PLEASE NOTE:
*
CCNet 119/2000 - 16 November 2000
---------------------------------
"The public should never again be shielded from uncertainty
-
however painful." -- Editorial, New Scientist, 4 November
2000.
Battlefield Earth
In war it's said that fifty thousand rounds are fired
for every casualty, so any veteran of battle
has been missed a thousand times at least.
The ones who don't return need only one to hit
to make them history.
Near Earth, our comfortable home, missiles abound.
Each century many hundreds pass nearby,
but Earth's a tiny target in a boundless space.
Until we recently began to look with dedicated tools
we rarely saw them.
The solar system has uncalculable millions
of orbiting fragments, some in the far Oort Cloud,
others that nearly cross our track from time to time.
We've found the places where the big ones struck
and left enormous scars.
Out there is something that can kill us all,
Something we might not see until too late.
But if we are prepared to look and learn
we still may have the time to find some way
to stop a fatal impact.
Alternatively, we could argue endlessly
That it's all a nonsense, and will never happen -
"those scars are ancient history; who cares what happened
to the dinosaurs? A warning? We know it's just a joke;
those things won't hit us - they never have!"
Malcolm Miller
stellar2@cyberone.com.au
16 November 2000
(1) THE DAY THE SOLAR WIND DISAPPEARED
Harvey Leifert <HLeifert@agu.org>
(2) LEONID METEOR SHOWER: SOWING THE SEEDS OF LIFE?
Space.com, 15 November 2000
(3) LEONIDS 2000: NICE METEOR SHOWER POSSIBLE, ANOTHER STORM
UNLIKELY
Cosmic Mirror, #209, 13 November 2000
(4) WANTED: LEONID METEOR SPOTTERS
Space Weather News
(5) ON THE SMALL ASTEROID 1994 GV
G. Sitarski
(6) CHAOTIC EVOLUTION OF (719) ALBERT, THE RECENTLY RECOVERED
MINOR PLANET
K. Tsiganis & H. Varvoglis
(7) DIFFUSION IN A SYMPLECTIC MAP WITH APPLICATION TO ASTEROID
MOTION
L.Y. Zhou et al.
(8) A CATALOG OF OBSERVED NUCLEAR MAGNITUDES OF JUPITER FAMILY
COMETS
G. Tancredi et al.
(9) TECHNOLOGY AND FIELD DEMONSTRATION OF ROBOTIC SEARCH FOR
ANTARCTIC
METEORITES
D.S. Apostolopoulos et al.
(10) PYRAMIDS LINED UP WITH THE STARS
BBC News Online, 15 November 2000
(11) ASTEROID TSUNAMI: SUB KM IMPACTORS UNLIKELY TO BE MAJOR
THREAT
Michael Paine <mpaine@tpgi.com.au>
(12) A CHAT ABOUT THE UK TASK FORCE REPORT
E.P. Grondine <epgrondine@hotmail.com>
(13) AND FINALLY: RUSSIA CANNOT PREDICT SAFE END TO MIR AS
REALITY OF
DE-ORBITING LOOMS
SpaceDaily, 16 November 2000
=================
(1) THE DAY THE SOLAR WIND DISAPPEARED
From Harvey Leifert <HLeifert@agu.org>
American Geophysical Union
Geophysical Research Letters
December 1, 2000
For more than a day, centered around midday (Universal Time) on
11 May 1999,
an unusually extended depression in the plasma density of the
solar wind
occurred in the vicinity of Earth. The density fell to 0.1-0.2
protons cm-3
compared with average solar wind densities of around 5 particles
cm-3. The
papers in this special section describe several aspects of this
unusual
event.
1. One consequence of the extremely tenuous solar wind was a
spectacular
expansion of the Earth's bow shock, captured as it passed by
several
spacecraft. See for example plots of the solar wind parameters in
Richardson
et al. ["Solar-cycle variation of low density solar wind
during more than
three solar cycles"] and
2. Terasawa et al. ["Geotail observation of anomalously low
density solar
wind in the magnetosheath"].
3. The shock reached record upstream distances, extending out to
at least
Lunar orbit (around 60 RE) [Earth radii = 60 times 6,371
kilometers or 3,950
miles]. While the solar source of this temporary decrease in the
number of
particles escaping the Sun remains elusive, Usmanov et al.
["A view of the
inner heliosphere during the May 10-11, 1999 low density
anomaly"] discuss a
possible association with an interval of strong rearrangement of
the global
magnetic field inferred from photospheric observations.
4. Another possible clue to the origin is the 11-year cycle in
the
occurrence rate of similar intervals of low-density solar wind
noted by
Crooker et al. ["Density extremes in the solar wind"]
and Richardson et al.
[See no. 1 above], from reviewing extended solar wind
observations. Such
intervals are rare during solar minimum, but become more frequent
near and
during the approach to solar maximum. Richardson et al. further
suggest that
low-density regions may be more prominent during weaker solar
cycles (e.g.,
cycle 20 and the current cycle).
5. Consequences of this unusual, extremely tenuous solar wind are
a steady
intense polar rain on the northern cusp region and a
dipolarization of the
geomagnetic field, extending as far as six Earth radii (Farrugia
et al.
["Response of the equatorial and polar magnetosphere to the
very tenuous
solar wind on May 11, 1999"]).
6. There are also subtle but global rearrangements of
magnetospheric
currents, with observable manifestation at very high magnetic
latitude
(Rostoker ["Ground magnetic signatures of ULF and substorm
activity during
an interval of abnormally weak solar wind on May 11, 1999"],
7. Ohtani et al. ["Dawn-dusk profile of field-aligned
currents on May 11,
1999: A familiar pattern driven by an unusual cause"], and
8. Papitashvili et al. ["Geomagnetic disturbances at high
latitudes during
very low solar wind density event"]).
**********
II. Authors referenced in the Highlights (in order of
appearance):
Special section
1. Ian G. Richardson, Daniel Berdichevsky, Michael D. Desch,
NASA/GSFC,
Greenbelt, Maryland; Charles J. Farrugia, Space Science Ctr., U.
New
Hampshire, Durham, New Hampshire.
2. Toshio Terasawa, Masahiro Hoshino, Dept. of Earth &
Planetary Scs., U.
Tokyo, Tokyo, Japan; Yasumasa Kasaba, Ken Tsubouchi, Toshifumi
Mukai,
Yoshifumi Saito, A. Nishida, Inst. of Space & Astronautical
Sc., Sagamihara,
Kanagawa, Japan; Louis A. Frank, William R. Paterson, Kent
Ackerson, Dept.
of Physics & Astronomy, U. Iowa, Iowa City, Iowa; Hiroshi
Matsumoto,
Hirotsugu Kojima, Radio Atmos. Sc. Ctr. Kyoto U., Gokasho, Japan;
Hiroshi
Matsui, Masaki Fujimoto, Tokyo Inst. of Tech., Ookayama, Meguro,
Japan;
David Larson, Robert Lin, T. Phan, Space Sc. Lab., U. California,
Berkeley,
California; John Steinberg, David McComas, Ruth Skoug, Los Alamos
National
Lab., Los Alamos, New Mexico.
3. Arcadi V. Usmanov, Inst. of Physics, U. St.-Petersburg,
St.-Petersburg,
Russia; Melvyn L. Goldstein, William M. Farrell, NASA/GSFC,
Greenbelt,
Maryland.
4. Nancy U. Crooker, Sheela Shodhan, J. Simmerer, Ctr. for Space
Physics,
Boston U., Boston, Massachusetts; John T. Gosling, John T.
Steinberg, Los
Alamos National Lab., Los Alamos, New Mexico; Ronald P. Lepping,
Lab. for
Extraterrestrial Physics, NASA/GSFC, Greenbelt, Maryland; Stephen
W. Kahler,
Air Force Res. Lab., Space Vehicles Directorate, Hanscom Air
Force Base,
Massachusetts.
5. Charles J. Farrugia, Space Sc. Ctr, U. New Hampshire, Durham,
New
Hampshire; Howard J. Singer, Daniel Evans, NOAA Space
Environmental Ctr.,
Boulder, Colorado; Daniel Berdichevsky, Keith W. Ogilvie, Richard
J.
Fitzenreiter, NASA/GSFC, Greenbelt, Maryland; Jack D. Scudder,
Dept. of
Physics & Astronomy, U. Iowa, Iowa City, Iowa; Christopher T.
Russell, Inst.
of Geophysics & Planetary Physics, UCLA, Los Angeles,
California.
6. Gordon Rostoker, Solar-Terrestrial Environmental Lab., Nagoya
U.,
Toyokawa, Japan.
7. Shin-Ichi Ohtani, Patrick T. Newell, Kazue Takahashi, The
Johns Hopkins
U. Applied Physics Lab., Baltimore, Maryland.
8. Vladimir O. Papitashvili, C. Robert Clauer, V. P. Suchdeo,
Space Physics
Research Lab., U. Michigan, Ann Arbor, Michigan; F. Christiansen,
V. A.
Pilipenko, Ole Rasmussen, J. F. Watermann, Solar-Terrestrial
Division,
Danish Meteorological Inst., Copenhagen, Denmark; V. Alexei
Popov, Inst. of
Terrestrial Magnetism, Ionosphere & Radio Wave Propagation,
Moscow, Russia.
**********
III. Notes, including ordering information
Authors are listed above, with institutional affiliations, in the
order in
which their papers appear in these Highlights. This information
is not
repeated in this form in GRL itself.
The Highlights and the papers to which they refer are not under
AGU embargo.
Journalists and public information officers of educational and
scientific
institutions (only) may receive one or more of the papers cited
in the
Highlights; send a message to Dawn McGee at
<dtate@agu.org>
(correct!), indicating which one(s). Include your name, the
name of your publication, and your fax number. If you did not
receive this
message directly from AGU, i.e., if you are not on the AGU
distribution
list, please provide your title, physical address, and phone
number as well.
Harvey Leifert
Public Information Manager
American Geophysical Union
2000 Florida Avenue, N.W.
Washington, DC 20009
U.S.A.
Phone (direct): +1 (202) 777-7507
Phone (toll-free in North America): (800) 966-2481 x507
Fax: +1 (202) 328-0566
Email: hleifert@agu.org
=============
(2) LEONID METEOR SHOWER: SOWING THE SEEDS OF LIFE?
From Space.com, 15 November 2000
http://www.space.com/cgi-bin/email/gate.cgi?lk=T3&date=001115&go=/searchforlife/leonids_biology_001115.html
By Robert Roy Britt
Data from instruments flown on airplanes during last year's
Leonid meteor
shower show that the seeds of life, long suspected to exist in
comet dust,
could have survived a fiery passage from space to Earth's ancient
atmosphere.
A range of findings, reported by an international team of
NASA-led
scientists, provide support for panspermia, which holds that life
on Earth
did not spring up spontaneously out of some primordial soup, but
was instead
seeded from space.
"Findings to date indicate that the chemical precursors to
life -- found in
comet dust -- may well have survived a plunge into early Earth's
atmosphere," said astronomer Peter Jenniskens of the Ames
Research Center
and the SETI Institute.
The studies were published in a November 14 special edition of
the
Netherlands journal Earth, Moon and Planets.
Sowing the seeds
The idea that the seeds of life, or life itself, constantly fall
from space
is the central idea of panspermia. Not only did life on Earth
begin this
way, the concept holds, but the genetic pool is constantly
modified, even
today.
Many mainstream scientists have long derided panspermia. But the
view has
shifted noticeably in recent months.
Other researchers have shown that meteors both small and large do
not heat
up as much as previously thought, allowing the possibility that
dormant life
could arrive on an incoming space rock or, just possibly,
embedded in the
dust grain of a comet.
Jenniskens and others said all this work at least supports the
notion that
life's recipe -- in the form of organic molecules -- can survive
the trip
into the atmosphere.
Chandra Wickramasinghe, a leading proponent of panspermia,
cheered the
newest work.
"I think the results reported by NASA are clear proof that
bacterial
particles could survive, hence vindicating panspermia,"
Wickramasinghe said.
He and astronomer Sir Fred Hoyle have, since the 1970s, argued
that organic
particles of bacterial sizes survive entry through the
atmosphere.
"However, there is still a tendency to interpret results
like this as merely
showing that organics, rather than life, are being added to the
Earth, but
the trend is surely moving towards panspermia,"
Wickramasinghe told
SPACE.com.
FULL STORY at
http://www.space.com/cgi-bin/email/gate.cgi?lk=T3&date=001115&go=/searchforlife/leonids_biology_001115.html
=================
(3) LEONIDS 2000: NICE METEOR SHOWER POSSIBLE, ANOTHER STORM
UNLIKELY
From Cosmic Mirror, #209, 13 November 2000
http://www.geocities.com/skyweek/mirror/209.html
Contrary to some sensationalist predictions already making the
rounds
another Leonid meteor storm, i.e. thousands of meteors per hour,
is highly
unlikely this year - a repeat of last years sky show (see Updates
# 158 and
186 story 2 plus eyewitness reports from Jordan and France)
remains likely
for next year, however (see the links in this announcement). In
2000, the
Earth will not come close to any of the dust trails which comet
Tempel-Tuttle has left behind, and thus most experts are not
expecting more
than a few hundred meteors per hour - and because of the
last-quarter Moon
in the sky, you won't even see that number, as the sky brightness
will
render fainter meteors invisible.
Still it is worth to go out and watch on the morning of November
18th. A
first peak, visible from western Europe and Africa (including
central
Europe) and NE South America, is expected around 3:44 UTC, which
is 4:44
a.m. local time for most of the favored continental European and
African
locations, 3:44 a.m. for the British Isles, mainland Portugal,
and the
Canary Islands, and 1.44 a.m. for eastern Brazil. A second peak,
visible
from large parts of North America, Central America, and NW South
America, is
expected around 7:51 UTC, which is 3:51 a.m. Atlantic Standard
Time, 2:51
a.m. Eastern Standard time, 1:51 Central Standard Time, and 0:51
a.m.
Mountain Standard Time. There is also a very vague chance that
enhanced
rates could be seen around 7:53 UTC on November 17th, also
favoring North
America.
"At the times mentioned above," the International
Meteor Organization
predicts, "an observer at the indicated locations may expect
to see 50 to
100 meteors per hour. A veritable meteor storm with several tens
of meteors
per minute as last year is much less likely this year, but not
ruled out.
Therefore, vigilance is called for! [...] In order to see
meteors, the sky
must be clear and the selected observing site should
preferentially be free
of light pollution; the less light, the more meteors will be
seen! Notice
that Leonid meteors cannot be seen before around midnight. Hence,
there is
no point in starting an observation earlier. Die-hards who do not
want to
miss anything of the show should then continue to watch until
dawn. People
who cannot afford to stay up that long should focus on a period
of 1 to 2
hours centered around the predicted peak time for their
region."
===============
(4) WANTED: LEONID METEOR SPOTTERS
From Space Weather News for Nov. 15, 2000
http://www.spaceweather.com
The 2000 Leonid meteor shower is just around the corner.
Forecasters expect
at least two outbursts of shooting stars as Earth passes through
debris from
comet Tempel-Tuttle this Friday and Saturday. Spaceweather.com
will post
current meteor counts and reports from around the world
beginning Thursday and continuing through the end of the shower.
We invite
all our readers to participate and report what they see.
All you need are
clear skies! Visit http://www.spaceweather.com
for more information and
observing tips.
And don't forget NASA's live webcast of the Leonids from the
stratosphere!
Visit http://www.leonidslive.com
for details.
===========
(5) ON THE SMALL ASTEROID 1994 GV
G. Sitarski: ACTA ASTRONOMICA 50: (3) 417-419 2000
Minor planet 1994 GV was observed during only three days but it
passed near
the Earth and ran over the 28-degree are on the sky. The orbit of
this minor
planet crosses the Earth orbit in the descending node. It
appeared that
according to this nominal orbit determined from the three-day
observation
are, a very close approach of the asteroid to the Earth to within
0.000114
a.u, could happen in April 2008. However, our investigations of
600 randomly
selected orbits as well as a search of the impact orbit excluded
a
possibility of a collision of 1994 GV with the Earth.
Copyright © 2000 Institute for Scientific Information
Addresses:
Sitarski G, Univ Bialystok, Inst Theoret Phys, Lipowa 41,
PL-15424
Bialystok, Poland.
Univ Bialystok, Inst Theoret Phys, PL-15424 Bialystok, Poland.
Polish Acad Sci, Space Res Ctr, PL-00716 Warsaw, Poland.
=============
(6) CHAOTIC EVOLUTION OF (719) ALBERT, THE RECENTLY RECOVERED
MINOR PLANET
K. Tsiganis & H. Varvoglis: ASTRONOMY AND ASTROPHYSICS 361:
(2) 766-769 SEP
2000
On May 9 the Mirror Planet Center announced the re-discovery of
the last
'lost' minor planet, (719) Albert. In this paper we study its
orbital
evolution. We show that Albert follows an extremely chaotic
orbit. typical
of near-Earth asteroids (NEAs) that are extracted from main belt
resonances
through close planetary encounters. It will become an
Earth-crosser and,
eventually, it will either be ejected from the solar system on a
hyperbolic
orbit or will become a Sun-grazer, most probably within the next
5 Myrs.
Copyright © 2000 Institute for Scientific Information
Addresses:
Tsiganis K, Univ Thessaloniki, Dept Phys, Sect Astronphys Astron
& Mech,
GR-54006 Salonika, Greece.
Univ Thessaloniki, Dept Phys, Sect Astronphys Astron & Mech,
GR-54006
Salonika, Greece.
===============
(7) DIFFUSION IN A SYMPLECTIC MAP WITH APPLICATION TO ASTEROID
MOTION
L.Y. Zhou, Y.S. Sun, J.L. Zhou: CHINESE PHYSICS LETTERS 17: (10)
708-710
2000
In studying a 2-dimensional symplectic map, the exponential law
and
algebraic law are observed in the diffusion of orbits in the
phase space.
The diffusion time in the vicinity of an island is investigated
carefully
and a logarithm law is found for the first time. The distribution
of
asteroids in the main belt and the diffusion velocities in 3:2
and 4:3
resonances are discussed using this map. Copyright © 2000
Institute for
Scientific Information
Addresses:
Zhou LY, Nanjing Univ, Dept Astron, Nanjing 210093, Peoples R
China.
Nanjing Univ, Dept Astron, Nanjing 210093, Peoples R China.
==============
(8) A CATALOG OF OBSERVED NUCLEAR MAGNITUDES OF JUPITER FAMILY
COMETS
G. Tancredi, J.A. Fernandez, H. Rickman, J. Licandro: ASTRONOMY
&
ASTROPHYSICS SUPPLEMENT SERIES
146: (1) 73-90 OCT 2000
A catalog of a sample of 105 Jupiter family (JF) comets (defined
as those
with Tisserand constants T > 2 and orbital periods P < 20
yr) is presented
with our "best estimates" of their absolute nuclear
magnitudes H-N =
V(1,0,0). The catalog includes all the nuclear magnitudes
reported after
1950 until August 1998 that appear in the International Comet
Quarterly
Archive of Cometary Photometric Data, the Minor Planet Center
(MPC) data
base, IAU Circulars, International Comet Quarterly, and a few
papers devoted
to some particular comets, together with our own observations.
Photometric
data previous to 1990 have mainly been taken from the Comet Light
Curve
Catalogue (CLICC) compiled by Kamel (1991). We discuss the
reliability of
the reported nuclear magnitudes in relation to the inherent
sources of
errors and uncertainties, in particular the coma contamination
often present
even at large heliocentric distances. A large fraction of the JF
comets of
our sample indeed shows various degrees of activity at large
heliocentric
distances, which is correlated with recent downward jumps in
their
perihelion distances. The reliability of coma subtraction methods
to compute
the nuclear magnitude is also discussed. Most absolute nuclear
magnitudes
are found in the range 15 - 18, with no magnitudes fainter than
H-N <similar
to> 19.5. The catalog can be found at: http://www.fisica.edu.uy/gonzalo/catalog/
.
Copyright © 2000 Institute for Scientific Information
Tancredi G, Fac Ciencias, Dept Astron, Igua 4225, Montevideo
11400, Uruguay.
Fac Ciencias, Dept Astron, Montevideo 11400, Uruguay.
Astron Observ, S-75120 Uppsala, Sweden.
Inst Astrofis Canarias, E-38200 La Laguna, Tenerife, Spain.
==============
(9) TECHNOLOGY AND FIELD DEMONSTRATION OF ROBOTIC SEARCH FOR
ANTARCTIC
METEORITES
D.S. Apostolopoulos, M.D. Wagner, B.N. Shamah, L. Pedersen, K.
Shillcutt,
W.L. Whittaker:
INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH 19: (11) 1015-1032 NOV
2000
Meteorites are the only significant source of material from other
planets
and asteroids, and therefore are of immense scientific value.
Antarctica's
frozen and pristine environment has proven to be the best place
on earth to
harvest meteorite specimens. The lack of melting and surface
erosion keep
meteorite falls visible on the ice surface in pristine condition
for
thousands of years. In this article, we describe the robotic
technologies
and field demonstration that enabled the first discovery of
Antarctic
meteorites by a robot. Using a novel autonomous control
architecture,
specialized science sensing, combined manipulation and visual
servoing, and
Bayesian classification, the Nomad robot found and classified
five
indigenous meteorites during an expedition to the remote sire of
Elephant
Moraine in January 2000. This article first overviews Nomad's
mechatronic
systems and details the control architecture that governs the
robot's
autonomy and classifier that enables the autonomous
interpretation of
scientific data. It then focuses on the technical results
achieved during
field demonstrations at Elephant Moraine. Finally, the article
discusses the
benefits and limitations of robotic autonomy in science missions.
Science
autonomy is shown as a capable and expandable architecture for
exploration
and in situ classification. Inefficiencies in the existing
implementation
are explained with a focus on important lessons that outline
future work.
Copyright © 2000 Institute for Scientific Information
Addresses:
Apostolopoulos DS, Carnegie Mellon Univ, Inst Robot, Pittsburgh,
PA 15213
USA.
Carnegie Mellon Univ, Inst Robot, Pittsburgh, PA 15213 USA.
=============
(10) PYRAMIDS LINED UP WITH THE STARS
From the BBC News Online, 15 November 2000
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1024000/1024779.stm
By BBC News Online science editor Dr David Whitehouse
Ancient Egyptian astronomers aligned the pyramids due north by
using two
stars that circle the celestial polar point.
Nearly 4,500 years ago, each star was about 10 degrees from the
celestial
pole which lay directly between them. When one star was exactly
above the
other in the sky, astronomers could find a line that pointed due
north.
But the alignment was only true for a few years around 2,500 BC.
Before and
after that time, the stars deviated from the north-south line and
anyone
using the stars to plot a direction would have made errors.
And it is these mistakes that a British Egyptologist now believes
can be
used to estimate very accurately when the pyramids were built.
Her theory
suggests that the Great Pyramid at Giza was constructed within 10
years of
2,480 BC.
'Indestructible' stars
Kate Spence is from the University of Cambridge. She developed
her theory
while trying to explain the deviations in the alignment of the
bases of many
pyramids from true north.
She believes the ancients may have used a pair of fairly bright
stars, which
in 2,467 BC lay precisely along a straight line that included the
celestial
pole.
"We know that the ancient Egyptians were extremely
interested in the night
sky, particularly the circumpolar stars," she told the BBC.
"These circle around the North Pole, and as you can always
see them, the
Egyptians always referred to them as 'The Indestructibles'.
"As a result, they became closely associated with eternity
and the king's
afterlife. So that after death, the king would hope to join the
circumpolar
stars - and that's why the pyramids were laid out towards
them."
Ancient astronomy
The north-finding stars were Kochab, in the bowl of the Little
Dipper (Ursa
Minor), and Mizar, in the middle of the handle of The Plough or
Big Dipper
(Ursa Major).
An Egyptian astronomer would have held up a plumb line and waited
for the
night sky to slowly pivot around the unmarked pole as the Earth
rotated.
When the plumb line exactly intersected both stars, one about 10
degrees
above the invisible pole and the other 10 degrees below it, the
sight line
to the horizon would aim directly north.
However, the Earth's axis is unstable and wobbles like a
gyroscope over a
period of 26,000 years. Modern astronomers now know that the
celestial north
pole was exactly aligned between Kochab and Mizar only in the
year 2,467 BC.
Either side of this date, the ancient astronomers trying to find
true north
would lose some accuracy.
Writing in the journal Nature, Kate Spence shows that the
orientation errors
of earlier and later pyramids faithfully track the slow drift of
Kochab and
Mizar with respect to true north.
And because the error in the Kochab-Mizar alignment can be
readily
calculated for any date, the error in each pyramid's orientation
corresponds
to a period of several years.
Owen Gingerich, of the Harvard-Smithsonian Center for
Astrophysics,
Cambridge, Massachusetts, said: "Spence has come up with an
ingenious
solution to a long-standing mystery."
Copyright 2000, BBC News Online
-----------
Kate Spence: Ancient Egyptian chronology and the astronomical
orientation of
pyramids
Nature 408, 320 - 324 (2000), 16 Nov 2000
Abstract: The ancient Egyptian pyramids at Giza have never been
accurately
dated, although we know that they were built approximately around
the middle
of the third millennium BC. The chronologies of this period have
been
reconstructed from surviving lists of kings and the lengths of
their reigns,
but the lists are rare, seldom complete and contain known
inconsistencies
and errors. As a result, the existing chronologies for that
period (the Old
Kingdom) can be considered accurate only to about 100
years, a figure that
radiocarbon dating cannot at present improve. Here I use trends
in the
orientation of Old Kingdom pyramids to demonstrate that the
Egyptians
aligned them to north by using the simultaneous transit of two
circumpolar
stars. Modelling the precession of these stars yields a date for
the start
of construction of the Great Pyramid that is accurate to 5 yr,
thereby
providing an anchor for the Old Kingdom chronologies.
============================
* LETTERS TO THE MODERATOR *
============================
(11) ASTEROID TSUNAMI: SUB KM IMPACTORS UNLIKELY TO BE MAJOR
THREAT
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
Andy Smith (CCNet 15 Nov) writes "A third-of-a-kilometer
rock, in the
Atlantic, could destroy all of the coastal cities". I should
point out that
several tsunami experts now consider that it would take an
impactor at least
one kilometre in diameter to cause an appreciable tsunami
around the perimeter of an ocean. I have covered the issue of
differences
between tsunami predictions on the webpage
http://www1.tpgi.com.au/users/tps-seti/spacegd7.html
and in more detail in
my paper 'Asteroid Impacts: the Extra Hazard due to Tsunami',
Science of
Tsunami Hazards, Vol 17, N0.3 (1999). A 9.8Mb PDF download of the
entire
'Mega-tsunami' volume is available at http://epubs.lanl.gov/tsunami/
and
abstracts are at
http://www.ccalmr.ogi.edu/STH/abstracts.html
regards
Michael Paine
=========
(12) A CHAT ABOUT THE UK TASK FORCE REPORT
From E.P. Grondine <epgrondine@hotmail.com>
Hello Benny -
I had a chance to speak about the prospects for the UK NEO
telescope with
Dr. Colin Hicks, Director General of the British National Space
Centre, at
the reception which Italian Embassy held for participants to the
International Space Symposium, which was held in Washington from
October
25-26.
In a word, the answer is NO, at least for the project as it is
now proposed.
Dr. Hicks was firm that the UK will not act alone in major space
science
efforts, but only as part of the ESA. He sees UK participation in
ESA's GAIA
as fulfilling the need for NEO detection resources, and if I
understood his comments correctly, NEO observers can expect his
support in
getting time on this telescope from the cosmologists. I'm not an
astronomer,
so I leave it to the astronomers here to analyze how effective
GAIA will be
in searching for NEOs.
My opinion is that there is still hope for a dedicated
"UK" NEO Telescope,
but only if the program is redesigned as an all-Europe project,
one with
perhaps housing buildings from Sweden or Norway, mounts from
Germany,
computers from France, software from Italy, and staff support
from
Spain, or some such division, with all European NEO observers
working
jointly at the facility. I have to say that upon reflection
I have to agree
with Dr. Hicks; I have often spoke about the need for others
besides the US
taxpayers to foot the bill for the NEO detection effort, and
there is no
reason why UK taxpayers should have to foot the bill for a
European NEO
effort.
Conference participants will be delighted to learn that Dr. Hicks
has a
pretty firm understanding of the impact hazard. He instantly
pointed out
that if you have 3 land impacts in the last 150 years, you're
going to have
7 impacts over water, and I confirmed his speculation, mentioning
that
information compiled from ships' logs, which I had misplaced. I
also briefly
disucssed with Dr. Hicks the Rio Cuarto event and other possible
large fatal
impact events.
The UK NEO Taskforce emphasized in the conclusions to their
report the need
to poll other European governments about their plans for dealing
with the
impact hazard. The Taskforce was working within within the
evolving
worldview of a UK as a member of the Commonwealth, the
Anglo-American
alliance, and Europe, and given the extremely short time
constraints imposed
upon them, they chose to survey the US first, where NEO detection
efforts
have been given the most money so far. I think that their
recommendation to
co-ordinate within Europe definitely needs to be acted upon, and
some
committee set in place. In the meantime it may be possible
for the
telescope makers there at Liverpool to prepare the way towards an
all-Europe
project through their own contacts with the scientists and
scientific
manufacturers in other European countries.
Best wishes -
EP
MODERATOR'S NOTE: I understand that the conversation reported by
Ed Grondine
was more a cocktail party chat and that reference to
international efforts
through ESA were clearly not confined to ESA. GAIA is an
important part of
the equation, but on current time scales more the long stop or
final mopping
up activity of future European initiatives as well as possibly
(with other
missions) demonstrating one way that the ongoing monitoring of
NEOs could be
done in a decade or two. The suggestion that ESA's GAIA space
telescope
could be used is for future NEO searches is, of course, only one
of the
recommendations by the UK Task Force. However, GAIA will not fly
for many
years (expected launch in or around 2009). More importantly,
however, GAIA
is not designed to detect those NEOs (i.e. >500m) which are
the *main*
concern of the UK Task Force. The position that the UK will not
fund a large
dedicated NEO search telescope on its own and is instead seeking
EU partners
for the recommended search instrument, is consistent with
previous
statements made by the Government and the Science Minister
himself.
Nevertheless, it is important to stress that this argument should
not be
used as a reason to put the recommended 3m class telescope and/or
other Task
Force recommendations on the long finger. Instead, the Science
Minister
needs to appreciate that the implementation of the Task Force
Report, rather
than a cherry-picked version, would put the Government in a
win-win
situation. The truth of the matter is that there is growing
political
support from an increasing number of MPs, MEPs and Peers for the
UK to take
the initiative now and to lobby our European partners for sharing
the
collective responsibility with regards to the impact hazard. The
public and
the media, both in the UK and internationally, have given the UK
Government
much credit for setting up the NEO Task Force and the
exceptionally
far-sighted Report it has produced. Accepting its recommendations
would not
only generate general praise and applause. It would certainly
help to
generate much needed public support for the Government,
particularly in
those regions of the UK (i.e. the North West and Northern
Ireland) where
local MPs are now expecting tangible results from the
implementation of the
recommendations. Rejecting them, however, would threaten to wipe
out the
respect and approbation the Government has gained as a result of
its
preparatory actions over the impact hazard. BJP
=============
(13) AND FINALLY: RUSSIA CANNOT PREDICT SAFE END TO MIR AS
REALITY OF
DE-ORBITING LOOMS
From SpaceDaily, 16 November 2000
http://www.spacedaily.com/news/mir-00zzj.html
Moscow (Interfax) Nov. 15, 2000
It is impossible to guarantee that the Russian space station Mir
will come
down in the safe area of the Pacific Ocean defined for it,
Anatoly Kiselyov,
director general of the state-run Khrunichev space research
center, told
Interfax on Wednesday. It would be unrealistic to try to build a
highly
accurate mathematical model of the braking, reentry of dense
layers of the
atmosphere, passing through the atmosphere and falling into the
ocean for a
130-ton complex consisting of numerous modules with a large
surface area,
Kiselyov said.
The situation in lower space and in the atmosphere changes daily,
he said.
"It depends on numerous factors such as solar flares, the
relative positions
of the planets and variations of atmospheric density," he
said.
Engineers know for sure that the very strong steel spherical
bottles, parts
of large frames in the main module and Kvant, Kristall, Spektr
and Priroda
modules, gyros and rocket engines will not burn up in the
atmosphere and
will fall to earth, Kiselyov continued.
Station elements will fall over a swath 8,000-10,000 kilometers
long and 200
kilometers wide, he said. There is some probability that they
will fall over
land, Kiselyov said.
"There are several ways of de-orbiting the Russian orbital
complex and
sinking it in the desired area of the Pacific Ocean. I favor the
de-
orbiting control from inside the station, with the crew
supervising the
descent and the initial phase of braking from inside the
station," Kiselyov
said.
The preparation for de-orbiting will take a lot of time because
all the
cables laid through the modules during the 14 years of the
station's life
have to be disconnected, the fixtures from inter-modular hatches
removed and
the accuracy of the initial braking thrusts the of rocket engines
supervised, he said.
Russian Aerospace Agency head Yuri Koptev has been reported as
saying that
the Russian Cabinet might pass an resolution concerning the final
stage of
operating Mir on Thursday.
The Russian government at its Thursday session is expected to
approve a
resolution on the final stage of use for the space station Mir,
director of
the Russian Aerospace Agency Yuri Koptyev told Interfax on
Wednesday.
He said that Mir has been operating in orbit for about 14 years.
The draft
resolution binds the ministries of foreign affairs, emergency
situations,
defense and others to compose a package of documents to guarantee
the safe
withdrawal of Mir from operation.
Koptev said that under international agreements, Russia is
responsible to
other countries for the safe removal of its spacecraft from
orbit.
"We must guarantee that Mir will not drop on someone, to put
it plainly," he
said. There was a case when a military satellite with a nuclear
reactor fell
on Canadian territory, he said.
News Flash
Fate Of Mir Postponed Until Safety Concerns Settled
Moscow (AFP) Nov. 16, 2000 - Russia has postponed a final
decision on
abandoning the ageing Mir space station amid safety concerns
about the
destruction of the Soviet-era orbiter, a space agency official
said
Wednesday. The government expected to announce the decision
"within the next
month," Sergei Gorbunov, chief spokesman for the agency told
AFP.
Copyright 2000 Interfax.
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