PLEASE NOTE:
*
CCNet, 29 Sepetmber 1999
------------------------
POEM OF THE DAY
The Shifting Earth
By Malcolm Miller <stellar2@actonline.com.au>
The world looks flat to most of us, and
as well we think
that it's unchanging, too, its familiar
features and its climate
there forever in the people's
memory. The rocks, the rivers,
mountains and seas unchanged since 'time
immemorial',
ordained by God to be for evermore to be
our home.
'Not so' these upstart scientists say,
the ancient shorelines
and retreating glaciers only a small
part of those clear signs
laid out for us to read.Faith in the
constancy of Earth is natural,
but those who've learned to see and
understand the unambiguous
book of nature now know we live on
shifting ground.
As our numbers grow our vulnerability
increases,
so earthquake, ice, impact and flood
will target more of us,
unless we learn to develop survival
skills to ensure our footing
on this impermanent surface of a rocky
sphere, with strategies
to minimise the harm from shaking ground
or flaming skies.
MM 29.9.99
(1) HAS EARTH BEEN WATERY PLANET RIGHT FROM THE START?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(2) INTERPLANETARY EVOLUTION OF HUMAN CULTURE & COMMUNICATION
Larry Klaes <lklaes@bbn.com>
(3) ANOTHER ICE-MAKING MACHINE IN THE SOLAR SYSTEM?
ESA <sciweb@estec.esa.nl>
(4) NEW PLANET OR NEW KBO?
BBC News Online, 28 September 1999
================
(1) HAS EARTH BEEN WATERY PLANET RIGHT FROM THE START?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[http://helix.nature.com/nsu/990930/990930-4.html]
Monday, September 27, 1999
Water bath
By PHILIP BALL
Prevailing opinion has it that the oceans came from space after
the
Earth was formed 4.6 billion years ago. It has been thought that
the
impact of icy bodies -- comets or debris left over from the
formation
of the planets -- on the early Earth deposited the water that now
fills
the ocean basins. But an alternative idea is that the material
that
went into the formation of our planet was already wet.
All the planets formed from clumps of matter that condensed
within the
cloud of gas and dust surrounding the new-born Sun. Collisions
between
these clumps were constantly happening throughout the early Solar
System, and the debris that resulted then stuck together under
its own
gravity. The lumps within the inner Solar System may have been
dry and
rocky, with the volatile constituents -- the gases and liquids in
the
atmospheres of Venus, Earth and Mars -- added by later
collisions.
But did it have to be this way, or could the initial clumps have
themselves contained water? If so, it seems likely that most of
this
water would have been dissolved in a pole-to-pole ocean of molten
rock
-- magma -- when the Earth was still young. Such a magma ocean is
expected to have resulted from the massive collision widely
believed to
have split off the material that formed the Moon. As the magma
cooled
and froze, the water would then have come steaming out into the
atmosphere, later to condense into oceans.
As the Earth cooled, it separated into an iron-rich core and a
rocky
mantle -- like slag separating from the molten metal in an iron
smelting furnace. Other metals similar to iron, such as cobalt,
nickel
and tungsten, would have dissolved to different extents in the
magma
ocean and the molten iron below. Geophysicists can account for
the
known distribution of such metals between the present core and
mantle
based on the way that they partition between iron and molten, dry
rock
-- but how would water affect this picture?
Kevin Righter and Michael Drake from the University of Arizona
have now
measured this partitioning behaviour, with water present, at the
high
temperatures and pressures appropriate to the juncture between an
iron
core and a magma ocean. They find that small amounts of water, as
postulated for a "wet" accretion of the Earth, do not
undermine the
existing explanation for the distribution of metals between core
and
mantle.
What is more, they say, water present from the very beginning of
Earth's history can help to explain why there is so much iron
oxide in
the mantle today: the oxide is formed by the reaction of water
with hot
iron. It is not easy otherwise to account for how the iron oxide
got
there.
So the new measurements, reported in the journal Earth and
Planetary
Science Letters (September), lend support to the idea that the
Earth
has been a watery planet right from the start.
© Macmillan Magazines Ltd 1999 - NATURE NEWS SERVICE
=================
(2) INTERPLANETARY EVOLUTION OF HUMAN CULTURE & COMMUNICATION
From Larry Klaes <lklaes@bbn.com>
INTERPLANETARY INTERNET RESEARCH SEMINAR
Friday, 12 November 1999
09:00 - 12:15
Van Munching Hall, Marriott Room
University of Maryland, College Park
For travel directions to Van Munching Hall, please follow this
link:
http://www.inform.umd.edu/CampusInfo/Facilities/Buildings/VMH/
Cost: approx. $16 at the door
Over the last thirty years, the terrestrial Internet has grown
from a
few computers that were networked in a prototype laboratory
environment
into a vast deployed system that is an indispensable component of
the
present and future global economy. Key to its exponential growth
has
been its underpinning of flexible and "open" standard
communications
protocols (the TCP/IP suite) that permit diverse applications to
instantaneously exchange information. During the coming thirty
years,
the terrestrial Internet will experience growth and evolution in
ways
which are almost unimaginable. Its communications infrastructure
will
experience huge increases in capacity, while a large varied of
"untethered", wireless-based applications will emerge
as plug-ins to
the edges of its fiber/copper communications backbone. In the
process,
the Internet's communications protocols will evolve to meet new
challenges.
The next thirty years will also see the need to expand the
Internet so
that it can serve the communications needs of the progressive
expansion
of human intelligence into space. The "InterPlaNetary
Internet"
initiative has therefore been initiated by DARPA and NASA to
chart a
course whereby the Internet may move gracefully off-planet.
The
purpose of this seminar is to introduce a candidate
InterPlanetary
Internet (IPN) architecture to the research community and to
solicit
feedback with respect to its unique challenges. To facilitate the
establishment of an interactive dialog with (and within) the
community,
the candidate architecture will be presented as a whole, followed
by
discussion focused in four key areas, each punctuated by
opportunities
for questions and discussion. The preliminary agenda for this
seminar
is presented below:
For further information, please contact:
M. Scott Corson
(corson@isr.umd.edu)
301-405-6630
Center for Satellite and Hybrid Communication Networks
Institute for Systems Research
University of Maryland, College Park
==================
ANOTHER ICE-MAKING MACHINE IN THE SOLAR SYSTEM?
From ESA <sciweb@estec.esa.nl>
http://sci.esa.int/newsitem.cfm?TypeID=1&ContentID=6891&Storytype=18
Uranus and Neptune are very different from Jupiter and Saturn,
according to examinations of the giant planets by ESA's infrared
space
telescope, ISO. Jupiter and Saturn are mainly balls of gas but
the more
distant Uranus and Neptune contain relatively large cores of ice.
This
difference is confirmed by French and German astronomers who used
ISO
to measure heavy hydrogen in the planet's atmospheres. Although
the
result fits well with current ideas about planetary origins, it
casts
doubt on the part played by comets.
Water ice and other types of ices, including methane, were a raw
material during the birth of the giant planets. Little of it
survived
close to the Sun, where the Earth and other rocky planets formed.
In
cooler regions the ices supposedly made quite large planets, with
gravity strong enough to bind gases into the thick atmospheres
that
make them giants. The accompanying picture from Stockholm
University
illustrates a theoretical study of the building of a giant planet
in
the young Solar System.
Although ISO could not see the icy cores, now hidden deep inside
the
giant planets, it found a fingerprint of ice - an excess of heavy
atoms
in the hydrogen gas of their atmospheres. Due to chemical
reactions at
low temperatures ices possess an excess of heavy hydrogen, or
deuterium. Some of this deuterium has found its way into the
atmospheres of the planets, where ISO's short wavelength
spectrometer
(SWS) detected it.
"We have the first accurate values of deuterium's abundance
in Uranus
and Neptune," says Helmut Feuchtgruber of Garching, Germany.
"And we
can compare them with those in Jupiter and Saturn, obtained with
the
same instrument. This enables us to draw conclusions about the
deep
interior of the giant planets, which are completely hidden from
view".
Uranus and Neptune have three times more deuterium in their
hydrogen
gas than Jupiter or Saturn. This is consistent with ices making
up more
than half of their mass, whereas in Jupiter and Saturn ices
represent a
much smaller part of the total - too small to make any noticeable
enrichment of the deuterium in the atmospheres. The four giant
planets
may have started with similar icy cores, each roughly ten times
the
mass of the Earth. The differences then arose from the
availability of
gases to fill their atmospheres, with Jupiter gathering about
forty
times more gas than Uranus or Neptune did.
The ISO results confirm in broad outline the present theories of
planetary formation, but they contradict a popular belief that
the ice
came from comets like those still seen today. Comets are icy
survivors
from the origin of the Solar System, so it might be easy to
imagine
congregations of comets building the icy cores of the giant
planets.
But the proportion of deuterium in comets is five times greater
than in
Uranus or Neptune, and the ISO scientists calculate that the
cores were
made from ice containing much less deuterium. So in the swirling
cloud
of gas and dust around the Sun, from which the planets were born,
theorists have to imagine a different ice-making machine.
An extensive study of the outer planets, using ISO observations,
is led
by Thèrese Encrenaz and Emmanuel Lellouch of the Observatoire de
Paris-Meudon and Helmut Feuchtgruber of the Max-Planck-Institut
für
Extraterrestrische Physik. A full account of results so far has
been
included in a new book from ESA, "The Universe as Seen by
ISO"
(ESA SP-427).
A video clip on this story will be released at 13:00 UTC today,
29
September on Tracker 2000 - the multimedia service from ESA
science
at: http://sci.esa.int/tracker2000/index.htm
The video can be ordered via an on-line form.
Footnote about ISO
The European Space Agency's infrared space telescope, ISO,
operated
from November 1995 till May 1998, almost a year longer than
expected.
As an unprecedented observatory for infrared astronomy, able to
examine
cool and hidden places in the Universe, ISO successfully made
nearly 30
000 scientific observations.
For more information please contact:
ESA Public Relations Division:
Tel: +33(0)1.53.69.71.55
Fax: +33(0)1.53.69.76.90
Martin F. Kessler (ISO Project Scientist):
Tel: +34 918131254
mkessler@iso.vilspa.esa.es
===================
(4) NEW PLANET OR NEW KBO?
From the BBC News Online, 28 September 1999
http://news.bbc.co.uk/hi/english/sci/tech/newsid_460000/460095.stm
Old spacecraft makes surprise discovery
By BBC News Online Science Editor Dr David Whitehouse
Scientists have discovered a new object orbiting the Sun after a
spaceprobe was mysteriously knocked off course.
Researchers have yet to identify the object, but they are
confident
it exists because of the way it appears to have deflected the
tiny
Pioneer 10 craft, which is hurtling out towards the stars.
If the observations are confirmed by other astronomers, it will
be
only the second time in history that a Solar System object has
been
discovered by its gravitational effect alone.
The first was the planet Neptune which was discovered in 1846.
Its
position was predicted because of its gravitational tug on the
planet
Uranus, which appeared to be behaving oddly following its
discovery
59 years earlier.
The new body, found by a team at Queen Mary and Westfield College
in
London, UK, and the Jet Propulsion Laboratory in California, is
probably a so-called Kuiper Belt object.
The astronomers looked at Pioneer 10's tracking data obtained
with
the Nasa Deep Space Network, an array of large radio telescopes
designed to communicate with far-off space probes.
Rocky swarm
On 8 December, 1992, when Pioneer was 8.4 billion km (5.2 billion
miles) away, they saw that it had been deflected from its course
for
about 25 days.
The scientists have been looking for such an effect for years and
are
currently analysing the data using several different methods to
confirm their findings.
In a few weeks time, they are expected to be able to place an
upper
limit on the mass of the object and make predictions about its
position. Early indications suggest it may be an object that is
being
ejected from our Solar System after encountering a major planet.
"We are quite excited that we have found one of these
events. It is a
very neat signal," Dr Giacomo Giampieri of Queen Mary and
Westfield
College told BBC News Online.
If confirmed, it would be one of over 100 known icy and rocky
objects
that circle the Sun at vast distances, mostly beyond the most
distant
planet Pluto.
They are small in planetary terms, just a few hundred kilometres
at
most, but astronomers believe there are millions of them swarming
around the Sun in a vast belt. The first one was detected in
1992.
Starbound probe
The Pioneer 10 spacecraft was launched in March 1972 and has
lived up
to its name.
It was the first spacecraft to travel through the asteroid belt,
the
ring of rocky debris that orbits the Sun between Mars and
Jupiter.
Before it successfully traversed this region of space, scientists
did
not know if a spacecraft could get through unharmed.
It was also the first craft to reach a gas-giant planet, Jupiter,
after which it left the solar system becoming the first craft to
effectively leave the Sun's planetary system, even though it has
not
yet passed into interstellar space.
It is currently 11 billion km (6.8 billion miles) away and still
transmitting even though Nasa ceased monitoring its signals in
1997
after it had spent 25 years in space.
Earlier this year, scientists were puzzled by what was described
as a
mysterious force acting on the probe. It led to speculation that
there was something wrong in our understanding of the force of
gravity.
Eventually the effect was tracked down to the probe itself, which
was
unexpectedly pushing itself in one particular direction. Pioneer
10
will reach the stars of the constellation of Taurus in about two
million years.
Copyright 1999, BBC
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