PLEASE NOTE:
*
Date sent: Mon, 16
Feb 1998 09:59:26 -0500 (EST)
From:
Benny J Peiser B.J.PEISER@livjm.ac.uk
Subject: CC
DIGEST 16/02/98
To:
cambridge-conference@livjm.ac.uk
Priority: NORMAL
CAMBRIDGE-CONFERENCE DIGEST, 16 February 1998
---------------------------------------------
(1) SPACE BLAST IN BREACH OF MITCHEL PRINCIPLES: COSMIC
INTERVENTION IN
NORTHERN IRELAND PEACE PROCESS DEFUSED
New Scientist, 14 February 1998
(2) THE EUROPEAN FIREBALL NETWORK
J. Oberst et al., DLR, INSTITUTE OF PLANETARY
EXPLORATION, BERLIN
(3) DETERMINING THE PARAMETERS OF FRAGMENTING METEOROIDS
G.G. Novikov et al., ACADAMY OF SCIENCE OF THE
CZECH REPUBLIC,
(4) SPACE JUNK INCIDENT
Simon Mansfield simon@spacer.com "
(5) WHY FIXING IMPACT PROBABILITY IS REALLY DIFFICULT
Victor D. Noto vnn2@phoenixat.com
(6) MOON GETS OUT OF COMETS' WAY
SKY & TELESCOPE'S NEWS BULLETIN, FEBRUARY
13, 1998
(7) NASA RADAR REVEALS HIDDEN REMAINS OF ANCIENT CIVILISATION
IN
CAMBODIA
NASA News NASANews@hq.nasa.gov
=====================================
(1) SPACE BLAST IN BREACH OF MITCHEL PRINCIPLES: COSMIC
INTERVENTION IN
NORTHERN IRELAND PEACE PROCESS DEFUSED
From: NEW SCIENTIST, 14 February 1998, p. 5
An explosion in Northern Ireland that had been blamed on
terrorists was in
fact caused by a meteorite. A loud blast wakened the people of
Belleek at 5
am on 13 December 1997. On 6 January, a 1.2-metre-wide crater and
the
remains of an aluminium water trough and milk churn were
discovered. The
churn had a galssy rock fragment embedded in it. Tom Mason of the
Armagh
Planetarium believes a 20-centimetre fragment of the comet
Phaeton was
responsible.
=====================================
(2) THE EUROPEAN FIREBALL NETWORK
J. Oberst*), S. Molau, D. Heinlein, C. Gritzner, M. Schindler,
P. Spurny, Z. Ceplecha, J. Rendtel, and H. Betlem: The 'European
Fireball Network': Current status and future prospects.
METEORITICS &
PLANETARY SCIENCE, 1998, Vol.33, No.1, pp.49-56
*) DLR, INSTITUTE OF PLANETARY EXPLORATION, BERLIN, GERMANY
Among the three large camera networks carrying out fireball
observations through the seventies and eighties, the 'European
Fireball Network' is the last one still in operation. The network
today
consists of more than 34 all-sky and fish-eye cameras deployed
with similar
to 100 km spacing and covering an area of similar to 10(6) km(2),
in the
Czech and Slovak Republics, Germany, as well as parts of Belgium,
Switzerland, and Austria. Network operation results in similar to
10 000
image exposures per year, which represent on average 1200 h of
clear sky
observations-as imaging periods are restricted due to daylight,
moonlight,
and clouds. The cameras detect currently large meteors at a rate
of similar
to 50 per year; this is in good agreement with the encounter
rates
determined in previous fireball studies. From sightings of
'meteorite
candidates' (fireballs that may have deposited meteorites) and
meteorite
recoveries in the network area, we estimate that 15% of the
influx of
meteoritic matter is currently observed by the cameras, whereas
<1% is
recovered on the ground. Issues to be addressed by future
fireball
observations include the study of very large meteoroids (>1000
kg) for which
statistics are currently very poor and an examination of their
relationship
to NEOs (near-Earth objects) identified by current NEO search
programs.
Copyright 1998, Institute for Scientific Information Inc.
========================
(3) DETERMINING THE PARAMETERS OF FRAGMENTING METEOROIDS
G.G. Novikov*), P. Pecina, and N.A. Konovalova: The
determination of
the parameters of fragmenting meteoroids. ASTRONOMY AND
ASTROPHYSICS,
1998, Vol.329, No.2, pp.769-775
*) ACADAMY OF SCIENCE OF THE CZECH REPUBLIC, INSTITUE OF
ASTRONOMY,
CS-25165 ONDREJOV, CZECH REPUBLIC
Taking into account the quasi-continuous fragmentation of
meteor
particles, the formulae describing the variation of both light
and
ionization along the atmospheric trajectory of meteoroids, are
derived. Two methods of data processing are presented enabling
the
determination of the parameters of quasicontinuous fragmentation,
R-0, and R-1, characterizing the parent body and the
fragmentation
products, as well as the bulk density of the parent meteoroid
from
the light and/or ionization curve. The use of these methods is
shown
by means of two examples of processing of model curves. Copyright
1998, Institute for Scientific Information Inc.
===========================
(4) SPACE JUNK INCIDENT
From: Simon Mansfield simon@spacer.com "
http://www.aBCNEWS.com/sections/science/DailyNews/spacejunk0212.html
By James Oberg JamesOberg@aol.com
Special to ABCNEWS.com
Feb. 12 — A collision 240 miles above Earth last month
has U.S.
missile experts pondering the statistics of chance. The most
likely
explanation is "practically impossible," said one.
The third stage of a military missile launched from California
apparently collided with a piece of space debris and was
destroyed
within range of sensors on Kwajalein Island, a small atoll in the
western Pacific. A modified Minuteman-II Intercontinental
Ballistic
Missile (ICBM) was launched from Vandenberg Air Force Base at
7:25
p.m. PST on Jan. 15. It carried a collection of targets and dummy
warheads to test an anti-missile sensor on a missile to be
launched
from Kwajalein. That part of the exercise turned out
successfully.
But half an hour after launch, and about a minute before it
was to
hit the atmosphere, the discarded third stage of the missile
suddenly
disintegrated into a cloud of shrapnel, which burned up in the
atmosphere soon after. The fuel tank, about the size of a compact
car, was falling at about 5 miles per second. A grapefruit-sized
chunk of space debris was also zooming at about 5 mph on a
collision
course with the missile section.
"Apparently it did collide with some piece of space
junk,| said Lt.
Col. Rick Lehner, a spokesman for the Ballistic Missile Defense
Organization in Washington, D.C., the test’s sponsor.
Engineers reviewed data from radar screens and from telescopes on
the aircraft tracking the missile.
"The scope clearly showed a small object moving rapidly
from in-range
to out-range," said a witness who didn’t want his name
used. "When
its range coincided with the tank, it disappeared and the tank
slowly
changed from a single object to a cloud of targets."
Differing Data
The tracking data, however, is ambiguous, said Nicholas
Johnson,
NASA’s top expert on space debris. One radar using
frequencies better
suited to small objects saw both the tank and the
"intruder."
Although the visual records, which have not been released,
show a
streak approaching the tank horizontally, there’s no way to
determine
whether the streak was at the same altitude as the fuel tank.
The U.S. Space Command tracks about 7,000 objects in Earth
orbit
bigger than a few inches across, many of them fragments of rocket
explosions. But all attempts to correlate this object with any
catalogued space junk have been unsuccessful.
"They don’t know what it was," Lehner says.
Many thousands of
even-smaller pieces are known to be circling Earth, but they’re
too
small for accurate tracking or even detection. In recent decades,
concern has grown that space junk could pose a hazard to
satellites,
even manned space vehicles. Space experts believe that collisions
are
rare; most spacecraft failures—even those in which a
collision is
initially suspected—are caused from within.
Shuttles Steer Clear
On half a dozen occasions over the past decade, space shuttles
have
altered their flight paths to avoid predicted collisions. But
these
precautions were probably not really necessary. The Russian Mir
space
station, in orbit since 1986, has had a few tiny impacts and a
few
close calls, but has suffered no real damage from space junk.
Citing decades of flights, experts consider the odds of a missile
on
a half-hour flight actually hitting something in space to be
exceedingly remote, and they’re reluctant to believe it
could have
happened. The other explanation is even more worrisome—a
coincidental
explosion of a third stage might point to a defect that other
missiles may have.
Although the probability of a bizarre combination of other
circumstances—a self-induced explosion from leftover fuel
combined
with an unrelated space junk fly-by—may actually be much
less likely,
the Defense Department seems satisfied it was a freak accident
that
will probably never happen again.
==================
(5) WHY FIXING IMPACT PROBABILITY IS REALLY DIFFICULT
From: Victor D. Noto vnn2@phoenixat.com
Hi All:
What do you make of this post on the meteorobs list a few days
ago by
David McCarter?
I have it on my page http://www.phoenixat.com/~vnn2/mccarter.htm
-----------------------------------
From: David McCarter
At last summer's RASC General Meeting in Kingston Ont. Can.
the late
Eugene Shoemaker spoke about past earth cratering rates, and it
was
his thesis that there is a period of greater likelyhood of big
impacts every 33 million years, which roughly corresponds to the
rate
at which the solar system moves through the galactic plane.
His heart stopping conclusion was that we are actually overdue
by a
few years, give or take a million. After he left Kingston, I
understand he spoke on a similar topic to graduates at Acadia
University in Nova Scotia, and then left for Australia to
continue
his research.
At the RASC London centre 75th anniversary dinner last March
Dr. Paul
Chodas, JPL, showed his research using as an example comet
Hyautacki
to determine how difficult it really is to fix the probability of
a
direct hit upon earth. Had that comet been on a collision course,
the
numbers six weeks before impact (at discovery) would have
suggested a
near miss (as it did); three weeks before a very slim chance of a
hit, maybe 1%; a week before a 90% chance for a hit somewhere in
a
very big ellipse. Something like that anyway. In other words, the
observations are usually not nearly as accurate as required to be
definitive, and the further away the event, the more impossible
to
determine.
Of course, for all our military bravado, we are not able to
mount a
big Saturn/Energia mission in a few days or even weeks and in any
event the nudge we could currently give an approaching asteroid
would
have to be done years in advance.
He also concluded that the chaos of orbits in the inner solar
system
preclude accurate orbital determination over more than two to
five
years.
I hope I have not misrepresented either of these two
viewpoints to
you, but I think this subject needs far more attention than it is
getting. Eugene, Carolyn and Dave Levy were working from their
back
yards to further asteroid research. Hopefully the big military
project which is getting underway will be effective.
David McCarter
Professor Electronics General Servicing
Fanshawe College London, Ontario, Canada
R.A.S.C. London Centre VE3GS
=============================
(6) MOON GETS OUT OF COMETS' WAY
From: SKY & TELESCOPE'S NEWS BULLETIN, FEBRUARY 13, 1998
A waning Moon leaves the evening sky behind this week (and
heads
toward the total solar eclipse on the 26th) improving the odds of
seeing a pair of comets in the west after sunset. Comet
55P/Tempel-Tuttle, the parent of the Leonid meteor stream,
continues to move south through Pisces at 8th magnitude.
Observers
in mid-northern latitudes should look soon after sunset, as the
earlier you look in the west (to the upper right of Saturn) the
higher up in the sky the comet will be. More information about
the
comet can be found in the February issue of SKY &
TELESCOPE, page
91, and on SKY Online Comet Page
http://www.skypub.com/comets/comets.html.
Here are positions for
Tempel-Tuttle at 0 hours Universal Time in 2000.0 coordinates:
R.A. Dec.
February 15 01h 15m +15.4 deg.
17 01 15 +14.2
19 01 15 +13.2
Slightly higher above the horizon is Comet 103P/Hartley 2,
which is
about 9th magnitude. It is moving east through Aries. Its
positions
for the week are:
R.A. Dec.
February 15 03h 10m +02.0 deg.
17 03 19 +02.5
19 03 38 +02.9
Copyright 1998 Sky Publishing Corporation. S&T's Weekly
News Bulletin
and Sky at a Glance stargazing calendar are provided as a service
to
the astronomical community by the editors of SKY & TELESCOPE
magazine. Widespread electronic distribution is encouraged as
long as
these paragraphs are included. But the text of the bulletin and
calendar may not be published in any other form without
permission
from Sky Publishing (contact permissions@skypub.com or phone
617-864-7360). Illustrated versions, including active links to
related Internet resources, are available via SKY Online on the
World
Wide Web at http://www.skypub.com/.
=====================
(7) NASA RADAR REVEALS HIDDEN REMAINS OF ANCIENT CIVILISATION IN
CAMBODIA
From: NASANews@hq.nasa.gov
Douglas Isbell
Headquarters, Washington,
DC
February 12, 1998
(Phone: 202/358-1753)
Mary Hardin
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-0344)
RELEASE: 98-28
NASA RADAR REVEALS HIDDEN REMAINS AT ANCIENT ANGKOR
New evidence of a prehistoric civilization and remnants of
ancient
temples in Angkor, Cambodia, have been discovered by researchers
using
highly detailed maps produced with data from an airborne imaging
radar
instrument created by NASA.
Experts say the findings, made possible by the Airborne
Synthetic
Aperture Radar (AIRSAR) developed by NASA's Jet Propulsion
Laboratory
(JPL), Pasadena, CA, may revolutionize the way archaeologists
view the
ancient city's development.
Angkor is a vast complex of some 1,000 temples covering about
100
square miles of northern Cambodia. Little is known of the
prehistoric
occupation of this fertile flood plain, but at its height the
city housed an
estimated population of one million people. The famous temples
were built
from the eighth to thirteenth century AD and were accompanied by
a massive
hydrological system of reservoirs and canals. Today, much
of the
civilization of Angkor is hidden beneath a dense forest canopy
and is
inaccessible due to poor roads, land mines and political
instability.
"The radar data have enabled us to detect a distribution
of circular
'prehistoric' mounds and undocumented temples far to the
northwest of
Angkor," said Dr. Elizabeth Moore, Head of the Art and
Archaeology
Department at the School of Oriental and African Studies at the
University of London. "The site's topography is
highlighted by the
radar, focusing our attention on previously neglected features,
some at the
very heart of the city.
"The radar maps not only bring into question traditional
concepts of
the urban evolution of Angkor, but reveal evidence of temples and
earlier civilization either absent or incorrect on modern
topographic
maps and in early twentieth century archaeological reports,"
she said.
"The radar images make apparent many features that are
not readily
identifiable on the ground," said Dr. Anthony Freeman, a
radar
scientist at JPL who has collaborated with Moore for the past
three
years studying the use of radar on the Angkor site. "We can
see
differences in vegetation structure and some features that are
obscured by
vegetation cover."
In December 1997, Moore surveyed a small mound on the
perimeter of the
famous 12th century AD temple, Angkor Wat, that Freeman had first
noticed in
the radar image. "Previous archaeological accounts from 1904
and 1911 note
only two temples and make no mention of the distinct circular
form of the
mound. We found four to six temple remains, including
pre-Angkorean
structures," Moore said. "This suggests occupation of
the 12th century site
some 300 years earlier, radically changing accepted chronologies
of Angkor."
Angkor's beauty is seen in its temples, but the greatness of
the Khmer city
lies in the multitude of water-related constructions, according
to Moore.
The Khmer kings nominally dedicated temples to Hindu and Buddhist
deities,
but the underlying significance was veneration of ancestral
spirits,
ensuring fertility of the land. Management of water was
essential, both for
control during the monsoon rains and conservation during the dry
season and
involved the construction of moats, dikes, canals, tanks, and
reservoirs.
The largest of these reservoirs, dated to the 12th century AD, is
five miles
long and its function remains a matter of archaeological debate.
"These new detailed topographic maps have shown us many
more
hydrological features and highlighted how they function in the
rituals and daily life of the Khmer people," Moore
explained.
"Using a technique known as radar interferometry, which
combines two
images to create a three-dimensional topographic map, we can
construct a map
of the area surrounding Angkor that is more accurate than most
maps we have
of the United States," said Dr. Scott Hensley, a radar
engineer at JPL.
"This map lets us see both natural and human-made water
management features
at the site with great clarity."
"Angkor is situated on the edge of the Tonle Sap lake, a
unique body of
water that doubles in size during the rainy season. These maps
give us new
insights into the human impact on this ecosystem, from the
ancient Khmer to
the present day, and are of importance in the study of our
changing Earth,"
Freeman continued.
The Angkor radar images were taken in late 1996 as part of the
AIRSAR
Pacific Rim Deployment and were a follow-up to the 1994 study of
Angkor with
data collected by the Spaceborne Imaging Radar-C/X-band Synthetic
Aperture
Radar (SIR-C/X-SAR) that flew on NASA's Space Shuttle Endeavour.
Like SIR-C/X-SAR, AIRSAR transmits and receives three radar
frequencies in
both horizontal and vertical polarizations. While both systems
use C-band
and L-band wavelengths, AIRSAR has the added benefit of P-band, a
longer
wavelength that can penetrate below the forest canopy. In
addition, AIRSAR
can be flown in a mode called TOPSAR that allows it to measure
topography
and create three-dimensional images of the surface.
AIRSAR images of the Angkor region will be posted to the
Internet at
this address:
AIRSAR flies on a NASA DC-8 aircraft that is managed at NASA's
Dryden
Flight Research Center, Edwards, CA. The AIRSAR instrument
is managed by
JPL, a division of the California Institute of Technology, for
NASA's Office
of Earth Science, Washington, DC. This office manages NASA's
Earth Science
enterprise, an internationally coordinated effort to study
natural and
human-induced changes in the Earth's land, oceans, atmosphere,
ice and life.
The AIRSAR flight over Cambodia was funded by the Government
of
Thailand. Ground verification has been made possible by
Vann Molyvann,
Minister of State for Culture and Fine Arts, Territorial
Management, Urban
Planning and Construction; and Dr. Ang Choulan of the Cambodian
Authority
for the Protection and Management of Angkor and the Region of
Siem Reap.
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