CCNet 121/2001 - 16 November 2001

"Magnetic spherules from several localities in Hungary were analyzed
and the results were compared to analytical data of similar objects found
in Japan, Slovakia and Hawaii. The studies were carried out using
micro-PIXE technique. On the basis of morphological features and
elemental compositions it was concluded that signs of a new meteoritic
impact could be found."
--G. Szoor et al., Magnetic spherules: Cosmic dust or
markers of a meteoritic   impact?

"A lot of people are paying attention to researchers Rob McNaught of
the Australian National University and David Asher of the Armagh
Observatory. They have been saying for months that two peaks would occur,
one of 2,500 meteors per hour over North America, and another of 15,000
over Australia. Last month, however, they revised their forecasts
downward, to 800 and 8,000, respectively. Peter Jenniskens, of NASA's Ames
Research Center and the SETI Institute, has been prognosticating
meteor showers in recent years, too. He published an updated
forecast just weeks ago, calling for a peak hourly rate over North
America of 4,200 shooting stars -- more than one every second. Then there's
Markku Nissinen, Tom Van Flandern and Finnish researcher Esko Lyytinen, who
predict a peak of 2,000 per hour for North America. It's a good thing
these guys aren't trying to pin down whether and where the next hurricane
will strike."
--Rob Britt,, 15 November 2001

SHOWER, 15 November 2001

    Andrew Yee <>

    Ron Baalke <>

    C.H. Chen et al.

    A.N. Halliday et al.

    A.A. Sukhanov

    M. Ross

    M.C. Nolan et al.

    A. Dell'Oro et al.

     G. D'Abramo  et al.

     G. Szoor et al.

     W.J. McNeil et al.

     R Malhotra et al.

     Yahoo! News, 15 November 2001

     Harvey Leifert <>

     Christian Koeberl <>

     Duncan A. Lunan <>

     Hermann Burchard <>


>From, 15 November 2001

By Robert Roy Britt
Senior Science Writer

This weekend, NASA meteor scientist and forecaster Bill Cooke will be in
Hawaii, where he thinks the 2001 version of the Leonid Meteor shower will
put on its best show -- a full-fledged storm of shooting stars. Cooke has
been studying these things for years, and he's predicting a peak hourly rate
of 1,400 meteors for 3 a.m. local time Sunday morning.

"I'm ready to put my money where my mouth is," Cooke said in a recent

Almost no one is following Bill Cooke to Hawaii.

A lot of people are paying attention to researchers Rob McNaught of the
Australian National University and David Asher of the Armagh Observatory.
They have been saying for months that two peaks would occur, one of 2,500
meteors per hour over North America, and another of 15,000 over Australia.
Last month, however, they revised their forecasts downward, to 800 and
8,000, respectively.

Peter Jenniskens, of NASA's Ames Research Center and the SETI Institute, has
been prognosticating meteor showers in recent years, too. He published an
updated forecast just weeks ago, calling for a peak hourly rate over North
America of 4,200 shooting stars -- more than one every second.

Then there's Markku Nissinen, Tom Van Flandern and Finnish researcher Esko
Lyytinen, who predict a peak of 2,000 per hour for North America.

It's a good thing these guys aren't trying to pin down whether and where the
next hurricane will strike.

Why so different?

In all fairness, the wildly disparate forecasts made by these four respected
research groups are rooted in a known, but little-understood scientific
phenomenon: The space dust that causes the Leonid meteor shower spreads out
more and more every year.

The dust -- mostly particles no larger than sand grains -- is the exhaust of
comet Tempel-Tuttle, which orbits the Sun every 33 years.

On each pass, fresh material is boiled off the comet's core by the Sun. And
because the comet's orbital path is constantly changing by a small amount,
each dust trail is in a slightly different location. Some of the dust Earth
will encounter this weekend has been floating through space since before the
United States was a country.

Cooke thinks of each trail as a river. As Earth wades through a dust stream,
it is shallow at the edges -- less dust. The river is deepest -- containing
the highest concentration of dust -- in the middle.

Exactly why the dust moves, and by how much, is what vexes the scientists.

Larger particles are nudged into new paths by the gravity of the Sun, Earth
and the other planets, Cooke explained. Smaller bits are less affected by
gravity, but they are bullied around somewhat by the pressure of solar
radiation -- charged particles that rush constantly outward from the Sun.

History as a guide

One of the most dramatic Leonid showers in history, which occurred in 1833,
involved a pass through a dust trail laid down roughly 100 years earlier.
The dust was concentrated into a relatively narrow stream, researchers
suspect. Some of the 2001 forecasts are based in part on what happened in

There is no firmly established rate of spreading to factor in, however, and
the planet will plunge through at least three dust streams this weekend --
from 1866, 1767 and 1699.

The North American peak will be related to the 1767 stream. The result will
almost certainly be something less than what occurred in 1833, when people
witnessed a storm of meteors -- one observer in Boston reportedly saw more
than 8,000 meteors in just 15 minutes.

For scientists, an hourly rate of 1,000 shooting stars qualifies a meteor
shower to be called a "storm."

With all their adjustments in place, each research group now thinks it's got
2001 figured out.

The differences in their methods are subtle. Jenniskens told that
his work is based in part on observations of the 1999 and 2000 Leonids from
aircraft. He expects that Earth will pass closer to the middle, densest part
of the stream than do the other forecasting teams.

Asher and McNaught have looked at historical accounts of meteor showers
going back to 1833. Their recent downward revision was based on the
inclusion of an "aging parameter," developed by Esko Lyytinen's team, which
accounts for how solar radiation might disperse the dust.

Asher said the large uncertainties still associated with meteor forecasting
mean that no one knows exactly what's coming Sunday morning. "The estimates
of meteor rates by ourselves, by Lyytinen, by Jenniskens, and even our 'old'
model, are all within the bounds of possibility," he said.

Cooke, whose expectations are the most modest, thinks the other groups are
too optimistic in their calculations of how much dust will be left in the
center of a "river" that has been flowing through space for centuries. He
said meteor data from the 1833 showers and other historical sources are
likely inaccurate, being drawn from nothing more than old newspaper

So Cooke's calculations are based only on what has been observed each
November since 1966.

Yet even Cooke has hedged his bet. Before he left for Hawaii, he coordinated
with researchers from NASA and elsewhere, setting up groups that will fan
out to New Mexico, Guam and the Gobi desert in Mongolia. Each will train a
couple of video cameras on the sky to record shooting stars for later
research, in an effort to improve future predictions.

What about the rest of us?

But for those of us who can't fan out, what's the best advice?

For that answer, we turned to Joe Rao, who has written several scientific
papers and popular articles about meteor showers. Like many American
scientists who've been monitoring the changing forecasts and making travel
plans, Rao told us he'll be watching the Leonids from the Southwest.

And what does Rao expect to see?

Rao is familiar with difficult forecasting challenges. He's also a
meteorologist, dealing nightly with Mother Nature's whims for viewers of
News 12 in Westchester, New York. And he is clearly more comfortable
predicting the weather.

But he can't resist throwing his hat into the Leonids forecasting ring. He
does so conservatively, recalling that past Leonid meteor showers have
produced fewer shooting stars than expected.

He said the forecasts of Esko Lyytinen and his colleagues have been the most
consistent over the past couple of years. But even those have been off by a
factor of two.

"If pressed for a prediction of rates for the Leonids over North America,
I'd suggest 1,000 to 1,200 per hour," he said, though he added that it could
go as low as 800.

Either way, that's more than 13 every minute. One every few seconds. An
event of a lifetime for anyone lucky enough to see it.

Copyright 2001,


>From Andrew Yee <>

The Guardian, 15 November 2001,3858,4298889,00.html

Astronomers are gearing up for one of the greatest shows on Earth

By Duncan Steel

The space shuttle is being grounded this Sunday, and the Hubble Space
Telescope will be steered to look away for the return of the Leonid meteors.

Although they pose no danger to us on the ground because the atmosphere
shields them out, tiny meteoroids pose (rather literally) a bumper danger to
satellites or astronauts in orbit. That's why the space shuttle has not
flown in mid-November for the past several years, and Hubble is
re-oriented to point its rear end towards the direction from which these
minute projectiles arrive. For the three inhabitants of the space station,
it's a matter of sit tight and keep your fingers crossed. Ditto commercial
satellite operators with billions invested.

This will not go on forever. We are in a brief period of heightened
activity. Although the Leonid meteor shower is seen every year on November
17-18, its prominence follows a regular cycle. Every 33 years there is a
sequence during which the sky really lights up on the same date, and we have
records dating back to AD 902 to prove it.

In recent centuries, phenomenal storms in 1799, 1833, 1866 and 1966 have
occurred. While 1999 and 2000 were spectacular, the predictions for 2001 and
2002 are better still.

The regular period of 33 years results from the length of time the parent
comet, on its elongated orbit, takes to circuit the Sun. This comet, named
Tempel-Tuttle, was discovered by German and American astronomers during the
19th century.

It must have been around for longer, but not recorded, because the meteors
it spawns have been witnessed for more than a millennium. It happens that
this particular comet has a trajectory bringing it extremely close to the
terrestrial orbit. We know that the large solid lump in its centre will not
hit our planet any time soon, but we are certain that pieces of it will
regularly cascade into the upper atmosphere.

Each time a comet returns and traverses the Earth's orbit, it is heated
sufficiently by solar radiation to make a thin layer of its surface,
predominantly made of ice, evaporate into space. This produces a cloud of
vapour, plus the characteristic tail, which both reflect a great deal of
sunlight, making comets relatively easy to discover.

As that water vapour expands, it carries with it myriad small solid lumps of
rock, and these meteoroids tend to follow much the same orbit around the sun
as the parent comet. Therefore, although comet Tempel-Tuttle passed by a
couple a years ago and can only be seen now with
a powerful telescope, the Earth is still passing through clumps of trailing

In fact, it is even possible to calculate when distinct clumps must have
been released, and precisely when they should intersect the Earth. For
example, the time on Sunday when meteoroids liberated by the comet way back
in 1767 will arrive is known fairly accurately. Four separate
groups of astronomers have done the calculations, and agree that within a
few minutes of 10:00 (Universal Time) many thousands of meteoroids that have
spent the past 234 years winging through space will end their lives in fiery
oblivion as they enter the upper atmosphere. Unfortunately that's daytime in

Similarly, two other major groups of meteoroids are expected: one cluster
jettisoned by the comet in 1699 and another relatively youthful bunch,
released in 1866. In both cases the constellation from which the meteors
appear to emanate -- Leo, hence their name -- will still be far below the
horizon, and so not visible from Europe.

This is why meteor enthusiasts are flying either east or west. One choice is
the East Coast of the US, when it will still be dark with Leo high in the
sky. Another is the Far East (ie, Japan or Australia), because the two
outbursts occur at about 3am local time on November 19.

Not all the astronomers agree, however. Peter Brown, a Canadian meteor
researcher, expects the greatest activity to come from a trail of debris
shed by the comet in 1799, with heightened meteor rates occurring over
several hours during November 18, giving viewers in the eastern Pacific
region the best opportunity.

Neither do the teams agree on how many meteors to expect. David Asher, who
works at the Armagh Observatory in Northern Ireland, is cagey on precise
numbers, but thinks that the youngest meteoroids, from 1866, will produce a
peak rate of up to 8,000 per hour. He is in Japan
already, waiting to see whether his computer modelling is correct.

By contrast, Peter Jenniskens of NASA-Ames Research Centre anticipates the
peak due to the 1767 trail to be highest of all, maximising at 4,000 per
hour. Certainly a phenomenal sight, if it turns out that way, although
nowhere near the estimate of over 100,000 per hour reported in 1966.

This year's possibilities are aided by Sunday's slender crescent moon,
leaving the sky dark enough. If the predictions are correct, then in Europe
we will not see anything extraordinary, although it might be worthwhile
having a look yourself, just in case. Look up into the sky
generally toward the north-east, where Leo will rise in the early hours.
Meteors in the shower will then appear to zip across the sky overhead. It is
entirely possible that you might see one shooting star per minute.

Calculations have already been performed for 2002, when Europe is one of the
favoured places, although one can expect them to be modified in line with
what is observed this year. The rates may be high, but the moon will flood
the sky with light.

High hopes, then, for a celestial spectacle on Sunday, even if we only see
it on the TV news. We must also hope for no damage, especially to the
International Space Station. In 1993 the European Space Agency lost a
satellite during a meteor outburst: $250 million worth of hardware wiped out
by a tiny fleck of cometary dust. Come Monday, a satellite roll call showing
all present and correct would be good news indeed.

[Duncan Steel teaches astronomy and space subjects at the University of

Guardian Newspapers Limited 2001


>From Ron Baalke <>

More Asteroids Pair Up
Astronomers have found four more binary asteroid systems.
by Vanessa Thomas
November 10, 2001

October was a busy month for binary asteroid observers. Four teams using
various observation methods found that four asteroids, once thought
solitary, all have traveling companions.

The four asteroid pairs reside throughout the solar system - from Earth's
neighborhood to the Kuiper belt.

617 Patroclus

On October 29, a team led by William Merline of the Southwest Research
Institute announced that asteroid 617 Patroclus is the first known Trojan
binary. Discovered in 1906, Patroclus shares Jupiter's nearly 12-year trip
around the sun, following 57 degrees (or about one-sixth of Jupiter's orbit)
behind the giant planet. When Merline and his team observed Patroclus with
the 8.1-meter Gemini North Telescope on September 22, they found that there
were two near-equal objects in their field of view.

Astronomers, assuming that Patroclus was a single body, had estimated that
the asteroid was 141 kilometers across. "To get the same brightness with two
objects of equal size, they would be about 100 km diameter each," Merline
explains. However, one component is slightly (0.2 magnitude) brighter than
the other, so Merline imagines the partners' sizes differ by about 10 km.

2001 QT297

While conducting follow-up observations of objects discovered by the Deep
Ecliptic Survey Team, astronomers aimed the Magellan Project's 6.5-meter
Baade Telescope at Kuiper belt object 2001 QT297. Images taken October 11
and 12 show the object attended by a fainter companion. Additional Magellan
observations last week confirm the two bodies are bound by gravity and
didn't just happen to be near one another in mid-October.

The smaller component is 0.55 magnitude fainter than the primary. Because
2001 QT297 is quite distant (about 44.5 astronomical units) and astronomers
don't know each object's albedo, it's difficult to estimate their sizes.
According to MIT astronomer Jim Elliot, who reported the discovery, the
larger component is likely between 150 and 350 km across. "If they have the
same albedo, the diameter of the larger one would be 1.3 times that of the
smaller one," he writes.

1998 ST27

Closer to home, near-Earth asteroid 1998 ST27 also appears to have a smaller
companion. A team led by Lance Benner of the Jet Propulsion Laboratory used
the world's largest single-dish telescope to observe the asteroid in early
October. According to Benner, the team's best preliminary estimate from the
Arecibo radar observations places the primary's diameter between 500 and 600
meters and the secondary's under 100 m.

The fourth binary detected with radar since September last year, 1998 ST27
was no longer observable from Arecibo after October 11. Subsequent optical
images have so far failed to resolve the two components, but Benner's team
is confident of the discovery, having imaged the separated pair over several
days. "The binary nature of 1998 ST27 is unambiguous from the Arecibo images
... because we see the two objects separated by several kilometers and we
see their positions changing with time," Benner explained.

2001 SL9

The latest binary announcement also concerned a near-Earth object.
Astronomers at the Ondrejov Observatory and in Colorado observed the
Apollo-type asteroid 2001 SL9 between October 11 and 21. They found that the
minor planet's light curve was composed of two periods: one lasting about
2.4 hours and the other about 16.4 hours.

The astronomers believe that the roughly 2-hour cycle reveals the rotational
period of 2001 SL9 and that a smaller companion orbits the asteroid
approximately every 16 hours. Two sharp dips in the light curve are probably
occultation events, they say. Assuming the components have albedos typical
of near-Earth asteroids, team leader Petr Pravec estimates that the primary
is about 1 km wide while the secondary is likely near 0.3 km across. As of
November 6, efforts to confirm 2001 SL9's binary nature had been thwarted by
clouds, but Pravec was optimistic that later attempts would have better


Chen CH, Jura M: A possible massive asteroid belt around zeta Leporis
ASTROPHYSICAL JOURNAL 560 (2): L171-L174, Part 2 OCT 20 2001

We have used the Keck I telescope to image at 11.7 and 17.9 mum the dust
emission around zeta Leporis, a main-sequence A-type star at 21.5 pc from
the Sun with an infrared excess. The excess is at most marginally resolved
at 17.9 mum. The dust distance from the star is probably less than or equal
to6 AU, although some dust may extend to 9 AU. The mass of observed dust is
similar to 10(22) g. Since the lifetime of dust particles is about 10(4) yr
because of the Poynting-Robertson effect, we robustly estimate at least 4 x
10(26) g must reside in parent bodies, which may be asteroids if the system
is in a steady state and has an age of similar to 300 Myr. This mass is
approximately 200 times that contained within the main asteroid belt in our
solar system.

Chen CH, Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095
Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA

Copyright 2001 Institute for Scientific Information


The rates of accretion, core formation and volatile loss in the early Solar
Halliday AN, Lee DC, Porcelli D, Wiechert U, Schonbachler M, Rehkamper M
15 2001

Nuclides with half-lives of 10(5)-10(8) yr permit the elucidation of nebula
time-scales and the rates of accretion of planetesimals. However, the
Hf-182-W-182 system with a half-life of 9 +/-2 Myr also provides new and
very useful constraints on the formation of the terrestrial planets. This
technique allows one to address the timing of metal-silicate equilibration
in objects as different as chondrites and the Earth. With improvements in
sensitivity and precision, very small time differences in metal segregation
in asteroids should be resolvable from measuring iron meteorites. It is
already clear that the formation and differentiation of some
asteroidal-sized objects was completed in less than 10 Myr. Accretion and
core formation were protracted in the case of the Earth (greater than 50
Myr) relative to Mars (probably less than 20 Myr). Indeed, the Martian
mantle appears to retain both chemical and isotopic heterogeneities that are
residual from the process of core formation. Such early features appear to
have been eliminated from the Earth's mantle presumably because of 4.5 Gyr
of relatively efficient convective mixing. Tungsten isotope data provide
compelling support for the 'giant impact' theory of lunar origin. The Moon
is a high Hf/W object that contains a major component of chondritic W. This
is consistent with a time of formation of greater than 50 Myr after the
start of the Solar System. New highly precise oxygen isotope data are unable
to resolve any difference between the source of components in the Earth and
Moon. Therefore, the giant impact itself may have produced some of the
differences in moderately volatile element budgets between these objects.
This finds support in precise Sr isotopic data for early lunar samples. The
data are consistent with the proto-Earth and Theia (the impactor) having
Rb/Sr ratios that were not very different from that of present day Mars.
Therefore, the extended history of accretion, rather than nebular phenomena,
may be responsible for some of the major differences between the terrestrial

Halliday AN, ETH Zentrum, Dept Earth Sci, Sonneggstr 5, CH-8092 Zurich,
ETH Zentrum, Dept Earth Sci, CH-8092 Zurich, Switzerland

Copyright 2001 Institute for Scientific Information


Sukhanov AA, Durao O, Lazzaro D: Low-cost main-belt asteroid sample return

A main-belt asteroid sample return without landing on the asteroid is
proposed. The spacecraft collects the sample during the asteroid flyby,
crossing the dust cloud produced by a projectile, and delivers the sample to
the Earth. To lower the launch energy, the spacecraft uses a Venus and Earth
gravity assist trajectory type maneuver. Five launch windows in the
2004-2010 period are considered, offering several mission options, with the
respective results of the trajectory design. Most mission options offer
other asteroid encounters in addition to the primary target. On completion
of the primary sample return mission, the spacecraft can swing by the Furth
to fly by additional asteroids or a comet. Secondary targets and possible
mission extensions are considered for some of the mission options.
Spacecraft navigation and the projectile targeting are also discussed, as
well as estimates of the mass of the sample to be collected. The sample
ejection considers two projectile types: passive, using only the impact
energy, and active, carrying an explosive inside.

Sukhanov AA, Natl Space Res Inst, Space Mech & Control Div, BR-1221040 Sao
Jose Dos Campos, Brazil
Russian Acad Sci, Flight Dynam & Data Proc Div, Space Res Inst, Moscow
117997, Russia
Natl Space Res Inst, Space Mech & Control Div, BR-1221040 Sao Jose Dos
Campos, Brazil
Natl Observ, Dept Astrophys, BR-20921400 Rio De Janeiro, Brazil

Copyright 2001 Institute for Scientific Information


Ross M, Park SY, Porter SDV: Gravitational effects of Earth in optimizing
Delta V for deflecting Earth-crossing asteroids. JOURNAL OF SPACECRAFT AND
ROCKETS  38 (5): 759-764 SEP-OCT 2001

Analyses incorporating the gravitational effects of Earth to calculate
optimal impulses for deflecting Earth-crossing asteroids are presented. The
patched conic method is used to formulate the constrained optimization
problem. Geocentric constraints are mapped to heliocentric variables by the
use of the impact parameter. The result is a unified nonlinear programming
problem in the sense that no distinctions are made for short or long warning
times. Numerical solutions indicate that the DeltaV requirements are
considerably more than those of the previously published two-body analysis
that excluded third-body effects. Generally speaking, the increments in the
minimum DeltaV due to the gravitational effects of the Earth are large (by
as much as 60%) for near-Earth asteroids, and the errors diminish for orbits
with large eccentricities (e > 0.7). Some interesting results for short
warning times are also discussed.

Ross M, Charles Stark Draper Lab Inc, Cambridge, MA 02139 USA
USN, Postgrad Sch, Dept Aeronaut & Astronaut, Monterey, CA 93943 USA

Copyright 2001 Institute for Scientific Information


Nolan MC, Asphaug E, Greenberg R, Melosh HJ: Impacts on asteroids:
Fragmentation, regolith transport, and disruption. ICARUS 153 (1): 1-15 SEP

We use a numerical hydrocode model to examine the outcomes of various size
impacts into targets the sizes of Asteroids 951 Gaspra and 243 Ida, which
were imaged by the Galileo spacecraft. A shock wave fractures the asteroid
in advance of crater excavation flow; thus, for impactors larger than 100 m
impacting at 5.3 km s(-1), tensile strength is unimportant in these bodies,
whether they are initially intact or are "rubble piles." Because of the
shock-induced fracture, impact results are controlled by gravity. Therefore
these asteroids are much more resistant to catastrophic disruption than
predicted by previous estimates, which had assumed that strength was
controlling these processes for rock targets. The rubble and regolith
produced by this fracture can be "jolted" by the impact, redistributing
surface material and globally erasing craters. The crater ejecta can produce
tens of meters of regolith per large event, likely consisting of 100-m-size
boulders mixed with smaller particles. The response of kilometer-size
asteroids to impacts is qualitatively different from that of few-centimeter
targets in terrestrial experiments, making prediction based on such
experiments difficult. The compositional distribution of delivered
meteorites depends on the outcomes of such asteroid impacts. (C) 2001
Academic Press.

Nolan MC, Natl Astron & Ionosphere Ctr, HC3 Box 53995, Arecibo, PR 00612 USA
Natl Astron & Ionosphere Ctr, Arecibo, PR 00612 USA
Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95060 USA
Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA

Copyright 2001 Institute for Scientific Information


Dell'Oro A, Paolicchi P, Cellino A, Zappala V, Tanga P, Michel P: The role
of families in determining collision probability in the asteroid main belt.
ICARUS. 153 (1): 52-60 SEP 2001

Asteroid families represent the outcomes of major collisional events in the
asteroid Main Belt. These events produced in some cases huge numbers of
fragments, down to sizes of at least I km in diameter. In this paper we show
that these families produce a significant increase in the "local" collision
rate by as much as an order of magnitude relative to the average collision
rate of the entire Belt. This fact should be taken into account in future
studies of the collisional evolution of the Main Belt. (C) 2001 Academic

Paolicchi P, Univ Pisa, Dipartimento Fis, I-51627 Pisa, Italy
Univ Pisa, Dipartimento Fis, I-51627 Pisa, Italy
Osserv Astron Torino, I-10025 Pino Torinese, TO, Italy
Observ Cote Azur, F-06304 Nice, France

Copyright 2001 Institute for Scientific Information


D'Abramo G, Harris AW, Boattini A, Werner SC, Harris AW, Valsecchi GB: A
simple probabilistic model to estimate the population of near-Earth
asteroids. ICARUS 153 (1): 214-217 SEP 2001

A simple probabilistic model for estimating the population of near-Earth
asteroids (NEAs) by comparing the rate of redetections of previously known
asteroids of a given size with new detections during a test interval of time
is described. We apply this method to the whole sample of NEA observations
(discovery observations and observations from apparitions of previously
known asteroids) made by the Lincoln near-Earth Asteroids Research Project
within the period Jan. 1, 1999-Dec. 31, 2000 and published by the Minor
Planet Center. The numbers of discoveries and redetections are sufficient to
estimate the total population in the absolute magnitude range 13.5 < H less
than or equal to 20.0. By this method we obtain an estimate of the number of
NEAs of H less than or equal to 18.0 (diameter greater than or equal to 1
km) of 855 +/- 101. We note, however, that the expected biases of this
method all work in the direction of underestimating the true population;
thus our estimate is consistent with other recent estimates, for example, W.
F. Bottke et al (2000, Science 288,2190-2194), who obtain 910 +/- 110. 2001
Academic Press.

D'Abramo G, CNR, IAS Planetol, Area Ric, Via Fosso Cavaliere 100, I-00133
Rome, Italy
CNR, IAS Planetol, Area Ric, I-00133 Rome, Italy
CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA
Osserv Astron Roma, I-00136 Rome, Italy
DLR, Ins Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany

Copyright 2001 Institute for Scientific Information


Szoor G, Elekes Z, Rozsa P, Uzonyi I, Simulak J, Kiss AZ: Magnetic
spherules: Cosmic dust or markers of a meteoritic impact?

Magnetic spherules from several localities in Hungary were analyzed and the
results were compared to analytical data of similar objects found in Japan,
Slovakia and Hawaii. The studies were carried out using micro-PIXE
technique. On the basis of morphological features and elemental compositions
it was concluded that signs of a new meteoritic impact could be found. (C)
2001 Elsevier Science B.V. All rights reserved.

Elekes Z, Hungarian Acad Sci, Inst Nucl Res, ATOMKI, Bem Ter 18-C,POB 51,
H-4001 Debrecen, Hungary
Hungarian Acad Sci, Inst Nucl Res, ATOMKI, H-4001 Debrecen, Hungary
Debrecen Univ Med, Dept Geol & Mineral, H-4010 Debrecen, Hungary

Copyright 2001 Institute for Scientific Information


McNeil WJ, Dressler RA, Murad E: Impact of a major meteor storm on Earth's
106 (A6): 10447-10465 JUN 1 2001

A comprehensive model of the effect of a major meteor storm on Earth's
ionosphere is presented. The model includes meteor stream mass distributions
based on visual magnitude observations, a differential ablation model of
major meteoric metals, Fe and Mg, and state-of-the-art modeling of the
chemistry and transport of meteoric metal atoms and ions subsequent to
deposition. Particular attention is paid to the possibility of direct ionic
deposition of metallic species. The model is validated by calculating the
effect of annual meteor showers on the background metal atom and ion
abundances. A metallic ion density increase of up to 1 order of magnitude is
observed, in agreement with in situ measurements during showers. The model
is exercised for a hypothetical Leonid meteor storm of the magnitude
reported in 1966. The model predicts the formation of a layer of metal ions
in the ionospheric E region that reaches peak densities of around 1 x 10(5)
cm(-3), corresponding to a 2 order of magnitude increase of the quiescent
nighttime E region density. Although sporadic E layers reaching or exceeding
this density are relatively common, the effect is different in that it
persists on the order of days and would be observed over nearly one-half the
globe. The model predictions are consistent with the available 1966 Leonid
storm data. In particular, the observation of enhanced, predawn sporadic E
activity points to efficient collisional ionization of meteoric metals, as
assumed in the model.

McNeil WJ, Radex Inc, 3 Preston Court, Bedford, MA 01730 USA
Radex Inc, Bedford, MA 01730 USA
USAF, Res Lab, Space Vehicles Directorate, Hanscom AFB, MA 01731 USA

Copyright 2001 Institute for Scientific Information


Malhotra R, Holman M, Ito T: Chaos and stability of the solar system
98 (22): 12342-12343 OCT 23 2001

Over the last two decades, there has come about a recognition that chaotic
dynamics is pervasive in the solar system. We now understand that the orbits
of small members of the solar system-asteroids, comets, and interplanetary
dust-are chaotic and undergo large changes on geological time scales. Are
the major planets' orbits also chaotic? The answer is not straightforward,
and the subtleties have prompted new questions.

Malhotra R, Univ Arizona, Tucson, AZ 85721 USA
Univ Arizona, Tucson, AZ 85721 USA
Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
Natl Astron Observ, Tokyo 181, Japan

Copyright 2001 Institute for Scientific Information


>From Yahoo! News, 15 November 2001

Oceans Temps, Solar Cycles Linked
By PAUL RECER, AP Science Writer

WASHINGTON (AP) - The brightening and dimming of the sun may account for a
1,500-year cycle of cooling and warming on parts of the Earth, a study of
ice in the North Atlantic suggests.

Researchers found that a very slight difference in the amount of solar
energy reaching the Earth can have a powerful chilling effect on the
climate: ice builds up in lands bordering the North Atlantic, the average
temperature drops in Europe and North America.

``Whether the whole Earth is affected, we don't know for sure yet, but it is
certainly implied,'' said Gerard C. Bond, a researcher at the Lamont-Doherty
Earth Observatory of Columbia University in Palisades, N.Y.

``The effect does extend from the high northern latitudes down, maybe even
to the tropics,'' said Bond, first author of a study appearing Friday in the
journal Science.

The cycle of sunlight intensity roughly follows a 1,500-year pattern, based
on analysis of the past 12,000 years. But the difference from the top of the
cycle to the bottom is very small, with less than a 0.1 percent difference
in energy levels, he said.

Bond and his colleagues believe this is enough to trigger severe climate
changes, such as the Little Ice Age, a 490-year period starting in 1400 that
dramatically chilled Europe and the North Atlantic.

``The climate system is extremely sensitive to weak forces, such as solar
variability,'' Bond said. ``That should make us that much more worried about
greenhouse warming.''

Greenhouse warming is thought to be caused by an increase in the atmosphere
of carbon dioxide from the burning of fossil fuels, including oil, gas and

The study is an effort to determine if small changes in sunlight over
centuries can cause the Earth's climate to warm or cool. Other experts
working on the same problem said Bond and his team have made a strong case.

``It shows that the connection is real,'' Jeffrey Park of Yale University
said in Science. To David Thomson of Queen's University in Ontario, Canada,
it seems like ``a fairly convincing case.''

Bond and his colleagues analyzed small bits of rock that were dropped to the
Atlantic floor after being carried to sea by icebergs that broke off
glaciers in Iceland and other northern islands.

The rocks fell as the icebergs melted, Bond said. Thus, the farther south
the rocks fell, the farther south the icebergs drifted, providing a measure
of ocean temperature.

To determine when the rocks were dropped, researchers dated the age of
shells deposited at the same time and place.

The 1,500-year cycle of warming and cooling corresponds to data from tree
ring studies, another way of measuring the sun's strength over time.

Bond said the sun, at its most energetic, strengthens the Earth's magnetic
field, which blocks more cosmic rays, a type of radiation streaking in from
deep space.

When cosmic rays hit plants, they cause the formation of certain isotopes,
such as carbon-14, that can be measured in ancient tree rings. A tree ring
rich in carbon-14 suggests an inactive sun, for example.

Measurements of the iceberg drift and the tree rings showed a similar cycle,
Bond said.

``The connection we observed is that the increases in icebergs and drift ice
occur at the same times as the increase in (carbon-14), which means the sun
was weaker,'' said Bond.

He said the findings also agree with studies that measured the chilling of
the Earth based on the advance and retreat of alpine glaciers in Europe.

Bond said the Earth's temperature is still recovering from the Little Ice
Age, when ocean temperatures dropped by two to three degrees. That change
was enough for ice to jam most of the North Atlantic, closing many ports in
the winter and affecting the weather throughout Europe. Rivers that never
freeze in modern times were routinely used then for ice skating, Bond said.

Based on the 1,500-year cycle, Bond said that the Earth's next little ice
age could occur about the year 3100, plus or minus 500 years.

Copyright 2001, Yahoo News


>From Harvey Leifert <>

Joint Release:
American Geophysical Union/Columbia University

November 15, 2001
AGU Release No. 01-28
For Immediate Release

AGU Contact: Harvey Leifert
(202) 777-7507

Columbia Earth Institute Contact:
Abigail Beshkin
(917) 553-5579

Damage to Buildings Near World Trade Center Towers Caused by Falling Debris
and Air Pressure Wave, Not Ground Shaking, Seismologists Report

WASHINGTON - On September 11, seismographs operated by Columbia University's
Lamont-Doherty Earth Observatory in Palisades, New York, recorded seismic
signals produced by the impacts of the two aircraft hitting the Twin Towers
of the World Trade Center and the subsequent collapse of the 110 story
towers. While the ground shaking was consistent with the energy released by
small earthquakes, it was not sufficient to cause the collapse of, or damage
to, surrounding buildings, as some have thought. Rather, seismologists
report, the buildings around the Twin towers were impacted both by the
kinetic energy of the falling debris and by the pressure exerted on them by
a dust- and particle-laden blast produced by the collapse.

Writing in the November 20 issue of Eos, published by the American
Geophysical Union, seismologists from Lamont-Doherty outline the sequence of
seismographic recordings from that tragic day. They argue that vibrations
recorded on September 11 were of a magnitude believed too low to cause
structural damage to buildings, especially in the northeastern United

The authors add, however, that because there were no seismographic stations
in or even near the World Trade Center, it is impossible to know for sure
that the ground-shaking had no effect on neighboring buildings. Ultimately,
they say, officials should consider the importance of placing seismographic
stations in high density urban areas.

"Our recordings were made at considerable distance," says Won-Young Kim, who
is in charge of seismological network operations for Lamont-Doherty.
"However, plans are pending for an Advanced National Seismic System [ANSS]
that calls for placing seismic instruments in such urban areas as New York
City," he said. "The tragic events of September 11 show that such
instrumentation can serve a purpose that sometimes transcends strict
earthquake applications."

The Eos paper was written by 12 researchers at Lamont, including Kim, Lynn
Sykes, Klaus Jacob, Paul Richards, and Arthur Lerner-Lam, director of
Columbia's new Center for Hazards and Risk Research. Lerner-Lam explained
what happened once the planes hit the World Trade Center and why they
resulted in relatively small seismographic readings.

"The energy contained in the amount of fuel combusted was equivalent to the
energy released by 240 tons of TNT," said Lerner-Lam. "This energy was
absorbed by the buildings and produced the observed fireballs, but did not
immediately cause the collapse. During the collapse, most of the energy of
the falling debris was absorbed by the towers and the neighboring
structures, converting them into rubble and dust or causing other damagebut
not causing significant ground shaking."

Seismographic recordings of the WTC tower collapses were made in five
states, as far away as 428 kilometers [266 miles] in Lisbon, New Hampshire.
Lamont's home station, in Palisades, New York, is located above the Hudson
River, 34 kilometers [21 miles] from downtown Manhattan, where the towers

The aircraft impacts registered local magnitude (ML) 0.9 and 0.7, indicating
minimal earth shaking as a result. The subsequent collapsing of the towers,
on the contrary, registered magnitudes of 2.1 and 2.3, comparable to the
small earthquake that had occurred beneath the east side of Manhattan on
January 17, 2001. The Lamont seismographs established the following

8:46:26 a.m. EDT [1240 UTC] - Aircraft impact - north tower - Magnitude 0.9
9:02:54 a.m. EDT [1302 UTC] - Aircraft impact - south tower - Magnitude 0.7
9:59:04 a.m. EDT [1359 UTC] - Collapse - south tower - Magnitude 2.1
10:28:31 a.m. EDT [1428 UTC] - Collapse - north tower - Magnitude 2.3

In addition, the seismic waves were short-period surface waves, traveling
within the upper few kilometers [miles] of the Earth's crust. They were
caused by the interaction between the ground and the building foundations,
which transmitted the energy from the impacts and collapses.

The authors also noted that, as seen in television images, the fall of the
towers was similar to a pyroclastic flow down a volcano, where hot dust and
chunks of material descend at high temperatures. The collapse of the WTC
generated such a flow, though without the high temperatures.

The Lamont-Doherty Earth Observatory operates 34 seismographic stations in
the northeast in collaboration with several institutions. Network operations
are supported by the United States Geological Survey. The network is part of
the Advanced National Seismic System, a national seismological monitoring
initiative being implemented through a USGS-university partnership.

Notes for journalists:

The paper by Won-Young Kim, Lynn R. Sykes, J.H. Armitage, J.K. Xie, Klaus H.
Jacob, Paul G. Richards, M. West, F. Waldhauser, J. Armbruster, L. Seeber,
W.X. Du, and Arthur Lerner-Lam, "Seismic Waves Generated by Aircraft Impacts
and Building Collapses at World Trade Center, New York City" appears in Eos,
Volume 82, number 47 (20 November 2001), page 565.

Journalists may request a copy of the paper from Harvey Leifert,, specifying a pdf or fax version. Please include your name,
publication, postal address, phone, fax, and email address. There is no

Dr. Arthur Lerner-Lam may be contacted at +1 (845) 359-2900 extension 356,



>From Christian Koeberl <>

Hi Benny,

I was away on travel and saw your note on the possible crater in Iraq -
highly speculative, nobody knows that it really is a crater.

Below is a link to a more cautious news release from Wits University on that

Maybe you want to alert the CCNet to this.

Regards, Christian
Christian Koeberl
Institute of Geochemistry
University of Vienna
Althanstrasse 14
A-1090 Vienna, AUSTRIA

Tel.: +43-1-4277-53110
Fax: +43-1-4277-9531


A new crater-like structure has been discovered on satellite images of the
Al Amarah marshes in southern Iraq by Wits geologist Dr Sharad Master.

The structure is a circular, slightly polygonal feature about 3.4 km in
diameter, with a raised rim and a surrounding annulus, which is about 500
metres wide. Because it is found in very young alluvial sediments near the
confluence of the Tigris and Euphrates rivers, the structure must have
formed in the last 6 000 years.

Master regards the structure as a possible meteorite impact crater, in a
paper presented in September at the Meteoritical Society meeting at the
Vatican City.

Master, in an abstract in Meteoritics and Planetary Science, also speculated
on a possible link between this structure, if it turns out to be in impact
crater, and the account of the Flood in the Epic of Gilgamesh, which dates
from the end of the 3rd millennium BC. Now other scientists, including
archaeologists and astronomers, have seized on this discovery to explain the
puzzling demise of a number of Bronze Age sites in the Ancient Near East
around 2 300 BC.

Master, of the Impact Cratering Research Group in the School of Geosciences,
stressed that the crater has not yet been investigated on the ground, and
its impact origin has not been proven. Its age is also uncertain, except
that it is probably less than 6 000 years old. Because of the important
implications for the demise of ancient civilizations and cultures of this
crater, if it is indeed of impact origin, it is imperative that a ground
investigation of the structure be made, so that its age and origin can be
ascertained. Until a thorough investigation is made of the structure, any
speculations about its possible role in ancient history will remain just

>From Duncan A. Lunan <>

Dear Benny,

Many thanks for the special report. When I was researching "Man and the
Stars" in 1972-73, I followed up a classic article on impacts by Isaac
Asimov called 'The Rocks of Damocles', in which he suggested that the
Biblical flood legend was a memory of an impact.   What I found, from
Pritchard's "Ancient Near Eastern Myths Relating to the Old Testament", was
the Gilgamesh account of the Flood as given in the articles you've
reproduced. In the most ancient version, c. 2250 BC, there is indeed what
appears to be a heat flash, ground shock, mushroom cloud, blast wave and
tsunami, followed by the sky clouding over and torrential rain.
(There is also the extraordinary passage in which the Noah precursor,
Utanapishtim, is warned by the god Ea of what's to come by way of talking
wall. "After the flood, we shall return the people to their settlements".
Here Pritchard adds in a footnote that this obviously must be the correct
translation, to correspond with the Bible, but honesty compels him to note
that the word 'after' actually reads 'before', 'return' actually reads
'withdraw', and 'to' actually reads 'from'.   "Before the flood, we shall
withdraw the people from their settlements" - an evacuation, in advance of a
foreseen natural catastrophe, and not a divine punishment at all).

But the related accounts from other cultures were even more striking
(literally). The Egyptian Coptic account has the Flood preceded by fire from
the constellation Leo, while invisible divine personages stalked Egypt
striking down the populace with iron maces - meteorite fragments or
secondaries? The Hittite legend, from the mountains, says the Flood was
caused by the Moon falling to Earth - another visual sighting? The Indian
Sanskrit version doesn't mention impact but has many other details in
common, including other versions of the Sumerian characters and the same
statement that the sea invaded the land BEFORE the torrential rain. Even the
Biblical account says the same, as Asimov pointed out:  after the cloud on
the horizon "no bigger than a man's hand" (mushroom?), then "the fountains
of the deep were unloosed, and THEN the heavens opened", in that order. The
Chinese account is the most fantastical, but character names are
recognisable even there, and it says the Flood was caused by a demon who
butted one of the supporting pillars of the world.
Of course, when I pointed this out nearly thirty years ago, I was told I was
worse than von Daniken. It's nice to know I wasn't as daft as all that!
Best wishes,
Duncan Lunan.

>From Hermann Burchard <>

Dear Benny,

Professor Andy Gale's exciting discovery that only 17% of dinosaurs went
extinct at the K/T boundary 65 Ma ago promises new fossils from those 83%
survivors to be found soon in Paleocene and perhaps Eocene strata.


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