PLEASE NOTE:
*
CCNet 44/2003 - 1 May 2003
----------------------------------
"A major catastrophe 251 million years ago left life
teetering on the brink of oblivion. Now for the first time we
have a clear picture of what caused it, says leading
palaeontologist Michael Benton"
--New Scientist, 26 April 2003 (p.38)
"Sometimes in science, if you want answers, you just have to
bust things up. That's what Kazushige Tomeoka and colleagues did
in order to learn why most of the space dust that falls to Earth
is wet, while larger space rocks found on the planet are usually
dry as a bone."
--Robert
Roy Britt, Space.com, 30 April 2003
(1) WIPEOUT: NEXT ROUND IN THE PERMO-TRIASSIC MASS EXTINCTION
DEBATE
New Scientist, 26 April 2003 (p.38)
(2) 'SHOCKING' EXPERIMENT REVEALS HOW ASTEROIDS EXPLODE
Space.com, 30 April 2003
(3) METEORITES UNDER FIRE
Nature, 1 May 2003
(4) ASTEROIDAL LAVA FLOWS
Planetary Science Research, 28 April 2003
(5) BEPPOSAX SATELLITE FALLS HARMLESSLY INTO OCEAN
Space.com, 30 April 2003
(6) H. JAY MELOSH ELECTED TO NATIONAL ACADEMY OF SCIENCES
Ron Baalke <baalke@zagami.jpl.nasa.gov>
(7) BRAVO SLOAN AND AIAA
Andy Smith <astrosafe22000@yahoo.com>
=============
(1) WIPEOUT: NEXT ROUND IN THE PERMO-TRIASSIC MASS EXTINCTION
DEBATE
From New Scientist, 26 April 2003 (p.38)
A major catastrophe 251 million years ago left life teetering on
the brink of oblivion. Now for the first time we have a clear
picture of what caused it, says leading palaeontologist Michael
Benton
251 MILLION years ago, at the end of the Permian period, life on
Earth was almost completely wiped out by an environmental
catastrophe of a magnitude never seen before or since. All over
the world complex ecosystems were destroyed. In the sea, coral
reefs, fishes, shellfish, trilobites, plankton, and many other
groups disappeared. On land, the sabre-toothed gorgonopsian
reptiles and their rhinoceros-sized prey, the dinocephalians and
pareiasaurs, were wiped out forever. Only 5 per cent of species
survived the catastrophe, and for the next 500,000 years life
itself teetered on the brink of oblivion. What terrible event
could have wrought such havoc?
Two theories have been proposed -the impact of a huge meteorite
or comet over 10 kilometres in diameter, or a massive and
prolonged volcanic eruption. Up to now the evidence has been
equivocal. But the data has been accumulating over the past 10
years, and the picture is now clear enough to say with some
certainty what happened.
An impact might seem a tempting model. A massive catastrophe
demands an extraordinary explanation -something unexpected,
something from outer space. And we know that impacts can cause
mass extinctions. It seems that the dinosaurs and many other
groups of animals and plants were wiped out 65 million years ago
by the impact of a huge meteorite in modern day Mexico. The
crater has been found, there is good evidence for the shock wave,
and for the fa1lout rocks and dust all round the world. In
February 2001, a team of scientists claimed they had found clear
evidence that the mass extinction at the end of the Permian was
also caused by a meteorite impact. Luanne Becker of the
University of Washington in Seattle and her colleagues from NASA
and other institutions announced in a paper in Science (Vol291, p
1530 ) that they had found extraterrestrial helium and argon in
rocks from the Permo-Triassic boundary in China and Japan.
The gases were trapped inside the fullerenes or buckyballs that
are often associated with impact debris. When Becker and her team
looked closely at the helium and argon they found isotope ratios
like nothing else on Earth, but similar to those found in
meteorites. On this basis they argued that the fullerenes -and
their entrapped gases -must have come from an impact.
The claim was splashed all over the press. On 23 February 2001,
The New York Times reported "Meteor crash led to extinctions
in era before dinosaurs". The Times said, "Asteroid
collision left the world almost lifeless".
But later in 2001, several learned journals published critiques
in which other geochemists tried and failed to replicate Becker's
results. Other samples from the same boundary bed in China
apparently contained no buckyballs, argon or helium, and a
Japanese geologist, Yukio Isozaki of the University of Tokyo,
pointed out that the Japanese sample came from a rock formation
that didn't even include the Permian-Triassic boundary.
But Becker and her team still stand by their results. They
repeated their analyses from the Chinese samples, and confirmed
the helium result. They also have support from an independent
source. ln September 2001, Kunio Kaiho ofTohoku University in
Japan reported that sediment grains from Permo-Triassic boundary
sections in China show evidence of compression by impact, as well
as geochemical shifts indicative of a huge impact -though his
data is far from conclusive.
All in al1, the evidence for an impact at the Permo-Triassic
boundary is limited when compared with the mass of evidence for
an asteroid hit at the end of the Cretaceous: the iridium anomaly
(a worldwide spike in the abundance of iridium, an element
derived from meteorite impacts); shocked quartz (grains showing
evidence of high-pressure modification); glassy spherules (melt
particles derived from sedimentary rocks); and above all an
enormous crater of the correct age. The discovery of a Permian
equivalent of any of these could confirm the impact theory at any
moment. But for now, most geologists do not accept the impact
model for the crisis at the end of the Permian.
Instead, their attention has focused on Earth-bound processes.
The idea is that massive volcanic eruptions, sustained over
half-a-million years or more, caused catastrophic environmental
deterioration -poison gas, global warming, stripping of soils and
plants from the landscape,
eruption of gases from their frozen locations deep in the oceans,
and mass deoxygenation. The evidence for this version of events
is compelling compared with the impact hypothesis.
First and foremost, the end of the Permian was indeed
characterised by huge volcanic eruptions. The remains of these
are preserved in the Siberian Traps, a vast accumulation of
basalt lavas some 3 million cubic kilometres in volume and
covering 3.9 million square kilometres of what is now eastern
Russia.
Precise dating of the Siberian Traps shows that they span the
boundary between the Permian and the Triassic, with the eruptions
beginning perhaps 500,000 years before.
The Siberian Traps were not formed by explosive eruptions from
classic cone-shaped volcanoes. More commonly, basalt is erupted
through fissures, long cracks in the ground, as happens on
Iceland today. Such eruptions last for a long time, and the lava
bubbles up in huge volumes, spreading sideways from the fissure.
They are accompanied by prodigious outpourings of gases, mostly
carbon dioxide.
The effect of these gases was devastating. The full story of the
havoc they wrought is written in the sedimentary rocks that span
the Permo-Triassic boundary. Until the 1990s, geologists had to
rely on incomplete or hard-to-date sections in northern Italy,
Pakistan and Afghanistan. Reputedly excellent sections in
southern China were not available to overseas geologists, mainly
for political reasons. Nothing daunted, British geologists Tony
Hallam of the University of Birmingham and Paul Wignall of the
University of Leeds obtained a modest travel grant from the Royal
Society, and went to China in 1991. What they found amazed them :
the rock record was complete, and it told the story of the crisis
millimetre-by-millimetre as they worked their way through the
rocks from bottom to top.
Hallam and Wignall focused on sections around the Meishan
township. Working up through the succession, the last rocks
deposited in the Permian were limestones containing diverse and
abundant fossils, such as foraminiferans (microscopic shelled
protozoans), brachiopods (lamp shells), and conodonts (jaw
elements from primitive fish-likevertebrates). Rarer fossils
include cephalopods (coiled molluscs that are distant relatives
of the modern squid and octopus), sea urchins, starfish and small
crustaceans called ostracods, all typical of warm, shallow seas.
Near the top, there is extensive burrowing in the limestones,
indicating conditions of full oxygenation. Clearly, life at this
time was diverse and abundant.
Then, suddenly, everything changes. The thick, burrowed
limestones disappear, and with them the abundant fossils. The
limestone is capped by a mineral-rich layer containing lots of
pyrite -a classic marker of very low atmospheric oxygen. On top
of this are three layers of limestone, mudstone and clay,
encompassing about half a million years. These layers, numbered
as beds 25, 26 and 27 in the Chinese system, tell how the crisis
unfolded, so let's look at them in more detail. The oldest layer,
bed 25, is a thin band of pale-coloured clay 5 centimetres thick
in which fossils are very rare, just a few foraminiferans and
conodonts. Under the microscope, this clay contains small
iron-rich pellets and decayed pieces of quartz that indicate it
was formed from an acidic ''tuff'', an amalgam of volcanic
fragments and ash from an explosive volcanic eruption -presumably
the Siberian Traps. The next bed up, number 26, consists of 7
centimetres of dark, organic-rich limey mudstone in which fossils
are slightly more abundant-there are brachiopods, clams and
cephalopods. Based on the relatively diverse fossils, and on
geochemical evidence, oxygen levels during deposition of bed 26
were low but not anoxic.
Together, beds 25 and 26 form a distinctive dark-on-light marker
band that has been detected elsewhere in China, which is useful
for geologists who wish to make correlations from location to
location. This "ash band" has been detected so far in
12 provinces throughout China, covering at least a million square
kilometres. Whatever created it was extremely far-reaching.
Bed 27 indicates some degree of environmental recovery. The
17-centimetre-thick layer of limestone is full of burrows, so
bottom conditions were not especially low in oxygen. The lower
part of the bed contains occasional Permian brachiopod fossils
near the base. Near the top, the conodont Hindeodus parvus
appears for the first time: this is the globally accepted marker
for the beginning of the Triassic period. (Geological boundaries
are marked by the appearance of fossils, not their disappearance.
The major event happened at the base.of bed 25, but no
significant new species appeared until the middle of bed 27.)
What does it all mean? One of the stories the Meishan section
tells is of a dramatic extinction event. In the late l990s, Jin
Yugan and his colleagues from the Nanjing Institute of Geology
and Palaeontology, and Doug Erwin from the National Museum of
Natural History in Washington DC, undertook a huge sampling
programme. They found that at the base of bed 25, 116 marine
species suddenly disappeared, representing 94 per cent of the
total. Then, in the following 500,000 years stretching to the top
of bed 27, new species appear then disappear with alarming speed.
Overall a further 45 species dropped out, one at a time.
Clearly something terrible happened at the base of bed 25 and its
ramifications continued for half a million years. But what
exactly happened? Fortunately, the Meishan rock section, and
other sections elsewhere, contain a record of environmental
changes through the Permo- Triassic crisis, in the form of
isotopes of oxygen and carbon. Both elements have two stable,
naturally occurring isotopes whose ratios fluctuate depending on
environmental conditions. The isotope ratios are locked into the
skeletons of organisms during their lifetimes, so careful
recordings from the shells of bivalves or foraminiferans, for
example, can give a detailed picture of atmospheric and oceanic
conditions through time.
Oxygen isotopes are used as a palaeothermometer. Oxygen occurs in
two forms, oxygen-16 and oxygen-18. These are incorporated into
the calcite skeletons of marine creatures at differentrates
depending on the water temperature, more oxygen-18at low
temperatures, and more oxygen-16 at high. At the base of bed 25,
the main mass-extinction level, there was a sudden shift in the
oxygen isotope ratios indicating a worldwide rise in temperature
of 6C. This may not sound much, but it would have a profound
effect on the world's ecology. Climatologists have been getting
very excited recently about a half-a-degree rise in global
temperatures. The carbon isotopes suggest what might have caused
the temperature increase. They show a massive shift towards the
light isotope, carbon-12, exactly at the time of the big
extinction. Pulses of carbon-12 in the geological record are
usually indicative of a volcanic eruption or a large die-off
(plants, animals and bacteria concentrate carbon-12 in their
bodies and release it when they die). Both certainly happened at
the end of the Permian.
But the carbon-12 pulse is far too big to be explained by these
mechanisms alone. Calculations of global carbon budgets have
suggested that, even if every plant, animal, and microbe died and
was buried; altogether they would only account for about
one-fifth of the observed carbon shift. The Siberian Traps would
have added another fifth. Where did the remaining three-fifths
come from?
The extra carbon-12 was probably buried, frozen deep under the
oceans in the form of gas hydrates. These are extraordinary
accumulations of carbon-12-rich methane locked up in cages of ice
at very high pressure. If the atmosphere and oceans warm up
sufficiently, these gas reserves can suddenly melt and release
their contents in a catastrophic way. The explosion of gas
through the surface of the oceans has been termed a "methane
burp". A very large methane burp at the end of the Permian
could have produced enough carbon-12 to make up the deficit. The
cause of the burp was probably global warming triggered by huge
releases of CO2 from the Siberian Traps. Methane is a greenhouse
gas too, so a big burp raises global temperatures even further.
Normally, long-term global processes act to bring greenhouse gas
levels down. This kind of negative feedback keeps the Earth in
equilibrium. But what happens if the release of methane is so
huge and fast that normal feedback processes are overwhelmed?
Then you have a "runaway greenhouse". This is a
positive feedback system: excess carbon in the atmosphere causes
warming, the warming triggers the release of more methane from
gas hydrates, this in turn causes yet more warming, which leads
to the release of more methane and so on. As temperatures rise,
species start to go extinct. Plants and plankton die off and
oxygen levels plummet. This is what seems to have happened 251
million years ago. The effects were profound and long-lasting. In
the Meishan section, the Permo-Triassic boundary in bed 27 is
followed by a succession of dark limestones and shales containing
sparse fossils. This seems to represent a post-apocalyptic world;
in which CO21evels were still very high and the oceans and
atmosphere were starved of oxygen. The 6 per cent of species that
survived the initial onslaught were struggling. Normal recovery
processes had not yet kicked in. When oxygen levels fall, plants
and photosynthesising plankton in the sea normally replenish it
by absorbing excess CO2 and generating oxygen. After the crash at
the end of the Permian, perhaps oxygen levels had been driven so
low, and so much of plant life had been killed, that this was
impossible.
The surviving species were a very poor sample of what had lived
before: thin-shelled molluscs that required very little food and
swam languidly over the black, deoxygenated muds, and the
"living fossil" Lingula in its shallow burrows. Near
the end of the Permian period, each region of the world had its
own fauna and flora. Afterwards, the survivors became
cosmopolitan. It took 20 or 30 million years for coral reefs to
re-establish themselves, and for the forests to regrow. In some
settings, it took 50 million years or more for full ecosystem
complexity to recover. Geologists and palaeontologists are only
just beginning to get to grips with this most profound of crises.
Michael Benton is head of the Department of Earth Sciences at the
University of Bristol. His book on the end-Permian crisis, When
Life Nearly Died, has just been published by Thames & Hudson,
price 16.95
Copyright 2003, New Scientist
MODERATOR'S NOTE: For more background info on the P/T Controversy
go to:
http://abob.libs.uga.edu/bobk/ccc/cc030201.html
http://abob.libs.uga.edu/bobk/ccc/cc030501.html
http://abob.libs.uga.edu/bobk/ccc/cc030601.html
http://abob.libs.uga.edu/bobk/ccc/cc021403.html
============
(2) 'SHOCKING' EXPERIMENT REVEALS HOW ASTEROIDS EXPLODE
From Space.com, 30 April 2003
http://www.space.com/scienceastronomy/watery_meteorites_030430.html
By Robert Roy Britt
Sometimes in science, if you want answers, you just have to bust
things up. That's what Kazushige Tomeoka and colleagues did in
order to learn why most of the space dust that falls to Earth is
wet, while larger space rocks found on the planet are usually dry
as a bone.
More than 97 percent of all meteorites collected on Earth's
surface lack water. Meanwhile, about 30,000 tons of
interplanetary dust reaches Earth's surface every year. Almost
all of this dust contains water, resembling the paltry 2.8
percent of known, hydrated meteorites.
"Why is that?" wonders Tomeoka, of the Kobe University
in Japan. "There has been no convincing answer to this
question."
Scientists have been left to assume that wet space rocks simply
don't survive the trip through Earth's atmosphere.
Not buying that explanation, Tomeoka's team decided to figure out
what happens in space when asteroids collide. With a specially
designed gun -- 16 feet long (5 meters) with a 30 millimeter bore
-- they shot meteorites with projectiles moving at up to 4,026
mph (1.8 kilometers per second).
The result was as revealing as it was explosive.
"The application of shock to the watery meteorite reduces it
to minute particles and produces explosive expansion upon release
of the pressure," Tomeoka told SPACE.com. "In contrast,
the dry meteorite does not show significant changes."
The researchers conclude that what's collected on Earth is a
result of what happens in space. When watery asteroids are
shocked at the surface by an impact -- something that happens to
all space rocks several times during their histories -- dust
explodes into space. When a dry asteroid is hit by a another
rock, not much happens, dustwise.
"As a result of these differences in shock response, watery
material would become the predominant kind of dust particles
produced by mutual collisions of asteroids, Tomeoka said, adding
that larger watery fragments would not be abundant.
Most asteroids roam around the Sun in a belt between Mars and
Jupiter. The fragments of their collisions, and the dust, can be
drawn toward the inner solar system and sometimes approach Earth.
Dust and rocks moving fast in relation to Earth frequently slam
into the atmosphere and burn up, generating shooting stars. Stuff
moving more slowly relative to Earth can be captured by the
planet's gravity and survive the plunge.
The findings will be detailed in the May 1 issue of the journal
Nature.
Copyright 2003, Space.com
============
(3) METEORITES UNDER FIRE
From Nature, 1 May 2003
http://www.nature.com/nature/links/030501/030501-4.html
Each year about 30,000 tons of tiny interplanetary dust particles
fall to Earth. The composition of most of these micrometeorites
is similar to that of the larger hydrated, porous meteorites that
reach the Earth's surface. But these make up only 3% of the
recovered meteorite falls, the majority being anhydrous. This
size-related imbalance was thought to be due to atmospheric
filtering. Now by firing a propellant gun at samples from the
(hydrous) Murchison and (anhydrous) Allende meteorites, Tomeoka
et al. find evidence that the imbalance is established in space,
before contact with the atmosphere. Hydrous material shatters
over a much broader pressure range than anhydrous, suggesting
that collisions between asteroids produce a preponderance of
hydrated material in the interplanetary dust.
Interplanetary dust from the explosive dispersal of hydrated
asteroids by impacts
KAZUSHIGE TOMEOKA, KOJI KIRIYAMA, KEIKO NAKAMURA, YASUHIRO
YAMAHANA & TOSHIMORI SEKINE
Nature 423, 60-62 (2003); doi:10.1038/nature01567
© 2003 Nature Publishing Group
=============
(4) ASTEROIDAL LAVA FLOWS
From Planetary Science Research, 28 April 2003
http://www.psrd.hawaii.edu/April03/asteroidalLava.html
--- Meteorite studies indicate that we have pieces of lava flows
from at least five asteroids.
Written by G. Jeffrey Taylor
Hawai'i Institute of Geophysics and Planetology
Some meteorites are pieces of lava flows. They have the expected
minerals present and the crystals are intertwined in a
characteristic way indicative of crystallization in a lava flow.
This shows that lavas erupted on at least some asteroids. Age
dating indicates that the eruptions took place 4.5 billion years
ago. Planetary scientists have recognized three main groups of
asteroidal lava flows, each distinctive enough to show that they
must come from different asteroids. The most abundant are the
eucrites, which might actually hail from asteroid 4 Vesta.
Mesosiderites are complex mixtures of smashed up volcanic rock
and metallic iron. Angrites have a distinctive group of minerals
in them, but also clearly formed by volcanism. Recent studies
increase the number of groups to five.
David Mittlefehldt (Johnson Space Center) and colleagues Marvin
Killgore (Southwest Meteorite Lab) and Michael Lee (Hernandez
Engineering, Houston, Texas) show that the five known angrites
probably represent at least two different asteroids. Four of the
angrites are fairly similar to each other in chemical
composition, but a fourth, Angra dos Reis, was very different and
may come from an entirely different asteroid. (This is ironic as
the group derives its name from Angra dos Reis.) Akira Yamaguchi
(National Institute of Polar Research, Tokyo, Japan) and
colleagues in Japan at the University of Chicago show that a
recently found eucrite, Northwest Africa 011 (NWA 011 for short),
has a quite different composition of its oxygen isotopes than the
rest of the eucrites. They suggest that NWA 011 comes from a
different asteroid than the other eucrites. Thus, it appears that
we have samples of lava flows from five different asteroids.
References:
Yamaguchi, A., Clayton, R. N., Mayeda, T. K., Ebihara, M., Oura,
Y., Miura, Y., Haramura, H., Misawa, K., Kojima, H., and Nagao,
K. (2002) A new source of basaltic meteorites inferred from
Northwest Africa 011. Science, vol. 296, p. 334-336.
Mittlefehldt, D. W., Killgore, M., and Lee, M. T. (2002)
Petrology and geochemistry of D'Orbigny, geochemistry of Sahara
99555, and the origin of angrites. Meteoritics and Planetary
Science, vol. 32, p. 345-369.
--------------------------------------------------------------------------------
Lava Flows and Eruptions on Asteroids
Even big asteroids have fairly puny gravitational fields. This
means that we have to modify how we think magma is transported
inside these little planets and how lava is erupted. This is not
a one-way street, however. Making the adjustments sharpens our
understanding of how magma transport and eruptions happen on
larger planets. These comparisons are one of the great benefits
of planetary science to understanding the Earth.
FULL ARTICLE at http://www.psrd.hawaii.edu/April03/asteroidalLava.html
===========
(5) BEPPOSAX SATELLITE FALLS HARMLESSLY INTO OCEAN
From Space.com, 30 April 2003
http://www.space.com/missionlaunches/bepposax_falls_030430.html
By Andrew Bridges
AP Science Writer
LOS ANGELES (AP) _ Everything that goes up must come down,
including a 3,086-pound Dutch-Italian satellite that splashed
into the Pacific Ocean seven years after being sent into space.
The BeppoSAX satellite re-entered the Earth's atmosphere around
5:57 p.m. EDT Tuesday, mission member Giovanni Mussoni said by
phone from Rome.
It fell in the equatorial Pacific with the debris closest to land
splashing down about 186 miles northwest of the Galapagos
Islands.
``The important thing is it fell in the Pacific,'' Mussoni said.
The Agenzia Spaziale Italiana initially put 39 countries on
notice that portions of BeppoSAX could come down on their
territory.
But the odds were always greatest that the fragments would splash
harmlessly into the ocean, said William Ailor, director of The
Aerospace Corp.'s Center for Orbital and Reentry Debris Studies
in El Segundo.
The Italian space agency estimated that as much as 1,325 pounds
of the satellite would survive the fiery passage through the
atmosphere and rain down on Earth. Those fragments were expected
to include chunks of stainless steel and titanium weighing as
much as 220 pounds.
BeppoSAX's end came nearly seven years to the day after its April
30, 1996, launch. The Earth-orbiting, X-ray observatory is best
known for its discovery of 50 gamma-ray bursts, explosions more
powerful than anything known since the Big Bang.
The satellite was switched off April 30, 2002.
As many as 100 basketball-size and larger human-made objects fall
to Earth each year. Only one person is known to have ever been
struck by orbital debris -- an Oklahoma woman who was not
injured, Ailor said.
Copyright 2003, Space.com
============
(6) H. JAY MELOSH ELECTED TO NATIONAL ACADEMY OF SCIENCES
From Ron Baalke < baalke@zagami.jpl.nasa.gov >
From Lori Stiles, UA News Services, 520-621-1877
April 30, 2003
University of Arizona Professor H. Jay Melosh of the Lunar and
Planetary Laboratory (LPL) has been elected to the National
Academy of Sciences, one of the most prestigious honors in
American science.
The Academy, chartered in 1863 by President Abraham Lincoln to
guide public action in science, yesterday elected 72 new members
and 18 foreign associates from 11 countries in recognition of
their distinguished and continuing achievements in original
research.
"Jay Melosh literally wrote the book on impact
cratering," said Michael Drake, head of the LPL and UA
planetary sciences department. "His 1989 book made us all
aware of the importance of extraterrestrial impacts in shaping
our Earth. The book ("Impact Cratering: A Geologic
Process," Oxford University Press) is still the universal
reference used by all scholars."
-----------------------------------
Contact Information
H. Jay Melosh
520-621-2896 jmelosh@lpl.arizona.edu
Michael Drake
520-621-6962 drake@lpl.arizona.edu
------------------------------------
Melosh said he learned of his election at 8 a.m. yesterday, when
he logged on his computer to check for an important e-mail
message.
He said he didn't expect this one, from UA Regents' Professor and
NAS member J. Randy Jokipii, informing him of his election to the
Academy.
About an hour later, Melosh said, Jokipii reached him by phone
from a cab near a Washington, D.C., airport.
"Randy says he tried to get me out of bed with news at 7
a.m. (he would not have!), but had to settle for e-mail because
my home number in the LPL phone listings is incorrect."
"I've been getting lots of phone calls, lots of e-mails. It
is really amazing," Melosh said. "I'm somewhat
surprised. I figure I'd never be elected because the science I do
is sometimes controversial. It tends to rock the boat."
Melosh said he is reluctant to compare or rank the honors he has
been given, but admits that "this one is certainly way up
there."
"Jay's work has helped us understand the origin of the Moon
in a giant impact of a Mars-sized object with the growing Earth.
Jay figured out how we get meteorites from the Moon and Mars,
helping us understand that we had 'free' space missions courtesy
of mother nature," Drake said.
"He has shown how impacts into the ocean cannot cause havoc
the way depicted in movies like Deep Impact - hint: giant waves
break way out to sea and dissipate their destructive energy by
the time they reach shore.
"He has shown how the dinosaurs and most species on Earth
perished 65 million years ago when a large impact into what is
now Mexico ejected material up through the atmosphere. This
material reentered the atmosphere like ballistic missiles,
heating the atmosphere to hotter than a conventional oven can
achieve, thereby burning plants, animals, and trees
globally," Drake said.
"Jay has shown how enormous landslides travel tens of miles
down very shallow slopes. I could go on, but his contributions to
knowledge are extraordinary.
"Add to this scholarship the fact that he is an
extraordinary teacher, and he represents everything the State of
Arizona would want in a faculty member.
"He is also precisely the type of faculty member who could
be recruited by another university because of the short-sighted
budgetary recommendations of the legislature these past few
years," Drake said. "The erosion of the university's
budget must be reversed if we are to retain scholars of the
caliber of Jay Melosh."
Melosh graduated magna cum laude with a bachelor of arts degree
in physics from Princeton University in 1969, and earned his
doctorate in physics and geology from Caltech in 1973. He joined
the UA faculty in 1982, where he has supervised 12 doctoral
students in planetary sciences.
Melosh is author or co-author of more than 150 scientific papers
and has served on numerous national and international committees
and panels that guide scientific planning, publications,
facilities, and awards in his discipline. His numerous awards and
fellowships most recently include the Barringer Medal of the
Meteoritical Society (1999), Asteroid 8216 "Melosh"
approved by the International Astronomical Union (2000), the
Gilbert Medal of the Geological Society of America (2001), and
Fellow of the American Association for the Advancement of Science
(2001).
Melosh is on the 12-member science team for Deep Impact, a $279
million robotic mission that will become the first to penetrate
the surface of a comet when it smashes its camera-carrying copper
probe into Comet Tempel 1 on July 4, 2005.
============================
* LETTERS TO THE MODERATOR *
============================
(7) BRAVO SLOAN AND AIAA
From Andy Smith < astrosafe22000@yahoo.com >
Hello Benny and CCNet,
The large survey telescopes (LST) can make a very important
contribution to the search for the dangerous near-earth objects
(NEO) that threaten us...especially those smaller than magnitude
20. We were therefore delighted to see the recent announcement of
the 2nd Release of the Sloan (SDSS) Digital Sky Moving Object
Catalog. We salute Zeljko Ivezic and all who contributed to this
outstanding work (134,335 observations, 26,847 orbital elements).
We also encourage the other LST teams, around the world, to join
in helping to meet this vital challenge.
Planetary Defense Conference
We also want to thank the American Institute of Aeronautics and
Astronautics (AIAA) and the Aerospace Corporation for sponsoring
the upcoming Planetary Defense Conference (California, next
February). This landmark conference will focus on asteroid/comet
impact prevention, civil emergency preparedness, etc. and we
encourage the global technical community to make submissions and
to participate. Abstracts must be sent before July 2003. It would
be especially beneficial, to the global effort, to hear of new
activities by Spaceshield Foundation institutions and
specialists.
The conference organizers have devoted a major effort to
organizing and defining the conference sessions and we will be
happy to assist any CCNet participants who wish to attend. It may
be possible to obtain limited translation services, if they are
needed. We have been very impressed with the planning team and
are looking forward to an outstanding conference. We also hope
they will make the abstracts and papers available on the Web...to
join the excellent files from the 1995 Planetary Defense
Workshop, the Spaceshield PDE Conferences and other outstanding
technical meetings on this vital subject.
Earth & Space 2004
We are also assisting the Amercian Society of Civil Engineers
(ASCE) to organize Earth & Space 2004, in Houston, Texas,
next March. This conference will emphasize structural
issues and robotics and we are hoping to continue and to
advance the dialogue on tsunami-resistant structures and on
planetary defense, in the Houston community.
These conferences provide an excellent opportunity to inform the
policy makers, the technical media and many other important
groups of the issues and needs related to planetary
protection...and we value them highly.
4th Generation Asteroid Telescopes
Plans for the very promising next generation of asteroid
telescopes are moving forward, at an
encouraging pace, and we invite the CCNet community to examine
the additions to the web pages for the POI (Air Force, U. Hawaii
et al) and the LSST (Dark-Matter Telescope). These programs
should open the door to the identification of that large
population of smaller...but extremely dangerous...NEO. They
feature a new generation of CCD cameras and could make it
possible to complete the critical inventory in a decade (instead
of more than a century)....working in cooperation with our
excellent family of active NEO search teams.
Cheers
Andy Smith/IPPA astrosafe22000@yahoo.com
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