CCNet 23 August 1999: TORINO SPECIAL

    Benny J Peiser <>

    MODERN ASTRONOMER, August 1999

(3) NEO News (8/20/99) TORINO SUMMARY
    David Morrison <>

    Don Yeomans, JPL, IMPACT Meeting Co-Chair

    Richard Binzel, MIT

    Brian G. Marsden <>
    Gareth V. Williams <>

    Kieffer-Olsen Jens <>


From Benny J Peiser <>

This issue of the CCNet includes more reports and statements on the
Torino IMPACT meeting, its results and recommendations. Regrettably, an
error has slipped in the "Torino Impact Meeting Recommendations", as
circulated by David Morrison in his NEO News last Friday - see items
3 to 5 below. This mishap may have happened inadvertently, but the
inaccurate information included in this document should be corrected by
the meeting's scientific committee in due course.

The incorrect detail can be found in the first paragraph of the

     "Recognizing the importance of the free exchange of data for NEO
     research but acknowledging the need for suitable funding and a
     smooth transition from the current situation, the Minor Planet
     Center (MPC) should move rapidly toward the following goal: All
     data sets of the MPC should be generated, updated and freely
     distributed in near real time (i.e. within minutes of data receipt
     at the MPC) unless an observer has requested that the MPC validate
     that observer's data before making these data public".

As a participant of the meeting, I wish to point out that this
particular "recommendation" was not agreed by the IMPACT meeting. In
fact, the proposal for such a recommendation was put to the vote but
failed due to a lack of support. Since none of the motions related to
the working of the MPC found a majority, the whole issue was declared
indecisive and skipped altogether.

In his report from Turin [see (1) below], Jay Tate, director of
Spaceguard UK and one of the delegates, also stresses this point:
"Professor Ted Bowell proposed changes to the MPC that were highly
controversial, raising questions of control and IAU international
control. No consensus was reached on this, but the role and impartiality
of the MPC is unlikely to be seriously challenged."

Other participants I have contacted confirm that the recommendation in
question was not accepted at the meeting. In view of the apparent lack
of consensus within the NEO search community on this issue, and given
that the proposal in question was actually voted down by the
participants of the IMPACT meeting, it should be withdrawn from the
final document.

Benny J Peiser


By Jay Tate, Spaceguard UK

The IMPACT ("International Monitoring Programs for Asteroid and Comet
Threat") workshop was held in Turin, June 1-4, 1999. This meeting was a
follow up for the International Astronomical Union Working Group on
Near Earth Objects sponsored workshop on the island of Vulcano (Italy)
in September 1995, that was entitled "Beginning the Spaceguard Survey".
The aim of that workshop was to emphasise the need for a co-ordinated
effort to detect Potentially Threatening Objects (PHOs), and to
establish the basis for effective international co-operation on the

The IMPACT workshop was sponsored by, amongst others, the IAU, ASI,
NASA, ESA, Spaceguard Foundation and The Planetary Society.
Participation included a high proportion of the world's expertise in
Near Earth Object (NEO) studies, and high ranking members of NASA, the
IAU and other sponsoring organisations.

The objectives of the workshop were:

* To encourage scientists in all nations and their sponsoring
agencies to increase NEO search and follow-up efforts.

* To improve communications among observers world-wide and to use
these improved communications to foster co-ordination of search and
follow-up activities.

* To assess the actual potential and limitations of ground-based
observing facilities, and to discuss the possible role of space-based
segments in NEO search.

* To develop procedures for assuring a rapid communication of
accurate information about Extremely Hazardous Objects which may be
detected in the future.

* To draft and discuss Recommendations to be distributed to the
scientific and political bodies able to support and fund NEO researches.

The structure of meeting was to hold an initial plenary session during
which the conference was briefed on a number of topics, to bring
everyone fully up to date with recent developments. After the briefings
the conference split up into four sub-groups to discuss specific issues,
and to produce recommendations to be passed to the IAU and the
forthcoming United Nations UNISPACE 3 conference in July. These
recommendations, once agreed by the sub-groups were then discussed at
another plenary session where they were agreed by the floor, or
rejected. While it is not yet possible to detail the final
recommendations that will be passed to the IAU, as they have to be
"word-smithed" by the sub-group chairmen and agreed in their final
forms, it is possible to list a few of the significant statements made,
discussions had and recommendations made.

It is clear now that actual asteroid impacts are likely to be preceded
by a number of close approaches as the asteroid orbits the Sun. This
means that, with a robust detection system and suitable follow-up
observations we should be able to get plenty of warning before an actual
impact occurs.

Comets pose a much smaller risk than asteroids. The effects of a
cometary impact will be just as if not more severe as those resulting
from an asteroid collision, but they occur much less frequently. Also,
long period comets are unlikely to be discovered much before two years
before impact, so the question of mitigation becomes much more
difficult. This is because, while the vast majority of asteroids orbit
the Sun close to the plane of the Solar System, comets can approach from
any direction. To detect such wild cards the volume of sky to be
searched would be enormous. The bottom line is that, with current
technology, it is unlikely that we would discover a dangerous comet in
time to do anything about it.

The issue of whether asteroids are "rubble piles", loosely held together
by gravity, or solid bodies is still unresolved. The data from the few
asteroids that have been closely studied seem to give differing results.
While there is no reason to think that all asteroids are the same, a
clear picture of the physical properties of asteroids is very necessary
before any deflection or disruption strategies can be developed. We will
need access to 4 to10-metre class telescopes to do detailed
compositional studies on NEOs.

Dr. Alan Harris of JPL estimates that about 18% of 1 kilometre and above
sized NEOs have been discovered, but there are large population
uncertainties. However, even with detection systems such as LINEAR, NEAT
and Spacewatch, we are still discovering asteroids at far too slow a
rate. To achieve the NASA goal of detecting 90% of all Earth Crossing
Asteroids (NEAs) larger than1 kilometre in diameter within 10 years, we
need to increase the detection rate by 8-20 times.

There are currently a large number of space missions to asteroids and
comets such as NEAR, Stardust, Rosetta and Space Technology 4 (formally
Deep Space 4). This is a "Golden Age" for studying comets and asteroids
according to Don Yeomans, the Director of the new NASA/JPL NEO Project

Japan is pressing ahead with its new NEO detection programme. Dr Syuzo
Isobe, the project leader, told the meeting that work is proceeding well
on the new Spaceguard Japan telescope which should be on-line by the end
of this year. The primary function of the main 1-metre wide field (3
degrees) instrument will be NEO detection, but it will also be used for
25% of the time on space debris studies. The secondary, 0.5-metre
telescope can be used for follow-up observations. The project has been
largely funded by the Japanese government to the tune of $6 million
(about 4 million).

One of the sub-groups developed a protocol, primarily for IAU purposes,
dealing with the public and media announcement of PHOs. In the plenary
session there was some confused discussion, and eventually a shorter
agreed document was approved. This emphasised the need for individual
nations to discuss the issue and to decide what information the public,
politicians and decision-makers require. The need for a National
Spaceguard Centre in the UK is obvious. The efforts of British
researchers like Professor Mark Bailey, Dr Duncan Steel, Professor Iwan
Williams and Spaceguard UK were applauded, but it was clear to all that
we need increased government interest here in Britain. It was noticeable
that there were no representatives from any British government
department present at the workshop. Recent events have shown that there
is official acceptance of seriousness of problem, and in the UK we have
a wealth of experience that is the envy of the world. The international
consensus was that the UK could take a world lead in NEO studies if only
we had a smattering of support at government level.

There is an urgent need for systematic, professional follow up
programmes, and more funding (staff) for the Minor Planet Centre.
Professor Ted Bowell proposed changes to the MPC that were highly
controversial, raising questions of control and IAU international
control. No consensus was reached on this, but the role and impartiality
of the MPC is unlikely to be seriously challenged.

The possibilities of collaborative European programmes were discussed
(DLR, ODAS, including the use of ESO facilities), but the general
feeling was that, without someone taking a leadership role, little was
likely to happen due to lack of funding.

Sub-Group 4 prepared recommendations on political support that were
designed to be passed on to the IAU and the United Nations. The key
recommendation from the workshop was passed almost unanimously and reads
as follows:

Statement of the participants at the Torino Meeting

"International Monitoring Programs for Asteroid and Comet Threat"

1-4 June 1999


* that cosmic impact is a significant low-probability,
high-consequence phenomenon that could affect civilization or life on

* the existence within Europe of considerable expertise in the
subject, and of national centres of excellence in minor body research;

* the requirement to implement an effective monitoring system for
Near-Earth Objects (NEOs), including their discovery, astrometry,
physical characteristics and dynamical behaviour;

* that a start has been made towards establishing an international
Spaceguard programme;

Recommends that European governments should:

* establish national Spaceguard centres to advise their
governments on the assessment of the impact hazard and to act as foci
for NEO research;

* support these centres financially to facilitate European
collaboration in the international Spaceguard programme.

The message to governments should be clear.

The importance of precoveries and photographic plate searches was
stressed. It was just this technique of searching old plates for
asteroid trails that enabled astronomers to rule out a collision with
asteroid 1997 XF11. There was some emphasis on UK Schmidt Telescope
plate archive currently located at the Royal Observatory, Edinburgh, and
this would also be an obvious role for the National Spaceguard Centre.

Professor Rick Binzel discussed his new hazard scale, similar to the
Richter Scale used for earthquakes. This "Turin Scale" will doubtless be
published, and has considerable merit as a tool for briefing the press.
However, it must be understood that the status of an object can change
as its orbit is refined, or it is perturbed on its travels. It was
pointed out that J. Tate had already produced something broadly
acceptable for UK purposes, and that the "Turin Scale" might be a little
too simplistic. Dr. David Morrison of NASA observed that "people just
don't understand probability", and he is quite right. Not only are
statistics difficult to come to terms with, but, with asteroids, the
goal posts are constantly shifting.

Finally, with much panache, Dr. Andrea Milani announced a 10-7 impact
probability for asteroid 1998 OX4 in Jan 2046, based on observations up
to 4 Aug 1998. However, this object has already probably been lost
because of the lack of follow-up observations.

To summarise, the three key points to emerge from the workshop were that
we have to do better detecting NEOs, but that there is little point
concentrating on detection without comprehensive follow-up programmes to
establish accurate orbits for the discovered objects. Finally, national
governments must "get their acts together" otherwise the entire field
will be dominated by the USA, and they cannot do it all! The next time
that an 1997 XF11 or 1999 AN10 comes along, are we to depend on a
foreign government department to tell us about it?

JAY TATE Tate is the director of Spaceguard UK, a member of the Board of
Directors of the international Spaceguard Foundation, a consultant to
the IAU WGNEO, an associate of COSPAR and a fellow of the Royal
Astronomical Society.

Copyright 1999, Modern Astronomer

(3) NEO News (8/20/99) TORINO SUMMARY

From David Morrison <>

Dear Friends and Students of NEOs:

Following are several reports that summarize the June meeting in Torino
on International Monitoring Programs for Asteroid and Comet Threat
(IMPACT). These are:

* Overall meeting report by Mark Bailey (from Astronomy & Geophysics)
* Meeting highlights by David Morrison
* Statement of conclusions and recommendations by Don Yeomans
* Draft IAU plan for rapid peer review of impact predictions
* Description of the Torino Impact Hazard Scale by Rick Binzel

I believe it may be useful to have all of these reports gathered
topgether in one place.

Also, I apologize for writing the wrong month in yesterday's NEO News,
which should have been dated (8/19/99)

David Morrison


Mark Bailey's report from the IMPACT meeting, Turin 1-4 June
[as posted on CCNet 19 August 1999]


By David Morrison

Note: The official output (resolutions) of the IMPACT meeting are
provided by Don Yeomans in the article following this one.

* Nature of the Impact Hazard: For any given size (energy) of potential
impactor, there is a "background probability" of impact from unknown
objects. As more NEOs are discovered, this background probability
decreases. However, occasionally a newly discovered NEO is found to be
on an orbit that repeatedly brings it close to the Earth, and that has
a non-zero chance of impact at one or more discrete times in the
future. As the orbit is refined, these discrete moments of risk will
generally disappear. There are no more than a handful of truly
threatening NEOs (D >1 km) in any century, and perhaps none.  The
progress of Spaceguard can then be thought of as a replacement of a
general background risk with discretely identified risks from a very
small number of NEOs, which will of course be carefully tracked to
determine their future orbits with high precision.

* Appreciation of the Risk: Although the public is broadly aware of the
impact hazard, and there has recently been evidence of increased
interest in the U.S. Congress and the UK Parliament, it appears that
the reality of the impact hazard has still not been accepted by many
decision-makers, including most professionals in the risk assessment
profession. Geof Sommer of RAND provided the workshop a provocative
discussion of how we might formulate some of our issues in terms that
can communicate better with policy makers and perhaps enhance the
credibility of NEO impacts as a risk issue.

* Search and Discovery: The rate of discovery of NEAs has greatly
accelerated, with the bulk of the recent discoveries coming from the
MIT LINEAR program using a single 1-m telescope.  Grant Stokes reported
that a second identical LINEAR telescope is about to begin regular
operations, and other systems are also working, as described in
previous NEO News notes. However, to meet the Spaceguard objective of
discovering 90% of NEAs >1 km in diameter by 2009, it will be necessary
to extend the search down to visual magnitude 20.5, which has not been
demonstrated for LINEAR or other systems that use 1-m telescopes.  Thus
it is not yet clear whether an expanded network of 1-m telescopes can
do the full job.

* Follow-up Observations: NEA discoveries must be rapidly followed up
to determine orbits.  Many groups, including amateur astronomers, now
contribute to follow-up observing programs.  This work is quite
effective, but most of the present observers do not have large enough
telescopes to observe discoveries that reach to magnitude 20.5.  Thus
as the discovery rate of faint NEAs increases, there may be a crises in
follow-up.  We also lack follow-up capability in the Southern
Hemisphere, which could lead to the loss of many NEAs that are moving
south at the time of discovery.

* Availability of data: As the number of NEA observers increases, and
as more people have the capability to calculate orbits and impact
probabilities, it is essential to move toward more rapid dissemination of
data on NEA positions. Probably a system can be developed soon to
provide automatic, essentially instantaneous posting of observational
data on the Internet.

* Cooperation and Coordination: A successful Spaceguard program
requires detailed coordination of observations to avoid redundancy and
make full use of the available resources. Some observers are already
posting their observing plans on the Internet. Better coordination will
be required, however, as the rate of discovery continues to increase.

* Physical Characterization: There is a continuing need for physical
characterization of NEOs, primarily using ground-based telescopes and
radar.  In addition, a number of spacecraft missions to comets and
asteroids are planned or underway, which should greatly increase our
knowledge of the nature of these objects.

* Impact Hazard Scale: A new Torino Impact Hazard Scale, developed by
Rick Binzel, was endorsed by attendees at the workshop.  This scale,
ranging from 0 (risk well below background level) to 10 (certain
catastrophic impact) is described in the final part of this edition of
NEO News.

* Verification of Threatening NEOs: The workshop attendees recommended
that the International Astronomical Union take responsibility for
establishing a system for voluntary rapid peer review of predictions or
announcements of any NEO with significant impact risk (level 1 or
higher on the Torino risk scale). The IAU proposal is included as an
Appendix in the following report from Don Yeomans.


From:    Don Yeomans, JPL, IMPACT Meeting Co-Chair

Date:    August 5, 1999

GENERAL STATEMENT of the participants at the Torino Meeting
"International Monitoring Programs for Asteroid and Comet Threat"
(IMPACT) 1-4 June 1999


that cosmic impact is a significant low-probability, high-consequence
mphenomenon that could affect civilization or life on Earth:

the existence of considerable world expertise in the subject, and of
national centers of excellence in minor body research:

the requirement of implementing an effective monitoring system for
Near-Earth Objects (NEOs), including their discovery, astrometry, physical
characteristics and dynamical behavior;

that a start has been made towards establishing an international Spaceguard

Recommends that governments should:

establish national Spaceguard centres to advise their governments on the
assessment of the impact hazard and to act as foci for NEO research:

support these centres financially to facilitate international
collaboration in the international Spaceguard program.


Noting that the world has inadequate facilities for any one group to
complete the Spaceguard Survey and noting the complexity of optimizing the
use of a wide variety of systems, the Torino workshop participants strongly
urge that the requisite effort be applied to optimize the entire set of
search and follow-up systems.  In particular, the recommendations for NEO
search, discovery, follow-up and recovery areas follows:

Search:  Now that current NEO sky searches each month are approaching
saturation for northern hemisphere observing sites, an effort should be
made to extend the search efforts to fainter limiting magnitudes.

Follow-up:  Steps should be taken to examine additional incentives for the
follow-up observations necessary to compute orbits.

Southern Hemisphere Observing: It is desirable to have southern hemisphere
NEO search facilities, and important to have southern hemisphere NEO
follow-up facilities, both professional and amateur. Recognizing the
difficult economic situation of most southern hemisphere countries, we
encourage the appropriate agencies to support national and regional efforts
to make these facilities available.

Critical observations: Access should be improved to sufficiently large
telescopes in both the northern and southern hemispheres to ensure that
NEOs are observed at subsequent (recovery) opportunities after the
discovery itself.


In view of the importance of knowing the sizes, albedos, compositions, spin
rates, shapes and bulk material properties of Near-Earth Objects, the
following recommendations are made:

More observing time should be allocated at ground-based facilities of the
appropriate type for NEO visual and near infrared spectroscopy, infrared
radiometry, photometry for light curve analyses and international radar

A study should be conducted to determine the design and characteristics of
an infrared-visual space telescope to determine the sizes, albedos, and
compositions of near-Earth objects.  This study should consider large
format thermal infrared and visual arrays, infrared thermal spectrometers
as well as the efficiency of searching for Atens and asteroids whose orbits
lie entirely interior to the Earth's orbit.  The cost-effectiveness of
space-based measurements versus ground-based measurements should also be

Additional space missions to NEOs should be undertaken to characterize this
diverse group of objects and to determine their material properties, in
particular their material strengths and moments of inertia.

A web-based database should be developed to provide information on the
physical characteristics of NEOs including the physical parameters (and
corresponding references) obtained from photometry, polarimetry,
radiometry, spectroscopy, radar techniques and from space-based


Recognizing the importance of the free exchange of data for NEO research
but acknowledging the need for suitable funding and a smooth transition
from the current situation, the Minor Planet Center (MPC) should move
rapidly toward the following goal: All data sets of the MPC should be
generated, updated and freely distributed in near real time (i.e. within
minutes of data receipt at the MPC) unless an observer has requested that
the MPC validate that observer's data before making these data public.

Pre-Discovery Data: The development of one or more plate archive search
engines is needed.  It may be necessary to offer financial incentives to
expedite the necessary measuring of these plates.

Radar Data We stress the importance of timely NEO radar observations for
the purpose of orbit improvement.  The possibility of impact could be
confirmed or ruled out with radar observations.  Therefore we urge that
radar observing capabilities be maintained and, if possible, upgraded and
extended into the southern hemisphere.

Observational Scheduling: Development and maintenance of a service for
optimizing the scheduling of observations is desirable to maximize orbit
improvement and to establish priorities for observational targets.

Orbit Computation: It is recommended that the various orbit computation
groups inter-compare their orbit solutions and uncertainty estimates.

Orbital Nonlinearity: The importance of nonlinearity in orbital uncertainty
computations and propagation is difficult to quantify.  Further research on
this topic is needed.

Analysis of Potential Threats: A computational "filter" should be applied
when a NEO orbit is established or changed.  A typical sequence might
consist of the following steps.

* Compute the MOID and its uncertainty as a function of time

* Compute all close approaches that appear to threaten the Earth and that
are consistent with the observations.  This analysis should cover a
reasonable time frame, such as the next 50 years, and allow for the
detection of cases to a probability of the order of the background rate of
undiscovered NEO impacting the Earth.

* Carefully analyze potential impacting cases

We urge that these computations always be performed by at least two
independent groups.

Initial Orbit Computation: We encourage research on the computation of
initial orbits and their uncertainties.

Comet and Asteroid Orbits: We strongly urge that additional groups compute
orbits and impact probabilities for comets.  We further recommend that
cometary nongravitational (outgassing) force models be revisited in the
light of much expanded observational data sets and improved computational
capabilities.  In addition, efforts should continue to examine the
sensitivity of asteroid orbital evolution to asteroid nongravitational
perturbations such as the Yarkovsky effect.


The Torino IMPACT Workshop recommends that a voluntary process be developed
under the aegis of the IAU Working Group on Near-Earth Objects (WGNEO)
whereby researchers will be encouraged to meet their professional
obligation by obtaining a rapid peer review of any prediction they may make
of a possible impact by a sizable NEO, prior to public announcement.

The issues and guidelines outlined in Appendix A should form a basis for
consideration by the IAU WGNEO subject to consideration of the following

The general procedures and guidelines (Appendix A) should be reviewed at
the next IAU General Assembly in 2000 August.

The suggested time period required for the WGNEO review committee to
complete their analyses and report to the WGNEO chair needs to be defined
(i.e., this time period is currently given as 72 hours in Appendix A).

The recommendation is made that the NEO community of researchers adopt the
use of the "Torino Scale" as a common communication tool for describing the
hazards posed by NEOs.  The Torino Scale has been released to the public
and a description can be found at the following URL
( (also see article by Binzel below)

Planning and coordination for impact hazard mitigation should be conducted
in large part to minimize the adverse social consequences of impact

Procedures should be developed for the rapid characterization of
Tunguska-like detonation events which are likely to occur without warning.



The following guidelines for voluntary IAU review of reports of possible
future NEO impacts that exceed the Torino Scale level 1 has been discussed
among the Organizing Committee of the Working Group on NEOs. These
guidelines have been submitted to the IAU Executive Committee for their

Proposed IAU procedural guidelines in the event that a potentially Earth
threatening object is discovered.

The IAU Working Group on Near-Earth Objects (David Morrison, Chair)


-  that the International Astronomical Union (IAU) has charged its Working
Group on Near-Earth Objects (WGNEO), in consultation with astronomers
worldwide, to draft a set of recommended procedures to be followed in case
asteroids or comets are discovered that lead to predictions of potential
impacts on Earth;

-  that the recent cases of asteroids 1997 XF11 and 1999 AN10 have
provided, at an early stage after their discovery, real examples of such

-  that NEO scientists have a professional obligation to seek peer review
of their results before any public announcement of impact risk or threat;

-  that there is a need to identify the successive steps to be adopted by
the astronomical community in order to provide the authorities, the media
and the public with reliable information on the discovery of potentially
threatening objects;

RECOMMENDS the following procedures to be available to the members of the
astronomical community in any future case of discovery and/or theoretical
analysis leading to the prediction of impacts that fall at level 1 or
higher on the Torino Impact Hazard Scale at any apparition in the next

The IAU establishes the following review procedure available on a voluntary
basic to all scientists involved in any prediction of possible NEO impacts.
The information leading to such a prediction, consisting of an evaluation
of the case and all data and computational details necessary to understand
and reproduce the studies carried out by the authors, shall be transmitted
for confidential review to the chair of the WGNEO, the General Secretary of
the IAU, and the members of the WGNEO Review Team, before any announcement
and/or written document on the subject be made public on any information
media, including the World Wide Web. The membership of the standing Review
Team will be selected by the Chair of the WGNEO with the concurrence of the
IAU Division 3 President and the General Secretary, with names and e-mail
addresses posted on the IAU NEO webpage. The individual members of the NEO
Review Committee members shall review the work for technical accuracy and
shall communicate within 72 hours the results of their reviews to the chair
of the WGNEO and directly to the authors of the report or manuscript.

If the consensus of the above review supports the conclusion that there is
a significant impact risk, the results of this analysis will be posted on
the IAU webpage for public access. If the review disagrees with the
original analysis or if there is not a consensus among the reviewers, the
confidential results of the review will be given to the authors so they can
revise or improve their work, as they see fit. The news posted on the WGNEO
webpage shall represent the official position of the IAU; no further
information will be provided by the WGNEO, unless important updates become

The authors of the work are encouraged to refer the media to this IAU
position if they choose to make a public release of their conclusions. If
so requested by various agencies (e.g., NASA or ESA), the IAU will also
inform the responsible officials of these agencies of the results of the
WGNEO review.


by Richard Binzel, MIT

What is it for?

The Torino Scale is a "Richter Scale" for categorizing the Earth impact
hazard associated with newly discovered asteroids and comets.  It is
intended to serve as a communication tool for astronomers and the public to
assess the seriousness of predictions of close encounters by asteroids and
comets during the 21st century.

Why is the Torino Scale needed?

When a new asteroid or comet is discovered, predictions for where the
object will be months or decades in the future are naturally uncertain.
These uncertainties arise because the discovery observations typically
involve measurements over only a short orbital track and because all
measurements have some limit in their precision.

Fortunately, for the majority of objects, even the initial calculations are
sufficient to show that they will not make any close passes by the Earth
within the next century.  However, for some objects, 21st century close
approaches and possible collisions with the Earth cannot be completely
ruled out.

How does the Torino Scale Work?

The Torino Scale utilizes numbers that range from 0 to 10, where 0
indicates an object has a zero or negligibly small chance of collision with
the Earth.   (Zero is also used to categorize any object that is too small
to penetrate the Earth's atmosphere intact, in the event that a collision
does occur.)   A 10 indicates that a collision is certain, and the
impacting object is so large that it is capable of precipitating a global
climatic disaster.

The Torino Scale is color coded from white to yellow to orange to red.
Each color code has an overall meaning:


0.  The likelihood of a collision is zero, or well below
    the chance that a random object of the same size
    will strike the Earth within the next few decades.
    This designation also applies to any small object
    that, in the event of a collision, is unlikely
    to reach the Earth's surface intact.


1.  The chance of collision is extremely unlikely, about
    the same as a random object of the same size
    striking the Earth within the next few decades.


2. A somewhat close, but not unusual encounter.
   Collision is very unlikely.

3. A close encounter, with 1% or greater chance of a
   collision capable of causing localized destruction.

4. A close encounter, with 1% or greater chance of a
   collision capable of causing regional devastation.


5. A close encounter, with a significant threat of a
   collision capable of causing regional devastation.

6. A close encounter, with a significant threat of a
   collision capable of causing a global catastrophe.

7. A close encounter, with an extremely significant threat
   of a collision capable of causing a global catastrophe.


8. A collision capable of causing localized destruction.
   Such events occur somewhere on Earth between
   once per 50 years and once per 1000 years.

9. A collision capable of causing regional devastation.
   Such events occur between once per 1000 years
   and once per 100,000 years.

10. A collision capable of causing a global climatic
    catastrophe.  Such events occur once per
    100,000 years, or less often.


How does an object get its Torino Scale number?

An object is assigned a 0 to 10 value on the Torino Scale based on its
collision probability and its kinetic energy (proportional to its mass
times the square of its encounter velocity).  Categorization on the Torino
Scale is based on the placement of a close approach event within a
graphical representation of kinetic energy and collision probability
<link>.  An object that is capable of making multiple close approaches to
the Earth will have a separate Torino Scale value associated with each
approach.  (An object may be summarized by the single highest value that it
attains on the Torino Scale.)   There are no fractional values or decimal
values used in the Torino Scale.

Can the Torino Scale value for an object change?

Yes!  It is important to note that the Torino Scale value for any object
initially categorized as 1 or greater _will_ change with time.  The change
will result from improved measurements of the object's orbit showing, most
likely in all cases, that the object will indeed miss the Earth.  Thus, the
most likely outcome for a newly discovered object is that it will
ultimately be re-assigned to category 0.    Any object initially placed in
category 0 is unlikely to have its Torino Scale value change with time.

How did the Torino Scale get its name?

The Torino Scale was created by Professor Richard P. Binzel in the
Department of Earth, Atmospheric, and Planetary Sciences, at the
Massachusetts Institute of Technology (MIT).  The first version, called "A
Near-Earth Object Hazard Index", was presented at a United Nations
conference in 1995 and was published by Binzel in the subsequent conference
proceedings (Annals of the New York Academy of Sciences, volume 822, 1997.)

A revised version of the "Hazard Index" was presented at a June 1999
international conference on near-Earth objects held in Torino (Turin)
Italy.  The conference participants voted to adopt the revised version,
where the bestowed name "Torino Scale" recognizes the spirit of
international cooperation displayed at that conference toward research
efforts to understand the hazards posed by near-Earth objects.  ("Torino
Scale" is the proper usage, not "Turin Scale.)


From Brian G. Marsden < >
and Gareth V. Williams < >

The Torino workshop was about NEOs. Fewer than 0.1 percent of the
objects handled by the Minor Planet Center are NEOs. It was therefore
quite inappropriate for individual participants of the workshop even to
propose a recommendation on how it believes the MPC should operate with
regard to the totality of its work.

Authors of books and scientific papers make mistakes. This is not a
criticism of authors but a fact of life. Publishers of books and
editors of scientific journals have developed procedures--often a form
of peer review--to try and keep these authors' mistakes to a minimum.
Although such peer review by no means guarantees that incorrect
material is never published, there is a rather widespread opinion,
particularly in the astronomical community--and notably, it has seemed,
in an NEO community worried that the public could get the wrong idea
about an NEO that might pass the earth's doorstep--that this review is
somehow a "good thing".

Observers, specifically astrometric observers of minor planets, also
make mistakes. Again, this is not a criticism of observers but a fact
of life. Over the years the MPC has developed procedures to try and
keep these observers' mistakes to a minimum. Many of the 100 to 150
professional and amateur astronomers around the world who regularly
submit their astrometric observations to the MPC each month are aware
of this, and most of them actually seem to appreciate the efforts to
which the MPC goes to try and save them from the embarrassment of
having to correct or withdraw erroneous data. For many professionals
the analogy with writing a paper is complete, for the information
published in the Minor Planet Circulars and the actual observations in
the Supplement series are effectively the published paper in a
well-refereed journal. It should be borne in mind, too, that the MPC is
a service of the International Astronomical Union, and it is surely 
therefore appropriate that we publish data according to scientific
standards of which the IAU can be proud.

But the review process can take time, and it is quite ridiculous to
expect that this can always be done within minutes of submission. 
Complete checking, notably for a numbered minor planet, is often indeed
done within minutes, but it still requires human action to point out to
the observer that the specified UT time of observation was off by
exactly two hours. And to have a human working at the MPC at all times
would require a staff of at least five people--when at present we
manage with one-and-a-half.

The checking process for unnumbered and unidentified minor planets (and
incorrectly identified minor planets!), and the resulting
acknowledgment and transmission of identifications and designations to
the observer generally takes a little longer. Sometimes the small MPC
staff is in fact occupied with more urgent matters (like attending to
NEOs!), and the delay can amount to several hours. Sometimes, too, we
indeed wonder why we bother to work weekdays, evenings and weekends
when the "thanks" we receive are complaints that we should be working
the early-morning shift too...

New discoveries are credited and given provisional designations when
observations have been made on two nights. Since two nights are
generally necessary and frequently sufficient to establish an
identification at different oppositions, this is not an unreasonable
practice. "One-night stands" do not have tremendous value, and it is
sufficient that they be filed and routinely monitored from time to time
for linkages. As soon as the observations are received, for example,
they are examined for identifications with numbered and other
multiple-opposition objects, as well as recent discoveries. Otherwise,
random single-night detections really cannot be checked, and to publish
this enormous amount of material (almost exclusively of main-belt
objects reported by the large NEO surveys) actually therefore
diminishes the value of the collected file of observations as a source
of reliable data.

Sure, a program such as LINEAR reobserves the same part of the sky on
nearby nights, and linkages are possible. The Minor Planet Center does
in fact carry out such work (also making linkages for and with other
survey programs), on a routine basis when the survey observations are
reported immediately. But extensive examination of the single-night
detections is deliberately not made a high-priority effort.  For one
thing, the effort expended is really not commensurate with the slow
accumulation of useful results. For another, by not doing this we offer
to other astronomers, frequently amateurs involved in follow-up
activities, the possibility of being credited with their own
discoveries, when they can observe objects on two nights. If, then,
LINEAR detections can be recognized, there may immediately be an orbit
solution from four nights. Sometimes, too, the night-to-night linkages
by the observers are incorrect, but it may be several days before this
is clear.  This is yet another reason why it may be inappropriate to
publish observations quickly.

At the present time, the Minor Planet Circulars are being published in
monthly batches.  As we bring new computers properly on line, we expect
further automation, and we should be able to publish them more
frequently, perhaps several times a month..  In the mean time, we do
note that all the computed orbits appear on the nightly Minor Planet
Electronic Circulars, in order that observers--our most important
clientele--have access to the latest orbits and ephemerides.  There is
an important difference between publishing orbits and publishing
observations. Orbits are expected to change, with later results
replacing those earlier, and even when a bad orbit occasionally
appears, it is generally replaced the next night. Observations,
on the other hand, maintain their credibility--and minimize
confusion--by remaining inviolate. 

We maintain facilities for doing ephemeris computations, even for the
two-night detections, in our pages in the World Wide Web. For those
observers who wish to compute their own ephemerides, we provide
complete sets of orbital elements. Observers really do not need to have
access to the latest observations by other observers.  If services are
required beyond those we are providing (or plan to provide), they would
have to be paid for, but one should seriously consider whether funding
a five-person team at the MPC would be money well spent.  As the two
people most familiar with the subject, we are not at all convinced that
it would be.

As already stated, the Torino workshop was on NEOs. Despite the sudden
fivefold increase in their numbers caused by LINEAR last year (and
further increases anticipated for several NEO programs shortly), we are
coping with these objects quite satisfactorily, largely by means of The
NEO Confirmation Page and the MPECs.  NEO candidates are placed in the
NEOCP, in terms of ephemerides initially usually from single-night
detections, and they stay there--with updates--until we find it
appropriate (a) to accept an object as a genuine NEO, give it a
designation and publish the observations and orbital data on an MPEC,
(b) to appreciate that the object is a rather ordinary object, (c) to
declare that the object does not exist, or (d) to announce that the
object is in fact a comet and issue an IAU Circular and/or an MPEC. 
Possibility (a) is followed up by the automatic publication of further
observations on the nightly MPECs.  Possibility (b) results in treating
the object in the same way as other main-belt discoveries. Possibility
(c), while a little embarrassing to the reporting program, has no
permanent effect in that it does not compromise either IAU standards or
the MPC's files, because neither the observations nor an orbit has been
published. Possibility (d) has been happening with increasing frequency
and again impinges on the matter of discovery credit, particularly
because comets are named for their discoverers, some of whom might
thereby be eligible for a financial reward. Since the Smithsonian
Astrophysical Observatory has the responsibility for administering The
Edgar Wilson Award for amateur discoveries of comets, it is surely in
everyone's best interests to ensure that possibility (d) is handled
discreetly--again something that would not be possible if all
observations received by the MPC were immediately disseminated to

On some days the MPC handles 10,000 observations and computes 1000
orbits. Yes, it would be useful to have an additional staff member,
particularly when one bears in mind that two of the combined three
staff members of the MPC and the Central Bureau for Astronomical
Telegrams were recently away for ten days in Europe for the eclipse and
a meeting--so that the remaining MPC member also had to attend to the
production of the IAU Circulars.  We welcome constructive advice and
suggestions. But we object to the dissemination of ill-considered and
uninformed statements presented at meetings on somewhat unrelated
topics--particularly when such a statement, though passed off as a
recommendation of the meeting, was not in fact adopted by the
participants in the meeting.

From Kieffer-Olsen Jens < >
Dear Dr. Peiser,
It's difficult not to share your concern with respect to the Torino/Binzel
scale. While not questioning its scientific value, it seems lacking in
popular appeal on two counts.
First, it's dealing with probabilities rather than with facts like the
Richter and Fujita scales. To the public a category 2 or higher event,
which is later downgraded to 0, will inevitably be labelled a false
alarm - and perhaps even create a sense of frustration in some camps.
And secondly, it's two-dimensional, attempting to account for
probability of impact as well as severity of impact. I would have
thought it a better scale if it were three-dimensional, accounting for
lead time as well. It surely makes a difference to the layman as well
as a politician whether an impact is due 50 years hence or next year.
The perfect scale should reflect the urgency of budgetary action. A
category 1 event for example should require no more than careful
observation within existing budgets, whereas a category 2 event should
imply a requirement either to launch an interplanetary probe to examine
the object and its orbit, or preliminary planning to intercept it
within a relatively short time frame. Higher categories should directly
reflect an assessment of how massive the need for immediate allocation
of dedicated funds.
As it is, the new scale leaves it to scientists to convince politicians
of the need for action and funding each time a new alert is raised. 
For each 'false alarm' the likelihood of an alert being dismissed as a
case of 'crying wolf' increases.
Another aspect not touched by the scale is the evaluation of whether a
close encounter provides an opportunity for the object to be trapped in
Earth orbit. To the politician the challenge of providing funds for
such an exercise could be just as interesting - and far more rewarding.
We shouldn't speculate primarily in catastrophes, since fortunately
there are many, many more benign encounters. Once we have dealt
successfully (or even unsuccessfully ) with a number of those, we can
be expected to handle a malignant encounter as a matter of routine.
Yours sincerely
Jens Kieffer-Olsen, M.Sc.(Elec.Eng.)
Slagelse, Denmark

The CCNet is a scholarly electronic network. To subscribe/unsubscribe,
please contact the moderator Benny J Peiser < >.
Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at

CCCMENU CCC for 1999