.

William Merline, an astronomer at Southwest Research Institute in
Boulder, Colo. who studies asteroids, is one of those.

"It's a little hard to believe that you keep compressing the thing and
it still has a density of 1.3 (grams per cubic centimeter)," Merline
said. (Water has a density of 1 gram per cubic centimeter) "It would
seem like you would have to start with an even-lower-density body."
Mathilde's low density is hard enough to explain, Merline said. It is
even harder to imagine a body so porous that its density is the same
as water.

Housen, though, thinks that might be possible.

"If you calculate how much Mathilde should have compacted just by the
formation of those large craters that you see, it turns out that the
density might have been about 20 percent lower than what it is now."

An earlier Mathilde, uncompressed by cratering, would have had a
density very close to that of water.

"People tend to think that when the solar system formed, when you have
gas and dust settling down in a very quiescent kind of environment, you
may tend to build up these fluffy kind of objects," he said. "Unless
you get something that's fairly large -- much bigger than Mathilde --
it won't have enough self gravity to really squish itself up

Mathilde might be an early step in the evolution of heavier asteroids,
Housen suggests. Perhaps after a few more billion years of swinging
around the solar system and being pounded and compressed, it may come
to resemble the more dense, less porous rocks that have landed
on Earth as meteorites.

Copyright 1999, Explorezone


From Ron Baalke <>

Nature News Service

Press Release: November 11, 1999

Crushing Blow

In June 1997, the Near Earth Asteroid Rendezvous spacecraft flew past
the asteroid 253 Mathilde, sending back images of a crater-battered
world about 52 kilometres in diameter, with five giant craters each
over 20 km in diameter. Craters of such a size are generally surrounded
by blankets of ejected material several kilometres deep, but on
Mathilde there are no signs of such material.

The asteroid's unusually low density is thought to be part of the
explanation for this lack of ejected material, and this is now confirmed
by hypervelocity impact experiments carried out by Kevin R. Housen
of The Boeing Company, Seattle, Washington, and colleagues. These
experiments -- which involve firing projectiles at very high velocities
at samples of a porous material -- suggest that the craters are produced
by compaction, rather than excavation. Such a compaction process would
result in relatively little ejected matter being lost into space, explaining
why material from highly porous asteroids is a rarity in meteorites
reaching Earth.

Erik Asphaug of the University of California at Santa Cruz, California
discusses these findings in an accompanying News and Views article.

[NOTE: The News and Views article and full text of the paper are available
at .  Click on the item
"Crushing blow (11 November 1999)".]


From Jim Richardson <>

Hello colleagues,

Throughout the upcoming week, the American Meteor Society (AMS) will be
maintaining a Leonids '99 Update page at the AMS web site, located at:

The purpose of this page is to provide a narrative description, along
with eyewitness accounts, of the 1999 Leonid meteor shower as compiled
from reports received by the AMS and our affiliate group, the North
American Meteor Network (NAMN).  We are designing this page to act as a
compliment to the reporting efforts and analysis of the International
Meteor Organization (IMO), Dutch Meteor Society (DMS), and other
related groups. Although observed hourly rates and shower
characteristics will be given, we do not intend to offer a detailed
analysis or ZHR profile (leaving this to the other groups).  Instead,
we intend to compile a historical record of selected anecdotal accounts
and personal impressions of the 1999 Leonids.

Many of the accounts included on this page will undoubtedly come from
the MeteorObs mailing list, but we would *greatly* appreciate receiving
reports from all of the various professional and amateur Leonid
expeditions worldwide. If you would like to send us a narrative account
of your personal Leonid experience, in addition to the scientific data
collection which you are doing, I can receive your reports at the below
email address:

Jim Richardson <>

Selected narratives will be posted on the AMS web site as quickly as
possible, in addition to commentary on the overall shower activity,
with a final edited collection of Leonid accounts to appear in the next
issue of the AMS journal, Meteor Trails.  This was done with good
success last year, and it is hoped that these historical narratives
will prove to be a enjoyable companion to the numerous scientific
studies being performed.

Best regards,


James Richardson
Department of Physics
Florida State University (FSU)

Operations Manager
American Meteor Society (AMS)


From Andrew Yee <>

Office of Public Affairs
Columbia University
New York

November 8, 1999

Deep Ocean Current 'Seesaw' May Relate To Global Warming/Cooling Cycle
By Kurt Sternlof

In a display of far-reaching scientific opportunism and synthesis,
Lamont-Doherty Earth Observatory marine geochemist Wallace Broecker and
colleagues have used data on the distribution of an ozone-depleting
pollutant to shed light on a deep ocean mystery that could affect our
understanding of global warming.

Their paper on the subject appears in the November 5th issue of Science.

Deep ocean circulation is dominated by two "rivers" of sinking
seawater, Broecker explained. One deep-water source originates in the
North Atlantic, the other off the coast of Antarctica. In this way all
the water in the oceans is ventilated at the surface and mixed at depth
about once every 800 years.

The mystery lies in the fact that different chemical tracer methods for
measuring the rate of deep-water formation have yielded different
results -- a faster rate over the long term and, more recently, a
slower rate for the Antarctic source -- while other evidence suggests
that deep ocean circulation runs at a steady rate, with roughly equal
inputs from north and south over the 800-year mixing cycle.

Broecker's team turned to data on the pollutant chlorofluorocarbon-11,
better known as freon, to double-check the recent rates of deep-water
formation. Freon makes a perfect tracer, because it disperses quickly
in the atmosphere, is highly soluble in water, can be measured very
accurately, and was released only recently. Thus, the levels of freon
in deep-water samples provide a measure of how much surface water has
subsided to the depths over the past few decades.

The freon data was analyzed in a study led oceanographer Alejandro Orsi
of Texas A&M University.

According to Broecker's reading of that study, the current rate of
Antarctic deep-water formation is only one-third that of the North
Atlantic, where the rate matches the expectations of a steady-state
scenario. The freon data also suggests that no other significant, as
yet undiscovered deep-water source areas exist. Accommodating all the
data suggests to Broecker that the rate of Antarctic formation must
have changed dramatically over the last 800 years, from fast to slow.

"If I'm right, deep ocean circulation is not steady state process. That
concept is mind-boggling, and certainly open to debate," Broecker said.
"But it's reasonable to wonder whether deep ocean fluctuations could be
related to fluctuations in global climate. The potential consequences
of that are enormous, and provide a lot of fodder for scrutiny and
further research."

Broecker believes that such a relationship does exist. After all,
scientists have demonstrated that El Nino cycles are strongly tied to
fluctuations in the patterns of shallow ocean currents. Why wouldn't
changes in deep ocean currents also express themselves climatically? He
finds it tantalizing to look at the evidence for the Antarctic
slow-down and consider the possibilities.

Of particular interest is the relationship between the new data and
three well-established climatic phenomena.

First, that about 12,500 years ago deep-water formation in the north
virtually ceased during a pronounced cold event, while Antarctic
deep-water formation accelerated in conjunction with a relative warming
there. Second, that pronounced ice-rafting events related to cyclical
warming trends occur in the North Atlantic every 1,500 years. And
third, that a cooling event called the "Little Ice Age" occurred
between 1350 and 1880, since which the planet has warmed in two roughly
equal steps -- from 1880 to 1945 and from 1975 to present.

Within all this, Broecker sees the possibility that deep-water
formation continues to seesaw from north to south in association with
temperature changes on a 1,500-year cycle. If true, regardless of the
mechanism by which deep ocean currents affect climate, natural global
temperature changes can be expected to occur on a millennial time
scale. The question then becomes -- are we now in the midst of just
such a natural temperature shift and, if so, what would today's climate
be like in the absence of greenhouse warming?

"There's really no way we can tell at this point. It is just as likely
that natural forces currently retard the effects of greenhouse warming
as enhance it," Broecker said. "We don't know enough about these
natural climate shifts or how quickly they occur to be able to

Broecker does believe that the key to understanding humanity's role in
the current global warming trend lies in unraveling the demise of the
Little Ice Age -- what part of the two-step warming since 1880 is due
to greenhouse gases versus natural forces. And he hopes that his paper
will stimulate more interest and research in that direction.

That further research might disprove his notion of a deep ocean cycle
tied to climate is fine with Broecker. However, to those of his
colleagues who would attribute the current global warming trend
entirely to such natural causes, he says nonsense.

"It is ridiculous to argue that greenhouse gases are having no effect,"
he said. "The preponderance of evidence that they are warming the
planet is overwhelming, regardless of any underlying natural trend."


F.H. Chen*), Q. Shi, J.M. Wang: Environmental changes documented by
sedimentation of Lake Yiema in arid China since the Late Glaciation.
JOURNAL OF PALEOLIMNOLOGY, 1999, Vol.22, No.2, pp.159-169


In this study, a 6 m long core (16,000 BP) at the center of the dry
Lake Yiema, a closed lake of Shiyang River drainage in Minqin Basin of
the arid northwestern China, was retrieved to recover the history of
climate changes and lake evolution in the area. Five radiocarbon dates
on organic matter were obtained. A chronological sequence is
established based on these five dates and other dates from nearby
sites. Magnetic susceptibility, particle size and chemical composition
were analysized for climate proxies. The proxies indicate that a drier
climate prevailed in the Shiyang River drainage during the last
glacial. Lake Yiema was dry and eolian sand covered most part of the
lake basin. During the early and middle Holocene, a moister climate
prevailed in the drainage. Climate became dry stepwise with an abrupt
transition from one stage to another during the entire Holocene and
became driest since about 4,200 BP. Maximum dry climate spells occurred
at about 12,000-10,000 BP and after about 4,200 BP. A dry climate event
also existed at about 7,600 BP. Periodical sand storms with about
400-yr cycle happened during the middle Holocene. Desiccation processes
of the lake started at 4,200 BP, and were accelerated since the last
2,500 yrs by the inflow water diversion for agriculture irrigation.
During the past 2,500 yrs, the lake size has been closed associated
with the human population, implying that the human impact has been
accelerating the lake desiccation superimposed on the natural
climate deterioration. Copyright 1999, Institute for Scientific
Information Inc.


A.S. Gaur*) & K.H. Vora: Ancient shorelines of Gujarat, India, during
the Indus civilization (Late Mid-Holocene): A study based on
archaeological evidences. CURRENT SCIENCE, 1999, Vol.77, No.1,


Changes in the shoreline at any point could be due to various reasons
such as tectonic disturbance or shift in sedimentological regime
causing erosion or deposition. Many scientific investigations, focusing
on the palaeo-shoreline vis-a-vis sea level fluctuations in India based
on numerous geological techniques, have indicated that at about 6000
BP, the sea level was approximately 6 m higher than at present and
about 4000 years BP it stabilized at the present one with minor
fluctuations. Copyright 1999, Institute for Scientific Information Inc.


From Andrew Yee <>

Office of Public Affairs
Columbia University
New York

November 5, 1999

Another Innovative On-line, Multi-media Resource -- Columbia Earthscape
-- Launched by Columbia

By Lauren Marshall

In a bold departure from its paper counterparts -- scientific journals
that reproduce their print editions on-line -- Columbia and Columbia
University Press have launched Columbia Earthscape, the first
multi-media resource in the earth sciences designed for scientists and
laymen alike.

Described as one-stop shopping in the field of earth system science,
Columbia Earthscape contains current research, breaking news, policy
debates and curriculum models for Earth science teachers on a
wide-range of topics, such as climate change, oceanography, geology,
and environmental resources.

The site contains of over 70,000 pages of multi-media web content,
including full-text books,  video clips, current journal articles,
lectures and seminars, conferences, policy papers and commentary, maps
and models, searchable databases, links and live web-casts of important
conferences, from a variety of sources -- among them, Columbia, NASA,
MIT, the American Museum of Natural History and ABC News.

On Nov. 15 and 16, Earthscape will feature a live webcast of Lamont
Doherty Earth Observatory's The State of the Planet conference, which
will assess the state of the Earth from four standpoints: climate,
natural resources, natural hazards and humankind's impact on the

As the Earthscape site matures, 2,000 pages of information will be
added monthly.

By virtue of its medium, the World Wide Web, it is expected that
Earthscape will transform the way researchers, scholars, teachers,
students and decision-makers gain access to critical information in the
Earth sciences and environmental policy. The virtual publication is
expected to reduce the cost of scholarly information access and use,
and to expand the dissemination of scientific research to a wide
audience. It also has the potential to create a trend in on-line
curricular support for teachers in the field.

According to John Haber, editor of Columbia Earthscape, the site was
developed with scientists in mind, but is not exclusively for a
scholarly audience.

"Because science and environmental policy intrude on people's lives on
a daily basis, the site offers something for everyone," said Haber.

A quarterly on-line magazine Earth Affairs offers a forum for
scientists to exchange opinions and ideas. Breaking news engages the
general public, and while the site offers information in the earth
sciences for students, curriculum modules offer classroom tools for
science teachers.

"Earthscape provides an environment for experimentation in the science
curriculum thereby creating a community of teachers who are using
high-tech multimedia materials in the classroom," said Haber.

In addition to curriculum modules in eight areas of the earth sciences,
the site provides course models for others to follow, guidance on how
to approach particular issues in the classroom and ways to further
integrate current research and policy into undergraduate course

"With Earthscape we are attempting to bring easily searchable quality
content in a variety of media from a variety of resources," said Kate
Wittenberg, senior executive editor of Columbia University Press and
director of the Electronic Publishing Initiative at Columbia. "In a
university setting, because of our resources and expertise, we can move
swiftly and innovatively in the creation of interesting new models for

Columbia Earthscape is the newest scholarly publication in a generation
of innovative, interdisciplinary digital publications developed by
Columbia. Through the Electronic Publishing Initiative at Columbia (the
EPIC Center) established this summer, innovative on-line publications
are explored, developed, and evaluated as digital solutions to the
current crisis in scholarly publication: growing publishing costs in a
shrinking market for scholarly books.

Like Columbia International Affairs On-line, the first 
multi-disciplinary on-line venture of its kind in the field of
International Affairs, which was launched by Columbia two years ago,
Columbia Earthscape is the result of a collaborative effort between the
Columbia University Press, the University Libraries, and Academic
Computing Information Systems (AcIS).

"The groundwork for Earthscape was set when we began planning for the
Columbia Digital Library. This work gave us much insight into the
viability of on-line resources in academic settings," said Elaine
Sloan, vice president for Information Services and University
librarian. "Since that time, our commitment to the development of the
digital library has grown. One of the outcomes is the creation of EPIC,
an organization that draws from the expertise of a range of minds
within the University: faculty who create knowledge, information
technologists who create the complex architecture and security of EPIC
sites, librarians who contribute their expertise in the collection and
organization of information, and Columbia University Press'
contributions as publishers."

In addition to a start-up grant from the Office of the Provost,
Columbia Earthscape has received two three-year grants assisting in the
development, launch and staffing of the publication, including $590,000
from the National Science Foundation's Digital Library 2 Program and
$200,000 from SPARC, the Scholarly Publishing and Academic Resources
Coalition. According to the Director of SPARC, Rick Johnson, Earthscape
was one of three digital initiatives awarded grants because of their
"enormous potential to transform the scientific information economy"
and "general benefit to science, academe and society at large."

Columbia Earthscape, located at, is accessible to
the Columbia community free of charge via Columbia Net. The site will
be available for subscription to both institutions and individuals in

For more information on digital projects at Columbia contact Kate
Wittenberg at (212) 666-1000, ext. 7119 or or visit
the earthscape site at


H.H. von Muldau*): Space education, a tool to influence the cultural
development in the society. ACTA ASTRONAUTICA, 1999, Vol.44, No.7-12
SISI, pp.803-807


Culture is an organized group of learned responses of a particular
society, or the total round of human activities, not due to
heredity, shared by members of a group. This means that culture is
a dynamic process and it is in tight relationship to the
civilization as a tool to master their all day's tasks. Space
science is a result of the shift from the mass production
civilization to the knowledge civilization. The science had opened
new ways of thinking into a new environment, space. The ability to
develop thinking to new living areas is already a Learned response
to the environment and therefore an act of culture. The next
changes in culture are a result of the different view, mankind has
From earth looking back out of the spacecraft window. We see now
with other eyes the small and vulnerable living area of mankind.
We see no political limits partitioning the surface. We understand
time zones as systems properties of the regions. This has up to
now influenced big groups of the societies. As this view has to be
shared by all members of the societies in the same mode, space
education has to organize this effect. (C) 1999 Published by Elsevier
Science Ltd. All rights reserved.

The CCNet is a scholarly electronic network. To subscribe/unsubscribe,
please contact the moderator Benny J Peiser < >.

Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at


LETTERS TO THE MODERATOR - CCNet, 15 November 1999

    Erik Asphaug <>

    Terry Richardson <>

    Duncan Steel <>

    Bill Napier <>


From Erik Asphaug <>

Dear Benny,

Roy Tucker is right, that a low-density object is easier to "shove
around" than a high-density object, all things being equal. However
it's not as simple as that, since the material and structural
properties themselves determine how energy and momentum are coupled  to
a target.

For example, Stan Love and colleagues once fired identical bullets into
cylinders of glass, and into cylinders of sintered glass beads. Where
the aggregate targets formed a modest crater, the homogeneous (and
more dense) targets flew apart into scattered fragments. We are
basically seeing the same thing in our asteroid impact models.

With regard to shoving asteroids around, it should be remembered that
an explosion does not contribute momentum directly.  Rather, pieces
flying away at high speed cause the equal but opposite rebound that
diverts the asteroid. (In laboratory impact experiments, it is
not uncommon for the largest remaining fragment to be moving _towards_
the rifle, because of fragments ejected from its back side!)  If very
little material escapes the "ground zero", there will be
correspondingly little change in the asteroid's momentum.

So the bottom line is, a very porous asteroid might be difficult to
divert or disrupt by standard ("Deep Impact" or "Armageddon") methods. 
On the other hand, its low density would make it easier to divert by
direct momentum coupling, e.g. by a solar sail, by kinetic mass
excavation, or by localized thermal devolatilization (outgassing),
given enough advance warning. The notion of a standoff burst, as
explored  by Al Harris and Tom Ahrens, also has promise, and needs to
be revisited for highly porous, probably compactible surfaces.

We would be fools, of course, not to take our time to thoroughly
understand asteroids before implementing any idea which might involve
gigaton warheads in space. This is no emergency, and missions such as
Deep Impact are the perfect type of necessary exploration at this

Whether asteroids are "flying Rice Krispie treats" -- a colorful
(flavorful?) description of the type of hyperporous, compactible bodies
proposed by Housen et al. in this week's issue of Nature -- or some
other kind of structure, my first recommendation is for those curious
about such mechanisms to go to the article itself (available at most
news stands) and references therein, rather than settling for filtered
news content which of necessity simplifies a complex story. 

My second recommendation is for the public to speak up for missions
which will probe the physical nature of asteroids and comets.  They are
strangely difficult to understand, and more intricate than we have yet

Erik Asphaug
University of California, Santa Cruz


From Terry Richardson <>

Dear Dr. Peiser,

Fluffy asteroids provide an alternate means of deflection should one be
aimed at the earth and we reach the level of technology to deflect
asteroids. Based on the idea of an ion engine where a small amount of
mass propelled continuously over a period of time can accelerate a
rocket to high speeds, a mechanism could be landed on such an asteroid
that launches parts of the asteroid into space, reloads and continues
to do so gradually deflecting the orbit away from the earth. Perhaps a
longer lead time might be necessary in the discovery of such asteroids
to employ such a system, but loosely organized material of the right
nature should make such a system possible.


Terry Richardson

Department of Physics and Astronomy
College of Charleston
Charleston, SC 29424
pager #937-1048
843 953-8071 phone
843 953-4824 fax


From Duncan Steel <>

Dear Benny,

The 19th century mathematician Augustus De Morgan, who was Secretary of
the Royal Astronomical Society, wrote that one can tell the true
paradoxer by the extent to which he (De Morgan would write only 'he'
despite being the tutor of Ada Byron) had or had not studied the work
which had previously been done on some topic of mathematics or natural
science. That is, had the paradoxer read and understood the literature?

In my review in Sky and Telescope I wrote that Hoyle and Wickramasinghe
had published their hypothesis in 1978. I was working from memory when
I wrote that, but it took me less than 60 seconds to find the full details plus
abstract via the internet:

F. Hoyle and N.C. Wickramasinghe: Comets, ice ages, and ecological
catastrophes. Astrophysics and Space Science, volume 53, number 2, pp.
523-526 (1978).

A total mass of the order of 10 to the 14th power grams added to
earth's upper atmosphere in the form of small particles of high albedo
for visual wavelengths would produce an inverse greenhouse effect,
shielding ground level from sunlight but permitting infrared radiation
from the ground to escape into space. Such a mass of small particles
might be acquired by earth in a close approach to a cometary nucleus.
Ice ages and ecodisasters, such as that which occurred 65 million years
ago, could arise from the effects of such an addition of small 

Now, the authors may well have been wrong in their hypothesis and
analysis, but that requires them to be judged on what they did/wrote
and *not* on what some others may just think that they did/wrote. To
that extent recent messages discussing the dust and/or sulphur injected
into the (lower) atmosphere by volcanic eruptions has no bearing upon
the question in hand, which pertains to the possible climatic effects
of the deposition of substantial amounts of cometary dust into the
upper atmosphere/mesosphere, where the physics involved is quite
different. If one is interested in the question, why not simply look up
the Hoyle and Wickramasinghe paper and see what is involved?

Duncan Steel


From Bill Napier <>

Dear Benny,

Lack of time doesn't allow me to do justice to your query (I'm on leave
trying to meet a deadline for another novel!). However I can comment
briefly on the basic astronomical model for dusting. We should be
thinking, not in terms of 20 km single-flyby comets, but rather of
100-200 km diameter comets thrown into short-period, Earth-crossing
orbits. These yield repeated stratospheric dustings with cyclic inputs
on various scales, and also a zodiacal cloud with a mass enhanced by
two orders of magnitude or so over periods of many millennia. Giant
comets are easily the dominant mass input to the inner planetary system
on say 100,000-year timescales.

There are now quite a few papers in the refereed literature, by various
authors, showing that significant atmospheric perturbations are
expected. This is a very active area, relevant to many academic
disciplines as well as Spaceguard, and papers will be along in due

Best regards

Bill Napier

CCNet-LETTERS is the discussion forum of the Cambridge-Conference
Network. Contributions to the on-going debate about near-Earth objects,
the cosmic environment of our planet and how to deal with it are
welcome. The fully indexed archive of the CCNet, from February 1997 on,
can be found at

CCCMENU CCC for 1999