PLEASE NOTE:
*
Date sent: Thu, 29 May 1997 08:33:38 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: Possible Meteorite Fall in Australia
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
from: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>:
National Science Foundation
NSF PR 97-41 May 28, 1997
Contact:
Cheryl Dybas
(703) 306-1070/cdybas@nsf.gov
Program contact:
Dan Weill
(703) 306-1558/dweill@nsf.gov
SEISMIC MYSTERY REMAINS IN AUSTRALIA
SCIENTIST-SLEUTHS TO REPORT ON LATEST FINDINGS
It's a tale of Down Under, set against a backdrop of
international
terrorism.
On a dark night in May, 1993, somewhere in the empty miles of
dry-as-dust Australian outback, a streak blazed through the sky
and
the ground shook, according to eyewitnesses, aborigines
prospecting
for gold.
In a likely script for an episode of the "X Files," the
event
happened near a ranch owned by the Japanese cult "Aum
Shinrikyo,"
the group accused of the poison-gas attack on Tokyo subways in
1995. Investigators in Australia and the United States raised
concerns, at first, that the seismicity might be the result of
cult
activities. Cult followers had recently acquired land on the
outback, and were known to be mining uranium and carrying out
weapons tests there.
The U.S. Senate's Permanent Subcommittee on Investigations became
interested and requested that scientists affiliated with the
National Science Foundation (NSF)-supported Incorporated Research
Institutions for Seismology (IRIS) in Washington, D.C., look into
the incident. IRIS scientists have been studying, ever since,
seismic recordings of the occurrence for the subcommittee.
The sleuths have concluded from seismic data -- after ruling out
a
nuclear detonation -- that the earth's trembling on that dark May
night could have been caused by the impact of a meteorite made of
iron.
The scientists will present a report on their latest findings,
Earthquake Sources: Processes and New Observations, at the spring
meeting of the American Geophysical Union, May 28, at 1:30 p.m.
at
the Baltimore Convention Center.
"If the eyewitness accounts are credible," says
seismologist
Gregory van der Vink, director of planning at IRIS, "the
seismic
signal was most likely created by the impact of an iron meteorite
about two meters in diameter. Such a meteorite could survive
passage through the atmosphere, and impact earth with sufficient
energy to create the seismic signal picked up by one of our
stations in the Global Seismographic Network." But, as there
is no
previously known digital seismic signal from a meteorite impact,
"we have nothing to compare this record to," adds
Christel Hennet,
van der Vink's colleague at IRIS.
The IRIS scientists -- joined in their quest by researchers Danny
Harvey of the University of Colorado, Chris Chyba of the
University
of Arizona, and Vipin Gupta of Sandia National Laboratory --
estimate that only about once every ten years does an iron
meteorite of this size survive its hurtling free-fall through
earth's atmosphere, and reach our planet's surface intact.
"A meteorite this size would create a crater and thus
provide
positive evidence of what the seismic network readings
indicate,"
says van der Vink. "But as yet, no such crater has been
found."
The impact of a meteorite this large would produce a hole the
size
of a football field, difficult to overlook in populous regions of
the world, but perhaps hard to find in the wide Australian
outback,
the equivalent of trying to locate a contact lens in a barn.
"But
we now have a good determination of the location from analyzing
the
seismic records, and are working with Sandia Labs to track it
down," says van der Vink. "We're closing in on an
answer to this
mystery."
If no crater can be found, says van der Vink, then the event may
have been caused by an earthquake.
If a crater is never found, and there is no credible alternative
explanation for the eyewitness accounts, he says, "we may
never
know what happened that night in a remote corner of
Australia."
-NSF-
*
Date sent: Thu, 29 May 1997 08:30:39 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: COSMIC RAIN & ICE
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
from: Duncan Steel <dis@a011.aone.net.au>:
Douglas Isbell
Headquarters, Washington, DC May 28, 1997
(Phone: 202/358-1753)
William A. Steigerwald
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/286-8955)
RELEASE: 97-112
POLAR SPACECRAFT IMAGES SUPPORT THEORY OF INTERPLANETARY
SNOWBALLS SPRAYING EARTH'S UPPER ATMOSPHERE
Images from NASA's Polar spacecraft provide new evidence
that Earth's upper atmosphere is being sprayed by a steady
stream of water-bearing objects comparable to small comets.
Using Polar's Visible Imaging System (VIS), a research
team led by Dr. Louis A. Frank of the University of Iowa in
Iowa City has detected objects that streak toward Earth,
disintegrate at high altitudes and deposit large clouds of
water vapor in the upper atmosphere. Frank's research is being
reported in a news briefing at 10 a.m. today at the spring
meeting of the American Geophysical Union at the Convention
Center in Baltimore, MD.
The incoming objects, which Frank estimates to be the size
of a small house, pose no threat to people on Earth, nor to
astronauts in orbit. "They break up and are destroyed at 600
to
15,000 miles above the Earth," Frank noted. "In fact,
this
relatively gentle 'cosmic rain' -- which possibly contains
simple organic compounds -- may well have nurtured the
development of life on our planet."
"This is an intriguing result that requires further
scientific investigation," said Dr. George Withbroe, science
director for the Sun-Earth Connection program in NASA's Office of
Space Science. "We need to look closely at measurements from
other
sensors to find out if they see related signatures in the
atmosphere, now that we have learned more about what to look
for."
The Polar cameras have imaged trails of light in both
ultraviolet and visible wavelengths as the objects disintegrate
above the atmosphere. Using a filter that detects visible
light emitted only by fragments of water molecules, Frank has
shown that the objects consist primarily of water.
"The Polar results definitely demonstrate that there are
objects entering the Earth's upper atmosphere that contain a
lot of water," commented Dr. Thomas M. Donahue, a noted
atmospheric physicist and professor at the University of
Michigan in Ann Arbor.
"The images show that we have a large population of
objects in the Earth's vicinity that have not been detected
before," said Frank, who designed the VIS instrument.
"We
detect these objects at a rate that suggest Earth is being
bombarded by five to 30 small comets per minute, or thousands
per day." Comets are known to contain frozen water and are
sometimes called "dirty snowballs".
Frank's new observations are consistent with a
controversial theory he proposed in 1986 to explain the
existence of dark spots, which he termed "atmospheric
holes",
in images of the sunlit atmosphere of the Earth. He first
detected these holes while analyzing data from an ultraviolet
imager flown on NASA's Dynamics Explorer 1 spacecraft. He
theorized that the holes were caused by the disintegration of
small icy comets in the upper atmosphere. The water vapor they
produce momentarily absorbs the ultraviolet solar radiation
scattered from oxygen atoms in the upper atmosphere, preventing
it from reaching his camera and resulting in a dark spot on the
image. These holes have diameters of 15 to 25 miles.
His theory of a new class of objects in the Solar System
ignited a wide-ranging controversy. Many colleagues discounted
the appearance of the holes as an instrumental problem. But
the new images from Polar also include observations of
atmospheric holes in much greater detail than before,
suggesting that they are real. "These results certainly
vindicate Lou Frank's earlier observations", said Donahue.
"These remarkable images cap a great first year for
Polar," added Dr. Robert Hoffman, Project Scientist for
Polar,
which is operated and managed by NASA's Goddard Space Flight
Center, Greenbelt, MD. "I am pleased that Polar's
instruments
were able to actually detect these objects streaking towards
the Earth and disintegrating into clouds of water vapor. They
give scientists a fascinating new and important phenomenon to
take into account in theories of Solar System evolution."
Images of the comets and the atmospheric holes can be
found on the World Wide Web at the following URL:
http://pao.gsfc.nasa.gov/gsfc/newsroom/flash/flash.htm
*
Date sent: Thu, 29 May 1997 08:27:37 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: COMET CRASH
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
from: Duncan Steel <dis@a011.aone.net.au>:
Comet Crash: Teraflops Computer Simulates Colossal Comet Impact
Into Ocean
Sandia exercise a tuneup for world's fastest computer
By Ken Frazier
Sandia Lab News Editor
ALBUQUERQUE, N.M. -- Even before it's at full strength, the new
teraflops (trillion operations per second) supercomputer at
Sandia
National Laboratories is making a big splash worldwide.
During the initial testing of the new computer, Gil Weigand, U.S.
Department of Energy (DOE) Deputy Assistant Secretary for
Strategic Computing and Simulation, requested that Sandia
complete
a simulation that would be of general interest to the scientific
community. For this reason, and also to generate unclassified
data
to test innovative visualization techniques, Sandia scientist
David Crawford has carried out a computational simulation of a
major cosmic event of potential significance to all people on
Earth: What would happen if a kilometer-wide comet struck the
ocean?
A kilometer is about the size of the largest fragment of Comet
Shoemaker-Levy 9 that crashed into Jupiter in 1994 -- an event
that was also the subject of highly praised computational
simulations by Crawford and colleague Mark Boslough. The close
correspondence between those predictions of a visible plume
rising
above the rim of Jupiter and the actual plume as observed by
astronomers lent even more confidence to the accuracy of the
Sandia simulation codes.
The new calculation again used Sandia's CTH "bang and
splat" shock
physics code, but this time the simulation was run on 1,500
processors of the new Intel Teraflops computer being installed at
the Labs. That's only one-sixth of the expected final
9,000-processor configuration.
The calculation assumed a 1-kilometer-diameter comet (weighing
about a billion tons) traveling 60 kilometers per second and
impacting Earth's atmosphere at about a 45 angle. This is small
as far as comets go (the massive Comet Hale-Bopp weighs about ten
trillion tons).
The problem was divided into 54 million zones and ran for 48
hours.
The results, although dramatic, pretty much confirm earlier
predictions about a comet impact, but they do so with much finer
resolution in three dimensions than has ever before been
possible.
A revolution in science
"What's unique about this is we can now do three-dimensional
simulations on the Intel teraflops computer that can fully
resolve
all the physics of the impact," Crawford says.
The fully-resolved three-dimensional resolution is extraordinary.
"It's like an astronomer getting a new, more powerful
telescope,"
says Boslough. "I think it's a major step forward in
science." He
said the capability raises computational simulations to the
status
of a third branch of scientific inquiry equal to, and
complementary
to, experimentation and theorizing.
"It really is a revolution in science," Crawford says.
"A lot of
major breakthroughs in science are going to come from these kinds
of supercomputers." He notes that the comet-impact
simulation is
something that can't be done any other way. "It's almost
like
doing an experiment -- one you could never do. One you would
never
want to do."
300-gigaton impact
Here's what the new Sandia simulations show.
The simulation starts with the comet 30 kilometers above the
surface. The comet produces a strong luminescent bow shock in the
atmosphere as it speeds downwards. Seven-tenths of a second later
it hits the ocean with an impact energy of 300 gigatons of TNT --
about 10 times the explosive power of all the nuclear weapons in
existence in the 1960s at the height of the Cold War -- forming a
large transient cavity in the ocean and a dent in the ocean
floor.
The comet itself is almost instantaneously vaporized, along with
300 to 500 cubic kilometers of ocean. This high-pressure steam
explosion rises into the atmosphere. Comet vapor and water vapor
are ejected into ballistic trajectories that will take it around
the globe, with some of it even achieving escape velocity.
Low-lying areas like Florida would indeed be washed over, but
Crawford says the event is very close to the size threshold at
which impact experts expect that a global catastrophe could
occur,
by screening out much sunlight for long periods of time and
disrupting agriculture, among other effects. "Simulations of
this
kind can help pin down that energy threshold and help answer the
question: Is it a regional or global catastrophe?"
Low-probability, high consequence
What is the likelihood of something like this happening?
Boslough says the estimated probability is that an asteroid or
comet with this energy strikes Earth about once every 300,000
years. Another way of looking at it is that there is about a 1 in
3,000 chance of its happening in a given century. "It's a
low-probability, high-consequence event," he says. "But
if it did
hit, the probability of your becoming a victim would be
high."
Sandia's teraflops computer is a joint development of DOE,
Sandia,
and Intel. It represents the initial goal of DOE's Accelerated
Strategic Computing Initiative (ASCI), a ten-year program
designed
to move nuclear weapons design and maintenance from a test-based
to simulation-based approach. DOE announced last December, when
the machine was then still at Intel, that the
one-trillion-operations-per-second breakthrough had been
achieved.
The full machine is expected to have a peak performance
capability
of 1.8 teraflops, or 1.8 trillion mathematical operations per
second. DOE and the weapons labs are developing continually more
powerful supercomputers to simulate the complex 3-D physics
involved in nuclear-weapon performance and to accurately predict
the degradation of nuclear weapon components as they age in the
stockpile.
The comet-simulation was essentially a test of the teraflops
machine's capabilities. "This is an exercise for the
computer,"
says Boslough (who notes that he's also using it for a
weapon-component simulation), "but we wanted to do something
that
people would be interested in."
Sandia is a multiprogram DOE laboratory, operated by a subsidiary
of Lockheed Martin Corp. With main facilities in Albuquerque,
N.M., and Livermore, Calif., Sandia has major research and
development responsibilities in national security, energy, and
environmental technologies and economic competitiveness.
--30--
Color images and animation are available at this Web site:
http://www.sandia.gov/1431/COMETw.html
*
Date sent: Thu, 29 May 1997 08:23:16 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: Rutgers Geologists Find Evidence in New Jersey of a
Massive Meteorite
Strike
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
from: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>:
Rutger University
May 27, 1997
FOR IMMEDIATE RELEASE
TO THE POINT: Rutgers geologists find "one of the final
pieces in
the puzzle of what happened to the dinosaurs"
NEW BRUNSWICK/PISCATAWAY, N.J. -- Rutgers geologists are the
first
to find evidence in New Jersey that a meteorite strike in Mexico
millions of years ago formed a massive cloud of vaporized rock
and
other materials that caused widespread extinctions of plankton,
and
is almost certainly the same event that caused the extinction of
the dinosaurs.
"The cloud of materials was so fast-moving and huge that it
got
from Mexico to New Jersey in about 10 minutes and fell to earth
forming a layer of glass beads known as spherules that is more
than
2 inches thick," said Kenneth G. Miller, professor and vice
chairman of geological sciences at Rutgers.
The event resulted in the extinction of more than 90 percent of
the
plankton found in earlier deposits, he said, unequivocally
linking
the Mexican meteorite impact to the mass extinctions at the end
of
the Mesozoic period.
He described the findings as "one of the final pieces in the
puzzle
of what happened to the dinosaurs."
"Although the 'kill mechanism' for the extinction of the
dinosaurs
isn't definite," he said, "most scientists favor a
scenario in
which dust from the impact shut down photosynthesis for a short
period, resulting in the collapse of the dinosaurs' food
chain."
Miller and Richard K. Olsson, a professor of geological sciences
at
Rutgers, presented their findings Wednesday (May 28) at the
spring
meeting of the American Geophysical Union (AGU) in Baltimore. The
AGU is the premier organization of geophysicists and geologists
in
the United States. The paper has been accepted for publication in
the journal Geology published by the Geological Society of
America.
Miller teaches undergraduate and graduate courses in marine
geology
and stratigraphy. Olsson teaches undergraduate and graduate
courses
in micropaleontology and earth history. Both are members of the
Faculty of Arts and Sciences at Rutgers in New Brunswick.
Miller and Peter Sugarman of the New Jersey Geological Survey
(NJGS) are co-chief scientists for the New Jersey Coastal Plain
Drilling Project, a Rutgers-led effort to study global sea-level
changes over the past 65 million years. The project is part of
the
international Ocean Drilling Program, which is funded in part by
the National Science Foundation (NSF).
The project drilled a borehole nearly 2,000 feet deep in Bass
River
State Park, 13 miles north of Atlantic City, in November 1996,
Miller explained.
"Examination of the core from this borehole showed a layer
of
ballistic ejecta at the 1,260-foot level, immediately above the
Cretaceous-Tertiary boundary, which marks the end of Mesozoic
time," he said. "The layer is composed of spherules,
which are
glass droplets formed from vaporized rock, and condensate matter
that fell to earth from a cloud of materials formed by
the meteorite's impact at Chicxulub, Mexico, 65 million years
ago.
"The spherule layer settled on a muddy sea bottom making
impressions of the glass droplets. The impressions indicate that
deposition of the layer was geologically instantaneous. The
discovery of this material so far from the crater confirms that
devastating environmental effects resulted from a single impact
that occurred precisely at Cretaceous-Tertiary boundary
time."
Cooperating in the project are scientists from the Lamont-Doherty
Earth Observatory of Columbia University, Queens College, and the
City University of New York. The effort is funded by NSF, the
NJGS
and the U.S. Geological Survey.
NOTE: Miller and Olsson will return to New Jersey and be
available
for interviews Thursday (May 29). Kenneth Miller can be reached
by
calling (908) 445-3622 (office) or (908) 249-1366 (home). Richard
Olsson can be reached by calling (908) 445-3043 (office).
*
Date sent: Thu, 29 May 1997 08:20:37 -0400 (EDT)
From: Benny J Peiser <B.J.PEISER@livjm.ac.uk>
Subject: NEAR Flyby of Asteroid 253 Mathilde on June 27
To: cambridge-conference@livjm.ac.uk
Priority: NORMAL
from: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov> wrote:
From the NEAR home page: http://hurlbut.jhuapl.edu/NEAR/
NEAR EARTH ASTEROID RENDEZVOUS (NEAR)
Mathilde Encounter: June 27, 1997
The NEAR flyby of Mainbelt Asteroid 253 Mathilde:
Science Objectives and Encounter Strategy
------------------------------------------------------------------
A. Harch, J. Veverka, J.F. Bell, C. Chapman, M. Malin, L.A.
McFadden, S. Murchie, M. Robinson, P.C. Thomas, D.K.
Yeomans, B.G. Williams, S. Squyres, R.W. Farquhar, A.
Cheng, D.W. Dunham
On June 27, 1997 the NEAR spacecraft will pass within about 1200
km of main belt asteroid 253 Mathilde. Complementing the Galileo
flyby's of S-asteroids Gaspra and Ida, this will be the first
ever
close observation of a C-asteroid. Mathilde has attracted recent
attention due to its extremely slow rotation period of 17.5 days.
Primary science objectives during this 10 km/sec flyby include
high- resolution imaging, as well as albedo and spectral mapping
of the illuminated surface of the large (50x50x70 km) asteroid.
The best monochrome images will achieve resolutions of 200
meters/pixel. Global imaging in seven colors between 0.4 and 1.1
micron will be carried out at resolutions of 400-500 m/pixel. On
departure a satellite search will be made in which bodies as
small
as 100 meters across could be detected. A determination of the
mass of Mathilde to about 110% will be carried out by the Radio
Science experiment.
Due to the encounter geometry (approach phase angle 1390,
departure at 390) the best imaging of Mathilde will occur around
and just after closest approach. Locating Mathilde with
sufficient
accuracy to insure the the highest resolution observations are
obtained near closest approach requires optical navigation
updates
of Mathilde's position as late as 12 hours before encounter. This
will be the first ever fast flyby of an asteroid with a
spacecraft, which unlike Galileo, does not have a scan platform.