CCNet 04/2000 - 11 January 2000


     "No matter how remote, the danger from celestial objects is
     gradually prompting an international response, unlocking resources
     and setting the basis for a coordinated planetary defence against
     a faceless enemy... Governments are allocating more and more
     funds, equipment and personnel to monitor the skies”.
        -- Agence France-Presse, 10 January 2000

     "But the current odds are that a large NEO will strike with little
     or no warning because the world-wide search for NEOs is grossly
     under-funded and under-staffed".
        -- Michael Paine, 10 January 2000

    Andrew Yee <>

    Explorezone, 10 January 2000

    Benny J Peiser

    Andrew Yee <>

(5) 1999 LEONIDS
    Marc Gyssens <>

    Larry Klaes <>

    Bob Kobres <>


From Andrew Yee <>


Sunday, January 9, 2000, 11:07 AM EST

Asteroid menace moves out of the pages of sci-fi

PARIS (AFP) -- In the 1950s, the idea of the Earth being hit by an
asteroid, wiping out civilisation at a stroke, was the stuff of pulp
science fiction.

Today, space rocks are being taken seriously.

No matter how remote, the danger from celestial objects is gradually
prompting an international response, unlocking resources and setting
the basis for a coordinated planetary defence against a faceless enemy.

Dozens of observatories around the world now scour the skies nightly
for any threat from space. The United States has a dedicated deep-space
telescope on asteroid duty, and Japan is building one. The British
government last week set up a three-man task force to evaluate any
peril from the skies.

Each day, several thousand tonnes of cosmic debris fall to Earth, says
Jean-Eudes Arlot, director of the Institute of Celestial Mechanics at
the Paris Observatory.

Most of it consists of minute specks of dust released from passing
comets, or fragments of asteroids that smashed into each other millions
of years ago.

Objects of this size are harmless. Larger ones, about the size of a
pebble, provide an entertaining "shooting star," burning up from
friction with the Earth's atmosphere.

What worries space watchers are the bigger celestial wanderers --
brutes that measure several metres (yards) or more and race through the
heavens at up to 30 kilometers (20 miles) per second.

As was shown in 1994, when the tail of the comet Shoemaker-Levy 9
rammed dramatically into Jupiter, these release catastrophic energy on

An asteroid or comet measuring at least a kilometer (half a mile)
[sic] that slammed into Mexico's Yucatan peninsula around 65 million
years ago is believed to have caused the dinosaurs to die out.

It unleashed a firestorm and kicked up such huge volumes of dust that
vegetation could no longer get adequate light from the Sun. Plants
withered, and the impact resounded up the food chain.

Scientists agree that the risk of doomsday is very remote.

Yet every 100 years or so an object measuring 50 metres (165 feet)
smacks into the Earth, inflicting local devastation, according to
NASA's Jet Propulsion Laboratory (JPL).

A comet about 60 metres (200 feet) wide exploded over Siberia in 1908
with a force the equivalent of 600 times the Hiroshima bomb, reducing a
40-kilometer (25-mile wide) patch of forest to matchwood.

Cities the size of London or New York would be reduced to cinders by
such an impact. If the object hit the sea, it could trigger a giant
tidal wave, swamping low-lying areas.

The good news is that resources, ideas and organisation are quickly
improving mankind's knowledge of the threat.

Governments are allocating more and more funds, equipment and personnel
[sic] to monitor the skies. Data and watch duties are being shared
among astronomers and space agencies through a loose cooperative
effort, Spaceguard Foundation.

An international measurement of risk assessment, called the Torino
Scale, was agreed last year. The International Astronomical Union
(IAU), based in Paris, has been placed in charge of vetting any warning
to ensure the size of the danger and avoid any false alarm.

Big technical strides are also being made.

In less than two years, a deep space telescope operating at the White
Sands Missile Range in New Mexico has discovered more than 200 of the
700 or so known Near-Earth Objects (NEO), as these dangerous itinerants
are called.

A second large telescope is scheduled to start operating at the same

"It'll be another 10 or 15 years before we've detected most objects
more than a kilometer across," says Hans Rickman, the IAU's deputy

"Enormous progress has been made in plotting the trajectories of NEOs,"
says Arlot.

"Ten years ago, the margin of error would have been in the thousands of
kilometers, up to 10,000 kilometers (6,000 miles).

"Today, that margin is several dozen kilometers (miles), mainly thanks
to satellite technology that uses the stars as a measuring point when
the asteroid passes near by."

That sort of finessing is vital.

It helped to tone down a scare about the the most dangerous identified
NEO -- a kilometer- (half-mile) -sized asteroid, 1999 AN10, which is
due to skim past the Earth on August 7, 2027.

The latest arithmetic says 1999 AN10 could run as close as 37,000 kms
(19,000 miles) -- but no closer -- to the Earth.

"The probability of a collision in 2027 is essentially zero," JPL's NEO
Program says.

But, it adds, there is "about one chance in 10 million" that the
asteroid will hit the Earth when it returns on its orbit around the Sun
in 2039.

Such observations could give the Earth years of warning about impending

Yet what could be done if the alarm sounded?

Experts caution against Hollywood heroics of blasting the asteroid into
smithereens with nuclear bombs, as this could merely cause it to split
into chunks that could rain down over a larger area.

"It could be possible to land a probe on to it and use solar power to
nudge it out of its orbit," said Arlot.

"But the interception would have to be done over a great distance and
the operation would have to be unfold over several months or years. In
theory, it's possible, but at the moment, despite the progress, that
remains in the realm of science fiction."

Copyright 2000 Agence France-Presse. All rights reserved.


From Explorezone, 10 January 2000

Simulating armageddon ON YOUR PC: Asteroid Impacts with Earth

By Michael Paine for

Millions of uncatalogued space rocks careen through interplanetary
space, and Earth is one of the many sitting ducks in the cosmic
shooting gallery. Although centuries can pass on Earth without a
catastrophic strike, waiting impassively to be hit is seen by many
experts as a clear and possibly deadly gamble.. But what are the
odds? And what would happen under different types of impacts?

As with almost anything that can be simulated, the odds and 
consequences of an asteroid strike have been programmed into a computer
software package.

I ran some scenarios on the new software, created by planetary 
scientist John Lewis from the University of Arizona. The results,
described below, are not official predictions, but they do lay out some
frightening possibilities that put the threat of rocks from space into
tangible terms, while at the same time pointing to the need to search
for the uncharted asteroids and comets (known as Near Earth Objects or
NEOs) that threaten our civilisation.

Lewis' software uses a Monte Carlo analysis to calculate the human
fatalities resulting from impacts. This works by generating random
numbers for the size and type of NEO and the human population density
at the impact site. The process is based on the actual distribution of
these factors. It includes fatalities from "airbursts," where the NEO
explodes in a devastating fireball several miles from the ground.

The consequences are similar to those from a nuclear bomb and estimates
of fatalities are based mainly on research with nuclear weapons.
Another danger modelled by the program is the risk of tsunami swamping
coastal cities hundreds or thousands of miles from the site of an ocean

A million years of bombardment

In one run I simulated a total of one million years, looking at the
worst event in each of 10,000 centuries.

I want to stress that these are not predictions and that no known NEOs
are on a collision course with Earth.

Although one million years seems a very long time, bear in mind that
impacts do not run like clockwork -- they could occur at any time. An
event which happens once in one million years of the simulation has a
one-in-a-million chance of happening in the next twelve months. This
should not be dismissed as unimportant, particularly if it could
involve billions of deaths and the end of civilisation. After all, many
optimistic people around the world regularly buy lottery tickets where
the chance of winning first prize is one in 30 million or worse.

The chance of getting dealt a royal flush in 5 card poker is about one
in half a million.

In my simulation the total death toll during one million years was 7.5
billion. This represents an average of 7,500 fatalities per year and is
higher than the 3,000 fatalities per year generally quoted by
scientists. However, nearly half of these fatalities occurred in one
devastating event that wiped out half of the world's population -- a
possible outcome in the real-life gamble with rocks from space.

To put the NEO death toll in perspective, it lies somewhere between
that of airline crashes (700 per year) and earthquakes (10,000 per

Looking at the results

Fatalities topped 1 million in 2% of the centuries. Nearly two-thirds
of centuries had no fatalities.

In a further 5 percent of centuries the worst event happened in a
remote location and caused less than one thousand fatalities. Such
events would probably not been blamed on NEOs, for lack of being
spotted. Another of 5 percent centuries had only had tsunami
fatalities, with an average of 100,000 fatalities per tsunami event.
Many of these tsunami events would not have been linked to a NEO
since the ocean impact happened well away from eyewitnesses.

Overall, some 70 percent of centuries may have had no reported
fatalities from NEOs. This may help to explain the general lack of
awareness of the NEO threat by the public and politicians.

Surprisingly, 1,207 fatal impacts involved NEOs with a diameter less
than 50 yards. Most did their damage in an airburst of around 10
megatons -- like that of a "small" H-bomb.

There were several sobering impact events in the simulation. They are
described below. Geographic names are arbitrary and are intended to
give an indication of the population density and landforms of the
impact site (as well as dramatic effect).

Big blasts

First the really big ones -- asteroids or comets a mile or more across.
These are civilisation-destroying events that leave little opportunity
for disaster recovery. Estimates of the NEO population suggest that,
over a period of one million years, about 5 such impacts can be
expected. By chance, this is the number produced in the simulation.

During the 133rd Millennium a 1.3-mile-wide comet hits the American
Midwest at a speed of 100,000 mph. The blast, equivalent to 3 million
megatons of TNT or 60,000 H-bombs, kills 7 million instantly and makes
a crater 20 miles across. Within days the skies around the globe darken
from the dust injected into the atmosphere. Sunlight is blocked. Crops
fail and, over the next year, half of the Earth's human population
dies, mainly from starvation.

In the 621st Millennium a mile-wide comet slams into Mongolia. "Only"
300,000 people die instantly, but the dust from a crater 13 miles
across darkens the skies around the globe. Some 900 million die from

In the 952nd Millennium a 1.2-mile-wide comet hits central Africa.
About 3 million people are killed instantly. An 11-mile-wide crater is
formed. Later, 500 million starve to death around the globe.

During the 11th Millennium a 1.2-mile asteroid hits the southern
Atlantic Ocean 400 miles off the coast of southern Argentina. A tsunami
250 yards high sweeps 50 miles inland and kills 300,000. The climatic
effects are less severe than with a land impact, but 400 million still
die from starvation due to these effects.

An almost identical event, this time off the northern coast of Russia,
occurs in the 699th Millennium.

Quirky blasts

There were several events that were unusually deadly -- a matter of
bad luck for 54 million people:

136th Millennium: A 200-yard-wide asteroid hits the South China Sea
just 300 miles from Hong Kong. A 40-yard-high tsunami sweeps the coast
and kills 18 million people.

20th Millennium: An asteroid just 70 yards across explodes in the skies
14 miles above London. 10 million are killed in the 80-megaton blast
and firestorm.

273rd Millennium: A 50-yard-wide comet travelling at an unusually fast
150,000 mph explodes in the atmosphere 25 miles above Mexico City. 14
million are killed by the 110-megaton blast and firestorm.

721st Millennium: An almost identical event occurs over Manila, killing
12 million.

The lessons from the simulation

Comets accounted three-quarters of the fatalities, due mainly to the
Midwest event in the United States. That event was caused by a
long-period comet that spent tens of thousands of years out beyond
the orbit of Neptune before diving into the inner solar system.

The simulations show that unusual events can be killers. In his book,
Lewis points out that the simulations generally produce a greater
number of casualties from small NEOs than would be expected from
calculations involving "typical" values. Unfortunately, it would be
extremely difficult for current technology to reliably detect such
small, but deadly, objects.

The situation is very different for the civilisation-destroying giants
because most can be easily spotted from Earth using existing
technology. Given decades of warning, we can develop the space
technology to nudge them into a non-threatening orbit. But the current
odds are that a large NEO will strike with little or no warning because
the world-wide search for NEOs is grossly under-funded and
under-staffed (as one frustrated scientist put it -- less than the
number of staff at a typical McDonalds restaurant).

Lewis sums up the situation succinctly: "Of all the natural hazards
facing Earth, impacts are the most dangerous. Unlike native hazards of
the Earth's surface, impacts know no size limit. Their effects can be
devastating over the entire surface of the planet. They are the only
credible natural threat to human civilisation. But impacts, especially
those of large bodies, are both predictable and avoidable.

"The Near Earth Object (NEO) population constitutes both an
unprecedented hazard and an unparalleled opportunity," Lewis says.
"It is sometimes said that there is a fine line that separates a threat
from an opportunity. The near-Earth asteroids present us with just this
dilemma. They present us with an intelligence test of the highest order,
with the highest possible stakes for the human race."

Copyright 2000, Explorezone




17-22 February 2000 - Washington DC

Symposium: Unpredictable Natural Events of Extra-Terrestrial Origin:
Their Impacts on Humanity (Organised by Rolf M. Sinclair)

How many Cosmic Impacts have punctuated Earth during the last 10,000
Years? BENNY J PEISER, Liverpool John Moores University, School of
Human Sciences, Liverpool L3 3AF, UK,

Cosmic impacts have punctuated life on Earth repeatedly. Such
extraterrestrial perturbations, depending on the size, physical nature
and hence the cohesive strength of the impactor/s, can have
catastrophic effects on the ecological system in a variety of ways: i)
low or high level multimegaton explosions of fireballs which destroy
natural and cultural features on the surface of the Earth by means of
floods, blasts and seismic damage, ii) massive high level influx of
cosmic dust high above the stratosphere which causes a dramatic drop of
global temperature and which can lead to the suspension of agriculture,
iii) massive high level influx of cosmic chemicals (associated with
dust) with, as yet, incalculable biochemical potentials which may be
harmful to DNA. Whilst a dozen Holocene impact craters have been
confirmed to date, the majority of impacts that occurred during the
last 10,000 years have not been detected yet. This is due to a limited
focus on crater producing events. Tunguska-like impacts or
"Super-Tunguskas" are thereby taken out of the equation. Due to their
catastrophic detonation above ground (or in the oceans), they often
leave no obvious fingerprints behind. Tunguska-like impacts occur every
100 years or so. Occasionally, massive high level multimegaton
explosions and widespread atmospheric and/or oceanic impacts triggering
ecological crises on a hemispheric, continental or even global scale.
Current risk assessment is based on the statistical analysis of the
number of known impact structures in addition to the current asteroidal
flux. However, there are other sources of cosmic input capable of
triggering ecological crises without producing impact craters: cosmic
dust veils, atmospheric impacts and oceanic impacts. I will present
different sources of proxy data for paleocatastrophic reconstruction
which are relevant for the search of yet undiscovered Holocene impacts.

For more information see:

MODERATOR'S NOTE: I will be visiting North America in mid
February and would be available for lectures at request.


From Andrew Yee <>


7 January 2000, 5 pm PST

Strange Ice Flavors on Pluto's Moon
By Robert Irion

Astronomers have taken their first detailed look at Pluto's companion
Charon, the most distant known moon in the solar system. This dark body
appears to be covered with a mixture of water ice and ammonia ice, a
chilly brew quite different from the frosts of methane, carbon
monoxide, and nitrogen ices that sheath the surface of Pluto. The
marked contrast is surprising, for many astronomers have regarded Pluto
and Charon as a "double planet."

Pluto and Charon orbit each other every 6.4 days at a distance of just
20,000 kilometers -- about 20 times less than the separation between
Earth and its moon. This tight pirouette makes Charon exceedingly
difficult to study and obscured its very presence until 1978. Images of
the two objects usually blur together even in powerful telescopes. A
rare night of spectacular atmospheric conditions at the W. M. Keck
Observatory in Hawaii last May allowed planetary scientist Michael
Brown of the California Institute of Technology in Pasadena to
distinguish the light from Pluto and Charon more clearly than ever

Brown teamed with Wendy Calvin, a spectroscopy expert at the University
of Nevada, Reno, to analyze the outer skin of Charon based on the
spectrum of infrared light reflected from the moon. They saw a surface
dominated by crystalline water ice, commonly seen on other moons in the
outer solar system. But a curious dip in part of the spectrum demanded
further explanation, the team reports in today's Science. Using models
of the light reflected from a variety of ices and minerals, Brown and
Calvin deduced that the most likely cause is ammonia ice, which until
now astronomers had seen only in comets.

Early in the solar system's history, a large object probably struck
Pluto; the debris later coalesced into Charon, astronomers believe.
Volcanoes driven by the heat of the impact may have coated the moon's
surface with a slushy ammonia-water mixture. Then, after the heat faded
away, Charon would have frozen solid. Pluto, nearly five times more
massive than Charon, retains a shroud of methane, carbon monoxide, and
nitrogen in a thin atmosphere and as surface frosts, Brown says. In
contrast, Charon's gravitational pull is too feeble to hold on to those
volatile gases.

Planetary scientist Eliot Young of the Southwestern Research Institute
in Boulder, Colorado, isn't yet sold on Charon's ammonia ice. "It's
worth following up, but it's hard to check an exhaustive list of
compounds when you are trying to match a small depression in a
spectrum," he says. Even so, Young is excited by the prospect of
learning more about Charon's composition. "If you're interested in what
the early solar system was made of, Pluto, Charon, and comets
are among your best bets."

1999 The American Association for the Advancement of Science

[Extracted from INSCiGHT, Academic Press.]

(5) 1999 LEONIDS

From Marc Gyssens <>

A preliminary analysis of visual data on over 1/4 million meteors seen
during the 1999 Leonid display, to appear shortly in the December 1999
issue of WGN, the Bimonthly Journal of the International Meteor
Organization, is already available on the Organization's Web site
(, and we invite you to consult it!

Marc Gyssens
WGN, Editor-in-chief


From Larry Klaes <>

Although they know that bacteria can survive a tremendous amount of
time in the cold of space, astrobiologists aren't sure how they can
handle atmospheric re-entry on a meteorite. To test their theories,
they've strapped artificial meteorites filled with bacteria onto a
Russian space probe which will be launched into space and then
returned to Earth.


From Bob Kobres <>

Desert Wetness Changes Challenge Current Climate Ideas

Where does one go to find information about tropical rainfall patterns
since the last major glaciation? Try the driest desert of South
America. That's the approach taken by University of Arizona
geoscientists Julio Betancourt and Jay Quade.

With assistance from several UA students, they are combing the Atacama
Desert in northern Chile for clues on regional climate changes over the
past 40,000 years. Their findings may force the scientific community to
rethink the accepted views on the timing of wet and dry periods in the
region -- and the importance of the tropics during times of climate


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    Alain Maury <>

    Duncan Steel <>

    Victor Noto <>

    Jon Richfield <>

From Alain Maury <>

Dear Benny,

I doubt that Jim Gibson, who named an asteroid after his beloved cat,
is a reader of the CCNet, so let me tell the underlying story behind
the naming of asteroid Mr Spock as Jim Gibson told it to me:

One of the possible conditions for naming a minor planet for a person
is that he/she (it?) must have contributed in solar system research. Mr
Spock (the cat) was very often spending nights with Jim and his wife
observing, and by doing this, Jim felt it had contributed to solar
system research much more than many observatory directors... ;-)

In more recent times, Jean Mueller who is the senior observer at the
Palomar/Oshin Schmidt, had wanted to name one of her asteroids after
her beloved "Pepper Cat" who had just passed away. This, however, was
refused by the naming committee, and a compromise was found by naming
it 4257 Ubasti, the Egyptian god with a cat's face. Nevertheless,
Schmadel's "Minor Planet Name Dictionary" has a mention of Pepper Cat in
the citation for asteroid Ubasti.



From Duncan Steel <>

Dear Benny,

In CCNet of 2000/1/6 you carried a discussion from Michael Paine in
which he quite correctly emphasized that the people of Australia - the
vast majority of whom live on coastal plains facing onto vast oceans -
face an unappreciated but large risk from tsunamis. He wrote:

"Four potential sources of tsunami are described: earthquakes, 
undersea volcanoes, submarine landslides and asteroid/comet impacts."

Whilst I was resident in Australia, I once took out my household
insurance policy to look at the small print. Therein I found that
tsunamis were *defined* as being large waves caused by any of the
*first three* causes which Michael mentioned. That is, "asteroid/
comet impacts" were *not* included in the insurers definition of

From this it would appear that not only are Australians at risk from
impact-generated large waves, but also their insurers would not cover
them against losses sustained through such a source. Provided the
insured parties (and indeed the insurance companies) actually survive,
of course.

My note is whimsical, if one can joke about such things, but it has a
point at the end. Say we all started writing to our insurers asking
whether we *are* actually covered against losses caused by asteroid/
comet impact, through tsunamis or otherwise. At first the insurance
companies would just say "Yes, of course." After a dozen letters they'd
decide they should look into it. Then when they discovered the facts
for themselves, they'd get upset, and the proverbial would really hit
the fan. Because the annual expectation of loss due to such
catastrophes for houses in Sydney, say, is of the same order as the
house insurance premiums currently charged. The insurance companies
would thus have two choices: (a) Greatly increase the premiums; or
(b) Write into their smallprint terms which specifically exclude
impact-related damage.

Now, wouldn't that get things moving?


Duncan Steel


From Victor Noto <>

Hi Jon,

Nice article in CCNET on Jan 7, 2000 entitled A FEW CITY-BUSTERS BETTER
THAN ONE DINO-KILLER? which sums up my feelings on the subject pretty
well. Although a five year warning is considered too short a time by
many experts, I think every effort will be made to do something about
diverting such an dino killing object from space.

Actually five years is a optimistic scenario and a more realistic time
interval according to Dr. Duncan Steel, Dr. David Morrison and others
is a few seconds. But even a comet would probably only give a few years
warning at best since they come out of the Oort cloud rather suddenly.
So you see as bad as you made our threat from near earth objects, the
human condition is actually worse.

Ultimately the only solution to the problem of NEO's civilization
destroying impacts is to be out there as a permanent inhabitant of
inter solar space to either divert such objects when and if detected or
to survive if earth is greatly impacted.

We need time and no one knows for sure if we have time and the will to
do it. Perhaps we will need to genetically engineer a new race of
humans to survive the rigors of space.  All will eventually be possible
if the will and time is there to do it.  I personally think there is
not the will or time and man will go the way of the dinosaur.


My take on threat:

Victor D. Noto - Kissimmee, FL 34747
Lat 28.283 Long, -81.417
Website theme quote: "Life really is a Rock and the Big Rock giveth and
taketh away all life!!"


Dear Victor

May I briefly respond to your comment. While Jon has raised a
hypothetical question which may have to be addressed at some unknown
time in the future, I regret to say that I find your response somewhat
In some rare cases, a five year warning period to prevent a potential
impact might indeed be too short given our *present* technology. But in
50 or 100 years time, a 5 year warning period may be more than enough.
Who knows what advances will be made during the 21st century - and the
odds of a 10km dino-killer (or even a 500-1000m object) hitting earth
during the next 100 years are extremely small.
In view of the fact that - during the last 20 years or so - we have
begun to realise this cosmic threat, and are beginning to develop a
defensive capability, the human condition is actually much better than
at any stage of our long evolutionary history (during which we were
unable to do anything but to pray).

Yet neither prayers, nor space migration or genetical engineering are
effective messures to protect the world's population against the
potential impact threat. Instead, there are realistic and
technologically viable methods which should - given some time - be enough
to safeguard life and civilisation on our planet.
The fatalistic assumption that "there is not the will or time and man
will go the way of the dinosaur" is, I regret to say, mainly based
on rather pessimistic feelings. And these, I am sure you will agree,
should not blur our future potential for self-protection.

With best wishes,



From Jon Richfield <>

Hello Benny,

My note has elicited comments from Victor Noto among other
correspondents, and indirectly from you. To all of you thanks. A few
further comments from me:

First an extract from my reply to anonymous correspondents whose time 
is too much at a premium at present, to participate fully:

(Jon)>I notice in retrospect that I made a booboo of an order of
magnitude in the diameter of the dino-killer size.  No matter, it does
not affect the principle. <

(Correspondent) You have questioned the view that it is better to leave
the object intact than to smash it into an unmanageable swarm of
particles. I too distrust that view because in the first place letting
events take their course will certainly lead to total disaster. 
Smashing the object would leave large and small fragments and the small
ones will be relatively harmless, while the chances are fair that some
of the large masses might miss the planet altogether. 

(Jon) Just so. My main reservation is that for certain size ranges this
would mean that say a country-buster would be replaced by a gaggle of
city-busters.  Now, if the city-busters all land in the country which
would have been wiped out anyway, that would be an obvious profit to
many and a loss to none.  However, that would be a most unlikely
scenario. Very likely someone would get the chop who otherwise would
have got off scot free and such victims would have a legitimate gripe,
even if the human population as a whole profited. In fact, it might
even be that two neighbouring countries were at each other's throats and
as a result of the tinkering one that had been the predicted impact zone
would no longer be destroyed, while the other would now be, not actually
destroyed, but severely and murderously peppered, even ruined. Serbia
and Albania would be examples, or India and China or Pakistan. Even
within one country there could be difficulties; Would Quebec be willing
to sacrifice Montreal just to save Alberta? There are precedents for
this kind of thing; in WWII there were difficulties about fooling the
Germans to deflect the V1s from London to the rural southern counties.<

(Correspondent) This does however leave us with a situation which is
altogether uncontrollable and that is the basis of the concerns of the
anti-smashing brigade...

(Jon) Well, not absolutely uncontrollable; the assumption is that the
upper limit of the consequences of the intervention be lower than the
lower limit of the unmitigated impact, given reasonable levels of
confidence. Mind you, given the assumptions of a marginal time scale
and of far greater than marginally self-interested, probably
self-aggrandising committees making the decisions, I would have
precious little faith in the wisdom and good faith of their decisions,
but then I am a cynic, so surely I am putting the whole matter in too
bleak a light.  

One correspondent also expressed understandable reservations on the
hazards associated with the necessary testing and deployment of nukes
on the necessary scale. Though I share his concerns in principle, I
was more optimistic and replied in part as follows:

...The threats from the large impactors dwarf even direct nuclear
threats, let alone tests, pretty decisively. Secondly we have a lot of
bombs that don't really need testing, though I understand that there is
some wailing about the need to test them from time to time to prove
that they are still in good enough nick to take out any notional enemy
on demand.  Thirdly, if it were decided on good grounds that such bombs
as we still had were OK for frying nasties, but not well designed for
surgical engineering or steering of asteroids and comets, then they
could be tested underground under international scrutiny without much
pollution, certainly with negligible effects compared to those of the
threats they were intended to avert.  Again, given that we had a
reasonable idea of the effects of the bombs, we could (should, in fact)
send up a few to divert the orbits of a disposible rock or two to
confirm that our engineering is competent and effeective. These things
always sound so simple, but in practice something always happens that
had no business on the agenda.  There should be no difficulty in
finding a disposible target in an orbit safe for the study.

Victor responded kindly, though rather pessimistically and you replied.
My reactions are as follows:

> In some rare cases, a five year warning period to prevent a potential
> impact might indeed be too short given our *present* technology. But
> in 50 or 100 years time, a 5 year warning period may be more than
> enough.

I am hesitant to rely on new magic from the treasure chest of future
technology, which often exceeds our expectations, but hardly ever in the
form we expect. However, even given simple extensions of our current
technology, I can imagine a pretty good improvement in our reaction
times at a modest cost. Suppose for instance that we park in lunar
Trojan orbit, a number of craft bearing whatever deflection engines our
engineers decide have the best prospects of success, whether bombs or
nuclear powered thrusters or anything else desirable. They could be
deployed at very short notice and with their greatest problem already
overcome: getting close to Earth's escape velocity. There may also be a
case for deploying other parcels at other strategic points throughout
the Solar system so that we could intercept any serious threat within a
year or two.

It is not as though this would be a major extravagance; deploying and
maintaining such stations would be of incalculable scientific value,
both "pure" and "applied". They could logically be observation stations
for all kinds of effects, solar, astronomical, NEO tracking,
cosmological; you name it.

> In view of the fact that - during the last 20 years or so - we have
> begun to realise this cosmic threat, and are beginning to develop a
> defensive capability, the human condition is actually much better
> than at any stage of our long evolutionary history (during which we
> were unable to do anything but to pray).

Any practical reaction is better than none and our soundest basis for
hope is that the more probable the impact, the smaller it is, and near
misses are more frequent than actual impacts, so we are likely to have a
few practice runs before the Big One comes along.

Also, I don't understand Victor's sources' remarks on our having only
seconds of warning. That could happen with dog killers, but even a
modest space watch should give us a good probabiity of timely warning of
city busters.

> Yet neither prayers, nor space migration or genetical engineering are
> effective messures to protect the world's population against the
> potential impact threat. Instead, there are realistic and
> technologically viable methods which will - given some time - be
> enough to safeguard life and civilisation on our planet.

As I see it, this needs a bit of qualification. I constructed a scale
of classes of impact scales some time ago and if you no longer have it
to hand, I can exhume it. We can in principle handle anything up to
dino-killers, given sufficient warning, but by the time we are looking
at planet busters we have no foreseeable prospect of deflecting them, no
matter how much warning we get. For those we would like a few centuries
of warning, not to safeguard life on the planet, but to establish a
colony(ies) in space or on other planet(s). Yes, we could at best
rescue a viable genetic and technological nucleus, but consider the

>...pessimistic feelings... should not blur our future potential for
> self-protection.

This is the crux of the matter. If we curl up and die, we really must
die. If we take a sufficiently positive view of the matter, the spur of
the perpetual NEO threat could be just what humanity needs, to break out
of our sterile and eventually doomed existence on this planet. To be
sure, a few billion years or so is a long way to look ahead to certain
destruction, but there is no reason to pre-empt it by falling prey to
disastrous little rocks or climate shifts or eruptions every few
thousand years or so.

On a global scale the expenditure would be trivial and the incidental
benefits considerable.

Them's my sentiments anyway.



CCCMENU CCC for 2000