PLEASE NOTE:
*
CCNet 50/2002 - 18 April 2002
-----------------------------
"The stand-offish dance of two asteroids at the outer
reaches of the
Solar System is captivating astronomers. The two rocky objects,
discovered locked in mutual orbit, could tell us about the
properties
of the far-flung Kuiper belt.... The new discovery challenges
existing
theories of how two asteroid-like bodies can become bound
together by their
gravitational pull. Researchers are not yet clear why the two
rocks have not
been ripped apart by interactions with other bodies in the Kuiper
belt."
--Philip Ball, Nature, 17 April 2002
"With a Japanese space mission planned to bring asteroid
samples
back to Earth and drop them on Australia, the government down
under is
studying what's up in regards to possible contamination and
quarantine
procedures that might be needed. Biosecurity Australia, a group
within
that the country's Department of Agriculture, Fisheries and
Forestry, is
developing quarantine protocols for an exotic import from
space."
--Leonard David, SPACE.com, 17 April 2002
(1) OBSERVATORY JOINS ASTEROID WATCH
The Scotman, 18 April 2002
(2) DEAR, OH DEAR: "ASTEROID STRIKE MUSEUM OPENS" (Have
we got communication
problems, or what?)
Ananova, 18 April 2002
(3) HUBBLE HUNTS DOWN ODD COUPLE AT THE FRINGES OF OUR SOLAR
SYSTEM
Ron Baalke <baalke@jpl.nasa.gov>
(4) ROCKS TWIRL IN REMOTE TWO-STEP
Nature Science Update, 18 April 2002
(5) AUSTRALIA PREPARES FOR ASTEROID SCAVANGER'S OTHERWORLDLY
CARGO
Space.com, 17 April 2002
(6) WALKING WITH DINOSAURS?
BBC News Online, 17 April 2002
(7) AGE OF EMPEROR HAWAII CHAIN
Hermann Burchard <burchar@mail.math.okstate.edu>
(8) RIO CUARTO IMPACT DATE
Yvan Dutil <yvan.r.dutil@ca.abb.com>
(9) FUTURE MARTIANS WOULD RELISH IMPACTS
Oliver Morton <abq72@pop.dial.pipex.com>
(10) MARTIANS WILL ENJOY REPRESENTATION WITHOUT TAXATION
Jens Kieffer-Olsen <dstdba@post4.tele.dk>
(11) APPRECIATION FOR CCNet
Don Stockbauer <donstockbauer@hotmail.com>
(12) GREAT BALLS OF FIRE
Bob Kobres <bkobres@arches.uga.edu>
==================
(1) OBSERVATORY JOINS ASTEROID WATCH
>From The Scotman, 18 April 2002
http://news.scotsman.com/scitech.cfm?id=412502002
ALASTAIR DALTON SCIENCE CORRESPONDENT
FEARS of an asteroid hitting Earth have led to a network of
research centres
to provide information about the risk.
Scientists hope the centres, including one in Edinburgh, will
help to assess
future reports of new Earth-bound asteroids.
The development follows a series of recent alerts about asteroid
strikes,
including a half-mile wide object that has a one in 300 chance of
hitting
the Earth in 2880. The Near Earth Object Information Centre
(NEOIC) is being
established at the National Space Centre in Leicester. It will be
linked to
the Royal Observatory, on Blackford Hill in Edinburgh, and other
centres in
Belfast and London.
The Leicester centre opens on Saturday, the 126th anniversary of
the only
iron meteorite to hit Britain, an 8lb object that made an 18in
hole at
Rowton in Shropshire.
Dr John Davies, an astronomer at the Royal Observatory and a
member of the
NEOIC expert panel, said the centres would provide people with
information
while impact risks were assessed.
Dr Davies, who has studied asteroids for 15 years, said: "We
do not yet know
the probability of an object hitting the Earth [sic], so we
cannot yet
decide whether we should be concerned or not [sic].
"We need to make people understand there is a risk, but that
we do not fully
understand it. The centres should help people assess the
implications of new
reports as they appear by understanding the processes that
astronomers use
in finding, following and mapping objects.
"After such objects are first reported, several days of
observations of
their orbit are required, and there is always going to be some
uncertainty
about the threat they pose," he added.
Dr Davies said he would be opposed to withholding information
about
potential new threats from space objects until the risk was fully
assessed.
He said astronomers could be accused of a cover up, and such
information was
likely to leak out from the scientific community anyway.
Astronomers have calculated that the solar system contains about
700,000
asteroids which are large enough to destroy human life.
However, Dr Davies said the risk will not be fully assessed for
ten years,
and smaller objects, less than 300ft across, may not be spotted
until they
became bright enough, when they are close to the Earth.
The European Space Agency will use its Gaia telescope mission in
2010 to
search an asteroid "blind spot" between the Earth and
the sun.
Dr Davies said there were 100,000 such objects that could hit
Earth, which
would have an impact 3,000 times more powerful than the atomic
bomb dropped
on Hiroshima.
In the last major incident, in 1908, an object more than 150ft
long
devastated several square miles of forest in Siberia after it
exploded in
the Earth's atmosphere.
Asteroids are concentrated in a belt between Mars and Jupiter but
can be
thrown into different orbits. They are termed meteorites after
they have hit
the Earth.
Meanwhile, the Royal Observatory yesterday exhibited technology
originally
developed for space research that has been adapted for commercial
use. The
display included imaging equipment used for dental checks and
breast
screening.
The Medipix detectors, developed by Glasgow University, use
30-times less
power than traditional X-rays for teeth examinations, reducing
the risk of
radiation exposure.
Copyright 2002, The Scotsman
===========
(2) DEAR, OH DEAR: "ASTEROID STRIKE MUSEUM OPENS" (Have
we got communication
problems, or what?)
>From Ananova, 18 April 2002
http://www.ananova.com/news/story/sm_569483.html?menu=news.scienceanddiscovery
A new space centre is opening to study the likelihood of earth
being hit by
an asteroid or comet.
The National Space Centre is to play a vital role in warning of
the risks of
earth being hit by asteroids.
The Leicester-based centre will become home to the UK's first
[sic]
Information Centre on Near Earth Objects.
It will be backed by £300,000 of government funds over the next
three years
and experts based there will analyse [sic] the threat of a direct
hit by any
of the hundreds of potentially hazardous objects in space so far
identified.
The centre will work with the Natural History Museum in London
and a
consortium involving the University of Leicester, Queen's
University,
Belfast, Queen Mary College, London and the Royal Observatory in
Edinburgh.
Lord Sainsbury, who made the announcement on the new centre,
explained: "The
potential threat from NEO's to our planet has been an issue of
increased
national interest and concern over recent years."
He added: "By setting up an information centre we are
helping the UK play a
full and prominent role in an area that requires international
rescue."
Copyright 2002, Ananova
=============
(3) HUBBLE HUNTS DOWN ODD COUPLE AT THE FRINGES OF OUR SOLAR
SYSTEM
>From Ron Baalke <baalke@jpl.nasa.gov>
Donald Savage
Headquarters,Washington
April 17, 2002
(Phone: 202/358-1727)
Ray Villard
Space Telescope Science Institute, Baltimore
(Phone: 410/338-4514)
Nancy Neal
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-0039)
Christian Veillet
Canada-France-Hawaii Telescope Corporation, Kamuela, Hawaii
(Phone: 808/885-3161)
RELEASE: 02-70
HUBBLE HUNTS DOWN ODD COUPLES AT THE FRINGES OF OUR SOLAR
SYSTEM
NASA's Hubble Space Telescope is hot on the trail of an
intriguing new class
of solar system object that might be called a Pluto
"mini-me" -- dim and
fleeting objects that travel in pairs in the frigid, mysterious
outer realm
of the solar system called the Kuiper Belt.
In results published today in the journal Nature, a team of
astronomers led
by Christian Veillet of the Canada-France-Hawaii Telescope
Corporation
(CFHT) in Kamuela, Hawaii, is reporting the most detailed
observations yet
of the Kuiper Belt object (KBO) 1998 WW31, which was discovered
four years
ago and found to be a binary last year by the CFHT.
Pluto and its moon Charon and countless icy bodies known as KBOs
inhabit a
vast region of space called the Kuiper Belt. This
"junkyard" of material
left over from the solar system's formation extends from the
orbit of
Neptune out to 100 times as far as the Earth is from the Sun
(which is about
93 million miles) and is the source of at least half the
short-period comets
that whiz through our solar system. Only recently have
astronomers found
that a small percentage of KBOs are actually two objects orbiting
around
each other, called binaries.
"More than one percent of the approximately 500 known KBOs
are indeed
binary: a puzzling fact for which many explanations will be
proposed in what
is going to be a very exciting and rapidly evolving field of
research in the
coming years," says Veillet.
Hubble was able to measure the total mass of the pair based on
their mutual
570-day orbit (a technique Isaac Newton used 400 years ago to
estimate the
mass of our Moon). Together,
the "odd-couple" 1998 WW31 is about 5,000 times less
massive than Pluto and
Charon.
Like a pair of waltzing skaters, the binary KBOs pivot around a
common
center of gravity. The orbit of 1998 WW31 is the most eccentric
ever
measured for any binary solar-system object or planetary
satellite. Its
orbital distance varies by a factor of ten, from 2,500 to 25,000
miles
(4,000 to 40,000 kilometers). It is difficult to determine how
KBOs wind up
traveling in pairs. They may have formed that way, born like
twins, or may
be produced by collisions where a single body is split in two.
Ever since the first KBO was discovered in 1992, astronomers have
wondered
how many KBOs may be binaries, but it was generally assumed that
the
observations would be too difficult for most telescopes. However,
the
insights to be gained from study of binary KBOs would be
significant:
measuring binary orbits provides estimates of KBO masses, and
mutual
eclipses of the binary allow astronomers to determine individual
sizes and
densities. Assuming some fraction of KBOs should be binary --
just as has
been discovered in the asteroid belt -- astronomers eventually
began to
search for gravitationally entwined pairs of KBOs.
Then, finally, exactly a year ago on April 16, 2001, Veillet and
collaborators announced the first discovery of a binary KBO: 1998
WW31.
Since then, astronomers have reported the discoveries of six more
binary
KBOs. "It's amazing that something that seems so hard to do
and takes many
years to accomplish can then trigger an avalanche of
discoveries," says
Veillet. Four of those discoveries were made with the Hubble
Space
Telescope: two were discovered with a program led by Michael
Brown of the
California Institute of Technology in Pasadena, Calif., and two
more with a
program led by Keith Noll of the Space Telescope Science
Institute in
Baltimore. The sensitivity and resolution of Hubble is ideal for
studying
binary KBOs because the objects are so faint and so close
together.
The Kuiper Belt is one of the last big missing puzzle pieces to
understanding the origin and evolution of our solar system and
planetary
systems around other stars. Dust disks seen around other stars
could be
replenished by collisions among Kuiper Belt-type objects, which
seems to be
common among stars. These collisions offer fundamental clues to
the birth of
planetary systems.
-end-
Electronic image files, animation, illustrations and additional
information
are available on the Internet at:
http://oposite.stsci.edu/pubinfo/pr/2002/04
http://oposite.stsci.edu/pubinfo/latest.html
http://oposite.stsci.edu/pubinfo/pictures.html
http://hubblesite.org/go/news
============
(4) ROCKS TWIRL IN REMOTE TWO-STEP
>From Nature Science Update, 18 April 2002
http://www.nature.com/nsu/020415/020415-8.html
One lump of rock is revealed as two in the distant Kuiper belt.
PHILIP BALL
The stand-offish dance of two asteroids at the outer reaches of
the Solar
System is captivating astronomers. The two rocky objects,
discovered locked
in mutual orbit, could tell us about the properties of the
far-flung Kuiper
belt.
Christian Veillet and his team1 studied an object called 1998
WW31 in the
Kuiper belt, a sparsely populated region of space beyond the
orbit of
Neptune. The object was previously thought to be a single rock.
One is in fact two, the team found, using images obtained by the
Canada-France-Hawaii Telescope in Hawaii. And the pair follow an
unusual
elongated, ellipse-shaped orbit which keeps them 20-40,000 km
apart. This is
considered a very distant partnership for a 'binary object'.
The circling pair, which complete a rotation every 570 days,
might offer
some vital clues to the composition of rocks in the Kuiper belt.
Its extreme
distance makes resident objects difficult to study.
If one of the circling bodies eclipses the other, the pair's size
could be
estimated and hence their density. Understanding the composition
of material
in the Kuiper belt - which is thought to contain rubble left over
from
planet formation - might help to discriminate between different
explanations
for the formation of the Solar System.
Kuiper-belt binaries are hard to spot, because two small bodies
can appear
as a single fuzzy blob of reflected sunlight at such long
distances. Even if
two spots are seen, several images are needed to rule out the
possibility
that they are two adjacent stars along our line of sight. Veillet
and his
team carried out such careful analyses before they could
confidently claim
that 1998 WW31 is indeed a binary.
The elliptical orbit is very different from that of the best
known
partnership in the Kuiper belt: the outermost planet Pluto and
its moon
Charon. The binary systems known in the asteroid belt between
Mars and
Jupiter also stick closer together than 1998 WW31.
The new discovery challenges existing theories of how two
asteroid-like
bodies can become bound together by their gravitational pull.
Researchers
are not yet clear why the two rocks have not been ripped apart by
interactions with other bodies in the Kuiper belt.
References
Veillet, C. et al The binary Kuiper-belt object 1998 WW31.
Nature, 416, 711
- 713, (2002).
© Nature News Service / Macmillan Magazines Ltd 2002
================
(5) AUSTRALIA PREPARES FOR ASTEROID SCAVANGER'S OTHERWORLDLY
CARGO
>From Space.com, 17 April 2002
http://story.news.yahoo.com/news?tmpl=story&cid=96&ncid=96&e=2&u=/space/20020417/sc_space/australia_prepares_for_asteroid_scavanger_s_otherworldly_cargo
By Leonard David
Senior Space Writer, SPACE.com
With a Japanese space mission planned to bring asteroid samples
back to
Earth and drop them on Australia, the government down under is
studying
what's up in regards to possible contamination and quarantine
procedures
that might be needed.
Biosecurity Australia, a group within that the country's
Department of
Agriculture, Fisheries and Forestry, is developing quarantine
protocols for
an exotic import from space.
Meanwhile, now being readied for launch is the Mu Space
Engineering
Spacecraft-C, or MUSES-C for short. The project is under the wing
of Japan's
Institute of Space and Astronautical Science (ISAS).
MUSES-C will ride atop an M-V booster roaring out of the
Kogoshima Space
Center, likely in November or December. The multi-year mission is
dedicated
to collecting asteroid surface samples, then returning those
specimens to
Earth in June 2007.
The proposed landing site for the precious asteroid pickings is
Woomera, in
South Australia.
Asteroids are considered time capsules, retaining clues and
insight into the
early formative stages of our solar system. By hauling back the
goods from
such bodies, scientists can intensively study the celestial stuff
using an
array of laboratory gear.
Safeguard against the unknown
Biosecurity Australia will take part in a government review of
landing
asteroid samples on its soil, an assessment involving Environment
Australia
and the country's Department of Defense (news - web sites).
"Although the risk of the asteroid sample containing any
living entity is
likely to be negligible, quarantine procedures may still be
necessary," said
Peter Hewitt, Biosecurity Australia's principal veterinary
officer. "This is
to safeguard against the unknown, yet remote, possibility of life
forms such
as micro-organisms that could be a threat to human, animal and
plant health,
and the natural environment," he explained in a Biosecurity
Australia
newsletter.
Once launched, Japan's MUSES-C is targeted to rendezvous in
mid-2005 with
asteroid 1998 SF36. The orbit of that mini-world crosses that of
Earth,
making it relatively easy for the space probe to reach the
asteroid, snag
some samples, then high-tail it back to Earth.
Horn of plenty
After many tests and designs, ISAS engineers have come up with a
MUSES-C
sampling device.
The spacecraft will carry a horn that will be brought up to the
surface of
1998 SF36 as MUSES-C makes a close approach to the asteroid. A
small
pyrotechnic charge will then fire a bullet into the surface and
fragments of
the impact will be captured by the horn and funneled into a
sample
container.
Nobody knows for sure the physical make-up of the targeted
asteroid. Perhaps
a gram or more of sample surface material will be collected.
MUSES-C will use a solar electric propulsion system on its
four-year
round-trip flight. Other challenging aspects of the sample
collecting
mission include autonomous navigation and guidance for approach,
rendezvous
and landing on the asteroid; snagging and storing the samples in
a capsule
and sealing it; and having the return capsule survive a
blistering reentry
through the Earth's atmosphere, then parachute to a touchdown.
Biosecurity Australia's Hewitt said that any quarantine
procedures
established would draw heavily from earlier work done in America.
The U.S.
National Research Council (news - web sites)'s Space Studies
Board has
completed a detailed risk analysis of sample returns from
planetary
satellites and small bodies within the Solar System, he said.
Next page: How to avoid an Andromeda strain
Type-S asteroid
Hewitt told SPACE.com that the risk analysis is being conducted
in response
to a formal access request from Japan's ISAS. Asteroid 1998 SF36
has been
identified and categorized into a type-S body. That is, based on
current
Earth-based spectral analysis, the rocky mini-world is an
undifferentiated
metamorphosed asteroid.
"Despite the perceived low risk and absence of trade
implications, public
consultation may be undertaken because of the likely public
interest and
concern with the proposal. This risk analysis is being
coordinated in
consultation with Environment Australia," Hewitt told
SPACE.com.
"Because detailed risk analyses into sample returns from
planetary
satellites and small solar system bodies have already been
undertaken, the
primary role of our risk analysis is to review and adapt this
risk analysis,
as appropriate, to ensure Australia's quarantine concerns are
addressed,"
Hewitt said.
Factors considered
Hewitt said that factors considered in the analysis include:
Whether liquid water, energy sources or organic matter, which are
necessary
for life, are present on the asteroid (all indications are that
the asteroid
has none of these);
Extremes of temperature and radiation exposure (both high
temperatures and
prolonged radiation levels indicates that any life, if it ever
existed on
the asteroid, is unlikely to exist now);
The lack of evidence of life forms in meteorites that enter
Earth's
atmosphere daily; and
The likelihood of an extraterrestrial life form surviving in an
Earth
environment;
In addition to the above factors, Hewitt added, Biosecurity
Australia also
has to consider the significance of evidence that
cross-contamination of
asteroids with material from other sources occurs. Also, the
group will
consider environmental exposure with the sample material at the
landing site
should the sample container breaks open on impact, say from
failure of the
sample capsule's parachute to deploy.
Lastly, Biosecurity Australia will delve into the effects of
extraterrestrial microorganisms on established microbial
communities, if
such organisms do exist, and whether such biology could find an
eco-niche
here on Earth suitable for growth.
Prudent policy
"Although the overall risk of adverse effects from a
returned sample from an
type S undifferentiated metamorphosed asteroid is likely to be
extremely low
to negligible, there are still some gaps in the information
necessary to
accurately determine that risk. Although available data will
continue to
expand over time, much of the information required will only be
obtained by
sample return missions. Until such additional information is
available, it
may be prudent to consider appropriate risk management procedures
for return
samples from small Solar System bodies," Hewitt said.
The risk analysis currently being undertaken by Biosecurity
Australia,
Hewitt said, will consider what, if any, appropriate risk
management
procedures are necessary especially in the event of a breach of
the sample
container.
The draft risk analysis is going through its final stages of
development and
hopefully should be available for public comment in a few months,
Hewitt
said.
Copyright 2002, Space.com
==============
(6) WALKING WITH DINOSAURS?
>From BBC News Online, 17 April 2002
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1935000/1935558.stm
Primate ancestor lived with dinos
The common ancestor of humans, monkeys, apes and other primates
may have
arisen much earlier than previously thought.
New research suggests the animals from which humans could have
emerged were
living in the tree tops 85 million years ago, when the dinosaurs
still ruled
the Earth.
Until now, the widely accepted date was 65 million years ago,
about the time
when the dinosaurs died out.
But a team of scientists in Britain and the United States has
analysed gaps
in the fossil record and come up with a new figure, some 20
million years
earlier. It means the whole story of primate evolution may have
to be
rewritten.
The new theory challenges the idea that primates were unable to
make their
mark on the planet until after the demise of the dinosaurs.
It also suggests that continental drift played a role in how
primates
evolved in different parts of the world. It even has implications
for our
own descent - the first humans may have appeared about eight
rather than
five million years ago.
Jigsaw puzzle
The research, which was revealed in the scientific journal
Nature, is based
on a statistical analysis of evidence from the fossil record.
According to a computer model, no more than 7% of all primate
species that
ever existed have been dug up.
Co-author Robert Martin, of the Field Museum in Chicago, US, said
current
interpretations of primate and human evolution were flawed
because
palaeontologists had relied too heavily on direct interpretation
of the
known fossil record.
He said: "Our calculations indicate that we have fossil
evidence for only
about 5% of all extinct primates so it's as if palaeontologists
have been
trying to reconstruct a 1,000-piece jigsaw puzzle using just 50
pieces."
It weighed just a few pounds and dined on fruit and insects.
The females gave birth to a single offspring, which clung to
their fur.
Co-author Dr Christophe Soligo of the Natural History Museum in
London, UK,
said the new work put specific events within primate evolution
into a very
different context.
"The world 85 million years ago was very different to the
world 65 million
years ago," he told the BBC.
"What we demonstrate is that modern orders of mammals
appeared well before
dinosaurs disappeared so the initial divergence of modern orders
of mammals
cannot be the result of the extinction of the dinosaurs."
Copyright 2002, BBC
============================
* LETTERS TO THE MODERATOR *
============================
(7) AGE OF EMPEROR HAWAII CHAIN
>From Hermann Burchard <burchar@mail.math.okstate.edu>
Dear Benny,
in an AGU 2002 Spring Meeting Abstract S32A-11, R. D. Brown
(CCNet
2002-4-17) posits "the Hawaiian impact site circa 65
Ma". The oldest
Emperor Seamounts having been dated to over 80 Ma by basalts from
DSDP Hole
884 on the Detroit Seamount, 2nd oldest, this hypothesis may be
considered falsified. The oldest of the mounts, Meiji,
immediately adjacent
to Kamchatka, is buried under a great apron of sediment and could
not be
dated (DSDP hole 192).
Rather, the Emperor-Hawaii chain appears to be contiguous with
the Sibirian
traps, which according to long-time CCNet contributor Adrian
Jones of UCL in
a recent CCNet note 2002-4-8 should be reconsidered as related to
a possible
250 Ma end-Permian impact event. There is a brief hiatus
due to subduction
at the very cusp of the Aleutian-Kamchatka trenches, surely no
conincidence.
Except for a missing subducted piece, a majestic 10,000 km
volcanic
structure stretches from Kilauea to Kamchatka (under the Sea of
Okhotsk?)
and on, from Magadan continuing toward the West to the
Urals. The amount of
magmas extruded in the West Sibirian basin and the adjacent South
Kara Sea
exceeds all of the Sibirian traps.
In this context, it is remarkable that the ancient mountains of
the Urals,
having already been peneplained by Permian times, seem to have
been
rejuvenated (reheated and excavated) just at that epoch of 250
Ma. Their
unique structure in W-E section (W: Sedimentary rocks of Permian
age --
Perm is a city on the W flank. E: Steep descent of interbedded
lavas to the
featureless lava plains of W Sibiria) and the double bend around
the two
terrestrial maria of the W Sibirian Plain (2000 km diameter) and
the S Kara
Sea are all highly suggestive.
Adrian Jones also considers possible mechanisms for impact plume
formation.
Here, Steve Sparks of Bristol University has worked out an
interesting
theory of pulsating eruptions due to frothing of magmas under
pressure
relief melting that could help to find answers. As remarked by
many authors, mantle viscosity is very high; this would lead to
pulse
intervals measuring in times of several 100 Ka (this qualifies as
really
more than a theory, as he has conducted experiments in support
and can cite
known resurgent calderas as empirical evidence). The
frothing can cause
great explosions at each cycle, with large volumes of magma
ejected from the
mantle and removed, preparing for the next frothing cycle due to
the
resulting reduction of overburden. Hence, this model would also
allay
concerns brought up by Jay Melosh that impacts don't cause mantle
magmas to
rise from sufficient depths (see his recent abstract posted on
CCNet). The
observed depths of only about one tenth of crater diameters for
example at
Chicxulub should be seen in the context of plate tectonics: The
bottom of
the crater is no longer positioned over the original mantle
impact site, but
has slipped off toward the W by perhaps 2,000 km.
Regards,
Hermann
===========
(8) RIO CUARTO IMPACT DATE
>From Yvan Dutil <yvan.r.dutil@ca.abb.com>
Dear Benny,
Can someone provide the reference for the quoted impact date of
2360 BCE for
the Rio Cuarto impact. From what I know it comes from an
interpretation of
ancien text but I have been unable to find any published paper
about this.
Yvan Dutil
MODERATOR'S NOTE: Ed Grondine's date is pure speculation and not
based on
any hard evidence. I understand that Pete Schultz (Brown
University) is
currently on a new field study in Argentina, trying to refine the
dating of
the Rio Cuarto impact which is presently thought to have occurred
during the
last 5,000-10,000 years. BJP
==========
(9) FUTURE MARTIANS WOULD RELISH IMPACTS
>From Oliver Morton <abq72@pop.dial.pipex.com>
Jens Kieffer-Olsen <dstdba@post4.tele.dk>
wrote:
>WE WILL BEFORE THE END OF THIS CENTURY TRACK THE ORBITS OF
200 MILLION
>ASTEROIDS LARGER THAN 100m
>
>This target is a requirement if the exploration of Mars is to
become a
>reality in the 22nd century. An asteroid detection scheme for
Mars is a
>prerequisite, if astronauts are to dwell there safely for one
year, a
>duration often proposed for the inaugural flight.
>
>A permanent settlement on Mars would require an asteroid
deflection
>capability similar to that defending Earth. And with a
much higher
>frequency of being put to use.
>
>Considering the large number of asteroids crossing the orbit
of Mars it
>seems natural to not limit our target, except to asteroids in
orbits
>entirely outside that of Jupiter.
>
The concern for future Martians seems somewhat overdone. There
will be very
few of them, if any. They will probably be located at only a
couple of
permanent sites. They will have back-up supplies to a degree that
terrestrial civilisation does not (partly becaus ethey can and
partly
because failure of environmental systems will be an openly
discussed
engineering risk). They will tend to live undergound, or at least
have
sturdy bunkers, due to radiation risk. They will also have
demonstrated a
willingness to accept higher levels of risk than most of us.
Moreover, this hardy, mobile and risk-tolerant few will be on a
planet where
the most dramatic effects of impacts -- those mediated by the
atmosphere and
the oceans -- will be pretty negligible, given the near lack of
the first
and the total lack of the second. No tsunamis, and no global dust
storms any
worse than the global dust storms that will already be part and
parcel of
martian life. I suspect that largest risk posed by an impactor on
mars would
be direct blast effects, and i would guess that on at least 99.9%
of the
planet's surface there will be no-one to feel them.
Indeed if there are humans on Mars in the twentyfirst century, it
seems more
likely that they would relish an impact than try to avert it.
Their presence
will in all likelihood be motivated at least in part by science,
and the
opportunity to study the near-term after-effects of an impact,
especially if
it were to melt significant ground ice or puncture an aquifer,
would be of
great astrobiological interest. I would suggest that the martians
would in
fact be more likely to deflect otherwise harmless asteroids
*towards* Mars
so as to provide impacts for study than to deflect impactors
away.
Of course, such a project would mean they would need a good
register of
potential impactors -- so maybe they will agree with Jens's
conclusion as to
the need for a census, if not for his reasons.
best
oliver
=============
(10) MARTIANS WILL ENJOY REPRESENTATION WITHOUT TAXATION
>From Jens Kieffer-Olsen <dstdba@post4.tele.dk>
I don't think you would want to stir up more red dust than what's
unavoidable. In the far future when terra-forming the planet
comes on the
agenda, and if the elements required for an atmosphere cannot be
extracted
from materials in its interior, then it is plausible that objects
such as
comets will be directed towards Mars, but I certainly hope that
all
scientists will have been evacuated beforehand.
> Of course, such a project would mean they would need a good
register
> of potential impactors -- so maybe they will agree with
Jens's
> conclusion as to the need for a census, if not for his
reasons.
Martians will not need independence any time soon. Rather they
will enjoy
representation without taxation!
Cheers
Jens Kieffer-Olsen, M.Sc.(Elec.Eng.)
Slagelse, Denmark
===========
(11) APPRECIATION FOR CCNet
>From Don Stockbauer <donstockbauer@hotmail.com>
Dear Dr. Peiser,
Thanks very much for moderating the CCNet. You definitely find
articles that
I would not find on my own.
One of them dealt with the effort to force people through
international law
to start thinking about impactor deflection/mitigation plans
rather than
banking on the long odds that nothing will happen. It's been my
empirical
observation since monitoring this subject that nothing will get
done about
it until a set of very interesting numbers pop-up from the
machines. At that
point hopefully there will enough lead-time to actually do
something, the
amount of which could be considerably lengthened by being
proactive rather
than shutting down discussion. Seen from a cybernetic point
of view,
discussion (feedback) never hurts. Lack of feedback leads
to termination,
just as falling asleep at the wheel does. But then there is also
the effect
of everybody getting sick of the whole thing and closing
discussion anyway.
Me, I'm approaching it all scientifically and keeping my fingers
crossed.
Another interesting article was the one on how anyone can use
SOHO data to
discover new comets. This is a truly revolutionary concept.
Perhaps someday
all knowledge will be put online available for anyone to use,
rather than
being sequestered behind institutional proprietary walls.
That in
itself would, IMHO, be the largest factor in ushering in the
Global
Brain/Social Superorganism, the adult version of the infant
that's been
self-organized at this point.
Don Stockbauer
donstockbauer@hotmail.com
===========
(12) GREAT BALLS OF FIRE
>From Bob Kobres <bkobres@arches.uga.edu>
With regard to objects crossing the Sun's disk, I favor Duncan's
notion that these are generally objects within Earth's
[extended] atmosphere. I think that we still have a great
deal to learn about how impacting debris interacts with our
planet's
atmospheric and electromagnetic layers. It seems likely to
me that the chemical nature of the material involved could
play a large role in how the energy and debris disperses within
the atmosphere. If chemistry does play a larger than
supposed role during impact events then assessing risk by object
size is misleading at best. The potential to produce
electro-magnetic pulse (EMP) as well as secondary fireball or
ball lightning phenomena is not well understood but seems
to have been observed. Such factors are important when
trying to guess the damage that a Tunguska type event could
visit upon an electronic-gadget dependent population.
Below are some snippets from various observations of
fireballs. Particularly interesting is one, six miles in
diameter,
captured by camera eight seconds (minimum) after the photo taker
was first made aware of the phenomenon via a bright
flash! Photo here:
http://abob.libs.uga.edu/bobk/chant/fballs/
[DjVu format]
http://abob.libs.uga.edu/bobk/korea/
[fig. 12]
Later.
bobk
From:
http://abob.libs.uga.edu/bobk/fball/chifball.djvu
[The actual text snippets below were omitted from the mailing.
bk]
GLEANINGS FROM THE MAILS
CHICAGO CELESTIAL VISITOR.
THE BOLT OF FIRE THAT FELL ON. THURS-
DAY -- SIMULTAINEOUS STROKE OF
LIGHTNING THAT BROKE MUCH GLASS
>From the Chicago Tribune, April 10 [1879]
The lightning which accompanied the rain
yesterday evening, or rather what is commonly
called a "bolt" of it, created great consternation,
and caused considerable damage at two of the four
corners of South Park avenue and Twenty-fourth-
street At the time of the striking, what looked like
a large ball of fire was seen to burst in the air, and
to this was laid the blame by many. But the "ball"
was undoubtedly a meteoric stone. It seemed about
as large as an ordinary tumbling hoop, and was sur-
rounded by what had the appearance of smoke
The report was as loud as that made by a 10-
pound gun, and the concussion nearly threw
one man off his feet. A shower of frag-
ments fell on both the streets named but
hurt no one. The lightning ran into Downer & Be-
mis's office, and Col. H. C. Nutt's residence opposite,
simultaneously, on a telephone wire, setting fire to
the former and playing havoc with the glass in the
latter. There was a quantity of paint, some carpet
&c., in the second story of the office, and the stuff
was burning briskly before the people down stairs
knew anything was wrong. Passers-by on side-
walk saw the, flames. and an alarm was given from
Station No. 121. About $200 damage was done to
the building and furniture, which are insured for
$6,500--$3,000 In the Hoffman. of New-York, and
$3.500 In the Manufacturers' of Boston.
The electric fluid entered first the library of Col.
Nutt, where his telephone was located. The ground
wire, as is always the case, was attached to the gas
bracket. The lightning, however, instead of finding
its way quietly to the earth, went on what might be
called a spree, and, in following the gas-pipe, was so
reckless that it smashed everything in glass within.
And, apparently, out, of its reach. The globes on the
chandeliers in the parlors were displaced and splin-
tered on the carpet; the front window panes on the
first floor were blown into the yard. and the frag-
ments of the transom light over the door filled the
vestibule. In the library the telephone wires were
burned off, the walls were blackened in spots and
potions of the plaster were torn off, while the book-
case received a worse shaking-up than an express-
man would have given it on moving day. Even the
goblets on the dinner-table in the basement were
broken. The crockery alongside was undisturbed,
though the cook in her fright. broke a plate. The
gas meter was ripped up and the gas caught fire, but
was quickly put out. A rough estimate of the dam-
age was $150.
The Colonel and Mrs. Nutt had a very narrow
escape. Three minutes before their house was in-
vaded in this summary way they were talking
through the telephone with a friend on the West
Side. Mrs. Nutt had just seated herself in the bay-
window in the adjoining room when she heard the
noise. and. as it was she experienced a shock, which
she has not yet fully recovered from, her left side--
the one next the window, the glass in which was also
broken--feeling numb. Some are of opinion that
the meteor struck this bay-window--it seemed to from
were they stood, but this was doubtless an optical
illusion, since if it had done so the house and its in-
mates would have known of it. Pieces of the meteor
which were picked up resembled "clinker," or slag,
and, while dark outside, are almost white in the
centre. The falling of a meteor and the striking of
lightning at the same moment in the same place is of
rare occurrence. but such a thing is known to have
taken place in the past. Nothing out of the way oc-
curred in any other part of the city.
>From the Chicago Tribune, April 11.
The meteor that exploded near the corner of
Twenty-fourth-street and South Park-avenue, in
this city, last Wednesday night, was the subject of
much comment yesterday. Early In the morning a
number of curiosity hunters were out, seeking
for fragments; and they found a great quantity,
probably as much as two bushels in the aggregate.
The writer made a tour of observation last night,
and succeeded in procuring several specimens from
H. Spruance. Esq., and Col. H. C. Nutt, the later gen-
tleman being the one whose house took fire on the
interesting occasion, as already published in the
Tribune. These pieces ranged all the way down
from the size of a double fist to the smallest bit
that the unscientific collector would care to pick up.
A couple of these pieces were weighed in air and
then water. giving their specific gravities respec-
tively as 2.3 and 2.1.
A meteor that would contain a "barrel" of matter
must be of respectable size, but there is good reason
to believe that this meteor was very much larger than
that. A comparison of the observations of Julian
Kune, Esq., with those of Col. Nutt warrants the
Belief that the principal explosion occurred over the
lake, at some distance from the shore, and that the
pieces picked up in the vicinity above named formed
only a small part of the body that passed into the
earth's atmosphere a few seconds before the explo-
sion was witnessed. That smaller portion was
driven off obliquely and probably again separated
into still smaller fragments after it passed the shore
line. The explosion certainly occurred more than
half a mile from either of the two observers, and
their description of the intense light and apparent
size indicates that the mass could not have been less
than two or three yards in diameter, even after
making full allowance for apparent enlargement
due to great brilliancy. It is very fortunate in-
deed, that no one came into collision with this little
world, or any part of it, as its fragments fell over a
pretty well populated part of the city.
There was no time last evening for analysts of the
Fragments, and in the absence of that it would be
Idle to indulge in guesses, which might prove to be
wide of the mark. The small specific gravity,
scarcely equal to that of the average rock, even in
the specimens which seemed to be fused solid, argues
an earthy constitution; but does not prove that Iron
did not enter largely into the composition of the
original meteor. The slag-like texture of some
pieces, and the more cinder-like character of others.
show, however, that all the pieces found did not
come from the exterior of the mass. All are fused
as if passed through an intense furnace heat, and
some of the fragments were still very hot when
picked up by the finders. The noise of the explo-
sion was estimated by one who has been in the ser-
vice as about equal to that of a 12-pounder at a dis-
tance of 250 yards.
The Great Meteor of March 24, 1933, by H. N. Nininger (1934)
http://abob.libs.uga.edu/bobk/chant/fballs/
In a ranch house located in a narrow valley, some 25 miles
southwest
of Clayton, New Mexico, Chas. M. Brown, locally known as Charlie,
foreman on the Lyon ranch, was just ready to sit down to
breakfast as
the clock struck five on that eventful morning. The meteor
flashed,
lighting up the sky like midday.
The No. 2 A Brownie folding pocket kodak lay on the radio to the
right and back of Charlie's breakfast chair. It was not there for
any
special purpose only that in a small crowded ranch house it had
to be
somewhere and this chanced to be its place. It was seldom used
but
happened to have a partially exposed roll in it that morning. The
chores
had been done and breakfast was called. Brown approached the
table;
but just as he did so the sky suddenly lighted.
At the first flash he grabbed the kodak and made for the door,
open-
ing the Brownie as he went. When he reached a point about eight
steps
from the door he was clear of the trees. He trained the
instrument on
the approaching meteor and snapped the shutter. When he again
looked
up the meteor was disappearing over the house.
I had Mr. Brown go through the motions again just as he had done
that morning, and found it required eight seconds for him to get
the
picture, from the time the light first flashed.
[. . .]
After going over all of the evidence, I am led 'to believe that,
subse-
quent to the bursting depicted by Bishop and other witnesses, we
had at
least a double and perhaps still later a multiple meteor.
According to
our survey the spherical cloud which was sketched by Bishop is
the same
as that photographed by Brown. It will be noted that there are
two
prominences on the forward end of the spherical ball in the Brown
pho-
tograph. It seems reasonable to conclude that these are the
points from
which two fragments are about to emerge.
A careful study of the Brown photograph together with a large
num-
ber of related data was made by Mr. J. D. Figgins, Director of
the Colo-
rado Museum of Natural History, and the writer. We conclude that
the most satisfactory explanation of this photograph is to be
found in
assuming that the meteor was produced by a huge meteorite of
unsym-
metrical form such that when it encountered the atmosphere it
produced
results analogous to those produced by an irregularly shaped
pebble
thrown into the water, describing the very erratic course
recorded in
the more distant portion of the Latham photograph. As it
recovered
from the first shock of impact, it acquired a certain equilibrium
travel-
ing in the spiral course so graphically shown in the Brown
photograph.
By the time the last explosion occurred the mass had been so
mutilated
by its aerial conflict that it was rent asunder, producing the
two missiles
depicted by Bishop, as fireballs which indeed they continued to
be for
many miles.
The large incandescent spheroid shown in the photograph presents
a
difficult problem for interpretation. As has been previously
stated, this
picture actually represents an object no less than six miles in
diameter.
What was the nature of this spheroid?
[. . .]
The texture of the stones from this fall is such that it would
have
disintegrated rapidly when subjected to great vibration or
strain. In-
deed, it appears to be like volcanic dust or tufa more than like
anything
else. The immense cloud which continued to float in the sky long
after
all luminescence had disappeared was doubtless composed of dust
from
the disintegrated meteorite.
[. . .]
These reports made it very easy to arrive at a fair understanding
of
its general course; but when it came to a matter of definitely
plotting
it the case was more difficult. Disagreements among even the best
ob-
servers as to the exact location and direction persisted in spite
of all
efforts to harmonize 'them. A few days later, when Dr. Strong's
report
had been received stating that "it wobbled in its
course" matters began
to clear up and when finally the photographs by Brown and Latham
arrived, the warped train of the meteor was definitely
established.
>From the start, some few persons who happened to see the
meteor
from its very earliest appearance had insisted that it changed
its course.
While at first this seemed improbable we now know that such was
the
case. Near the beginning of its visible course it is shown in the
photo-
graph, Figure 4, and the drawing by Martinez, to have borne
strongly
to the southward and then 'turned toward the west, following
subse-
quently a zigzag course over a line which bears about 12 1/2ø
southward
from a due east-west line. (See map.)
[. . .]
As with all of the meteors which the writer has investigated,
there
were many people who in this instance reported hearing a swishing
or
whining noise at the instant of the fireball's passage. Of course
it is at
once evident that a sound from the meteor passing 50 or 100 miles
from an observer would require minutes to reach him, yet one
meets
with this same story so frequently as to raise the question
whether there
may not be a method of sound transmission at the velocity of
ether
waves. Dr. E. H. Sellards has called attention to this same
problem in
his description of the great meteor of June, 1923. The
explanation
usually offered is the psychological one that observers
unconsciously as-
sociate the meteor with the passage of an ordinary rocket and
that their
memory of the event also associates the sound of the rocket's
passage,
assigning it as an accompaniment of the meteor's flight. However,
re-
ports of sound simultaneous with the passage of the meteors come
so
frequently and in many cases under circumstances which seem to
justify
serious consideration of the problem. In several instances
witnesses
have testified emphatically regarding various meteors, that such
a swish-
ing noise first drew their attention and led them to. seek its
source when
as yet buildings or other objects hid the meteor from view. One,
of
course, feels that the unexpected lighting of the landscape may
have
been the real stimulus which aroused them and that confused
recollec-
tions led them later to assign as the cause the sounds which
really ar-
rived later. However, to assign such an explanation in many
instances
which have come under my personal notice seems rather
presumptuous.
While the present paper has been in preparation the writer was
given
the following account by Mr. J. 14. Bruer of Crawford, Nebraska,
who
witnessed the daylight fall of August 8, 1933, at 10:20 A.M.
Mr. Bruer is an implement dealer whose building faces the south
and
the door which is about 10 feet square was standing open that
morning.
He was talking to a customer, while uncrating some implements,
about
22 feet (measured by the writer) back from the open door when he
heard what he supposed was the "banking of an
aeroplane." Being
somewhat interested in aeronautics he said to the customer,
"I wonder
who that fellow is," and started walking toward the door. (I
had him
repeat this action while holding a watch on him and concluded it
was
about three seconds from the hearing of the first sound until he
reached
a point where he could see the meteor.) When he reached a point
near
the door he expressed his surprise and called the customer to
come and
see; for he beheld a huge fireball moving across the sky. It was
almost
due south when first seen and our survey, later completed, proved
that it
was about 100 miles away, moving from S.S.E. to N.N.W. It
vanished
about 20. miles S.W. from where Bruer was standing.
After standing for perhaps a minute looking at the cloud left by
the
meteor and commenting upon the strange event they walked back and
he resumed his work, whereupon they were again startled by a
rumbling
sound which resembled that made by the passing of a huge army
truck
with solid rubber tires (such a truck from the nearby fort passed
in
front of his building daily).
Mr. Bruer is a man of intelligence and one who is not at all
excitable
and it can hardly be doubted that he actually heard two different
sounds
as above described. That both came from the meteor cannot be
proved
but all inquiry failed to reveal that any aircraft was afloat at
that hour
in the vicinity of Crawford or to bring forward any other
explanation
of the strange sound. Several widely scattered observers reported
the
hearing of similar sounds at the moment of passage while others
failed
to record any sound whatever. The above is one of many such
instances
which have led the writer to believe that there may be, in
connection
with meteors, ethereal as well as aerial propagation of sound.
Without exception, those who have reported this peculiar phenome-
non describe the sound as a sort of hum, whine, or a swishing
noise, oc-
casionally comparing it with the noise produced by thrusting hot
iron
into cold water. Seldom has there been indicated any resemblance
to the
detonations which arrived later. This distinctive character of
the sound
would argue against the idea of confused recollections above
mentioned.
I prefer to leave the matter as an open question as to whether
there
may be propagation of sound by more rapid means than that with
which
we are acquainted.
[. . .]
Due to the very erratic course which the projectile was traveling
dur-
ing its visibility the location of the fall is a very difficult
matter to de-
termine. The course is indicated on the accompanying map and the
angle
of descent was approximately 8.5 degrees with the horizontal at
the
vanishing point. If we allow that the course subsequent to the
time
when the light was extinguished ended midway between the vertical
and
the point where the projected visible path would meet the earth,
and
assume a height of 121/2 miles for the vanishing point, then the
landing
should have taken place somewhere about 20 miles west and 5 miles
south of Wagon Mound, New Mexico, and either north or south of
this
point, depending on the deviations from a regular course. As a
matter
of fact it has been impossible to determine satisfactorily the
height at
which the light disappeared, which may have been as much as 18
miles.
This renders the location of the fall quite questionable.
Practically all
of the country west of Wagon Mound is sparsely settled and much
of
it is very rough, hence the finding of the fall will be very
difficult.*
Just before going to press a trip along the line of flight some
35 miles
back from its point of disappearance resulted in the recovery of
a few
fragments from this great fireball, one of which had been picked
up
immediately after its fall. The texture of the stone, which is
very fri-
able, renders it unlikely that any considerable mass landed
intact.
The location of these fragments proves that our survey had
correctly
located the path of flight.
*Since establishing the height at which the fireball vanished as
17 miles, the
location of the landing of the main mass (if such a mass landed)
should be con-
siderably farther west.
From:
http://www.meteoritesales.com/met_k.htm
Note date and location.
Kagarlyk....................................49'52' N., 30'50' E.
Kiev district, Ukraine, USSR,
Fell 1908, June 30, 0700 hrs
Stone. Olivine-hypersthene chondrite (L6).
After the appearance of a fireball, followed by detonations, a
stone of
1.9kg was found 60km from Kiev .
See also:
http://www.meteorite.narod.ru/proba/katalogi/katalog1.htm
From:
PHILOSOPHICAL TRANSACTIONS:
MATHEMATICAL, PHYSICAL AND ENGINEERING SCIENCES
Phil. Trans. R. Soc. Lond. A (2002)
Ball lightning
PAPERS OF A THEME COMPILED AND EDITED BY J. ABRAHAMSON
(&127) 2001 The Royal Society
On the energy characteristics of ball lightning
BY A. V. BYCHKOV, V. L. BYCHKOV AND JOHN ABRAHAMSON
Pages 104-105
3. C. Egely (1987) Case 222. Observer: Pecs. Salyi Janos
It happened in clear, bright, sunny weather in July, 1972. At
noon most of the
workers of our factory were having lunch but several of them
stayed in the factory
building. Suddenly they caught sight of a bright sphere of the
size of a football
rolling along the lightning conductor. It was accompanied with a
hissing sound and
was coloured transient between pink and yellow. It had come
through the long glass
window on the roof. Then it vanished in the water-pit with a
tremendous crack,
at the outer corner of the building, next to the lightning
conductor. Afterwards
the air felt rich in ozone. The water disappeared from the pit,
leaving no trace
behind. Though already totally dry the pit was still steaming
after half an hour. The
phenomenon was seen by about 30 people for approximately 8-10 s.
The velocity of
the bright sphere was about 3-5 ms\-1. The sound it emitted was
similar to that of
a supersonic plane, that is it was a hissing, whistling sound.
The pit had originally
contained about 120 l of water since it had not been full, only
up to 2/3 part. My
colleagues examined it thoroughly but no water was splashed on
the walls, and all
the water evaporated. It was noted that it was steaming even a
long time after the
event. None of my colleagues felt either any heat radiated or
perceived an impulse.
The windows did not vibrate though a bad ringing was in their
ears because of the
blast of the explosion. One of my colleagues, called Bela
Trischler, was just looking
out of the window when the ball lightning fell into the water-pit
and he saw not only
the steam but also that some leaves of grass round the pit caught
fire and burned
down eventually. The ground cable was not damaged at all.
8. M. T. Dmitriev, B. L Bakhtin and V. L Martynov (1981).
Ball lightning was observed at 11.20 p.m. on 24 August 1978 in
the city Khabarovsk
in the area of Khasan street during a strong rain. Suddenly a
sharp whistle was heard.
It resembled the sound of a jet engine and was accompanied by a
strong crackling.
It became very light as during a day. Then over the building of
the cinema theatre
'Zarya' appeared a ball lightning of 1.5 m diameter with
bright-orange colour. Sparks
were coming out of it. Then the ball lightning began to descend,
went to the Earth's
surface through the branches of a tree, then for a moment it was
shining over some
area of the soil and ascended. It ended with a strong explosion,
then it became dark
and quiet. The ball lightning existed totally about 1 minute. It
was observed by
many people, including one of the article's authors. The
possibility of taking the ball
lightning for usual lightning was practically excluded.
At a distance up to 100 m the electric circuit was destroyed. In
spite of the large
amount of water on the soil and the strong rain the soil was
charred and melted in
a region of 1.5 m diameter and 200-250 mm depth. The whole volume
of the region
filled with slag was ca. 0.4 m\3. The slag consisted not only of
the crust, but of many
pieces of irregular form with average size 50-60 mm mutually
bound together. The
total number of these pieces was over 1000. Near the place where
the flash was
observed the surface vegetation did not appear again.
http://abob.libs.uga.edu/bobk/ccc/cc040401.html
(9) EM EFFECTS CAUSED BY IMPACTS OF LARGE METEOROIDS
Ivan V. Nemtchinov <ivvan@idg1.chph.ras.ru>
http://abob.libs.uga.edu/bobk/ccc/cc050300.html
2) EXPERTS DEMAND BETTER ASTEROID ALERT
>From Space.com, 2 May 2000
http://www.space.com/scienceastronomy/astronomy/classified_impacts_000502.html
On January 18, over a remote area of northwest Canada, a
meteorite
exploded, releasing the equivalent blast of a 4-5 kiloton bomb.
"It was a big object. I estimate somewhere between six and
nine-feet
(2-3-meters) in diameter. We don't usually get hit that hard
except
once every 5 to 10 years," Tagliaferri said.
Defense Department satellite sensors caught the incoming object
as it
plunged toward Earth, he said.
Plowing through the atmosphere above Yukon Territory, sonic booms
startled residents as far away as British Columbia and Alaska.
When the fireball exploded at an altitude of 16 miles
(25-kilometers),
it turned darkness on the ground to daylight. So bright was the
explosion that streetlights operating on solar cells turned
themselves
off. As the meteorite extinguished itself, the lights immediately
turned back on, overloading the local power grid. That in turn
caused
electrical switching hardware to fail.
From:
http://www.airpower.maxwell.af.mil/airchronicles/cc/france2.html
As a final note in an effort to highlight the threat posed by
asteroids of all sizes, one need only look back a few
months and a bit north to the Yukon Territory of Canada. On 18
January 2000, a small meteor (estimated at several kg)
entered the Earth's atmosphere and exploded at an altitude of
about 25 km. While the explosion (equivalent to between
two and three kilotons of TNT) shook houses and was witnessed
over an area of thousands of square miles in this sparsely
populated region, the most interesting effect surprised many
observers.8 It seems that the meteor's explosion produced
an electromagnetic pulse similar to that of a low-yield nuclear
device-an effect of nuclear weapons known to have dire
consequences for electronic equipment and often predicted as a
precursor to a nuclear strike curing the Cold War.
http://www.airpower.maxwell.af.mil/airchronicles/cc/france1.gif
Figure 1 Yukon Power Grid Voltage, 18 Jan 00
Figure 1 above shows the voltage spike measured in the
(admittedly small) Yukon power grid.9 This spike, in turn, caused
a power outage over one-third of the province with power restored
some hours later. In imagining a similar incident
occurring over a major metropolitan area, the possibilities for
damage, panic and misinterpretation seem significant. A
meteor of this size may not be large enough to identify far
enough in advance to divert it (and the cost to destroy or
divert it may not justify such an operation), but its timely
detection and the subsequent warning of its expected strike
could save many lives and reduce property damage greatly. The
event also serves as another vivid reminder of the
frequency with which meteor and asteroid reentries with
measurable effects occur.
Additional observations:
http://abob.libs.uga.edu/bobk/hotwater.html
http://abob.libs.uga.edu/bobk/caseof.html
http://abob.libs.uga.edu/bobk/iceoxy.html
http://abob.libs.uga.edu/bobk/maha/mahbfr.html
http://abob.libs.uga.edu/bobk/maha/mahab077.djv
http://abob.libs.uga.edu/bobk/chant/
http://djvued.libs.uga.edu/chant/
http://djvued.libs.uga.edu/ls/
Bob Kobres
Main Library
University of Georgia
Athens, GA 30602
bkobres@arches.uga.edu
http://abob.libs.uga.edu/bobk
--------------------------------------------------------------------
CCNet is a scholarly electronic network. To
subscribe/unsubscribe, please
contact the moderator Benny J Peiser < b.j.peiser@livjm.ac.uk
>. Information
circulated on this network is for scholarly and educational use
only. The
attached information may not be copied or reproduced for
any other purposes without prior permission of the copyright
holders. The
fully indexed archive of the CCNet, from February 1997 on, can be
found at
http://abob.libs.uga.edu/bobk/cccmenu.html.
DISCLAIMER: The opinions,
beliefs and viewpoints expressed in the articles and texts and in
other
CCNet contributions do not necessarily reflect the opinions,
beliefs and
viewpoints of the moderator of this network.
*
CCNet ESSAY, 18 April 2002
--------------------------
DREADNOUGHTS, DREADNAUTS &
EXCALIBUR-II: SPECIFICATION OF CRITERIA FOR
OPTIMAL DETECTION OF MAXIMALLY HAZARDOUS NEOs
By Drake A. Mitchell, PlanetaryDefence@Netscape.Net
"The search strategy should evolve synergistically as
knowledge of
the NEO population accrues."
-- Edward Bowell, Karri Muinonen, 1994, in "Hazards Due to
Comets & Asteroids"
I: THE CURRENT STRATEGIC PARADIGM: FLAIL
Current efforts to detect potentially hazardous NEOs depend on
ground-based
optical telescopes to sample regions of space, primarily cones
extending
from the Earth towards the Main Belt. These efforts to find
asteroids and
comets in the many orbits of concern rely on the fact that these
NEOs appear
to these telescopes to be most brightly illuminated at
solar-opposition from
the Earth, i.e. in the antisolar direction of the night sky. Thus
a
searchlight-like zone slowly swings along with the Earth in its
perennial
orbit of the Sun. This data-collection strategy has yielded an
optimization
for search-cost and viable political compromise, in the form of
the goal
proposed to and then mandated by the U.S. Congress, i.e. for NASA
to detect
90% of NEOs 1 km and larger within the ten-year period ending in
2008. This
strategy, however, does not appear to be globally optimal when
time
parameters, hazard metrics, true costs, best effort, and
alternate
strategies are taken into account. We are the inheritors of bad
news: God
apparently does play dice, terribly sorry about that; but the bad
news
really must all be collected, and the sooner the better, chin up,
chop-chop!
