PLEASE NOTE:


*

CCNet 4/2003 -  14 January 2003
------------------------------


"How many of Earth's five great extinctions were sparked by
asteroids or comets? Was the catastrophic impact linked to the dinosaurs'
demise 65 million years ago unique? University of Washington paleontologist
Peter Ward hinted that might be the case at this week's meeting of
the American Astronomical Society - but a Cosmic Log item about his talk had
what you could call a deep impact among some who keep track of past global
catastrophes."
--Alan Boyle, Cosmic Log, 10 January 2003


"I wanted to let you know that the comment by Peter Ward about
replication of our results (this is our work he is referring to) is not
true. Nobody has attempted to replicate our results. It's unfortunate,
but sometimes this is the way science goes ... there will be
someone that will attempt to replicate our work and the truth will come
out."
--Luann Becker, University of California at Santa Barbara


"Peter Ward's statement on the Uniqueness of the K-T impact, which
implies that there is no evidence for any other mass extinction
linked to a large impact, must be considered as bizarre and is
simply wrong on all kinds of evidence that has accumulated. The Universe is
a shooting gallery with Target Earth being hit at random intervals that obey
a scientifically known or at least knowable probability law. These are
positive probabilities large enough for at least one global killer event
being expected once about every 100 Ma. It would be an extraordinary
coincidence if Peter Ward is correct that it happened only once, at the
65 Ma K-T catastrophe."
--Hermann Burchard, Oklahoma State University


(1) NEW MOONS FOUND AROUND NEPTUNE
    Ron Baalke <baalke@zagami.jpl.nasa.gov>

(2) HOW MANY MASS EXTINCTIONS WERE CAUSED BY GIANT IMPACTS?
    Alan Boyle's Cosmic Log, 10 January 2003

(3) SMART-1 AND ROSETTA MISSION MAY HAVE TO BE DELAYED
    BBC News Online, 13 January 2003

(4) COMET-CHASING MISSION CONSIDERS ALTERNATIVES
    New Scientist, 13 January 2003

(5) PLASMA PROBE SCIENTISTS REDAY FOR ROSETTA BLAST-OFF
    Ron Baalke <baalke@zagami.jpl.nasa.gov>

(6) NASA SUCCESSFULLY LAUNCHES ICE TRACKING SATELLITE
    BBC News Online, 13 January 2003

(7) WAS THE K-T EVENT A ONE-OFF?
    Hermann Burchard <burchar@math.okstate.edu>

(8) RETURN TO THE MOON
    Richard Taylor <richard.taylor3@virgin.net>

(9) TUNGUSKA & THE 1953 LUNAR FLASH
    Jens Kieffer-Olsen <dstdba@post4.tele.dk>

(10) RE: NEXT TUNGUSKA CLASS RISK
     Andy Smith <astrosafe22000@yahoo.com>

(11) AND FINALLY: "WE DON'T WANT ANY JUNK IMPACT CRATERS IN OUR
NEIGHBORHOOD"
     Ron Baalke <baalke@zagami.jpl.nasa.gov>


============
(1) NEW MOONS FOUND AROUND NEPTUNE

>From Ron Baalke <baalke@zagami.jpl.nasa.gov>

http://cfa-www.harvard.edu/press/pr0303.html

Harvard-Smithsonian Center for Astrophysics
Press Release No.: 03-03
For Release: January 13, 2003

New Moons Found Around Neptune

Cambridge, MA - A team of astronomers led by Matthew Holman
(Harvard-Smithsonian Center for Astrophysics) and JJ Kavelaars (National
Research Council of Canada) has discovered three previously unknown moons of
Neptune. This boosts the number of known satellites of the gas giant to
eleven. These moons are the first to be discovered orbiting Neptune since
the Voyager II flyby in 1989, and the first discovered from a ground-based
telescope since 1949.

It now appears that each giant planet's irregular satellite population is
the result of an ancient collision between a former moon and a passing comet
or asteroid. "These collisional encounters result in the ejection of parts
of the original parent moon and the production of families of satellites.
Those families are exactly what we're finding," said Kavelaars.

The team that discovered these new satellites of Neptune includes Holman and
Kavelaars, graduate student Tommy Grav (University of Oslo &
Harvard-Smithsonian Center for Astrophysics), and undergraduate students
Wesley Fraser and Dan Milisavljevic (McMaster University, Hamilton, Ontario,
Canada).

Needle in a Haystack

The new satellites were a challenge to detect because they are only about
30-40 kilometers (18-24 miles) in size. Their small size and distance from
the Sun prevent the satellites from shining any brighter than 25th
magnitude, about 100 million times fainter than can be seen with the unaided
eye.

To locate these new moons, Holman and Kavelaars utilized an innovative
technique. Using the 4.0-meter Blanco telescope at the Cerro Tololo
Inter-American Observatory, Chile, and the 3.6-meter Canada-France-Hawaii
Telescope, Hawaii, they took multiple exposures of the sky surrounding the
planet Neptune. After digitally tracking the motion of the planet as it
moved across the sky, they then added many frames together to boost the
signal of any faint objects. Since they tracked the planet's motion, stars
showed up in the final combined image as streaks of light, while the moons
accompanying the planet appeared as points of light.

Prior to this find, two irregular satellites and six regular satellites of
Neptune were known. The two irregular satellites were also the largest:
Triton, discovered in 1846 by William Lassell, and Nereid, discovered in
1949 by Gerard Kuiper. Triton is considered irregular because it orbits the
planet in a direction opposite to the planet's rotation, indicating that
Triton is likely a captured Kuiper Belt Object. (The Kuiper Belt is a
disk-shaped collection of icy objects that circle the Sun beyond the orbit
of Neptune.) Nereid is considered irregular because it has a highly
elliptical orbit around Neptune. In fact, its orbit is the most elliptical
of any satellite in the solar system. Many scientists believe that Nereid
once was a regular satellite whose orbit was disrupted when Triton was
gravitationally captured. The six regular satellites were discovered by the
Voyager probe during its encounter with Neptune. The three new satellites
were missed by Voyager II because of their faintness and great distance from
Neptune. According to Holman, "The discovery of these moons has opened a
window through which we can observe the conditions in the solar system at
the time the planets were forming."

Tracking Faint Blips

The researchers are currently conducting follow-up observations to better
define the orbits of the newfound moons using orbital predictions supplied
by Brian Marsden (Director of the Minor Planet Center in Cambridge, Mass.)
and Robert Jacobson (Jet Propulsion Laboratory).

To follow up the initial find, team members Brett Gladman (University of
British Columbia, Canada); Jean-Marc Petit, Philippe Rousselot, and Olivier
Mousis (Observatoire de Besancon, France); and Philip Nicholson and Valerio
Carruba (Cornell University) conducted additional observations using the
Hale 5-meter telescope on Mount Palomar and one of the four 8.2-meter
telescopes of the European Southern Observatory's Very Large Telescope at
Paranal Observatory, Chile. Grav made additional tracking observations using
the 2.6-meter Nordic Optical Telescope on La Palma, Spain.

Holman says, "Tracking these moons is an enormous, international undertaking
involving the efforts of many people. Without teamwork, such faint objects
could be easily lost."

Based in La Serena, Chile, the Cerro Tololo Inter-American Observatory is
part of the National Optical Astronomy Observatory, which is operated by the
Association of Universities for Research in Astronomy, Inc., under a
cooperative agreement with the National Science Foundation.

The Canada-France-Hawaii Telescope is operated by the CFHT Corporation under
a joint agreement between the National Research Council of Canada, the
Centre National de la Recherche Scientifique of France, and the University
of Hawaii.

The European Southern Observatory is an intergovernmental, European
organization for astronomical research. It has ten member countries. ESO
operates astronomical observatories in Chile and has its headquarters in
Garching, near Munich, Germany.

Headquartered in Cambridge, Massachusetts, the Harvard-Smithsonian Center
for Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists organized into six research divisions study the origin,
evolution, and ultimate fate of the universe.

Note to editors: An image of one of the three new Neptunian moons is
online at http://cfa-www.harvard.edu/press/pr0303_image.html.

For more information and list of extra-solar planetary experts, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
daguilar@cfa.harvard.edu

Christine Lafon
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
Phone: 617-495-7463, Fax: 617-495-7016
clafon@cfa.harvard.edu

=============
(2) HOW MANY MASS EXTINCTIONS WERE CAUSED BY GIANT IMPACTS?

>From Alan Boyle's Cosmic Log, 10 January 2003
http://www.msnbc.com/news/750150.asp?0si=-

Doomsday revisited: How many of Earth's five great extinctions were sparked
by asteroids or comets? Was the catastrophic impact linked to the dinosaurs'
demise 65 million years ago unique?
       
University of Washington paleontologist Peter Ward hinted that might be the
case at this week's meeting of the American Astronomical Society - but a
Cosmic Log item about his talk had what you could call a deep impact among
some who keep track of past global catastrophes.

Hermann Burchard, a math professor at Oklahoma State University, wrote in
that Ward's claim was "simply wrong on all kinds of evidence."

He cited research published this year that pointed to a link between a
potential asteroid impact and the Triassic-Jurassic extinction 200 million
years ago. Ken Lord of Victoria, British Columbia, pointed to the same event
and cited past speculation tracing the catastrophe to whatever caused the
Manicouagin Crater in Quebec. (However, that crater has been dated to 214
million years ago, not quite in the same time range.)

Ward himself has studied the Triassic-Jurassic event and reported in 2001
that the die-off apparently occured in a geological blink of the eye.

Burchard also pointed to the linkage between an ancient upheaval in the West
Siberian Plane and the mother of all extinctions, the Permian-Triassic event
250 million years ago. This year, researchers reported that the Siberian
volcanic outflow stretched over an area half the size of Australia - but
Ward said the event didn't fit the profile for an asteroid or comet impact.

I also heard from Luann Becker, a professor at the University of California
at Santa Barbara whose research hints at a link between the Permian-Triassic
extinction and a space impact.

Becker and her colleagues analyzed cagelike carbon molecules, known as
buckyballs or fullerenes, that were recovered from 250-million-year-old rock
samples. Trapped within the buckyballs were helium and argon molecules that
hinted at an outer-space origin.

Ward said this week that the buckyball results had not yet been replicated -
a statement that naturally bothered Becker.

"I wanted to let you know that the comment by Peter Ward about replication
of our results (this is our work he is referring to) is not true. Nobody has
attempted to replicate our results," she wrote. "It's unfortunate, but
sometimes this is the way science goes ... there will be someone that will
attempt to replicate our work and the truth will come out."

In last March's issue of Scientific American, she acknowledged that the
linkage between cosmic impact and mass extinction wasn't as strong as it was
for the dinosaur-killing blast at the end of the Cretaceous era.

"It is important to note, however, that the impact tracers that typify the
end of the Cretaceous will not be as robust in rocks linked to older mass
extinctions," she wrote.

You can get the latest dirt on cosmic catastrophes and the speculation
surrounding them at the Cambridge Conference Network.

Meanwhile, other Cosmic Log readers speculated about future catastrophes and
what they would mean for humanity. Check out the latest feedback file for a
selection of letters about the ends of the world as we know it.

Copyright 2003, MSNBC

==============
(3) SMART-1 AND ROSETTA MISSION MAY HAVE TO BE DELAYED

>From BBC News Online, 13 January 2003
http://news.bbc.co.uk/2/hi/science/nature/2654659.stm

Europe's ambitious mission to land a probe on the surface of a comet is
likely to launch on 22 January.

Scientists working on the Rosetta mission told journalists in London on
Monday they were hopeful of meeting the date - or one just a few days later.

A final decision is expected in the next 48 hours.

"I hope we will get Rosetta soon off the ground and we don't have to wait
for much longer to get the return on our investment in this excellent
science," said Dr Gerhard Schwehm, Rosetta's project scientist.

He said the chance of a successful mission, including launch, was "above
90%".

Standard rocket

The spacecraft should have flown at the weekend but the high-profile failure
of Europe's new super rocket, the Ariane 5-ESCA, led to all Rosetta
preparations being suspended.

Although investigators think they know the cause of the failure, they wanted
to satisfy themselves that there were no implications for the £600m (one
billion euros) comet mission, which is due to launch on a standard version
of the vehicle.

Engine glitch brought down rocket

All inquiries should be complete by tomorrow and the European Space Agency
(Esa) is expected to give Rosetta the formal green light on Wednesday.

The agency is under immense pressure to get the comet mission up.

High speed

The spacecraft must perform a complex series of manoeuvres around Earth and
Mars to achieve the speed it needs to catch up with Comet Wirtanen.

Even then, it will be 2011 before Rosetta reaches Wirtanen and 2012 before
it places a lander on the surface of the comet.

But the narrow launch window closes at the end of January. If Rosetta fails
to fly, Esa will have to find an alternative target, which may not be
possible.

Dr Schwehm said 22 January was the earliest Rosetta could launch.

He told the BBC there were three other options to go on the 23rd, 26th or
29th - but after that it would be too late.

Moon mission

It emerged on Monday that another Esa space venture could be delayed by the
rocket set-back.

Europe is sending an unmanned spacecraft to map the Moon early in 2003. The
mission, Smart-1, is due to be launched in March.

A British scientist on the project, Professor Manuel Grand of the Rutherford
Appleton Laboratory in Oxfordshire, said the take-off date might slip
because of the Ariane 5 problems.

"We're still officially launching on 21 March but I wouldn't be surprised if
we had a couple of months' delay," he told BBC News Online.

Copyright 2003, BBC

============
(4) COMET-CHASING MISSION CONSIDERS ALTERNATIVES

>From New Scientist, 13 January 2003
http://www.newscientist.com/news/news.jsp?id=ns99993259
   
A handful of comets are being intensely studied as possible replacement
targets for the first space mission designed to orbit and land on such a
body.

Comet Wirtanen, the original target of the European Space Agency's Rosetta
mission, could be out of range by the time the craft is given the all-clear
for launch. Rosetta should have lifted off on 12 January, but in December an
upgraded version of the rocket that will carry it self-destructed after
veering off course.

An investigation by Arianespace, which operates the Ariane 5 rocket,
suggests that the failure was caused by a new component that will not be
used in the standard configuration used to launch Rosetta. But they will not
make a final decision until Tuesday.

If the rocket is cleared for launch, the most likely date is 22 January,
eight days before the 30 January deadline. If not, the Rosetta spacecraft
will have to seek a new comet to catch and explore.

Slingshot manoeuvre

Sue Horne, at the UK Particle Physics and Astronomy Research Council, says
between four and six possible replacement comets are currently being
examined. A final choice, if necessary, would be made on the basis of the
expected scientific returns.

Gerhard Schwehm, Rosetta project scientist at ESA, says: "It is possible it
will not launch [on time]. There are a handful of comets we can reach, but
we really have to look at the merits of each."

The Rosetta probe is intended to rendezvous with comet Wirtanen at a point
in space six times further away from the Sun than the Earth. But to do this
it must perform a complex series of slingshot orbits around Mars and the
Earth. If the mission is delayed beyond the deadline, the comet will be out
of reach.

The mission is estimated to have cost a total of 1 billion Euros, but
retargeting it would cost many more million Euros.

Dirty snowball

Comets are thought to be comprised of mainly rock and ice, but are not well
understood. By orbiting and landing on comet, the Rosetta mission could help
scientists better understand the origins of the Solar System and how water -
and even life - arrived on Earth.

Rosetta has 11 different scientific instruments that will capture images and
analyse dust samples from an orbit around the comet. A 3-D radio wave
instrument will probe the composition of the comet's nucleus. A suite of
plasma sensors will analyse the comet's interaction with the electrically
charged particles of the solar wind.

After a suitable landing spot has been identified, the spacecraft's lander
will make its approach, travelling alongside its target at around 40
kilometres per second. The lander will then fire a harpoon to attach itself
to the comet's surface and will take samples to determine the comet's
chemical composition.
 
Will Knight

Copyright 2003, New Scientist

============
(5) PLASMA PROBE SCIENTISTS REDAY FOR ROSETTA BLAST-OFF

>From Ron Baalke <baalke@zagami.jpl.nasa.gov>

http://www.imperial.ac.uk/templates/text_3.asp?P=3803

For Immedidate Use

Plasma probe scientists ready for Rosetta blast-off
Imperial College of Science, Technology and Medicine
January 13, 2003

Scientists who built and will control the instruments to investigate plasma
changes around a comet describe their contribution to the ten year long
mission at a pre-launch press briefing in London today (Monday 13 January).

While the actual launch date for the European Space Agency's Rosetta mission
has yet to be confirmed, the scientists, engineers and technicians behind
the plasma-detecting instruments on board the spacecraft are all ready to
begin the journey to comet Wirtanen they hope will return a rich scientific
bounty.

"We're not very familiar with plasma here on Earth, but it does exist all
around us, for example, in fluorescent lights or the flame of a match. It's
simply a gas which has become electrically charged," says Chris Carr,
spokesman for the Rosetta Plasma Consortium instruments, based at Imperial
College London.

"Outside the confines of our atmosphere on earth, the vacuum of space is
filled with a very, very dilute plasma - maybe only a thousand atoms in each
litre of space."

The Rosetta Plasma Consortium has built highly sensitive instruments capable
of detecting and measuring the properties of this diffuse plasma.

The sensors will be switched on well before the cameras are able to see any
activity on the surface of the comet, making it likely that plasma
instruments will be one of the first to detect the telltale signature of the
comet.

The Plasma Consortium's chief interest is to learn how the solar wind - a
stream of plasma that flows out from the Sun and fills the Solar System -
interacts with the comet itself.

"A lot of the gas which comes off the comet is actually turned into plasma
by the action of the strong ultra-violet light from the Sun," explains Mr
Carr.

"So there is a source of plasma pushing outwards from the comet which meets
the solar wind head on, producing a 'bubble' of comet plasma in a sea of
solar wind."

The plasma instruments will study the structure of this bubble, which
measures about a million kilometres wide, and compares with a nucleus size
of the comet of just one kilometre.

"One of the things we're really excited about is that we will be monitoring
the comet over a long period of time, so we will be able to watch as the
comet activity goes from nothing to a really strong outflow of material,"
says Mr Carr.

The plasma instruments weigh just over 7kg, and because Rosetta is far out
in deep space, with very little sunlight shining on the solar panels, have
been designed to consume less than a quarter of the power of a single light
bulb.

The plasma investigation will be carried out by a group of five instruments
built by space researchers from Sweden, Germany, France, USA and the UK.

Scientists at Imperial College London built the Plasma Interface Unit - the
'nervous system' - that links up the five ultra-sensitive plasma-detecting
probes aboard Rosetta (See notes to editors).

Assuming a successful Rosetta launch before the end of January 2003, theirs
will be the first scientific instrument to be turned on at the
'commissioning' stage due to take place from February at the European Space
Agency operations centre in Darmstadt, Germany.

The PIU itself weighs about 3kg and is the size of two shoe boxes on top of
each other, and has been the focus of a number of technical innovations.

"Developing this unit, the 'nervous system' for the plasma instruments, was
a constant balancing act between miniaturisation to save space and weight
and maintaining its reliability to give continuous operation in space for
ten years," says Dr Chris Lee, Rosetta Plasma Consortium Operations Manager,
based at Imperial College London.

For example, the walls of the box were machined down from sheets of
aluminium 2.54 centimetres (an inch) thick to just 0.3mm in places - a
machining task that required a new technical innovation from Ray Swain, head
of the Department of Physics workshops, as standard techniques left the
metal warped.

Scientists from Imperial's Space and Atmospheric Physics Group have
extensive experience in building and operating plasma instruments aboard
space missions including those that have flown on the Cluster mission around
Earth, the Cassini mission to Saturn, the Double Star mission around Earth
and the Ulysses mission to the Sun.

The Imperial team behind the PIU was recently promoted from Co-Investigator
to Principal Investigator status.

                                     ###

For more information and pictures please contact:

Chris Carr
Rosetta Plasma Consortium spokesman
Department of Physics
Imperial College London
Tel: 44-207-594-7765
E-mail: c.m.carr@imperial.ac.uk

Dr Chris Lee
Rosetta Plasma Consortium Operations Manager
Department of Physics
Imperial College London
Tel: 44-207-594-7762
E-mail: c.g.y.lee@imperial.ac.uk

Tom Miller
Imperial College London Press Office
Tel: 44-207-594-6704
Mobile: 44-780-388-6248
E-mail: t.miller@imperial.ac.uk

===========
(6) NASA SUCCESSFULLY LAUNCHES ICE TRACKING SATELLITE

>From BBC News Online, 13 January 2003
http://news.bbc.co.uk/1/hi/sci/tech/2653503.stm
 
A satellite that will track the changes in the major ice sheets covering the
polar regions was launched on Sunday.

ICESat (Ice Cloud and Land Elevation Satellite) was blasted into orbit on a
Delta rocket from Vandenberg US Air Force Base on the central California
coast.

The spacecraft will give scientists the clearest picture yet of what is
really happening in the Arctic and the Antarctic - whether the ice there is
shrinking or growing and by how much, and the impact these changes might
have on global sea levels.

"The geophysical community has been waiting for ICESat for 30 years," US
space agency researcher Eric Rignot, who studies Antarctic ice, has told the
BBC.

ICESat should have gone up last month. Its launch has been delayed by
technical problems.
 
The double payload was carried on a Delta II rocket

It went up as part of a dual payload - a common occurrence these days as
launch companies attempt to drive down costs in a competitive but depressed
satellite market - at 1645 PST (0845 GMT).

The companion satellite riding on the Delta II rocket was the Cosmic Hot
Interstellar Plasma Spectrometer, or CHIPSat. It will help astronomers study
the hot gas that lies between the stars.

Space fleet

Growth or shrinkage in ice sheets strongly influence sea levels and are
therefore critical in assessing climate change. But glaciologists do not
have the precise data they need to determine in which direction the massive
ice sheets in Greenland and Antarctica are really moving - or how they might
change as the Earth warms.

In Antarctica for example, scientists know the West Antarctic Ice Sheet is
smaller now than it was at the end of the last Ice Age but recently
collected data suggest this retreat may have slowed or even reversed in more
recent times.

Ice 'thickens' in West Antarctica

ICESat is designed to provide some definitive answers.

It carries just the one instrument: the Geoscience Laser Altimeter System
(Glas), which is the first space laser altimeter used to detect ice sheet
mass balance.

ICESat is one of a fleet of new Earth observation satellites that aim to
unravel some of the uncertainties associated with climate change.

The twin Gravity Recovery and Climate Experiment (Grace) spacecraft are
already in orbit and just coming online. They will measure gravity
variations across the Earth's surface - brought about primarily by shifts in
the distribution of ocean waters.

And Aqua, also launched last year, is collecting data on rainfall, snow,
sea-ice, temperature, humidity, vegetation, soil moisture and clouds.

Copyright 2003, BBC

============================
* LETTERS TO THE MODERATOR *
============================

(7) WAS THE K-T EVENT A ONE-OFF?

>From Hermann Burchard <burchar@math.okstate.edu>

Dear Benny,

Peter Ward has contributed much to our knowledge of how the great mass
extinctions have proceeded. In May of 2001, his group at U. of Washington,
Seattle, reported a very brief 50 Ka duration for the Tr-J extinction of 80%
of all living species at about 200 Ma. This was based on counting
radiolarians and measuring organic carbon burial, working in the Queen
Charlotte Islands, British Columbia (Science May 11 2001:  1148-1151). The
paper makes the point that three prominent extinctions, P-Tr, Tr-J, and C-T,
are all similar in the carbon excursion and its correlation with extinction
numbers.

Peter's statement (http://www.msnbc.com/news/750150.asp?0si=-) on the
UNIQUENESS of K-T impact, which implies that there is no evidence for any
other mass extinction linked to a large impact,
must be considered as bizarre and is simply wrong on all kinds of evidence
that has accumulated.

The fact that the Universe is a shooting gallery with Target Earth being hit
at random intervals that obey a scientifically known or at least knowable
probability law was first recognized by Ernst J. Öpik at Armagh Observatory.
These are positive probabilities large enough for at least
one global killer event being expected once about every 100 Ma. It would be
an extraordinary coincidence if Peter Ward is correct that it happened only
once, at the 65 Ma K-T catastrophe.

Earth's moon, Luna, is of course pockmarked with craters. Amazingly,
uncertainty over their meteoric impact origin lasted until the "first Apollo
landings in 1969.. [which returned rocks with] ..telltale signs of shock
metamorphism.. inarguable evidence that impacts were responsible for the
craters" (Duncan Steele, "Target Earth"). From the early days of space
probes sending close-ups of planet Mercury and the moons of Jupiter
astronomers were stunned with their uniformly dense, Luna-like cratering.
Tectonics on non-gaseous planets Mars, Earth and Venus, have erased many of
the craters. The 1994 Jupiter impacts of comet S-L-9 left long-lasting scars
in the planet's atmosphere.

Perhaps we are to believe major impacts happened alright on Earth but life
was left unscathed?  There are quite a few craters on our planet large
enough to rule that out. Surely the Sudbury impact must have been a killer
1850 Ma in the Proterozoic. Earlier in the Archaean, >2500 Ma, a
rich record of impact strata was formed (Andrew Glikson, CCNet Dec 6 2002).
A plethora of more recent impact ejecta layers have been reported recently
with the classical signatures established by Eugene Shoemaker, e.g.:  "A
Late Triassic Impact Ejecta Layer in Southwestern Britain."  Walkden, G.,
Parker, J., Kelley, S. (2002), Science 298, 2185-2188.

Also last year, Gerta Keller established that multiple impacts occurred at
K-T, 65 Ma (CCNet Nov 19 2002). In particular, the Chicxulub impactor, a
comet according to Gene Shoemaker on BBC, was not the main extinction event,
apparently a triple impact occurred at intervals 300 Ka or greater. This
little-noted discovery alone makes nonsense of K-T uniqueness.

The recent work by Olsen, Kent et al on the Newark Series seems proof enough
of an impact at the Tr-J extinction event, as it left an impact signature in
the form of a slight spike in Iridium.  ("Ascent of Dinosaurs Linked to an
Iridium Anomaly at the Triassic-Jurassic Boundary." P. E.
Olsen, D. V. Kent, H.-D. Sues, C. Koeberl, H. Huber, A. Montanari, E. C.
Rainforth, S. J. Fowell, M. J. Szajna, and B. W. Hartline, Science 296, May
17 2002, 1305.) This is the event that left the famous Palisade basalt rocks
along the Hudson River in N.Y. City.

People ask: Where is the crater? Well, it's a pretty familiar sight: The
North Atlantic Ocean!  Major impacts leave, beside neat circular craters,
several other kinds of signatures:

1) Hotspots, in the case of Tr-J this is presumably at the Azores.

2) Rifts, as the Tr-J impact actually split the continents when the N
Atlantic first opened up.

Prior to this, the continents of N America, S. America, Africa, and Europe
where all connected (even earlier we had an Iapetus Ocean of which Loch Ness
is a remnant; I hope I got that right).

3) LIPs, Large Igneous Provinces: This massive killer impact that wiped out
80% of all life on Earth produced a supervolcano erupting the CAMP, Central
Atlantic Magmatic Province, on all four of those continents. This is merely
one of many LIPs, all presumably related to ET impacts.

According to COSMIC LOG's account, Peter Ward suspects these LIPs were
responsible for extinctions, but apparently has ruled out any connection
with ET impacts. This theory now can be dismissed on the strength of the
above quoted work of Olsen, Kent, et al.

Now, one might wish to argue against this, as Ward does, which is the
central theme of the book "Major Impacts and Plate Tectonics: A Model for
the Phanerzoic Evolution of the Earth's Lithosphere" (by Neville J. Price,
University College, London), a technically formidable work that I have not
yet studied in detail. However, the mechanisms of impact causation of an LIP
are fairly evident and well stablished in volcanology, where the importance
of explosive gas release from depressurizing magma is understood to be one
of the main ways volcanoes erupt. Steve Sparks
(Bristol University) did work on this, he calls it "magmatic frothing", a
very descriptive name.  Beneath impact craters we have depressurized mantle,
as crustal rocks to a depth of up to one tenth of the crater diameter have
been excavated and removed by the impact explosion, reducing the overburden
on the highly viscous magma which rises slowly from the mantle.  The upper
mantle strata under the crater gradually depressurize. As the tectonic plate
slides over the spot, the crustal crater is cut off from the depressurized
magma, which moves beneath the adjacent crust.  A mound is formed by the
rising, highly viscous magma, which eventually will suffer eruptions as the
external pressure is sufficiently reduced on the dissolved gases to drop
below the vapor pressure. (See Boris A Ivanov & H. Jay Melosh, 2002,
"Impacts do NOT initiate volcanic eruptions") There, it is falsely assumed
that to produce volcanism mantle temperatures under the crater must be
raised above the solidus, ignoring magmatic frothing.
  http://www.lpl.arizona.edu/lplc/abstract_volume/ivanov.pdf

A hotspot has been born. In a typical situation a 100 km crater would be
excavated to a depth of 10 km, and then covered over in 2.5 Ma. In the mean
time there may be several eruptions producing an LIP. After the hotspot is
covered over, stepped erruptions occur and form the familiar chain of
mounts, as in the Hawaiian chain. Thus we get:

4) Hotspot Tracks, as the fourth non-crater signature of an impact.

Eventually, geologists will agree on the thesis that hotspot tracks (of
which there are lots) are indeed impact signatures, abandoning theories
about "mantle plumes" with their origin in heating at the D'' layer at the
CMB, as a part of large scale mantle convection. These ad-hoc theories
(insufficiently founded on observational data, often adducing modelling to
supplement ambiguous seismic tomography made difficult by nearly uniform
wave speeds in the mantle and overstating heating at the CMB) were proposed
prominently by W. Jason Morgan, Princeton, at a time (1971) when few people
beside Gene Shoemaker had begun to look into ET impacts.

In the case of the Yellowstone hotspot, for the sequence of these
supervolcano eruptions at intervals > several 100 Ka (see Barbara P. Nash
and Michael E. Perkins, Explosive silicic volcanism of the Yellowstone
hotspot: The ash-fall tuff record. Geological Society of America Bulletin,
v. 114, (2002)  367-381). The hotspot probably began 17.5 Ma ago with a
crater remnant yet to be found. From the known plate motion, it should be in
N Central Nevada.  But due to the presence of active gold mines there it may
be difficult to get good geological maps.

In several of my CCNet notes, I reported what in my lay-man like ways I
considered to be perfectly good evidence relative to P-Tr:  Briefly, the
"crater" was actually obliterated by the
impact volcanism as has been widely suggested it would be, but still its
location can hardly be in doubt, and naturally it's huge:  The 2,000 km West
Siberian Plane, a terrestrial mare.  The amount of basalt in it has been
estimated as more than the entire Siberian Traps.  This is fairly old
knowledge.  Also the date is the right one:  250 Ma, as was shown recently
from old drill cores.  It has at least one sister site, the adjacent South
Kara Sea, and possibly another one at Meishan.

The two impacts at the Siberian sites rejuvenated and in fact exhumed the
previoulsy levelled Ural Mountains, reheated at 250 Ma, a spectacular high
pressure eclogite band formed at depths of 10 km or so, re-excavated I
suspect by the impact thrust from the East, running the entire length of the
mountain chain and the double S-outline (see work by fellow Oklahoman Mary
Leech, Stanford, for fundamental work in her thesis on the geology of the
Urals).  The cross section of the Ural Mountain Chain, even at this vast
scale, shows the unmistakable, hallmark signature of a crater wall: The
Western slope away from the impact crater is bedded sedimentary Permian
rock, the city of Perm is located here, no volcanics.  The Eastern slope is
an abrupt descent, with basalt layers from the impact eruption interspersed
among the sedimentary rocks, to the magmatic plane (covered over by 250 Ma
worth of sediments).

There was only ocean where Siberia is now.  Until late Jurassic times, an
Okhotsk-Mongolian Ocean separated the emerging Siberian continent from the
main continent of Asia.  The entire present-day landmass of Siberia is
essentially co-extensive with the Siberian basalts (covered by later
sediment), a hot-spot track formed when the the proto-Siberian tectonic
plate slipped Westward, beginning with the massive outpouring of the
Putorana Mountains East of Norilsk located on the Eastern edge of the W
Siberian Basin (with its mines that have been described as similar to
Sudbury).  The track is not hard to trace all the way to Kilauea.  As the
cusp in the Kuril-Aleut trench indicates there is continuity here with at
most some subduction (and some lateral offset perhaps).  The supervolcano
outpourings buried those wonderful avian dinosaur fossils in N China (as the
SE Nebraska ashfall was sent there from the Bruneau-Jarbidge supervolcano in
the Owyhee Mountains in SW Idaho, a distance of 1,000 miles).

At the sight of Kilauea (even on photos) we can only marvel:  If this much
is left from the impact hotspot after 250 Ma, the presumptive comet coming
down in at least three pieces as it broke up from tidal effects of Earth's
gravity, it must have been some whopper, on the order of 100 km, an
Edgeworth-Kuiper belt object slung into the inner solar system by planet
Jupiter's gravity, having our name on it, or that of the species that would
live here if it didn't run into our planet.

For myself, a mathematician, there is enough geometric proof here based on
physical juxtaposition to satisfy me personally. The linkage from the West
Siberian Basin to the Hawaiian volcanoes may seem farfetched, but there is
proximity and step-by-step connectivity, as in the old ditty: "The Head
Bone's Connected to the Neck Bone.."  As we all know, ultimately the head
bone is connected to the toe bone. But unfortunately, Peter Ward's procedure
seems to be what I like to call "proof by ignoring the evidence".

Best regards,
 Hermann

=============
(8) RETURN TO THE MOON

>From Richard Taylor <richard.taylor3@virgin.net>

Dear Benny,

David Whitehouse raises a number of very important points when he says:

"We do not know how much a manned Mars mission would cost, but we do know it
would be very, very expensive. For many years cost estimates were literally
plucked out of the air. Hundreds of billions of dollars were mentioned with
little real rationale behind them. But even with our best technology (we
didn't have CAD and electronics in the Apollo days) and our imagination
(inflatable spacecraft, in-situ production of resources, non-chemical
propulsion etc) it will undoubtedly have an astronomical cost." 

And then continues: " What about going back to the Moon first? "

The fact is that if mankind is going to conduct manned space exploration of
the solar system, to establish scientific bases or permanent colonies, or
more locally to put large structures like orbiting space hotels or O'Neill
Habitats in orbit around the home planet, economics indicates that all this
must be done from the Moon.

Indeed the Moon is the keystone - the hub - of any future exploitation of
space. Although Bob Zubrin's Mars Direct concept does offer cost advantages
over an Earth/Mars Apollo style mission the outcome would probably not
extend beyond a small number of visits before political considerations of
cost shut the manned missions to Mars programme down. It would be as David
says another case of been there - done that.

Developing the Moon is a different matter - it is close by, has some 90% of
the materials we need for its initial robot and telechiric development, many
of the power generating requirements and the supply of certain essential
components for life support can built up by robots from in situ materials -
oxygen for example. Most if not quite the fundamental development work
necessary for humans to live and survive on the Moon can be prepared without
requiring the presence of humans in the initial stages. This makes the whole
task much more affordable. Eventually the only things operated from, and
perhaps built on Earth, would be man carrying surface to LEO vehicles a la
Alan Bond's Skylon and David Ashford's Space Bus, and even these vehicles
might be made on the Moon which will be the provider of all other space
hardware other than small scientific research satellites which will probably
continue to be launched from Earth.

The problem I see is that governmental agencies are unlikely to provide the
drive or the stability to get a consistent programme or continuing effort to
get the job done. The very idea of doing any development work using human
astronauts carries such a high cost ticket that we can rule out any such
programme out unless a new cold war situation arises and another
demonstration of technical prowess is required. Robots on the other hand are
expendable, don't require life support and are far cheaper to operate in
consequence.

In the short term it may be possible to start to show commercial
possibilities in such things as competitive supply of the ISS and other LEO
activities D.F. Robertson has enunciated some interesting ideas as to how
this might be possible (see 'A Place to Trade in Space' Spaceflight, 43, pp.
456-458, 2001). Commercial returns from LEO & GEO are already vast when we
think of communications, navigation, Earth meteorological, environment and
resources monitoring, the problem is that governments do not for some reason
see that these activities were, are, made possible through the exploitation
of space. Present attitudes to venturing further are rather as if stone age
man having invented the hide cover boat and the paddle had never wanted to
develop any other form of ship, leave alone aircraft or anything else.
Developing the Moon and exploring other remote places can not yet be seen as
having economic potential. But if 100 years ago, just after their first
powered flight,  the Wright brothers had said that within a little more
than half a century several hundred people a time would cross the widest
oceans at 500 miles an hour and the resulting profits and economic benefits
would be major contributors to the GNP of most nations, would any reasonable
person have believed them?

Hope the family are well.

Best wishes for 2003.

Richard Taylor

==========
(9) TUNGUSKA & THE 1953 LUNAR FLASH

>From Jens Kieffer-Olsen <dstdba@post4.tele.dk>

Dear Andy Smith

It's good to read your optimistic and positive report on 2002 Progress (
CCNet 2/2003 -  9 January 2003 ). On the issue 'Next Tunguska Class Impact
Risk', however, I feel your skepticism further founded by another 2002 article.

You wrote:

> We welcomed the attention recently given to trying to refine
> estimates of the risk of the next major NEO hit and we urged
> caution, in reducing the risk estimate (from about 1 in 100 years
> to about 1 in 1,000 years)....based on recently reported fireball
> data.

Not long after the fireball item we read an item in CCNet 144/2002 - 16
December 2002, which points in the opposite direction:

> Identification of the lunar flash of 1953 with a fresh crater on the
> Moon's surface
> L. Johnson (Pomona College), B. J. Buratti (Pomona College and JPL)
>
> The 1953 photograph of a flash on the Moon by an amateur astronomer
> (Stuart, 1956) is the only unambiguous record of the rare crash of
> an asteroid-sized body onto the lunar surface. We estimate that this
> event would have made a 1-2 km sized crater, and that the radius of
> the impacting body was about 170 m. Such an event would cause
> destruction of a large metropolitan-sized area if it occurred on
> Earth.

Considering the modest size of the Moon it alters impact frequency little to
count our double planet as one.  All of a sudden we may now have TWO major
NEO events hitting us in just one century, Tunguska in 1908 and Stuart's
Moon impact in 1953.  Not exactly a reassurance that it happens once a
millennium on average!

Yours sincerely
Jens Kieffer-Olsen, M.Sc. (Elec. Eng.)
Slagelse, Denmark

============
(10) RE: NEXT TUNGUSKA CLASS RISK

>From Andy Smith <astrosafe22000@yahoo.com>

Hi and thanks for your note. This is a great issue to discuss on the CCNet.
The recent lunar impact, which you cited, gives us another data-base to
include, on the side of being careful about reducing the risk of the next
hit.

In my last input to Benny and the Net, I cited the post-Cambrian extinction
record. It fits well on our exponential step-scale of NEO sizes and impact
intervals (with each step, we double the NEO width and increase the interval
between hits by about an order of magnitude).

If we put the K-T (or larger) impact on the scale (about one in a hundred
million years), we find the Tunguska interval at slightly less than a
century. We have found the same thing in all of the data bases (lunar
craters, the earth meteorite record, etc.) and this makes us feel
comfortable questioning the conclusion reached from a few years of fireball
data. The fireball data is valuable and we use it....but it is not an
adequate challenge to the older and much longer-based sources.

This is one of the most important technical issues we can discuss on the Net
and it is great to see the kind of dialogue we are having. It is also good
to hear from you and we wish you a happy and prosperous New Year.

Cheers.

Andy

============
(11) AND FINALLY: "WE DON'T WANT ANY JUNK IMPACT CRATERS IN OUR
NEIGHBORHOOD"

>From Ron Baalke <baalke@zagami.jpl.nasa.gov>

http://www.sltrib.com/2003/Jan/01102003/utah/18930.asp

Plan to Mimic Meteorites With Bowling Balls Lands With Thud at BLM

BY GLEN WARCHOL
THE SALT LAKE TRIBUNE
January 10, 2003

A group of amateur scientists planning to bombard Utah's salt flats with
bowling balls to simulate meteorite impacts has caught the attention of the
Bureau of Land Management.

Bill White, a BLM research scientist, called The Salt Lake Tribune, saying
officials were startled to see a story Wednesday about amateur astronomers
contemplating dropping objects, possibly bowling balls, from an airplane to
help identify meteorite strikes in the salt beds.

"We are not sure we want impact craters in the salt surface," White said.
"There is a concern this will impact the resource itself. We have enough
junk out there already."

Full story here:
http://www.sltrib.com/2003/Jan/01102003/utah/18930.asp


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