This is the last issue of the CCDebates before the Easter/Passover
break. I will be back in my office on Thursday, 16 April and will try
to up-date you about the ongoing events, debates and - most of all -
about new research findings.

May I wish all of you happy Easter, happy Passover & happy holidays.

Benny J Peiser


    Clark Chapman <>

    Benny J Peiser <>

    David Morrison <>

    Jonathan Tate <>

    Robert Matthews <>


From: Clark Chapman <>

Benny --

I appreciate your questions and will try to answer them.  (I have just
returned from a trip, and must be brief.)

(1) Let me rephrase, your question before I answer it. The calculations
of the miss-distances (prior to receipt of the 1990 data) are in rough
agreement. (Note that the 0.002 AU distance of Marsden was a separate
estimate of the maximum miss-distance, an estimate of error in his much
closer miss-distance.) Do I believe that these were NOT hazardous.
Absolutely. The reason is because the nature of the data and the
extrapolations to 2028 (and the associated errors) do NOT cluster
around the Earth. Here is a schematic diagram:

                     /all possible passes are along this line
                    /                     Earth
                   /                          \
                  /                            O
                 /   (virtually zero chance of passing in this space)
     ^                              o            ^
    actual pass                    Moon    early calculation

The error ellipse is long and skinny (shown as a horizontal line
above), more than a 1000 times longer than wide.  So while the 1990
data pushed the miss-distance far to the left, there is essentially NO
error in the vertical direction so the correct calculation of IMPACT
PROBABLITY (which is what we are worried about) wasn't affected at all
(well, perhaps, a tiny epsilon) by the new data. I have every
confidence that, once things cool down, Brian will agree with all of
his other colleagues that there was no more danger in the data
available March 11th than when the 1990 data are included.  The hazard
remains essentially what it was:  extremely, negligibly tiny.

(2) Do I believe that Marsden should have informed the public if such
calculations by his colleagues were available? Absolutely. A scientific
concept goes from something thought about in the shower, to something
done on the back of an envelope, to something calculated with a
well-tested comuter program, to a conclusion discussed and reviewed by
other experts. That process could take a day or take months. What I
oppose, is release of ill-formed, casual, incomplete, unverified
calculations.  In the case of 1997 XF11, I think that the entire
process could have been completed in a day or two. As soon as there is
consensus (not necessarily unanimity) that there is a valid scientific
result of importance, the public should be informed.  In this case,
outside of the glare of publicity, I think (and hope) the calculations
and interpretation of them are sufficiently obvious to the experts that
they would AGREE that there was absolutely nothing hazardous about
XF11, no matter where the data happen to fall along the error ellipse. 
Remember, a nominal calculation of a closer approach is not at ALL more
dangerous than a distant pass.  As an analogy:  you are no more likely
to be hit by a train if you are 100 feet away from the railroad track
than if you are 1000 feet away, because the train is confined to run on
the track. 1997 XF11 is confined to run along the very skinny error
ellipse, and never could have run into the Earth on the basis of the
original data. Brian, I'm sure, will eventually agree to this.

(3)  My personal view is that observations collected from the world's
amateur and professional astronomers should be available to them.  I
think it is good that the MPC sifts through data and publishes
qualified data. But if it is almost as simple to put out the raw
observations, and (a) the observers agree and (b) other astronomers
feel they can make use of the data, I don't see why they should be held
onto by the MPC for private research. But so long as Brian agrees to
release the NEO data, than that is sufficient for NEO purposes and the
issue of "other" data can be dealt with in other forums.

(4) In question 4, you express worries about a U.S. governmental agency
serving as arbiter, especially under circumstances where agreement may
not be reached for a much longer time than would have been the case for
1997 XF11. I totally share your concern. I think that if a confusing or
debatable circumstance should arise that can't be solved by the experts
within a very few days, they should agree on where they differ and go
public. Furthermore, I think it is totally inappropriate for an
international entity like the MPC to be beholden to the rules of an
agency of a single government. All I was doing was stating the reality:
so long as NASA is the only one that pays, the MPC will have to obey
the rules attached to the NASA funding. My own view is that the
leadership of NASA is extremely open to joining with a consortium of
funding agencies and abiding by whatever agreements can be worked out
internationally regarding the operation of the MPC. The current
guidelines are interim ones only, and all possible efforts should be
made to expand the oversight of the MPC (and its funding) to be
international. I hope my last statements answer your point (5). 

Clark Chapman


From: Benny J Peiser <>

Dear Clark

Thank you for your clarifications which are much appreciated. I must
admit, however, that your answers to my questions came as a complete
surprise and have confused me even more.

Let me recall: the whole 1997 XF11 started when you (and some of
your colleagues at JPL/NASA) openly accused Brian Marsden for not
having categorically stated on 11 March that this asteroid was "NOT
hazardous". As far as I can see, that is the bottom line of your
accusations and campaign.

I therefore asked you whether - on the basis of the data available on
11 March - it would have been scientifically accurate to make such a
sweeping and absolute statement.

What has really confused me is that you give three different answers to
this essential question.

The first clarification doesn't really answer my question since you
simply state that "these calculations [...] were NOT hazardous". Of
course they weren't.

In point two of you clarification you then stress your firm believe
that NEO experts "would AGREE that there was absolutely nothing
hazardous about XF11". I guess the phrase 'absolutely nothing' is even
more re-assuring than 'NOT hazardous'.

But then, at the end of your answer to question one, you come to a
remarkable conclusion which throws your entire argumentation and
accusation into question:

I quote: "The hazard remains essentially what it was: extremely,
negligibly tiny".

Now this curious sentence reminds me of the joke about being just
negligibly, tiny wee-bit pregnant (but not to worry). Are your really
aware of the implications of your statement? Isn't it almost
word-for-word identical to what the IAUCircular and press information
was saying on 11 March 1998 (i.e. that a future hazard cannot be
ruled out  a b s o l u t e l y  until more data is available)?

I leave it to the scientific community and the interested public to
answer this question. But I do start wondering whether you might have
violated the interim NASA guidelines on public announcments regarding a
PHA since your statement includes a "disquiting prediction" (at least
some anxious people will interpret it as such) about the existence of a
p o t e n t i a l hazard.

With best wishes, Benny


From: David Morrison <>


Let's see if I have this right: If Brian Marsden on his own personal
judgement choses to hold back on posting the asteroid observations
(sent to him from around the world) thus denying or delaying their
access to the community, this is good, but if NASA (as the funding
source for much of the Minor Planet Center) requires Marden to post the
observations within 24 hours this is government interference and
jeopardizes the impartial role of the MPC in collecting international
observations.  Interesting.


Dear Dave, I appreciate your concerns. Can I kindly refer you to
Clark's remarks in point three of his statement which I generally
share. Benny


From: Jonathan Tate <>

Dear Dr Morrison,

I have been reading, with interest and increasing despair, the voluminous
mail that has been posted on the role of the MPC in general, and the actions
of Brian Marsden in particular. Please understand that I hold all of the
protagonists and contributors in the highest respect. However, as someone
who spends considerable time briefing members of the public, and, at times,
the media on the subject of impacts, and given my background, I find the
controversy discouraging. There are a couple of points that seem to me to be
relevant in this instance:

1. The XF11 occurrence was abnormal, and unprecedented in its scale and
effect. Whether or not mistakes were made is not an issue – who amongst us
would be arrogant enough to claim to be infallible?

2. Is it proper, in a "public" forum (I have already been asked to comment
by members of the press), to fling accusations around concerning the lead
personalities in the field? This, I would beg to suggest, is in danger of
becoming more damaging to the NEO community than the original handling of
the XF11 incident which has, despite everything, been an eye-opener for the
general public. Certainly the feedback that I am getting is that few people
are going to be impressed by the arguments of a group that is at war with
itself. Sometimes personal issues should take second place to the overall
cause. The NEO threat is just beginning to emerge into the public
consciousness, and the very last thing that we need now is internal dissent.
If we want recognition and funding, we must avoid handing ammunition to
those who wish otherwise.

3. Can the system be improved to avoid future incidents? Of course it can –
no system is perfect. The MPC works and is held in high regard
internationally, as are the personalities involved. "If it ain’t broke,
don’t fix it". But, and it is a big "but", if it is, let’s fix it in a
professional manner. However, anything that smacks of national domination,
by any nation, would be contrary to the spirit of the entire field of study.

4. In the UK we are fighting hard, with some success, to achieve
recognition, and funding for NEO studies, including amongst other things,
the UK Schmidt Telescope project. To do this we need the support of three
groups of people, the scientific community who advise the politicians, the
general public who vote for them, and the politicians themselves who hold
the purse strings. This argument is rapidly unravelling the web of support
that we are trying to weave, and this must be the case worldwide.

By all means let’s change the MPC’s modus operandi if necessary, but please
let’s do it without internecine bickering that makes us all look foolish.

Yours sincerely

Jay Tate
Spaceguard UK

I wholehartedly support Jay Tate's appeal to NEO researchers to refrain
from any personal attacks directed against honourable and highly
respected members of the scientific community. As the moderator of the
CCNet, I have been trying - as best as I can - to keep the necessary
and inevitable debate about and re-assessment of the handling of XF11
as objective, impersonal and decent as possible. Please believe me when
I tell you that I had to reject a number of comments from distribution
which were either too impolite, too personal or included
unsubstantiated accusations. I sincerely appologise to all list members
if I failed to uphold this sense of decency on a couple of occasions.
It is my intention to continue in my attempt to uphold a high standard
of fair and courteous communication on this network and hope that all
list members will appreciate and keep these requirements.

Benny J Peiser


From: Robert Matthews <>

Dear Benny

There doesn't seem to have been much (or indeed any) contribution from the
credulous and stupid mass media to the 1997 XF11 debate as yet, so as a
fully qualified member of the same, I wonder if you'd permit me to make a
couple of points?

1. It's a curious fact that scientists are not unique in preferring
well-attested facts to dodgy preliminary estimates. Even some
journalists like to get stories right every now and again, and to have
them based on sound information that has a shelf-life of longer than 24
hrs.  Quite apart from wanting to serve our audience as best we can,
reporters know that they can push news editors too far with "Asteroid
on collision course" stories that (mercifully) turn out to be baloney.
There comes a time where even the people with the green eye-shades and
cigars say "Oh yeah - just like last time, right?", and stick the story
straight on the spike.

2. In terms of how the astronomical community should deal with potential
impactor stories, I wonder if there is anything to be learned from the way
civil aviation officials deal with near-miss stories ? These scare the hell
out of holidaymakers when they are announced, and so presumably they are
checked out pretty thoroughly first before being released to the media. 

For fellow hacks who see this as an outrageous call for censorship, I
should perhaps add that I'm merely suggesting that a few days'
fact-checking by the astronomical community before it says anything may
serve to protect against our reporting preliminary, terrifying yet
incorrect scientific results, whose true nature can be ascertained in a
matter of days rather than years.

As a bonus, allowing the astronomical community a few days to check its
work should cut the number of times scientists blame the media for
"misreporting" or "hype", while conveniently forgetting that it is they who
gave us the information and quotes in the first place.

Robert Matthews, Science Correspondent, The Sunday Telegraph, London, UK

CCCMENU CCC for 1998