PLEASE NOTE:


*

CCNet, 64/2000 -  5 June 2000
------------------------------


     "Armageddon - triggered by an asteroid hurtling into our planet -
     is a genuine risk. Now some scientists are pressing the European
     Space Agency (Esa) to construct a satellite called Gaia which
     could pinpoint errant chunks of rock that threaten Earth. The
     probe - the most accurate telescope ever built - would track
     objects a kilometre or more in diameter, allowing scientists to
     predict their path years before their collision with our planet.
     Rocket-born nuclear bombs could then be launched to nudge them
     from their deadly paths."
            -- Robin McKie, The Observer


(1) ANOTHER NEO-CASTLE IN THE AIR: EUROPE PLANS TO SAVE THE
    WORLD WITH $500m SPACE PROBE
    The Observer, 28 May 2000

(2) PRIMITIVE METEORITES SHED NEW LIGHT ON EARTH'S ORIGIN
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(3) DIAMONDS FROM IMPACTS & UPDATE ON NANOBES
    Michael Paine <mpaine@tpgi.com.au>

(4) EXTINCT COMETS OR D-TYPE ASTEROIDS?
    M.D. Hicks et al., CALTECH,JET PROP LAB

(5) ORBITAL EVOLUTION OF ASTEROIDS DURING DEPLETION OF THE
    SOLAR NEBULA
    M. Nagasawa et al., TOKYO INST TECHNOL

(6) SURVEY OF TRANSIENT CO-ORBITALS OF TERRESTRIAL PLANETS
    A.A. Christou, UNIVERSITY OF LONDON

(7) ESA'S LONG-TERM SPACE POLICY
    W. Seboldt et al., DLR

(8) CCNet POST ON GLOBAL WARMING
    Steve Drury <s.a.drury@open.ac.uk>

(9) AMAZON FORESTS
    Jeremy Tatum <UNIVERSE@uvvm.UVic.CA>

(10) AND FINALLY: ALTERNATIVE METEORITE DEFENSE
     Scott Manley <spm@star.arm.ac.uk>

==================
(1) ANOTHER NEO-CASTLE IN THE AIR: EUROPE PLANS TO SAVE THE
    WORLD WITH $500m SPACE PROBE

From The Observer, 28 May 2000
http://www.observer.co.uk/uk_news/story/0,6903,319399,00.html

ASTEROID TRACKERS PLAN TO AVERT ARMAGEDDON:
Space probe will allow detection and deflection of rocks hurtling to
Earth, reports Robin McKie

Sunday May 28, 2000

One did for the dinosaurs. Another flattened a large part of Siberia 90
years ago. And one day Britain - not to mention Europe and the rest of
the world - may suffer a similar fate.

Armageddon - triggered by an asteroid hurtling into our planet - is a
genuine risk. Now some scientists are pressing the European Space
Agency (Esa) to construct a satellite called Gaia which could pinpoint
errant chunks of rock that threaten Earth.

The probe - the most accurate telescope ever built - would track
objects a kilometre or more in diameter, allowing scientists to predict
their path years before their collision with our planet. Rocket-born
nuclear bombs could then be launched to nudge them from their deadly
paths.

"Gaia will carry a set of giant video cameras that will take colour,
stereoscopic images of more than a billion stars, galaxies and other
objects," said one of the project's leaders, Dr Jerry Gilmore, of
Cambridge's Institute of Astronomy.

"Essentially we are going to take a 3-D movie of the Milky Way. We will
be able to construct a map of the heavens of such unsurpassed accuracy
that we will be able to solve a host of major astronomical problems:
the origin of the Milky Way, the shape of the universe - and the
likelihood of Earth being battered by an asteroid."

Earth's prospects of being destroyed by a large chunk of planetary
masonry are currently being investigated by a government task force set
up by Lord Sainsbury. The three-man team - made up of senior science
administrator Harry Atkinson, environmentalist Sir Crispin Tickell and
Professor David Williams of University College, London -  will report
in a few weeks.

The team believes there is a real risk, albeit a small one, that Earth
will suffer a major asteroid impact, and that more international
co-operation is needed to track the most dangerous objects. It has been
calculated - by studying the rate at which lunar craters were formed by
crashing meteorites and asteroids - that Earth will be struck by an
object greater than a kilometre in diameter every 500,000 years.

Nasa recently established a Near Earth Object programme which
has tracked 400 of the estimated 1,000 kilometre-plus asteroids in our
part of the solar system.

"None are likely to strike our planet in the foreseeable future," said
Donald Yeomans, the programme's chief. "However, there are hundreds out
there that we just don't know about."

Scientists say asteroids greater than a kilometre in diameter will
cause global devastation. "They will throw up vast clouds of dust that
will blot out the sun, pour down acid rain, freeze the planet, and
destroy all civilisations," said Yeomans.

Nasa's survey programme is restricted to ground-based telescopes and
radio observatories. Gaia's telescopes would detect an object the size
of a shirt button on the Moon. 

To achieve such precision the probe would have to have virtually
no moving parts with every component maintained at a precise
temperature to ensure no thermal buckling or movement.

Due to be launched by an Ariane 5 rocket in 2009, Gaia is short-listed
for 350 million of Esa funding, but is in competition with a proposed
probe to Mercury. Gaia is the favourite to gain approval in September.

"Gaia will carry out all sorts of different kinds of astronomy," said
Gilmore.

"However, the real bonus is that it could save us from the same fate as
that suffered by the dinosaurs."

Pinpointing an asteroid decades before it strikes Earth is one thing.
Doing something about it is quite another.

Blowing it up with a nuclear bomb - as Bruce Willis did in the film
Armageddon - would do more damage than good, say scientists, for the
blast would probably pepper Earth with cosmic shrapnel.

"However, nudging it off its trajectory with an A-bomb explosion, so
that it missed us completely, might well work," said Yeomans.

Copyright 2000, The Observer

================
(2) PRIMITIVE METEORITES SHED NEW LIGHT ON EARTH'S ORIGIN

From Andrew Yee <ayee@nova.astro.utoronto.ca>

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

Contact: Nancy Ross-Flanigan
Phone: (734) 647-1853
E-mail: rossflan@umich.edu

News Release: May 31, 2000

New analysis sheds light on Earth's origins

ANN ARBOR -- A new analytical method has resolved a longstanding
scientific debate on the origins of Earth and the moon, researchers
from the University of Michigan and the Swiss Federal Institute of
Technology report in the June 2 issue of Science.

The debate focuses on a group of primitive meteorites called enstatite
chondrites. Because the ratio of different forms (isotopes) of oxygen
in materials from Earth and the moon matches that of enstatite
chondrites -- but no other meteorites -- it had been proposed that
Earth formed from materials much like the enstatite chondrites. These
materials were thought to have come from a very localized region of the
solar system. But other studies, such as simulations of how the planets
formed, have cast doubt on the theory.

Der-Chuen Lee, a research fellow in the U-M Department of Geological
Sciences, and Prof. Alex N. Halliday of the Swiss Federal Institute of
Technology's Institute for Isotope Geology and Mineral Resources in
Zurich, Switzerland, used a recently developed method that compares
extremely small differences in tungsten isotope ratios. If Earth and
the moon did form from material similar to enstatite chondrites, their
tungsten isotopic compositions, as well as their oxygen isotopic
compositions, should match.

"To our surprise, enstatite chondrites do not have the same tungsten
isotopic compositions as Earth," nor do they match any other meteorites
that have been tested, says Lee. Based on this evidence, "we propose
for the first time with much certainty that there is no direct genetic
relationship between Earth and enstatite chrondrites." Instead, the
data support the alternative idea that planets, as they formed, received
materials from very broad regions of the solar system.

================
(3) DIAMONDS FROM IMPACTS & UPDATE ON NANOBES

From Michael Paine <mpaine@tpgi.com.au>

Dear Benny,

Today's Science Show on Australian ABC Radio had two items of interest
to CCNet.

Nanobes
Dr Philippa Uwins from Queensland University gave an update on 'nanobe'
research. In brief the research over the past year has strengthened the
view that these tiny objects, some less than 100 nanometers in length,
are living organisms. They are turning up in other places, now that
researchers know what to look for. She is collaborating with NASA's Ames
Research group on the implications for extraterrestrial life (and the
famous martian meteorite ALH84001).
A summary of the show is at
http://www.abc.net.au/rn/science/ss/stories/s132235.htm

Diamonds from impacts
Dr Rob Hough from Western Australian Museum discussed his successful
search for tiny diamonds formed from carbon in the 'target' rocks during
meteor impacts. He is interested in the recently identified Woodleigh
Structure in Western Australia.
http://www.abc.net.au/rn/science/ss/stories/s132232.htm

Transcripts for both interviews should be available in a few weeks.

regards
Michael Paine

==========
(4) EXTINCT COMETS OR D-TYPE ASTEROIDS?

M.D. Hicks*), B.J. Buratti, R.L. Newburn, D.L. Rabinowitz: Physical
observations of 1996 PW and 1997 SE5: Extinct comets or D-type
asteroids? ICARUS, 2000, Vol.143, No.2, pp.354-359

*) CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 183-501,PASADENA,CA,91109

The minor planets 1996 PW and 1997 SE5 are two of the few known
asteroids with orbital elements typical of long-period and
Jupiter-family comets and as such represent strong candidates for
extinct cometary nuclei. We obtained filter photometry of 1996 PW and
filter photometry and medium-resolution CCD spectroscopy of 1997 SE5
during their discovery apparitions. We also observed a suite of D-type
asteroids as possible spectral analogs of cometary nuclei. Both 1996 PW
and 1997 SE5 have moderately red, featureless spectra typical of the
D-type asteroids, cometary nuclei, and other extinct cometary
candidates. The photometry for 1997 SE5 was fit by a triple-peaked
lightcurve with a period of 9.050 +/- 0.005 h and an amplitude of 0.4
magnitude, suggesting a relatively complex and elongated shape. With
this work, 1997 SE5 and 1996 PW join the ranks of 3552 Don Quixote and
944 Hildago as established candidates for extinct comet nuclei. (C)
2000 Academic Press.

=================
(5) ORBITAL EVOLUTION OF ASTEROIDS DURING DEPLETION OF THE
    SOLAR NEBULA

M. Nagasawa*), H. Tanaka, S. Ida: Orbital evolution of asteroids during
depletion of the solar nebula. ASTRONOMICAL JOURNAL, 2000, Vol.119,
No.3, pp.1480-1497

*) TOKYO INST TECHNOL,DEPT EARTH & PLANETARY SCI,MEGURO KU,TOKYO
   1528551,JAPAN

The pumping-up of inclinations and eccentricities caused by sweeping
secular resonances in the asteroid belt is studied through numerical
orbital integration and linear analysis. The present asteroids have
large mean eccentricities and inclinations that cannot be explained by
planetary perturbations alone. Sweeping of secular resonances
associated with the depletion of the primitive solar nebula has been
proposed for the origin of asteroids' orbits (e.g., by Ward, Colombo,
and Franklin in 1976). We performed three-dimensional orbital
integrations of asteroids under gravitational forces by Jupiter,
Saturn, and the solar nebula. The asteroids' motions are also affected
by hydrodynamic gas drag. We consider three types of nebula depletion
models: (1) the uniform depletion model, in which the nebula density
decreases exponentially with time and uniformly throughout the nebula;
(3) the inside-out depletion model, in which nebula gas is depleted
from the inside region; (3) the gap-opening model, in which a gap
centered at Jupiter gradually expands. Previous studies have
concentrated on the two-dimensional uniform depletion model. Our
simulation shows that inclinations of asteroids are not pumped up
enough in the first model to account for the observed magnitude.
Moreover, most asteroids spiral into the Sun by gas drag if the
depletion timescale is longer than 10(5) yr because pumped-up
eccentricity induces strong gas drag. On the other hand, in the second
and third models, inclinations are pumped up. Our linear analysis shows
that the nonuniform depletion model is essential for the secular
resonances pumping up inclination to sweep in the asteroid belt. In the
case of the inside-out depletion model, both eccentricity and
inclination are pumped up enough to be consistent with the observed
magnitude in the entire asteroid belt, if the nebula depletion
timescale (which is the time required for the nebula edge to migrate by
the distance of 5 AU) is longer than 3 x 10(5) yr. Furthermore, since
secular resonances pass after nebula gas has already been depleted in
the passing region, gas drag does not damp the pumped-up eccentricities
and inclinations and the semimajor axes of the asteroids. Therefore,
the resultant eccentricity and inclination in the inside-out depletion
model are consistent with observed ones for the nebula depletion time
inferred from observed T Tauri stars (10(6)-10(7) yr). Our gap-opening
model shows similar results, although eccentricity and inclination are
slightly smaller in the outer asteroid belt region. The essentially
required condition to pump up both eccentricity and inclination highly
enough in the asteroid region is that the nebula edge moves outward
from 5 to 10 AU. The gap formation caused by Jupiter's tidal
perturbations may be similar to our inside-out or gap-opening models,
inside 10 AU. Therefore, it would be responsible for the high
eccentricities and inclinations in the asteroid belt. Copyright 2000,
Institute for Scientific Information Inc.

==============
(6) SURVEY OF TRANSIENT CO-ORBITALS OF TERRESTRIAL PLANETS

A.A. Christou: A numerical survey of transient co-orbitals of the
terrestrial planets. ICARUS, 2000, Vol.144, No.1, pp.1-20

UNIVERSITY OF LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,ASTRON
UNIT,MILE END RD,LONDON E1 4NS,ENGLAND

We have investigated numerically the evolution of near-Earth asteroids
(3753) Cruithne, (3362) Khufu, 1989 VA, (10563) 1993 WD, and 1994 TF2
that enter the coorbital regions of the Earth or Venus. We show that
the coorbital libration modes identified in F. Namouni (1999, Icarus
137, 293-314) and F. Namouni et al. (1999, Phys. Rev. Lett. 83,
2506-2509) are strong enough to survive tens of thousands of years
under planetary perturbations in the Solar System. We give a detailed
analysis of the nature of libration modes as functions of the argument
of perihelion. The effects of close approaches with the coorbiting
planet as well as neighboring planets are characterized. Based on these
results, we argue for a steady-state flux of objects temporarily
captured in coorbital configurations with the planets. (C) 2000
Academic Press.

===========
(7) ESA'S LONG-TERM SPACE POLICY

W. Seboldt*), M. Reichert, N. Hanowski, M. Novara: A review of the
long-term options for space exploration and utilisation. ESA
BULLETIN-EUROPEAN SPACE AGENCY, 2000, No.101, pp.31-39

*) DLR,INST WELTRAUMSENSORIK & PLANETENERKUNDUNG,COLOGNE,GERMANY

ESA's Long-Term Space Policy Committee (LSPC) has underlined the need
for Europe to think ahead and establish a vision for its future space
activities with a 30-year horizon. The goal is to identify promising
opportunities, and to establish in Europe the key capabilities and
critical technologies required for the exploration and utilisation of
space over the next three decades. Studies and discussions have focused
on the Earth-Moon system, Mars, near-Earth asteroids and comets.
Scientific motivations are an important aspect in all potential space
exploration and utilisation activities, but economic, commercial and
technological issues are paramount in addressing central questions such
as the preparatory efforts required and  the potential benefits.
Copyright 2000, Institute for Scientific Information Inc.

=============================
* LETTERS TO THE MODERATOR *
=============================

(8) CCNet POST ON GLOBAL WARMING

From Steve Drury <s.a.drury@open.ac.uk>

Your last contributor on the global warming debate (CCNet, 2 June 2000)
suggests that current evidence for global warming is part of the normal
interglacial process. The Holocene, as the latest interglacial is
called, has lasted for about 10 500 years, with a slowly changing
climatic record, and that might suggest support for the 'natural
progression' view of warming.

However, results from an ice core through the Antarctic ice sheet
reveals lots of information about the course of the three previous
glacial-interglacial cycles, each around 100 000 years long. One of the
conclusions is that the Holocene is unusually long compared with the
last three, by up to several thousand years.

Refer to Petit et al., 1999. Climate and atmospheric history of the
past 420 000 years from the Vostok ice core, Antarctica.  Nature, vol
399 (3 June 1999), p 429-435

Of course, we should hope for the Holocene to last indefinitely, for
the slightest climate shift will disrupt the agricultural patterns on
which billions of people depend. Because the broad fluctuations in
global climate for the last 2.7 million years track changes in the
amount of solar energy received in the northern summer, as a result of
regular changes in the Earths orbit and axis of rotation induced by
gravitational influences from the rest of the Solar System, left to
itself the Earth cannot escape decline to another glacial epoch in the
near future.  For this reason, there are many who accept anthropogenic
warming, yet hope that it will be a potential saviour from descent back
into the colder and globally drier conditions, with much reduced
biological productivity, that every glacial period brings on.

That too is a dangerous view, because one of the most important
controls on rapid climate changes seen in ice-core records (as quick as
a few decades if not years), for the North Atlantic at least, and
possibly the Earth as a whole, is the way that cold, dense brine sinks
around Iceland to draw in the warming influence of the Gulf Stream. 
This formation of a deep-water flow seems highly dependent on formation
of winter sea ice, that leaves behind a more salty and dense residue
that sinks to replenish the deep circulation - sea-ice is pure water. 
Global warming, perversely, would reduce winter freezing of the sea in
this crucial area, perhaps shutting down the deep flow and its warm
counter current at the surface.  That is, warming rapidly induces
cooling at high latitudes. That is a good way to trigger prematurely
the onset of the next glaciation!

Steve Drury

===============
(9) AMAZON FORESTS

From Jeremy Tatum <UNIVERSE@uvvm.UVic.CA>

Dear Benny:

I am not sure what articles on Brazilian forests have to do with the
usual peisergram topics, but the Patrick Moore you quote as one of the
"world's top eco-scientists" is a well-known and highly outspoken
propagandist for the Canadian forestry industry who has made a career
out of attacking the views of anyone with an environmental conscience. 
For you to publish this propaganda under the heading "Another eco scare
exposed as myth", which I presume was your own wording, severely
damages your own scienntific credibility.

Jeremy Tatum

================
(10) AND FINALLY: ALTERNATIVE METEORITE DEFENSE

From Scott Manley <spm@star.arm.ac.uk>

Here's an alternative interpretation of the phrase 'Meteorite Defence'
- billed as the oldest knives in the solar system. Either that or it's
the Prequel to 'Nemesis' using a meteorite as a weapon.....

http://home.HiWAAY.net/~dfronfld/

Midnight folding knife (click for larger image)

This folder, titled "Midnight", features a  hand forged damascus blade
in the san-mai style. It consists of 80 alternating layers of nickel
and 1085 steel laminated on either side of a 5160 steel core. The
liners are titanium, and both the blade and liners are extensively
file worked. (Click on image for larger view)

The bolsters are made from Gibeon nickel-iron meteorite which is acid
etched to reveal the beautiful widmanstatten pattern seen only in
meteorites. Widmanstatten patterns develop during the slow cooling of
the iron core of a planetoid (asteroid). The handles are diamond cut
from Renfrow stony meteorite. This meteorite exhibits a black stone
matrix flecked with bright nickel inclusions, reminiscent of a starry
sky. The spine and thumb-bob are inlayed with Albin stony-iron
meteorite. This rare and fragile meteorite forms as molten
nickel-iron flows around emerald green olivine crystals.

Meteorites are more rare than any other material on earth. In many
cases, the total known weight of a  meteorite is less than a
kilogram.   Some meteorites have constituents that predate the
formation of our solar system. A few meteorites contain star dust,
ejected from super novas billions of years before our solar system
formed.  Some contain amino acids, the building blocks of life.  And
some, may even include evidence of life on Mars. This is truly an
incomparable opportunity to own a fragment of space, crafted  to
please the eye and hand.

----------------------------------------
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CCCMENU CCC for 2000

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