PLEASE NOTE:


*

CCNet 83/2002 - 15 July  2002
-----------------------------


"A small asteroid exploding in the Earth's atmosphere could
accidentally cause a nuclear war if "trigger-happy" nations mistook it
for a first strike attack, experts have warned. Each year about 30
asteroids measuring a few yards across pierce the atmosphere and
explode. Even the small ones can release as much energy as the atom bomb
dropped on Hiroshima. Between eight and 10 countries now have nuclear
weapons, and not all have effective early warning systems able to
distinguish the explosions from a missile blast. This has led to
scientists and military chiefs calling for a new warning centre that would
make asteroid detections available to governments around the world."
--Press Association, 14 July 2002


(1) ASTEROIDS 'COULD SPARK A NUCLEAR WAR'
    Press Association, 14 July 2002

(2) NEO SEARCH EFFORTS NEED MORE SUPPORT
    SPACEFLIGHT NOW, 12 July 2002

(3) SEARCH FOR VULCANOIDS COULD UPSET CURRENT THEORIES
    The Toronto Star, 14 July 2002

(4) EARTHQUAKE FORECASTING: SATELLITE SYSTEM MAY PROVIDE WARNING
    Space.com, 12 July 2002

(5) "CONTAMINATION RULED OUT": INDIAN SCIENTISTS CLAIM TO HAVE FOUND AMINO
ACIDS IN METEORITE
    Indo-Asian News Service, 13 July 2002

(6) THAT NIGHT IN TEL AVIV
    Richard Clark <rclark@lpl.arizona.edu>

(7) I DON'T THINK WE NEED TO NUKE ASTEROIDS
    Konrad Ebisch <kebisch@lgc.com>

(8) OF DRAGONS AND OTHER MATTERS: REPLIES TO MELFYN THOMAS'S COMMENTS, CCNET
63/2002 - 24 MAY
    Alastair McBeath <vice_president@imo.net>


=================
(1) ASTEROIDS 'COULD SPARK A NUCLEAR WAR'

>From Press Association, 14 July 2002
http://www.theherald.co.uk/news/archive/15-7-19102-0-29-1.html

A SMALL asteroid exploding in the Earth's atmosphere could accidentally
cause a nuclear war if "trigger-happy" nations mistook it for a first strike
attack, experts have warned.

Each year about 30 asteroids measuring a few yards across pierce the
atmosphere and explode. Even the small ones can release as much energy as
the atom bomb dropped on Hiroshima.

Between eight and 10 countries now have nuclear weapons, and not all have
effective early warning systems able to distinguish the explosions from a
missile blast.

This has led to scientists and military chiefs calling for a new warning
centre that would make asteroid detections available to governments around
the world.

In June, an asteroid estimated at five to 10 yards across exploded high
above the Mediterranean Sea with the force of a one-kiloton bomb.

Experts in Washington last week discussed what might have happened had the
burst occurred over India or Pakistan. The two nuclear powers were teetering
on the brink of war at the time.

Air Force Brigadier-General Simon Worden, deputy director of operations at
US Space Command, raised the frightening scenario at a US Senate round-table
meeting on asteroids.

He was reported to have told the meeting: "Neither of those nations has the
sophisticated sensors we do that can determine the difference between a
natural NEO (near-earth object) impact and a nuclear detonation.

"The resulting panic in the nuclear-armed and hair-trigger militaries there
could have been the spark for a nuclear war."

Asteroid expert Dr Benny Peiser, from Liverpool John Moores University, said
there were an estimated 100 million small asteroids flying around the solar
system. A large percentage of them crossed the Earth's orbit. Dr Peiser
said: "This is a really serious issue. When you have such an
explosion in the wrong place at the wrong time, say over Pakistan, India, or
Israel, it can easily be misinterpreted as a first strike.

"These objects penetrate the atmosphere for a few miles and detonate. All
you detect is a large explosion. Your sensors only pick up the energy
release, you can't tell that it was so many miles up in the atmosphere.

"If you're waiting for another country to strike first and some
trigger-happy person is looking for an excuse you can imagine what might
happen."

At present the space agency Nasa only tracks objects larger than one
kilometre in diameter.

The US has a set of hi-tech military satellites keeping a round-the-clock
vigil for missile launches and nuclear detonations. They also spot the
flashes of asteroid explosions. General Worden and others want to see a new
warning centre set up that would make the detections available to
governments around the world as soon as they happen.

Dr Peiser said: "If, for instance, we had a major meteor blast over a
critical area like India or Pakistan, that information would be sent
immediately to the governments in question. The US already makes the
information available on an informal basis, but it takes about two months or
so."

A study looking at the issues involved in setting up a warning centre was
now moving through the US Defence Department.

Another potentially dangerous incident occurred on July 4, American
Independence Day. Israeli officials reported a missile exploding a few miles
from an El Al jet flying over the Ukraine.

The situation was sensitive because in October last year a Ukrainian missile
fired by accident shot down a Russian plane, killing all 78 people on board,
most of them Israeli.

In the case of the El Al jet, the Ukrainian authorities insisted that no
missiles had been fired near the plane and suggested the flash might have
been a meteor explosion. This now seems the most likely explanation.

Copyright 2002, The Herald

ASTEROIDS 'COULD TRIGGER NUCLEAR WAR'
http://news.bbc.co.uk/hi/english/sci/tech/newsid_2128000/2128488.stm
ASTEROID EXPLOSIONS MAY BE CONFUSED WITH NUCLEAR ATTACK: SCIENTISTS
http://www.abc.net.au/news/scitech/2002/07/item20020714213340_1.htm

==============
(2) NEO SEARCH EFFORTS NEED MORE SUPPORT

SPACEFLIGHT NOW, 12 July 2002
http://spaceflightnow.com/news/n0207/12neo/

BY JEFF FOUST

Congress should provide more funding to efforts to search for near-Earth
objects (NEOs) as well as studies of the best techniques to deflect any
potentially hazardous NEOs, a panel of experts said this week.

"The Asteroid Threat" roundtable meeting, held Wednesday in a U.S. Senate
office building, was organized by the space lobbying group ProSpace to bring
together policymakers and experts to discuss the threat that NEOs pose to
the Earth and the best ways to deal with that threat.

NASA currently funds several efforts to search for NEOs, noted Colleen
Hartmann, director of NASA's solar system exploration system. Foremost among
those programs is the Lincoln Near Earth Asteroid Research (LINEAR) program.
LINEAR, operated by MIT's Lincoln Laboratories, uses two 0.9-meter
telescopes in New Mexico with sensitive CCD cameras to scan the skies;
LINEAR has discovered about 1,000 NEOs since 1998. LINEAR and the other
programs cost NASA about $4 million a year, Hartmann said.

Those efforts are doing a good job of finding relatively large NEOs. A total
of 603 NEOs one kilometer in diameter or larger have been found to date, and
astronomers estimate that there are approximately 1,000 NEOs of that size
overall. At current discovery rates Hartmann said that NASA should achieve
its goal of discovering 90% of NEOs that size by 2008.

However, of growing concern are smaller NEOs. One example is 2002 MN, which
was discovered by LINEAR on June 17. The asteroid, estimated to be between
50 and 120 meters across, passed within 120,000 kilometers of the Earth on
June 14 - three days before its discovery. Had it struck the Earth it would
have had enough destructive power to wipe out a large city.

While small NEOs like 2002 MN are discovered on a regular basis by search
programs like LINEAR, they are not the focus of these efforts. "NASA and
these programs are not concentrating on these small objects," said Brian
Marsden, director of the Minor Planet Center at the Harvard-Smithsonian
Center for Astrophysics. "It would be impossible with current facilities."

Even if search efforts concentrated on these smaller bodies, it could
overwhelm those who catalog NEOs. Marsden estimates that there are about one
million NEOs 50 meters across or larger; only 2000 NEOs of any size have
been discovered. However, the Minor Planet Center has only 2.5 full-time
employees, Marsden noted, who work 16-hour days seven days a week just to
keep up with the current rate of asteroid and comet discoveries.

Hartmann said that NASA is currently concentrating on large NEOs because
objects one kilometers or larger have the potential to cause global
devastation. However, she acknowledged that smaller objects "can still make
for a bad day" if they collide with the Earth, and said that NASA is
initiating a feasibility study for conducting searches for smaller objects.

Disseminating data of NEO discoveries and related phenomena may turn out to
be more important than searching for NEOs themselves. U.S. Air Force
Brigadier General Simon "Pete" Worden of U.S. Space Command, speaking as an
expert and not representing the Air Force, said that a bright flash was
observed by U.S. early warning satellites over the Mediterranean Sea on June
6. The flash, the equivalent of a 20-kiloton nuclear explosion, was quickly
determined to be a meteor. However, Worden noted, had the explosion took
pace a few hours earlier at the same latitude, it would have occurred over
India or Pakistan at a time when tensions between the nation were extremely
high. Without access to the U.S. satellite data, the flash could have been
mistaken for a nuclear attack, Worden believes. "It's quite possible it
could have triggered a nuclear war," he said.

To prevent something like this from happening in the future, Worden
advocates creating a coordinating body that could collect and disseminate
data like satellite observations to both track NEOs and alert governments
when events like those on June 6 take place. He said it could be handed by
the U.S. Space Command using existing facilities and no more than five to
ten personnel.

Proposals like Worden's, as well as efforts to expand current NEO searches,
would require additional funding or approval by Congress, and the purpose of
the roundtable session was to educate Congressional staffers on the issue.
Increased support for NEO efforts already has the support of some members of
Congress. Small NEOs are "a grave threat we should be investing in," said
Rep. Dana Rohrabacher (R-CA), chairman of the House Science Committee's
space subcommittee. "The potential danger of global warming is nothing
compared to the potential danger of near-Earth objects."

Studying NEOs also has a benefit, Rohrabacher noted. The same NEOs that pose
a threat to the Earth could also be rich in minerals and ice that would be
beneficial to future exploration and development of space. By exploiting the
resources of NEOs, he said, "we can turn these lemons into lemonade." 

2002 Pole Star Publications Ltd

==========
(3) SEARCH FOR VULCANOIDS COULD UPSET CURRENT THEORIES

>From The Toronto Star, 14 July 2002
http://www.thestar.com/NASApp/cs/ContentServer?GXHC_gx_session_id_=5dd63d457
b622c34&pagename=thestar/Layout/Article_Type1&c=Article&cid=1026143400728&ca
ll_page=TS_Canada&call_pageid=968332188774&call_pagepath=News/Canada
 
A century ago, most astronomy books included a chapter on the planet Vulcan.
No, they weren't talking about Mr. Spock's home planet. This planet Vulcan,
named after the ancient Roman god of fire and metal working, was supposed to
exist in our own solar system, between the planet Mercury and the sun but
too close to the sun to observe.

The predicted planet Vulcan has never been seen and in fact it doesn't
exist. But back then astronomers had good reason to assume it was there.
Researchers had noticed an unexplained peculiarity in the orbital motion of
Mercury. The gravitational influence of Vulcan was the only reasonable
explanation for it.

It took the genius of Einstein's relativity theory to explain that the
motion of Mercury was caused by the warping of space and not by the supposed
Vulcan. It was this proof of Vulcan's non-existence in 1915 that was the
first indication that Einstein's relativity ideas were right.

Now, 83 years later, Vulcan has return - again theoretically - but in the
form of a belt of smaller bodies dubbed Vulcanoids. The theory suggests that
a belt of hundreds of Vulcanoids (rocky asteroids less than 25 kilometres in
diameter) could be still undetected in a ring around the sun. They would be
less than half Mercury's distance from the sun and because of their small
size would have remained unseen.

Searches for Vulcanoids during total eclipses of the sun, when the sun's
brightness is vastly reduced, have never picked up such tiny objects. Now
astronomers are turning to a novel search technique - jet fighter planes.

Dan Durda and Alan Stern, astronomers at the Southwest Research Institute in
Boulder, Colo., have taken an advanced digital camera designed for
astronomical measurements from the space station and adapted it to the back
seat of an F-18 U.S. air force fighter jet on loan for scientific research.
The jet is flown to its maximum altitude (12 kilometres) in twilight over
the Mojave Desert.

"This gives us a view of a dark sky much closer to the sun than can be
obtained at any mountaintop observatory on Earth," explains Durda. "The only
way we could see more clearly is with the Space Telescope but its optics
would be damaged if it were ever pointed this close to the sun."

Durda and Stern are now analyzing their observations, which they say
constitute the most detailed search for Vulcanoids ever conducted. They hope
to present their results at a scientific meeting later this year.

If they do find something - anything - inside the orbit of Mercury it will
upset current ideas of the history of that part of the solar system. In its
youth, the sun seems to have been a bit of a hothead, blasting off bursts of
hot gas intertwined in ropelike magnetic fields. This probably cleared out
the entire region between the sun and Mercury, a zone Carl Sagan once called
"Vulcan's hammer." Mercury itself appears to have been cooked down to a
shrunken size by this process, too. If anything remains, and Durda and Stern
find it, our thinking about this region may be turned on its head.

------
Terence Dickinson is editor of Skynews magazine and the author of several
books for backyard astronomers

Copyright 2002, The Toronto Star

================
(4) EARTHQUAKE FORECASTING: SATELLITE SYSTEM MAY PROVIDE WARNING

>From Space.com, 12 July 2002
http://www.space.com/scienceastronomy/earthquake_watch_020712.html

By Leonard David
Senior Space Writer

Earth's got the shakes. What's worse is that the ripple effects from those
shudders -- in the form of earthquakes -- kill thousands each year and cause
billions of dollars in damage.

Scientists are looking into a satellite system that can spot the stresses
and strains of looming earthquakes, perhaps providing short-term forecasting
of the vicious events.

On June 22, a strong quake, registering 6.1 Richter scale struck northern
Iran, killing and injuring hundreds of people and destroying dozens of
villages spread across a mountainous rural area. On Thursday, northern
Taiwan was rattled by an earthquake and in Sydney, Australia, public
authorities there were recently surprised to find an earthquake fault line
next door to the projected construction site of an expensive nuclear
reactor.
 
Meanwhile, a new study by the largest disaster relief organization -- the
International Federation of Red Cross and Red Crescent Societies -- calls
for early warning systems to help avert human and economic losses from
Mother Nature's nasty knock-out punches, be they from earthquakes,
hurricanes, floods or droughts.

Taking out the GESS work

Congress allocated $2 million in 2000 to NASA, kick-starting an assessment
of how space technology can be on the lookout for imminent earthquakes. The
outcome is the Global Earthquake Satellite System (GESS) study.

What has scientists excited is the advent of satellite synthetic aperture
radar interferometry. That's a mouthful but also labeled simply as InSAR.
The technique has proven revolutionary.

InSAR relies on image pairs to derive displacements to the resolution of
radar wavelength. Topography changes can thus be observed, like crustal
deformation, particularly when combined with continuous Global Positioning
System (GPS) satellite arrays.

Boosting confidence in the idea is radar data churned out by European Remote
Sensing Satellites. ERS-1 and ERS-2, respectively launched in 1991 and 1995,
clearly revealed complex deformation fields of many earthquakes. ERS sensors
gathered evidence of stress transfer and earthquake triggering between
neighboring faults in southern California.

Multi-year roadmap

The GESS study focuses on a dedicated InSAR system. Having the hardware in
orbit would lead to greater understanding of earthquake physics and better
earthquake hazard assessments, said Carol Raymond, a geophysicist at the Jet
Propulsion Laboratory in Pasadena, California. She is leading the GESS study
effort.

Now underway, Raymond said, is production of a 20-year roadmap for
earthquake monitoring from space. "We have focused our efforts on
interferometric synthetic aperture radar techniques as these appear most
promising," she told SPACE.com.

A first step is placing in low Earth orbit a single "pathfinder" mission
that is optimized for earthquake studies. That would be followed by a set of
satellites operating at low altitude, orbiting in such a way as to maximize
coverage. Finally, a small constellation of higher altitude spacecraft would
churn out higher quality data and have operational flexibility, Raymond
said.

Up and operating, when?

Some of the GESS study is directed towards technology development. Large
deployable antennas and advanced processing systems are under review, as is
coming up with ways to enhance remote sensing of Earth from space.

GESS study members are also looking into other types of measurements.
Susceptibility of terrain to shaking, liquefaction hazards, landslide
vulnerability are part of the review. Possible precursory signals to a quake
are being studied too, such as changes in Earth's magnetic field; enhanced
heat flow in the ground; even reported flashes of light. These types of
phenomenon could be forewarning indicators.

How soon could GESS be up and operating?

The high-orbit, high-performance radar mission could be launched within a
decade, perhaps less, given funding, Raymond said. "The low Earth orbit
constellations are absolutely doable now if funds were allocated," she said.

Flashing yellow

Earthquake prediction is a tough assignment, contrasted to forecasting, said
Paul Lowman, a geophysicist in the Geodynamics Branch at NASA's Goddard
Space Flight Center in Greenbelt, Maryland.

"If you're doing earthquake prediction, you've got to come up with time,
place, and magnitude. If you miss any one of those three, you haven't really
made much of a prediction," Lowman told SPACE.com.

The approach now, Lowman said, is picking a specific area and give some idea
of the probability of a sizeable quake within some reasonable time frame.

Lowman is author of the long awaited tome, Exploring Space, Exploring Earth.
The book is set for release this August by Cambridge University Press and
details the extraordinary findings about Earth gleaned from decades of space
research.

The combination of orbiting hardware, novel space geodesy techniques, GPS,
and a range of airborne and ground gear is a potent new way to study
earthquakes, Lowman said. "You should be able to focus on areas from space
that you might say would be flashing yellow. That means you better take a
harder look at those places and get there with ground equipment," he said.

Swaying public attention

Considerable attention is paid to "interplate" boundaries in regions like
Southern California, and other spots around the Ring of Fire of the Pacific
Ocean basin. These areas are where the edges of tectonic plates collide, and
are marked by concentrations of earthquakes.

But attention should also be paid to "intraplate" tectonics too, said Jacob
Yates, a scientist within NASA Goddard's Geodynamics Branch. He along with
Lowman point out that some of the most catastrophic earthquakes on record
did not occur along plate boundaries.

Yates and Lowman see GESS as instrumental in monitoring intraplate activity,
especially in remote regions of the world. Unfortunately, many of the most
devastating earthquakes of the 20th century occurred at the intraplate level
in Third World countries, Yates told SPACE.com.

Intraplate earthquake areas deserving of study include the Hudson Bay,
Australia, the Ural Mountains, and the Aegean Sea. Understanding intraplate
earthquakes would be a very effective use of the GESS mission, Yates said.

More complicated than science

A co-investigator on intraplate crustal dynamic study for GESS, Yates said
that space radar technology has matured greatly over the years.

"It's time to take the next step at looking at vertical and horizontal
motion from InSAR to determine crustal motion. I'd say that InSAR is the way
to go for monitoring sudden changes in crustal motion that may be precursors
to seismic motion or volcanic activity," Yates said.

While GESS would operate around the clock, Lowman said, there's no doubt
that even forecasting earthquakes will not be easy. Great care must be taken
in not issuing false alarms.

"I think, eventually, we'll get to the point where earthquakes can be
predicted. But even today, it's going to be years down the road," Lowman
said.

Then there's the need to provide GESS-generated data in a timely manner to
responsible governments and agencies. That is key if government-driven
disaster preparedness and planning is to be successful.

"It gets much more complicated than just science," Lowman said.

2002 SPACE.com, Inc.

================
(5) "CONTAMINATION RULED OUT": INDIAN SCIENTISTS CLAIM TO HAVE FOUND AMINO
ACIDS IN METEORITE

>From Indo-Asian News Service, 13 July 2002
http://news.eians.com/2002/07/13/science-index.html

New Delhi, July 13, -- The discovery of amino acids, the building blocks of
life on Earth, in a meteorite that crashed in India's desert western state
of Rajasthan has reaffirmed the hypothesis that life originated in outer
space.
                                           
Scientists in Jodhpur claim they discovered three amino acids --
Phenylalaine, Tyrosine and Tryptophan -- for the first time in the
Didwana-Rajod meteorite that crashed near Didwana, in the Nagaur district in
1999, reported Indo-Asian News Service (IANS) on Saturday.

"Soon after the Didwana-Rajod meteorite fell, we started a detailed study of
the composition. Our findings show this meteorite was very different from
others that have fallen in the region," said  B.S. Paliwal, head of the geology
department in the Jai Narain Vyas University, Jodhpur in Rajasthan.         

Vinod Tewari of the Wadia Institute of Himalayan Geology in Dehradun in the
newly created Northern Indian State of Uttranchal, who conducted experiments
on the meteorite, said, "Amino acids found in the meteorite are
extraterrestrial and any ground contamination has been ruled out."               

Paliwal said, there are two theories about origin of life on Earth: one
suggests life originated on the planet and the other that it was transported
to it from outer space by meteorites that crashed on to its surface.

"Amino acids are building blocks of life and their presence in   
meteorites suggests organic compounds were derived from proto-       
planets," said Paliwal.                                              

A proto-planet is a planet-to-be that draws from the cloud of gas and dust
around it. Scientists suggest most proto-planets have hydrogen, helium with
trace amounts of methane and ammonia in gaseous form in a dense atmosphere
enveloping the rocky cores of the inner planets.


Some of these elements are the basic minerals required to form amino acids.


Paliwal said, "Age-wise, this meteorite is younger than Earth, but quite
older than the separation of the moon. Presence of amino acids on the
meteorite as old as 4.5 billion years is quite significant has important
implications on the origin of life in the universe."       

He said the discovery supported the theory that bio-molecules and bacteria
exist in outer space and microbial life was transported to Earth by
meteorites, asteroids and comets.                           

The findings have been published in latest issue of the Journal of
Geological Society of India.                                         

============================
* LETTERS TO THE MODERATOR *
============================

(6) THAT NIGHT IN TEL AVIV

>From Richard Clark <rclark@lpl.arizona.edu>

Jiri Borovicka <borovic@asu.cas.cz> wrote (CCNet, 12 July 2002):

>Richard Clark <rclark@lpl.arizona.edu> wrote (CCNet, 11 July 2002)
>>      During the Gulf War an upper stage from a
>> recent Russian launch reentered on a track that took it over
>> Israel. It did not trigger a response from Israel. A study of this
>> event would be useful.
>
> I think that the reason for no response could be that the object (Kosmos
> 2122 B) came from wrong direction. By chance, the re-entry of this rocket
> body was photographed by 6 fireball cameras operated by our institute. Part
> of the trajectory stretching from Poland to Romania at the altitudes from 80
> to 60 km, when the ablating object had visual magnitude of about -9, was
> captured. This certainly was not the direction from Iraq.

Hi Jiri and Benny,

Thanks very much for the information and references Jiri. I had not been
able to find much information on this yet.

At the time I posted I was unclear on what object had reentered. I thought
it was the Progres rocket body, which entered on the 15th. But it was from
the Cosmos launch, which entered on the 18th. On reviewing the chronology of
the war there are a couple of items I neglected in my original post.

By the time of the entry (the 18th) Isreal had already been hit by several
scuds, and was already under intense pressure from the US to withold its
response. So the entry was just one more event for Isreal to not respond to.

Also, the first patriot batteries were not deployed to Isreal until the
19th. I do not know how much space surveilance capability Isreal's defense
establishment had at that time. Anti aircraft radar would not normally
provide much coverage at near orbital heights. However, with the much
heightened state of alert, and especially after the numerous scud attacks,
this may have changed.

Under the circumstances I suspect the direction of travel of the entry was
of relatively little importance to the immediate perception of the event, at
least in the field. When confronted with unusual situations and sightings,
especially under time of stress, humans generally are lousy observerors.

Even though Isreal was already under pressure to "please don't get involved
and break up the coalition", it would still be instructive to study (if such
is possible) how this event was observed and perceived in the field,
communicated through official and unofficial channels, and analyzed at
various levels by allied commanders and leaders. This is the closest that I
know of to a simulation of an actual politically sensitive impact. It isn't
really all that close, but is still worth examining to learn what we can
from it.

Another thing I noted from that first week of War news was that when the
entry was reported in the West, or at least in the local US papers I saw, to
the extent that it was mentioned, it was generally treated as somewhat of a
novelty item.

Richard Clark
rclark@lpl.arizona.edu

=============
(7) I DON'T THINK WE NEED TO NUKE ASTEROIDS

>From Konrad Ebisch <kebisch@lgc.com>

Dear Benny,

I am seeing on CCNet a lot of talk about nuking planetoids to change their
orbits, or, if it is very late, to blow them up. Plus exotic ideas like
attaching solar sails. Yet, having read CCNet for a good while, I can't help
but think that this is not the solution to most of the threat. 
I note that the avowed goal of finding 90 percent of the 1 km objects
implied that meeting most of the threat is an accepted target. 

The threat comes in two parts, asteroids and comets. 

Asteroids that threaten the earth are on orbits that will mean that they
will come at us repeatedly.  The one that missed us last month will come by
again and again, and if we are unlucky it will impact in June of some future
year.  This repetition, and the fact that Earth is a small target, mean that
most such objects can be found many years ahead of the impact. 

Further, a very small push, a long time ahead, will slightly change the
distance of a future near miss.  Suppose we calculate that the body that
just missed us in June 2002 will have near misses in June 2022, June 2042,
and June 2062, followed by an impact in June 2082. So we send a probe to
intercept it, giving it a very small push. The miss distance in 2022 is
changed slightly, so the perturbation by Earth's gravity is different. Thus
the distance is changed even more in 2042, and more still in 2062, with
greater changes in the perturbations. A very small push, followed
by the multiplier effect of one or more near misses, can make a significant
orbit change, turning the impact into a miss.  We should not need nukes for
this. The problem looks quite solvable for the great majority of asteroid
threats. 

Comets I have not seen much in the last few CCNets. These are the ones that
seem more likely to surprise us.  Let's worry more about these. Perhaps this
IS a place for the nukes. If it turns out that a comet nucleus really is a
pile of dirty snowballs, would it evaporate quickly if we blew it apart,
exposing the little pieces to sunshine? 

One more thing that seems counter-intuitive to me. There seems to be an
opinion that small objects (10 meter? 1 meter?) will burn up harmlessly in
the atmosphere. While one of these would not destroy a city, I'd hate to
have it hit my house. And shouldn't there be a lot more of these than the
big ones?  Do we have records of impacts? 

I imagine a 10-meter or 1-meter iron ball coming at many km/sec. Just how
much protection is our atmosphere? Yes, it's 200 km thick.  Well, yes, the
part that the bullet would begin to feel is 50 km thick. But if it were all
compressed to sea-level density, it would be maybe 5 km thick.  And if it
were condensed to the density of that iron ball, it would be maybe 6 meter
thick.  Somehow, I don't feel safe, when threatened by a projectile at so
high a speed, behind such thin armor. I would like to see a good computer
model of a 1-meter or 10-meter iron ball coming through at such a speed.  My
gut feeling would suggest that some ablation would occur, but it would still
make a pretty crater.  Just how large an object is needed to blast through
out atmosphere? 

Konrad Ebisch

=================
(8) OF DRAGONS AND OTHER MATTERS: REPLIES TO MELFYN THOMAS'S COMMENTS, CCNET
63/2002 - 24 MAY

>From Alastair McBeath <vice_president@imo.net>

Dear Benny,

Melfyn Thomas's remarks in CCNet 63/2002 (24 May) raise a number of points
in need of discussion, plus there are some corrections to make to comments
he attributes to my CCNet 45/2002 (8 April) message.

Contrary to Melfyn's concern about my supposed misinterpretation of his
colleague John Michael's notes in CCNet 39/2002 (22 March), I made no
dispute that the common current and past Welsh usage of "draig" includes
meteoric and meteorological phenomena, and I am naturally familiar with the
lists of meanings for "draig", "dragon", and other spelling/word variants
Lofmark (1995: 44-5) provides, drawing on two leading Welsh authoritative
dictionaries. Indeed, I mentioned many of the meanings for these terms in my
earlier CCNet notice, and drew attention to the fact that the
meteoric/meteorological ones seem never to have been among the most
important.

Regarding Melfyn's comments that I gave "the date 537 as referring to a
siting [sic] of a celestial object (probably a comet)", this is quite
incorrect. My sole reference to 537 AD was as the dating for the death of
Arthur given in "The Welsh Annals" - see (Morris, 1980: 44-9). Perhaps
Melfyn has assumed I wrongly gave the anagrammatic date of 735 AD for what
was probably a very bright, acoustic fireball from the Irish annals, but 735
is accurate from the source used (McCarthy & Breen, 1997). Melfyn then goes
on to ally this nonexistent reference of mine with a comment in Low's
abridgement of Gibbon's "Decline and Fall" about a comet in 537 (Gibbon,
1960: 580-1). This text has cropped up several times recently in CCNet
messages, but nobody seems to have pointed out that while it is a
wonderfully evocative read, its historical accuracy is poor in places, and,
more importantly, it is not a primary source, although it seems to have been
treated as if it were. I note Mike Baillie (CCNet 64/2002 - 30 May)
helpfully corrects the dates to 531 and 539 for the two (not one) comets
cited by Gibbon, suggesting the 531 comet was Halley's. There is some
confusion among the surviving European texts which mention a comet around
this time, most of which were written only long after the event (between the
late 6th to early 12th centuries), yielding dates for the comet from 530-2
AD. Chinese records in conjunction with modern computations indicate
Halley's Comet returned in 530 AD; the Chinese observed it from August 29 to
around September 26 or 27, moving south-east from Lynx to Libra during that
time (Ottewell & Schaaf, 1985: 23 and 138-9). The 539 AD comet seems to be
mentioned chiefly by Procopius ("History of the Wars", II.IV: 1-3) in
European sources, who notes no comet in c.530-2. Procopius's description
suggests it was first visible in the morning sky in Sagittarius at some
stage between late December 539 to early February 540, and was seen for more
than 40 days, although Chinese sources only mention a notable comet passing
from Sagittarius to Aries between 539 November 17 to December 1, in the
evening sky.

>From his 537 AD date, Melfyn next mentions that this "is also the date given
generally to the year of birth of the poet Myrddyn (Merlin of Arthurian
myth)", though regrettably without noting down his source for this
remarkable proposition. Mike Baillie, by comparison, wants Merlin to die in
536 AD (Baillie, 1999: 192-4)! In neither case can this be credibly
correlated with the report of Merlin going mad in 573 AD according to the
"Welsh Annals" (Morris, 1980), especially if he was still a youth at the
time, as other Welsh traditions indicate.

There are a number of reasons why the Britons (technically not the Welsh at
this period; "Welsh" as a separate population identity seems to begin
emerging only around the mid 7th century - cf. (Lofmark, 1995: 44)) might
have preferred the dragon as a military emblem after the Roman fashion, and,
contra Melfyn's notes, I made no earlier comments regarding any paucity of
rationales concerning this matter. Lofmark (1995: 40-3 and Fig. 11, p. 35)
ably covers much of this subject, with the appropriate references. To recap,
by the 3rd century AD, the draco standard was used by the Roman cohorts,
whereas the aquila standard remained the emblem of the legion. Each legion
was composed of ten cohorts, thus the draco was ten times as numerous as the
aquila. As Roman power in Britain declined in the centuries before their
final withdrawal, military units here operated increasingly as cohorts, not
legions, making the aquila a still rarer - perhaps even nonexistent - sight.
Add to this that the non-legionary troops, the auxilia, which made up half
or more of Britain's garrison, were normally organised only as cohorts -
especially the infantry and mixed cavalry-infantry units - and there is the
potential for a lot of draco standards about generally. The draco was much
larger and more impressive than the aquila too. Estimates from period
artwork coupled with archaeological finds suggest the draco was around 1.5-2
m long (mostly consisting of a brightly coloured cloth "windsock" body),
with a cast metal, often canine, head roughly 20-25 cm across, while the
cast metal aquila was generally about 25-45 cm in size. Both were borne on
tall poles, probably gilded. As various texts attest, the draco loudly
hissed, howled or whistled as the wind passed through it, and several
authors comment on the aura of fear this generated in enemy troops. Draco
standards are often described as if they were alive, and it may be they were
thought sometimes to be living dragons. The draco seems to have become
associated with the Emperor during the 4th century (e.g. Constantius II, 357
AD), if not sooner, which would further strengthen the reasons why a notable
leader might choose to be represented by a dragon. Given that there are no
surviving references to a belief in meteors being called dragons before the
widespread use of the draco-style standard (not simply by the Romans and
Britons, but among other European and Near-Eastern armies of the early
centuries AD), coupled with the familiar, bright, mobile nature of the draco
in use, it seems more likely meteors should have acquired their draconic
title from the use of the military emblem. The rough similarity in physical
appearance between, particularly brighter, meteors and comets most likely
led to comets occasionally being described as dragon-like, i.e. like a
meteor, which was itself like and called after the dragon standard. This
seems to work significantly better than having a comet, a remote, rare,
unpredictable, nocturnal, and generally feared object, being reconfigured as
a dragon before being adopted as a proud, beneficial, common, military
symbol. It also fits far better to the surviving textual evidence, where
historical records exist of draco standards being used by opposing European
and Near Eastern armies in Roman through to early medieval times, as well as
in other period literature, such as the battling red and white dragons used
symbolically to represent the Britons and Saxons in the "History of the
British" (cf. (Lofmark, 1995: 46-7) or (Morris, 1980: 30-1)).

I'm surprised Melfyn thinks the dragon played only "a very minor role in the
rest of Celtic mythology", though this may depend on just what his
definition of "Celtic" is. I follow James MacKillop's view here, that old
texts and oral tales can be considered "Celtic" if they were originally in
Irish or Scottish Gaelic, Manx, Welsh, Cornish or Breton (MacKillop, 1998:
xiii-xxvii). For those unfamiliar with Celtic myths, or who may find
sourcing pointers helpful, this is a valuable, well-referenced work. I have
already carried out an overview of dragons and draconic beasts in Celtic
literature (McBeath, 2001). In brief, Celtic dragons come in a variety of
guises, and are quite frequently ill-described. They have a penchant for
watery habitats (such as lakes, pools, rivers or the sea). The Welsh ones
are more often winged (which probably helps account for the belief in living
winged serpents still current in parts of Wales into the early 20th century;
cf. (Simpson, 2001: 40-1, and refs.)), and sometimes breathe fire, whereas
those from Ireland and Scotland are more typically serpentine, even so being
capable of feats a living snake would find impossible. In character, the
Gaelic dragons are generally malevolent, sometimes blending into the malign
water horses and monsters of the same regions, whereas the Welsh ones may be
more equally malefic or benefic, the latter in-keeping with the positive
dragon = leader epithets I discussed previously on CCNet, as well as the
luck-bringing nature of some of the Welsh winged serpents.

"Pendragon" (and its variants) is thoroughly discussed by Lofmark (1995:
43-52 and references), appearing in early Welsh literature as an epithet for
any great warrior, not necessarily some single, powerful warlord, as Melfyn
intimates. It does not feature in the works attributed to Nennius from
around the early 9th century, while Geoffrey of Monmouth's inventiveness in
the early 12th century increased its status. Although the earliest records
which call warriors "pendragon", "draig", etc., probably originated in the
mid to late 6th century ("dragon" is attested as one of several rather
negative animal epithets used by Gildas in his "Ruin of Britain", c.540 AD -
see (Winterbottom, 2002: line 33.1)), when it first appears, it is used as
if it were a commonly understood title. This implies an earlier origin prior
to the surviving texts, which would be consistent with the British adoption
of the Roman draco standard during the 5th century, or before, a period for
which there are regrettably no surviving British sources covering this
matter.

Melfyn then returns to Myrddin, quoting from Geoffrey of Monmouth's "Vita
Merlini" (c.1149), which quote concludes with a description of a lance and
spear-armed force in the sky, typical of what is generally thought to be a
medieval description of the aurora borealis, as I mentioned in my 8 April
message. As I also mentioned there, Geoffrey is an unreliable historical
source for the topics he covered, though in this context he is notable for
the almost single-handed creation of the Arthurian Merlin, by drawing on
separate tales of Lailoken (a c.6th century prophetic wild man of the woods
from northern England/southern Scotland, an area roughly equivalent to
modern Cumbria and its immediate surrounds in England north into the
Southern Uplands of Scotland and Strathclyde), Myrddin (a probably fictional
c.6th century British poet/prophet, perhaps based on tales of Lailoken), and
Ambrosius Aurelianus (in Welsh, Emrys Wledig, a historical 5th century
British commander in Gildas and the "History of the British", possibly
originally two men - father and son? - who later became conflated into one.
Emrys/Ambrosius features in the "History of the British" separately as the
boy able to derive the meaning of the combative red and white dragons for
Vortigern, and it is this prophetic Emrys Geoffrey uses in "his" Merlin).

The passage from the third of the "Four Branches of the Mabinogi" Melfyn
quotes is one of two instances in "Manawydan son of Llyr" where a loud noise
and a fall of mist results in the magical vanishment of people, animals and
buildings from Dyfed, south-west Wales, although naturally, the place where
the hero of the tale, Manawydan, is, himself and any followers with him, are
not so affected. The story revolves around him magically solving the puzzle
of what has happened, and when he finally does so, seven years after the
first event, everything is returned to exactly how it was before it all
disappeared. The "Mabinogi" manuscripts were probably constructed in their
surviving forms between the mid-11th to mid-12th centuries, drawing on
various earlier oral renditions, although the complete texts as we have them
are from the later "White Book of Rhydderch" (c.1325) and the "Red Book of
Hergest" (c.1382-1410; this is the preferred text for most modern
translations). Given the repetition of elements in these magical vanishments
elsewhere (e.g. bang, cloud of smoke), and with time-dilation effects
typical of much faerie-lore involved, it is difficult to be sure if any
serious credence should be given to the idea that the descriptions in this
tale were ever historical events, however dimly-recalled some 600-odd years
later (about as distant in time then as we are today from Chaucer),
especially as Celtic tales nearly always include some fabulous elements.

Finally, Taliesin (tal = forehead, brow; iesin = beautiful, radiant). There
are effectively two Taliesins. One was a probably historical bard, thought
responsible for around a dozen surviving poems, who lived chiefly in
northern England/southern Scotland, a region similar to that I noted above
concerning Lailoken, in the late 6th century, a similar figure to another
great bard from the same area who probably lived also around 600 AD, Aneirin
(most famous modernly for his elegiac poem "Gododdin"). The second Taliesin
is a construct of probably some memories of the historical figure, conflated
with much popular folklore and literary invention, including scores of poems
(some of which may have originated as early as the 9th century), that became
attached to his name before the "Hanes" or "Ystoria Taliesin" was compiled
in its known form during the mid-16th century. This legendary Taliesin
became a powerfully magical, superhuman, ubiquitous, being. Consequently,
the "Hanes Taliesin", along with the numerous poems attributed to this
"other" Taliesin, cannot be considered historical or mythological texts
relevant to the 6th century. In particular, the 1849 translation of the
"Hanes Taliesin" by Lady Charlotte Guest should not be used for critical
interpretations, as it partly draws on manuscripts "discovered" in the late
18th/early 19th centuries by a notable, if highly-talented, forger.

References:

Baillie, M., 1999, "Exodus to Arthur: Catastrophic Encounters with Comets",
B. T. Batsford, London.

Gibbon, E., 1960, "The Decline and Fall of the Roman Empire: An
Abridgement", Chatto and Windus, London (abridgement by D. M. Low based on
the 1854-55 version).

Lofmark, C., 1995, "A History of the Red Dragon", Gwasg Carreg Gwalch,
Llanrwst.

MacKillop, J., 1998, "Dictionary of Celtic Mythology", Oxford University
Press, Oxford & New York.

McBeath, A., 2001, "Dragons in Celtic Tales", The Dragon Chronicle 21, pp.
7-16.

McCarthy, D., A. Breen, 1997, "Astronomical observations in the Irish annals
and their motivation", Peritia: The Journal of the Medieval Academy of
Ireland 11, pp. 1-43.

Morris, J. (translator), 1980, "Nennius: British History and the Welsh
Annals", Phillimore, Chichester.

Ottewell, G., F. Schaaf, 1985, "Mankind's Comet: Halley's Comet in the past,
the future, and especially the present", Astronomical Workshop, Greenville,
SC.

Simpson, J., 2001, "British Dragons" (2nd edition), Wordsworth Editions &
The Folklore Society, Ware & London.

Winterbottom, M. (translator), 2002, "Gildas: The Ruin of Britain and Other
Works" (new edition), Phillimore, Chichester.

Alastair McBeath

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