CCNet SPECIAL, 16 October 2000


By Jurgen Kronig <>

- A shorter version of this interview, made a few weeks before the Task
Force Report was released, was published in the German weekly DIE ZEIT (15 September


JK: Let me begin with a very simple question, Sir Crispin: why did the
British Government decide  to set up such a Task Force suddenly, out of the

CT: Well, it's a good question. Some people thought that the British
Government had access to some threat that was not known to the general
public and this was a sort of panic measure. In fact it wasn't. It was the
product of the substantial research that has been done over the last few
years, greater understanding of the nature of the problem and - perhaps most
important of all - debate in the House of Commons in March 1999, when the
matter was very thoroughly gone into.  People began to laugh at the idea,
but they ended by being quite serious about it. So I think the Minister of
Science, Lord Sainsbury, decided that it would be a wise thing to do to set
up a Task Force to go into details and to look at things very carefully.

JK: But why Britain? To give a good example to other countries or because
they are more aware of the problem?

CT: I suppose in some respects astronomy has always been a particular
British interest and we have made great contributions to astronomy in the
past with a lot of distinguished astronomers. It seemed just useful that we
should look into the issue and make recommendations. It is quite obvious
from our terms of reference that we are looking into how this matter can be
carried forward to the international arena as well. Thus the Task Force was
- I quote from its terms of reference - it was asked to 'confirm the nature
of hazard and potential levels of risk, to identity the current contribution
to international efforts and advice the Government about what further action
to take, and how the issue should be communicated to the public.' So we are
not going to set up an all-British effort to determine the subject,
determine the threat,  but considering what is the most useful British
contribution to what must be an international effort in which, of course,
the great leader at the moment is the US.

JK: The Task Force was set up at the beginning of this year, the Year 2000.
You have prepared a report. Could you give us the gist of that?

CT: We were given 6 months to investigate the problem and come up with our
recommendations, which means that it is not going to be an immensely
detailed piece of work. It is really a six  months look at a very
complicated problem in which, as one of the 3 members of the task force, I
find that the problem is not lack of information, but it is how to make
sense of the enormous quantity of information that is now available. And we
have tried to do that

JK: So first you locked at the potential risk. Can it be quantified?

CT: I suppose you could put it like this: our first task really was to
identify what is the problem and look at some of the history of near earth
objects impacts with the earth. There had been such impacts throughout
history, and nowadays we understand much better than before exactly what has
been going on. I mean the more we got into it, the more interesting, of
course, we found it. Perhaps, if I can mention a couple of examples. When I
was in the US recently, I was in the Pentagon, and the Americans referred to
a little impact on the 18th of January. Well, that wasn't published in
Europe, although I think it is now generally known, where an object that had
something like 5 m in diameter exploded over the Yukon and showered the
place with bits, it emitted a lot of light, made a bang and more important,
it distracted radio communications. So that was only 5 m in diameter, that
happened this year. Then you find that over the last 10 years there have
been a succession of events which haven't on the whole been noticed by the
general public. The general public did notice of course the impact of the
comet Shoemaker-Levy on Jupiter in 1994 when it created a fireball as big as
the earth.  And that was another factor, I think, which caused great public
interest. It was a warning sign, it showed people what could happen if - and
it attracted a lot of interest. And since then more evidence comes out every
day about the impact of 1000s of tons of dust that are entering the earth's
atmosphere which is not, I think, common knowledge. And then we looked back
at some of the bigger impacts just during this century, and you will find
that there was quite a large object hit the Brazilian rain forest in 1930,
another hit Guyana in 1935, and, as every knows, there was a major impact in
1908 when an object about 50 m in diameter exploded over Tunguska in
Siberia. Now a little calculation which shows how important that is, is that
had that object struck an inhabited area such as London or Berlin or
anywhere else, it would have done tremendous damage. Indeed, had that object
hit London in 1908 and not the Siberian forest, it would have eliminated all
of London within the outer ring road of the M25.

JK: Isn't it true that the scientific community has, for quite a long time,
been and still is resitsing the idea that the history of mankind, not only
the history of this planet, has been shaped much more heavily by impacts, by
bombardment from space, because this runs against the idea of slow
progressive evolutionary development.  Is there not still quite a lot of
resistance against this more cataclysmic view?

CT: It is certainly true that a great many people until recently believed
that the earth was a closed system, that we didn't have to worry about
anything outside the earth. This idea goes back to those people who thought
that the earth was the centre of the solar system, and indeed that the solar
system was the centre of the Universe, and people wanted to believe that
change was by slow, gradual means. They didn't really want to bring in the
idea of life affecting it, which brings in another very interesting set of
arguments. They liked the idea that the earth is physically close a part, a
closed system that doesn't have impacts, which is why there was so much
resistance when the Alvarez, father and son, produced the hypothesis that
the reason for the demise of the dinosaurs, 65 million year ago, was the
impact of an asteroid or comet (nobody knows which), which had this
cataclysmic effect. Then they produced the evidence which showed in the end
that this had indeed happened, that there was a crater of 180 km in diameter
in Mexico, in Yukatan. And gradually, people, after fierce resistance to the
idea, have come much more inclined to accept the fact that the earth's
history is constantly affected by cataclysmic events. You must remember that
in the arguments that took place over Darwin - Darwin believed that
evolution was by gradual means, although he always allowed for some abrupt
changes - and when people suggested that evolution of life might also be
subject to abrupt changes of the kind that could be produced by impacts from
outside, I gather there was a lot of resistance. And people like Stephen J
Gould, with the idea of what he called 'punctuated equilibrium' - the
equilibrium being the steady evolution, the punctuation being some event
from outside or an event which disrupts the normal course of development,
all this also produced resistance.

JK: Did you encounter this remnants of resistance in your talks, in your
negotiations and discussions with scientists and politicians?

CT: No. I find that the most interesting reflection on the whole from
politicians an from others is not that.  It is ... well, alright, you are
right, there have been many of these cataclystic impacts in the past but
what on earth can we do about it?  Wouldn't it be better to worry about the
price of bread or the distribution of wealth in the world, or the current
problems that vex mankind, rather than worry about something that is very
remote and if it ever happens would be quite uncontrollable and quite
unmanageable in any way.

JK: What is your answer?

My answer is: some of the really big stuff might indeed be that, be
uncontrollable, but that, for the first time ever in the history of life,
one particular animal species has got it within its power, at least
theoretically in its power, to deflect catastrophes of this kind. And it
would be gross irresponsibility if we would not look into it. And above all,
that we should need to know much more about what the threat really was and
consider what could be done. For example, you could find that it is a
problem, in a sense, of civil defence. Supposing there is an object going to
hit Britain or Germany, there would be a major question of what should the
local defence authorities do. Should you try to get people away from the
coast where you might have the risk of huge waves, washing people away, or
what should you do? And so it would be a problem of civil defence.  There is
also the problem of saying: well, we can see the problem of 10 years from
now a comet or a fragment of a comet is likely to hit the earth. Can we put
our heeds together and do something which might deflect it, in which case it
would be very irresponsible of us not to try and do so. This was mode a
theme, of course, in the film Deep Impact', which greatly affected the
public mind about it, and Armageddon as well.

JK: Before we come to the question of what can be done, what are the
technologies available if there are any...- another question regarding the
reaction of the scientific community and the wider public: You could argue
that we had very severe cataclysms, most probably caused or definitely
caused by the impact with comets or asteroids, but the argument goes: now,
for the last few millions years, it has been quiet, this was in a different
period in the history of our planet, and it is so unlikely. Or is this
opinion wrong, have we been more or less in a state of amnesia and didn't we
really take into account that catastrophes caused by the collision with
heavenly bodies might have happened in historical times. For instance some
astronomers suggest that the Dark Ages were triggered by cosmic bombardment.

CT: Right.  Well, in the early history of the universe there were certainly
many more impacts than there are today, that seems to be fairly clear.  You
could see the results of impacts on the moon. The latest observations from
the asteroids that have had close pictures taken of them show that they are
absolutely pitted and covered with impacts. So we know that in the early
history of the universe there were a lot of them. Since then, there has
probably been a diminution in the number of impacts, but we know nothing to
suggest that the impact rate has diminished in the last million years,
Indeed, now that we are finding out a lot more about it we can discover what
the impact rates are likely to be. In the case of the earth, the forces of
wind and weather and erosion tend to eliminate, tend to cover up the effects
of impacts but there is one crater, for example in Germany, which is very
important; one in Chesapeake Bay where the city of Washington is now built,
there was a crater. There are very large craters in Africa and Australia. So
wherever you look, you will probably find more craters, but nature has
covered them up for us. In the last few years, people have been trying to
look for periodicities. It is certainly true that every year there are
certain astronomical events, like the arrival of certain meteors, the
Leonids and other examples, which are periodical.  But the efforts a number
of people have made to show that we come under heavy risks every 28, 29
million years have not actually so far proved their case.  There are periods
where you get more of those sort of thing happening but there are also
periods where things don't happen very much.  There is nothing to suggest a
regular rhythm that we have been able yet to determine. The current
situation is that there is a constant movement, a constant bombardment of
the earth from outer space, mostly very small things that most people don't
notice, some microscopic dust, but this has continued and, little doubt, it
will continue.

JK: But there are a lot of near earth asteroids or near earth objects in the
inner solar system which might be potential collision candidates. The first
task is to find out how many are there, where are they end and are their
orbits a potential danger for earth.

CT: Well, as far as we know, and I must underline that I am not an
astronomer, we know of nothing at the moment which is on a collision course
with the earth. But our ignorance is so great that we can't really be
certain about it. The Americans have done a lot of work on objects of more
then 1km in size, in diameter, so we don't think that any objects of 1 km or
above are about to hit the earth. But, after all, some of the other ones can
cause very bad impacts. They might not destroy civilisations but they can
certainly make a very nasty hole in the earth. And if you look at the crater
in Arizona which was produced about 49,000 years ago, that had a diameter of
about 60 m. A lot depends on what the asteroid is made of: is it made of
rubble, is it rock, is it hollow, which is the case in perhaps one or two of
them, there are hallow elements, or is it metal? What is likely to happen in
each case is very different because of the asteroid.  So, by and large, we
don't know of any regular periodicities. Calculations have been done to show
that objects of 50, 60 m in diameter are likely in a time span of a hundred
years, but the big stuff, that is to say more than one km, is more likely in
100 000 years or in millions of years.  We don't know.

JK: First we have to know that they are there and how many of these 1 km in
diameter or more are in the solar system.

CT: We know roughly, but we don't know with any great precision. And, of
course, observation are nearly all taking place in the northern hemisphere
rather than the southern hemisphere which limits the field.

JK: Will this gap be closed?

CT: We would like to do so. One of the things we have been thinking about is
the way you get better observations from the southern hemisphere but then
some of the new telescopes being set up in Chile will be able to resolve
that problem.

JK: What about possible defence mechanisms?  To be able to deflect, to

CT: Well, that is a huge area of technology in which certainly I cannot
claim to be an expert.  There are those who would say that you have to let
off a nuclear device in order to deflect it, so that you wouldn't try to
destroy it. Because destroying it could mean that the object would remain in
its orbit and it would merely mean that instead of one impact you have 50 -
as happened in the case of Shoemaker-Levy 9 on Jupiter. The other
possibility is that you should try and deflect it, and there have been a
number of suggestions. There have been those who suggest that you should
make a big nuclear explosion in space, and thereby creating a blast which
pushes it out of orbit, depending on the size and the character of the
object.  If you didn't get it right, you might break it into fragments which
might make things worse rather than better. And there are those who believe
that you create something like a limpet, that you attach to the object and
power it by solar energy, and provided that it was far enough away, you
could gradually nudge it nut of orbit into another orbit,  that would pass
by the earth. And there are people who are very suspicious, who say ha, ha,
but perhaps you would nudge an object which was coming towards Berlin and
nugde it into a direction which lead it perhaps towards Moscow or Bejing. So
it is very difficult. I think that is real fantasy. So we looked into all
these different things, and obviously a task force in 6 months can't come up
with technical answers. And I must underline that nearly all the serious
practical work on this subject has been done in the US.

JK: You went to the US, what did they tell you in the Pentagon, for

CT: One, I was very impressed by the degree of information that they put
together. I was also impressed by their frankness in admitting that this
knowledge was incomplete. Our conversations were, of course, strictly
private. But the question of an object arriving from outer space was quite
close to the idea of an object arriving from a hostile country, and that way
you are getting into what might be described as the star wars area quite
quickly. And the Americans have done a lot of work look into these
questions. I had the privilege of also going to the observatory at Cape Peak
and actually looking at some asteroids through their telescopes which was
very interesting because you can actually see them moving around. (They are
asteroids going peaceably about their business in the asteroid belt which
lies between Mars and Jupiter). So, the Americans have done an impressive
amount of work but, so far, they have not created a kind of co-ordinating
mechanism. Indeed, one of the interesting things is that no country in the
world has yet tried to co-ordinate its research and its civil defence and
possible deflection abilities into anything like a single organisation. So
we have been thinking about what we ought to do to look at the international
level, the European level, because the Europeans might have a lot to
contribute, the national level and what kind of institutions might be right
for each case.

JK: You mentioned all these different suggestions to deflect or destroy or
defend against.
Wouldn't star ware be a useful tool? I mean star wars, originally planned as
a safety system against hostile missiles, could be turned around?

CT: Exactly, I agree with that.

JK: And are there any movements in this direction?

CT: Not that I know of. Maybe there is something and I haven't heard about
it, but I haven't heard that it is going to be used, although it is
obviously very relevant. What I think is interesting is that the fact of our
task force being set up has caused a lot of people to think again about it.
I won't say that the task force is going to produce a report that will shake
the world, but the mere existence of a task force to lock into the subject
has certainly had some effects of the European Space Agency. They are
thinking about things more than they would have done otherwise. And I was
told by our American friends that the fact that we have sat up this task
force and the kind of people appointed to it had the effect that their
community also began to think about it again.  So at least we had a
catalystic effect.

JK: And did you get a response from all the other governments, did the
European Union for instance react or did they...

CT: Not yet, as far as I know. Well, with the European Space Agency, there
has been a lot of interest, and we talked to people there and we talked to
people at the European Space Observatory, the one that is going ahead in
Chile. And we have talked, of course, to the International Astronomical
Union which is the international body which looks at these things. So maybe
the appointment of a task force and the kind of work we are doing, however
general, does have a sort of catalystic effect in making people feel they
need to think about it and maybe also encourage them to think about how
research may be better co-ordinated in the future.

JK: Do you cover in your task force discussions in the delicate field Of who
should be informed about an approaching near earth object which might hit
the earth, or definitely hit the earth?

CT: Well in our terms of reference there is a point about communication with
the public which, of course, raises a very difficult question. First, I
think it is much better always to be open on these questions, not least
because if you aren't open, you are soon found out. Supposing some
astronomers found something heading for the earth - do you think that they
would be willing - supposing that they have clearer view - do you think that
they would be willing to keep the thing quiet?  The answer is that human
nature is such that those people who made a major discovery would not wish
to sit on it, they would let it be known, somebody would leak it sooner or
later. And so the possibilities of withholding information of this kind
seems to me to be a complete fantasy. So the question is: can you create a
public co-ordinating body which will give measured advice to which
journalists will turn when they want to know something. And that, I think,
is the answer: you have got to be open, you can't - even if you wanted to -
keep things quiet.  So what you have to do is to make sure you have a
measured and sensible response, you have to steer a course between creating
alarm or creating complacency. This problem is real although it is unlikely
to affect any individual very seriously in the world today. It is a very
real problem, and somehow you have got to strike that balance.

JK: In a way it is an attempt, for the first time, to look far beyond the
limits of one or two generations. It might be a problem in 100 or 200 or
1000 years.

CT: It could be a problem in 100 or 1000 or 200 years, whatever you like. It
might also be a Problem tomorrow morning. And that gives it rather a
different aspect. The biggest present analogy is with climate change. In the
case of climate change you have got international institutions set up to try
to measure the effects and to measure the impacts. And the evidence can
accumulate, climate change is already taking place. You can try and make
judgements about it and consider what should he don about it, because this
knowledge is accumulative, it is there all the time. In this event you are
faced with an entirely new situation in which something could happen very
quickly and very disastrously, or it might need 20 years, 100 years, or a
thousand years. So you have got a very difficult balance to make. What is
interesting there is that the amount of knowledge that we need to acquire is
so great that we may as well get on with it straight away, even if the
knowledge of what we would do about it, is bound to leg behind.

JK: You just used the comparison with climate change and the international
response. Would you not say that the international response with climate
change is disappointingly falling behind in what it should be?  If we draw a
parallel from here to there, nothing really might be done in terms of
defence systems against Collisions.

CT: Well, I am a realist, and in the case of climate change - a subject
which I have been involved with for a very long time, indeed I wrote a book
about it in the 1970's, you have an accumulating public knowledge of the
subject, a series of world climate, two world climate conferences, people
understanding much better what is going on, a series of international
commissions set up, and now you have the framework agreement on climate
change of 1992, you have frequent meetings of the parties, all that. You cab
say they haven't. done very much about it so far, that is true, they have
not done a great deal. But I think the momentum is now there, and when they
meet later this year to consider which steps should be taken, you will find
that there is an accumulating public concern and that people can begin to
see. And besides, if climate change starts to have catastrophic effects,
then people will begin to say, what are you going to do about it? So nature
is on your side, demonstrating that climate change is taking place.
Just look at the last 2 or 3 years, one of the predictions has been more
extreme events. There have been extreme events, and what I was hearing from
the Chinese about the extraordinary dust storms that have been covering
Northern China, as well as the flooding in Mozambique as well as the
flooding in Venezuela - all these things are happening. And so, public
understanding of the hazards of climate change is going to increase as the
drama unfolds. This is not the case with near earth objects, something
disastrous may happen in a year, something disastrous may not happen for a
thousand years.

JK: The German-Jewish philosopher Hans Jonas, in his address to the
Frankfurter Friedenspreis, raised the question of 'how much catastrophe
mankind needs to endure in order to change'.  He was referring, of course,
to climate change and so on. But if he is right, and the answer is: a lot,
people don't act without the experience of catastrophe, then, of course, it
makes life even more difficult for advocates of a defence system against
cosmic collisions.

CT: It does. But you just have to face this. I think catastrophes on the
whole have rather a fruitful effect in human history, because people will
not do anything until they see the need to do something. You need, in a way,
a combination of 3 things: you need people to give leadership, you must
respond to pressure from below when citizens put the heat on politicians to
get on with something. And, sometimes, politicians are very reluctant to do
so because they are driven by vested interest. But you find that people just
feel strongly, and I think, for example, the problems of transport policy in
Europe and especially in Britain are now forcing politician to think
differently. And then you have catastrophes, and all one can hope is that
the catastrophe isn't too big and awful, and that, preferably, it shouldn't
affect you.

JK: Let me finally ask you: When You discussed this new task force with your
Prime Minister, did he strike you as a Politician who is responsive to
issues like that?

CT: I think the Prime Minister is very conscious of a whole variety of
threats to stability. This is a subject which is clearly somewhat exotic
because it hasn't been talked about at that level, it has been talk about by
astronomers. It is rather in the position of climate change, as we have
discussed, but I wrote my little book in 1975 -  it is something which few
people think about. Well, I think that the issue of near earth objects has
yet to arrive at the political level, it is somewhere far below the
political level at the moment. And one of the purposes of the task force is
to alert people, even people who don't understand astronomy, or are not even
interested in astronomy to grasp what the issues really are.

* Sir Crispin Tickell is a member of the UK Task Force on Near Earth
Objects. For many years, he was one of Britain's top diplomats, serving,
among other placements, as the UK ambassador to the United Nations. He is
the chairman of the Royal Geographical Society and is Chancellor of the
University of Canterbury.

* Jurgen Kronig is the UK correspondent for the German weekly DIE ZEIT and a
freelance author for various publications and TV in Germany, Switzerland and Britain.


CCNet 104/2000 - 16 October 2000

     "Sweden's energy authority said on Friday it was investing in a pilot
     project to take energy for heating from a meteor crater. The crater,
     located outside Stockholm and with a six-mile diameter, could have
     a capacity of 4,000 terawatts which would cover 70 percent of Stockholm's
     heating needs. The energy of the crater is created when a meteor hits the
     earth, making the ground up to 10 times more porous, allowing water to be
     warmed by the earth's heat."
      -- Reuters, 13 October 2000

      "Space-based telescopes are necessary to observe close to the sun due
      to scattered-light problems. As Dr. Tholen points out, ground-based
      searches here are difficult at best. [...] Second, and more important
      is the misconception that space-based observatories are expensive."
          -- S. Pete Worden, Brigadier General, USAF

    Ron Baalke <>

    Ron Baalke <>

    Mark Kidger <>

    Wichita Eagle, 14 October 2000


    BBC Online News, 13 October 2000

    The Independent on Sunday, 15 October 2000

    Piazzi2001 <>

    Brigadier General Simon P Worden, AF/XOC <>

     A.R. Hildebrand et al.

     Alan Harris /DLR, Berlin <>


From Ron Baalke <>

Meteor Crater Probed for Heating Energy
October 13, 2000

STOCKHOLM (Reuters) - Sweden's energy authority said on Friday it was
investing in a pilot project to take energy for heating from a meteor crater.

The crater, located outside Stockholm and with a six-mile diameter, could
have a capacity of 4,000 terawatts which would cover 70 percent of Stockholm's
heating needs.

The energy of the crater is created when a meteor hits the earth, making the
ground up to 10 times more porous, allowing water to be warmed by the
earth's heat.

Full story here:


From Ron Baalke <>

Los Alamos National Laboratory
News Release

CONTACT: James E. Rickman, 505-665-9203 (97-155)


Los Alamos array detects large, bright meteor: Laboratory researcher joins
the search

LOS ALAMOS, N.M., Oct. 10, 1997 - Researchers at Los Alamos National
Laboratory were able to use an array developed to listen for clandestine
nuclear weapons tests to help locate a large meteor that flashed in the sky
Thursday afternoon above Southern New Mexico.

The object -- presumably a large, bright meteor known as a bolide -- was
seen in the skies Thursday at about 12:47 p.m. Witnesses said the object was
at least as bright as the full moon or as bright as the setting sun.

"The meteor made a huge sonic signal," said Doug ReVelle, a meteorologist in
Los Alamos' Atmospheric and Climate Sciences Group. "They heard it like a
freight train in El Paso."

Using data from Los Alamos listening stations originally set up to monitor
nuclear explosions, ReVelle and other researchers in Los Alamos' Atmospheric
and Climate Sciences Group analyzed the infrasonic signature created when
the meteor entered the atmosphere.

When a meteor enters the atmosphere -- or when a large explosion is
detonated -- it creates a sound or pressure wave that is below the range of
human hearing. This infrasonic wave travels through the atmosphere and can
be detected by special microphones that are set up in an array. By looking
at the time of arrival of the sounds at different stations and the frequency
of the infrasonic boom, researchers can pinpoint the location of the source
and the determine the amount of energy that created it.

"The data from our array puts the meteor 441 kilometers due south of Los
Alamos," said ReVelle. "We'll be looking for it in a location we've
identified near El Paso."

ReVelle will join researchers from Canada, the University of New Mexico and
Sandia National Laboratory on a search this weekend for any meteor fragments
that may have reached the ground.

"The object's infrasonic signature was equivalent to the explosive yield of
about 500 tons of TNT," ReVelle said. "That means the object was somewhere
around one half to three-quarters of a meter in diameter."

Thanks to the infrasound array at Los Alamos, researchers at the Laboratory
were able to narrow down the location where it may have landed pretty well.

In addition to searching for remains of the meteor -- which may have
exploded into tiny bits in the sky - the researchers will interview
witnesses about the object: how bright it was; what it sounded like.

The object created a brilliant light as it streaked toward Earth. Witnesses
in Santa Fe, Los Alamos, Albuquerque, El Paso and points in between saw the
object in the sky.

ReVelle and the others will search all weekend for the object and collect
other data as well.

"It could take weeks to find, but it could take a day or less, depending on
how lucky we get," ReVelle said.

Infrasonic waves are very low frequency sounds that exist somewhere in the
realm between hearing and meteorology, ReVelle said. The sounds are well
below the range of human hearing, which ends at about 30 hertz, but actually
can be detected as small changes in atmospheric pressure. If someone had a
barometer that was sensitive enough, that person would be able to see
fluctuations of several microbars when infrasonic waves arrive.

During the 1960s and early 1970s, before the rise of the satellite era, the
United States Air Force operated a network of stations to listen for nuclear
weapons tests. The listening stations were the nation's first line of
detection for nuclear explosions worldwide.

The four arrays of listening stations operated by Los Alamos are the only
infrasonic network left in full-time operation in the world. They can detect
meteors that are as small as a few centimeters in diameter. The stations are
useful because they can help validate other non-proliferation and
verification techniques, and they cost very little to operate and maintain.

The Los Alamos stations, around since 1983, still are enlisted in the
nation's nuclear non-proliferation efforts, but have provided a way for
scientists to detect bolides, larger-than-average space debris that slams
into Earth's atmosphere and creates brilliant fireballs in the sky.

Each year a number of large meteors enter the atmosphere and are detected by
the Los Alamos array. Some meteors are tens of meters in diameter. ReVelle
said each year about 10 meteors that are two meters in diameter - with an
energy equivalent of a one-kiloton blast - enter the atmosphere. Most burn
up or explode in brilliant flashes. Some hit the ground.

For this weekend's search, ReVelle will join Peter Brown of the University
of Western Ontario; Alan Hildebrand from the National Research Council in
Ottawa, Ontario; a researcher from University of New Mexico's Institute of
Meteoritics; and Mark Boslough of Sandia National Laboratory.

Los Alamos National Laboratory is operated by the University of California
for the U.S. Department of Energy.


From Mark Kidger <>


You may be interested in running something on the big Kansas fireball seen
just after sunset last Friday. You can find it on:

Several updates on the story are due later today as the 8 hour time
difference with California meant that they came too late to be included last night or
this morning. There is a suggested identification with a Russian Glonass



From Wichita Eagle, 14 October 2000

Officials say the fireballs were probably a large meteor breaking up or
"space junk."

By Novelda Sommers
The Wichita Eagle

Those weren't alien spacecraft that streaked across the sky Friday night
over Wichita.
The fireballs that left glowing trails of smoke lingering in the heavens
were likely caused by a meteor that broke up as it entered Earth's
atmosphere, said Greg Novacek, director of the Lake Afton Public

Hayden Frank, a meteorologist with the National Weather Service, said he
thought the lights were caused by "space junk" entering the atmosphere.

The lights moved over Sedgwick County just after sunset Friday, putting on a
show for startled residents.

Lt. Bret Giffen of the Wichita Police Department's south substation, said
callers inundated emergency dispatchers about 7:30 p.m., reporting what some
thought was a plane crash and what others described as "a fire in the sky."




Dennis Urquhart
Research Communications
(403) 220-7722


Researchers at The University of Western Ontario (Western) and the
University of Calgary (U of C) -- working with colleagues from Canada,
the United States and the United Kingdom -- have found that meteorites
recovered in northern British Columbia may be one of the most primitive
solar system materials ever examined.

Peter Brown, a professor in Western's Department of Physics and
Astronomy, and Alan Hildebrand, a professor in the Department of Geology
and Geophysics at U of C, are the lead authors of the report featured on
the cover of the Oct. 13, 2000 issue of the international journal Science.

The meteorites, recovered by B.C. resident Jim Brook in late January, and
scientists at Western and the U of C during April and May, were found on
Tagish Lake, B.C. It was the largest meteorite fall in Canadian history.

"We can now say that this may be the 'crown jewel' of meteorite finds,"
says Brown. "This discovery will aid scientists in the reconstruction of
the early solar system."

"The standard composition of the solar system is partly defined by the
most primitive meteorite in existence," says Neil MacRae, earth sciences
professor at Western and a co-author on the Science paper. "If our results
are proven correct, this new discovery will ultimately change that

The Tagish Lake Meteorite is a new type of carbonaceous chondrite -- a
rare, organically rich, charcoal-like class of meteorites. Carbonaceous
chondrite meteorites make up about three per cent of meteorite finds in
the world. The chemical class most closely resembling this meteorite
constitutes less than 0.1 per cent of all meteorites recovered to date,
though the Science paper suggests the Tagish Lake Meteorite to be even
more primitive and therefore may represent a new class.

The first recovered pieces of the Tagish Lake Meteorite have been kept
frozen, which will allow researchers to identify the full range of
compounds in a primitive, carbon-rich meteorite for the first time.
These organic materials may help scientists better understand chemical
processing in the outer part of the solar nebula. The meteorite is also
rich in interstellar grains. Coupled with the limited aqueous alteration
on the parent asteroid of the Tagish Lake Meteorite, this may mean that
new things will be learned about the nuclear furnaces of stars.

"The most significant and exciting things to be discovered in this
meteorite may not yet be known," says Hildebrand. "We, together with
Jim Brook, are supplying material to dozens of researchers located around
the world for their studies. It is a delightful and somewhat rare situation
for scientists when we can't predict what may be learned."

Other members of the research team include Michael Mazur, Tina
Rubak-Mazur, Michael Glatiotis, and J. Andrew Bird at U of C; Michael
Zolensky at NASA Johnson Space Center; Monica Grady at the Natural
History Museum in England; Robert Clayton and Toshiko Mayeda at the
University of Chicago; Edward Tagliaferri at ET Space Systems in
California; Richard Spalding of Sandia National Laboratories in New
Mexico; Margaret Campbell, Robert Carpenter, Heather Gingerich, Erika
Greiner, Phil McCausland and Howard Plotkin at Western; Eric Hoffman
at Activation Laboratories Ltd. in Ancaster, Ontario; David Mittlefehldt
at Lockheed Engineering and Science Co. in Houston; and John Wacker at
the Pacific Northwest National Laboratory, Richland, Washington.


For more information, please contact:

Peter Brown at (519) 661-2111 ext. 86458
Alan Hildebrand at (403) 220-2291 or cell (403) 874-1434

For B-roll footage, a copy of the Science paper or to arrange interviews,
please contact:

Marcia Daniel
Communications and Public Affairs, The University of Western Ontario
(519) 661-2111 ext. 85468
Dennis Urquhart
Research Communications, University of Calgary
(403) 220-7722

For photos, biographies, backgrounders and video footage, please visit the
following websites:


Attention broadcasters: The University of Western Ontario has installed
Bell's VideoROUTE service that allows for live or pre-taped broadcast
interviews with television studios. For more information, please call
(519) 661-2111 ext. 85468 or ext. 85165.


From the BBC Online News, 13 October 2000

By BBC News Online science editor Dr David Whitehouse

Scientists have revealed new data about a meteorite that could be one of the
most primitive Solar System objects yet studied.

The space rock was recovered from the frozen Tagish Lake in Canada. The
meteorite has aroused huge excitement among researchers because its
fragments could help us understand better how the planets were formed.

The rock fell to Earth on 18 January, 2000. The exceptionally long and
bright fireball was seen throughout the Yukon, Northern British Columbia,
parts of Alaska, and the Northwest Territories.

Several dozen pieces of it have been retrieved. Importantly, the pieces were
picked up still frozen, providing researchers with a unique opportunity to
study organic compounds that may even have been the building blocks of life
on Earth.

The Tagish Lake meteorite is a so-called carbonaceous chondrite, a rare type
of ancient meteorite that makes up only 2% of all meteorite finds. Unlike
most rock found in the Solar System, it has not been changed by major
heating sometime in its history and as such allows researchers a chance to
study the very stuff that came together to form the Sun and the planets.

Analysis of the Tagish Lake meteorite, reported in the journal Science by
Peter G Brown at the University of Western Ontario, Canada, and colleagues,
suggests the rock may represent a completely new class of carbonaceous
chondrite, more primitive than any yet found.

Using eyewitness accounts, photographs, videos, and satellite data of the
rock's fiery and dramatic entrance into the Earth's atmosphere, the
researchers have also calculated where the meteorite came from.

Its trajectory indicates that the space rock originated from the middle of
the asteroid belt which lies between the orbits of Mars and Jupiter (about
300 million to 600 million kilometres/186 million to 370 million miles from
the Sun).

Many researchers want to study the unique meteorite

Analysis of the carbon in Tagish Lake indicates that some of it is in the
form of so-called nanodiamonds, tiny particles of interstellar material that
were in the solar nebula, the cloud of gas and dust that came together to
form the Solar System. Tagish Lake may be richer in interstellar grains than
any meteorite studied before.

Jeffrey Grossmann of the US Geological Survey says that Tagish Lake is the
most significant meteorite to come into the hands of scientists since the
well-known Allende meteorite from Mexico and the Murchison meteorite from
Australia, both of which were picked up in 1969.

Alan Hildebrand of the University of Calgary, Canada, says that the best
indication of the significance of the Tagish Lake recovery can be seen in
the receipt of dozens of requests from meteorite researchers around the
world to study the new rock.

Many small fragments have now been recovered

One very interesting aspect of the Tagish Lake study is the compilation of
detailed eyewitness accounts of the fireball.

Many people noticed smells at the time of the rock fall. These were
frequently described as sulphurous, although hot metal and rock were also
mentioned. And these smells were picked up by people many tens of kilometres
from the drop zone.

About one in 10 also reported sound instantaneous to the fireball event. It
might seem impossible that a noise can be heard concurrent with an object
moving at speed many kilometres away, but scientists now believe this to be
what they term an electrophonic effect.

It is possible that the twisting wake of a fireball might trap a magnetic
field, creating very long radio waves that travel to the ground at the speed
of light. The waves then interact with almost any object to produce a sound
audible to the skywatcher.

Copyright 2000, BBC


From The Independent on Sunday, 15 October 2000

By David Keys, Archaeology Correspondent

15 October 2000

Scientists are unearthing the long-lost secrets of Britain's own Atlantis -
a vast area of former dry land under what is now the North Sea.

The investigations are revealing how ancient Stone Age communities were
wiped out by a series of apocalyptic floods which, scientists believe, are a
stern warning of the devastation that global warming and rising sea levels
can cause.

After the last Ice Age, melting ice caused the southern half of the North
Sea to rise by some 65ft in 2,000 years, submerging an area in the North Sea
the size of modern Britain.

But researchers at Durham University have now established that Britain also
suffered a series of shorter term but catastrophic floods with terrible
effects on human communities, killing 2,000-3,000 people at a time.

Whereas populations were able to adapt to long-term sea level rise, they
would have been unable to escape from the periodic super-floods which
resulted from it.

There were periods in which very large flat areas became vulnerable to tidal
surge inundation for several hundred years before becoming permanently

Between 7600 BC and 5900 BC around 1,000 square miles of North Sea region
dry land would have been overwhelmed by 15ft-high tidal and storm surges on
average four times a century - once a generation.

Due to the concentration of human hunter-gatherer activity in food-rich
coastal and estuarine areas, such surges would probably have drowned up to
2,000 people each time.

The geographical spread of these flood disasters has been calculated by a
team of paleogeographers from Durham University who have just completed a
survey of the drowning of the North Sea region.

Most of this 100,000 square mile British Atlantis was there in 8000 BC and
gone by 6500 BC. By then only a 140 mile long, 5,000 square mile island,
where the Dogger Bank is now, survived.

This flooding was a pivotal event in British prehistory and Britain's status
as an island dates from this time. The initial consequences were
technological, cultural and perhaps even genetic. The introduction of new
continental weapons technology - new forms of arrow heads - was delayed for
2,000 years. And subsequently the introduction of agriculture and monumental
architecture was delayed for 1,000 years.

By ensuring that Britain lagged behind the continent, the drowning of the
land-link was the cause of a pre-historic "two-speed" Europe.

Scientists involved in the research believe that, as well as helping us to
understand the past, their work also acts as a warning for the future.

Dr Ben Horton, a leading member of the University of Durham's Sea Level
Research Unit, said: "Our investigations have revealed for the first time
that large areas of land can be flooded very rapidly.

"As our climate and oceans respond to global warming, there will be
potential for global sea level rise on a massive scale."
Copyright 2000, Independent on Sunday

MODERATOR'S NOTE: Once again, I should caution readers against attempts to
compare Ice Age conditions with possible effects current climate variations
may have on sea level change. One should remember that during the last Ice
Age the northern regions of Europe and the British Isles included mile-thick
ice caps. The "apocalyptic floods" refered to by the Independent are simply
a demonstration that increased land-borne ice equates to lower sea levels
and vice versa. To suggest that we might experience similar flood
catastrophes in the near future due to the current  warming trend is
environmental scare mongering that is not based on any sound evidence.


From Piazzi2001 <>

Palermo, 11-16 June 2001

Organized by
Osservatorio Astronomico di Palermo
Dipartimento di Scienze Fisiche e Astronomiche dell'Universita` di Palermo
Dipartimento di Fisica e Astronomia dell'Universita` di Catania
Osservatorio Astrofisico di Catania
Osservatorio Astronomico di Torino

Scientific Organizing Committee (SOC)
M. A. Barucci (France), R. Binzel (USA, Co-Chairman), C. Blanco (Italy),
A. Carusi (Italy), C. Chapman (USA), B. Clark (USA), P. Farinella (in
memoriam), S. Isobe (Japan), D. Lazzaro (Brazil), D. Lupishko (Ukraine), B. Marsden
(USA), A. Milani (Italy), K. Muinonen (Finland), G. Neukum (Germany),
V. A. Shor (Russia), D. Yeomans (USA), V. Zappala' (Italy, Co-Chairman)

Local Organizing Commitee (LOC)
C. Blanco (Co-Chairman), R. Candia, I. Chinnici, L. Daricello, M. Di Martino
(Co-Chairman), G. Fodera`, A. Harris, G. Inzerillo, G. Liggio, D. Randazzo, D.Recupero, L.
Santagati, S. Serio (Co-Chairman), G. Vitale


The International Conference "Asteroids 2001: from Piazzi to the 3rd
Millennium" will be held in Palermo from 11 to 16 June 2001, to celebrate the 200th
anniversary of Giuseppe Piazzi's discovery of 1 Ceres from the tower of Palermo Observatory
on January 1st 1801. It aims to present the current understanding of asteroids
science. The main topics will concern the main belt asteroids with single sessions
devoted to the interrelationship with Kuiper Belt and Near-Earth Objects.

The Scientific Organizing Committee has proposed the following tentative programme:

1. History
2. Ground-based observations: techniques and reports of results
3. Space-based observations
4. Composition and physical structure
5. Asteroid families and collisional processes
6. Interrelationships with inner SS objects: NEOs, Meteorites, Meteor streams
7. Interrelationships with outer SS objects: Trojans, Centaurs, Edgeworth-Kuiper objects, Comets
8. Dynamical structure
9. Inventory, origin, evolution, etc.

This program will develop through the presentation of invited, contributed
and poster papers to be published in different books or journals. In addition, the
Conference Asteroids 2001 will bring together authors for the Space Science Series book

"Asteroids III", that will be published by the University of Arizona Press.
Further details and separate invitations for input and contributions to the book are

Registration fee
A registration fee of Lit. 650.000 (approx. 340 EU), students Lit. 250.000
(approx. 130 EU) will be charged to early participants. The amount includes a copy of the
book "Asteroids III", a welcoming reception, a half-day excursion (inclusive of dinner), the
closing dinner and other events.

Grants and exemption from the registration fee depend on the availability of
funds.Instructions on how to pay the registration fee prior to the Conference
(normally by credit card), will be given in the second announcement.

The Conference will take place at the Hotel Zagarella & Sea Palace in Santa
Flavia, a small sea-side resort town about 25 km east of Palermo. We have booked a
block of single and double rooms at this hotel at a reduced rate. Prices per night ,
inclusive of breakfast, will be Lit. 120.000 in single room, Lit. 160.000 in double room for single
occupancy and Lit. 105.000 per person in double room. For half board accommodation a
supplement of Lit. 40.000 per person must be added.

Additional information
Further information on the social programme and instructions for registration and logistics
will be supplied in the second announcement, due around January 2001. It
will include more details of the scientific programme and invited speakers.Hotel and registration forms will
also be distributed with the second announcement, as well as being available
through the web at

As the web site will be regularly updated, we suggest that you visit it
The second announcement will be sent only by e-mail.

We are looking forward to seeing you in Palermo.

Carlo Blanco    Mario Di Martino Salvatore Serio
on behalf of the Local Organizing Committee

Scientific Organizing Committee Contact address:
Carlo Blanco, Luigia Santagati
Dipartimento di Fisica e Astronomia dell'Universita' di Catania
Via S. Sofia, 78
95125 Catania Italy
Tel.: 095 73 32 245/269 ; Fax: 095 33 05 92

Local Organizing Committee Contact address:
Donata Randazzo, Laura Daricello
Osservatorio Astronomico di Palermo
Piazza del Parlamento 1
I-90134 Palermo, Italy
Tel.: 091 233 243 / 247; Fax: 091 233 444




From Brigadier General Simon P Worden, AF/XOC


Very illuminating discussion concerning the UK Task Force report. I would
certainly agree that the UK Task Force has done a tremendous service in
outlining a superb approach -- including in my opinion the Southern
Hemisphere Observatory.  However, I note several commentators have
questioned the cost-effectiveness of or need for space-based observatories.
As a strong advocate for space-based asteroid research I must differ with
both David Morrison's and David Tholen's claims that satellite-based
telescopes are not cost-effective and not needed.  First, space-based
telescopes are necessary to observe close to the sun due to scattered-light
problems. As Dr. Tholen points out, ground-based searches here are
difficult at best. But both commentators seem to miss our requirement to
detect potentially threatening comets coming from the solar direction.
Second, and more important is the misconception that space-based
observatories are expensive. I submit information on the proposed Canadian
Near-Earth Surveillance System (NESS).

This satellite will cost in the range of $3-5M -- comparable to a
ground-based telescope. And NESS can be launched as a secondary payload for
less than $1M.  Although some have criticized its small aperture, it does
have the ability to detect much fainter objects near the sun than any
ground-based system and can serve as a prototype for larger aperture systems
hosted on similar low-cost, lightweight "micro-satellites."  Finally, since
NESS is a "dual-use" proposal with earth-orbiting satellite tracking
functions, its very modest cost will be covered in good part by national
security resources.  I also attach a file with more detailed technical
information on NESS.

I hope that my astronomical colleagues realize that there is a revolution
occurring in our ability to perform low-cost missions in space -- including
both surveillance and in-situ asteroid studies.  I commend the UK NEO Task
Force for pointing this out.

S. Pete Worden, Brigadier General, USAF

MICROSATELLITE.  A.R. Hildebrand (1), K.A. Carroll (2), D.D. Balam (3),
J. M. Matthews (4), R. Kuschnig (4), P.G. Brown (5), E.F. Tedesco (6)

1 Department of Geology and Geophysics, University of Calgary, 2500
University Drive NW, Calgary, AB, T2N 1N4 (
2 Dyancon Enterprises Ltd., 3565 Nashua Drive, Mississauga, ON,
  L4V 1R1(
3 Department of Pysics and Astronomy, University of Victoria, P.O. Box 3055,
  Victoria, BC, V8W 3P6 (
4 Department of Physics and Astronomy, University of British Columbia, 6224
  Agricultural Road, Vancouver, BC, V6T 1Z1
5 Department of Physics and Astronomy, The University of Western Ontario,
London, ON,
N6A 3K7 (,
6 Terra Systems, Inc., Lee, New Hampshire, USA 03824

Introduction: In the closing decade of the twentieth century asteroid and comet
discovery, tracking, and characterization have attained levels of interest and
committed resources previously unparalled.  This is due in large part to the level
of respectability that the impact hazard has attained, but also reflects fundamental
interest in the small body population of the solar system and the perceived usefulness
of asteroids and (extinct) comets as exploitable resources. The respectability of
studying this population was also reflected by spacecraft missions which began to
include asteroid or comet encounters, or were dedicated to their observation. Asteroid
and comet sample return missions are imminent.  With the exception of some experimental
work, all small body discovery and tracking work has been ground based, although
consideration and tests of what may be achieved with a space based detector
have begun [1,2].  The  Near-Earth Space Surveillance (NESS) Mission, a microsat dedicated to observing
near-Earth (NEO) and interior-to-the-Earth (IEO) asteroids and comets plus artificial
satellites, is currently being studied under contract to the Canadian Space

Science Goals: The primary science goal will be to discover and derive orbits for enough
IEO's to establish the population's dynamical characteristics to closer than 0.387 AU
(Mercury's mean solar distance); this observing program will also add significantly
towards delimiting the larger members of the Earth-crossing Aten class of NEO's. 
Pointing near the Sun will be limited by the capability of the baffle system, but an
interior-to-Mercury small body population (vul-canoids) may also be sought if the
spacecraft orbit has suitable eclipse geometry to allow significant observing time at
near-Sun angles.  The spacecraft will carry spectral measuring capability, probably in
the form of a filter system, and the NESS mission will provide sufficient taxonomy of
discovered objects to characterize the population and determine object sizes. Defining
the IEO population will provide constraints towards understanding the evolution of Venus
and Mercury.  For example, establishing the impactor flux and types at both Venus and
Mercury will allow refining the age of the Venusian surface, and determining the rate
of volatile delivery to the surface of Mercury.

Mapping a fraction of the IEO population and Aten-class objects now unobservable
from Earth's surface will leverage science opportunities.  For example, missions to
the inner planets, such as Messenger to Mercury, will have more potential fly-by
opportunities en route, and small body radar imaging/reflection opportunities will
be available in the sunward hemisphere of the Earth.  As well, the ability to obtain
astrometric observations of any NEO at any time will allow improvement of ephemerides
for any fast moving object to enable radar or other observations without the limitations
of ground based systems.  Finally, NESS will discover comets either unobservable, or
earlier than may be observed, from ground based platforms.  Cometary behaviour may
also be tracked substantially inwards of the Earth's orbit depending upon a comet's
orbital geometry relative to that of the Earth.  

Artificial Satellite Tracking: Satellites are tracked to provide ephemeris information
in support of mission operation functions, such as pointing high-gain ground station
antennas, and on-board determination of magnetic field strength/direction for attitude
control/estimation purposes. They are also tracked to predict and avoid potential
satellite collisions.  NORAD uses satellite tracking data to distinguish satellites
from ballistic missiles.  The Canadian Department of National Defence (DND), as part
of Canada's contribution to NORAD, plans to develop an operational space-based tracking
system.  While satellites in low Earth  orbits are efficiently tracked using ground-based
radars, optical tracking has advantages for satellites in higher orbits (e.g., geostationary
or Molniya orbits).  NESS will demonstrate satellite tracking technologies
from a microsat platform.

Advantages of an Orbital Platform: Optical search and tracking for both asteroids/comets
and satellites is done by comparing sequential star-field images to look for (typically
faint) moving objects.  Performing these observations from a space-based observatory
offers operational advantages, such as continuous duty cycle, avoidance of weather/clouds,
and reduced scattered light from the Sun, Moon and Earth.  However, the relative expense
of a satellite is most justified by its ability to observe the sky close to the Sun which
is essentially unobservable from the ground.  Combining the capabilities of Earth based
searches and a spacecraft will result in mapping the potentially hazardous
Earth crossing asteroids significantly faster than ground based surveys
alone [2].

Operational modes. Reflecting the unique capabilities of an orbiting detector in its
small body observing role, NESS will primarily be deployed in observing an "optical
fence" eastwards of Earth and interior to Earth's orbit to the limit of its sunward
pointing capability.  While not limited to the eastward looking geometry, it is
convenient for the spacecraft design.  In this orientation it will perform
its discovery, astrometry and colour survey functions.  The secondary operating mode will consist of
looking at targets of opportunity such as fast movers in the near-Earth environment,
artificial satellites, or potentially hazardous asteroids (PHA's) that need lengthened
orbital arcs.  An example of a fast mover with a poorly determined orbit is 1994 NM1,
which on December 9, 1994 passed close by the Earth with an orbital solution
that allowed intersection with the Earth.

Spacecraft Design: The NESS mission is based on the spacecraft telescope and bus developed
for the MOST (Microvariability and Oscillations of Stars) mission [1]. The microsatellite
is only 50 kg in mass with dimensions of about 60 x 60 x 24 cm. The design is 3-axis
stabilized with 10 - 20 arcsecond pointing precision.  MOST carries a 15-cm aperture
f5.88 Mak-sutov telescope with a 2 square field of view.  The current design is capable
of at least magnitude 19 resolution with reasonable exposure lengths for a search program. 
The modifications required to optimize the MOST design for the NESS mission include a
baffle, on board processing capability, consideration of increasing mirror size, and
reducing the pointing wobble to sub-pixel size on the imaging CCD. The large data
quantities generated by imaging and photometry probably require increased ground
station support.  

References: [1] Carroll, K.A. et al. (in press) Proceedings 14th AIAA/USU
Conference on Small Satel-lites. [2] Tedesco, E.F. et al. (in press) Planetary and

Those interested in more technical data should feel free to contact S. Pete


From Alan Harris /DLR, Berlin <>

Dear Benny,

   In the light of Neil Bone's interesting comments on the characterstics
of the Geminid meteor stream (CCNET Letters, 11th Oct.), we should
remember that the physical properties of Phaethon, as deduced from
infrared observations, are not what might be expected of an extinct or
dormant comet.

   This was pointed out by Green, Meadows and Davies (1985, MNRAS, 214,
29p-36p) who obtained a value of 0.11 +/- 0.02 for Phaethon's
albedo. Cometary nuclei are expected to be much darker than this
(e.g. albedo of 0.04 for Halley and similar albedos found
for trans-Neptunian objects). Furthermore, the thermal inertia of
Phaethon appears to be more than 6 times that of the lunar surface
(Harris, Davies, Green, 1998, Icarus, 135, 441-450), i.e. characteristic
of bare rock, and NOT of a porous, dusty surface such as one might
imagine an extinct or dormant cometary nucleus having. So Phaethon doesn't
"look" like a dead comet (although to be honest we don't really know what
such a thing should look like...).

   These results seem to be relevant to Neil Bone's remarks:

"...Both these characteristics are, as I understand it, ascribable to
the greater density and physically 'robust' nature of Geminid meteoroids
(2gcm^3) compared with the 'dust-balls' shed by comets (0.2-0.3 gcm^3).
In the case of the Geminids, are we not dealing with rocky fragments -
for which, I agree, an ejection mechanism has to be found - and which
are quite different from those which populate cometary meteor
streams? Surely the presence of a meteor stream is not, in itself, a
reason to suggest that Phaethon was once a comet?"

   So it seems neither the astronomical nor the meteoroid evidence
supports the case for Phaethon having once been a comet. Nevertheless,
it's still a very strange beast in the asteroid zoo...

Alan Harris
DLR, Berlin

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