PLEASE NOTE:
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CCNet DIGEST, 27 April 1998
---------------------------
(1) OCEANIC IMPACT MIGHT HAVE INSPIRED ABORIGINAL LEGEND
Bob Kobres <bkobres@uga.edu>
(2) POPE ASSURES ITALIANS THE END IS NOT YET NIGH
THE TIMES, 24 April
(3) MODELLING CLOSE ENCOUNTERS WITH OPIK'S THEORY
G.B. Valsecchi et al., OBSERVATORY OF THE COTE
AZUR
(4) DYNAMICAL BEHAVIOUR OF EARTH ORBIT CROSSING ASTEROIDS
Y. Kozai, NATIONALL ASTRONOMICAL OBSERVATORY,
TOKYO
(5) SPACE GEOLOGY
Y.P. Dikov et al., MAX PLANCK INSTITUT FUR
CHEMIE
(6) HOW TO DESIGN A SOFT-LANDING LANDER
F. Doengi et al., DAIMLER BENZ AEROSPACE
(7) THE ESA COMET RENDEZVOUZ MISSION
P. Villefranche et al., MATRA MARCONI SPACE,
TOULOUSE
(8) HAS THE TAIL OF COMET HALE-BOPP A DUST-IMPACT ORIGIN?
W.H. Ip & L. Jorda, MAX PLANCK INSTITUT
FUR AERONAUTIC
(9) ROBOTIC MOBILITY ON ASTEROIDS AND COMETS
L. Richter, DLR, COLOGNE
(10) SPACE ROBOTICS IN EUROPE
P. Putz, EUROPEAN SPACE AGENCY
===============================
(1) OCEANIC IMPACT MIGHT HAVE INSPIRED ABORIGINAL LEGEND
From Bob Kobres <bkobres@uga.edu>
Sunday Herald Sun, July 6, 1997 <http://omzg.sscc.ru/tsulab/anew.html>
TSUNAMI LINK TO LEGEND by Graeme O'Neill
An Aboriginal legend long thought by historians to mark the
arrival of
white men in Australia may refer to a giant tidal wave. Geologist
Professor
Ted Bryant believes the legend of a "white wave"
that wiped
out Aboriginal culture more than 200 years ago tells of a natural
disaster that devastated the south coast of NSW after a comet
strike in
the Tasman Sea.
Most historians had assumed the legend referred to the coming of
white
men to Sydney Cove in January, 1788. Prof. Bryant told a major
international research conference in Melbourne this week that the
tidal
wave was one of two giant tsunamis that hit the NSW coast in the
past
1000 years.
The Wollongong University geologist estimates the tsunami was
moving at
about 350kmh when it hit the coast. He believes the earlier
tsunami,
which struck about 850 years ago, was probably even bigger.
Prof. Bryant linked the legend with a tsunami after he and a
colleague
found two telephone booth-sized boulders jammed one behind
another in a
crevice below a cliff face at Haycock Point near Merimbula. The
boulders were well above any normal storm surge.
"This legend talks about a white wave falling out of the sky
and
destroying their culture," he said.
"To an observer, a wave overtopping a headland and falling
into an
embayment would seem to come out of the sky."
"We know it happened at daytime, around midsummer, because
the legend
describes how the white wave came when it was very hot and
sultry, and
people were lying around resting."
"The legend describes how people went down to the coast the
next day
and found large new sea caves gouged out all along the
cliffs."
Prof. Bryant said the tsunami may be linked with a massive
underwater
mudslide on the continental shelf 50km off Wollongong, which left
a
debris fan 20km long and 10km wide on the sea floor -- its
collapse was
presumably triggered by a big earthquake.
"A slide of that volume would be big enough to give us our
tsunamis,"
he said.
But as Prof. Bryant and Dr. James Nott of James Cook University
searched the Australian coastline for more evidence of tsunamis,
another, almost incredible possibility emerged.
"You find the signs all around the coast, once you know what
you're
looking for, and we found tsunami debris on the south coast, in
Western
Australia and around Cairns, and all the radiocarbon dates were
similar," Prof. Bryant said.
"You can't have one big tsunami approaching different parts
of the
Australian coastline from opposite directions. Unless these
things are
much more frequent than we think, there must be another
explanation."
"We're toying with the idea that the tsunamis were created
by a comet
that broke into a couple of fragments that hit the oceans around
Australia."
Prof. Bryant said if giant tsunamis occur once every 600 years,
there
was a 15 per cent chance of one big tsunami in any century.
The frequency is consistent with recent evidence about the
frequency of
comet or asteroid-fragment impacts around the world.
Prof. Bryant told the 1997 Joint Assemblies of the International
Association of Meteorology and Atmospheric Sciences (IAMAS) and
the
International Association for Physical Sciences of the Oceans
(IAPSO)
that the impact of a tsunami on today's densely populated
coastline,
and coastal cities such as Sydney, Wollongong and Newcastle,
would be
enormous.
"Waves this big would ride right over Sydney Heads and get
into Sydney
Harbor, or could flood into Port Phillip Bay," he said.
"Once these things get into harbors, you can get four-metre
waves that
slosh back and forth for many hours, causing great damage,
especially
in low-lying areas."
===============================
(2) POPE ASSURES ITALIANS THE END IS NOT YET NIGH
From THE TIMES, 24 April
<http://www.sunday-times.co.uk:80/news/pages/Times/frontpage.html?1617548>
From Richard Owen in Rome
To the dismay of Seventh Day Adventists, Jehovah's Witnesses and
followers of Nostradamus, but to the relief of almost everyone
else,
the Pope has declared that the world is not about to end.
He said that it was doomed to end "at some point", but
there was no
fixed date, "nor can one be discerned from the Bible".
At his weekly
audience the Pope assured his listeners that the end of the world
was
not nigh, or anywhere near nigh, and said widespread fears that
the
new millennium would usher in the Last Judgment were unfounded.
Italy has been gripped by pre-millennial anxiety since the
earthquakes
in Umbria last September, which killed 11 people and damaged the
Basilica of St Francis at Assisi. There are frequent rumours that
Vesuvius, which destroyed Pompeii in AD79 and last erupted in
1944, is
about to erupt again. The Vatican has sought to reassure people
that
the mysterious Third Secret of Fatima - allegedly revealed by the
Virgin Mary to three Portuguese children in 1917 and kept secret
by the
Pope - does not predict Doomsday. But books on Fatima and
interpretations of the arcane predictions of Nostradamus, the
16th-century sage, remain sought-after in bookshops.
Speaking on "The Second Coming of Christ at the End of All
Things", the
Pope said that attempts to predict the end of the world were
"illusory
and misleading ... history is moving towards its conclusion, but
Christ
did not indicate any chronological deadline." Apocalyptic
visions were
to be taken "symbolically" as images of "the
precarious position of
humanity and the sovereign power of Christ".
Theological experts said biblical references to the Apocalypse
were at
best "open to interpretation", including the Revelation
of St John,
with its visions of plagues, earthquakes and "mountains of
fire"
ushering in "a new heaven and new earth".
(C) 1998, The Times Ltd.
==========================
(3) MODELLING CLOSE ENCOUNTERS WITH OPIK'S THEORY
G.B. Valsecchi*), C. Froeschle, R. Gonczi: Modelling close
encounters
with Opik's theory. PLANETARY AND SPACE SCIENCE, 1997, Vol.45,
No.12,
pp.1561-1574
*) OBSERVATORY OF THE COTE AZUR, BP 4229, F-06304 NICE, FRANCE
The results obtained by numerical integration of the equations of
motion of fictitious comets, in the restricted circular
three-dimensional three-body problem, are compared with those
obtained with Opik's theory of close encounters, for an
experimental
set-up similar to that used by Froeschle and Rickman (1980-1981)
to
model both the infeed of comets from the trans-jovian region into
the
Jupiter family and their subsequent orbital evolution within the
family. The distributions of perturbations in orbital energy E,
eccentricity e and inclination i are well reproduced by Opik's
theory,
as long as the comparison is made on the outcomes only up to a
certain
unperturbed distance b(max); several values of the latter are
experimented with and it is found that, surprisingly, Opik's
theory
seems to be still working reasonably well for the values of
b(max) in
excess of several times the Hill's radius of the planet. (C) 1998
Elsevier Science Ltd. All rights reserved.
===================
(4) DYNAMICAL BEHAVIOUR OF EARTH ORBIT CROSSING ASTEROIDS
Y. Kozai: Dynamical behaviour of Earth orbit crossing asteroids.
PLANETARY AND SPACE SCIENCE, 1997, Vol.45, No.12, pp.1557-1560
NATIONALL ASTRONOMICAL OBSERVATORY, MITAKA, TOKYO 181, JAPAN
Computing the maximum and minimum a values of the eccentricities
and
inclinations as functions of the arguments of perihelion for
about 7000
numbered asteroids by adopting a simple model it is found that 80
have
the minimum perihelion distances less than 1.04 AU. Still, it is
proved
that 20% of them have no chance of colliding with the Earth,
whereas 30
of them have relatively high collision probability as they have
orbits
similar to those of typical short-period comets. (C) 1998
Elsevier
Science Ltd. All rights reserved.
======================
(5) SPACE GEOLOGY
Y.P. Dikov, A.V. Ivanov, F. Wlotzka, E.M. Galimov, H. Wanke: High
enrichment of carbon and volatile elements in the surface layers
of
Luna 16 soil sample 1635: Result of comet or meteorite impact?
EARTH
AND PLANETARY SCIENCE LETTERS, 1998, Vol.155, No.3-4, pp.197-204
*) MAX PLANCK INSTITUT FUR CHEMIE, ABTEILUNG KOSMOCHEMIE,
D-55122
MAINZ, GERMANY
Surface analysis by X-ray photoelectron spectroscopy (XPS) in
combination with Ar etching was performed on a lunar regolith
sample
from the Luna 16 drill-core. The sample contains only similar to
10% of
glass spherules; these are of highly variable composition, which
distinguishes them from the pristine (volcanic) lunar glasses
with
their restricted compositional range. The XPS analyses revealed
that
practically all grains in this sample are coated by layers of
different
chemical composition. The outer 1200 Angstrom have a normal
Fe,Mg-
silicate composition. The middle zone between 1200 and 4400
Angstrom is
strongly enriched in carbon (up to 60 at%) and in Zn (4 at%).
From the
electron binding energy of the carbon atoms, it can be concluded
that
most of the carbon is present in the form of nanodiamonds and
graphite.
Other volatile elements (Cd, Pb, Ga, P, and Cl) were detected at
the
0.1-0.2 at% level in this zone. The inner zone below 4400
Angstrom has
again a silicate composition, but is more refractory than the
outer
zone, i.e. higher in Ca and Al. We propose that this layering was
formed by condensation from a carbon-rich cloud, originating from
the
impact of a comet or a carbonaceous chondrite-like body. XPS
analysis
of the surface layers showed variations in the chemical state of
the
main elements (Mg, Si, Al, Ca, Fe) in these layers, corresponding
to
different molecular structures. Similar variations were found in
condensate films produced in laser-pulse impact simulation
experiments.
(C) 1998 Elsevier Science B.V.
======================
(6) HOW TO DESIGN A SOFT-LANDING LANDER
F. Doengi, S.T. Burnage, H. Cottard, R. Roumeas: Lander
shock-alleviation techniques. ESA BULLETIN-EUROPEAN SPACE AGENCY,
1998,
No.93, pp.51-60
DAIMLER BENZ AEROSPACE, DORNIER SATELLITENSYSTEME GMBH,
FRIEDRICHSHAFEN, GERMANY
Future European space missions have been and are being discussed
which
involve the landing of scientific payloads on the surfaces of
planets
or comets in the Solar System, including Mars, Titan, the Moon
and
smaller remote comets. For all of these missions - Marsnet,
Intermarsnet, Ares, Rosetta, Euromoon, etc, - the landing
subsystem is
a critical element in that a single-point failure could
jeopardise the
success of the whole mission. Several studies have therefore been
performed to investigate potential landing devices and
strategies,
including the descent, impact, and post-impact stability and
operation
phases. They have shown that the acceleration peaks transferred
to the
lander structure during impact can be significantly higher than
expected, resulting in major risks to the integrity of the
scientific
payload, This article reviews work that has been performed
in this
domain as part of the Agency's Technology Research
Programme (TRP).
Copyright 1998, Institute for Scientific Information Inc.
====================
(7) THE ESA COMET RENDEZVOUZ MISSION
P. Villefranche, J. Evans & F. Faye: Rosetta: The ESA comet
rendezvous
mission. ACTA ASTRONAUTICA, 1997, Vol.40, No.12, pp.871-877
MATRA MARCONI SPACE, 31 RUE COSMONAUTES, F-31077 TOULOUSE, FRANCE
Rosetta was selected in November 1993 for the ESA Cornerstone 3
mission, to be launched in 2003, dedicated to the exploration of
the
small bodies of the solar system (asteroids and comets).
Following this
selection, the Rosetta mission and its spacecraft have been
completely
reviewed: this paper presents the studies performed the proposed
mission and the resulting spacecraft design. Three mission
opportunities have been identified in 2003-2004, allowing
rendezvous
with a comet. From a single Ariane 5 launch, the transfer to the
comet
orbit will be supported by planetary gravity assists (two from
Earth,
one from Venus or Mars); during the transfer sequence, two
asteroid
fly-bys will occur, allowing first mission science phases. The
comet
rendezvous will occur 8-9 years after launch; Rosetta will orbit
around
the comet and the main science mission phase will lake place up
to the
comet perihelion (1-2 years duration). The spacecraft design is
driven
(i) by the communication scenario with the Earth and its
equipment,
(ii) by the autonomy requirements for the long cruise phases
which are
not supported by the ground stations, (iii) by the solar cells
solar
array for the electrical power supply and (iv) by the navigation
scenario and sensors for cruise, target approach and rendezvous
phases.
These requirements will be developed and the satellite design
will be
presented. (C) 1998 Published by Elsevier Science Ltd. All rights
reserved.
============================
(8) HAS THE TAIL OF COMET HALE-BOPP A DUST-IMPACT ORIGIN?
W.H. Ip & L. Jorda: Can the sodium tail of comet Hale-Bopp
have a
dust-impact origin? ASTROPHYSICAL JOURNAL, 1998, Vol.496, No.1
Pt2,
p.L47
MAX PLANCK INSTITUT FUR AERONAUTIC, POSTFACH 20, D-37191
KATLENBURG
DUHM,GERMANY
Consideration is given to the possible mechanisms responsible for
the
production of the atomic sodium tail of comet Hale-Bopp. It is
shown
that both photosputtering and ion sputtering of nonvolatile dust
grains
might not be the main driving force. Instead, the generation of
impact
vapor by collisional interaction between the cometary dust coma
of
micron-sized particles and the very small grains (VSGs) of 10-100
Angstrom size could possibly account for the observations if a
large
amount of VSGs existed in the coma region. Copyright 1998,
Institute
for Scientific Information Inc.
==========================
(9) ROBOTIC MOBILITY ON ASTEROIDS AND COMETS
L. Richter: Principles for robotic mobility on minor solar system
bodies. ROBOTICS AND AUTONOMOUS SYSTEMS, 1998, Vol.23, No.1-2,
pp.117-
124
DLR, LINDER HOHE, D-51140 COLOGNE, GERMANY
For the coming years, a number of planetary missions to small
solar
system bodies such as asteroids and comets are being planned or
already
under development. Most of these projects aim at a fly-by or a
rendezvous with the target object. Inevitably, landing missions
to
small bodies will follow the first one being MUSES-C of ISAS
which is
to return a sample from the Near Earth Asteroid 4660 Nereus.
Within
Europe, ESA has selected the comet nucleus rendezvous mission
ROSETTA,
including a small lander, as Cornerstone 3 of its scientific
program
Horizon 2000. Eventually, missions will evolve which feature
mobile
robotic vehicles being able to traverse across the surface of an
asteroid or comet nucleus, enabling scientific and technological
investigations at a number of sites on the surface. This paper
outlines
the significant differences of mobility on small bodies as
compared to
larger planetary objects such as the Moon, Mars, or Mercury and
presents approaches for mobility on small bodies, based on the
principle of ballistic flight in the weak gravitational
field.
Finally, critical technology issues related to such free-flying
mobile
vehicles are discussed. (C) 1998 Elsevier Science B.V.
====================
(10) SPACE ROBOTICS IN EUROPE
P. Putz: Space robotics in Europe: A survey. ROBOTICS AND
AUTONOMOUS
SYSTEMS, 1998, Vol.23, No.1-2, pp.3-16
EUROPEAN SPACE AGENCY, ESTEC, POSTBOX 299, NL-2200 AG NOORDWIJK,
NETHERLANDS
Europe has been very active in developing space robotics systems
and
technology for close to 15 years. This survey paper serves as the
introduction to the Special Issue on Space Robotics in Europe. It
first
highlights the most significant differences between space and
terrestrial robots. Next, it structures the space applications
scenarios into internal and external robotics in Low Earth Orbit
(essentially the Space Stations), robotics for servicing of
geostationary satellites, for in-orbit assembly of large space
structures, and mobile robots (revers) and manipulator-type
robotics
for surface operations on the Moon, on Mars, on comets and on
asteroids. Finally, it gives an overview of the major European
space
robotic technology research and development programs. From this
context, it extensively refers to the individual papers of this
Special
Issue for more in-depth treatment. (C) 1998 Elsevier Science B.V.
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