PLEASE NOTE:
*
CCNet 80/2003 - 30 September 2003
U.S. URGED TO MOVE SPACE PROGRAMME TOWARDS EXPLOITATION OF
ASTEROIDS
--------------------------------------------------------------------
Congressional committees are expected to hold hearings in the
fall, after the
release Aug. 26 of the report by an independent board
investigating the Columbia
spacecraft disaster, and former astronaut Rusty Schweickart has
some ideas for
those committees. The next step in space, he says, should
establish the infrastructure
to move the human environment beyond low Earth orbit. The way to
do that, he says,
is to focus on asteroids - to shift the NASA space program away
from the moon and
Mars and instead use asteroids as a cheaper resource and supply
line for moving
people into a new stage of existence beyond Earth.
--Lucy Komisar, The American Reporter,
29 September 2003
(1) GEOLOGICAL TEAM FINDS PARTS OF METEORITE
(2) 'METEORITE' PROBABLY JUST SPACE JUNK; ASTRONOMER
(3) METEORITE RIPS THROUGH HOME IN NEW ORLEANS
(4) IN THE SWEDISH ARCTIC, RESEARCHERS DIG UP THE COUNTRY'S
BIGGEST METEORITE
(5) U.S. URGED TO MOVE SPACE PROGRAMME TOWARDS EXPLOITATION OF
ASTEROIDS
(6) RE: METEORITE SHOWER DAZZLES INDIANS
(7) MARTIAN METEORITES AND THE NEW CRATER COUNTS: DO
"SECONDARY IMPACTS" OCCUR AT ALL?
(8) AND FINALLY: TED TURNER TURNS TO LIBERAL DOOMSDAY CRAZE
===========
(1) GEOLOGICAL TEAM FINDS PARTS OF METEORITE
Newindpress, 30 Sept. 2003
http://www.newindpress.com/Newsitems.asp?ID=IEQ20030929145648&Page=Q&Title=ORISSA&rLink=0
BHUBANESWAR: A two-member team from the Geological Survey of
India (GSI) has located what could be called `parts' of the
meteor in Kaptipada block of Mayurbhanj.
The remnants, according to Director, GSI B.K. Mohanty, resemble
slags and are dark in colour. However, these fragments are small
in size and also light in weight.
He said these parts of the meteor were retrieved from around the
gutted hut in Kaptipada. These fragments were probably
responsible for the fire in the thatched house, he said.
However, there could still be a bigger remnant of the meteor from
which the smaller ones emanated, Mohanty said adding, the team
was looking for it. The main portion could be lying buried
somewhere. Since a meteor travels at a tremendous speed after
entering the Earth's atmosphere, any bigger remnant would pierce
into the latter's surface.
However, the team has now been instructed to visit Balasore and
Bhadrak to find if any remnant has landed there. The team would
return to Bhubaneswar on Tuesday with the fragments.
On Monday, a second GSI team was sent to Mahakalpara block under
Kendrapara district where a 6 kg stone-like object was found by
villagers in Suniti.
===============
(2) 'METEORITE' PROBABLY JUST SPACE JUNK; ASTRONOMER
ABC News, 28 Sept. 2003
http://www.abc.net.au/news/newsitems/s955125.htm
An astronomer believes some of the 15,000 pieces of space junk
orbiting the earth were seen disintegrating over south-east
Queensland overnight.
A Gold Coast resident reported seeing what looked like a
meteorite followed by a tail of stars.
But the director of Nanango's Stuart Range Observatory, Jim
Barclay, says he believes it was a satellite burning up about
80-90 kilometres above earth.
He says all space junk will eventually disintegrate.
"A satellite is no bigger than a very small sedan motor car
or even half the size of a small hatchback, so by the time it
burns up, at around 3,000 to 10,000 degrees Celcius, it falls to
earth in microscopic dust."
===========
(3) METEORITE RIPS THROUGH HOME IN NEW ORLEANS
The Advocate, 29 Sept. 2003
http://www.2theadvocate.com/stories/092903/new_moteor001.shtml
By The Associated Press
NEW ORLEANS -- When Roy Fausset walked into his Uptown home after
work last week, he knew immediately that something was very, very
wrong.
"The powder room door was open and it looked like an
artillery shell had hit the room," he said.
Last Tuesday, something had fallen with enough force to punch a
hole through the roof and two floors before coming to rest in the
crawl space beneath the house.
It was a sandy-colored rock that appeared to have been burned
around its edges. Preliminary tests by scientists at Tulane
University indicate the rock came from outer space.
If so, that makes it an exceedingly rare phenomenon. Meteorites
enter the Earth's gravitational field with some frequency; all
but a tiny percent of them burn up during their passage through
the atmosphere _ what are commonly called shooting stars.
"We found olivine, pyroxene, plagioclase and troilite,"
a combination of minerals often found in meteorites, said Stephen
Nelson, chairman of Tulane's earth and environmental sciences
department.
Nelson used X-ray diffraction to double-check the type of
minerals that make up the rock. He had first identified the rock
as rhyolite, a form of volcanic rock found in Mexico and south
Texas.
The minerals Nelson found do not automatically mean it's a
meteorite, he said, because they're also found in the Earth's
mantle, deep underneath the planet's crust.
"But we don't commonly see pieces of mantle falling out of
the sky," he said. "And the black crust, which I
thought was a weathering line at first, perhaps it's a fusion
crust _ material that melted as it passed through the
atmosphere."
Nelson said the rock is known as a "stony meteorite," a
type more common than the black, ironlike rocks that have become
the archetypal meteorites in the public imagination.
Fausset said neighbors told him they heard what sounded like a
car crash just after 4 p.m., but they didn't know it was his home
being hit.
"One of my neighbors on South Tonti Street had two children
in her back yard, eating Popsicles, and they heard a terrific
noise," he said. "And a lady next door to her heard it.
She was indoors and ran out into her back yard, but didn't see
anything."
Finding the damage inside his home came as a shock, he said:
"We had just renovated the powder room and now there was
plaster everywhere. I looked up at the ceiling and saw this big
hole."
A quick check in the adjoining utility room revealed another hole
in the ceiling and what looked like a broken ceiling joist.
"I went outside and looked up and about midway down the
front of the roof, there was a hole about the size of a
basketball," he said.
Fausset immediately called his insurance agent, who suggested he
check upstairs to look for any more damage.
In his daughter's second-floor room, Fausset discovered that
something had smashed through the ceiling there, too, and it had
demolished an antique wicker desk before cutting a neat hole in
the wall-to-wall carpet and the flooring beneath it.
Back in the first-floor bathroom, Fausset found another hole
leading through the floor to the crawl space.
"That's when I called the police," he said. When
officers arrived, they found several chunks of rock beneath the
hole in the bottom floor that matched fragments found in
Fausset's daughter's room.
"I'm in shock," Fausset said after learning the rock
had been identified as a meteorite. "Oh, that's scary. I
will certainly go to church this Sunday, because the Lord was
certainly sending me a message."
And the meteorite?
"I guess I'll go put it in my safe-deposit box, or just
frame it," he said.
Copyright 2003, AP
==========
(4) IN THE SWEDISH ARCTIC, RESEARCHERS DIG UP THE COUNTRY'S
BIGGEST METEORITE
Associated Press, 30 Sept. 2003
STOCKHOLM, Sweden (AP) _ Swedish researchers said Tuesday that
they've dug up the biggest meteorite ever found in the country.
It took two days to unearth the 158-kilogram (348-pound)
meteorite, one of only nine found in the Scandinavian country of
9 million in the last 100 years.
The meteorite, made up mostly of nickel and ferrous iron, was
found nearly 140 kilometers (87 miles) north of the Arctic Circle
near the town of Kitkiojarvi, in early September.
It's now in the Swedish Museum of Natural History in the capital,
Stockholm, where tests are being conducted on it, museum
spokesman Jan-Olof Nystroem told The Associated Press.
The largest meteorite ever found is at the Hoba farm near
Grootfontein, Namibia. It weighs more than 50 metric tons (55
tons) and has a volume of 9 cubic meters (317 cubic feet). It hit
the ground about 80,000 years ago and was discovered in 1920.
Copyright 2003, Associated Press
=============
(5) U.S. URGED TO MOVE SPACE PROGRAMME TOWARDS EXPLOITATION OF
ASTEROIDS
The American Reporter, 29 September 2003
http://www.american-reporter.com/2,191W/72.html
by Lucy Komisar
American Reporter Correspondent
New York, N.Y.
LaBAULE, France - Congressional committees are expected to hold
hearings in the fall, after the release Aug. 26 of the report by
an independent board investigating the Columbia spacecraft
disaster, and former astronaut Rusty Schweickart has some ideas
for those committees, he told a French forum last March.
"This pause in the manned space program [after the Columbia
crash] would appear to be an excellent opportunity to rethink
things about 'why are we doing this, what are we doing, should we
keep doing it, what should we do instead?'" he said.
The next step in space, he says, should establish the
infrastructure to move the human environment beyond low Earth
orbit.
The way to do that, he says, is to focus on asteroids - to shift
the NASA space program away from the moon and Mars and instead
use asteroids as a cheaper resource and supply line for moving
people into a new stage of existence beyond Earth.
Schweickart spoke recently at the annual meeting of Forum 21 (http://www.forum-21.com/), a
gathering in France of Americans and Europeans who meet to
discuss key issues in science, politics and culture. The
conference was started in 2001 by Paul Weinstein and Abby Hirsch
Weinstein, Americans living in Paris. He is president of Rive
Droite International Investments and she is a journalist. The
Forum met this spring in LaBaule, on the Atlantic coast of
Brittany
Schweickart was the lunar module pilot for the Apollo 9 space
flight, March 3-13, 1969, logging 241 hours in space. It was the
third manned flight of the Apollo series and the first manned
flight of the lunar module. During a 46 minute space walk,
Schweickart tested the portable life support backpack which would
be used on the lunar surface explorations.
He was backup commander for the first Skylab mission of spring
1973. Following the loss of the thermal shield during launch, he
took charge of development of hardware and procedures to erect an
emergency solar shade and deploy the jammed solar array wing,
which transformed Skylab from a near disaster to a successful
operation. He received the NASA Exceptional Service Medal for the
Skylab rescue.
At Forum 21, Schweickart laid out the reasons for moving the
human environment further into space.
"The human environment, which has been relegated to the
surface of the Earth, a bit on the surface of the waters and a
little in the air, has within the last 30 or 40 years extended
into near Earth space, into what is called low Earth orbit. I'll
extend that definition out to the geostationary orbit where all
the communication satellites are."
Near-Earth space, said Schweickart, is now "essential human
territory - it affects your pocketbook and mine, your cell phone
and mine, it is part of the everyday environment; economic,
financial, technical, engineering, business, jobs," he said.
But he wants to move beyond near-Earth to the exploration of
asteroids.
"We're talking about working with NASA to have "beyond
low Earth orbit for human flight. That means let's head to the
asteroids instead of their current idea of let's go back to the
moon or lets go to Mars. This is what I call the Goldilocks
principle. Going back to the moon is 'been there, done that;'
it's too small a bed. Going to Mars is too big a step. What's
just right is going to an asteroid. This is a nice comfortable
intermediate destination. It takes less energy, therefore less
money to go to an asteroid, if you pick the right one, than to go
back to the moon. So let's do that."
There have been several suggestions written to NASA, the
Congress, and the Administration by Schweickart and others. He
has gotten no response and knows of no others.
There is also a theoretical purpose. He said, "Asteroids are
a heck of a lot more interesting than the moon. They have a lot
to do with the origin of life. We don't quite know where life
came from or how it evolved, but we do know that asteroids had a
lot to do with it. We also came out of this process, so we want
to understand asteroids - how were they made, where did they come
from, do they have life embedded in them? They certainly have the
components of life."
Secondly, they are resources, said Schweickart. He said a major
expense of operating in space is moving supplies and equipment up
from Earth. He said asteroids could be used to develop supplies
(especially fuel) and even support life.
He gives a crucial reason for facilitating space exploration of
the kind that could extend the human environment beyond the
confines of the Earth. He declared, "Survival of this life
experiment will ultimately depend on us being able to diversify
life to other places, not just on this single vulnerable planet.
So there is a functional evolutionary reason for
exploration."
The reason he says is the threat from asteroids that could crash
into Earth. He explains that asteroids have not just shaped life
once it emerged, but periodically wiped it out." He said,
"I call it the cosmic gardener. The tree of life grows on
Earth, and from time to time this crazy cosmic gardener comes in
and cuts off the tree of life - whack, in crazy slashes. Then it
grows up again in many new diverse forms. Then whack comes
another slice from the cosmic gardener." This has happened
many times in the evolution of life here on Earth.
"We're now on the top of the food chain. The dinosaurs used
to be. We don't want to be like them. They got taken out of the
food chain by the impact of an asteroid about 65 million years
ago. That's very recent in time, not like back at the beginning
of the world. If the Earth were formed January 1 a year ago and
now its December 31, midnight, the dinosaurs got wiped out late
on December 27, just a couple of days ago," he said.
"You can have quite a few social and political catastrophes
without eliminating humanity, but one of these guys will
eliminate everybody at the same time. Each of you has about the
same probably of dying as result of asteroid strike as in an
airline accident. However, unlike the airline accident, everyone
goes at once!" he joked.
"I'm interested in seeing that we have enough time to
diversify humankind throughout the universe by protecting the
Earth so we have a chance to do that. The requirements for
ultimate survival of life as we know it is protection from these
things that occasionally hit us to enable us to have the time to
go out there and roam around, live out there - at least for
vacations," he quipped.
That issue of extending the realm of humans in space is being
taken up in NASA where, he said, "There are people talking
about beyond low Earth orbit as a concept, as an organizing
principle. The idea is we should be extending our thinking about
the human sphere of activity beyond low Earth orbit. Not just an
occasional spacecraft being shot out there, but having an
operational environment which exists beyond low Earth
orbit."
He said this would require new technology, "because it costs
much too much if you're going to rely on chemical energy to try
to set up operations at those distances." Those new
technologies will be ion propulsion or plasma propulsion, which
are extremely efficient propulsion systems. He explained,
"It's as if you took your 20 mile per gallon car and didn't
go from 20 mpg to 27 or 30 but to 200 or 300 mpg. So you're
talking about a major improvement in efficiency." These
engines will be powered by massive amounts of electricity, which
could be done efficiently only with small nuclear reactors.
"The technologies will enable us and our grandchildren and
generations beyond to begin moving out from Earth in a cost
effective way," he said.
And those powerful engines make possible another idea Schweickart
has: to push away an asteroid headed for Earth. He is chairman of
the B612 Foundation, whose purpose is to significantly alter the
orbit of an asteroid in a controlled matter by 2015. B612 is
named after the asteroid of Le Petit Prince - the little prince -
in the story of that name created by French novelist Antoine de
St. Exupéry.
"We don't want to simply sit back and wait for an asteroid
to hit us," Schweickart said. "We want to demonstrate
before one hits us, that we have the capability to move it in a
controlled way so it not only doesn't hit us, but that it doesn't
come back to hit our grandchildren." He said the plan was to
pick an asteroid, "one that's not anywhere near going to hit
us, so in case we push it the wrong way, we're not going to end
up in trouble."
The asteroid would be about 200 meters in dimension. It would be
moved by a plasma engine associated with a nuclear reactor - both
about the size of a small dining table. He said, "Go out the
street and look back to this hotel. The asteroid we're talking
about pushing is about twice the size of the hotel, and it's
spinning slowly so that every 6 hours it turns and faces the
ocean. That's what we're going to push with this spacecraft as a
demonstration that humanity has the capacity to insure its own
future from this particular cosmic threat."
"We are talking about the birth of life into the larger
universe out of the womb of Earth. This evolutionary process of
human kind is married to a technology which enables this moving
out, protecting "Mom" at the same time as we move out
and grow up into the larger universe."
Is NASA likely to follow such suggestions? Schweickart said,
"A lot of people have been justifiably critical of the space
program, that it's lost its vision. We've been flying the space
shuttle and going up and making the space station, but nobody
quite knows why we're making the space station."
But he was pessimistic a change in direction will happen. "I
suspect the main business is going to be to get back to flying,
to get back to the International Space Station," which is
being constructed largely with parts delivered by the space
shuttles.
"But one would hope if there is some rethinking going
on..."
Lucy Komisar welcomes your comments. Please send them to mailto:lkomisar@echonyc.com.
Copyright 2003 Joe Shea The American Reporter. All Rights
Reserved.
========== LETTERS =========
(6) RE: METEORITE SHOWER DAZZLES INDIANS
Vikrant Narang <vnarang@vsnl.net>
Dear Benny,
It is a great coincidence that this meteorite fall happened just
about
day after a group of villagers near Maham, Haryana in Northern
India
narrated to me and some friends (while we were there to observe
an
occultation by Ceres on the night of 25-26 September 2003), an
incident
of meteorite fall which they witnessed in 1989 and luckily
escaped. They
told us that they heard very loud noise coming from the sky while
they
were working in their fields, then some rocks fell from above and
got
buried as much as about 1 foot into the ground, some rocks even
fell
close to them. These rocks had burnt appearance and were not very
heavy.
They did collect some of the rocks but they never informed anyone
as
they thought they might have come from some high altitude plane
disintegration and would be unimportant. They said that since it
happened long time back (about 14 years), now it would not be
possible
to trace the pieced they had collected.
Our team thought about scanning the nearby area in the morning,
when we
finish observing, to see if we can still find some meteorites. We
hoped
that they would be readily distinguishable. Unfortunately the sky
got
clouded at 02:00 AM local time, just about 25 minutes before the
occultation and we lost all motivation to stay back, so we
decided to
abort and return to New Delhi, which we did! :)
Thanks and Regards,
Vikrant Narang
New Delhi, India
Member, Amateur Astronomers Association of Delhi
============
(7) MARTIAN METEORITES AND THE NEW CRATER COUNTS: DO
"SECONDARY IMPACTS" OCCUR AT ALL?
E.P. Grondine <epgrondine@hotmail.com>
Hello Benny -
As the new crater counts on the planets of our solar system are
proceeding,
the resulting high crater counts appear to be causing
consternation among
some researchers. The recent CC note on two new papers on
"secondary
impacts" (SURPRISING IMPACTS ON MARS AND EUROPA, New studies
show secondary
cratering may be of primary importance, Richard Talcott,
Astronomy.com, 12
Sept. 2003,
http://www.astronomy.com/Content/Dynamic/Articles/000/000/001/483lymqh.asp,
http://abob.libs.uga.edu/bobk/ccc/cc091603.html)
rather immediately brought
to my mind some of the earlier discussions on impact mechanisms
on the
meteorite list, as the question "Do "secondary
impacts" occur at all?" was
examined there to a fair degree.
I guess that most Conference participants have some familiarity
with the
martian meteorites, those chunks of Mars which were launched from
that
planet's surface by massive impacts millions and millions of
years ago, and
then fortuitously made their way to our own planet, the
Earth. Minimally, I
am quite confident that everyone here has at least heard of ALH
84001, that
chunk of Mars in which Dr. McKay found structures which may be
the fossils
of some primitive Mars life forms -
These meteorites as a class have usually been definitively
identified as
being from Mars due to their possession of certain radioactive
isotopes in
certain ratios which occur only on Mars, and nowhere else in our
solar
system. The times of these meteorites ejections from Mars
have been
determined by other techniques of nuclear chemistry, as have
their transit
times, and the times of their arrivals on our planet, Earth.
Finally, the mechanics of these rocks ejection from Mars has been
examined
in detail, and this brings me to the point at hand: in the case
of impacts
at cosmic velocities, apparently there may be very few
"secondary impacts",
if there are any at all.
To begin, Bernd Pauli passed along this recent (1999) overview on
impact
mechanics by McSween:
"The kinetic energy requirements for liberating fragments
from asteroids are
really quite modest. In fact, some future astronaut standing on
the surface
of a small asteroid could possibly launch a rock to escape
velocity by using
no more than a baseball throw.
"Large bodies, however, are a different story. Although
large moons and
planets experience the same buffeting by impacts that asteroids
do, their
massive gravity fields exert a near stranglehold on the fragments
produced
during cratering. It was once supposed that any smaller chips
that might be
ejected from planets by impacts would have experienced such high
degrees of
shock that they would be pulverized, melted, or even vaporized.
Yet no other
natural means of meteorite ejection seems possible. The energy of
rapidly
expanding gases during volcanic eruptions is far too small to
accelerate
fragments to planetary escape velocities, and other geologic
phenomena are
even less capable launching mechanisms.
"How, then, have we received intact pieces of the Moon and
probably Mars?
The answer, at least in part, is provided by calculations in
which
differences in the impact behaviors of target materials near the
ground
surface versus those at depth are considered. The disturbance
created by an
impacting object propagates through the subsurface as a stress
wave whose
force lessens as it moves away from the impact site, like an
expanding wave
produced when a pebble is thrown into a pond. Target rocks close
to the
impact site are melted and broken into dust or small grains, with
the
fragment size increasing away from ground zero, as illustrated in
Figure
8.6. However, rocks very near the ground surface experience
several kinds of
shock waves that partially cancel each other. This area of wave
interference
offers some shelter from the full force of the shock wave.
Calculations
indicate that some of this near-surface material will spall off
as
relatively unshocked fragments that can be accelerated to high
speeds.
Limited shock is important in the case of lunar meteorites and
nakhlites,
which have experienced only minor shock metamorphism.
"The only potential problem with this explanation is that
the chips ejected
at planetary escape velocities should be rather small. The lunar
meteorites
are generally the size of golf balls, and calculations indicate
that rocks
of this size could readily escape from the Moon's gravitational
grasp
(requiring a speed of 2.4 km/s). Some Martian meteorites are
larger,
however, up to grapefruit sizes, and these are thought to have
lost perhaps
half their original mass during transit through the Earth's
atmosphere. The
largest craters in the young terrain of Mars, a necessary
location from
which to derive most of these young meteorites, are approximately
30 km in
diameter. The sizes of the fragments that could be accelerated to
Martian
escape velocity (approximately 5 km/s) from such craters are
approximately 1
m, so large craters are apparently capable of launching small
rocks from
planetary surfaces.
"The precise mechanisms by which rocks escape from planetary
gravity fields
are not well understood. Computer simulations (sometimes called
Monte Carlo
simulations, an allusion to the statistical nature of these
calculations)
allow the orbital evolution of individual particles in space to
be tracked.
Once free of the gravitational hold of the Moon, a lunar
meteorite may go
into orbit about the Earth, eventually spiraling into our planet
within a
few decades. Most lunar ejecta, however, will be propelled into
elliptical
orbits about the Sun. These objects periodically reapproach the
Earth and on
close approaches may be scattered into new orbits by the Earth's
gravitational field. Some of these Sun-orbiting bodies will fall
to Earth,
usually within a million years or so, with the remainder
eventually being
driven into the Sun or ejected from the solar system. Rocks
launched from
Mars take significantly longer to reach the Earth than do lunar
rocks,
simply because their orbits do not initially cross that of our
planet. These
objects, like those in the asteroid belt, are subject to
resonances related
to other planets and, over a few millions of years, their orbits
are
perturbed so as to become Earth crossing. Most that fall to Earth
will do so
within 10 million years or so, with much of the remainder
eventually being
driven into the Sun.
McSween H.Y., Jr. (1999) Meteorites and Their Parent Planets, 2nd
Edition,
Cambridge University Press, pp. 242-244: The Planetary Prison,
via Bernd
Pauli
In two other notes, spliced together here, Elton Jones provided
the
meteorite list with more information bearing on the mechanics of
impact at
cosmic velocities:
"Let me add one more item to the ejecta mechanism. Indulge
me, if you may,
as I develop background. I want to explain a munitions
dynamic which can be
may used to understand the ejecta dynamics of target rock and
jetting stream
at the instant after first contact.
"Placement of explosives with different shapes can be used
to focus a hot
(kelvin-hot) jetting stream or to construct a
pressure/containment vessel,
as in the Fat Man plutonium bomb. In the field of munitions, we
have what is
called a "shape charge" (aka HEAT) which, when
detonated, produces a
directed hot gas jet, contained only by the converging shock
waves as it
dissipates in one direction.
"As it jets, it carries along with it the copper liner of
the charge - only
the liner is deformed from a flat piece of metal into a hollow
tube in a
"nano-moment". What is interesting is how the tube
forms. Based on high
speed x-ray photography, we see the elongation of the wall of the
copper-tube comes from the inside out. As molten copper is
forced by hot
gas from the copper plate back at the point of detonation, it is
added to
the tip. Apparently, the velocity of the stream gets faster
inside the tube
such that the last bit of copper is added to
the front of the tube. This tube is powerful enough to
punch through armor
plate in that aforementioned "nano-moment".
"Even more interesting is the fact that the armor plate
material, which is
being hammered out of the way in this nano-moment, is ducted back
down what
we believe is a concentrically flowing, bi-directional pipeline,
as the
energy of the jet ultimately dissipates. This occurs
without pinching off
the outward bound stream. The diameters from front to back
taper very
little. The tube diameter and length are proportional to the
diameter of the
initial charge. Whether or not the target object is
encountered by the jet,
it behaves the same
over
munitions-significant distances. There
is no observable reverse flow if not fired into a solid object.
"Final point here is that for years, we believed one thing
about this
process until X-ray photography showed us something entirely
unforeseen.
"I have seen the discussion of pressure convergence behind a
impactor at the
instant after impact. It appears that there is a similar but
larger jet
which is focused by back pressures rushing around the body till
they
collide. At this point they jet out and back in a stream of
material from
the country rock and impactor in what I have seen called "an
atmospheric
blow-out event"...
"One thing I might add to the atmospheric blowout theory,
that I know from
directed explosives and pressure distributions, is that upon
impact, the
lowest pressure region is straight up. The ground and the
atmospheric
pressure around the circumference of the impact offer higher
resistance than
does the area immediately behind the impactor. The excess
pressure follows
the path of least resistance. While much of the over
pressure radiates out
from ground zero, there is a highly directional hypervelocity
molten jet
which tends to form back through the center of the disintegrated
impactor.
(Equal and opposite reactions, etc. In this case the reactions
collide and
take an upward vector.) This should carry with it a great amount
of molten
material. The crater itself tends to focus the debris stream--not
unlike a
mortar barrel.
"Even though atmospheric pressure declines with altitude,
the jet does not
tend to expand laterally as much as one would think, likely due
to the
momentum of the jet. Once the jet material has left the
atmosphere there is
a vacuum over the site which I am inclined to believe extends
into space.
This [vacuum] does not close immediately due to the laterally
displaced
atmospheres outward momentum. This outward momentum
eventually slows and
reverses as the pressure pushes the gas and pyroclastic mixture
back towards
the evacuated hole in the atmosphere...
"What I DON'T believe by this timeline [is] that there is
any material in
the void which has any upward velocity component to push anything
else into
space. Whatever droplets remain should shower in the
vicinity/region of the
impact site influenced by whatever wind dispersions as there may
be. This
would be the micro tektite distribution, I think. What I DO
believe is that
the jet can explain how the tektite source can achieve orbit or
sub orbit.
"Earth" meteorites might be able to achieve orbit from
the rebound, but I
can't visualize how they could do so intact and unshocked if they
rose
within or near the jet...
"Therefore, I am wondering if the dynamics of focused
explosives--its
curious bi-directional and simultaneous gas stream, and the
highly
directional pressures-- could account for the containment of the
ejected
material (vaporized or not) up the column. Could it do so
long enough for
there to be a coalescence in the absence of the atmospherical
cooling
requirements for tektite formation? I would find it remote
that much of the
material would retain strata from before the impact, but I could
theorize
the deposition of successive coatings accumulating on the tube
surface
before it exceeded its elasticity and separated into successive
globs of
glass.
"The math is beyond me but is it plausible, based upon what
we believe
happens, if the jet behaves like munitions jets do? If so,
does this reduce
the dependence of atmosphere in tektite formation? Does tektite
formation
fall back to sufficient escape velocity, suitable target rock,
and
sufficient sized impactors to allow a grand scale formation of a
jetting
structure?"
EL Jones
As a final relevant item, Dave Freeman passed along the following
pratical
insights into "secondary" cratering:
From: David Freeman
"Hi Kelly, Bob, Vern, and Ernie;
"I spent eight years working in a very large open pit coal
mine and half of
that time was spent drilling and blasting rock. The
cretaceous overburden
and inter burden had varying densities and toughness, and the
powder factors
used to fracture the rock types did vary considerably. The
cap rock layer
just above the coal was the finer silts tone of the formation and
was the
hardest to fracture for digging...which is the main point of the
whole
exercise.
"My connection to the thread is how many tons of fly rock I
witnessed first
hand. Fly rock is wasted energy, as no fracturing of the
formation takes
place if the energy is expelled upward with a handful of free
flying rocks
instead of coupling to the formation and fracturing rock, and
thus allowing
for ease of excavation. It made great entertainment though, and
great
experience for ejecta theories of mine.
"A rock that is sitting on the surface and lifted with
energy will rise and
not really fracture much on its way up to say a couple thousand
feet
elevation, boom and up she goes. (Even stemming a blast hole with
rocks will
simulate a cannon going off.) Rock that is still attached
firmly to terra
firma will fracture and have much internal structural damage.
"What really fractures rock is when it stops real
fast.....imagine a 50
pound rock of hardness 6 mohs that is dropped down a few thousand
feet
through thin air (6,500 feet) and hits a hard packed road bed and
stops in
about 5 milliseconds. That is what really breaks the rock.
Rock will
survive the blast up, but will loose cohesion upon impact.
Indirectly, did
the rock get pre-stressed when it was "ejected"?
"Another one for simulation, place a 30 pound rock, hardness
6 mohs, on top
of a partial roll of 50 grain blasting cord and touch it off.
With the loose
coupling of the rock just sitting on the cardboard roll, the rock
goes up
and a large air blast is produced, and the rock is a little worn
for the
ride up, [but] the stop at the bottom seems more detrimental to
the rock. A
similar rock placed directly on a single line of blasting cord,
where the
rock is directly touching the cord when detonated, will result in
the rock
having a inch deep cut in the rock, if it was not lifted skyward
to fly
(rock was heavier than the ability of the cords energy to over
come the
gravity and establish lift), and just picked up a little.
"It was evident to me that the coupling factor, cushioning
of initial
acceleration, seemed to be a very determining factor in the
survival of the
ejecta...[as was] if it fell on the haul road, on a truck, or in
a field
when it returned to earth.
"Blasting cord detonation is 30,000 feet per second (?), and
the ammonium
nitrate velocity of detonation is 25,000 feet per second (or
approximately,
my memory fails me in some numbers). In fracturing the rock, one
needed to
blast to a free face in order to allow the energy to work the
rock to a
place where it could become free to expand and fracture. A
few times when
starting a new pit, we made some blind blasts to start a free
face. Fly
rock was three to five times greater in height and angles of exit
when there
was no readily available path to free movement. We would be
about a mile
back from blind face shots. I ran out the lead in line,
played on the pit
radio, and initiated the blasts...with adult supervision of
course. I have
a few pictures around if anyone would like to see fly rock for a
little
visual candy of energy releasing against gravity.
"I hope this was food for thought. If you are still
here, the interesting
thing is that the shock wave going out doesn't break the rock as
much
effectively as the returning shock wave reversing back in toward
the zone of
detonation.
"Have a blast, more fun than matches!"
Dave Freeman
In other words, any "secondary impactors" are traveling
at relatively slow
speeds, and they rise and then simply fracture upon returning to
a planet's
surface, producing little cratering: if they have survived the
blast, they
are traveling too slow to produce impact craters of much size.
Given the constraints of physics discussed above, do
"secondary impacts"
occur at all? Well, one way of checking this hypothesis is
to examine the
areas around large impact craters here on Earth. For
example, exactly how
many "secondary impacts" are there at Barringer Crater,
Arizona? I've never
seen any mentioned. And exactly how many "secondary
impacts" were produced
by Chixulub?
MARTIAN METEORITES AND THE NEW CRATER COUNTS:
DATING THE LARGE MARS CRATERS
One of the problems in determining impactor flux over time (the
rate of
planetary accretion) lies with the "time" element of
the problem, in other
words determining the time when a particular impact took place.
This is
particularly true for estimating the flux of smaller impactors,
where the
"time" element is usually estimated by doing small
crater counts within
larger craters.
By extension in the opposite direction along the same scale,
another method
exists for determining the flux of small impactors, and that is
to look at
the accumulation of the very smallest impactors within a small
crater.
While nearly everyone is familiar with the meteorites which have
fallen here
on our planet, Earth, very few have given any consideration of
those very
smallest impactors which fall on our near neighboring planet,
Mars.
Fortunately, some people have:
"Meteorite accumulations on Mars, P.A. Bland*) &
T.B. Smith, ICARUS, 2000,
Vol.144, No.1, pp.21-26 *) Natural History Museum, Dept Mineral,
Cromwell
Rd, London SW7, 5BD, England
"We have modeled single-body meteoroid atmospheric entry
speeds at Mars and
the effect of drag and ablation, and identify a narrow range of
small masses
(10-50 g) that should impact Mars at survivable speeds. [Since
Mars lacks
much of an atmosphere, Bland and Smith inferred that larger
meteorites would
hit its surface at nearly their initial cosmic velocities, and
thus simply
pulverize into dust, an inference which may or may not be true,
depending on
angle of entry - epg]
"The rate of oxidative weathering is much lower than that on
Earth, so this
small flux of meteorites could give rise to significant
accumulations: ca. 5
x 10(2) to 5 x 10(5) meteorites greater than 10 g in mass per
square
kilometer. [The abstract fails to mention Bland and Smith's time
scale here
- epg]
"Given that extremely large numbers of meteorites may be
present on Mars,
future sample-return missions should consider the real
possibility that they
may recover meteoritic material. Due to the low weathering rate,
meteorites
may survive on the surface of Mars for more than 10(9) years
[That is
1,000,000,000 years, in other words one billion years - epg],
preserving a
record of the temporal variability of the meteoroid flux and the
compositional evolution of the meteoroid complex. Intact
carbonaceous
chondrites may also preserve organic compounds from degradation
by
ultraviolet radiation. Terrestrial meteorites may be present, but
would
probably be sterile. (C) 2000 Academic Press."
(via Elton Jones)
How does Bland and Smith's hypothesized model of martian
meteorites hold up?
Fortunately, we have 3 sample images of the surface of
Mars to examine in
detail:
http://mars.sgi.com/MPF/ops/pan_enhanced.gif
from Pathfinder;
http://www.donaldedavis.com/BIGPUB/V2WIDERP.JPG
from Viking 2;
http://antwrp.gsfc.nasa.gov/apod/image/0107/mars_surface_vik1_big.jpg
http://mars-news.de/color/12B069.jpg
from Viking 1.
While the colors in all of these images are well known not to be
true, for
the purposes at hand this fact can be ignored for the moment.
What do we see in these image samples? First off, we see
the everpresent
red dust, which most likely is the product of the hypervelocity
impacts of
iron asteroids and meteorites with Mars (see discussion by EL
Jones above).
Beneath this red dust, in the rare spots where the dust has been
removed
either by the Martian wind or by mechanical excavation, we see a
gray
subsoil which appears similar to that which has been seen on our
Moon. In
regards to this "soil", it is also not commonly
understood that every year
our planet Earth picks up several tons of meteoritic dust.
Nonetheless, a
fine science project for young people is to have them use a
magnet to
recover some of this dust from the rain gutters of houses where
it
accumulates, and to then examine it under a microscope.
As Mars must perforce receive the same meteoritic dust as the
Earth does, it
thus appears from these images that this meteoritic dust is not
mixed by
water with the red iron dust, as it would be on Earth, but
instead the red
dust remains separate. Instead, it may be that there is just
sufficient
water on Mars to allow this meteoritic dust to form a kind of
concrete which
lies just below that planet's iron dust covering.
Having examined these omnipresent features, finally we see a
large number of
pock marked rocks. While it has commonly been assumed that
these pock marks
are the result either of these rocks being struck by grains
thrown off from
nearby large impacts, or by the process of these rocks themselves
being
ejected from an impact crater, one must now ask whether this is
always the
case. Here on the Earth, meteorites show pock marks which were
produced by
their being struck by other meteorites while they were still in
the asteroid
belt, and these features survive their entry through our
atmosphere.
So how many of these "martian" rocks are native, and
how many of them are
meteorites? Take a careful look at the images. Note
carefully Bland and
Smith's estimated martian meteorite surface survival time: 1
Billion years.
That a rock has not been rounded, as meteorites are by smaller
impacts while
they are still in the asteroid belt, is no guarantee that it is
native to
Mars: it may have been fractured by later large impacts after its
arrival on
Mars.
Further, trying to determine which rocks are native to Mars and
which are
meteorites by examining their spectra is futile at this point.
While it is
true that martian meteorites will initially have an ablative
coating after
their entry through Mars atmosphere, these ablative coatings will
have long
since been removed over the millions of years by the abrasive
action of the
dust carried by the Martian wind. No, at least one barrier to
answering this
question is that the images of Mars' surface have never been
color corrected
to their true values, or for that matter in some cases had their
details
enhanced via the computer addition of separate images. While
doing so would
involve the allocation of several million dollars to JPL's
Imaging
Laboratory, one must remember that these images were recovered by
the
expenditure of several billions of dollars, sums roughly a
thousand times
greater than this amount.
At this point, I now put forward a reason for this failure to
carefully
examine the images of Mars which were obtained at such great
cost: my
conjecture is that the reason that these color corrections have
never been
funded, or the images of Mars surface examined in detail for
meteorites, is
that it is simply too agreeable to the human mind to desire Mars
to resemble
the desert south west of the United States: many people would
rather have an
easily habitable Earth-like planet near-by, rather than a cold
dead
radioactive lump. In other words, a large number of people,
including
significantly most of the politically active "space
enthusiasts",
desperately want a "new frontier", rather than no place
to begin anew. One
must ask if there is any other social mechanism which can explain
how while
these fundamental facts of the physics of planetary accretion
were
acknowledged for years, they were never pursued...
As a final conclusion, it would thus seem that in this area, as
is true in
so many areas of impact research, the barrier to an understanding
of the
processes involved may lie in the nature of the human mind
itself. Very few
particularly care for the results of impact research, and many
are simply
emotionally unable to face up to the hazard.
Well, Benny, that's it for now. As always, I remain, yours
in science,
Ed
===========
(8) AND FINALLY: TED TURNER TURNS TO LIBERAL DOOMSDAY CRAZE
The Atlanta Journal Constitution, 29 Sept. 2003
http://www.ajc.com/news/content/news/0903/29turner.html;COXnetJSessionID=15QtDrj1XW2lfhkAOldFZNVJSUwErnJxjWHn9wHUIUy7MYcg6glS!146917677?urac=n&urvf=10649151810600.05331485814888681
Even while his three foundations continue to spend millions of
dollars on environmental and health initiatives, Ted Turner told
a newspaper group Sunday night he does not have an optimistic
outlook for the future of the world.
"If I had to predict, the way things are going, I'd say the
chances are about 50-50 that humanity will be extinct or nearly
extinct within 50 years," Turner said. "Weapons of mass
destruction, disease, I mean this global warming is scaring the
living daylights out of me."
Returning to the city that was home to the CNN and Turner
Broadcasting companies he founded, Turner was the featured
speaker at the Associated Press Managing Editors international
coverage seminar. Turner spoke to editors from 10 regional states
and admitted he may not be very good at making predictions.
"I said 20 years ago newspapers wouldn't be around in 10
years, and I was wrong," Turner said.
Turner, who now lives in Lamont, Fla., stepped down as vice
chairman of AOL Time Warner and sold 50 million shares of the
company's stock earlier this year.
"It's really a good thing those no-good weasels ran me off,
they pushed me out," Turner said, adding he now has more
time for his philanthropic projects.
Turner said his Turner Foundation focuses on environmental issues
in America. He said his U.N. Foundation already has contributed
about $600 million to support United Nations programs and will
contribute another $400 million in the next eight years to
complete his $1 billion pledge.
Turner also co-chairs the Nuclear Threat Initiative with former
U.S. Sen. Sam Nunn, an effort that allows Turner to address his
concerns that the end of the Cold War did not end the nuclear
threat.
"The most dangerous thing in the world right now is the fact
the Russian and American nuclear missiles, 10 years after the
Cold War is over, are still a hair-trigger away with less than 10
minutes response time from two presidents who thankfully are
together today," Turner said.
The ever-candid Turner also gave a negative review to the U.S.
efforts in Iraq.
"We spent $87 billion to blow Iraq up and then we spent
another $87 billion to put it back together, and all to get one
man and we still haven't got him," Turner said. "Talk
about a failure."
Turner's wealth had been estimated at more than $7 billion before
the Time Warner stock dropped sharply following its merger with
AOL. Earlier this month, Forbes Magazine estimated Turner's
wealth at $2.3 billion, good for a tie for the No. 78 position on
the magazine's list of the 400 richest Americans.
Copyright 2003, AP
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