PLEASE NOTE:
*
CCNet, 45/2000 - 6 April 2000
-----------------------------
"Nearly none of the known
near-earth objects have any chance of
hitting the earth, and there are just
two or three such objects
that researchers can't dismiss yet, said
Marsden. What happens in
most cases is that the probability of a
collision goes to zero as
more is learned about an object's orbit,
composition and other
characteristics, he said. [...] Still, a
catastrophic collision is
possible, Marsden said. A massive meteor
collision is believed to
be linked to the extinction of the
dinosaurs, he said. ‘They
weren't making observations like this so
they didn't know what hit
them.’"
--
Brian Marsden, 3 April 2000
(1) DEFENDING OUR PLANET
ABC News, 3 April 200
(2) BOULDERS ON EROS
Ron Baalke <baalke@jpl.nasa.gov>
(3) ULYSSES, COMET SPOTTER
ESA <sciweb@estec.esa.nl>
(4) ULYSSES'S SURPRISE TRIP THROUGH COMET'S TAIL PUTS HYAKUTAKE
IN RECORD BOOKS
Jacqueline Mitton <aco01@dial.pipex.com>
(5) COSMIC HERETICS GET A HEARING: DISCOVERY CHANNEL
PLANS
DOCUMENTARY ON PANSPERMIA & PERIODIC
IMPACTS
Iana Porter <Inewpony@aol.com>
(6) BALLOONING TO MARS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) ASTROBIOLOGY FIELD DRAWS RESEARCHERS
Space.com, 5 April 2000
(8) MARTIAN MAGNETIC FIELD AND ALH84001
Everett Gibson <everett.k.gibson1@jsc.nasa.gov>
(9) MARTIAN BACTERIAL MAGNETITE
Oliver Morton <abq72@pop.dial.pipex.com>
(10) METEORITE CONTAMINATION & A NULL HYPOTHESIS
Michael Paine <mpaine@tpgi.com.au>
(11) DOUBTS ABOUT VOLCANIC CATASTROPHE AD 536
Steve Zoraster <szoraster@zycor.lgc.com>
(12) SIXTH CENTURY "COMET" VECTOR
Leroy Ellenberger <c.leroy@rocketmail.com>
(13) AND FINALLY: MEDIA BOO-BOO OF THE DAY
Jeremy Tatum <UNIVERSE@uvvm.UVic.CA>
===================
(1) DEFENDING OUR PLANET
From ABC News, 3 April 200
http://abcnews.go.com/sections/science/DailyNews/arizonabservatory000403.html
Arizona Observatory Forms Main link In Earth Defense
By Jolyn Okimoto
The Associated Press
FLAGSTAFF, Ariz., April 3 - Science fiction stories are filled
with
heroes defending the Earth from collisions with asteroids and
comets.
The reality of such a campaign isn't as dramatic as movies
portray
them, but no less important to the people involved.
The Near Earth Object Search program at Lowell Observatory is one
link
in the Earth's defense chain, with its aim to identify asteroids
and comets
approaching our planet.
"We are quite concerned that one could eventually hit the
Earth," said
Lowell astronomer Edward "Ted" Bowell.
LONEOS is among five main programs dedicated to the study of
near-earth
objects, which is experiencing a golden age due to technological
advancements and growing awareness, said Brian Marsden, the
director of
the Minor Planet Center in Cambridge, Mass. The center confirms
astronomical discoveries and serves as an information
clearinghouse on
minor planets and near-earth objects.
Comet Spotting Champion
Of the five, Lincoln Near Earth Asteroid Research, or LINEAR,
located
at the Massachusetts Institute of Technology, is by far the
leader in
the field, Marsden said.
Still, Lowell's program, which operates out of Anderson Mesa
about 12
miles southeast of Flagstaff, holds its own, having discovered 29
near-earth objects in the past two years.
While the number may sound small, the following illustrates
Bowell's
view that the process is like finding a needle in a haystack:
Last
year, LONEOS recorded 276,000 observations, which resulted in 19
discoveries. A new camera installed this month could double the
number
of observations this year, program officials say.
So far, one of the most successful observers at LONEOS is Bill
Ferris,
who has discovered seven comets or asteroids since June 1998. Two
of
those comets were named for him. "He's our champion,"
Bowell said.
That's strong praise for a man whose background is in television,
not
astronomy, and coming from Bowell, who has discovered more
asteroids
than any other living astronomer.
Ferris, 38, downplays his success as a top comet finder.
"I'm no better
observer than anyone past or present," he said. "But I
certainly have
access to better technology than comet hunters of long ago."
Watching from a Windowless Room
The work of an observer isn't what one might imagine it to be.
Ferris
and other LONEOS observers sit in a windowless office - a window
would
cause light interference - analyzing computer images generated by
a
camera connected to a telescope. They look for movement, since
comets
and asteroids move while stars do not.
Observing hours are long in the winter to take advantage of
available
darkness, which in Flagstaff is nearly 11+ hours, but they shrink
down
to half that in the summer, Ferris said. "We try to observe
for every
minute," he said. Ferris said he doesn't mind the hours. He
left a
career as a TV producer and director to work in astronomy, which
he
said had always been a hobby.
"My love of astronomy led me to Lowell," he said.
Ferris said he rarely
thinks about his job as a way of defending the earth from
collisions,
but that he's glad to be part of the team keeping an eye out.
"If we
were to ever find something like that, we would like to minimize
the
loss of life and maybe prevent the event from happening," he
said.
Nearly none of the known near-earth objects have any chance of
hitting
the earth, and there are just two or three such objects that
researchers can't dismiss yet, said Marsden. What happens in most
cases
is that the probability of a collision goes to zero as more is
learned
about an object's orbit, composition and other characteristics,
he
said.
That's what happened in February when scientists determined that
an
asteroid an Italian researcher thought was on a possible
collision-course with Earth will in fact miss by millions of
miles. It
was the fifth time in two years that reports of Earth-threatening
asteroids were proven wrong.
Still, a catastrophic collision is possible, Marsden said. A
massive
meteor collision is believed to be linked to the extinction of
the
dinosaurs, he said. "They weren't making observations like
this so they
didn't know what hit them."
Copyright 2000, AP
===============
(2) BOULDERS ON EROS
From Ron Baalke <baalke@jpl.nasa.gov>
NEAR image of the day for 2000 April 4
http://near.jhuapl.edu/iod/20000404/index.html
Boulders, Boulders, Boulders
One of the most striking features in
NEAR Shoemaker images of
Eros' surface is the abundance of very large boulders. This
image of
the southwestern part of the saddle region, taken
March 6, 2000, from
a range of 201 kilometers (125 miles), shows a particularly
boulder-rich part of the surface. Many of the huge rocks are
50 meters
(164 feet) or more in diameter. They are believed to be
fragments of
Eros' native rock, shattered over the eons by
formation of impact
craters. The impacting projectiles themselves were pulverized by
the
impact process and survive only as fine debris mixed
into the
regolith.
--------------------------------------------------------
Built and managed by The Johns Hopkins University Applied Physics
Laboratory, Laurel, Maryland, NEAR-Shoemaker was the first
spacecraft
launched in NASA's Discovery Program of low-cost, small-scale
planetary
missions. See the NEAR web site for more details
(http://near.jhuapl.edu).
===============
(3) ULYSSES, COMET SPOTTER
From ESA <sciweb@estec.esa.nl>
Ulysses, the joint ESA/NASA spacecraft, has added comet spotter
to its
list of talents. Two papers published in Nature today
report that on
1 May 1996, the spacecraft flew through the tail of comet
Hyakutake whose
nucleus was more than 3.5AU (one AU equals the Sun-Earth
distance) away
at the time. "This makes it the longest comet tail ever
recorded", says
Geraint Jones from Imperial College, London who is a member of
one of the
two instrument teams that made the discovery.
Full story: http://sci.esa.int/missions/newsitem.cfm?TypeID=13&ContentID=10011
==============
(4) ULYSSES'S SURPRISE TRIP THROUGH COMET'S TAIL PUTS HYAKUTAKE
IN RECORD BOOKS
From Jacqueline Mitton <aco01@dial.pipex.com>
ROYAL ASTRONOMICAL SOCIETY
PRESS NOTICE
Ref. PN 00/06
ISSUED BY:
Dr Jacqueline Mitton
RAS Press Officer
Office & home phone: Cambridge ((0)1223) 564914
FAX: Cambridge ((0)1223) 572892
E-mail: jmitton@dial.pipex.com
RAS web: www.ras.org.uk/press/press.htm
* * * * * * * * * * * * * * * * * * * * * * * *
CONTACTS FOR THIS RELEASE
Dr. Geraint Jones
Space and Atmospheric Physics Group, The Blackett Laboratory,
Imperial College, London
Email: g.h.jones@ic.ac.uk
Telephone: +44 (0) 20 7594 7774
Fax: +44 (0) 20 7594 7772
Dr. Tim Horbury
Astronomy Unit, Queen Mary and Westfield College, London
Email: t.horbury@qmw.ac.uk
Telephone: +44 (0) 20 7775 3181
Fax: +44 (0) 20 8983 3522
Prof. Andre Balogh
Space and Atmospheric Physics Group, The Blackett Laboratory,
Imperial College, London
Email: a.balogh@ic.ac.uk
Telephone: +44 (0) 20 7594 7770
Fax: +44 (0) 20 7594 7772
WEB PAGE FOR THIS RELEASE
http://www.sp.ph.ic.ac.uk/Ulysses/comet/
(available from 19.00 BST (2.00 p.m. EDT) on April 5)
* * * * * * * * * * * * * * * * * * * * * * * *
ULYSSES'S SURPRISE TRIP THROUGH COMET'S TAIL PUTS HYAKUTAKE IN
RECORD BOOKS
Comet Hyakutake, a bright comet seen by many people in 1996,
developed the
longest comet tail ever recorded. At 570 million km (360 million
miles) it
beat the previous claimed record of 330 million km (206 million
miles) held
by the Great March Comet of 1843. The discovery was made
recently, when Dr
Geraint Jones and Professor Andre Balogh of Imperial College,
London,
together with Dr Tim Horbury of Queen Mary and Westfield College,
London
analysed 1996 data from the Ulysses spacecraft. Their analysis of
the
magnetic field data returned from Ulysses on 1 May 1996 led them
to conclude
that Ulysses had passed through a comet's tail on that date. They
then found
that the tail belonged to Comet Hyakutake. The discovery is
reported in the
journal 'Nature' on 6 April 2000.
The joint European Space Agency-NASA spacecraft Ulysses was
launched in
1990, and is in an orbit taking it over the poles of the Sun. It
makes
continuous measurements of the stream of charged particles called
the solar
wind which flows outwards from the Sun past the spacecraft. On 1
May 1996,
Ulysses was 560 million km (347 million miles) from the Sun, when
decidedly
unusual things happened to the solar wind. The first odd feature
to be
noticed was a dramatic drop in the number of protons at Ulysses,
which was
reported in 1998 by another team of scientists led by Dr Pete
Riley, then of
the Los Alamos National Laboratory. They mentioned that a comet
could
explain some aspects of the odd results.
Comet nuclei are small bodies that were formed when our solar
system was
young. They are typically a few kilometres across, and are
composed of a
mixture of ice and dust. When their orbits bring them close to
the Sun, the
rise in temperature makes them release gas and dust. The tiny
dust particles
are pushed away from the Sun by the pressure of sunlight, forming
a dust
tail. The gas particles eventually become electrically charged,
forming
ions. These ions join the solar wind flowing away from the Sun,
forming an
ion (or plasma) tail. When Jones and colleagues looked closely at
the data
returned from Ulysses's magnetometer instrument at the time, they
realised
that the solar wind's magnetic field lines displayed a
herringbone pattern -
a sign that the centre of whatever Ulysses had crossed had been
moving
slower than its edges. This is expected at comets, because the
comet's ions
slow down the solar wind when near the nucleus. This convinced
them that the
event was indeed due to a comet; so they began to search for the
comet to
which the tail belonged.
Finding the comet in question was not simply a case of looking
for known
comets between the spacecraft and the Sun on May 1 - as Ulysses
was so
distant, the solar wind flowing at 750 kilometres per second
could take days
to reach the spacecraft. This gave time for the comet to move
away from the
Sun-Ulysses line, making it trickier to find. Comet Hyakutake
(official
designation C/1996 B2) had given Earth-bound observers a
spectacular display
during late March and early April, 1996, when it approached close
to the
Earth. Discovered by Japanese amateur astronomer Yuji Hyakutake
in January
1996, the comet was at perihelion (its closest point to the Sun)
on May 1 -
the day of Ulysses's tail crossing. When Jones looked at where
Hyakutake had
been 8 days earlier, on April 23, it turned out that it had
indeed been on
the Sun-Ulysses line, and that from that point, it would take 8
days for the
ion tail to be carried to Ulysses. Using the magnetometer data,
the team
found that the tail was the right size to belong to Hyakutake,
and that it
was parallel to the comet's orbital plane, as expected. The comet
had been
identified.
Apart from the great scientific value of an encounter with a
fourth comet
(comets Giacobini-Zinner, Halley and Grigg-Skjellerup have been
visited by
other spacecraft), several aspects of the tail crossing are
particularly
intriguing. The tail's length is most surprising - Hyakutake's
tail was over
570 million km (350 million miles) long. This breaks the record
for the
longest measured tail, which is generally regarded to have been
previously
held by the Great March Comet of 1843, which had a visible tail
around 330
million km (205 million miles) long. Had Hyakutake's tail been
visible at
the time from the Earth, it would have stretched over 80 degrees
across the
sky - a very impressive length for a comet so far away. However,
at this
time, it was invisible from Earth because its head was very close
to the Sun
in the sky.
Comets' ion tails are generally thought of as pointing almost
straight away
from the Sun. The magnetometer data from Ulysses reveal that at
the
spacecraft, the tail was definitely not doing this - it was
travelling
almost sideways. Jones and colleagues explain this by the comet's
rapid
motion around perihelion. Like the jet of water from a lawn
sprinkler,
Hyakutake's tail started out pointing away from the Sun. The
further it got
from the Sun however, the more it twisted away from the
anti-sunward
direction, as a lawn sprinkler spray twists. Ion tails are
therefore curved,
especially when comets are around
perihelion. This has implications for some Earth-based comet
observations.
"A few weeks before Ulysses's tail crossing, some observers
reported tail
lengths for Hyakutake that were much longer than possible if
comet tails are
assumed to be straight, and pointing away from the Sun",
says Jones. "The
Ulysses magnetic field measurements show that these assumptions
aren't
true.", he continued, "Although it can't quite fully
account for some of the
longest tail lengths reported in late March and early April 1996,
Hyakutake's tail would have been curved in the correct way around
the Earth
for observers to see a tail longer than previously thought
possible."
When Ulysses crossed the tail, the comet's head was being
observed by the
LASCO coronagraph aboard the SOHO spacecraft, even though it
could not be
seen from Earth. "At this time," says Jones, "what
was happening at the head
of the comet didn't have any relevance to the tail at Ulysses. If
you want
to study the part of the tail crossed by Ulysses, you need to
look at images
of Hyakutake obtained around April 23. Unfortunately, few images
were
obtained then, as Hyakutake was sinking into twilight as seen
from Earth."
Nevertheless, the Ulysses results are providing unique
information on the
magnetic structures of ion tails.
The discovery, and identification of the parent comet by Jones
and
colleagues are only the beginning of the event's analysis. The
study of the
data returned from other Ulysses instruments will undoubtedly
lead to a
fuller picture of what happened when a distant spacecraft crossed
an
incredibly long tail. In the same issue of 'Nature', colleagues
of Jones and
co-workers, led by Professor George Gloeckler of the University
of Maryland,
report their independent discovery of cometary ions during the
same event
using another instrument aboard the spacecraft.
The research that led to the discovery is supported by the UK
Particle
Physics and Astronomy Research Council.
Further background information on the tail crossing, including
images and
animations, can be found from 19.00 BST (2.00 p.m. EDT) on April
5, at:
http://www.sp.ph.ic.ac.uk/Ulysses/comet/
=============
(5) COSMIC HERETICS GET A HEARING: DISCOVERY CHANNEL
PLANS
DOCUMENTARY ON PANSPERMIA & PERIODIC
IMPACTS
From Iana Porter <Inewpony@aol.com>
[as posted on the Minor Planet Mailing List]
Dear minor planet enthusiasts and professionals -
I hope it is appropriate for me to post my request on this list:
We are producing a Discovery Channel documentary special on
meteors
which is scheduled to air at the end of 2001. We are in the early
research phases and are exploring the following theories as a
possible
focus for our program: that asteroids & comets may have
originally
brought life to earth, that major extraterrestrial impacts may be
cyclical rather than random (Nemesis theory), and that our moon
may
have resulted from the impact of a mars-sized planet with earth.
We are
scheduled to begin filming in the next couple of months and
continue
over a period of about six months. I am eager to find researchers
who
are embarking on fieldwork expeditions or projects to prove or
disprove
these ideas, to investigate mysterious geology, or at least to
uncover
a piece of the puzzle ( any expeditions to impact craters, to
interesting layers in stratigraphy, meteorite fields, etc?) - or
researchers who are eloquent and outspoken about these
theories. Also,
I welcome any suggestions for other recent and intriguing
discoveries
related to asteroids, comets (meteors). Please contact me via
email at
inewpony@aol.com if you are
involved or may be able to point me in some
interesting directions! I would appreciate any suggestions you
can
offer.
Many thanks for your attention to my inquiry.
Kindest regards,
Iana Porter
Associate Producer
New Pony Productions
PO Box 989
10397 Hills Road
Mendocino, CA 95460 USA
707/937-9210 tel
707/937-9212 fax
inewpony@aol.com
========================
(6) BALLOONING TO MARS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
University Relations
University of Arkansas
CONTACT:
Larry Roe, assistant professor of mechanical engineering
(501) 575-3750, lar@engr.uark.edu
Carolyne Garcia, science and research communication officer
(501) 575-5555, cgarcia@comp.uark.edu
FOR RELEASE: APRIL 4, 2000
Ballooning To Mars
FAYETTEVILLE, Ark. -- Every day Larry Roe grapples with questions
like:
How do you inflate what does not exist, under unknown conditions,
using
unknown materials, for an unknown application? Roe, a mechanical
engineering professor at the University of Arkansas, faces these
problems in his work with NASA and the Jet Propulsion Laboratory
to
invent inflation devices for space missions.
"Some people see these questions as insurmountable
obstacles," Roe
laughs. "Those kinds of questions can drive them crazy. But
to me they
are creative challenges."
Roe's current challenge is designing systems to inflate
structures for
near-term space missions that are in various stages of planning.
For
near-term missions, Roe's designs are grounded in known
engineering
principles and existing hardware. He is looking at structures
that
range in size from a baseball to 50 meters (161 feet) across.
Subsequent missions may call for inflatables that are 3 to 5
kilometers
(2 to 3 miles) across.
For missions to Mars or other planets with sufficient atmosphere,
Roe
envisions reconnaissance balloons. These small, lightweight
devices
could collect and transmit data or carry cameras to provide
additional
views of the planet.
A number of inflatable other devices have also been identified
for
these missions, according to Roe. These structures include data
collection and communication antennas, solar shields, thermal
radiators, solar concentrators, light sails, landing systems,
rover
tires and habitats. Although vastly different in design and
purpose,
they all have a common need for some type of inflation gas.
"Currently, devices such as antennas and reflectors are
expensive,
heavy and prone to failure," noted Roe. "Inflatable
devices can
overcome these obstacles, making space explorations more reliable
and
affordable."
Inflatable structures are classified according to the type of
inflation
they require, regardless of their size. The three main categories
are
continuously inflated (CI) structures, rigidized inflatable (RI)
structures, and single-inflation (SI) devices. The gas used to
inflate
all three types must be light, non-contaminating to the
spacecraft
instruments, non-condensing under given pressure and
temperatures,
non-reactive with structural elements and able to be delivered
reliably
and controllably.
SI and RI devices are only inflated once. SI devices, such as
landing
bags are then discarded. RI structures, such as communication
antennas,
light sails or solar shields, are made of materials that can be
folded
and packaged, but harden once inflated and exposed to sunlight.
CI structures, such as data collection antennas, rover tires or
habitats present a different set of problems. They must be
continuously
inflated throughout the life of the mission, and they invariably
leak.
In addition, some CI devices can be very large. A reflecting
membrane
currently envisioned for the ARISE (Advanced Radio Interferometry
between Space and Earth) mission may be 25 meters (around 83
feet) in
diameter.
"Preliminary characterizations studies show that either a
tanked-gas or
systems that generate inflation gas via chemical reaction are
indicated," Roe explained. "Our prime candidate is the
catalytic
decomposition of hydrazine, which produces a mixture primarily of
hydrogen and nitrogen."
Roe is doing conceptual designs for projects that are about 10
years in
the future. He is focusing both on determining good ways to
inflate
devices and eliminating things that don't work. For example,
subliming
solid systems used in the Echo series of balloons have
contamination
and control issues that must be addressed before they could be
used
reliably.
Optimization is another key issue, Roe indicated. Once a viable
process
is determined, it must be made more efficient. Inflation systems
have
already been reduced in size by 50 percent, but Roe believes that
further efficiencies and size reductions are possible.
"For the near-term the primary development focus is on RI
and CI
structures," said Roe. "Inflation technology can be
incorporated into
deployable solar arrays for power, solar shields for spacecraft
thermal
management and antennas for data collection and
communication."
Roe is presenting his findings in Atlanta on April 4, 2000, at
the
American Institute of Aeronautics an Astronautics Joint
Conference on
Structures, Structural Dynamics, and Materials.
==================
(7) ASTROBIOLOGY FIELD DRAWS RESEARCHERS
From Space.com, 5 April 2000
http://www.space.com/science/searchforlife/ames_astrobiology_000405_wg.html
By Martha Mendoza
Associated Press Writer
MOFFETT FIELD, Calif. (AP) -- Two years ago, NASA took a chance
and
launched a new field of research christened
"astrobiology" with a bold
Nobel laureate at the helm and about $10 million for research.
This week, at the first ever Astrobiology Science Conference,
NASA
organizers were surprised when 600 scientists -- three times as
many as
expected -- showed up brimming with research papers, new ideas
and
enthusiasm about the questions of origins and evolution of life
in the
universe.
"This is an irresistibly exciting field," said Baruch
Blumberg,
director of the NASA Astrobiology Institute who won the 1976
Nobel
Prize for physiology and medicine. "It's like when Galileo
first looked
through a telescope and everything he saw was new."
FULL STORY at
http://www.space.com/science/searchforlife/ames_astrobiology_000405_wg.html
=============================
* LETTERS TO THE MODERATOR *
=============================
(8) MARTIAN MAGNETIC FIELD AND ALH84001
From Everett Gibson <everett.k.gibson1@jsc.nasa.gov>
The martian magnetic field died during the first 500,000 to
700,000
years (Acuna et al., 1999 SCIENCE). This was the same
period when the
martian carbonates were formed (3.94 billion years ago, Borg et.
al.,
1999, SCIENCE) in which the magnetites from the magnetotactic
bacteria
were entrapped.
Everett Gibson
=================
(9) MARTIAN BACTERIAL MAGNETITE
From Oliver Morton <abq72@pop.dial.pipex.com>
Two points on Martian bacterial magnetite. One is that early Mars
had
one hell of a magnetic field, judging by the very strong magnetic
bands
in the southern highlands seen by MGS, which are taken to be
relics of
that era. Though the field is thought to have shut down early on
(4bya
or so), the ALH84001 sample is itself from very early in Martian
history. Magnetotaxis could thus have been useful to bugs from
the
ALH84001 era.
The other is that though bacterial magnetite is used in
magnetotaxis,
it's not necessarily the case that that is all it has ever been
used
for. In fact, that seems unlikely. Remembering that a biological
innovation needs to be beneficial at each stage of its evolution,
it's hard to see how magnetosomes would evolve from scratch as
sensory
organelles, since there must be some size threshold below which a
lump
of magnetite is not useful as a detector. It seems more likely
that
bacteria found it useful to sequester away iron in magnetite for
some
other reason, and then found a secondary sensory use for the
magnetite
crystals they found themselves making. I seem to remember Joe
Kirschvink making arguments along these lines. So its quite
feasible to
imagine the evolution of biological magnetite with no
magnetic field
to provide an environmental spur.
That said, Everett would probably have been better advised to
have said
"magnetites highly similar to those seen in magnetotactic
bacteria and
unlike any known non-biological forms".
Not that any of this means they are in fact bacterial.
best,
Oliver
=============
(10) METEORITE CONTAMINATION & A NULL HYPOTHESIS
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
Abstracts for the 'First Astrobiology Conference', held this week
at
NASA Ames Research Centre are online at
http://www.astrobiology.com/asc2000/program.html
The abstract of a paper by Andrew Steele et al. is below.
regards
Michael Paine
The Microbiological Contamination of Meteorites; A Null
Hypothesis
A. Steele, University of Portsmouth, UK, NASA Johnson Space
Center,
andrew.steele@easynet.co.uk;
K. Thomas-Keprta, NASA Johnson Space
Center; F. W. Westall, NASA Johnson Space Center; R. Avci,
Montana
State University; E. K. Gibson, NASA Johnson Space Center; C.
Griffin,
University of Liverpool, UK; C. Whitby, University of Liverpool,
UK; D.
S. McKay, NASA Johnson Space Center; J. K. W. Toporski, NASA
Johnson
Space Center
During in the course of our investigations into the microbial
contamination of meteorites (including ALH84001, Nakhla,
Murchison and
Allende) we have used 4 separate technique groups (Imaging,
Surface
analysis, microbial culturing and direct DNA isolation) to detect
the
presence of a wealth of heterotrophic microbial species.
Undoubtedly
the presence of these organisms in meteorites potentially has
grave
implications for the organic and inorganic species within these
meteorites. Experiments with a contaminated chip of the Murchison
meteorite show that bacteria can mediate significant damage to
the
surface of meteorites. Surface analysis shows that masses in the
mid
400 AMU range in meteorites exactly resemble those found in
terrestrial
biofilms and fossilised bacterial cells. By combining surface
specific
Time of Flight secondary Ion Mass Spectrometry of fresh fracture
surfaces followed by (after analysis), SEM imaging of the same
samples,
we have, in the case of ALH84001, been able to match certain high
mass
peaks in the mid 500 AMU range with cellular features and the 441
peaks
with what appears to be a polymeric coating on the surface. We
conducted
this analysis of a depth profile of ALH84001 and Nakhla and found
both
to contain possible biomarkers and in the case of Nakhla living
cells
all through the core of the meteorites. We have cultured several
organisms from Nakhla, ALH84001, Allende and Murchison and
completed
16srDNA analysis of a number of bacterial and fungal species from
Allende, by direct isolation of DNA from the meteorite.
In the case of ALH84001 the techniques used to deny the McKay et
al.,
(1996) hypothesis all failed to detect terrestrial
micro-organisms
living within the meteorite. This is an obvious cause for concern
in
the light of the Mars sample return mission. We contend that the
reason
for this is that meteorites become contaminated on immediate
contact
with the terrestrial biosphere at which time heterotrophic
microbial
species begin to reprocess any organic material within the
meteorite.
Subsequent analysis of the organic material would include
microbial
products as well as intrinsic organic material. Our conclusions
are
that a null hypothesis which states that ëall high molecular
weight
organic material in these meteorites is terrestrial in originí,
should
be applied to organic meteorite research. Undoubtedly this is not
the
case but it hoped that through this approach and this hypothesis,
we can
clarify the nature of any microbial action/contamination within
meteorites.
=============
(11) DOUBTS ABOUT VOLCANIC CATASTROPHE AD 536
From Steve Zoraster <szoraster@zycor.lgc.com>
Benny:
Although I enjoyed David Key's "Catastrophe: A Quest for the
Origins of
the Modern World," I ended up doubting the volcanic eruption
explanation at the end of the book. Among the scientific
"facts" I had
trouble with were:
1) The claim that "Up to ninety-six thousand cubic miles of
gas, water
vapor, magma, and rock were hurled into the atmosphere."
(Page 267 of
the American edition.) This sounds more like a Chicxulub scale
event
than a larger Tambora.
2) The lack of reported tsunami impacts recorded in already
literate
China, Japan, or India. Krakatoa killed mainly through a
tidal wave,
and it is hard to understand how an event so much larger, which
supposedly sundered Java from Sumatra, would not have caused a
much
larger tsunami, with results recorded across vast distances in
the
Pacific and Indian Oceans.
3) Fixing the date of the eruption at 535 when the calibrated C14
dates
are between 6600BC and 1300AD. (Note 1, Chapter 32. Page 316 of
the
American edition.)
By the way, I would like to ask Mr. Key about these issues, but
don't
know his e-mail. Can you or one of your readers help?
Steve Zoraster
=============
(12) SIXTH CENTURY "COMET" VECTOR
From Leroy Ellenberger < c.leroy@rocketmail.com
>
Dear Joel,
I read your comments in 5 April CCNet and offer the following
remarks:
1. I've read Saunders' review in New Scientist, but not Keys'
book, and
cannot imagine how Keys could go so far down the "volcano
road" in face
of the fact that there is no major volcanic acidity signal in the
Greenland ice cores at ca. A.D. 540 as there is a corresponding
acidity
signal in Greenland for every other known major volcanic eruption
in
the past 2000 years, while Baillie makes a good case in Exodus to
Arthur (1999), which was reviewed by New Scientist in their first
issue
for 1999, for a cosmic vector associated with the climate crisis
in the
sixth century.
2. The cosmic vector is NOT the close passage, or even an impact,
of a
comet, per se, but the cumulative effects of successive
atmospheric
accretion events over a number of years as Earth repeatedly
intercepts
large amounts of cometary debris from the dense portion of a
meteor
stream (in the case the Taurids, if Clube and Napier's model is
on
point, as I believe it is), whose most spectacular manifestation
would
be a succession of Tunguska-like detonations high in the
atmosphere
which greatly attenuates surface-level insolation. Baillie makes
the
case that much of the sixth century "dragon" lore
associated with
Arthur and Beowulf was inspired by such events, at which time
accounts
from China refer to dragons fighting at night and leaving the
forests
trampeled as they passed, which is not too bad for a
folk-impression of
a Tunguska-like event. Clube has documented the fact that every
period
of millennial or eschatological concerns in the past 2000 years
prior
to the 19th century, marked by portents in the sky, occurred at
times when Chinese records tell us the Taurid firefall flux was
enhanced. Cromwell rode the Taurid stream portents to fame and
lost
favor when the payoff did not turn out as he predicted. But this
aspect
of Cromwell's career is not dwelled upon recently nor evident in
the
1960s film "Cromwell". I invite you to read my
"Are Comets Evil?" at
the end of the file < http://abob.libs.uga.edu/bobk/velidelu.html
> for
more of the flavor of Clube & Napier's model and how its
impact on
culture has been largely overlooked, if not ignored.
Cheers,
Leroy Ellenberger
==============
(13) AND FINALLY: MEDIA BOO-BOO OF THE DAY
From Jeremy Tatum < UNIVERSE@uvvm.UVic.CA
>
RE: Will a Killer Asteroid Hit the Earth?
http://www.time.com/time/reports/v21/science/asteroid.html
Wow! The Arizona Meteor Crater is 34-miles wide! Gosh, I must go
down
and see that sometime!
Jeremy Tatum
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