PLEASE NOTE:
*
THE 1999 CCNet SURVEY
---------------------
Dear CCNet member,
I hope you have enjoyed the exciting developments and
lively debates which have featured on CCNet over the last
twelve months. Hardly a day has gone by without new
findings and reports of the booming fields of NEO research
and neo-catastrophism. We are obviously the participants
and witnesses of a major scientific revolution that is
overturning traditional views of the world in front of our
noses.
As we approach the end of this century and millennium,
humankind has finally become aware that our place in space
is far from perfect. In recent decades, we have been
forced to realise, not for the first time, that we
live in a precarious cosmic environment. This is a
sobering fact many tend to deny. Yet it is necessary to
accept this reality if we wish to respond to the perceived
threats adequatelty.
The intemperate optimism of the 19th century and its
doctrine of perpetual and unbroken progress is
certainly over. It is even more galling not to get
caught in the popular trap of doom and gloom. The
future of humankind and civilisation is wide open and
lies almost entirely in our own hands. I am confident that
this new alertness will focus our minds in the new century
even further so that adequate action can be taken to overcome
the cosmic challenge. Only then will we become the masters
of our own destiny.
On a more practical note, please find attached the end-of-year
CCNet Survey. I would very much appreciate it if you could
spare 3 minutes to answer the 13 questions listed below.
The results and responses will be published early next year.
May I take this opportunity to wish all list members all
the best for the festive season and a premature Happy New
Year!
Benny J Peiser
CCNet Moderator
----------------------
THE 1999 CCNet SURVEY
PLEASE RETURN COMPLETED QUESTIONNAIRE TO
b.j.peiser@livjm.ac.uk
----------------------
(1) Do you wish to continue your subscription
[ ] yes
[ ] no, please unsubcribe me from CCNet
(2) I read the CCNet
[ ] every day
[ ] from time to time
[ ] rarely
[ ] never
(3) Which are your main research areas/interests?
(tick all appropriate boxes)
[ ] SOLAR SYSTEM ASTRONOMY
[ ] NEO research, etc.
[ ] GEOLOGY, impact craters, etc
[ ] BIOLOGY, evolution, origins of life, etc.
[ ] PALEONTOLOGY, mass extinctions, etc.
[ ] ARCHAEOLOGY, CLIMATOLOGY, societal evolution, etc.
[ ] SPACE SCIENCE, space exploration, etc.
[ ] SCIENCE JOURNALISM
[ ] OTHERS:
(4) With view of your scientific interests, how would you
categorise the CCNet?
(tick all appropriate boxes)
[ ] very informative
[ ] too much popular, too little hard science
[ ] too much hard, too little popular science
[ ] very useful for my research
[ ] not really useful for my research
[ ] I find the abstracts service very helpful
[ ] quite interesting for its news and information
[ ] I don’t like the news items from the mass media
[ ] should be strictly limited to NEO research
[ ] too much chit-chat and debates
[ ] there could be more scientific debate
[ ] Less posting of controversies.
[ ] other comments…..
(5) Do you feel that during the last 12 months the quality of the
CCNet has
[ ] improved
[ ] remained the same
[ ] declined
(6) In view of the growing number of scientific mailing lists,
web
sites and discussion groups, do you think the
CCNet has become
superfluous?
[ ] yes
[ ] no
(7) In what way do you think the CCNet differs from other
science and astronomy networks and mailing
lists?
(8) Which CCNet features do you find particularly valuable?
(9) Which CCNet features do you find particularly inappropriate?
(10) Would you like to see any changes to the CCNet format?
(tick all appropriate boxes)
[ ] I like it just as it is
[ ] information should be limited to NEO research
[ ] I am only interested in abstracts and new publications
[ ] I am not interested in scientific debates
[ ] it should include broad information about all aspects
of neo-catastrophism and space
exploration
(11) Have you got any suggestions for change you feel
might help to improve the quality of the
CCNet?
(12) Do you sometimes utilise the internet archive of the CCNet
at http://abob.libs.uga.edu/bobk/cccmenu.html
?
[ ] frequently
[ ] sometimes
[ ] seldom
[ ] never
13) In one or two sentences, what is your general view about this
network?
THANK YOU FOR YOUR RESPONSE.
Please return the completed questionnaire to
b.j.peiser@livjm.ac.uk
*
CCNet, 10 December 1999
--------------------------------
QUOTE OF THE DAY
"Technology is a word which means
something that
doesn’t work yet"
-- Douglas Adams
http://www.bbc.co.uk/knowledge/thekit/06_kit.shtml
(1) TRUCKIE SAW MYSTERIOUS OBJECT CRASH INTO DAM
Benny J Peiser
(2) THERE IS AN ALIEN IN GURYA'S DRINK
Michael Paine <mpaine@tpgi.com.au>
(3) IT’S A METEORITE
Michael Paine <mpaine@tpgi.com.au>
(4) WATCHING GEMINIDS HIT THE MOON
NASA Science News <expressnews@sslab.msfc.nasa.gov>
(5) TUNGUSKA99: PRESS RELEASE
Luigi Foschini <foschini@tesre.bo.cnr.it>
(6) GRAVITATIONAL BILLIARDS DRIVES OUT ICE GIANTS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) BAKTERIA MAY THRIVE IN ANTARTIC LAKE
Andrew Yee <ayee@nova.astro.utoronto.ca>
(8) PROBABLE IMPACT CRATER OF HUMMELN, SWEDEN
M. Lindstrom et al., STOCKHOLM UNIVERSITY
(9) GEOPHYSICAL EVALUATION OF THE PROPOSED HUMMELN IMPACT CRATER
J. Ormo et al., UNIVERSITY OF STOCKHOLM
(10) METEORITIC SAMPLE OF ASTEROID IMPACT CRATER
D.A. Kring et al., UNIVERSITY OF ARIZONA
(11) IMPACT CRATERS ON MARS
N.A. Cabrol et al., NASA, AMES RES CTR
(12) IMPACT CRATERS ON ASTEROID MATHILDE
K.R. Housen et al., BOEING CO, SHOCK
PHYS GRP
(13) AND FINALLY: YULETIDE
Austen Atkinson <austen.atkinson@ultrazone.co.uk>
==============
(1) TRUCKIE SAW MYSTERIOUS OBJECT CRASH INTO DAM
From Benny J Peiser to Michael Paine, 9 December 1999
Dear Michael
I've just received the attached story, dated 12 September
1999. Perhaps you could be so good and check the source and
background of this weired report. Strange that we missed it
in the first place ......
Cheers, Benny
Linkname: Truckie saw mysterious object crash into dam
URL: http://news.ninemsn.com.au/01_national/story_10758.asp
5:26 am AEST September 12 1999 [actually 9 December 1999, BJP]
Truckie saw mysterious object crash into dam
AAP -- A truck driver today said he saw what appeared to be
a falling star on Monday night around the time a mysterious
object crashed into a northern New South Wales dam. The
town of Guyra is abuzz after an unidentified object crashed
into the local dam leaving a 90 square metre crater.
Truckie Wayne Petersen said he saw what looked like a
falling star shoot out of the sky around 9pm (AEDT) on
Monday. "I said to the girlfriend, look at the falling star
popped out of the sky," Mr Petersen told Sky News.
"It was blue in colour between the size of a golf ball and
a tennis ball and it came from an easterly direction." He
said it shot down on a 45 degree angle and beamed straight
over the horizon without burning out or changing colour.
"It was clear as daylight, you know, you could see it so
clean," he said.
Authorities said a mystery object crashed into the water
supply dam on the outskirts of the town, flattening reed
beds, some time between Monday and midday yesterday. Divers
from Sydney had been called to determine the size and
nature of the mystery object. Guyra Shire Council printed
leaflets overnight warning residents to conserve water and
urging them not to water gardens, wash cars or use
dishwashers. Tests on the water for toxins and radioactive
material were clear.
=================
(2) THERE IS AN ALIEN IN GURYA'S DRINK
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
It has been reported as a possible meteorite event but the
TV coverage showed a gouge rather than a crater, suggesting
a large horizontal component of velocity. This seems
unusual for a meteorite but I await scientific explanations
with interest.
Below is the Sydney Morning Herald report.
http://www.smh.com.au/news/9912/10/national/national2.html
Michael Paine
There's an alien in Guyra's drink
Date: 10/12/99
By GREG BEARUP
The concert pianist Roger Woodward looked from the
four-wheel-drive at where the unidentified flying object
had ploughed through reeds and into Guyra reservoir.
Woodward, who was in the northern New England town
yesterday looking at real estate, observed in a droll
voice: "Obviously, they are coming."
What police divers hope to find at the bottom of a
40-centimetre-diameter tunnel in the reservoir mud today
could shed more light on his prediction.
An excavator will be brought in to dig to the bottom of the
tunnel, discovered by divers when they inspected the impact
site yesterday.
Guyra, north of Armidale, has been in a frenzy since
Wednesday morning when Mr Peter Starr, who manages the
water treatment works, did his regular check of the
reservoir to ensure it was free of algae and that no stock
had broken in.
"Well, I seen where the reeds had been flattened and I
didn't know whathad caused it," he said. "I just knew
that
whatever it was it had fallen from the sky."
The object had flattened a patch a few metres wide and
about 15 metres long but Mr Starr said he didn't go into
the water for a closer look. "No bloody fear I didn't.
There's no future in that."
The UFO had plunged into the reservoir, about 10 kilometres
north of the town, between Mr Starr's inspection on Monday
and Wednesday morning.
After he reported the incident to the council the pumping
of water from the reservoir to the town was halted and
water restrictions were imposed.
Guyra is the highest northern town on the Great Dividing
Range and is used by the RAAF for dummy bombing runs.
Two F-111s have ploughed into the hills in the past 20
years but the local policeman, Sergeant Larry Hoffman, said
the Air Force insisted it had no planes in the area and
that all parts were accounted for.
"We really have no idea what caused it," he said,
joking
that he wouldn't mind if Sigourney Weaver emerged from the
swamp.
Some local SES volunteers armed with a pole waded into the
water, about 1.5 metres deep, and found that the object had
gouged a divot deeper than their pole.
Police divers flew in from Sydney to try to find the object
and tests were done to ensure that there was no radiation,
biological, bacterial or heavy metal contamination of the
water. It is expected that water supplies will resume
today.
Excitement is high but panic at a minimum in Guyra,
although there was a rush on bottled water at the
supermarket.
The town is, after all, home to a famous poltergeist, the
Guyra Ghost, which terrorised a local family in the 1920s
with white stones and voices from the ceiling.
---------
MORE UFO SIGHTINGS LIGHT UP
And here is some breaking news from the same newspaper:
More UFO sightings light up NSW skies
Source: AAP | Published: Friday December 10, 3:30 AM
The truth may be out there but in the meantime everyone is
indulging in a little speculation as new reports flood in
of UFOs crowding New South Wales skies.
Just a day after an unidentified object plunged into a dam
near the tiny rural hamlet of Guyra, council workers in
nearby Tamworth have reported an odd light in the sky.
The council workers reported seeing a flashing red glow for
about five minutes above Baldy Nob, 45km from their
Tamworth offices at 9.30am (AEST) on Wednesday.
They told the National Space Centre (NSC), which collates
reports of UFOs, that the red glow was flashing on and off
for about five minutes.
A NSC spokesman said they had also received 'about 110'
calls from other NSW residents reporting lights in the sky
or inquiring about the recent rash of sightings.
While UFO watchers are excited about the red glow (if it
was a reflection from the sun it would be white, they say)
a more scientific search will resume tomorrow to determine
what hit Guyra, about 145km north of Tamworth.
A meteorite, a piece of space junk, or even a chunk of
frozen urine from a passing plane are all being speculated
upon as the object which flattened reed beds and sprayed
mud as it plunged into the town's main water supply, some
time between Monday and midday yesterday.
But it made a bigger impact in the 2000-strong northern NSW
township which is enjoying the nationwide publicity visited
on their sleepy town.
Despite the best efforts of police divers the mysterious
object still has not been found. However, authorities
believe it is most likely a meteorite the size of a golf
ball.
The town's water was tonight given the all clear, test
results indicating there had been no contamination of the
water supply from whatever plunged into the dam.
But the water issue hasn't troubled locals, many say they
prefer drinking at the pub anyway. One of the few, but
growing number of witnesses to the landing, truck driver
Wayne Peterson, said he saw what appeared to be a falling
star shoot out of the sky about 9pm AEDT) on Monday night.
"It was blue in colour between the size of a golf ball and
a tennis ball and it came from an easterly direction,"
Peterson told Sky News.
=========
(3) IT’S A METEORITE
From Michael Paine <mpaine@tpgi.com.au>
Hi Benny, here is the latest from the Sydney Morning Herald
(10 Dec 1999 late afternoon):
FROM OUTER SPACE: IT'S A METEORITE
The mystery object that crashed into a northern New South
Wales dam was a small meteorite, police said today. Police
divers recovered sediment and fragments of the meteorite,
about the size of a golf ball, which penetrated the mud at
the bottom of the Guyra dam. It is embedded about four
metres into soft granite and cannot be removed, say police.
===============
(4) WATCHING GEMINIDS HIT THE MOON
From NASA Science News <expressnews@sslab.msfc.nasa.gov>
NASA Space Science News for Dec. 9, 1999
LunarImpact.com -- During November's Leonid meteor shower,
astronomers observed for the first time optical flashes
caused by meteorites striking the lunar surface. All were
relatively bright and easily detectable with amateur
telescopes. The next opportunity to view lunar meteorite
impacts could be just around the corner when the Geminid
meteor shower peaks on Dec. 14. LunarImpact.com features
information about the 1999 Leonid impacts, detailed
observing tips for the Geminids, and an
"Ask-a-lunar-observer" button sponsored by the
Association
for Lunar & Planetary Observers.
VISIT http://www.LunarImpact.com
for continuing coverage of things hitting the
Moon.
=================
(5) TUNGUSKA99: PRESS RELEASE
From Luigi Foschini <foschini@tesre.bo.cnr.it>
As one may remember, on the 29th of July 1999, Moscow customs
confiscated the rock and lacustrine sediment samples collected in
Tunguska (Central Siberia) by the "Tunguska99"
Scientific expedition.
The lack of the samples to be analyzed would make vain a great
part of
the human and financial efforts expended to achieve the
expedition.
The Department of Physics of Bologna University, in collaboration
with
the Moscow Research Institute of Aviation Systems (GosNIIAS) have
cleared up the numberous bureaucratic requirements necessary to
obtain
the release of the samples. Thanks to the efficiency of the
Russian
Authorities the samples left Moscow for Bruxelles on the 3rd of
December
1999 and were released to the Department of Physics on the 7-th
of
December 1999 after a brief inspection performed by Italian
customs in
the same morning.
At present, with a four month delay, it will be possible to begin
the
larger part of the analyses necessary to throw light on the
Tunguska
event, as was planned in the scientific programme of the
expedition.
For more informations and photos see:
http://www-th.bo.infn.it/tunguska/
Bologna, December 9, 1999
Tunguska99 Press Office
=================
(6) GRAVITATIONAL BILLIARDS DRIVES OUT ICE GIANTS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[http://helix.nature.com/nsu/991209/991209-9.html]
Thursday, 9 December 1999
Graviational billiards drives out ice giants
By PHILIP BALL
In Norse mythology, the Ice Giants were banished by Odin
and his brothers to the frozen outer regions of the world
beyond the realms of gods and men. Now a report in
Nature[1] suggests that something similar may have happened
in the early days of our Solar System -- recast in the
pantheon of the Greeks. The planets Jupiter and Saturn may
have cast the icy giant planets Uranus and Neptune into the
far-flung corners of the solar system.
Over the past four years the discovery of giant planets
around other stars has broadened the relevance of the
question: 'how do giant planets form?' Now that we know for
sure that our planetary system is not unique in the cosmos,
it is more than just idle musing to ask whether this system
is typical or not.
Our solar system can be considered as having three
neighbourhoods. The inner region, from Mercury to Mars,
contains the 'terrestrial' planets, rocky bodies with a
thin veneer of gases. Beyond Mars lie the gas giants:
Jupiter and Saturn, which are mostly composed of liquid
hydrogen below a thick layer of various gases. Yet further
out are two giant iceballs: Uranus and Neptune, along with
the smaller icy world of Pluto. All of these planets formed
from a disk of gas and dust -- the 'solar nebula' --
surrounding the young Sun.
So far, astronomical detection of planets around other
stars can pick up only very massive, Jupiter-sized,
planets. But this is not the only reason why the formation
of our own giant neighbours is of particular interest.
Surrounding the biggest of Earth's siblings there are still
many unanswered questions about how they were created in
the nascent solar system (see physics: Giant mistake, 18
November 1999, http://helix.nature.com/nsu/991118/991118-10.html).
One of the puzzles is that Uranus and Neptune sit in a
remote region of the solar system where the density of gas
and dust in the solar nebula would have been very low.
Where, then, did they find enough material to build two
planets over ten times the mass of the Earth?
Martin Duncan of Queen's University in Kingston, Canada,
and colleagues now propose that these two ice giants didn't
actually coalesce so far out at all. Computer simulations
indicate, they say, that Uranus and Neptune arose in the
dense gases surrounding Jupiter and Saturn, and were then
catapulted into the nether regions by the game of
gravitational billiards that went on in those early days of
the formation of our Solar System. The simulations predict
that these banished planets would then have wandered in
very erratic orbits for about a million years before
settling down.
The idea that there were several closely spaced
proto-planets in the early solar system gains more
credibility from independent work by Philip Armitage and
Brad Hansen of the University of Toronto, also reported in
Nature[2]. They have simulated the formation of giant
planets in the disk of gas and dust surrounding a young
star. They find that once one Jupiter-like gas-giant planet
forms in the disk, it can trigger the formation of others
within a narrow region. The giant planet effectively
shepherds matter within the nearby disk into clumps that
then evolve into new giant planets.
Armitage and Hansen believe that the gravitational
tug-of-war between this intimate group of planets would
then give rise to eccentric new non-circular orbits (rather
as Duncan and colleagues suggest happened to Uranus and
Neptune) which tends to force smaller planets to follow
suit. So what? Well, the more erratically moving giant
planets there are, the slimmer the chances are of
Earth-like planets achieving the kind of near-circular
orbit that would make them habitable.
[1] Thommes, E.W., Duncan, M.J. & Levison, H.F..The
formation of Uranus and Neptune in the Jupiter-Saturn
region of the Solar System Nature 402, 635 (1999).
[2] Armitage, P.J. & Hansen, B.M.S. Early planet formation
as a trigger for further planet formation Nature 402, 633
(1999).
© Macmillan Magazines Ltd 1999 - NATURE NEWS SERVICE
=================
(7) BAKTERIA MAY THRIVE IN ANTARTIC LAKE
From Andrew Yee <ayee@nova.astro.utoronto.ca>
National Science Foundation
Washington, D.C.
Media contact:
Peter West, (703) 306-1070, pwest@nsf.gov
Program contact:
Polly Penhale, (703) 306-1033, ppenhale@nsf.gov
Embargoed until 2 P.M. EST, December 9, 1999
NSF PR 99-72
Bacteria May Thrive in Antarctic Lake
Holds Implications for Search for Life in the Solar System
Two separate investigations of ice drilled at Lake Vostok,
a suspected body of subglacial water deep in the Antarctic
interior, indicate that bacteria may live thousands of
meters below the ice sheet. The findings by two National
Science Foundation-funded researchers are scheduled for
publication in the Dec. 10 issue of Science.
Two research teams, led by David M. Karl from the
University of Hawaii and John C. Priscu of Montana State
University, examined fragments of ice taken from roughly
3,600 meters (11,700 feet) below the surface -- about 120
meters (393 feet) above the interface of ice and suspected
water. Both teams found bacteria in "accreted" ice, or
ice
believed to be refrozen lake water.
The teams conclude that a potentially large and diverse
population of
bacteria may be present in the lake. If so, this bacteria answers
an
intriguing scientific question about whether an extremely cold,
dark
environment which is cut off from a ready supply of nutrients can
support life.
The DNA analysis by Priscu's team indicates that although the
bacteria
have been isolated for millions of years, they are biologically
similar
to known organisms. "Our research shows us that the
microbial world
has few limits on our planet," said Priscu. He added that
Lake Vostok
"is one of the last unexplored oases for life" on
Earth.
The teams also conclude microbes could thrive in other, similarly
hostile, places in the solar system. Lake Vostok is thought to be
an
analog to Europa, a frozen moon of Jupiter. Priscu notes in his
paper
that the Galileo spacecraft found evidence that liquid water
exists
under an icy crust on the Jovian moon. "Similar to ice above
Lake
Vostok, this ice may retain evidence for any life, if present, in
the
Europan ocean," he writes.
Evidence from radar mapping and other sources indicates that
under
several thousand meters of ice, liquid water may exist in Lake
Vostok,
possibly warmed by the pressure of the ice above or by thermal
features below. The lake is roughly the size of Lake Ontario in
North
America. Vostok Station -- a Russian scientific outpost, which
once
recorded the lowest temperature on earth (-126.9 degrees
Fahrenheit/
-89.9 degrees celsius) -- is located on the ice above the lake.
As part
of a joint U.S., French and Russian research project, Russian
teams
have drilled down into the ice covering the lake, producing the
world's deepest ice core. Drilling was deliberately stopped to
prevent introducing materials that would contaminate the water.
Karl notes at least one outstanding question about Lake Vostok:
whether the ice in which the bacteria were found is sufficiently
similar to the water in the lake to allow scientists to conclude
that a similar population -- or even larger, more diverse one --
might thrive in the suspected liquid water.
Delegates from several nations, including a U.S. delegation
sponsored
by NSF, met in England last September to decide whether and how
to
explore the suspected lake without contaminating it. No firm
proposal
has yet been accepted to accomplish that. "We don't know
what's
in Lake Vostok, and we may never know, if we don't get the
contamination issues solved," Karl said.
While the current findings may prove the existence of life in the
lake,
there are other scientific reasons to explore the lake itself.
Ice cores
have helped scientists assemble a climate record stretching back
more
than 400,000 years. Sediment samples from the bottom of Lake
Vostok
could extend that record to cover millions of years. "There
are other,
compelling reasons to go into the lake," Karl concluded.
IMAGE CAPTION:
[ http://www.nsf.gov/od/lpa/news/press/99/pr9972.htm
]
Microscopic Images of Bacteria Found in Melt Samples Taken from
Ice
Thought To Be Refrozen from the Waters of Lake Vostok. All photos
are
courtesy of David M. Karl, et al.
*****
Kathleen Burton
NASA Ames Research Center Dec. 9, 1999
Moffett Field, CA
(Phone: 650/604-1731, 650/604-9000)
kburton@mail.arc.nasa.gov
RELEASE: 99-81AR
ANTARCTICA'S FROZEN SLICE OF LIFE OFFERS CLUES TO LIFE ELSEWHERE
Scientists have
discovered a microbial world hidden deep beneath
the frozen Antarctic ice that could help them learn more about
how life
can survive under extreme conditions on other planets or moons.
Their findings are featured in a research paper co-authored by
Dr.
Chris McKay, a planetary scientist at NASA Ames Research Center,
Moffett
Field, CA, which will be published in the Dec. 10 issue of
Science
magazine. Co-authored by a multi-disciplinary science team,
the research
paper entitled "Geomicro-biology of Subglacial Ice Above
Lake Vostok,
Antarctica," analyzes the ice above Lake Vostok, a huge
freshwater lake
buried deep below the East Antarctic ice sheet.
"Microbes within the liquid water habitat of Lake Vostok may
shed
light on the viability of life in similar harsh environments
beyond Earth,
such as in the frozen ocean subsurface on Jupiter's moon,
Europa,"
McKay said. Galileo spacecraft results imply that a
subsurface ocean
could exist on Europa.
The research team tested samples from the ice 3,590 meters below
Vostok Station, and found diverse colonies of microbes.
Scientists say
this is significant because the lake has been isolated from the
usual
sources of atmospheric-derived energy, such as photosynthesis,
for
millions of years.
"How the bacteria get energy (to survive) is an important
question,"
McKay said. "The lake could be an analog to sub-ice
Europa or subsurface
Mars where conditions are similar. "
Scientists believe ice is a good environment for primitive
bacteria.
The bacteria need less food because it's cold, and its metabolism
slows
down, somewhat like a hibernating bear's. Another finding
was that DNA
extracted from the microbes present in the team's Lake Vostok
sample
indicated the presence of only a few subgroups of known bacteria,
coupled
with low overall microbial diversity.
"It's what you'd expect, not teeming with rich life,"
McKay said.
The team also found signs of bacterial life in the ice core and
detected
metabolic activity in some of the bacteria by measuring the
bacteria's
respiration rates during incubation.
Scientists said the sampled Vostok glacier ice also suggested
that
the lake water derived from a mixture of melted ice from both
glacial and
interglacial periods, deposited there approximately one million
years ago.
Although the thickness of the ice on Europa is not known,
scientists
think that tidal forces could form cracks extending to the
surface. Under
the thin ice, conditions may be similar to the conditions at Lake
Vostok.
"If a similar ice layer is present under the surface of
Europa's icy
oceans, it may also harbor life," said McKay.
The research team included the paper's lead author, Dr. John
Priscu,
and others from the departments of Biology, Earth Science and
Physics
at Montana State University, Bozeman, MT. Other researchers
were from
the department of Geology, the University of Alabama, Tuscaloosa,
AL
and the U. S. Geological Survey, Reston, VA.
=================
(8) PROBABLE IMPACT CRATER OF HUMMELN, SWEDEN
M. Lindstrom*), T. Floden, Y. Grahn, S. Hagenfeldt, J. Ormo,
E.F.F. Sturkell, R. Tornberg: The Lower Palaeozoic of the
probable
impact crater of Hummeln, Sweden. GFF, 1999, Vol.121, No.Pt3,
pp.243-252
*) STOCKHOLM UNIVERSITY,DEPT GEOL & GEOCHEM,SE-10691
STOCKHOLM,SWEDEN
A 1.2 km wide, sub-circular hole in Lake Hummeln (57 degrees
22'N, 16
degrees 15'E) has been suggested to be an impact crater. The lake
has
furthermore been suspected to contain an outlier of Cambrian and
Ordovician sedimentary rocks. A shallow seismic survey, followed
by
core drilling to 164.25 m below the lake surface, demonstrated
the
presence of a strongly slumped succession consisting, from below,
of
shattered crystalline basement rock, Lower and Middle Cambrian
sandstone and claystone, Lower Ordovician limestone, and Middle
Cambrian claystone. The lithogenesis and original stratigraphy
are
closely similar to coeval bale on Oland 40 km to the east. Dating
was
done through acritarchs in the Cambrian, and through conodonts
and
chitinozoans in the Ordovician. An impact is postulated although
no
quartz with PDF has been identified in the available lithologies.
The
drilling had to stop, apparently without reaching the crater
floor.
If dated by the oldest sediments present, the impact would be
Early
Cambrian. A late Early or early Middle Ordovician age, however,
is
more likely because slumping after impact filled the crater with
sediments aged Lower Cambrian through Lower Ordovician, and
because
the slumped sediments bear evidence of not having been originally
deposited in a crater. Copyright 1999, Institute for Scientific
Information Inc.
============
(9) GEOPHYSICAL EVALUATION OF THE PROPOSED HUMMELN IMPACT CRATER
J. Ormo*), E. Sturkell, G. Blomqvist, R. Tornberg: Mutually
constrained geophysical data for the evaluation of a proposed
impact
structure: Lake Hummeln, Sweden. TECTONOPHYSICS, 1999, Vol.311,
No.1-4, pp.155-177
*) UNIVERSITY OF STOCKHOLM,DEPT GEOL & GEOCHEM,S-10691
STOCKHOLM,SWEDEN
Lake Hummeln covers a 1.2-km-wide near-circular depression in the
Precambrian basement of the Baltic Shield. In the depression,
more
than 150 m thick Cambrian and Ordovician marine sediments are
underlain by non-volcanic breccia. The only explanation that does
not
meet contradictions is that the structure was caused by impact,
but
evidence of shock metamorphism is until now missing. This study
focuses on the geophysical characterisation and includes magnetic
and
gravimetric modelling, constrained by information from
resistivity
measurements, geological mapping and a drill core. The Hummeln
structure shows both a gravimetric and a magnetic low. The
magnetic
low is not broken by any short wavelength anomalies which would
indicate the presence of remanent melt occurrences. The diameter
of
the magnetic low is about twice that of the proposed crater
depression, and probably indicates fracturing. Both the magnetic
and
the gravimetric models show a structure that is consistent with
the
impact hypothesis. Resistivity measurements were carried out in
the
surroundings of the proposed crater. The fractured region
indicated
by the magnetometry does not produce a detectable resistivity
anomaly. However, resistivity measurements proved useful in
investigating the tectonic fracture zones crossing the area in
the vicinity of the structure. Following the impact model, a
reconstruction of the pre-erosional structure resulted in an
approximately 50% wider original crater than seen today. (C)
1999 Elsevier Science B.V. All rights reserved.
============
(10) METEORITIC SAMPLE OF ASTEROID IMPACT CRATER
D.A. Kring*), D.H. Hill, J.D. Gleason, D.T. Britt, G.J.
Consolmagno,
M. Farmer, S. Wilson, R. Haag: Portales Valley: A meteoritic
sample of
the brecciated and metal-veined floor of an impact crater on an
H-chondrite asteroid. METEORITICS & PLANETARY SCIENCE, 1999,
Vol.34,
No.4, pp.663-669
*) UNIVERSITY OF ARIZONA,LUNAR & PLANETARY
LAB,TUCSON,AZ,85721
A shower of meteorite fragments fell at similar to 0730 h local
time
on 1998 June 13 near the town of Portales, New Mexico. Thus far,
51
pieces of the Portales Valley (H6) meteorite have been recovered.
This meteorite has an unusually large number of metallic veins.
Some
of these veins are also unusually thick, having widths on the
order
of centimeters. These wide veins have fine Widmanstatten
structure,
which is the first time it has been seen in an ordinary
chondrite.
This structure indicates the metallic veins and the host
chondrite
cooled slowly. These veins appear to have been produced by shock-
metamorphic processes, which we infer produced a >20 km
diameter
impact crater on an H-chondrite planetesimal. Copyright 1999,
Institute for Scientific Information Inc.
==============
(11) IMPACT CRATERS ON MARS
N.A. Cabrol*), E.A. Grin, H.E. Newsom, R. Landheim, C.P. McKay:
Hydrogeologic evolution of Gale crater and its relevance to the
exobiological exploration of Mars. ICARUS, 1999, Vol.139, No.2,
pp.235-245
*) NASA, AMES RES CTR,SETI,CTR MARS EXPLORAT,MS 239-20,MOFFETT
FIELD,CA,94035
The presence of an Amazonian impact crater lake in the Noachian
crater Gale (located in the Aeolis northwest subquadrangle of
Mars)
is indicated by evidence from young floor deposits, streamlined
terraces, layers, and channels observed on the central
sedimentary
deposit. Evidence for the filling of this lake by two processes
is
described: (a) the drainage of the aquifer in the Aeolis Mensae
region, supported by extended mass-wasting and rim sliding in the
crater at the contact with the mensae and (b) the overspilling of
the
northern rim by an Amazonian south transgression of the Elysium
Basin. This last hypothesis is supported by hydrologic features
such
as channels and channel-like depressions north of the crater and
by
the crescent-like shape of the central sedimentary deposit. The
presence of an impact melt sheet and uplifted central peak may
have
also generated hydrothermal activity, including an early crater
lake,
shortly after the formation of the crater in the Noachian period.
With time, decreasing heat flux, and changing climates Gale may
have
experienced transitions in aqueous environments from warm and wet
to
cold and ice-covered water that could have provided suitable
eases
for various communities of microorganisms. Preservation of the
biological and climatic record may have been favored in this
paleolacustrine environment, which probably occured episodically
over
two billion years. (C) 1999 Academic Press.
===============
(12) IMPACT CRATERS ON ASTEROID MATHILDE
K.R. Housen*), K.A. Holsapple, M.E. Voss: Compaction as the
origin of the unusual craters on the asteroid Mathilde.
NATURE, 1999, Vol.402, No.6758, pp.155-157
*) BOEING CO, SHOCK PHYS GRP, MS 8H-05, POB 3999, SEATTLE,
WA, 98124
The asteroid Mathilde has suffered at least five giant
impacts. Previous studies suggest that Mathilde's giant
craters should be surrounded by blankets of ejecta that are
kilometres deep(1,2), yet the craters show no evidence of
filling by material excavated during later nearby
impacts(1,3). Computer simulations of impacts have been
used to suggest that the absence of ejecta arises because
the impact energy is deposited in a small volume, due to
Mathilde's unusually high porosity(4), which produces
ejecta velocities so high that nearly all of the material
escapes Mathilde's gravitational field(5). Here we report
laboratory measurements of high-velocity impacts into
porous material, which support an alternative
explanation(3): the crater is formed mainly by compaction,
not excavation. The small amount of ejecta lofted in our
experiments have velocities sufficiently low that nearly
all of the material is redeposited within the crater bowl.
The crater itself results from material being compressed,
rather than ejected. This type of cratering implies that
highly porous asteroids are minor contributors of
meteorites, because essentially no material escapes the
asteroids. Copyright 1999, Institute for Scientific Information
Inc.
==============
(13) AND FINALLY: YULETIDE
From Austen Atkinson < austen.atkinson@ultrazone.co.uk
>
Benny,
I would like to wish all those who share in your extremely
valuable
Cambridge Conference Network, a very Merry Christmas. Let us hope
that 2000 AD proves to be a breakthrough year for public
awareness of
this issue and for increased funding of NEO research.
Austen Atkinson
Author 'Impact Earth'
<austen.atkinson@ultrazone.co.uk>
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