PLEASE NOTE:
*
CCNet 106/2000 - 19 October 2000
--------------------------------
"The idea that methane has caused
extinctions in the past has no more
credibility than the 'Bermuda Triangle
literature.'"
-- Roger Sassen,
Texas A&M University, 18 October 2000
(1) TEXAS FIREBALL IDENTIFIED AS RUSSIAN SATELLITE RE-ENTRY
Mark Kidger <mrk@ll.iac.es>
(2) WEEKEND METEORS
NASA Science News for October 18, 2000
(3) EROS IS NASA'S LITTLE PRINCE
Larry Klaes <lklaes@bbn.com>
(4) NEAR AT EROS: DANCING THE TANGO
Ron Baalke <baalke@zagami.jpl.nasa.gov>
(5) PRECOVERY WORK ON NEAS
Andrea Boattini <boattini@ias.rm.cnr.it>
(6) GLOBAL WARMING SCARE GOES OTT: DID IT CAUSE MASS EXTINCTION
55 MYA?
Boston Globe, 17 October 2000
(7) DON'T LAUGH: CLIMATOLOGISTS CLAIM COLD WINTERS CAUSED MASS
EXTINCTION 34
MYA
The New York Times, 19 October 2000
(8) NO EVIDENCE OF DEGLACIATION
CO2 Science, 18 October 2000
(9) 6000 YEARS OF SEA LEVEL CHANGE IN THE SOUTHERN HEMISPHERE
CO2 Science, 18 October 2000
(10) SPACE EXPLORATION: THE CHINESE CENTURY?
Michael Martin-Smith <martin@miff.demon.co.uk>
==========
(1) TEXAS FIREBALL IDENTIFIED AS RUSSIAN SATELLITE RE-ENTRY
From Mark Kidger <mrk@ll.iac.es>
Dear Benny:
The bright fireball seen over Texas, Oklahoma and Kansas on the
13th has now
almost certainly been identified as the re-entry of the Proton
booster of a
Russian Glonas satellite. The groundtrack of the booster,
calculated by Alan
Pickup
http://www2.satellite.eu.org/sat/seesat/Oct-2000/0235.html
agrees well with the estimated groundtrack of the fireball.
Curiously, a NORAD spokeperson has suggested that the fireball
may have been
an early Orionid meteor, but this now seems highly unlikely.
More detailed information on the event can be found at
http://meteors.com/cometlinear/index.shtml
Unlike the Los Alamos fireball reported on CCNet recently, this
event is
almost certainly man-made.
Mark Kidger
=============
(2) WEEKEND METEORS
From NASA Science News <snglist@lyris.msfc.nasa.gov>
NASA Science News for October 18, 2000
http://science.nasa.gov/headlines/y2000/ast18oct_1.htm?list20392
October 18, 2000 -- Last Friday, the 13th of October, thousands
of
high-school football spectators were gathered in outdoor stadiums
across the
Midwestern US when something happened to distract even diehard
fans from
action on the field below.
With no warning, a fiery meteor as bright as the full Moon
streaked over
Texas, Oklahoma, and Kansas around 7:30 p.m. local time. It was a
halftime
show from the heavens!
"At first I thought it was a high-flying aircraft with its
landings light
on," recounts Alex Leslie, who saw the meteor from a Hill
City, Kansas,
football game. "As it passed almost directly south of us, it
separated into
about five burning points, mainly white but some green hues, too.
A 'smoke
trail' lingered for some time after the object passed. It took
about five
minutes to cross the entire sky."
Emergency phone lines were jammed with UFO reports soon after the
sighting,
but in this case the strange lights were not from outer space.
The object
that slowly burned across Texas skies had left Earth only hours
before.
Earlier on Friday a trio of Glonass satellites lifted off from
the Baikonur
Cosmodrome in Kazakstan aboard a single Russian Proton rocket.
Glonass is
the Russian equivalent of the American Global Positioning System.
The
successful launch added three new satellites to the Glonass array
and,
unintentionally, triggered the Friday night sky show over Texas.
"In my opinion, the [Texas fireball] was the re-entry of the
Proton rocket's
4th-stage casing," says Alan Pickup, a satellite decay
expert who works at
the United Kingdom's Astronomy Technology Centre at the Royal
Observatory in
Edinburgh. "It was a cylinder 3.7m in diameter and 4m long
that weighs some
800 kg."
"The object had passed through perigee (closest approach to
Earth) at 7:19
p.m. Central Daylight Time (00:19 UT) when it was over the
eastern Pacific
en route to the Mexico coast. It would have passed 3.1 degrees
west of
Abilene, Texas, at 7:25 p.m. (00:25 UT) and almost directly over
Lubbock,
Texas, 19 seconds later. Its track continued over Oklahoma and
Kansas
towards Lincoln, Nebraska, which it would have reached at about
7:27 p.m.
local time were it still in orbit."
But there is a real meteor shower in store this weekend for
erstwhile star
gazers inspired by Friday's fiery display.
Earlier this month our Earth's orbit carried our planet into a
diffuse
stream of dusty debris from Halley's comet. Until now we've been
in the
rarefied outskirts of the debris field, but we're heading for
denser parts.
Tiny bits of Halley dust that burn up in our planet's atmosphere
will
produce a meteor shower, called the Orionids, that peaks this
weekend,
October 21st and 22nd. Orionid meteors won't be nearly as bright
as a
decaying Proton rocket shell, but the display should be
nonetheless
pleasing.
Earth passes close to the orbit of Halley's comet twice a year,
once in May
and again in October. Although the comet itself is very far away
--
presently beyond the orbit of Jupiter -- tiny pieces of Halley
are still
moving through the inner solar system. These particles are
leftovers from
Halley's close encounters with the Sun every 76 years; each time
the comet
returns, solar heating evaporates about 6 meters of ice and rock
from the
nucleus. The debris particles, usually no bigger than grains of
sand,
gradually spread along the comet's orbit until it is almost
uniformly filled
with tiny meteoroids. When these meteoroids strike Earth's
atmosphere they
produce the Orionid meteors in October and the eta Aquarid
meteors in May.
No matter where you live, the best time to see Orionid meteors
will be
during the hours before dawn on October 20th through 23rd. Rural
observers
should enjoy as many as 20 shooting stars per hour. During this
year's broad
peak, centered approximately on Oct. 21st, the light of the
waning quarter
Moon will make faint meteors hard to spot; pre-dawn observers on
the 22nd
and 23rd may have better luck with diminishing moonlight.
Orionid meteoroids are fast. They hit the atmosphere at a
head-spinning
velocity of 90,000 mph. There's no danger, though, because the
tiny specks
of dust disintegrate well above the stratosphere. True to their
name, the
Orionids will appear to stream from the constellation Orion,
which is high
in the southern sky before dawn. The best place to look for
meteors is not,
however, directly toward Orion. Orionids can appear anywhere in
the sky,
with tails that point back to the shower's radiant above Orion's
left
shoulder. Experienced meteor watchers suggest looking 90 degrees
away from
the constellation -- that's usually the best direction to watch
Orionids fly
by. Also, try to choose a dark area of the sky away from the
bright Moon.
Even if the usually-reliable Orionids fail to produce a pleasing
show,
there's still plenty to see. October's glittering pre-dawn sky
includes
Jupiter, Saturn, and the brightest star of all, Sirius -- all
near to the
Orionids radiant. Waking up early for this weekend's meteors is a
no-lose
proposition!
=============
(3) EROS IS NASA'S LITTLE PRINCE
From Larry Klaes <lklaes@bbn.com>
From Boston Globe, 17 October 2000
http://www.boston.com/dailyglobe2/291/science/Eros_is_NASA_s_Little_Prince+.shtml
By Chet Raymo, Globe Correspondent, 10/17/2000
Antoine de Saint-Exupery's "Little Prince" lived on an
asteroid scarcely
larger than himself. As readers of the childhood classic will
remember, his
companions were a sheep and a rose, and some baobab seedlings
that he
carefully weeded, lest they grow into giant trees that would
split his tiny
world. The asteroid had three volcanoes, two of which were
active, and all
of which the Little Prince assiduously cleaned.
A charming little world, but of course scientifically
implausible. An
asteroid the size of the Little Prince's would not have enough
internal heat
to cause volcanic activity, nor enough gravity to hold an
atmosphere. Water
too would be absent, and surface temperatures would be either too
hot or too
cold for comfort.
For his journey to Earth, the Little Prince took advantage of the
migration
of a flock of wild birds, to which he attached himself with
cords. On a
world as small as his, birds might well provide enough propulsive
power to
effect an escape - if only there were air in space in which to
fly.
Where children fly in their imaginations, NASA takes us in
reality. On Feb.
17, 1996, the NEAR, or Near Earth Asteroid Rendezvous spacecraft
was
launched on a four-year voyage to the asteroid, Eros. Not a flock
of wild
birds but a Delta rocket with nine strap-on boosters lifted the
car-sized
craft away from Earth and sent it on its way.
Eros is not so far away. It doesn't circle in the asteroid belt
between Mars
and Jupiter, but on an eccentric orbit that takes it nearly as
close to the
sun as Earth, and out just past Mars. Eros was the first
near-Earth asteroid
to be discovered, and the second biggest. It is a potato-shaped
chunk of
rock about the size of Martha's Vineyard. Not as small as The
Little
Prince's world, but small enough to circumnavigate in a brisk
day's walk.
NEAR's voyage to Eros took four years. A three-year journey was
planned, but
the first attempt to put the spacecraft into orbit around the
asteroid
failed. An extra year's travel gave engineers time to trim their
skills and
calculations. And it allowed NEAR to rendezvous with an asteroid
named for
the god of love on Valentine's Day 2000.
An object as small as Eros doesn't have much gravity to hold a
spacecraft in
orbit. The Little Prince would weigh about an ounce on Eros, and
he could
launch a stone into space with a swing of his arm. NEAR is bound
to Eros by
a slender gravitational thread, and slipping the spacecraft into
the thrall
of the asteroid was a tour de force of remote navigation.
Since April, NEAR has been orbiting just above the lumpy surface
of Eros,
sending back stunning pictures of a gray and lifeless world
without air or
water (http://near.jhuapl.edu).
No sheep or baobabs, but lots of impact
craters and scattered boulders. We are catching a glimpse into
the early
history of the solar system, when scattered dust and gas was
gathered into
larger and larger chunks of rock, some of which would eventually
coalesce to
form the planets, and others that were destined to drift through
space like
gloomy Flying Dutchmans.
That's exactly the impression one gets from the NEAR photos of
Eros. It's as
if a manned boat had pulled aside the spectral galleon of
seafaring myth,
hailing without answer for a human response. The lifeless
asteroid sails on
in dusty solitude, grimly colorless and deathly silent, reminding
us of just
how extraordinary and rare is life in the universe.
A recent issue of the journal Science brought us the first
summary reports
from NEAR. We have the mass, shape, rotation rate, elemental
composition,
and even something of the asteroid's internal structure. The
potato-shaped
rock named after the god of love is no longer just a speck of
light in a
telescope; it is now a world as exactly accessible to our
imaginations as
the Little Prince's domicile.
Astronomer's have charted about 250 near-Earth asteroids, and
there may be
as many as 1,000 with a diameter of a half-mile or more. A few of
these are
probably destined to collide with Earth at some time in the
future, as other
asteroids have done in the past. If something like Eros came
smashing our
way, we would be in big, big trouble indeed. Fortunately, Eros is
on an
orbit that will keep it safely out of the way.
But NASA scientists plan to get our licks in first, anyway. Next
year, two
days before the first anniversary of the Valentine's Day
rendezvous, NEAR
will be caused to collide with Eros while the scientists listen -
one last
attempt to extract information from an asteroid that has been
clobbered
enough in its long history to withstand a gentle assault from
Earth.
Chet Raymo is a professor of physics at Stonehill College and the
author of
several books on science.
This story ran on page F2 of the Boston Globe on 10/17/2000.
© Copyright 2000 Globe Newspaper Company.
================
(4) NEAR AT EROS: DANCING THE TANGO
From Ron Baalke <baalke@zagami.jpl.nasa.gov>
http://near.jhuapl.edu/news/sci_updates/00oct17.html
NEAR
Shoemaker Science Update
October
17, 2000
Dancing
the Tango
NEAR is
now eight months into its year-long rendezvous
with Eros.
We have seen Eros from as low as 35 km orbit
for about
ten days back in July, but then returned to
higher
altitude. For the last five weeks, we have been
mapping
Eros from 100 km orbit, but we are now preparing
for our
closest descent yet, a 6 km flyover scheduled
for
October 25, 2000. Why has NEAR Shoemaker performed
this
elaborate tango with Eros? One answer is that we
chose one
of the most attractive partners on the dance
floor, and
we have to pay the price if we wish to dance
very close
- it costs extra fuel and requires frequent
maneuvers.
But another reason for dancing both up close
and
farther out is that we scientists want it that way.
The design
of the mission has been the result of a
complicated interplay between science and engineering
requirements. To start with, NEAR Shoemaker was designed
as a
simple spacecraft, with fixed antennas, fixed solar
panels,
and fixed instruments. This simplicity makes for
a more
reliable and robust spacecraft, but it also
places
operational constraints on the mission. The
spacecraft
must always keep its solar panels pointed at
the sun -
it cannot survive even for an hour without
solar
power, not only because the electronics would stop
operating,
but also because instruments and subsystems
would be
damaged by cold and the fuel would quickly
freeze.
The instruments must be pointed at the asteroid
in order
to acquire data. The main antenna must be
pointed at
Earth to send data back to Earth at high
rate,
although the spacecraft status can be monitored
and the
spacecraft can be tracked at lower data rates
using
other antennas, even when the main antenna is not
pointed at
Earth. If we had designed a more complex
spacecraft, we could have lifted many or all of the
operational constraints, but it would have cost more.
And indeed
these restrictions complicate the day-to-day
operations
of the spacecraft, but it turns out that the
ever-vigilant enforcement of simple rules is a task
better
suited for computers than for humans, and this
task is
largely automated for NEAR. Paradoxically, the
use of a
simple spacecraft leads to an overall
simplification of mission operations, despite
operational restrictions, because there are fewer
options to
be studied.
In any
case, the spacecraft design constrains NEAR
Shoemaker
to fly in an orbit plane that is within about
30 degrees
of perpendicular to the line from Eros to the
Sun. The
spacecraft can then keep its solar panels
pointed at
or close enough to the Sun at all times,
while for
16 hours a day it keeps the instruments
pointed at
Eros for data taking, and for 8 hours a day
it points
the main antenna at Earth for data
transmission. This tight constraint on the orbit plane
at Eros,
plus the constraint that the orbit is flown at
a
particular time, already fairly well settle three of
the six
parameters required to specify an orbit
completely. In some sense the orbit is now almost
halfway
designed, although in real life our engineers
determine
these parameters to 10 decimal places. Those
of us who
don't actually have to fly the spacecraft can
afford to
take a more relaxed attitude. The remaining
three
orbit parameters deal with how low and how high
the orbit
goes, and precisely where it dips low.
That is
where science comes in, although even at this
point
operational constraints are still critical. Some
of our
science operations are best performed at higher
altitudes,
while others require that the spacecraft be
at low
altitude. For instance, our imaging team desires
to map the
whole asteroid under a variety of lighting
conditions
and from a series of orbit radii,
specifically 200 km, 100km, and 50 km. In addition, the
team
requires both monochrome (black-and-white) and
color
imaging, and the ideal lighting conditions for the
one are
not ideal for the other. For monochrome images,
we prefer
the sun to be low in the sky so that shadows
accentuate
the structures, whereas for color images we
prefer the
sun to be higher to reduce the shadowing. In
addition,
there are seasons on the asteroid. Until late
June of
this year, portions of the southern hemisphere
never came
into sunlight at all. The reverse is now true
in the
southern hemisphere summer, when the north polar
region is
always in the dark. Beyond all these
requirements, the x-ray and gamma ray teams need to have
the
spacecraft in low orbits of 50 km or less as long as
possible
to achieve the highest possible signal-to-noise
ratio.
Also the laser rangefinder team obtains the
highest
resolution and measurement accuracy in the low
orbits,
and the study of the asteroid's interior
structure,
through determination of its gravity and
magnetic
fields, achieves the highest sensitivity in the
low
orbits.
So there
are many science tasks that require low orbits,
but there
are also science tasks that require high
orbits,
and in both cases, the spacecraft is required to
fly over
all parts of the asteroid at the altitudes in
question.
In addition, particular solar illumination
geometries
are often required, such as for color and
spectral
observations as well as the x-ray measurements.
Hence the
choices of how low to fly, and where, and
when, are
complicated, and we really needed to spend a
full year
at Eros. Moreover, there are engineering
requirements which derive from orbit stability. The
spacecraft
cannot be put into an orbit that would be so
unstable
that we could not predict with sufficient
accuracy
where it would be a week later, or so unstable
that, if
for any reason we could not contact the
spacecraft
or correct its orbit for a week, it would
crash or
escape from the asteroid. Furthermore, we avoid
orbits
that would require excessive fuel expenditures or
corrective
maneuvers more often than once a week.
Finally,
we cannot send the spacecraft into an orbit
that would
carry it into the shadow of the asteroid,
where the
Sun would be eclipsed and the spacecraft would
die.
Generally
speaking, the orbits we need to worry about
are the
low orbits. As we discussed earlier (April 18,
2000), the
irregularity of an object's shape produces
greater
and greater distortions of its gravity field,
the closer
one approaches to the object. At large
distances
from any object, its gravity field becomes
monopolar
and spherical, so higher orbits tend to be
better
behaved in terms of being more like ordinary
elliptical
orbits. There is a caveat, which is that the
gravity
from the object must remain the biggest force
field
around; if we get too far from the object, then we
also have
to worry about other forces like solar gravity
and
radiation pressure, and orbits become complicated
again. For
Eros, too high in this sense means above
about 1000
km. Hence the 200 km orbits are fairly stable
and
ordinary - that is, not too close and not too far.
The 50 km
orbits, on the other hand, are close enough to
be
strongly perturbed by the irregular shape of Eros.
The most
serious disturbance is that the orbit plane is
continually torqued around (that is, it precesses), so
it would
quickly violate the operational constraint we
started
with unless we perform maneuvers to correct the
orbit. In
other words, we need to fire the rocket
engines to
keep the orbit plane within the allowed
angles to
the line from Eros to the Sun. It turns out
that the
precession rate depends on the orbital
inclination to the Eros equator as well as the orbital
radius.
The upshot
is, there are only certain times of year when
NEAR
Shoemaker can fly in 50 km orbits or lower, without
using too
much fuel or putting the spacecraft at too
much risk.
Even so, we have no choice but to get up
close to
Eros to make the measurements we need. This is
why we are
dancing a tango with Eros, sometimes close,
and
sometimes far. Like the real tango, our dance with
Eros has
been exciting, full of mystery, and much hard
work - and
more is still to come. Our closest view of
the
surface to date is eight days away.
Andrew Cheng
NEAR Project
Scientist
================
(5) PRECOVERY WORK ON NEAS
From Andrea Boattini <boattini@ias.rm.cnr.it>
[as posted on the MPML Mailing list - mpml@egroups.com]
I have posted a brief report of the precovery work done at
Edinburgh at:
http://www.arcetri.astro.it/science/aneopp/sumedinb.htm
Also, I want to send my congratulations to Andrew Lowe on his
recent
NEA precoveries using DSS images.
Best regards,
Andrea Boattini
===============================================
Andrea Boattini
IAS-CNR, Area di Ricerca Tor Vergata
Via Fosso del Cavaliere 100
00133 Roma, ITALY
Phone: +39-06-49934448
Fax: +39-06-20660188
E-mail: boattini@ias.rm.cnr.it
===============================================
http://www.arcetri.astro.it/science/aneopp/sumedinb.htm
Looking for NEOs on the UK Schmidt Archive: a Preliminary Report
One of the most extensive and well maintained photographic
archives in the
world, is the UK Schmidt archive. Although some of its data is
available
through the web as part of the Digitized Sky Survey, the great
bulk of this
resource is kept at the Royal Observatory, Edinburgh (ROE). About
17,000
plates are there at any time.
The UKST archive has always represented a great potential for NEO
precovery
work. Considering the amount of success of other similar programs
from the
early 90's, we realized that a visit to ROE was worthwhile at
this stage of
the NEO discovery process. All single-opposition and a few
multiple-opposition NEOs were checked against the UKST catalog
file. Each
target output was divided into a few different categories
depending on the
likelihood of locating the object.
A collaboration was established with ROE staff for the use of
their plate
library, and we arranged a visit from September 19 to to October
3, 2000.
The work at ROE plate library, (object searching and astrometry)
was done by
Andrea Boattini. All the computational work,
"last-minute" observing
predictions and orbital linkages of possible candidates, was
performed by
Giuseppe Forti from Arcetri Observatory. Technical assistance at
ROE plate
library was provided by Mike Read and occasionally by Sue
Tritton. We plan
to arrange another visit in the near future, as soon as there is
enough
material and/or we have valuable scientific expectations to
justify another
trip to this nice facility.
Here is a brief summary of the results:
* NEOs found and measured: 24
One-opposition: 22
1999 RM28 (*), 1998 YB8, 1999 JU3, 2000 JS66, 1998 WM, 1999 KX4,
1999 RR28,
2000 QP,
1998 OR2, 2000 EZ148, 1998 UT18, 1998 BX7, 1999 GJ2, 1992 BL2,
1999 YB, 2000
NF11,
2000 SY2, 1999 JV3, 1999 LQ28, 1999 RP36, 2000 JT66, 2000 PG5
(*) located and measured by R. H. McNaught at Siding Spring
Observatory.
Multi-opposition: 3
1997 WS22, 1996 AS1, 2000 SY2 (addit. image)
* NEOs found but not measured (either plate defects or too faint
for
astrometry): 6
1997 XF11, 1998 UL1, 1999 AR7, 1999 CT3, 1999 DB7, 2000 JQ66
* NEAs not found (either too faint, not recognized, or out of
plate): 61
1977 VA, 1978 CA, 1983 LB, 1987 SF3, 1988 RO1, 1988 SM, 1991 FB,
1993 HC,
1995 QN3,
1996 PC1, 1997 AQ18, 1998 CS1, 1998 HM3, 1998 HJ41, 1998 ME3,
1998 QE2, 1998
SV4,
1998 SF35, 1998 SR49, 1998 VR, 1998 YM4, 1999 CZ136, 1999 FB,
1999 GT6, 1999
HV1,
1999 KK1, 1999 LN28, 1999 MN, 1999 SK10, 1999 TB10, 1999 VQ6,
1999 WA2, 1999
YA,
1999 YN4, 2000 BH19, 2000 CK33, 2000 CN33, 2000 CE59, 2000 CF59,
2000 CH59,
2000 CO101,
2000 EV70, 2000 EE104, 2000 EA107, 2000 FL10, 2000 FN10, 2000
FO10, 2000
GX127, 2000 GK137,
2000 HW23, 2000 JH5, 2000 JO78, 2000 OJ8, 2000 OB22, 2000 PJ5,
2000 QT7,
2000 QU7,
2000 QW69, 2000 RD34, 2000 RJ34, 2000 RH60
The above lists involved about 150 plates. Among the best finds,
we can
mention the lost Amor 1992 BL2 and the Aten 2000 SY2, which was
located
about three hours after the discovery announcement by the MPC. We
also
discovered one Hungaria (1977 SU3); it happened to be on four
plates leading
to a 55-days arc orbit. Another set of 150 plates have been used
to search
for a few lost objects, such as:
1937 UB, 1950 DA, 1991 NT3, 1991 TB2, 1998 FH74, 2000 KB
There was not enough time to make a full investigation of these
targets, but
in the case of 1991 NT3 the coverage of the confidence region was
almost
complete. We plan to use this information for a direct recovery
at the
telescope.
Note: A few plates we were interested in, were not at the ROE
plate library.
On one of these, 1999 RM28, was located measured by Robert
McNaught at
Siding Spring Observatory. Another plate where supposedly 1999
LP28 was
recorded, is currently in Japan.
Acknowledgements
We want to thank all the institutions that made this
collaboration possible:
the Royal Observatory at Edinburgh, the Rome Observatory and the
Arcetri
Observatory. Also, I want to send my congratulations to Andrew
Lowe on his
recent NEA precoveries using DSS images.
===========
(6) GLOBAL WARMING SCARE GOES OTT: DID IT CAUSE MASS EXTINCTION
55 MYA?
From Boston Globe, 17 October 2000
http://www.boston.com/dailyglobe2/291/science/Gas_attack+.shtml
Gas attack
It seems as harmless as a wilted flower, but methane gas once
caused a mass
extinction. It could happen again
By Gareth Cook, Globe Staff, 10/17/2000
Under the long shadow of the freshly carved Rocky Mountains,
delicate
creatures that looked like a cross between a squirrel and a
monkey noisily
foraged for food in the dense canopy of broad-leafed banana
trees. Off the
coast of Florida, dozens of species of tiny animals called
foraminifera
swarmed through the cerulean seas.
Then, in a geological instant, came chaos.
With a speed that has long baffled climatologists, the world's
temperatures
suddenly soared 55 million years ago, opening northern land
routes between
the continents. Whole families of archaic animals, including the
squawking
squirrel-monkies (plesiadapiformes), were doomed as an army of
new animals -
including the dawn horse and ancestors of modern pigs and
primates - invaded
over the new land bridges.
In the water, meanwhile, vast regions lost their oxygen, killing
off half
the species of foraminifera in a massacre so devastating that
some
researchers refer to the result of the mass die-off as a
"Strangelove ocean"
- a nod to the classic film about nuclear annihilation.
But the assassin, many scientists now think, was not the kind of
fiery
asteroid that felled the dinosaurs: it was a great belch of
methane gas from
deep in the ocean. In the atmosphere, methane can trap the sun's
heat with
21 times the power of carbon dioxide. If even a small part of
frozen
deep-sea methane were to escape, computer models show, it could
easily
change the narrative of life.
And the trigger behind this ancient extinction, one leading
theory holds, is
a phenomenon with modern relevance: global warming. Then, as now,
the
earth's temperatures were slowly rising. Scientists think that
the warming
might have melted some of the methane, which would have caused
more warming
- setting off a chain reaction of disastrous methane releases.
"The fossil record shows that it's possible to have a
catastrophic change
that was triggered by slow warming," said Paul Olsen, a
Columbia University
geologist who has studied the web of emerging connections between
the
planet's geological and biological history. "The links to
the modern world
are obvious."
Olsen and other specialists emphasized that it's too early to
worry that our
cars, factories and power plants are poised to set off a methane
disaster,
because nobody has been able to prove precisely how it happened.
But,
whatever the cause, they said there is tantalizing evidence
methane has
exploded into the atmosphere at several points in earth's long
history and
that, at some point, it will likely happen again.
"The more we recognize it as happening in the past, the more
we should think
seriously about it happening in the present day," said
British scientist
Stephen Hesselbo, co-author of a July report in the journal
Nature that
provided evidence of a massive methane release 183 million years
ago.
Methane, frozen in fields of grayish-white ice crystals, has
attracted
increasing attention from scientists in range of disciplines, who
say that
the gas could play a much more dramatic role in our future than
anyone
imagined a decade ago. Mixed with sedimentary rock, as it is off
America's
East Coast, escaping methane can trigger roiling underwater
landslides, and
perhaps even tsunamis.
On the other hand, in it's purer form, found in parts of the Gulf
of Mexico,
methane could be a solution to the coming global energy shortage
when fossil
fuels such as oil run out.
"The amount of methane down there is enormous," said
Keith Kvenvolden, an
energy specialist with the United States Geological Survey in
Menlo Park,
California. Kvenvolden, who wrote a 1999 paper for the
Proceedings of the
National Academy of Sciences on the promise and perils of the
gas, estimated
that there are about 10,000 billion tons of carbon in methane -
twice the
known reserves of coal, oil and gas combined.
Methane, formed when one carbon atom joins four hydrogen atoms,
is a
familiar organic compound given off by bacteria as they consume
decaying
plant life. Invisible and scentless, the suffocating gas is one
of the
reasons miners would want to bring a canary with them. And the
gas's
incendiary tendencies are thought to have been inspiration for
stories of
"will-o-the-wisps," fairy-tale lights that danced in
swamps.
But, until three decades ago, nobody knew that the oceans held
deposits of
methane hydrate, as the crystals are called.
When dead organic materials settle to the ocean floor, it is set
upon by
bacteria that give off methane. Under the cold and crushing
pressures of the
depths, this methane forms hard crystals. Given millions of
years, the
process generates immense quantities of methane.
Scientists who study the planet's past climate then realized that
the
discovery of the deposits might explain sudden temperature jumps.
Researchers already knew that large amounts of organic carbon had
suddenly
appeared in the atmosphere, which would naturally trap heat and
drive global
temperatures up. But they could not identify any candidates for a
source.
With the methane discovery, they pieced together a scenario that
could bring
warm water to the ocean bottom and melt the methane ice.
It begins with gradual warming, caused perhaps by the volcanic
release of
carbon dioxide. This would increase the evaporation of sea water
at the
equator, leaving it saltier, and, thus, heavier. This heavy, warm
water
would then plunge down and start the cycle, explained Ellen
Thomas, a
research professor at Wesleyan University.
That would explain why a number of prominent extinctions are
associated with
volcanic activity, Olsen said.
There is also evidence, off the coast of Florida, of a
catastrophic
underwater landslide at precisely the time when all the changes
came 55
million years ago, according to Miriam Katz, a marine geologist
at Rutgers
University who published her findings last fall in the journal
Science.
Using a drill to draw up cores of earth from the sea floor, Katz
and her
colleagues found a level, sandwiched between neat sedimentary
layers, of
turbulent mixing, suggesting sudden changes in the landscape.
This layer
corresponded to a period of avalanches, with sections calving off
and
plunging down, said Katz, who is still researching the ways
methane might be
released from the sea bottom.
To those who try to map our climate future, methane is a
well-known
greenhouse gas. But most scientists agree that the threat of
major releases
is not a threat in the near term, certainly not in our lifetimes,
said
Kvenvolden.
It would take a major change in the ocean system to knock methane
hydrate
from the cold deep where it resides. And, other scientists added,
the only
times where methane has so far been implicated in major climate
shifts were
periods where the ocean waters were warmer than they are now.
But the threat of methane is a reminder that complex systems can
have
"threshold points," where dramatic change comes quickly
and without warning.
Already, some climatologists are worried that dumping carbon
dioxide into
the atmosphere could bring a sudden reversal in the deep ocean
currents,
also called the ocean "conveyor belt" - that carries
water from the equators
to the poles and back. Even without the danger of methane elease,
such a
shift could bring bitter winters to temperate climates.
"Looking at the planet's past provides natural experiments
that gives us
insights into processes that we wouldn't otherwise be able to
understand,"
said Olsen.
With the world's energy reserves rapidly depleting, methane
hydrate could
yet alter human history in this generation.
"Within twenty or thirty years, the era of permanent decline
in oil and gas
production will begin," said Roger Sassen, a research
geologist with Texas
A&M University. Sassen, who has done extensive work in the
Gulf of Mexico,
predicted that energy companies would be selling methane fuel
from the Gulf
within two decades.
Sassen, who has seen rising methane bubbles there click and pop
around
ships, said that the Gulf holds layers, some a kilometer thick,
of the ice
on its floor, visible from a submarine. He says the idea that
methane has
caused extinctions in the past has no more credibility than the
"Bermuda
Triangle literature."
Yet nobody has yet offered another convincing explanation for the
kinds of
carbon that suddenly appeared in the atmosphere.
Indeed, to others, it is a theory both compelling and humbling:
that
deposits which were only discovered in the last three decades
have played
such an important role in the drama of evolution. Paleontologists
have long
known that the dawning of the Eocene Epoch 55 million years ago
was the
beginning of the modern era of mammals - with humans to become
the most
successful of the new creatures - but they didn't know what
caused it.
"It's amazing that changes in the deep oceans could cause
the dispersal of
new mammals across the land," said William Clyde, a
specialist of mammalian
evolution at the University of New Hampshire. "It's amazing
there are all
these connections."
This story ran on page F1 of the Boston Globe on 10/17/2000.
© Copyright 2000 Globe Newspaper Company.
===========
(7) DON'T LAUGH: CLIMATOLOGISTS CLAIM COLD WINTERS CAUSED MASS
EXTINCTION 34
MYA
From The New York Times, 19 October 2000
http://www.nytimes.com/2000/10/19/science/science-extinction.html
Climate Change Led to Mass Extinction 34 Million Years Ago
By REUTERS
LONDON, Oct 18 - Severe climate changes 34 million years ago
wiped out 90
percent of all tiny sea creatures living along the Gulf Coast in
the United
States, scientists said on Wednesday.
Until now, researchers had been mystified by the largest
extinction since
the dinosaurs disappeared 65 million years ago, but new evidence
reported in
the science journal Nature shows it was caused by extremely cold
winters.
"We found that while the summer temperatures remained the
same, winter
temperatures dropped four degrees Celsius (seven degrees
Fahrenheit)," said
Linda Ivany of Syracuse University in New York.
"Palaeontologists had a suspicion that temperature had
something to do with
the extinction crisis because of the pattern of extinction but
there was no
quantitative demonstration of any kind of temperature
change," she added in
a telephone interview.
Ivany and scientists at the University of Michigan used a novel
technique to
study ancient climate changes by determining seasonal variations
in the
temperature of the water in the Gulf.
They analysed the chemical composition of fossilised samples of
minuscule
structures, called otoliths, in the ears of fish that lived in
the Gulf at
the time.
"The otoliths are made of calcium carbonate and they grow
accretively, just
like tree rings. They produce layer after layer after layer as
the fish
grows," said Ivany.
The chemical composition of that material changes according to
the
temperature of the water in which the fish live.
"This is the first time anyone has looked at seasonality as
a variable for
an extinction event across a geological time boundary,"
William Patterson,
who contributed to the research, said in a statement.
"We proved that winter temperatures caused the extinction.
Existing records
weren't able to resolve the change because the records are based
on
summertime growth. The fish survived the drop in winter
temperatures and
left a permanent record, while molluscs didn't make it."
Harry Elderfield of the University of Cambridge in England
described the
research as a fascinating example of high-resolution analysis of
climate
change.
"They show that although inferred temperatures did not
change...seasonality
did; summer temperatures remained the same but winters became
cooler," he
said.
Copyright 2000 The New York Times Company
===========
(8) NO EVIDENCE OF DEGLACIATION
From CO2 Science, 18 October 2000
http://www.co2science.org/journal/2000/v3n27c1.htm
The Need for Long-Term Glacier Mass Balance Data
Reference
Braithwaite, R.J. and Zhang, Y. 2000. Relationships between
interannual
variability of glacier mass balance and climate. Journal of
Glaciology 45:
456-462.
What was done
With respect to the ongoing quest to determine the nature and
magnitude of
long-term climate change, which typically focuses on detecting
presumed
anthropogenic-induced global warming, the authors note that
"any putative
trend of increasingly negative mass balance [of glaciers or ice
sheets] has
to be detected against the background of year-to-year
variations." In view
of this requirement, they explore the relationship between
long-term mass
balance and interannual variability in the totality of earth's
glaciers for
which such data exist.
What was learned
The authors begin by noting there are over 200 glaciers for which
mass
balance data exist for at least one year. When the
length-of-record
criterion is increased to five years, this number drops to 115;
and if both
winter and summer mass balances are required, the number drops to
79.
Furthermore, if ten years of record is used as a cutoff point,
only 42
glaciers qualify; and more stringent requirements result in much
lower
numbers. At the extreme record length of 50 years is the
Storglaciaren of
northern Sweden, which exhibited a negative mass balance of
little trend for
the first 15 years of record but which then began to trend
upward, actually
becoming positive over about the last decade.
Working with various sets of these glaciers, the authors develop
relationships that allow them to calculate how long a period of
mass balance
measurements would be required to determine whether or not the
Greenland ice
sheet was in a state of flux or equilibrium. They conclude that
"the ice
sheet can thicken or thin by several meters over 20-30 years
without giving
statistically significant evidence of non-zero balance under
present
climate."
What it means
In the words of the authors, "one of the most important
problems for
mass-balance glaciology, after more than 50 years of hard work,
is the sad
fact that many glacierized regions of the world remain unsampled,
or only
poorly sampled," suggesting that we really know very little
about the true
state of balance of most of the world's glaciers. As for the
Greenland ice
sheet, they conclude that it might "have to be monitored
over many decades
to detect unambiguous evidence of either thinning, due to
increased melting,
or thickening, due to increased accumulation."
The moral of the story? Don't hold your breath waiting for a
definitive
answer about the state of the Greenland ice sheet. And without a
definitive
answer, don't jump to conclusions; you'll only be speculating. In
the case
of the glacier with the longest mass balance on record, however,
we need not
speculate. It is clear there has been a significant upward trend
in its mass
balance state over the past 30-40 years and that it has been in a
mass
accumulation state for at least the past decade.
Reviewed 18 October 2000
================
(9) 6000 YEARS OF SEA LEVEL CHANGE IN THE SOUTHERN HEMISPHERE
From CO2 Science, 18 October 2000
http://www.co2science.org/journal/2000/v3n27c4.htm
References
Baker, R.G.V. and Haworth, R.J. 2000. Smooth or oscillating late
Holocene
sea-level curve? Evidence from cross-regional statistical
regressions of
fixed biological indicators. Marine Geology 163: 353-365.
Baker, R.G.V. and Haworth, R.J. 2000. Smooth or oscillating late
Holocene
sea-level curve? Evidence from the palaeo-zoology of fixed
biological
indicators in east Australia and beyond. Marine Geology 163:
367-386.
What was done
The authors present substantial evidence that sea-level, as
measured over
large portions of the Southern Hemisphere, has declined
significantly since
approximately 6,000 years ago. But has the journey been smooth or
oscillatory? In attempting to answer this question, they review
data,
including much of their own, obtained from a number of different
places in
the non-glaciated, tectonically-stable regions of the Southern
Hemisphere.
What was learned
For the period from 6,000 to 600 years before present, the
authors
demonstrate that an oscillatory mode of sea-level decline is just
as likely
to have occurred, in terms of "statistical
justification" based on the
available data, as a smooth decline.
What it means
In the words of the authors, "whether or not sea level has
been subject to
low-amplitude fluctuations during the late Holocene (the last ~
6000 years)
is a subject that has taken on increased importance in view of
claims of
possible sea-level rise associated with human-induced global
warming." If,
for example, sea-level has oscillated somewhat over this period
(the authors
say it could have had an oscillatory amplitude of one meter or
more!), it is
possible the sea-level's current rising mode may be nothing more
than a
small portion of a natural oscillation having nothing to do with
the ongoing
rise in the air's CO2 content. The authors' finding that this
type of
sea-level behavior is just as likely to be true as not thus casts
a pall of
suspicion over climate alarmist claims that the continued burning
of fossil
fuels will lead to the inundation of low-lying coastal areas and
islands.
In light of these observations, we can draw some important
conclusions about
the way we should approach the future. First, there are those who
claim the
continued burning of fossil fuels is nigh unto criminal, because
of what
they claim this course of action will ultimately mean for coastal
lowlands
and islands, i.e., their submergence beneath the sea. But
if they are wrong
about the cause of the warming, which they believe to be the
cause of the
sea-level rise - and this study says there's a fifty-fifty chance
they are
wrong on the last point alone - the actions they would have us
take could be
viewed as criminal; for reducing CO2 emissions would give the
inhabitants of
the threatened regions a false hope of security that would
ultimately be
dashed by the inexorable natural rising of the sea, and at a time
when it
may be too late to do anything about it, especially if the global
economy
suffers irreparable harm from misguided energy policies that
could leave it
too weak to help avert the human tragedy that would likely
accompany a
sea-level rise of the magnitude the data of these studies suggest
is
possible.
This being the case, the Precautionary Principle would seem to
suggest that
the nations of the world should begin preparing for a sea-level
rise of
precisely the type the climate alarmists are ranting and raving
about, not
in terms of trying to avert it, as they propound - especially by
incredibly
disruptive measures that could well have absolutely no effect
upon it - but
in terms of adapting to it in some way, hopefully in advance and
not in
retrospect. To do anything else --and especially something that
has no
impact whatsoever upon the problem, costs us dearly in terms of
human and
natural resources, and is actually detrimental to our ability to
feed
ourselves (remember that CO2 is a tremendous aerial fertilizer)--
is more
than just illogical; it is, as they say, criminal.
Reviewed 18 October 2000
Copyright © 2000. Center for the Study of Carbon Dioxide
and Global Change
============================
* LETTERS TO THE MODERATOR *
============================
(10) SPACE EXPLORATION: THE CHINESE CENTURY?
From Michael Martin-Smith <martin@miff.demon.co.uk>
Dear Benny,
Bob Kobres points out the possible material benefits of space
development to
our civilzation en route to dealing with the threat from NEO
impacts. For
those who despair that the West will ever accept such a radical
view of our
future, some hope for the species follows below.
It is becoming likely that there will, after all, be humans on
the Moon on
or before Apollo's 50th anniversary (2019 AD); fortunately - or
unfortunately according to taste - these will most likely be
Chinese,
launched from Jiu Qian. An interesting question is; "How
many
Americans/Westerners will view this with equanimity, and how many
will blame
their leaders and PC opinion formers for having allowed their
nation to follow the
historic fate of Admiral Cheng-Po's voyages under the Ming
Dynasty?"
The West should reflect that the 21st century has been called by
some
futurologists "the Chinese century". One reason for
this will be a growing
realization by China (not least Messrs Jiang Zemin and Zhu
Rong-ji)- of the
strategic importance of space exploration, exploitation, and - in
due time -
settlement.
The future justly belongs to the far-sighted and adventurous.
--
Dr Michael Martin-Smith, author of "Man, Medicine and
Space" to appear in
coming weeks (hopefully!) as a publication available by
mail/internet order
from www.iUniverse.com -
the 21st century publisher
MODERATOR'S NOTE: Nothing against futurologists, Michael. But the
claim that
the 21st century will be a "Chinese century" because of
their expanding
space programme reminds me of similar predictions made by the
same people,
not too long ago, about the coming "Soviet century."
Let's face it; as long
as China remains a brutal dictatorship that suppresses and
persecutes
millions of people for their political views and religious
beliefs, and
threatens other countries with aggression and invasion, nobody in
their
right mind will see the Chinese space programme as a blessing for
a healthy
development of our global village. The 20th century experience
with
totalitarian regimes (responsible for the killing of some 100
million
people) should have taught us not to fall for their grandiose
programmes -
be they giant Olympic stadia or propagandistic space
missions. On the other
hand, if China's young democracy movement were to succeed, and I
have little
doubt that freedom and democracy will be established eventually,
China would
be more than welcome into the family of free nations. Until such
time, we
should advocate human rights and political freedom rather than
being blinded
by Chinese space developments.
BJP
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