PLEASE NOTE:
*
CCNet 121/2000 - 23 November 2000
---------------------------------
"NASA has not 'dropped the ball'; it has taken the
initiative to
ensure that, however small the risk of harm, earth will be
protected
from NEOs."
--Peggy Wilhide, Associate Administrator
for Public Affairs,
NASA
"As mid-November 2000 approached, meteor watchers were
anxious to
learn if the dust stream models developed by Asher & McNaught
would
work again. It seemed to be a testable question because --
according
to the models -- Earth was heading for the outskirts of three
debris
streams. [...] The doubters became believers by day's end on Nov.
18th as
sky watchers reported strong meteor activity during all three
encounters.
There is still some uncertainty about the exact times of the
maxima and
their amplitudes, and how those compare to the predictions, but
the
essentials are clear: Asher & McNaught-style models can
predict
Leonid meteor showers, and for more than one year in a row."
-- NASA News, 21
November 2000
(1) PREDICTING LEONID METEORS OFFICIALLY BECAME A SCIENCE LAST
WEEKEND
NASA Science News for November 21, 2000
(2) MYSTERY OF THE CHICXULUB CRATER: ANIMATION SHOWS LIQUID
IMPACT
Space.com, 22 November 2000
(3) BRITAIN JOINS EUROPEAN SOUTHERN OBSERVATORY (ESO)
BBC Online News, 23 November 2000
(4) RESEARCHERS CLAIM TO HAVE FOUND ORDER IN THE DISTRIBUTION OF
GEOLOGIC
'HOT SPOTS'
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) NO ASTEROIDS DROPPED (YET): NASA SAYS IT'S ON TARGET
The Washington Post, 20 November 2000
(6) UK SCIENTISTS REPORT 'ALIEN' LIFE
Environmental News Network, 22 November 2000
(7) FAST ROTATING ASTEROIDS
P. Pravec et al.
(8) RADAR OBSERVATIONS OF ASTEROID 2100 RA-SHALOM
M.K. Shepard MK et al.
(9) SOLAR FLAR STUNS STARDUST
NASA Science News for November 22, 2000
(10) MINING THE MOON, MARS & ASTEROIDS
Planetary Science Research Discoveries (PSRD)
(11) SELF-ORGANISED NONSENSE
Juan Zapata-Arauco <juanwisdomquest@yahoo.com>
(12) MICKEY AND THE GIGGLE FACTOR
Phil Pleit <badastro@badastronomy.com>
(13) AND FINALLY: RECOMMENDED CHRISTMAS BOOK
================
(1) PREDICTING LEONID METEORS OFFICIALLY BECAME A SCIENCE LAST
WEEKEND
From NASA Science News for November 21, 2000
http://science.nasa.gov/headlines/y2000/ast21nov_1.htm?list20392
LEONIDS GALORE
The art of predicting Leonid meteors officially became a science
this
weekend as sky watchers around the globe enjoyed three predicted
episodes of
shooting stars.
November 21, 2000 -- A bright moon, city lights and scattered
clouds weren't
enough to keep the 2000 Leonid meteor shower at bay. Sky watchers
who
ventured outdoors after midnight on Nov. 17th and 18th enjoyed
sporadic
flurries of bright shooting stars numbering more than 200 per
hour over
parts of Europe, Africa, and the Americas.
"I could see plenty of Leonids from [brightly-lit] downtown
Boston,"
reported a reader on Saturday morning after a break in cloudcover
briefly
revealed clear skies. "One meteor was even brighter than the
Prudential
Building!"
This year's Leonid meteor shower consisted of three main episodes
lasting
several hours each. There was a modest flurry of 50 to 100
meteors per hour
on Nov. 17th, followed by two more outbursts of 150 to 450 per
hour on the
18th.
For many North Americans the times of greatest activity coincided
with local
midnight when the constellation Leo was lying low on the eastern
horizon.
Normally, low-hanging radiants are bad news because they make
shooting stars
hard to see. In this case, however, sky watchers were treated to
a vivid
display of Earthgrazing meteors. "Earthgrazers" are
shooting stars that
emerge from just below the horizon and streak through the upper
atmosphere
nearly parallel to the ground. They often display colorful halos
and
long-lasting trails stretching 90 degrees or more across the sky.
"I [started watching] just before 11:00 pm on Friday,"
recounted Pierre
Martin from eastern Ontario. "Even with the Leonid radiant
only 3 degrees
over the eastern horizon, it was obvious that some fairly high
activity was
in progress. Several spectacular Earthgrazers appeared! .... A
most
impressive orange-colored Leonid split the sky in half. It
traveled 70
degrees. A multi-colored one at 11:55 pm really blew me away...
It went from
vivid blue to green to orange before it extinguished and left
behind a train
that lingered for 3 seconds."
The bright Moon was not a serious impediment to meteor watching
as many
feared it would be. The Leonids were bright and they tended to
streak far
from the shower's moonlit radiant.
At 2:45 am EST on Saturday, the Moon was high in the sky when
Marjory
Moeller of Atol, NY, peered out her bedroom window. "I was
immediately
rewarded by a long yellow meteor coming from the east," she
said.
"Incredible sight! It would have been scary if I hadn't
known what it was!"
Minutes later, Jeannie Moorhead of Warwick, NY, says "I saw
an incredible
fireball explode as white as the moon -- it left a very thick
trail that
remained in the sky for at least 5 minutes."
"I never expected a shower [to be] this good with the Moon
up," added Ted
Nichols of the Astronomical Society of Harrisburg, PA.
"During one 15 minute
interval I counted 45 meteors!" Altogether, he saw 275
shooting stars
between 10:30 pm on Friday and 3:30 am on Saturday.
But, not everyone was so fortunate.
"Like a lot of people in the southeastern US, all we saw in
Louisiana were
rain showers -- about 10.5 inches worth at my house,"
lamented meteor
enthusiast Dave Hostetter. "We've been having a drought for
a year and a
half -- I should have known which weekend would get rain!"
"The experts had predicted a strong Leonid shower... and by
golly, that's
what happened here," agreed Kim Youmans in Georgia. "I
can't remember when
it last rained so hard."
Fortunately for such observers, more Leonids are on the way. The
triple-peaked character of this year's shower appears to confirm
new
research that predicts powerful Leonid meteor storms in the
future.
"We're very confident that Leonid storms are coming in 2001
and 2002," says
forecaster David Asher of the Armagh Observatory in Northern
Ireland. "Peak
rates during those years should reach at least 10,000 meteors per
hour when
Earth passes through debris streams from comet
Tempel-Tuttle."
Asher and collaborator Robert McNaught (Australian National
University) drew
attention last year when they predicted the onset of a Leonid
meteor storm
over Europe within minutes of the time it actually occurred. They
had
carefully studied the orbits of myriad debris streams shed by
comet
Tempel-Tuttle during its periodic 33-year visits to the inner
solar system.
By noting the time when Earth passed close to one of those dust
trails,
Asher & McNaught were able to forecast the 1999 Leonids with
unheard-of
precision.
Astronomers have long regarded the Leonids as stubbornly
unpredictable. The
failure of a major Leonid storm to appear in 1899, after
scientists had
urged millions to stay up and watch it, was "the worst blow
ever suffered by
astronomy in the eyes of the public," according to
19th-century astronomer
Charles Olivier. For the next hundred years astronomers fared
little better
with hit-or-miss forecasts based on historical records.
As mid-November 2000 approached, meteor watchers were anxious to
learn if
the dust stream models developed by Asher & McNaught would
work again. It
seemed to be a testable question because -- according to the
models -- Earth
was heading for the outskirts of three debris streams.
Expectations were
tempered by the fact that the expected encounters were not very
close. Earth
would pass half a lunar distance (LD) from one stream and 0.3 LD
from two
others. Researchers suspected that these might be great distances
compared
to the average width of a dust filament. If the outer reaches of
the debris
fields were rarefied, observers might see very little meteor
activity or
possibly none at all. (Note: one "lunar distance" or LD
equals 384 thousand
km, the average separation of the Earth and the Moon.)
The doubters became believers by day's end on Nov. 18th as sky
watchers
reported strong meteor activity during all three encounters.
There is still
some uncertainty about the exact times of the maxima and their
amplitudes,
and how those compare to the predictions, but the essentials are
clear:
Asher & McNaught-style models can predict Leonid meteor
showers, and for
more than one year in a row. Other researchers are already
working to
improve the basic predictive models by, e.g., adding the effects
of
radiation pressure on meteoroids and considering in detail the
trajectories
of debris particles ejected from the parent comet. Decades of
uncertain
Leonid meteor forecasts may soon be a distant memory.
Indeed, the future looks bright for Leonid meteors. In
mid-November 2001
Earth will pass almost directly through three more Leonid dust
streams.
Observers in the Americas, east Asia, Australia and the Pacific
Ocean will
be favored for a good display. Even the Moon is expected to
cooperate -- its
phase will be nearly New, affording dark skies for observers.
So, if rain or clouds (or simply a faulty alarm clock) spoiled
your view of
the 2000 Leonids, don't despair. The best may be yet to come!
===============
(2) MYSTERY OF THE CHICXULUB CRATER: ANIMATION SHOWS LIQUID
IMPACT
From Space.com, 22 November 2000
http://www.space.com/cgi-bin/email/gate.cgi?lk=T2&date=001122&go=/scienceastronomy/planetearth/asteroid_jello_001122.html
By Robert Roy Britt
Senior Science Writer
22 November 2000
When a giant space rock slammed into Earth 65 million years ago
near the
present-day village of Chicxulub on the Yucatan Peninsula, not
only did it
wipe out a lot of dinosaurs, it left behind a huge crater and,
inside that
pock, an even bigger mystery.
A tourist in the jungle outside Chicxulub, about 200 miles (322
kilometers)
west of Cancun, wouldn't see any evidence of the crater, now
buried in eons
of sediment. And she wouldn't suspect she was standing more than
a half-mile
(1 kilometer) above the center of the crater.
But scientists found the crater a decade ago using seismic
monitoring
equipment designed to hunt for oil. And now they have created an
animated
computer model that shows how the crater might have formed -- and
how it
would have left behind an otherwise inexplicable inner ring.
The collision
A comet or asteroid the size of a small city rocked the planet,
sending
giant tsunamis across the ocean and earthquakes reverberating
around the
globe. It also turned much of the Yucatan into mush, scientists
suspect,
causing rock to behave like a thick fluid.
The animation of the Chicxulub event shows how the whole thing
might have
happened, right up to the part where the ring mysteriously
solidifies, like
terrestrial Jell-O in some standard crater mold.
The ring can't be explained. Similar rings have been observed
inside other
craters on Earth and elsewhere in the solar system.
Clues to dino death?
The Chicxulub impact is widely believed to have triggered a mass
dinosaur
die-off, either through a global firestorm or through massive
long-term
environmental changes.
Figuring out how such a ring might form would help researchers
understand
the chemical and physical processes that go on during an impact,
and whether
and how such events might have caused mass extinctions in the
past.
"This kind of research is crucial if we want to understand
the environmental
knock-on effects of giant impacts," said Benny Peiser, a
researcher who
focuses on neo-catastrophism at Liverpool John Moores University.
"The truth
of the matter is that despite 20 years of impact research, we are
still far
from knowing even the main mechanisms of impact-related mass
extinctions."
Such research could also help humanity prepare for the effects of
any
possible future impacts, and it might also shed light on how
plain old
earthly landslides occur.
Hidden crater
Around 1980, Luis and Walter Alverez suggested that an impact
might have
been responsible for the death of the dinosaurs. The race was on
to find
evidence of a crater.
The Chicxulub crater was discovered 10 years later. Much of it
lies under
the ocean, and all of it is hidden under 65 million years of
sediment. The
crater is estimated to be 100 to 150 miles (160 to 240
kilometers) wide.
Gareth Collins, a postgraduate student at Imperial College in the
U.K.,
presented the animation at the Geological Society of America's
annual
meeting earlier this month. He detailed the Chicxulub event for
SPACE.com:
The tremendous energy of the impact shattered the underlying
bedrock into a
pile of rubble -- small rocks and large boulders. It also
generated
vibrating acoustic waves, Collins suspects. These waves then
supported the
weight of the rock, reducing friction deep down in the pile and
allowing the
whole mess to slip around.
Collins calls the process "acoustic fluidization," and
he likens it to a
pile of sand. If the pile is steep enough, the grains near the
top of the
pile can slip. But the sand at the bottom has lots of weight
pushing down on
it, creating friction and holding it in place.
"In order to allow the whole sand pile to move, some process
must either
reduce the friction between the grains throughout the pile, or
relieve the
weight of the overlying sand."
Collins says the same process relieved the weight in the
Chicxulub rubble
pile, allowing otherwise solid material to slosh side-to-side and
up-and-down.
The crater collapsed, forming a towering mound in the center that
was two or
three times the height of Mount Everest. An outer rim formed on
the crater,
some 62 miles (100 kilometers) wide.
"The central uplift would then have collapsed itself to form
a concentric
ring structure analogous to the ripple formed when a sugar lump
is dropped
into a cup of tea," Collins said. "In the case of
crater collapse, however,
the fluidization of the surrounding rock is only temporary --
once the
fluidization ceases, the collapse is halted and the internal
concentric ring
structure remains."
It's this sudden solidification that leaves scientists scratching
their
heads.
"This research is at a very early stage and hasn't overcome
the biggest
difficulty," says Peiser, who was not involved in the work.
"If the
punctuated material turns fluid and collapses within a very short
time, how
can a central peak become frozen almost instantly in order to
survive as a
feature instead of flatten out?"
Collins worked with Jay Melosh, a geophysicist at the University
of
Arizona's Lunar and Planetary Laboratory, and others, to develop
the
computer animation based on seismic data. Collins said that while
geologists
are skeptical of the model, his colleagues who study asteroid
impacts
generally agree with the idea. Peiser acknowledges that the
concept is
"gaining currency."
But even those who support fluidization disagree on exactly how
it occurs.
It might be caused by the heat of impact, some say, rather than
by acoustic
waves.
Copyright 2000, Space.com
================
(3) BRITAIN JOINS EUROPEAN SOUTHERN OBSERVATORY (ESO)
From the BBC Online News, 23 November 2000
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1035000/1035832.stm
Observatory coup for UK astronomers
British astronomers have been told they can join the project that
will
operate the largest optical telescope in the world.
The government set out the details of its science budget on
Wednesday and
indicated that substantial funds required for UK membership of
the European
Southern Observatory (Eso) would be made available.
Eso's main facility is the Very Large Telescope at the Paranal
Observatory
in Chile, due to become fully operational next year. Its advanced
optics
technology is expected to give unprecedented views of the
Universe - but it
does not come cheap.
The initial Eso joining fee is £70m with annual payments of
£12m after that.
The Particle Physics and Astronomy Research Council (Pparc) will
have to
contribute to these costs and this means some existing astronomy
projects
may be cut back.
Larger British interests such as the UK Infrared Telescope or the
Isaac
Newton Group of Telescopes on Hawaii could be threatened. As
could UK
participation in a number of European Space Agency missions.
Positive response
Eso membership would give UK astronomers access to the optical
array at the
La Silla observatory, also in Chile. But it is the VLT which is
the most
exciting prospect.
It consists of four 8.2-metre and several 1.8-metre telescopes.
These
telescopes can be used in combination as a giant interferometer
to mimic a
truly massive, single telescope. And advanced optics ensure the
VLT gets the
sharpest view of an object despite having to look through Earth's
turbulent
atmosphere.
Professor Mike Edmunds, who recently chaired the UK Astronomy
Review Panel
which set out a programme of opportunities and priorities for the
next 10-20
years, said of the intention to join the Eso: "This is
excellent news for UK
science and lays the foundation for cutting edge research over
the next 10
years.
"British astronomers will be delighted by the government's
rapid and
positive response to their case."
Science investment
Announcing the allocations from the science budget to the UK's
seven
research councils, Trade and Industry Secretary Stephen Byers
said research
into the role of genes would take a major share of the money
available.
He said £252m would be invested by the councils in three key
areas:
Genomics - £110m will allow researchers to develop new
diagnostic tests and
new drugs based on the information gleaned in the human genome
project;
e-science - £98m will develop the new high-power computing
resources that
will increasingly be needed to handle the vast amounts of
research data
shared around the world, principally over the net;
Basic technology - £44m will be used to fund new technologies
such as
quantum computing, bio-engineering, photonics and nanotechnology
- areas
which will form the basis of major new industries of the future.
In addition, the research councils would be given a further
£100m for work
in their own specific areas, Mr Byers said. It is from this money
that Eso
membership would be funded.
The announced money is part of an overall package of government
science
investment amounting to £725m over the next three years.
"We have the potential to lead the world in many areas, but
to do so will
require substantial investment," Mr Byers said.
Copyright 2000, BBC
===============
(4) RESEARCHERS CLAIM TO HAVE FOUND ORDER IN THE DISTRIBUTION OF
GEOLOGIC
'HOT SPOTS'
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Southern Methodist University
Dallas, Texas
Reporters may contact:
Ellen Mayou, SMU Public Affairs
(214) 768-7659, emayou@mail.smu.edu
November 15, 2000
SMU RESEARCHERS FIND ORDER IN THE DISTRIBUTION OF GEOLOGIC 'HOT
SPOTS'
DALLAS (SMU) -- Researchers at Southern Methodist University have
discovered
a symmetrical distribution for the "hot spots" on the
Earth's surface.
Scientists have located 47 places on the Earth's surface where
volcanic
activity unrelated to plate tectonics occurs. These areas include
Hawaii,
Yellowstone, Iceland and the Galapagos Islands. These hot spots
mark the
sites of ancient "mantle plumes" where huge amounts of
volcanic material
rose from deep within the Earth. Today, residual material
representing the
tails of these mantle plumes still comes up at these hot spots.
Although previous studies have recognized that hot spots tend to
occur in
broad clusters, an orderly arrangement in their distribution had
not been
reported. SMU geologists Rebecca Ghent and Douglas Oliver studied
the
location of the major hot spots and determined that a
disproportionate
number occur at latitudes between 20 and 30 degrees north and
south of the
equator. Their observation became much more significant when the
hot spots
were weighted according to the amount of volcanic material that
they
produced. Statistical analysis shows that the likelihood of this
distribution arising by chance is less than one percent.
"This hints that there is something going on deep within the
Earth that
hasn't been suspected before," Oliver said. Although it is
widely accepted
that mantle plumes rise due to buoyancy, Oliver said that if
buoyancy were
the only factor, this should result in a random distribution of
hot spots.
The symmetrical distribution of hot spots on either side of the
equator
suggests a process that channels material to the source region
for the hot
spots 1,800 miles below the
surface. Oliver and Ghent are currently investigating processes
within the
Earth that may be responsible for this phenomena.
Oliver and Ghent said their observation may shed light on other
geological
phenomena, such as the development of superplumes, which are
clusters of
mantle plumes arriving together at the Earth's surface.
Scientists believe
that massive superplume events are responsible for some of the
major changes
that have occurred on the Earth, such as the breakup of the
supercontinent
known as Pangea into the present continents.
Ghent and Oliver presented their research Nov. 15 at the 112th
annual
meeting of the Geological Society of America in Reno, Nevada.
[NOTE: Diagrams supporting this release are available at
http://www.smu.edu/~newsinfo/releases/00071.html]
=================
(5) NO ASTEROIDS DROPPED (YET): NASA SAYS IT'S ON TARGET
From The Washington Post, 20 November 2000
http://www.washingtonpost.com/wp-dyn/articles/A44717-2000Nov20.html
NO ASTEROIDS DROPPED
Letter to the Editor
Monday, November 20, 2000; Page A20
We at the National Aeronautics and Space Administration were
astonished by
the charge that we may be "dropping the ball" in the
search for asteroids
that may threaten earth [news story, Oct. 16].
While NASA welcomes the British plan to build a large facility
for detecting
Near Earth Objects (NEOs) smaller than one kilometer in diameter,
the search
remains largely a NASA-led effort.
That's not just a self-assessment. The British Task Force on
Potentially
Hazardous NEOs prominently states that the United States is
"doing far more
. . . than the rest of the world put together" and that the
effort is
"progressing well" and has definitely not, as reporter
T. R. Reid stated,
"fallen far behind schedule."
The Post article cited the task force estimate that as many as
2,000 Near
Earth Objects may be more than one kilometer in diameter.
According to the
best current estimate, there are no more than 700 to 1,100
objects of this
size. The NASA-led effort has found almost half of all the large
asteroids
that might threaten earth, including more than 100 in the past
year alone.
Mr. Reid reported that NASA spends $2 million annually on
locating and
identifying each of these objects; the true figure is nearly
double that.
Long-period comets, which cause a modest fraction of the
collisions suffered
to date on earth, cannot be predicted through the NEO survey.
Their source
is the Oort cloud, a vast spherical cloud of comets at distances
greater
than 10,000 times the distance of the earth from the sun. It is
impossible
to detect objects the size of cometary nuclei at even a fraction
of that
distance, but NASA has planned several missions to better
understand these
comets.
NASA has not "dropped the ball"; it has taken the
initiative to ensure that,
however small the risk of harm, earth will be protected from
NEOs.
PEGGY WILHIDE
Associate Administrator for Public Affairs
National Aeronautics and Space Administration
Washington
© 2000 The Washington Post Company
==================
(6) UK SCIENTISTS REPORT 'ALIEN' LIFE
From Environmental News Network, 22 November 2000
http://www.enn.com/news/wire-stories/2000/11/11222000/upi_alien_40377.asp
Wednesday, November 22, 2000
By United Press International
Scientists in Wales said they discovered what may be a tiny form
of
primitive alien life that a passing comet may have dropped into
Earth's
atmosphere, London's Daily Mail newspaper reported today.
Researchers said that in the filter of a high-flying balloon
operated by the
Indian Space Research Organization, they found a strain of
bacteria unlike
anything on Earth. The bacteria were found at an altitude of 10
miles and
scientists from the ISRO, Cardiff University and the University
of Wales
College of Medicine said it may have come from a comet on a close
approach
to earth, according to the Daily Mail.
Prof. Chandra Wickramasinghe, who is based at Cardiff University,
said the
discovery marked "the first time we have had direct evidence
for the
hypothesis that comets seed life on other planets."
Wickramasinghe and astronomer Fred Hoyle suggested the theory of
"panspermia" more than two decades ago, that the seeds
of life, either DNA
or microbes, could be carried by asteroids or comets and dropped
off on
planets such as earth to germinate life.
The bacteria found in the balloon's filter "is a hitherto
unknown strain,"
Wickramasinghe said. "It is so different from anything we've
seen before
that there are only two possible explanations."
One, he told the Daily Mail, is that "organisms have been
lifted from the
earth to great heights in the skies and have somehow multiplied
there and
changed over time." The second, he said, is "that this
is an example of
primitive alien life."
The newspaper said samples of the bacteria are under study at
Cardiff's
Astrobiology Center, which Wickramasinghe and other scientists
from ISRO,
Cardiff University and the College of Medicine have teamed up to
form.
Wickramasinghe rejected suggestions that the bacteria might the
result of
contamination by earthly organisms. He said ISRO had imposed
stringent
sterile conditions aboard the balloon.
"The most recent geological evidence now suggests life on
earth may be 4
billion years old," the professor was quoted as saying.
"That is a very
significant time because it was a period when the earth was
pounded by
comets and meteors."
But his theory is not universally accepted in scientific circles.
The Daily
Mail quoted Alan Penny, an astronomer at Britain's Rutherford
Appleton
Laboratory, as warning that "we would be cautious about
jumping to
conclusions."
"Extraordinary claims," he said, "need
extraordinary evidence."
Copyright 2000, United Press International
All rights reserved
============
(7) FAST ROTATING ASTEROIDS
Fast rotating asteroids 1999 TY2, 1999 SF10, and 1998 WB2
Pravec P, Hergenrother C, Whiteley R, Sarounova L, Kusnirak P,
Wolf M
ICARUS 147: (2) 477-486 OCT 2000
An analysis of our photometric observations of near-Earth
asteroids 1999
TY2, 1999 SF10,and 1998 WB2 has revealed their rotation periods
to be 7.2807
+/- 0.0003, 2.4663 +/- 0.0005, and 18.8 +/- 0.3 min,
respectively, Their
rotations are so fast that the bodies cannot be held together by
self-gravitation alone, and must therefore be monoliths. Their
absolute
magnitudes, 23.1 +/- 0.3, 24.0 +/- 0.5, and 22.1 +/- 0.2,
respectively,
indicate that they are small bodies with mean diameters in the
range 60-120
m. The current statistics of asteroid spin rates vs size suggest
that the
range where monoliths start to dominate among asteroids is below
a diameter
of about 200 m, corresponding to H approximate to 22, as
suggested by
P.Pravec and A. W. Harris (2000, Icarus, in press). (C) 2000
Academic Press.
Addresses:
Pravec P, Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov,
Czech
Republic.
Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech
Republic.
Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA.
Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA.
Charles Univ Prague, Astron Inst, CZ-18000 Prague, Czech
Republic.
Copyright © 2000 Institute for Scientific Information
=================
(8) RADAR OBSERVATIONS OF ASTEROID 2100 RA-SHALOM
Radar observations of Asteroid 2100 Ra-Shalom
Shepard MK, Benner LAM, Ostro SJ, Harris AW, Rosema KD, Shapiro
II, Chandler
JF, Campbell DB
ICARUS 147: (2) 520-529 OCT 2000
We report Doppler-only (cw) radar observations of near-Earth
Asteroid 2100
Ra-Shalom obtained at the Arecibo Observatory using a transmitter
frequency
of 2380 MHz (12.6 cm) on 1984 Aug. 18-22. Weighted and filtered
sums of cw
echoes achieve a maximum signal-to-noise ratio of 74 and cover
the asteroid
in rotation phase. A weighted sum of all cw spectra gives an
opposite
circular (OC) radar cross section of 1.13 +/- 0.40 km(2) and a
circular
polarization ratio of 0.31 +/- 0.02. Inversion of echo edge
frequencies
yields a convex hull with an elongation (maximum breadth/minimum
breadth) of
1.15 +/- 0.03 and places a lower bound on the maximum pole-on
dimension of
2.4 km/cos delta, where delta is the angle between the radar
line-of-sight
and the asteroid's apparent equator. Ra-Shalom has one of the
least
elongated pole-on silhouettes of the near-Earth asteroids for
which similar
shape information from radar observations is available.
Ra-Shalom's
effective diameter (diameter of a sphere with equal
cross-sectional area) is
constrained to a range of 2.4-3.6 km. We use a two-component
radar
scattering model to remove the "diffuse" contributions
from Ra-Shalom's
radar cross section and obtain a surface bulk density estimate of
1.1-3.3 g
cm(-3). When compared with reported bulk densities and porosities
of
meteorites, our results are consistent with either: (1) a C-class
asteroid
with carbonaceous-chondritic composition, effective diameter
2.6-3.6 km, and
surface porosity <70%; or (2) an S-class asteroid with
ordinary-chondritic
or stony-iron composition, effective diameter 2.4-2.6 km, and
little or no
surface regolith. Ra-Shalom's near-surface roughness appears to
be globally
heterogeneous. (C) 2000 Academic Press.
Addresses:
Shepard MK, Bloomsburg Univ Penn, Dept Geog & Geosci,
Bloomsburg, PA 17815
USA.
Bloomsburg Univ Penn, Dept Geog & Geosci, Bloomsburg, PA
17815 USA.
CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA.
Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA.
Cornell Univ, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853
USA.
===============
(9) SOLAR FLAR STUNS STARDUST
NASA Science News for November 22, 2000
http://science.nasa.gov/headlines/y2000/ast22nov_1.htm?list20392
One of the most intense solar radiation storms in decades
temporarily
blinded NASA's Stardust spacecraft earlier this month.
November 22, 2000 -- Quick-thinking engineers and scientists
helped NASA's
Stardust spacecraft survive a storm of high-energy particles from
the Sun
after a recent solar flare.
Stardust -- a NASA mission to return samples from comet P/Wild 2
-- was only
1.4 AU (130 million miles) from the Sun on Nov. 8th when a
powerful solar
flare erupted. Engineers from the Stardust team were a little
worried, since
they had heard the resulting radiation storm was the fourth
largest since
1976. A cloud of high-energy particles was heading for Earth and
for
Stardust.
FULL STORY at
http://science.nasa.gov/headlines/y2000/ast22nov_1.htm?list20392
=============
(10) MINING THE MOON, MARS & ASTEROIDS
From Planetary Science Research Discoveries (PSRD)
http://www.soest.hawaii.edu/PSRdiscoveries/Nov00/mining.html
Mining the Moon, Mars, and Asteroids
Written by G. Jeffrey Taylor
Hawai'i Institute of Geophysics and Planetology
An international group of scientists, mining and aerospace
engineers, policy
makers, and other specialists met in Golden, Colorado to discuss
the use of
space resources. Space Resources Roundtable II was held at the
Colorado
School of Mines, and was sponsored by the School of Mines, NASA,
and the
Lunar and Planetary Institute. Participants discussed lunar,
martian, and
asteroidal resources, along with economic and legal aspects of
using
extraterrestrial resources. This report focuses on lunar
resources.
Manufacture of useful materials on the Moon, Mars, or asteroids
requires
extensive use of what we know about those places through studies
of lunar
samples and meteorites from asteroids and Mars. It is applied
cosmochemistry.
Lunar Solar Power
Energy specialists point out that we need alternatives to fossil
fuels. They
give several reasons. There are environmental problems with
burning carbon.
The traditional fuels will eventually run out. Perhaps most
important,
increasing the standard of living in developing nations requires
a huge
increase in the supply of energy.
Solar power has often been touted as an answer to the world's
energy
problems. However, it is not very efficient. A given place on
Earth is dark
half the time. Clouds and dust reduces the amount of solar energy
by another
50%. And except near the equator, the low angle of sunlight
causes loss to
the air, cutting the amount of energy by yet another 50%. All
those
reductions amount to eight times less solar energy reaching
Earth's surface
than arrives from the Sun.
The obvious thing to do is to tap the Sun's energy in space. The
idea of
space power systems has been around since the late 1960s. New
technology
makes it more attractive than it was at first. Its biggest
problem is the
cost of launching lots of stuff from the ground to orbit. But
suppose almost
all the needed materials were already there? David Criswell
(University of
Houston) has been arguing for years that the materials are
already there--on
the Moon. It just takes some manufacturing facilities to produce
the needed
parts and pieces.
Solar power could be generated in space and beamed to the ground.
The amount
of material needed to construct a power satellite is large, hence
expensive
to transport from the surface of the Earth. It may be more
cost-effective to
bring the ingredients from the lunar surface--or even use the
Moon to
collect the solar power.
Criswell believes that solar power stations should be located on
the Moon.
He proposes building them on the right and left sides of the
Earth-facing
side of the Moon. This ensures a continuous supply of power to
the earth.
Solar cells would collect sunlight and transmit the energy to
microwave
transmitters. The microwave antennas would beam the energy to
Earth, where
it would be received by other antennas on the ground. Criswell
says that the
solar cells on the Moon would not need to be highly efficient.
Instead, they
could cover a lot of real estate. The trick is to make the solar
cells and
antennas on the Moon.
Alex Ignatiev, Criswell's colleague at the University of Houston,
proposed a
solution. An expert in materials science, Ignatiev presented the
basic
design for a robotic solar-cell maker. It would roll over the
lunar surface,
leaving a trail of solar cells behind. As the surface passed
beneath the
rover, concentrated sunlight would melt the surface. This would
cool quickly
to make a smooth, glassy surface. Another system would extract
silicon from
the lunar soil by a vaporization process and deposit it in thin
films on the
glass surface. Depositing thin films requires a strong vacuum.
The Moon
provides such a vacuum. The flimsy lunar atmosphere has a
pressure about a
trillionth that of the Earth.
The result would be an extensive network of solar cells. They
would probably
not be very efficient, but Ignatiev suggested that covering a
large area
with solar cells would overcome that problem. Although Ignatiev
has lots of
work to do to prove that the concept will work, most participants
thought it
was a promising way to produce power on the Moon. Perhaps
Earthlings will
prosper during the coming decades from an inexhaustible supply of
solar
power from the Moon.
Lunar Alchemy: Dirt into Products
Schemes to extract oxygen from the lunar soil have been around
for a long
time. Almost all of them also produce other products as well,
such as iron
and titanium. Many require fairly high temperatures, hence a lot
of energy.
A few processes use hydrofluoric acid. These do not need a high
temperature,
but hydrofluoric acid is extremely toxic and corrosive.
Steve Gillette (University of Nevada, Reno) studies ways to
separate
elements on Earth. He suggested using organic chemicals to
extract useful
elements at a low temperature. Once lunar soil is dissolved into
a mixture
of organic liquids, useful materials could be separated. For
example,
silicon-based ceramics could be made at low temperature. These
could be
useful for many purposes at a lunar base, including making
molecule-sized
machines (so-called molecular nanotechnology). If the Moon
becomes an
important part of Earth's commerce, cutting-edge technologies
will be
essential.
Several scientists talked about their experiments on extracting
oxygen,
using the more traditional high-temperature techniques. These
included James
Blacic (Los Alamos National Laboratory), Giovanni De Maria
(University of
Rome), and H. Yoshida and his colleagues (Tokyo Institute of
Technology).
All use some kind of mechanism to fluff up moon dirt to make it
easier to
react with hydrogen gas. (The experiments actually use simulated
moon dirt.
Real lunar samples are too precious to use until a technology has
been
tested thoroughly with fake moon dirt.) De Maria uses ultrasound
to shake a
column of dirt. The others use the force of flowing hydrogen gas
to make the
pile of dirt behave like a fluid. Blacic's apparatus ionizes the
hydrogen,
making it reactive. The others heat the gas and dirt.
All the approaches produced water by reaction of the hydrogen
with the soil.
On the Moon, this water could be used for life support. Most
important, it
could be split into hydrogen and oxygen to use as rocket fuel.
The
experiments also produced metallic iron. That could be used as a
building
material or for electrical cables, if we could figure out an
efficient way
to separate it from the rest of the dirt.
Larry Taylor (University of Tennessee) has been working on lunar
samples
since the first batch was brought back from the Moon. He has also
worked on
ways to remove oxygen from lunar soil. Recently, he has been
working with a
team on understanding the optical properties of the lunar
surface. This is
important to understanding many remote-sensing observations of
the Moon.
While doing that work, he learned that the smallest soil grains,
those
smaller than 20 micrometers, are coated with tiny particles of
metallic
iron. The particles are only 10 to 100 nanometers across.
These two images show the distribution of iron in a collection of
tiny lunar
soil grains. Those labeled 'plag' and marked with arrows (for
plagioclase)
do not contain iron in their interiors. This is expected because
lunar
plagioclase contains very little iron. However, the edges of the
plagioclase
grains are decorated with blebs of metallic iron. This makes the
plagioclase
magnetic. Arrows in the righthand image point to two plagioclase
grains
coated with metallic iron which show up as bright rings. The
other mineral
grains also contain iron blebs, but the coating is
indistinguishable from
the iron oxide in the interiors.
What's that have to do with lunar resources? It is important for
two
reasons. First, it may make it possible to filter out the finest
lunar dust.
Rocky dust can be a health hazard to future workers on the Moon.
It also can
collect on door seals, allowing air to escape from pressurized
houses. The
minute iron particles make all tiny lunar grains magnetic. So,
magnets will
be able to remove the dust from the air and could be used to
clean surfaces.
Second, the magnetic properties of the tiny grains give us a way
to
concentrate the finest dirt. By heating, the tiny iron grains
will combine
into larger grains that can be separated. Also, hydrogen is a
useful element
in lunar industry. Because it is delivered to the Moon by the
solar wind, it
occurs in the surfaces of soil grains. A pile of small particles
has a
greater surface area than a pile of large ones, so hydrogen is
more abundant
in small grains than large ones. Thus, separating small grains
also
concentrates hydrogen.
Drilling Holes in Planets
Some mining engineers are making important contributions to
understanding
how to explore the subsurface and how to mine asteroids. Others
are trying
to determine how to drill for water on Mars. Those places are
very different
from Earth, so the engineers must modify their equipment and
techniques.
Dale Boucher (Northern Centre for Advanced Technology, Sudbury,
Ontario) has
used his vast experience in mine construction to devise a
lightweight,
power-stingy drill to use on Mars. Jim Blacic has also been
working on how
to drill on Mars. He and his colleagues have identified many
components of
terrestrial drilling rigs that could be easily adapted for use on
Mars. He
pointed out, however, that no existing drill could be used as is.
Leslie Gertsch (Michigan Technological University) described how
an asteroid
could be mined, once a resource was identified on it. She brought
up the
important point that the approach depends on the make-up of the
asteroid.
For example, it might be composed of a mixture of ice and rock.
The asteroid
might be weak, easily broken rock, or very strong rock. It might
even be
made of metallic iron. This shows how important it will be to
thoroughly
characterize an asteroid before deciding how to mine it.
The Future
People are eventually going to be working and living in space.
Construction
and operation of lunar solar power stations may make that happen.
Or perhaps
it will happen to support a thriving space tourism business.
Whatever drives
it, there will be a need to use the resources available in space.
It is too
expensive to drag all the needed ingredients up from the Earth.
The
resources are available on the Moon, Mars, and asteroids.
Participants in
the Space Resources Roundtable agree that we need to explore
extraterrestrial bodies for resources and to learn how to extract
those
resources from them. Experts in the mineralogy and chemical
composition of
extraterrestrial materials will play important roles in the
search and
mining of space resources. Like Earth explorers through the ages,
we must
live off the land and a new breed of scientist, the applied
cosmochemist,
will be there to see it happen.
============================
* LETTERS TO THE MODERATOR *
============================
(11) SELF-ORGANISED NONSENSE
From Juan Zapata-Arauco <juanwisdomquest@yahoo.com>
Dear Benny:
In the 11/11/2000 issue of New Scientist we can read an
interesting opinion
written by Per Bak the creator of the theory of self-organized
criticality:
"More spectacular is the application (of the theory of
self-organized criticality) to biology. Could it be that mass
extinctions
are intrinsic outcomes of the dynamics of evolution? Try
considering
them as co-evolutionary avalanches, where extinction of one
species
leads to the extintions of others in a chain reaction. Compare
this to the
traditional enviroment of scientific thought, dominated by the
view that
nature is in a state of equilibrium and balance. This leads (sic)
to the
unquestioned (sic) assumption that mass extinctions must be
caused by
external cataclysmic events--such as meteorites
(sic)."
This can be reached in
"http://www.newscientist.com/opinion/opinion.jsp?id=ns226451"
Best regards,
Juan
===============
(12) MICKEY AND THE GIGGLE FACTOR
From Phil Pleit <badastro@badastronomy.com>
Benny--
The article from the Rocky Mountain Collegian about asteroid
impacts was
ostensibly a humor column. It was written in a student newspaper
at Colorado
State University, and really shouldn't be taken seriously. It
would have
been nice had the facts been straight, but a lot of that
stuff was exaggerated on purpose (though it wouldn't surprise me
if some
people really do worry that mining the Moon might affect
tides...).
Anyway, there was a disclaimer at the bottom that was not in the
Exite News
version you published that should make this clear:
"Columnist Disclaimer: WARNING! The preceding column depicts
acts that are
cruel and unusual toward hippies. Do not feed penguins suntan
lotion for
fear of spontaneous combustion. Consult your local hypnotherapist
for the
latest stock market information. If Cartman owns a Chewbacca
action figure,
you must acquit. READ AT YOUR RISK."
I found it on the web at http://www.collegian.com/story.cfm?id=6076.
-Phil Plait,
ex-humor columnist for a
(different) student newspaper
==============
(13) AND FINALLY: RECOMMENDED CHRISTMAS BOOK
Good news for the undecided: Reader's Digest have made Duncan
Steel's TARGET
EARTH one of their two recommended Christmas books. See:
http://shopping.readersdigest.com/rdsah/
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