CCNet 79/2002 - 8 July  2002

"Only two days before a Space Roundtable at the United States Senate
will address "The Asteroid Threat", an atmospheric impact on July 4
(Independence Day) has set off a timely reminder that the impact
hazard is not limited to large objects. Last Thursday, Israeli officials
reported that a missile may have exploded a few miles from an EL-AL plane
flying over the Ukraine. Over the weekend, however, both the Ukrainian
Defense Ministry and Ukraine's National Space Agency indicated that a
meteor rather than a terrorist attack may have been the cause of the
atmospheric fireball explosion.... The latest incident should serve as a
catalyst to begin addressing the political, economic and security risks due
to smaller NEOs, a perpetual threat that has been neglected for far too
--Benny Peiser, 8 July 2002

    Benny Peiser <>

    CNN, 6 July 2002

    BBC News Online, 6 July 2002


    YOWUSA, November 2001


    Michael Paine <>

    Peter Haines <>


>From Benny Peiser <>

Only two days before a Space Roundtable at the United States Senate will
address "The Asteroid Threat", an atmospheric impact on July 4 (Independence
Day) has set off a timely reminder that the impact hazard is not limited to
large objects.

Last Thursday, Israeli officials reported that a missile may have exploded a
few miles from an EL-AL plane flying over the Ukraine. The alarm was given
added credibility as pilots of two other planes flying over the same region
also reported seeing a fireball at the same time that resembled a missile
explosion. Given the current war on terrorism, given that an Israeli
passenger plane was shot down by a Ukranian missile last year killing 78
people, given the symbolic date of the incident and the fact that an
Egyptian immigrant killed 2 people at an El-Al ticket-counter in a terrorist
attack in LA on the same day, it seemed not too far-fetched to conjecture
that the Ukranian fireball was due to another missile attack.

Over the weekend, however, both the Ukrainian Defense Ministry and Ukraine's
National Space Agency indicated that a meteor rather than a terrorist attack
may have been the cause of the atmospheric fireball explosion. Whatever the
final result of the investigations may confirm, it is evident that a
meteoric fireball can easily be misjudged as a terrorist attack - in bigger
cases even as a nuclear first strike.

A number of NEO researchers (including myself) have become increasingly
concerned about the largely neglected risks of small impacts on global
security and economic and political stability (see interviews with Brian
Marsden and Pete Worden attached below). In the wake of September 11, these
concerns have focused primarily on small, Tunguska-sized impacts and their
aptitude for being mixed up as nuclear first strikes. The latest incident
shows unmistakably that even smaller atmospheric impacts (not to mention the
probability that a plane, one day, may be brought down by a meteor strike).

The latest incident should serve as a catalyst to begin addressing the
political, economic and security risks due to small impacts, a perpetual
threat that has been neglected for far too long.

Benny Peiser
CCNet Moderator
Liverpool John Moores University


>From CNN, 6 July 2002

Meteor may have alarmed Israeli pilot

KIEV, Ukraine (AP) -- A meteor may have caused the flash that alarmed an
Israeli pilot flying over Ukraine, Ukrainian officials said Saturday,
insisting it was not a missile.

An El Al pilot reported seeing a missile fired from the ground over central
Ukraine during a Tel Aviv-Moscow flight on Thursday night. Israeli officials
said the missile exploded a few miles from the plane.

Pilots of two other planes flying over the Dnipropetrovsk region reported
seeing a big blue fireball that resembled a missile explosion at the same
time, the ITAR-Tass and Interfax news agencies cited Ukrainian aviation
officials as saying Saturday.

The incident was a sensitive issue in the Ukraine because in October, an
errant missile fired from a Ukrainian military base shot down a Russian
plane, killing all 78 people on board, most of them immigrants to Israel.

On Saturday, the Ukrainian Defense Ministry issued a statement saying that
no missiles had been fired in the area that night and that the pilots may
have witnessed a meteor entering the Earth's atmosphere.

Officials from Ukraine's National Space Agency also suggested a meteor could
have been the culprit, as did Yaroslav Skalko, deputy chairman of Ukraine's
civil aviation department, ITAR-Tass and Interfax reported.

"The airplane crews who saw over Ukrainian territory on July 4 a flash that
resembled a missile explosion were observing phenomena of unidentified
origin not related to the activities of the Ukrainian armed forces," the
Defense Ministry statement said.

The ministry said the stocks of missiles and other long-range ammunition
have been inspected and nothing is missing, according to ITAR-Tass and

Ukrainian President Leonid Kuchma said Friday that no missile-firing
exercises had been held in Ukraine since the October crash.

Israeli officials were especially concerned about the incident because it
came the same day that an Egyptian immigrant shot and killed two people at
the El Al's ticket counter at Los Angeles International Airport.

Copyright 2002 The Associated Press. All rights reserved.


>From BBC News Online, 6 July 2002

'Meteor' caused Israeli plane alert

Ukrainian officials say the "strong flash" reported by the pilot of an
Israeli plane over Ukraine on Thursday was probably caused by a meteor
entering the atmosphere.

In a statement on Saturday, the Ukrainian defence ministry said no missiles
had been fired in the area at the time.

The pilot had reported seeing what he believed to have been a missile
exploding in mid-air at a distance from his aircraft.

Last year, 78 people died when a Russian airliner flying from Israel was hit
over Ukraine by what was believed to have been a stray missile fired during
a military exercise.

The Israeli Government said the El Al plane was never in danger during the
latest incident.


"Specialists with the Ukraine Space Agency have concluded that it was
probably a light phenomenon resulting from a meteor's entry into the earth's
atmosphere," Ukraine defence ministry spokesman Kostyantyn Khivreno told AFP
news agency.

Mr Kvirenko said the Ukrainian forces had "nothing to do with this".

"We have checked all our missiles, and I can tell you they are all there,"
the AFP quoted him as saying.

"The airplane crews who saw over Ukrainian territory on July 4 a flash that
resembled a missile explosion were observing phenomena of unidentified
origin not related to the activities of the Ukrainian armed forces," the
statement said.

Thursday night's reported incident occurred during a regular El Al flight
from Tel Aviv to Moscow.

The pilot saw a "strong flash" at a distance while flying over
Dnipropetrovsk in Ukraine, El Al said.

A Russian pilot, flying a Urals Airlines plane, told Ukrainian air traffic
controllers that he had also seen a strong flash, according to AFP news


But Ukrainian President Leonid Kuchma said the suggestion that the incident
involved a Ukrainian missile was "absurd".

A Ukrainian missile caused last year's plane crash
"After last year's unfortunate incident, firing missiles is totally banned
in Ukraine," he said.

In October last year, a Tu-154 plane operated by Sibir airlines flying from
Tel Aviv to Novosibirsk in Siberia exploded in mid-air over Ukraine, before
crashing into the Black Sea.

All those on board - most of them Israelis - were killed.

After repeated denials, the Ukrainian defence ministry conceded that one of
its ground-to-air missiles had brought the aircraft down.

Copyright 2002, BBC


ProSpace, in conjunction with Space Frontier Foundation, is pleased to
announce the ninth in our series of Space Roundtables at the United States
Senate. Titled "The Asteroid Threat: Identification and Mitigation
Strategies", this program will explore a range of ideas and information
regarding the asteroids and other objects that cross the earth's orbit, what
we are doing to find and track them and what we could be doing to protect
the earth from a devastating impact.

The program will be held on Wednesday, July 10th at 1:00pm in room 192 of
the Dirksen Senate Office Building. To attend, please RSVP to: Include your name, affiliation and telephone number.

You may be aware of the several close passes we have seen this year by large
asteroids. The last such object, classified "2002MN", passed within 75,000
miles of the earth at a speed of 23,000 miles per hours just over one week

This object was approximately 70-100 meters in diameter, making it similar
in size to an object that hit the Tunguska region of Siberia in 1908. That
impact resulted in a blast equivalent to 10-15 megatons, leaving an area of
devastation that would cover two-thirds of Rhode Island.

While the idea of such an occurrence has been the stuff of science fiction,
events such as Tunguska and our recent close calls dictate we take a hard
look at the science facts. The experts we are gathering for our event will
present detailed information on search efforts, warning systems, possible
diversion scenarios and the overall probabilities that we will experience
such an event.

Our panelists for the program include:

Brig. Gen. Simon P. Worden, USAF
US Space Command

Dr. Colleen Hartman

Dr. Thomas Morgan

Dr. Brian Marsden
Minor Planet Center
Harvard-Smithsonian Center for Astrophysics

Evan Seamone
University of Iowa College of Law

Dr. Lee Valentine
Space Studies Institute

Rick Tumlinson

Rich Godwin
The Watch

You are cordially invited to attend the program, as well as the buffet lunch
that will precede it. Simply RSVP via email at: When
RSVP'ing, please provide your name, affiliation and your phone number.

See you at the Roundtable!

Marc Schlather
Executive Director
The Space Roundtable

Theme Near Earth Asteroid Threat Date Wednesday, July 10, 2002 Location Room
192 Dirksen Senate Office Building, Washington, DC, US Web Address Contact


>From YOWUSA, November 2001

Exclusive YOWUSA Interview With Dr. Brian Marsden, Associate Director of the
Smithsonian Astrophysics Observatories Reveals a New and Frightening
Post-911 National Security Risk

YOWUSA.COM, November 10, 2001
Marshall Masters

During a joint news conference with French President Jacques Chirac last
Tuesday, President Bush warned the world of the specter of a nuclear
catastrophe as a result of Osama bin Laden's likely acquisition of nuclear
weapons from maniacs like Iraqi strongman Saddam Hussein  Further, The
Sunday Telegraph (London) just published an article regarding new evidence
that Iraq was struck 4000 years ago by a 150-meter meteorite which begs the
question: Should an unexpected meteorite impact event happen in the Middle
East today, could it trigger a nuclear exchange given the present
instability in the region?  According to Astronomer Dr. Brian Marsden, it
could, and that our chance of detecting a 150-meter meteorite prior to
impact in a region like the Middle East is "somewhere between none and dumb

Interview with Dr. Brian Marsden

In this November 6, 2001 telephone interview between Marshall Masters of
YOWUSA and Dr. Brian Marsden, Associate Director of the Smithsonian
Astrophysical Observatory, the possibility that an unforeseen impact event
could be used a pretext by international terrorists to start a global
nuclear holocaust was examined.

MARSHALL MASTERS: President Bush has just warned the world that Osama bin
Laden is working to gather weapons of mass destruction including biological,
chemical and nuclear devices. Also, we know that Iraqi dictator Saddam
Hussein has revitalized his nuclear weapons program. Keeping this in mind,
may I call your attention to an article in the published in the Sunday
Telegraph of London last Sunday. It suggests that an impact event in
Northern Iraq, wrecked the ME civilization some 4,0000 years ago in the area
of Mesopotamia. Dr. Marsden, if such an impact event were to occur in the
same area of the world today and without prior notice, could it trigger a
regional or global nuclear exchange?

BRIAN MARSDEN: Yes, an unforeseen impact like the one mentioned in The
Sunday Telegraph article could certainly trigger a regional if not global
nuclear exchange, and this new concern goes straight to the heart of a
change that is taking place in the NEO (NEAR-EARTH-OBJECT) community. 

Prior to 911, the cause-and-effect relationship between an impact event and
a global nuclear exchange was nothing more than a theoretical debate.
However, since 911 it is no longer theoretical.  It is now a very real
threat for the very reasons that President Bush pointed out during his press
conference with President Chirac.

MARSHALL MASTERS: If this is a new threat since the attack on America, what
kind of impact event scenario could trigger as you say, "a regional if not
global nuclear exchange."

BRIAN MARSDEN: Before delving into any one scenario, we must first ask the
question: could they see it coming?  if we suppose the Iraq feature
mentioned in the Sunday telegraph was an impact event, the impactor was
perhaps a 150-meter object.  That would be very tough for our best neo
search programs.  As for Iraq, I do not ever recall seeing an neo sighting
coming out of that country.

Granted, there are probably people in Iraq who have read books and are
knowledgeable about meteor impacts, but the question of their access to the
leadership of Iraq is debatable. Also, we simply do not know if Saddam
Hussein will seek out their advice. Therefore, Iraq really has little or no
practical ability to differentiate between an incoming NEO impactor and a
nuclear-tipped ballistic missile.

This then brings us to two frightening possibilities for a scenario. Saddam
could initiate a retaliatory nuclear or biochemical launch against Israel
and NATO member states because of a sighting error or, he uses the event as
a pretext to justify a first launch.   Either way, a great many people will
die awful deaths from both the impact event as well as the ensuing war.

MARSHALL MASTERS: When you say that people will die from the impact event as
well as a nuclear exchange, the issue of yield becomes relevant given that
the same measure of force is used to determine the destructive force of both
meteorites and nuclear warheads.  For the sake of argument, how large would
a meteorite need to duplicate the severe regional havoc as the one that
struck Mesopotamia (Northern Iraq) 4,000 years ago?

BRIAN MARSDEN: as I say, it looks as though the meteorite might have been
150 meters across--the size of one of the pyramids in Egypt, say.  An impact
like that corresponds to about 100 megatons of TNT, a little larger than the
largest nuclear detonation to date.  The 150 meters is a guess based on the
size of the crater.  Of course, the impactor could have been somewhat larger
before it came into the earth's atmosphere.

MARSHALL MASTERS: Why do you say it is tough to detect 150-meter objects
with our search programs?

BRIAN MARSDEN: NASA has set a goal to find 90% of the kilometer-sized NEO's
by 2008.  It did this because it was interested in finding objects that, if
they impacted the earth, would directly affect everyone on the planet.  It
is only just becoming interested in objects half a kilometer across or less,
but our current equipment is not optimized to find these smaller objects.
Furthermore, the smaller the size the more numerous the objects, which makes
it harder to catalog a significant fraction of them.

MARSHALL MASTERS: How is NASA in fact doing in terms of its goal?

BRIAN MARSDEN: NASA'S goal with regard to the kilometer-sized NEO's is a
little over-optimistic.  Even though we have found perhaps 50% of the
kilometer-sized NEO's (or, more correctly, near-earth asteroids), it gets
progressively more difficult to find the remainder. After all, we were
already 30% complete five years ago, and I doubt that we can be more than
70% complete by 2008.  

Furthermore, in setting the 90% goal, NASA was really thinking only of
actual detection, and it made little or no provision for the task of
determining the orbits of the objects found with sufficient accuracy to say
for sure that some of them cannot hit us during the next century or so.
Nevertheless, since impacts by kilometer-sized objects statistically occur
at intervals of 100,000 years or more, the odds are better than a thousand
to one that we shan't be hit by one, known or unknown, during the next

While being good odds, they are clearly not acceptable, given the immensity
of the disaster if we just happen to be unlucky.  But given that we shall
surely be continuing to search and refine orbit computations for
kilometer-sized objects long after 2008, the chances will increase, as time
goes by, that we shall indeed be able to recognize the next kilometer-sized
impactor and the date it will hit at least decades ahead, and that will
presumably be enough to send out missions to deflect it.

MARSHALL MASTERS: So you're saying the situation is acceptable with regard
to kilometer-sized objects?

BRIAN MARSDEN: Actually, I think it basically is. There is the problem of
the long-period comets, which are simply too far away and faint to detect
more than a year or two before they could hit us. I think these represent
less than 2% of the problem, but if the hope is actually to find the comets
before they hit, we have to continue to search indefinitely.  The real
difficulty is whether with even two years' notice (and it might be a lot
less), we could actually take evasive action.

MARSHALL MASTERS: And what about 150-meter asteroids like the one that seems
to have hit Iraq 4,000 years ago?

BRIAN MARSDEN: Here the situation is very different. We currently know at
most 2% of the population. True, we knew perhaps only 0.5% of them five
years ago, but we've obviously got a very long way to go before we'd be
likely to know the one that is next going to hit us.  Furthermore, that next
hit is likely to be quite soon. Statistically, a 150-meter object hits the
earth every few thousand years, and if that one in Iraq was the last one,
the next is just about due any day now.

MARSHALL MASTERS: Given that you feel we do not face an imminent danger from
the Kilometer-wide NEO Earth crossers that has NASA's full attention, you've
sure got me worried now about the 150-meter objects. If it is a fact that we
are now in the statistical crosshairs of an impact event like the one that
devastated Mesopotamia 4,000 years ago, I've got to ask:  Are we vulnerable
to an unforeseen impact event of this magnitude today because we simply lack
the technology to track the150-meter NEO's?

BRIAN MARSDEN: No, we have the technology we need to find and catalog these
objects available today.  The reason it is sitting on the shelf is that we
simply lack the political will to put it to work, because politicians find
the costs to be unattractive.

Keep in mind that the funding set aside for attending to dangers is
calculated on a cost-per-death basis. At some point, it simply becomes
prudent from an accounting standpoint to let people die even though their
deaths can be prevented. 

I personally find this cost method analysis to be morally repugnant. But it
is, you could say, the Golden Rule. He who has the gold makes the rules. In
this case those who make the rules have set an arbitrary limit on what they
are willing to spend and all we can do is to make what little they give us
go as far as possible.

Perhaps the new world we live in since 911 will change all that. One can at
least be hopeful and assume so. In any case, the new scenario conceivably
affects everyone on the planet indirectly.

MARSHALL MASTERS: Assuming that the government's thinking has changed, and
that our leadership is now viewing smaller impacts as a matter of national
security and were suddenly willing to fund a search program for 150-meter
objects, what technology would you need to catalog these objects; what would
it cost; and how soon could you have it up and running?

BRIAN MARSDEN: If national security were the primary justification for this
level of effort, we would need to use build and deploy a suite of advanced
special purpose 4- OR 5-meter telescopes in the Northern and Southern
hemispheres, along with computer analysis support and adequate 24/7

Off-hand the cost to build and deploy this system, not including operational
costs, would be approximately 10 million dollars per telescope and it could
take several years to make the full system operational. However, this would,
after a few decades, give us a better than 50% chance of finding potential
150-meter impactors, as opposed to the at best 2% chance we have today. 

Operating costs would likely be in excess of 10 million dollars per year,
and there is a 1% chance the next 150-meter impactor will come, unannounced,
during this time.  Granted, a success rate of more than 90% would therefore
be nice, but that would require extensive searches from space and the
enormous additional cost that would entail.  After all, 50% is a lot better
than we should have if we don't move beyond our current chicken-feed

MARSHALL MASTERS: Any substantial gain in our ability to detect these
150-meter objects is better than what we've presently got, but given the
current fragile and explosive tensions in the Middle East, we simply haven't
got years to deploy such a system, which is not to say it shouldn't be done.
However, for the sake of decreasing what is obviously a serious threat to
our national security, what can we do today?

BRIAN MARSDEN: There a great deal we can do today, provided we have the
political resolve. For example, there are more than enough telescopes of
sufficient size currently in operation that could be quickly re-purposed to
the task cataloging 150-meter NEO Earth crossers, that is, provided the
owners of those telescopes could be convinced to allow the conversion. Aha,
and there would be the rub.  Somebody would have to scratch their backs to
get them. However, this would get us up and going in relatively short order.
Again, it is only a matter of will. We have the technology and as my friends
at NASA would say, "we're good to go."

MARSHALL MASTERS: It is reassuring to know that we have an immediate and
workable option, but the political process in Washington has more twists and
turns than a donkey trail, and all too often all you're left with is what
the donkey leaves behind. Given this, if both of your short-term or
long-term options are viewed as being politically untenable, is there a
politically expedient compromise path we could follow?

BRIAN MARSDEN: we're already stretched to the extreme by obtuse political
compromises and from a general deficiency of funding from NASA and other
international organizations and nations. The problem is that computers --
and even the 1-meter telescopes and imaging devices that are currently being
used -- are cheap when compared with people. Everyone seems to think that
computer technology is all we need, but we cannot do the whole thing with
computers alone. 

Regardless of the equipment funding, it takes real people with real talent
and a real commitment to make this work properly. However, this requires an
ongoing commitment, and this I fear would frighten those in Washington more
than anything else.

MARSHALL MASTERS: One of the most tragic lessons we learned as a result of
9-11, is that when we allow ourselves to become overly dependent on
computers as a people replacement, we're inviting unforeseen catastrophe.
However, many would still argue that it is easier to measure productivity
gains as result of computerization, as opposed to the efficient recruitment
and management of qualified people. With this in mind, how could you
possibly hope to justify the additional manpower requirements inherent a
project of this scale?

BRIAN MARSDEN: That would be very simple. Because the NEO search programs
have always had to beg for money the staff of the Minor Planet Center work
unpaid hours every week. A short week for us is 80 hours, even though we are
salaried at 40 hours. 

But those of us who work on that scale are the lucky ones, you might say, as
others in the search business willingly work full time + overtime weeks but
are paid for only 20 hours. Why do they do it?  Because they believe so much
in what they are doing! I'd certainly love to see a defense contractor like
Boeing or Lockheed get that much productivity out their employees, even at
twice the price.

MARSHALL MASTERS: To be honest, Dr. Marsden, I was a contractor at Lockheed
myself on a satellite project, and from my personal experience I would
definitely say that you have an airtight argument there. But then, I'm not
the one making the decision.  But if I were, the first question I'd ask you
is: "Given your present situation, what are your chances of finding a
150-meter impactor before it starts a nuclear war in the Middle East?"  How
would you answer that question?

BRIAN MARSDEN: Given the present level of financial support for our present
efforts, the chances are somewhere between none and dumb luck. Simply put,
we must now consider ourselves to be wholly vulnerable to this risk, and all
of us in the NEO-detection field find this deeply troubling, since the world
changed for the worse on September 11.

It is About Our Lives and Their Legacies

After concluding my interview with Dr. Marsden, I made a cup of hot coffee
and reviewed our question-and-answer session several times. The part that
really bothered me the most is that our leaders use formulas to decide who
will die and who will live.  Perhaps there was a time when that was a
politically expedient way to manage the NEO threat, but wasn't it was also
that kind of thinking that allowed us to blindside ourselves to the events
leading up to September 11, 2001?

Is it possible that our leaders in Washington will give this national
security threat the attention it deserves?  Most likely not, but they can
depend on one absolute - the Internet will not give them a pass should they
fail us again by letting an unforeseen impact event trigger a global nuclear

Warnings like those mentioned in this article will be tucked away in the
niches and corners of the Internet where future historians will eventually
find them. In that future time, the most urgent goal of generations will be
defined with a simple mantra, "never again." With this mantra in mind, they
apply these candid warnings with firm brushstrokes across the legacies they
will paint for our leaders. 

No matter how great your achievements in this lifetime can be; leaders
beware - do not ignore this potential brushstroke of fate if you truly value
your own legacy. 

About Dr. Brian G. Marsden
Associate director and astronomer at the Smithsonian Astrophysical
Observatory in Cambridge, Massachusetts.

Born in Cambridge, England, Dr. Marsden lived through the air attacks on
England during WW II as a child and remembers the horrors of what happens
when death falls from the sky. Filled with a great purpose by those early
memories, he is committed advocate of public education about the
ever-present threat of impact events, which he does in addition, to his many
NEO detection responsibilities.  He is truly a hero by today's definition of
the term. 

SPECIALTIES: Celestial mechanics and astrometry, with particular application
to the study of comets and asteroids.
EDUCATION: Undergraduate education at Oxford University; Ph.D. degree from
Yale University; dissertation on the orbits of the Galilean satellites of Jupiter.
NOTABLE DISCOVERIES: Successful track record of predicting the return of
several lost comets and asteroids.  His most famous prediction was the 1992
return of Comet Swift-Tuttle, which has the longest period of any comet ever
successfully predicted.
PUBLICATIONS: "Catalogue of Cometary Orbits" -- Thirteen editions published
since 1972.  
(1978 - Present). Responsibilities include the issuance of electronic
information several times each day plus batches of printed circulars monthly
with positional observations, orbital elements and related information about
comets and asteroids.

Director, IAU Central Bureau for Astronomical Telegrams (1968 - 2000).
Responsibilities included the timely dissemination of information about
transient astronomical objects and events. 


>From, 6 June 2002

By Leonard David
Senior Space Writer

DENVER, COLORADO -- Military strategists and space scientists that wonder
and worry about a run-in between Earth and a comet or asteroid have
additional worries in these trying times. With world tensions being the way
they are, even a small incoming space rock, detonating over any number of
political hot-spots, could trigger a country's nuclear response convinced it
was attacked by an enemy.

Getting to know better the celestial neighborhood, chock full of passer-by
asteroids and comets is more than a good idea. Not only can these objects
become troublesome visitors, they are also resource-rich and scientifically
bountiful worlds....

Being struck by a giant asteroid or comet isn't the main concern for Air
Force Brigadier General Simon Worden, deputy director of operations for the
United States Space Command at Peterson Air Force Base, Colorado. He sweats
the small stuff.

Worden painted a picture of the next steps needed in planetary defense. His
views are not from U.S. Department of Defense policy but are his own
personal perspectives, drawing upon a professional background of astronomy.

For example, Worden said, several tens of thousands of years ago an asteroid
just 165-feet (50 meters) in diameter punched a giant hole in the ground
near Winslow, Arizona. Then there was the Tunguska event. In June 1908, a
massive fireball breached the sky, then exploded high above the Tunguska
River valley in Siberia. Thought to be in the range of 165-feet (50 meters)
to 330 feet (100 meters) in size, that object created a devastating blast
equal to a 5 to 10  megaton nuclear explosion. A similar event is thought to
have taken place in the late 1940s in Kazakhstan.

"There's probably several hundred thousand of these 100-meter or so
objects...the kind of ones that we worry about," Worden said. However, these
are not the big cosmic bruisers linked with killing off dinosaurs or
creating global catastrophes.

On the other hand, if you happen to be within a few tens of miles from the
explosion produced by one of these smaller near-Earth objects, "you might
think it's a pretty serious catastrophe," Worden said.

"The serious planetary defense efforts that we might mount in the next few
decades will be directed at much smaller things," Worden said. Some 80
percent of the smaller objects cross the Earth's orbit, "some of which are
potentially threatening, or could be in the centuries ahead," he said.

Nuclear trigger

One set of high-tech military satellites is on special round-the-clock
vigil. They perform global lookout duty for missile launches. However, they
also spot meteor fireballs blazing through Earth's atmosphere. Roughly 30
fireballs detonate each year in the upper atmosphere, creating equivalent to
a one-kiloton bomb burst, or larger, Worden said.

"These things hit every year and look like nuclear weapons. And a couple
times a century they actually hit and cause a lot of damage," Worden said.

"We now have 8 or 10 countries around the world with nuclear weapons...and
not all of them have very good early warning systems. If one of these things
hits, say anywhere in India or Pakistan today, we would have a very bad
situation. It would be awfully hard to explain to them that it wasn't the
other guy," Worden pointed out.

Similarly, a fireball-caused blast over Tel Aviv or Islamabad "could be
easily confused as a nuclear detonation and it may trigger a war," Worden

Meanwhile, now moving through the U.S. Defense Department circles, Worden
added, is a study delving into issues of possibly setting up an asteroid
warning system. That system could find a home within the Cheyenne Mountain
Complex outside Colorado Springs, Colorado. The complex is the nerve center
for the North American Aerospace Defense Command (NORAD) and United States
Space Command missions.




>From Michael Paine <>

Dear Benny

In his book 'Comet and asteroid impact hazards of a populated Earth', John
Lewis describes more than 150 reports of damage, injury, death and near
misses that are best attributed to cosmic impacts (mostly very small or
fragmented objects). He suggests that the assertion "nobody has ever been
killed by a meteorite" is indefensible and that a more accurate summary of
the evidence would be "nobody has ever been killed by a meteorite in the
presence of a physician and a meteoriticist". Taking Hermann Burchard's
point (CCNet 5Jul02), perhaps that should read
"nobody has ever been killed by a meteorite in the presence of a physician
and a meteoriticist WHO SURVIVED THE IMPACT"

Michael Paine


>From Peter Haines <>

Dear Benny,

I have just read with interest the 'in press' paper by Fawcett and Boslough
that has been discussed in recent days. On page 31 the authors speculate
that late Neoproterozoic glaciations may have been caused by impact-induced
rings, and point to the age similarity between the Acraman impact and the
Marinoan glaciation. While I find the overall concept of a ring-glaciation
connection rather interesting and provocative, there is no possibility of a
genetic link between Acraman and the Marinoan glaciation. The age for
Acraman (now generally given as ~580 Ma) is not derived from the crater
itself, but is a stratigraphic age obtained from an ejecta layer within
Neoproterozoic shales of the nearby Adelaide Geosyncline (Gostin et al.
1986). The Adelaide Geosyncline is also the type area of the Marinoan
glaciation and the glacial deposits and the ejecta are found in the same
stratigraphic sections where the later always lies above the former. In the
classic Bunyeroo George section the ejecta layer lies nearly 1000 m above
the cap dolomite marking the end of the glaciation. However, it may be worth
noting that there has been speculation that one of the glaciations preserved
in northern Australia is possibly younger than the type Marinoan (Grey &
Corkeron 1998). Incidentally, the generally accepted size of Acraman is now
90-95 km (rather than the 150 km quoted), with some authors suggesting a
significantly smaller diameter.

Gostin V.A., Haines P.W., Jenkins R.J.F., Compston W. & Williams I.S. 1986.
Impact ejecta horizon within late Precambrian shales, Adelaide Geosyncline,
South Australia. Science 233, 198-200.
Grey, K. & Corkeron, M., 1998. Late Neoproterozoic stromatolites in
glacigenic successions of the Kimberley region - Western Australia: evidence
for a second Marinoan glaciation. Precambrian Research 92, 65-87.

Best regards, Peter Haines
University of Tasmania

*  Dr Peter Haines
*  School of Earth Sciences, University of Tasmania
*  GPO Box 252-79 Hobart, Tasmania 7001, AUSTRALIA  
*  email:
*  phone: +61 3 6226 7157      fax: +61 3 6223 2547 

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