CCNet 25/2002 - 18 February 2002

"The possibility that a comet or asteroid might come crashing down
out of the sky is unlikely."
--Anthony Ramirez, The New York Times, 17 February 2002

"Clearly not all is well as a result of Spaceguard."
--Ivan Bekey, 18 February 2002

"If Congress won't fund [NEO searches], I'll be assembling a group
of private individuals who will. I really like this project because it's
one of the few things I can donate to that can literally "save the world."
--Steve Kirsch, Kirsch Foundation

    The New York Times, 17 February 2002

    Daniel Fischer <>

    Kirsch Foundation

    National Geographic News, 15 February 2002

    Andrew Yee <>

    Ivan Bekey <>

    Mark Boslough <>

    Alastair McBeath <>

    Duncan Steel <>

     Hermann Burchard <>

     Andrew Yee <>


>From The New York Times, 17 February 2002

At this moment, an asteroid two-thirds the length of the Titanic with the
utilitarian name 2002 AT4 is barreling toward Earth. Fortunately, AT4,
traveling at 14,000 miles an hour, will miss the planet by nearly six
million miles. That's a close shave (sic) in astronomical terms, but still
25 times the distance between Earth and the Moon.

On Jan. 7, Asteroid 2001 YB5 passed far closer, about twice the distance to
the Moon. What's more, scientists spotted it only two weeks earlier because
it had been so small and faint against the night sky.

YB5 was two-thirds the height of the Empire State Building. If it had hit
the Pacific Ocean, the splash would have sent a tsunami 30 feet high
crashing into San Francisco. If the asteroid had hit land, the impact would
have equaled 350,0000 Hiroshima atomic bombs and caused incalculable

The possibility that a comet or asteroid might come crashing down out of the
sky is unlikely (sic). But scientists, who have been spotting and tracking
asteroids and comets in earnest for the last 30 years, have been worrying
about them even longer. After all, the extinction of the dinosaurs 65
million years ago is thought to have been caused by the sudden onset of an
ice age (sic) brought on by a meteor colliding with Earth.

In recognition of this exotic threat, NASA began its Near-Earth Object
Program in 1998 to catalog what are called "potentially hazardous
asteroids." A related NASA program, Deep Impact, will send a robot
spacecraft a bit beyond the orbit of Mars in 2005 to learn the composition
of a comet. The mission is primarily scientific, but data might also help
scientists deflect a comet should one ever threaten Earth.

Comets are kissing cousins to asteroids. "If you look in your telescope and
you see fuzz around it, it's a comet," Michael F. A'Hearn, a University of
Maryland astronomy professor and principal investigator for Deep Impact,
said wryly. "If you don't, it's an asteroid."

Comets are probably - but no one yet knows - porous, like snow mixed with
sand and dirt. Asteroids are probably solid, like sand or rock, or some
combination. But some asteroids may be in-between and watery, and may look
like a somewhat-dry comet.

Asteroids have small orbital periods only several times larger than the
period of Earth, which, of course, lasts a year. Asteroids also cluster in a
few places, typically between Mars, the fourth planet, and Jupiter, the
fifth. Many comets, on the other hand, range far outside the solar system
and have orbits measured in decades or more.

But whatever they are, neither is simply a bullet fired at the biosphere by
some cosmic Dirty Harry. In fact, asteroid showers and comet collisions may
have promoted life on Earth by depositing carbon-based materials and water.
Comets may also be a kind of time machine, which collect in their ice the
long-ago minerals and gases of the ancient solar system.

Relatively little is known about comets, which make up only 3 percent of
near-Earth objects, hence the July 4, 2005, rendezvous between Deep Impact
and a good-size comet, Tempel 1, about 60 city blocks in diameter. The
plan's key is something called the Impactor, a copper and aluminum device
that, at 770 pounds, resembles an enormous pasta pot.

The rocket-propelled Impactor will separate from a fly-by craft and crash
into Tempel 1. The bigger the resulting crater, the more likely the comet is
made up of ice and dirt. The smaller the crater, the more likely the comet
is made up of more solid materials.

Such basic information could be important in learning how to fend off a
rogue comet, Dr. A'Hearn said. Blowing apart a solid-rock comet, for
example, might makes matters worse by creating many smaller ones. So it
might be better to tap the comet out of Earth's way with a small bomb, or by
landing a rocket on it and firing its engine, or even setting up a sail that
would be pushed by the gentle, but still considerable, pressure of sunlight.

Meanwhile, NASA's Near-Earth Object Program - five NASA-supported telescope
laboratories scanning the skies - is designed to give Earth plenty of time
to defend itself. The asteroid that will pass closest to Earth in the next
century is called 1999 AN10. It may come within 242,000 miles, or about the
distance between Earth and the Moon.

Scientists are confident they can predict the path of 1999 AN10. An asteroid
in space is not like an arrow or a baseball on earth, whose trajectory could
be altered by a sudden rain or gust of wind. It's more like a train on a
track, said Donald K. Yeomans, manager of the Near- Earth Object Program
Office in Pasadena. The only uncertainty is when it will arrive, he said.
And Asteroid 1999 AN10 is scheduled to pass on the morning of Aug. 7, 2027
at 7:10 Coordinated Universal Time.

"We may," Dr. Yeomans said, "be off by a minute or so."
Copyright 2002 The New York Times Company

See also yesterday's humour column in the Washington Post


>From Daniel Fischer <>

Dear Benny,

a sidebar to the cover story of Newsweek (Feb. 4, 2002, international
edition, p. 37) on the Gates Foundation said in its headline that "venture
philantropists bring business models, jargon and demands to the job of
saving us all from cancer, asteroids, you name it." The asteroid reference
is to Steve Kirsch: "He set up his own foundation to benefit 'everyone,'
funding research on everything from cancer to near-earth objects. 'It's
guaranteed that we will be hit by an asteroid sometime in the future,'
perhaps 'before we end this phone conversation,' Kirsch explains. 'It would
cost several billion lives, and we can absolutely save those lives for $50
million, which is less than the cost of a private jet. I call it enlightened

According to the search tool of, Kirsch has never
been mentioned on CCNet. Checking out the Kirsch Foundation's homepage at, one learns that NEO searches are indeed one of his
favorite topics in his quest for "a safe and peaceful world, one without the
threat of destruction" and that he wants to "invest in causes where
high-impact, leverageable activities can result in a safer and healthier
world." Specifically, his "GOAL 1: ENSURE WORLD SAFETY" intends to reduce
the "chance of world destruction from two preventable sources. Strategies:

* Reduce threat from weapons of mass destruction (WMD).
* Reduce risk associated with Near Earth Objects (NEOs) of one kilometer or
greater by indentifying them."

In his "Reflections" #5 and #15 Kirsch goes to some length to explain the
problem and to measure the cost (!) of a major impact, calculating that "a
single $20 million grant saves a mathematically expected $30 billion each
year" - "I don't know anything with that kind of return on investment."
Furthermore, "if Congress won't fund it, I'll be assembling a group of
private individuals who will. I really like this project because it's one of
the few things I can donate to that can literally 'save the world.'" So far
he is supporting the Spacewatch program in Arizona (see also their
acknowledgement at with about
$100 000 per year, "until the research is complete. This money is helpful,
but it is not sufficient."

This final remark leaves me puzzled, esp. in the context of his remarks to
Newsweek that $50 million would solve the problem: Does that mean that much
larger donations than the $100 000
p.a. for Spacewatch are on the horizon? Or does he intend to trigger more
philantropic support for NEO searches? According to the Newsweek sidebar,
"there are thousands" of American entrepreneurs "with a business plan to
save the world" (in a wider sense, of course): With all the resistance in
the governments of the U.S., the UK, Germany and so on to funding a
full-blown NEO search program, one cannot but wonder whether the outreach in
the NEO community might not be more effective dollar-wise when directed
specifically towards the new "venture philantropists" instead ...

Daniel Fischer

P.S.: During the past five weeks about everyone making a public statement
about NEOs and impacts has referred to the Jan. 7 Earth flyby of 2001 YB5 as
a particularly scary 'warning shot' - and
no one seems to have noted that there was a *much* scarier 'near miss' just
a few months earlier. 2001 YB5 had a diameter of only 250 to 500 meters,
well below even the pre-Pope-ian limit for a
global catastrophy, and it approached Earth to within 833 000 km. But on
Sept. 4, 2001, asteroid 2001 WN15 came to within 634 000 km, according to - and it had a diameter of 600 to
1300 meters. Unfortunately it was discovered only 2 1/2 months later: we
wouldn't even have known what hit us ...


>From Kirsch Foundation

I wanted to provide a member of the U.S. Congress with some factual
information about the potential devastating consequences of under-funding
research to identify asteroids that could hit the Earth. Two professionals
in the field, Donald K. Yeomans, the Manager of NASA's Near-Earth Object
Office, and Robert McMillan, Associate Research Scientist and Principal
Investigator, Spacewatch, University of Arizona, wrote the following memo
and gave me permission to publicize it. After you read their memo, you will
see additional comments from me.

>From Donald K. Yeomans and Robert McMillan:

The scientific community has come to realize that the hazard to Earth from
asteroid and comet collisions is comparable to other natural disasters such
as earthquakes, volcanoes and floods, differing not in terms of "average
fatalities per year" but mainly in terms of frequency of occurrence.
Although no significant number of deaths by asteroid or comet collisions
have occurred in all of recorded history, major impact events are expected
on time scales of about 500,000 years. Impacts of these so-called Near-Earth
Objects (NEOs) have catastrophically disrupted the Earth's ecosystem in the
past. Unless checked, these disasters will occur again; the question is when
- not if. While events of this type could cause billions of fatalities from
a single strike, impacts of these so-called Near-Earth Objects (NEOs) are
avoidable. NEO impacts are the only type of serious natural disaster for
which accurate predictions can be made and for which the technology exists
for successful mitigation efforts.

Currently NASA contributes some support for five small telescopic search
groups in their efforts to discover the large NEOs that form the majority of
the impact threat to Earth. NASA's goal is to discover, within 10 years, 90%
of the population of NEOs with diameters larger than one kilometer. For this
population, predictions of their future motions can be made, future close
Earth approaches can be identified, and Earth impact probabilities computed.
While the total population of large NEOs is not accurately known, recent
modeling estimates put this total between 700 and 1000 objects. By mid-May
2000, a total of 390 of these large NEOs had been discovered and all are now
being tracked. None of these known objects pose a near-term threat to Earth.
However, most of the population remains undiscovered and the current
discovery rate is at least a factor of four too slow to achieve the NASA
discovery goal.

The annual support of Near-Earth Object research within NASA is currently
3.5 million dollars. Additional funding is required to boost the discovery
rate to reach the NASA goal and to characterize a sizable percentage of
these objects in terms of their likely sizes, structures and compositions.
Comets and asteroids in the near-Earth population are known to run the gamut
from small, fragile fluffballs to several kilometer-sized slabs of solid
iron. Successful mitigation techniques for Earth threatening objects will
require that we know not only when an Earth impact is likely but also what
is the size, structure and likely composition of the potential impactor. The
current NASA budget of $3.5 million dollars per year for NEO research must
be raised to at least twice that amount to effectively deal with the menace
of the near-Earth objects.

It should be understood clearly that this recommendation for a funding
increase is not an effort on our part to augment funding for a particular
group. The funds should continue to be awarded by NASA through its peer
review process. However, Congress should also understand that there is value
in stabilizing the funding for the existing NEO research teams with their
established talents and physical assets.


My Thoughts:

The statistics cited above are independent probabilities. That means that
the probability that we are hit next year is exactly the same as the
probability we are hit 500,000 years from now. The key point is that it is
not a question of whether we will be hit. For a small amount of money, we
will absolutely save the lives of billions of people. We just don't know
when. Since it could be next year, the time to spend this money is now. Each
dollar you spend today saves 100 lives sometime in the future. Now that's
cost effective!

Statistically, the chances of being killed by an asteroid are about 1 in
5,000, which is greater than the chance of being killed in a plane crash.
It's just that the incidences of asteroid impact are fewer and further
between. Based on these probabilities, we are seriously underfunding this
effort compared to the dollars we are spending on air safety. In fact, the
additional funding being sought here is less than the cost of a small jet.

After reading articles in Time magazine about "near miss" asteroids cited
below, I began funding Jim Scotti's research group through the Kirsch
Foundation with over $150,000 over the past 2 years. Through the Foundation,
I will continue to give $100,000 per year until the research is complete.
This money is helpful, but it is not sufficient.

Scotti was the astronomer who found XL1 in 1994; it came within 65,000 miles
of Earth. Think about how close that is. The circumference of the Earth is
around 24,000 miles so that is around 2.5 times the circumference of the
Earth. That's way too close for comfort. Because of a lack of funds, we had
only 14 hours of warning for that asteroid. And in 1996, a rock one-third of
a mile wide came within 280,000 miles. Again, a lack of funds meant we only
had four days notice. Scotti was also the astronomer who discovered XF11 in
1997. This asteroid is a mile wide and will come within 600,000 miles of
Earth in 2028. Here we have 30 years notice. Spending the money now does pay

There are less people working in this area worldwide than work at a single
McDonald's restaurant. Isn't it time for a change? Wasn't a near miss six
years ago enough time for Congress to make an appropriation? Will it take a
direct hit with six seconds of notice where billions of people have to die
for us to allocate a total dollar amount that is less than the cost of a
single commercial jetliner?


>From Kirsch Foundation

Based on current analysis, 90% of the asteroids that could devastate the
Earth have not been identified. With an extra $1M/year in funding, we could
identify all NEOs (as they are called) in ten years. Sure the chances are
really slim that we are going to be hit soon. But they aren't zero.

Although at present there is no asteroid KNOWN to be on a collision course
with Earth, the probability of an unknown asteroid larger than one kilometer
in diameter hitting in any one year is estimated by Dr. Paul Chodas of the
Jet Propulsion Laboratory (JPL) as 1 in 100,000. That makes it more likely
that you'll be hit by an asteroid next year than it is that you'll win the
lottery or be diagnosed with many deadly diseases.

The cost/benefit of such a donation is enormous. What's the value of a human
life? A New York jury recently awarded $150K to $215K each to 13 passengers
for 28 seconds of turbulence on an American Airlines flight. Clearly a whole
life must be worth a lot more than 28 seconds of inconvenience.

Let's assume a life is worth a cool $1M. There are six billion people on the
planet and we'll say that half will die shortly after impact. It won't be a
picnic for the other half who survive either, but we don't even have to go
there. So a one-time $20 million investment saves three billion lives with a
1 in 100,000 chance every year.

In other words, a single $20 million grant saves a mathematically expected
$30 billion each year. Not just the first year. But $30 billion each and
every year for the next 100,000 years. That's less than the price of one
jet. I don't know anything with that kind of return on investment.

And if we get hit without warning, it is literally "game over." One million
dollars a year seems like a small price to pay for "collision insurance."
Heck, it isn't much more than I pay for collision on my NSX. If Congress
won't fund it, I'll be assembling a group of private individuals who will. I
really like this project because it's one of the few things I can donate to
that can literally "save the world."

Of course, I think it is unlikely Congress will fund it. If we don't get
hit, Senators and Representatives will be criticized for wasting taxpayers'
money. And if we do get hit, it won't matter since we'll all probably be
dead. So politically, it's a stupid decision to vote for this since you
can't win either way.

In a recent issue, Time Magazine featured
a thought-provoking article on asteroids and their potential threat to


>From National Geographic News, 15 February 2002

Brian Handwerk

The horrors unleashed by the recent eruption of Congo's Mount Nyiragongo
have demonstrated once again our uneasy relationship with the fires that
rage below Earth's surface.

In January, tons of molten rock from Nyiragongo streamed into the city of
Goma, demolishing many of its neighborhoods and killing dozens of people. It
was a harsh reminder that, although volcanoes have been ravaging populated
areas throughout history, we still lack the ability to accurately predict
deadly eruptions and save lives.
New light might be shed on predicting volcanic eruptions based on research
conducted at the Aletotian islands. Research finds that volcanic eruptions
may be linked to changes in lunar cycles.

If predicting eruptions is a confusing puzzle, volcano hunters Steve and
Donna O'Meara believe that they may have identified a key piece. The
husband-and-wife team are investigating a connection that some volcano
watchers have noted since early times, but none has adequately studied-the
role of the moon in affecting volcanic activity.

The O'Mearas' interest in this lunar theory began by chance back in 1996,
while the duo was studying an erupting volcano in the field. Steve is an
astronomer by training, and it was his experience in this seemingly
unrelated field that led him to a fateful discovery.

While compiling detailed journals of his scientific observations, he began
to notice a correlation between increasing volcanic activity and lunar
cycles. Pouring through stacks of data he had collected over twenty years in
the field, Steve examined past eruptions and saw some of the same patterns.
Further research suggested that a lunar pattern was also apparent in some
famous historic eruptions, such as Krakatoa in 1883.

Other observers throughout history had noted the possibility of such a
connection, but always as a footnote, and always when looking back at
eruptions that had already occurred. No one had given the matter
comprehensive study, and no one had attempted to employ these lunar patterns
as one of the tools to predict future volcanic eruptions.

Stromboli, a Volcanic Hotspot

Supported by the National Geographic Society, the husband-and-wife team set
out to test just that possibility at one of Earth's volcanic hotspots, the
summit of Stromboli on Italy's Aeolian Islands.

Stromboli is one of the most active volcanoes on the planet. The restless
mountain has been in a state of nearly continuous eruption for at least
2,000 years. Although large eruptions and lava flows are uncommon, smaller
eruptions occur very frequently and often hurl blobs of lava above the
crater rim.

Stromboli's slopes can be inhospitable. Visitors have to contend with toxic
gases, noxious fumes, and showers of hot ash. While on site the team
(composed of Steve, Donna, and several research assistants) also endured
unusually brutal weather conditions at their mountaintop camp. Yet, fueled
by their enthusiasm, they carried on making observations 24 hours a day,
working in six-hour shifts. Despite the skepticism of some volcanologists,
the group was determined to put the lunar theory to the test.

Although living conditions on Stromboli left much to be desired, the climate
was ideal for research because of the continually active eruptions and the
occurrence of several important lunar events. The moon entered some
important phases during the team's time on Stromboli. In the 14-day span of
observations the moon reached perigee (the point when its orbit is nearest
the Earth) and also experienced a full moon phase. The full moon is a point
at which the moon exerts particularly great influence on the Earth, as
evidenced by high tides.

The team's task was to determine when the greatest peaks in eruption
activity occurred, and what connection the increased activity might have
with the moon's gravitational pull. Following the patterns they had seen in
the past, the O'Mearas predicted that during the volcano's ongoing
eruptions, there would be peaks in volcanic activity at perigee and at full
moon. In this case, events bore out that hypothesis and in fact the greatest
spike in volcanic activity occurred at a point in time just between full
moon and perigee.

Volcanoes Under Gravity's Law

As exciting as the O'Mearas' investigations may be, Steve cautions that they
cannot be considered independently of other volcanic variables. "We're not
saying that by simply following the moon we can predict when a volcano will
erupt," he notes. He does, however, advocate including the moon in the
equation for predicting eruptions, with other more traditional variables.

"A volcanic eruption is a chaotic event," Steve says. "In order to predict
such an event you must know all of the variables involved. Gravity is one of
Earth's strongest forces, so you can't ignore the moon. The challenge is to
find out just how it's playing a role."

On Sunday, February 17, at 8 p.m. ET/5 p.m. PT on MSNBC in the United
States, National Geographic EXPLORER joins volcano hunters Steve and Donna
O'Meara for two perilous weeks atop one of the world's most active hot
spots, Stromboli, in Italy's Aeolian Islands.

Expeditions Council

Volcano researchers Stephen and Donna O'Meara founded Volcano Watch
International to better understand Earth's active volcanoes and to help save
the lives of people living on or near dangerous volcanoes. For the last 22
years, the O'Mearas have traveled the globe, documenting volcanic eruptions
on film and video and visiting over 100 volcanoes.
Stephen and Donna O'Meara are among a group of explorers and adventurers
supported by the National Geographic Society's Expeditions Council.

Through the Expeditions Council, the National Geographic Society awards
grants to support explorations and adventures into untamed territory. In the
spirit of the Society's mission-the increase and diffusion of geographic
knowledge&151;these grants support projects that will reveal information
about areas that are largely or completely unknown. The council's scope of
exploration includes all realms of Earth, from the deepest oceans to the
highest mountains and beyond.

To date, Expeditions Council grants have ranged from marine research
projects to the documentation of vanishing rain forests, from first ascents
of mountain peaks to retracings of historic journeys, from first descents of
the world's most remote and challenging rivers to unprecedented exploration
of the worlds deepest submerged cave system.

2002 National Geographic Society. All rights reserved

>From Andrew Yee <>

News Service
Cornell University
Ithaca, New York

Contact: David Brand
Office: 607-255-3651

Why can't Johnny understand science? Question vexing researchers and
educators to be aired at AAAS session

BOSTON -- Science is part of our daily lives -- the way we understand the
natural world, the technologies we use and the decisions we make about our
health and the environment. So why, asks Cornell University researcher Bruce
Lewenstein, do most people know so little about science?

Lewenstein, who is an associate professor of science communication at
Cornell, is among the growing number of educators exploring the gap between
practitioners of science and the public at large. Aided by federal and
university funding initiatives, they are working to promote general
"scientific literacy" through community involvement and education efforts,
known as outreach. But, they ask, are their efforts working?

The question will be addressed by researchers and educators at 9 a.m. today
(Feb. 17) at a symposium, "Best Practices From Research Scientists Who
Communicate With The Public," at the American Association for the
Advancement of Science (AAAS) annual meeting. The panel is organized by
Lewenstein and by Ilan Chabay of the New Curiosity Shop, consultants in the
design of science learning experiences and programs.

In recent years, increasing emphasis on outreach and education by major
scientific funding agencies -- including the National Science Foundation
(NSF) and the National Institutes of Health -- has sparked renewed interest
among scientists in developing ways to work outreach into their research
programs. For example, the NSF, which distributes more than $4 billion in
research funding annually, in 1997 stopped evaluating grant proposals
primarily on the intellectual merit of the proposed research. Now the
standard includes broader social impacts of the research under consideration
and strengthens the role of education and the participation of
underrepresented groups. Even so, says Lewenstein, public education still
has a long way to go. "Senior people at scientific institutions and societies all
recognize the importance of outreach. Meanwhile, younger researchers are often
socialized to not engage in outreach but to stay in the lab," he says. "There are lots of
scientists who engage in outreach, but compared to the number who could,
it's pretty small."

Lewenstein edits a quarterly academic journal, Public Understanding of
Science, and directs the New York Science Education Program, a consortium of
colleges committed to improving undergraduate science education.

Also speaking on the AAAS panel will be Nevjinder Singhota, educational
programs director at the Cornell Center for Materials Research (CCMR), one
of 29 such NSF-funded centers that promotes
interdisciplinary research and education.

Singhota coordinates a diverse outreach program, one of several at Cornell
that brings science faculty, graduate students and undergraduates into area
K-12 classrooms. CCMR also runs workshops
for teachers, home-schooled children and teenagers in juvenile detention
facilities. A crucial factor in the success of CCMR outreach, according to
Singhota, is making education part of the administrative vision. She notes
that the director of CCMR, Frank DiSalvo, the John A. Newman Professor of
Physical Sciences at Cornell, and the associate director, Helene Schember,
encourage faculty to do outreach. "They themselves do it, they develop the
lessons, and so it evolved from that. It's just part of the whole process,"
she says.

During the past two years, CCMR has offered more than 40 programs reaching
more than 70 undergraduates, 2,000 K-12 students, 100 teachers, 125 parents
and 20,000 upstate New York newspaper readers through an ask-the-scientist
column. Participants have included more than 100 faculty members, 80
graduate and post doctoral students, 16 professional staff members and
numerous undergraduates.

DiSalvo sees science education as essential to a democratic society in which
the public makes decisions related to science and technology. "A
scientifically illiterate public is a recipe for disaster," he says. "As a
democracy it's in our best interest to become scientifically literate, and
that's really what outreach is about -- to introduce people to the methods
of science and the fun of science."

Related World Wide Web sites:

The following sites provide additional information on this news release.
Some might not be part of the Cornell University community, and Cornell has
no control over their content or availability.


* Public Understanding of Science

* International Network on Public Communication of Science and



>From Ivan Bekey <>

Dear Benny

I agree with your comment. In addition the Morrison statement completely
ignores long period comets, which are almost totally unpredictable, could
well be very large, and travel at such high velocities from the outer
reaches of the Solar System that detection early enough to sound a warning
even months ahead will be difficult and require a number of very large space-based
telescopes. Needless to say those telescopes do not exist today, even though
technologies for their development at reasonable cost have already been
identified. But clearly not all is well as a result of Spaceguard.

Ivan Bekey


>From Mark Boslough <>

David Morrison is right. Moreover, if a nuclear explosion is supposed to be
providing the energy that deflects the asteroid, what difference does it
make what direction the missile comes from, as long as the nuke blows up
where you need it? The momentum of the missile would be a tiny
fraction of what would be required. Otherwise, why even bother having a

Mark Boslough


>From Alastair McBeath <>

Dear Benny,

Had Ed Grondine bothered to read what I wrote in CCNet 20/2002 (8 February)
before responding in CCNet 21/2002 (12 February) and leaping to the
conclusions about what he imagined I'd written - or not written, or "meant
to" have written - that he did, it might have been worth engaging in some
meaningful discussions about the mythological and etiological aspects of the
construct that is the biblical 'Joshua', with its fascinating description of
an ancient holy war which may or may not have actually happened, and if it
did, when that might have been. Since it's clear Ed has no interest in such
discussions, I see little point in wasting my time and energy in a fruitless
exercise of this kind. And Ed, somebody really should have mentioned before
now to you that by the time you've resorted to shouting at and denigrating
anyone who appears not to share your exact point of view and personal
beliefs, you've already lost the argument.

Alastair McBeath


>From Duncan Steel <>

Dear Benny,

Thanks for running the review of my book Target Earth from the journal Space
Policy, and thanks to Duncan Lunan for the kind appreciation of the book he

Although Target Earth was published in the UK by Time Life Books, as Lunan
notes (and that would be the imprint he would have), my information is that
it is no longer for sale here. Elsewhere in the world it has been published by
Reader's Digest (certainly in North America and Australasia) and is still available.
Prospective purchasers might try or similar sources. Note that I will
receive no further payment no matter how many copies are sold (i.e. I am not
trying to boost my royalties).

I am informed that it has also recently appeared as a German translation. If
any readers know of other foreign language copies, please do let me know:
the fact is that publishers treat their authors like mushrooms*.

Kind regards,

Duncan Steel

*That is, they keep them in the dark and feed them compost (to employ a
polite euphemism).


>From Hermann Burchard <>

Dear Benny,

your helpful comments CCNet Feb 15 "NEO IMPACT WARNING TIMES: NOT AS
SIMPLE..."  caught my eye where you wrote "The chaotic nature of asteroid
orbits is such that we would be unable to calculate a 100 percent impact
probability for the impactor until perhaps 1 or 2 years before it actually
hits the Earth."  Unpredictability clearly is a hallmark of chaos, and the
question whether the existence of chaos had been proved for the Solar System
had been in the back of my mind, as I had kept reading on CCNet snippets
about resonance encounters of NEAs with Earth, and the "keyhole"

Stability of the Solar System, or its lack with chaos a related question,
has been an constant theme in mathematical research in the past century. The
general area of stability and chaos in dynamical systems has ramifactions in
areas far removed from Hamiltonian systems like the Solar System, such as
weather and turbulent fluid flow. Spectacular and difficult results have
kept mathematicians on the alert for new developments, which are occurring
all the time.  For the simplified weather model known as the Lorenz
equations existence of chaos has been shown only recently in an Uppsala PhD
thesis. For climate afficionados this has the implication that weather is
hard to predict.

There is a large literature, vastly exceeding my own limited insight. I
picked two reviews of articles, which might interest CCNet readers, out of
MATHEMATICAL REVIEWS, see below for copies.  One article is by Andrea
Milani, frequently featured on CCNet. Both articles happen to have the same
reviewer, himself author of numerous articles on stability of planetary

The mathematical concept of stability of solutions of differential equations
is not simple, there are many similar ideas, and chaos does not necessarily
imply instability in every sense of the word, provided you choose an
appropriate definition of stability, see the first article by Milani.
However, "remaining stable for millions of years" would not constitute
mathematical stability for most purposes.

The second review seems to suggest nonetheless that the long-standing
question of stability of the solar system, tied to some famous names of
mathematicians, has been, or should be expected to become, answered in the
negative.  One needs to remember that numerical simulations with Lyapunov
exponents greater than zero occurring do not constitute proof. These
exponents give a local spreading rate of orbits if positive, contraction if
negative. The suggestion of Mercury moving beyond Pluto, however, even in a
Lyapunov time of 3.5 billion years, seems a bit hard to swallow..? Doesn't
the Titius-Bode Law strongly suggest that the main planets have remained
stably in their orbits for the majority of the last 4.5 billion years?

Hermann Burchard

= = = = = =

Milani, Andrea (Pisa)
Proper elements and stable chaos.
>From Newton to chaos (Cortina d'Ampezzo, 1993), 47--78,
NATO Adv. Sci. Inst. Ser. B Phys., 336,
Plenum, New York, 1995.

Summary: "The long term evolution of the orbits of the asteroids is studied
by means of proper elements, which are quasi-integrals of the motion. After
a short review of the classical theories for secular perturbations, this
paper presents the state of the art for the computation of proper elements.
Recent theories are extended to a higher degree in the eccentricities and
inclinations, and to the second order in the perturbing masses;
they use new iterative algorithms to compute
secular perturbations with fixed initial conditions but variable
frequencies. This allows one to compute proper elements stable over time
spans of several million years, within a range of oscillations small enough
to allow the identification of asteroid families; the same iterative
algorithm can also be used to automatically detect secular resonances, that
is, to map the dynamical structure of the main asteroid belt. However, the
proper element theories approximate the true solution of the N-body problem
with a conditionally periodic solution of a truncated problem, while the
orbits of most asteroids are not conditionally periodic, but chaotic;
positive Lyapunov exponents have been detected for a large number of real
asteroids. The phenomenon of stable chaos occurs whenever the range of
oscillations of the proper elements, as computed by state of the art
theories, remains small for time spans of millions of years, while the
Lyapunov time (in which the orbits diverge by a factor (exp(1)) is much
shorter, e.g. a few thousand years. This can be explained only by a theory
which accounts correctly for the degeneracy of the unperturbed 2-body
problem used as a first approximation. The two stages of computation of mean
and proper elements are each subject to the phenomena of resonance and
chaos; stable chaos occurs when a weak resonance affects the computation of
mean elements, but the solution of the secular perturbation equations is

Reviewed by Florin N. Diacu

=  =  =  =  =  =

Marmi, Stefano (Florence)
Chaotic behaviour in the solar system (following J. Laskar).
S\'e9minaire Bourbaki, Vol. 1998/99.\par
Ast\'e9risque No. 266, (2000), Exp. No. 854, 3, 113--136.

In this nice paper, the author gives a comprehensive exposition of the
numerical results obtained by Jacques Laskar regarding the instability of
the solar system. Laskar had estimated that the Lyapunov time (which
measures the rate of exponential growth of the distance in phase space
between the orbits of two initially close points) of the inner planets is
about 5 million years. This means that in 3.5 billion years even Mercury
could be beyond today's orbit of Pluto.

Before getting into Laskar's methodology and results, the author surveys the
theoretical foundations of the field. He discusses Hamiltonian systems,
integrability, quasiperiodic orbits, KAM theory, Nekhoroshev's theorem,
Arnold diffusion, and frequency map analysis, to finally reach
the issue of Lyapunov exponents and chaos.

This is a readable paper with extensive references. We highly recommend it
to everybody interested in the stability of the solar system. However, the
reader should be cautious about historical statements, which are not always
objective. For example, the work of Haretu, who in 1878 was the first to
cast doubt on the stability of the solar system (against the claims of
Laplace, Lagrange, and Poisson), is barely mentioned.

Reviewed by Florin N. Diacu


>From Andrew Yee <>

[,,2-209576,00.html ]

[From Saturday, February 16, 2002 TIMES OF LONDON.]

Men are not wanted on sailing ship to the stars

Reports from the American Association for the Advancement of Science
conference in Boston

By Mark Henderson

WOMEN will set sail for the stars in as little as 50 years, aboard vast
spacecraft that look more like the Cutty Sark than the starship Enterprise,
NASA scientists have predicted.

Men need not apply: the all-female crew would probably take a sperm bank
rather than male astronauts to save on weight without losing the ability to

The spaceships that will carry the first interstellar travellers to Alpha
Centauri at a tenth of the speed of light will not be powered by the warp
drives or ion engines of Star Trek, but by light sails powered by lasers
measuring hundreds of miles across.

The first human beings to experience this new age of sail will embark within
50 to 100 years in spacecraft of at least a million tonnes that would
operate as self-contained miniature cities, according to Geoff Landis, of
NASA's Glenn Research Centre in Cleveland, Ohio.

Passengers should forget about booking a return ticket. It will take 43
years to get there and another 100 years to stop, with the original
astronauts' great grandchildren becoming the first to wake up to the dawn of
a different Sun.

Interstellar travel has often been assumed to be impossible because of the
difficulty of designing a lightweight engine with the power to propel a ship
4.3 light years to Alpha Centauri. Anything that might generate sufficient
energy would be too heavy.

Space scientists, however, are now increasingly confident not only that
humanity will travel to the stars, but also about the form that such
journeys are likely to take, Dr Landis, who researches space propulsion
systems, told the American Association for the Advancement of Science
conference in Boston yesterday.

"Often technology develops much faster than anybody expects," he said.

"It will probably happen in 50 to 100 years, though it probably won't be in
my lifetime."

An interstellar spacecraft, he said, could not carry an engine because of
the weight of its fuel. The best course would be to attach a life-support
module to a sail hundreds of miles wide but only a few millionths of a
millimetre thick.

"You would then shine an incredibly powerful laser beam on to the sail to
push it out to the stars as the wind pushes a sailing ship," Dr Landis said.
"The energy from such a beam could propel the ship to reach 10 per cent of
the speed of light, which is fast enough potentially for it to carry

The sails would be made of diamond, just a couple of molecules thick, for
maximum strength and resistance to heat, and the laser would take several
years to power up before producing its beam. The orbiting laser could fire
either an intense, single pulse or a continuous, focused beam -- either form
of energy could be caught by such a vast sail.

If the target speed were reached, the total journey would take 43 years.

That, however, is far from the end of the design problem. "You really want
to stop when you get there, and it's just possible you might want to come
back," Dr Landis said. "These are both as difficult as getting there in the
first place."

It would be possible to stop the ship using a magnetic parachute, a giant
magnetic field 60 miles in diameter that would create drag as it passed
through the tiny number of hydrogen atoms that exist in outer space.

"This might take 100 years, and the last part might need help from a
rocket," he said. It means a round trip of 200 to 300 years, assuming that
the return leg is possible.

The life-support module would have to carry everything the astronauts needed
for more than a century, including equipment for making oxygen, greenhouses
for growing food and a nuclear plant for generating power.

Dr Landis said: "After the long voyage without any men present, they may
discover that humanity doesn't actually need men after all and they'll
engineer a society without them. But then, maybe that will be better anyway.
It certainly might be worth a try."

Copyright 2002 Times Newspapers Ltd.

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