PLEASE NOTE:


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CCNet 80/2003 - 30 September 2003
U.S. URGED TO MOVE SPACE PROGRAMME TOWARDS EXPLOITATION OF ASTEROIDS
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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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