PLEASE NOTE:
*
CCNet, 14 December 1999
------------------------
SONG OF THE DAY
Penny Lane (Lennon/McCartney)
In Penny Lane there is a barber showing
photographs
Of every head he's had the pleasure to
know.
And all the people that come and go
Stop and say hello.
On the corner is a banker with a
motorcar,
The little children laugh at him behind
his back.
And the banker never wears a mack
In the pouring rain, very strange.
Penny Lane is in my ears and in my eyes.
There beneath the blue suburban skies
I sit, and meanwhile back
In Penny Lane there is a fireman with an
hourglass
And in his pocket is a portrait of the
Queen.
He likes to keep his fire engine clean,
It's a clean machine.
Penny Lane is in my ears and in my eyes.
A four of fish and finger pies
In summer, meanwhile back
Behind the shelter in the middle of a
roundabout
The pretty nurse is selling poppies from
a tray
And tho' she feels as if she's in a play
She is anyway.
In Penny Lane the barber shaves another
customer,
We see the banker sitting waiting for a
trim.
And then the fireman rushes in
From the pouring rain, very strange.
Penny Lane is in my ears and in my eyes.
There beneath the blue suburban skies
I sit, and meanwhile back.
Penny Lane is in my ears and in my eyes.
There beneath the blue suburban skies,
Penny Lane.
-------
On the occasion of Sir Paul McCartney's return
today to
the Cavern Club after 36 years. What is
predicted to be
the largest webcast to date takes place this
evening
when Sir Paul will perform live at the Cavern
Club here
in Liverpool - for the first time since the
Beatles
played there last in 1963. PC users will be
able to
follow the live broadcast at 8.00pm by logging
on to
the internet at www.msn.co.uk/cavern
Have fun with some great Merseybeat!
(1) GEMINID DROPPINGS IN AUSTRALIA?
Robert Clements <Robert.Clements@dva.gov.au>
(2) MELBOURNE WOMAN'S METEORITE CLOSE ENCOUNTER
Network TEN News Service, Tuesday, 14 December
1999
(3) ON THE VELOCITY OF METEORITE FALLS
Duncan Steel <D.I.Steel@salford.ac.uk>
(4) ROBOT WILL JOIN ANTARCTIC METEORITE SEARCH
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) PROSPECTING FOR OIL? LOOK IN AN ASTEROID CRATER
Michael Paine <mpaine@tpgi.com.au>
(6) SHIVA IMPACT CRATER - INDIA
Michael Paine <mpaine@tpgi.com.au>
(7) ANTARCTIC ICE-SHEET THINNED BY 200 M IN JUST 1000 YEARS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(8) ROCK ANALYSES MAY PAVE WAY FOR LASER TOOL'S FUTURE
USE IN SPACE
Andrew Yee <ayee@nova.astro.utoronto.ca>
=============
(1) GEMINID DROPPINGS IN AUSTRALIA?
From Robert Clements <Robert.Clements@dva.gov.au>
The following article will appear on tonight's (Tuesday 14
December
1999) Ten Network (Australia) news bulletin. I'll try & find
out
whether there is any real evidence to associate the strike with
the
Geminids; & by extension, Phaethon....
All the best,
Robert Clements <Robert.Clements@dva.gov.au>
-----
Network TEN News Service, Tuesday, 14 December 1999
Meteor spectacle in southern skies
Another meteorite spectacle, this time in Melbourne. A woman
witnessed
a rock come crashing through her bedroom window. The small
fragment
will be sent to Sydney for further testing.
http://www.ten.com.au/newsRedir.asp?NewsID=3743
Meteor spectacle in southern skies
Another meteorite spectacle, this time in Melbourne. A woman
witnessed
a rock come crashing through her bedroom window. The small
fragment
will be sent to Sydney for further testing.
But the fireballs visible in South Australian and Victorian skies
overnight may be just a curtain raiser for a meteorite shower
expected
on Wednesday.
National Space Centre director Ross Dowe says more than 70 people
have
phoned the centre's hotline to report seeing huge fireballs in
the sky
at about 9.30pm. He says reports have come from as far north as
the
Northern Territory border, down to the state's south.
Mr Dowe says the fireballs appear to be a meteor storm dropping
debris
into space. But he says the shower could be just a prelude to the
spectacular Geminid shower expected in Australian skies on
Wednesday.
===========
(2) MELBOURNE WOMAN'S METEORITE CLOSE ENCOUNTER
From Network TEN News Service, Tuesday, 14 December 1999
http://www.ten.com.au/webCh10/Admin/NewsSport/NewsSport/viewNewsSport.asp?NewsID=3743
A Melbourne woman is thanking her lucky stars after a close
encounter
with a meteorite which came crashing through her bedroom
window.
Kelly Johnson thought she was being shot at when a rock just the
size of a thumb nail came crashing through her window, missing
her by centimetres.
Kelly says her initial thought was that it was a shot gun or kids
throwing rocks. Because it landed with such force Kelly called in
the
professionals to analyse her mystery rock. She's just grateful it
wasn't
the size of the meteorite which landed in a northern NSW dam last
week.
That mystery object, believed to be the size of a cricket ball,
flattened
reed beds covering an area larger than a tennis court.
Geologists say meteorites re-enter the atmosphere at a speed of
10km/second - that's 500 times faster than a speeding bullet. And
at a
temperature of 2000 degrees Celsius, they can kill.
Ms Johnson's disappointed she can't keep her stratospheric
specimen.
The rock must be sent to Switzerland, which is the official home
of all
unexpected visitors from outer space. But there is one
consolation - it
will be named after her on the World Meteorite Registry.
Copyright 1999,
===========
(3) ON THE VELOCITY OF METEORITE FALLS
From Duncan Steel <D.I.Steel@salford.ac.uk>
At 36,000 kph = 10 km/sec, any mass possesses as the kinetic
energy
12 times the chemical energy of TNT. That is, one expects it to
explode
& evaporate on impact (sudden deceleration). Small objects
like this
I would not expect to be travelling at hypervelocity when they
reach the
ground: any mass surviving atmospheric entry of such a small size
would
have decelerated to free-fall speed by the time it reaches the
ground
(circa 200 kph but dependent upon mass/cross-sectional area
ratio, drag
parameters etc.). I would have guessed that the 'impactor' was
actually a
fairly dense lump (metal?) dropped off of a plane, with a size
around half
(or more) of the hole it produced. It hit the dam at 200-300 kph
and buried itself in the soft bottom. But that would not explain
the
'seismic' record (I would think that Gordon is correct as
suspecting
a sonic boom), hence I would stab at it having been space debris.
Sonic boom = final deceleration at an altitude of circa 5-10 km
having
entered the atmosphere at 7.5 km/sec.
Cheers,
Duncan
===========
(4) ROBOT WILL JOIN ANTARCTIC METEORITE SEARCH
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Case Western Reserve University
Cleveland, Ohio
For more information, contact:
Susan Griffith, 216-368-1004 or sbg4@po.cwru.edu.
12-10-99
Robot will join Antarctic meteorite search
Researchers from two adventuresome programs in planetary science
will
meet on an Antarctic ice field in January to test the
capabilities of a
Volkswagen-sized robot to find and track locations of meteorites.
Meteorite hunters from Antarctic Search for Meteorites (ANSMET),
a
National Science Foundation polar program, will join robotic
scientists
from Carnegie Mellon University's Robotic Institute. Ralph
Harvey, a
planetary geologist at Case Western Reserve University, directs
ANSMET's
exploration operations in Antarctica.
Nomad, a four-wheeled robot, was developed with support from
NASA's
Cross Enterprise Technology Development Program.
The principal investigator is William (Red) Whittaker, Carnegie
Mellon
University's Fredkin Research Professor of Robotics. Dimitrios
Apostolopoulos, a systems scientist at Carnegie Mellon, is the
project
manager.
The Robotic Institute developed Nomad for NASA to undertake
planetary
science research on Earth as an analog to exploring Mars or the
Moon.
ANSMET, which has collected more than 10,000 meteorites over the
past
23 years and makes specimens available to researchers around the
world,
will meet Nomad and its operators on the Elephant Moraine, a
meteorite
collection site on the east Antarctic plateau.
The robot will be transported by helicopter to the site
approximately 200
miles northwest of the United States' McMurdo Station on the
Antarctic
coast. It is a site where Nomad, using Global Positioning System
(GPS)
tracking to mark a meteorite's location, can pick up the
satellite signals
on the horizon above the equator.
The joint exploration will take place after ANSMET completes this
year's
search. Harvey left Cleveland November 17 for target searches at
Foggy
Bottom near the Beardmore Glacier, Goodwin Nanataks, and
MacAlpine
Hills approximately 600 miles south of Elephant Moraine. ANSMET
and
the Nomad teams will link up at McMurdo Station in mid-January
for the
joint expedition.
ANSMET surveyed Elephant Moraine 15 years ago, but used older
search
methods that did not recover all meteorites from the site. During
a short
visit to the site in 1996, Harvey says they found six meteorites
in 30
minutes, suggesting that this will be an ideal area for Nomad's
first
autonomous foray.
"Nomad will fill the stereotypical role of the robot
cleaning up after the
humans," explains Harvey. "Robots don't lose their
concentration and are
happy to do jobs that are repetitive and difficult, allowing
humans to do
something else that might be more exciting and profitable. This
is a great
opportunity for Nomad and ANSMET."
This field has yielded some past treasures, including more than
2,000
specimens on seven previous visits. One important specimen found
is
EET97001, the first meteorite determined to be of unambiguous
Martian
origin.
According to Harvey, the site gets its name for its resemblance
to the
features of a small elephant with an enormous tapering trunk. The
Nomad
and ANSMET researchers will search for meteorites in the area at
the
end of the trunk.
"If Nomad finds meteorites that we might not recover
otherwise, because
other sites have a higher priority, then this is a great boon.
Nomad will
be doing real work on behalf of ANSMET and the planetary
materials
community, rather than simply demonstrating some
technology," says
Harvey.
In preparation for this year's trip, Nomad made trips to Patriot
Hills'
blue ice field in Antarctica in 1997 and 1998 to learn to
maneuver in
Antarctica's fanciful weather and to distinguish Earth rocks from
extraterrestrial ones.
The Elephant Moraine will give Nomad varied experiences, from
fields
with few objects on the thousand-foot-thick ice sheet, to places
where
a 100,000 rocks have been pushed together by an encroaching
glacier.
Nomad can identify rocks with magnet sensors as well as optical
sensors.
It has been programmed to search for meteorites by size, texture,
and
color, and to learn as it goes.
"We're not at the point where John Henry takes on the steam
engine. This
is not about replacing humans with robots. Instead, it is a neat
exercise
where robotic technologies and autonomous robotic behavior act in
concert
with human skills and behavior," says Harvey.
===========
(5) PROSPECTING FOR OIL? LOOK IN AN ASTEROID CRATER
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny, here is my latest Rocks from Space article
Prospecting for oil? Look in an asteroid crater
By Michael Paine for explorezone.com
http://www.explorezone.com/columns/space/1999/december_oil.htm
Earth has suffered thousands of violent collisions with asteroids
and
comets over four billion years. The scars from these collisions
are
impact craters. But the Earth hides its wounds well -- less than
two
hundred impact craters have been discovered. Many are buried deep
below
the surface. They were only found by accident during geological
surveys
that were part of the massive, ongoing effort to find oil for an
energy-dependent world.
Now it seems that the link between impact craters and oil is not
accidental. Buried impact crater formations make excellent
underground
traps for oil, but these craters rarely seem to be above the
types of
rocks that are supposed to contain oil. New thinking changes all
that.
If Russian theories about the non-biological origin of much of
our oil
prove to be accurate, then there may be good reasons for oil
prospectors
to go searching for impact craters.
Where does oil come from?
"Rock oil originates as tiny bodies of animals buried in the
sediments
which, under the influence of increased temperature and pressure
acting
during an unimaginably long period of time transform into rock
oil" --
M.V. Lomonosov 1757AD.
Maybe it's time to change the textbooks.
For two centuries Lomonosov's simple and compelling theory on the
origin
of oil went unchallenged. It meant, of course, that the world
would run
out of oil once the rare sedimentary rocks that contained the
bodies of
animals were drained of oil. It also meant that so-called
basement
rocks, which had never been near the surface of the Earth, would
not
contain oil.
The Russians decided to try something different. In the 1950s,
perhaps
due to the pressures of the Cold War, they started to hunt for
oil
according to a new theory: that most oil occurred naturally, deep
within
the Earth's crust, and had nothing to do with rotting organisms.
That
hunt has been highly successful, and the former Soviet states
have many
commercial oil wells apparently producing from deep basement
rocks.
Tom Gold, Professor Emeritus of Astronomy at Cornell University,
supports the Russian idea. In his book "The Deep Hot
Biosphere," Gold
discusses the discovery of life deep within the Earth' s crust.
He
argues that most oil and gas could only have come from
non-biological
sources much deeper underground.
According to this theory, the natural traps formed by impact
formations
will be even more promising as places to look for oil because the
"source rocks" containing the oil are everywhere.
Liquid gold in the rubble of an impact crater
Wham! 65 million years ago a huge asteroid hit the Earth in a
shallow
sea off the coast of Mexico(See a map). A crater perhaps 150
miles or
more across was briefly formed in the seafloor and chunks of rock
were
scattered in mile-thick layers for hundreds of miles in all
directions.
Tsunami from the impact churned up more piles of broken rocks on
coastlines thousands of miles away.
Over time, layers of sediment covered the impact scars and they
lay
undisturbed for millions of years. Then, only several decades
ago,
prospectors started looking for oil in the region, unaware that
the
Chicxulub crater lay buried deep beneath them. They were very
successful, and commercial oil production began. But it was not
until
1990 that the signs of a crater were recognised. The rubble from
that
impact is now thought to be the source of most of Mexico's vast
oil
reserves. Geologists are beginning to see that impact crater
formations
make good traps for oil.
How it gets there
Oil from deep underground gradually works its way upward through
cracks
and fissures in rocks. Oil prospectors get excited if the
"reservoir
rocks" that contain the oil are covered by a contorted layer
of "cap
rocks" because this can confine oil in natural reservoirs.
An oil well
is usually drilled until it breaks through the cap rocks and
reaches the
oil-saturated reservoir rocks below.
The rubble from an impact often forms a porous rock known as
Breccia
that is full of cracks and fissures -- making it excellent for
extracting oil through a well. Domes, basins, deep cracks and
crumpled,
folded landforms are other typical features of an impact crater
that
make them promising for oil prospectors.
There are hundreds of thousands of oil wells in the United
States, but
only a dozen or so are known to be associated with impact
structures.
Like Chicxulub, none of the craters were discovered until after
commercial production of oil began. Geologist Richard
Donofrio of Oklahoma City points out that drilling an
impact structure is much more likely to be successful
than drilling other types of formations.
Deep under the layers of sedimentary rocks covering most of the
United
States there should be at least 20 undiscovered impact craters.
Canada's
geology is different and most craters are on or near the surface.
Donofrio therefore went through the exercise of randomly
superimposing
the distribution of known Canadian impact craters on a map of the
USA.
Using conservative assumptions he came up with an estimate of the
oil-producing potential of undiscovered impact craters in the
USA. His
conclusion is staggering: 50 billion barrels -- double the
current
proven U.S. reserves.
Geoscientist John Gorter from Perth, Western Australia has
studied the
petroleum potential of Australian impact structures. He also
believes
that impact craters make very promising sites for oil
exploration. The
most interesting, and speculative, of the Australian sites is the
Bedout
Structure some 200 miles off the coast of Broome. There are
tentative
signs that this was originally a crater 160 miles in diameter --
perhaps
bigger than Chicxulub. If it does turn out to be a large impact
crater,
there could be huge reserves of oil in the region.
The Bedout Structure could also be of interest to
palaeontologists --
its possible age of 250 million years corresponds with the great
mass
extinction at the end of the Permian period.
Tar-coated comets and oily asteroids
The idea that complex hydrocarbons (the main components of
petroleum
oil) are a natural part of the Earth's crust should come as no
surprise
to scientists who study comets and asteroids. Some of the
meteorites
that fall to Earth are rich in tar-like hydrocarbons. Comets such
as
Halley and Hale-Bopp are thought to have a skin of tar-like
material
covering a "dirty snowball" - like an ice cream dipped
in chocolate.
The early Earth was made of the same stuff as comets and
asteroids, so
the presence of hydrocarbons deep within the Earth is to be
expected. It
used to be thought that the fierce heat deep underground was
sufficient
to break up any hydrocarbon molecules. However, Russian
scientists have
demonstrated that the enormous pressures prevent this.
Even if the Earth did not manage to retain its original supply of
hydrocarbons it is likely that the rain of comets, space dust and
asteroids over billions of years would have kept the crust of the
Earth
topped up with the raw ingredients for oil.
Could there be too much oil?
Oil is best found near impact structures. Oil forms deep
underground
from non-biological processes. If these ideas prove correct then
Donifrio's estimates for the United States should apply to other
parts
of the world. For areas of similar size there are possibly 20
buried
impact craters with perhaps half having commercial oil reserves.
The
search for these elusive craters could be very rewarding.
It may turn out that there is too much oil for our own good. A
massive
increase in known oil reserves could lower oil prices and
drastically
devalue existing reserves. A longer-term problem is that an
unchecked
increase in oil consumption could place untenable strain on the
global
environment. Already human activities in our oil-dependent
society have
led to alarming species extinction rates. An oil glut could
accelerate
this problem.
It would be ironic if the Chicxulub impact event turned out to be
a time
bomb that was not only associated with the extinction of the
dinosaurs,
and many other species at the end of the Cretaceous Period, but
also
with another mass extinction resulting from human activities some
65
millions years later.
Copyright Explorezone 1999
============
(6) SHIVA IMPACT CRATER - INDIA
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
While researching the oil and impact crater article for
Explorezone
I came across the following news item at
http://www.edge.ou.edu/news/news.htm#shiva
regards
Michael Paine
EDGE Investigating Shiva Crater in India (1/30/99)
by Kathy Sokolic, EDGE
Cores from basement rocks of India's offshore Bombay High field
are
being studied to determine if they were affected by meteorite
impact.
Dr. Richard R. Donofrio, EDGE Research Associate, obtained the
Precambrian samples from India's Institute of Petroleum
Exploration in
Dehra Dun following an inquiry by Dr. Sankar Chatterjee at Texas
Tech
University. Dr. Chatterjee, in studying mass extinction at the KT
boundary, mapped an apparent buried oblate feature 600 km long,
450 km
wide and 12 km deep carved through Deccan Traps and into
underlying
Precambrian granite. If of impact origin, the "Shiva
Crater" would be
the largest impact feature of Phanerozic age exceeding the
Chicxulub
crater off Mexico's Yucatan Peninsula (both craters may be part
of the
same event).
Initial petrographic studies by Dr. David London of the
University of
Oklahoma's School of Geology and Geophysics, detected
pseudotachylites
and microcrystalline spherulites typical of devitrified glass,
possibly
of impact origin. Pseudotachylites, an injection breccia
containing
shocked material emplaced in fractures created during an impact
event,
have been found in some astroblemes. Analyses at the USGS Menlo
Park,
conferred with the findings of Dr. London. Microprobe studies are
currently underway, and additional samples have also been sent to
Dr.
Paul Renne at Berkley's Geochronology Center for age dating. In
addition
to its extinction significance the Shiva Crater also holds
India's
largest oil field, Bombay High. This field has reserves exceeding
1.4
billion boe (barrels of oil equivalent) and produces from Miocene
limestones overlying the apparent central uplift of the crater.
Dr.
Donofrio notes that an impact origin for Shiva can determine oil
and gas
drilling locations. Refer to his paper published in the May 11,
1998
issue of the Oil and Gas Journal for a discussion of impact
structures
as hydrocarbon traps (see article link in EDGE Contents). For
additional
information about the Shiva Crater and related extinction events,
contact Dr. Chatterjee at mxsan@ttacs.ttu.edu.
============
(7) ANTARCTIC ICE-SHEET THINNED BY 200 M IN JUST 1000 YEARS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
University of Washington
FROM: Vince Stricherz, 206-543-2580, vinces@u.washington.edu
FOR IMMEDIATE RELEASE: Dec. 13, 1999
Radar mapping could yield new clues to past Antarctic ice stream
activity
SAN FRANCISCO -- A new technique using ice-penetrating
radar is allowing scientists for the first time to reveal
long-ago changes in West Antarctic ice streams, rivers of
ice believed to be linked to the stability of the massive
West Antarctic Ice Sheet. Disintegration of the ice sheet
could gradually increase global sea levels 15 to 20 feet.
In the past, changes in the ice streams were determined
from observing surface features, which only provided
information for a few hundred years. Evidence of changes
from a more distant past was carried away in the streams'
relatively fast flow. Ice streams move at 0.5 to 1
kilometer a year, while the rest of the ice in the sheet
moves a few meters or less per year.
Now, radar measurements of internal layers in the islands
of slow-moving ice between the streams allow scientists to
look at ice stream changes much farther back in time, said
Nadine Nereson, a geophysics research associate at the
University of Washington who worked with other scientists
to develop the technique.
The five primary ice streams within the 360,000-square-mile
West Antarctic Ice Sheet are labeled A through E, and the
three most prominent ridges are called Siple Dome (between
streams C and D) and Ridges BC and DE (named for the streams
between which they lie).
The shape of layers beneath Siple Dome indicates its high
point has been moving to the north. Other evidence suggests
the movement likely was caused by thinning of Ice Stream C,
at the southern edge of Siple Dome, before it stopped
flowing rapidly about 150 years ago. Radar data from Siple
Dome and ridges BC and DE in 1998 have enabled Nereson and
her colleagues to analyze the pattern of change in the
thickness of the ice stream system all along the Siple
Coast during the past several thousand years.
"The most exciting finding is that Ice Stream B may have
thinned by nearly 200 meters relative to Ice Stream C in
the 1,000 years," she said.
Nereson presented the findings during a news conference at
the fall meeting of the American Geophysical Union in San
Francisco today (Dec. 13). She and Charles Raymond, a UW
geophysics professor and principal investigator for the
project, found evidence that the divide position on the
ridge between ice streams B and C is the least stable of
all the ridges, suggesting significant changes in the ice
streams that border the ridge.
The technique of using radar to map the annual layers of
glacial ice was described earlier this year in the journal
Nature by UW geophysicist Edwin Waddington and colleagues
from the British Antarctic Survey. Their radar images
showed an arch in the layers beneath an ice divide. They
called such arches "Raymond Bumps" because Nereson's
co-author first postulated their existence in 1983. He
showed that ice deep under an ice divide should be very
hard and slow to flow, so the upper layers would tend to
drape themselves over it.
The new technique looks at how an ice divide is affected by
the changing depth of nearby ice streams. Radar
measurements made at Siple Dome in 1994 and 1996 showed a
significant Raymond bump, indicating the ice streams at its
boundaries are relatively stable, Nereson said.
Preliminary evidence from data gathered in 1998 indicates
Ridge BC has almost no Raymond bump, indicating that
streams B and C fluctuated greatly causing the divide to
move frequently. The data shows Ridge DE showed a slight
Raymond bump, suggesting slightly more stability. It is not
yet certain, however, whether the evidence from the other
two ridges can be interpreted as clearly as that from
Siple Dome, Nereson said.
The work, funded by the National Science Foundation, could
help determine whether the West Antarctic Ice Sheet is
disintegrating, as some have suggested, or is instead
becoming more stable.
Evidence that a natural cycle has thinned the ice sheet for
thousands of years and could bring its complete demise
about 7,000 years from now was presented recently in the
journal Science by a team led by UW geophysicist Howard
Conway.
###
For more information, contact Nereson at (206) 685-2887 or
nadine@geophys.washington.edu.
During the AGU meeting,
reporters can leave a message for her at the Renaissance
Parc 55 Hotel, (800) 650-7272 or (415) 392-8000.
===========
(8) ROCK ANALYSES MAY PAVE WAY FOR LASER TOOL'S FUTURE
USE IN SPACE
From Andrew Yee <ayee@nova.astro.utoronto.ca>
On Mon, 13 Dec 1999 16:35:55 -0500 Andrew Yee
<ayee@nova.astro.utoronto.ca>
wrote:
Los Alamos National Laboratory
Los Alamos, New Mexico
CONTACT: Ternel Martinez, 505-665-7778, tmart@lanl.gov
ROCK ANALYSES MAY PAVE WAY FOR LASER TOOL'S FUTURE USE IN SPACE
SAN FRANCISCO, Dec. 13, 1999 -- Analyses performed on a sliver of
terrestrial rock by the Department of Energy's Los Alamos
National
Laboratory may one day help researchers better understand the
makeup
of large extraterrestrial bodies such as Mars, comets and
asteroids.
Using Los Alamos-developed laser-induced breakdown spectroscopy,
the
researchers demonstrated they can account for weather-induced
surfaces on terrestrial rocks and identify the true, pristine
elemental compositions beneath.
The researchers explained their results today during the fall
meeting
of the American Geophysical Union in San Francisco. The work was
sponsored by NASA's Mars Instrument Development Program, now in
its
second year.
"It's very likely that Mars has some kind of weathering
process on
its surface, so we need to account for that in our future
analyses of
rocks and other samples from Mars," said Roger Wiens of Los
Alamos'
Space and Atmospheric Sciences Group. "Prior analyses of
Mars by
instruments on NASA's Viking and Pathfinder didn't take
weathering
conditions into account."
Los Alamos has been developing the LIBS technology since 1981. A
laser strikes samples of soil, air or water, evaporating the
sample
to form a hot microplasma and exciting the atoms to emit light.
LIBS
is based on the fact that all elements have unique spectral
signatures. By analyzing the spectra of the emitted light, LIBS
can
determine the sample's composition within minutes, even at
concentrations as low as two parts per million.
LIBS is more sensitive than other elemental analytical tools such
as
X-ray fluorescence and alpha proton X-ray spectroscopy. In
addition,
LIBS does not need to make direct contact with the sample; the
laser
can strike it from as far away as 22 yards. The technology has
won
three prestigious R&D 100 awards from R&D magazine over
the years and
has been commercialized for various applications.
In their recent studies, Los Alamos researchers used LIBS to
determine the composition of a rock sample from California's
Mojave
Desert. The rock's surface had a thick mineral varnish deposited
on
it by the desert's natural weather environment.
"Desert varnish can be up to half a millimeter thick. It
contains
manganese and clay minerals, which did not come from the rock.
This
means the varnish had to have been deposited on the rock through
some
kind of atmospheric phenomenon," Wiens said.
The researchers took the sample, which weighed less than 100
grams,
and broke it into several pieces. The places where the samples
were
broken contained no varnish. The researchers then illuminated the
samples' varnished and unvarnished areas with the laser from
about 10
feet away.
"Our results showed that LIBS 'bored through' the varnished
areas and
obtained the same elemental composition measurements as the
unvarnished areas," said Wiens.
The researchers are building a prototype rover-based LIBS
instrument
for field tests in the Mojave Desert scheduled for May. Wiens and
his
colleagues also are hoping to adapt LIBS for landing crafts to
perform
remote elemental analyses of comets and asteroids.
The Los Alamos research team consists of project leader David
Cremers
and colleague Monty Ferris of the American Chemical Diagnostics
and
Instrumentation Group; Wiens and Space and Atmospheric Sciences
Group colleague Jane Nordholt; Jim Blacic of the Geoengineering
Group;
and Nathan Miller of the Science and Technology Base Programs
Office.
Horton Newsom of the geology department at the University of New
Mexico also was a co-author on this work.
Los Alamos National Laboratory is operated by the University of
California for the U.S. Department of Energy.
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LETTERS TO THE MODERATOR, 14 December 1999
------------------------------------------
MORE LESSONS FROM THE MARS MISSON FAILURES
From Oliver Morton <abq72@dial.pipex.com>
Benny
Richard Taylor's comments on Mars exploration contain a great
deal of
wisdom. What follows is largely by way of an expansion on some of
them
from someone who just speant a very frustrating week in Pasadena.
As it applies to Mars, fasterbettercheaper has fallen between two
stools. The overall program is long range and broad-based; but it
consists of a set of individual missions that are quick and
focussed.
These missions depend on each other technically (MCO and MGS
would have
provided comms support to MPL; the 01 lander was originally
envisioned
as having no direct to earth link at all). They do not depend on
each
other scientifically. There are no plans to re-fly MCO; I would
be
shocked to see a polar lander now before 07 or 09. And though
that is
sad, it doesn't really affect the science goals of the 03-08
sample
return campaign at all. The individual missions, in short, do not
really add up to a scientific programme. They are an ongoing tech
development effort each part of which has been given an
independent
scientific rationale. This is because, in the post-Apollo era,
each
planetary mission has been expected to bring back unique,
important
planetary data. When each mission was conceived as a stand-alone
entity
that made sense. If they are conceived as an open ended
exploration of
a particular planet, though, expecting science return from every
launch
just confuses things.
If a sustained Martian exploration campaign is the right thing to
do,
then you have to get a robust infrastructure built first. To my
mind,
that means a multi-satellite navcom constellation in situ first,
one
that allows communications through two separate duplex channels
to any
point on the surface (I'd want six in orbit and two on-orbit
spares,
but I'd settle for less). The science orbiters are simply not an
adequate alternative to a robust system designed for
communications in
the first place. Once that system is up, then all future missions
will
know what there basic communications requirement will be, and the
Mars-surface to Earth-surface communications traffic will become
reliable and highly redundant (multiple transmission bands,
multiple
spacecraft). Since the navcom orbiters would not be scientific
missions
or technologically at the edge of the envelope, they could be
contracted out to industry reasonably easily, and QoS guarantees
could
be required. They don't have to be big or complex - they just
have to
get there and to work.
After that, develop a new scout-class Mars spacecraft. I'm
thinking of
a balloon-carried standardised camera/radar sounder/magnetometer
package that could be sent to Mars before every lander, launched
with a
separate, low-cost launcher. The idea would be to arrive at the
target
ellipse that the lander is headed for at least six weeks before
its
arrival and characterise the surface there in detail. There is as
yet
no dataset that comes close to characterising the Martian surface
at
the scale relevant to landers (30cm resolution would be nice),
nor will
any future mission currently in development provide one.
It is entirely plausible that it was terrain, not design, that
killed
MPL (Though it is because of poor design that we don't know for
sure).
Workable very-high-detail maps of the terrain created from the
scout's
descent imager and subsequent early flight operations would allow
a dud
landing site to be rejected for reasons of slope, rock abundance
or
whatever. It would also allow surface ops - eg rover traverses --
at a
good landing site to be planned in advance, thus increasing their
efficacy. After its primary landing-site-qualification mission
was
over, the balloon could then roam free either for a day (if a
montgolfier, which would be cheapest) or more (if
superpressurised, or
some kind of hybrid). Throughout its life it could be tracked and
communicated with by the navcom constellation above. These
production-line-produced scouts could make the overall programme
more
robust and also deliver a great deal of useful if untargeted
scientific
data at relatively low marginal cost.
If a balloon system is too expensive, some of the same goals
could be
made with a series of Ranger-like impactors taking pictures all
the way
down to the site, as long as there was communications capacity
enough
at Mars to get imagery and possibly radar sounding data from
them.
Another innovation required is competition. At the moment, all US
Mars
missions are JPL/Lockmart productions. So because of technical
and
managerial commonalities between all the missions the MPL failure
puts
the whole programme in doubt. The answer to this problem is to
allow
competition within the programme. Split the launch windows
between the
current team and a competitor, such as Johns Hopkins APL or
Ames/Ball.
A slower tempo would help JPL; so would the competition. (Brian
Muirhead at JPL has spoken about the fact that if you want to get
rid
of one aspect of fasterbettercheaper, then you should get rid of
faster, keeping worker-years constant but stretching the total
development cycle. It allows you to use a smaller team, all
members of
which work on more separate systems.)
Another technical possibility is rethinking the reliance on solar
power. Though the Viking missions carried plutonium-powered
radio-thermal generators (RTGs), today's NASA operates a
no-nukes-on-Mars policy. Solar panels are good politics (and that
is
not meant as a sneer; without good politics there is no space
programme) but they also present problems. They are bulky. They
have to
be deployed, which can go wrong. They get covered with dust,
limiting
mission lifetime. At the poles they have to be oriented in such a
way
as to catch the sun even when low on the horizon. Even in orbit
there
are issues; the off-centre solar panel for MCO was one of the
reasons
why the team had to keep doing correction burns while the
spacecraft
was in cruise, thus pushing it off course in ways they didn't
understand. A solar-panel problem made MGS's aerobraking phase
much
longer than it would otherwise have been. As far as I can
remember, no
US planetary spacecraft has ever failed because of problems with
plutonium RTGs.
Batteries are even worse than solar cells. The lifetime and radio
power
of the Deep Space 2 microprobes were very limited because of
their
batteries (which were hard put to function at all in the extreme
cold
of the south polar region). If they had had RTGs they would have
been
able to transmit with greater power and for longer periods, which
might
have allowed MGS to pick up their signals even if, as has been
suggested, the microprobes penetrated farther into the subsoil
that
intended. Also, if the penetrator design - which is quite cheap
and may
well be basically sound -- is to be used for subsequent missions,
such
as weather surveys or seismic surveys, a lifetime measurable in
years,
rather than days, would be a sine-qua-non. That means RTGs.
Nuclear power is obviously an emotive issue - and a time when
NASA is
making a lot of mistakes is not a great time to be asking it to
launch
more plutonium. (Imagine if the Cassini flyby had happened
*after* the
current spate of failures rather than before - would the concern
not
have been far more vocal and more plausible?) But nuclear power
does,
it appears, simplify the engineering and increase the robustness.
If it
can be launched in assuredly fail-safe containers, it should be
re-examined.
I could doubtless go on longer, but that seems enough to be going
on
with.
Oliver
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