PLEASE NOTE:
*
CCNet, 55/2000 - 8 May 2000
----------------------------
POEM OF THE DAY
Asteroid 'Kleopatra' from Arecibo
Its dogbone shape has made us laugh
today
and some of us may be suspicious - was
the image
'tweaked' a bit by someone with a sense
of humour?
The Iron Age has ended long ago, and
'rustbelt' industry
on Earth is winding down, yet settlement
in space
might need strong structures, and
lifting them from here
would be extravagant. Now there we
see a place
with ample iron and nickel for
construction.
One day we'll mine this metal bone,
smelt iron on the spot
if energy's available, and if not, ship
it slow and cheaply
to a place where space age smiths can
fabricate
the ploughshares needed for our New
Worlds' farms
or build great ships for our new
age of exploration.
Malcolm Miller
(c)
5.5.2000
stellar2@actonline.com.au
(1) SPACEGUARD UK - IMPACT TEN
Jonathan Tate <fr77@dial.pipex.com>
(2) DUST GRAINS OLDER THAN COMETS
ASTRONOMY NOW, 8 May 2000
(3) ASTRONOMERS CATCH IMAGES OF GIANT METAL DOG BONE ASTEROID
NASANews@hq.nasa.gov
(4) SIDING SPRING CORRECTION
Reiner M. Stoss <RSTOSS@HRZ1.HRZ.TU-Darmstadt.De>
(5) SPACEGUARD CANADA OVERSIGHT
Michael Paine <mpaine@tpgi.com.au>
(6) MORE SCALES, OR WHY I WILL NEVER USE THE TORINO SCALE
Alain Maury <alain.maury@obs-azur.fr>
(7) AND FINALLY: DON'T BLAME THE SUN, RESEARCHERS CLAIM
Andrew Yee <ayee@nova.astro.utoronto.ca>
==================
(1) SPACEGUARD UK - IMPACT TEN
From Jonathan Tate <fr77@dial.pipex.com>
INTRODUCTION TO IMPACT 10
Welcome to the 10th edition of "Impact". When Impact 1
was published,
who would have believed that we would be where we are today by
Issue
10! The government Task Force is forging ahead, having recently
returned from their fact-finding trip to the United States.
Reports from all sides of the discussions have been very
positive, and
it appears that the Task Force is committed to producing a
meaningful
and robust report to the minister in June. Apart from the Task
Force,
other activities have included a busy lecture schedule that
included a
presentation to the annual conference of the Institute of
Emergency
Management in March. It was interesting to interact with those
who plan
for and deal with natural disasters, and to find out what sort of
information, warning and advice that they require to deal with
catastrophic events. It would be true to say that the emergency
services
are almost totally unaware of the nature and scale of the hazard
from
cometary or asteroidal impacts, so events such as this are vital
for
spreading the word.
The level of exposure in the media has been surprisingly high
recently,
given that there has been no "Earth shattering" news.
Astronomy Now
magazine published two related articles in their March edition in
a
Focus section devoted to the impact hazard. Also in March there
were two
television programmes, typically on the same evening, one dealing
with
the search for a large iron meteorite in the Sahara desert, and
the
other with the impact hazard in general. The latter, while being
generally accurate, did give the impression that
astronomers have the
NEO situation under control - a fact that is sadly erroneous.
Of course, all eyes are now on the progress of the NEAR
spacecraft,
recently re-named "NEAR-Shoemaker" in honour of Gene
Shoemaker, the
pioneer of impact studies, and inspiration for Spaceguard
organisations
around the world. The stunning images of Eros are breathtaking,
and
excellent science is already being done. Well done NASA, at least
this
one worked!
The next issue of "Impact" will be due in July when I
hope to be able
to brief you all on aspects of the Task Force report. Of course,
there
is no reason why I should be party to this document, but I am
hoping to
have at least some information by then. In the meantime, we will
continue to support the task Force in their work, reinforce our
links
with Spaceguard organisations elsewhere, and "keep watching
the skies".
Jay Tate
Figheldean
April 2000
-------------
FINAL SUBMISSION BY SPACEGUARD UK TO THE NEO TASK FORCE
ASSUMPTIONS
· The Task Force accepts the numerous threat assessments
produced in the
last decade; that the threat from asteroidal or cometary
impacts,
while being low probability but very high consequence,
substantially
exceeds the government's own threshold of risk
tolerability.
· At the policy and co-ordination level any Spaceguard programme
must be
international in nature.
· Cost will preclude an immediate "Rolls-Royce"
solution, but sensible
investment will be commensurate with the hazard.
WHY? - THE REQUIREMENT
The requirement for some sort of national Spaceguard centre is
predicated on the following factors:
· The international scientific community (represented by,
amongst
others, the UN and IAU) strongly supports the
establishment of
national Spaceguard Centres.
· The detection of asteroids and comets is only the beginning of
a long
and complicated process to determine their orbits and
their physical
properties. The follow-up work required for this is not as
glamorous
as detection, but is just as essential. The UK has
established
expertise in the fields required for this work.
· Without a national focus, the UK will be totally dependent on
foreign
agencies for its information. As we saw in March 1998 when
it was
announced that an asteroid (1997 XF11) had the potential
to strike
the Earth, there was no response from the British
government at all.
The public, looking for reassurance and information, was
left in the
lurch. Private and foreign organisations filled the gap
and assumed
responsibility for telling the public what was going on.
There have
been three more cases recently of asteroids with small but
non-zero
collision probabilities and again there has been no
response from
government departments. As the detection programmes in the
US ramp
up, cases like these will happen more and more frequently.
A
dedicated organisation is required to handle this
situation.
· NEO issues are complex, and require specialist handling/
specialist
centre.
· The National Spaceguard Centre proposed by Spaceguard UK would
be that
focus, would undertake vital and complex research and
could be
established for £65,000, and run for £600,000 per year
(i.e. it could
operate for over fifty years for the price of one Tornado
aircraft).
WHAT? - OPTIONS OPEN TO HER MAJESTY'S GOVERNMENT
· Do nothing - contrary to common sense and public opinion.
· Establish a National Spaceguard Centre as proposed below - a
modest
but evolutionary approach.
· Enter negotiations with European or other bodies - possibly
the
nightmare scenario (all talk, no action).
· Recommend an accelerated programme, based on the three-phase
proposal
below - the "big bang" option.
· Something else.
HOW? - RECOMMENDATION
It is suggested, in line with the recommendations of the IAU and
the UN,
that a National Spaceguard Centre be established, in three
phases, with
the following Mission Statement:
· To provide an expert domestic advisory service to the public,
government, media and relevant authorities regarding the
environmental hazard posed by natural extraterrestrial
objects.
· To facilitate UK involvement in the international Spaceguard
programme.
· To conduct world-leading research regarding the nature and
extent of
this hazard.
Phase 1
Establish National Spaceguard Centre. The most cost-effective
option is
to establish a central headquarters, with outstations optimally
located
to achieve their missions. The following are proposed:
· Armagh Observatory - The primary location, with the following
responsibilities:
- Theoretical analysis of NEO astrometry, extrapolation of
orbits,
identification of priority follow-up
observations, in collaboration with other UK and overseas
dynamicists.
- Co-ordination of follow-up astrometry by other observers, both
UK and
others.
- Research into other effects of NEOs upon the terrestrial
environment
(atmospheric dusting, etc.).
- Modelling of atmospheric interactions by small (50-100 metre)
impactors.
- Involvement in NEO space missions.
- Collaboration with NEO search programmes elsewhere.
- Investigations of feasible UK search programmes, e.g. using
VISTA
data.
- Investigations of the feasibility of a dedicated UK NEO search
system.
- Investigations of outer solar system objects: theory and
detection
systems for bodies such as long-period
comets, Halley-type comets (dark and active), Centaurs
etc.
- Co-ordination of Public Understanding of Science and Technology
(PUST)
programmes.
· Queen's University, Belfast - Lead centre for physical
observations of
NEOs.
· In or near Edinburgh (ROE, University of Edinburgh or St
Andrews) -
To carry out the following responsibilities:
- Close collaboration with all aspects of the work at the main
centre in
Armagh.
- Rapid access to the UKST plate library at ROE to make possible
precoveries of NEOs discovered elsewhere.
- Lead centre for investigations of new NEO search programmes
using
VISTA data or other telescopic systems
already in operation, and the design of novel NEO search
systems.
- Collaborate with research staff at the Astronomy Technology
Centre at
Edinburgh.
· Near London - One public liaison / PUST manager employed to
promote
the activities of the National Spaceguard Centre and
astronomy in
general through media contacts, public presentations etc.
as well as
being a link with external bodies such as disaster
management
agencies, industry and others.
· Total annual budget for the proposed national Spaceguard
Centre -
£600,000
Phase 2
Construction and operation of a 2m-class follow-up telescope
(possibly
robotic), either as a national project or in collaboration with
other
nations. Details and costings will be produced by the National
Spaceguard Centre.
Phase 3
Construction and operation of 4m-class detection telescope,
either as a
national project or in collaboration with other nations. Details
and
costings will be produced by the National Spaceguard Centre.
CONCLUSION
It is now clear that cosmic impacts have played an important role
in
the geological and environmental development of the Earth, and
may even
have been the dominant factor in the evolution of life. The
universe in
which we live is a violent and unpredictable place, and this
realisation is driving a paradigm shift in scientific thinking
analogous with that caused by the work of Sir Isaac Newton and
the
publication of Darwin's "On the Origin of Species by Means
of Natural
Selection". The impact threat can be summarised as follows:
· Rare. Major impacts are rare, therefore easy to dismiss as
irrelevant
to the current generation. Indeed, the whole subject has
suffered
from a substantial "giggle factor", though this
is waning fast.
· Devastating. Unlike other natural catastrophes there is no
upper
limit to the potential energy release into the ecosystem.
Physical
effects from the impact aside, even small impacts can have
far
reaching climatic effects and human institutions, which
are far from
robust in the face of disaster, are especially vulnerable
in our
global civilisation.
· Avoidable. It is now technically possible to avoid or, at
least
mitigate the effects of impacts. Impacts have
catastrophically
disrupted the ecosphere in the past, and
will again; the only question is when. But, for the first
time in the
history of our planet, there is a species with the ability
to prevent
cataclysm. We owe it to the future of mankind and all
other forms of
life that share our home to start the project that will
prevent
widespread destruction in the future.
-------------
THE SPACE DEVELOPMENT COUNCIL
Introduction
On 8th April 2000, at the offices of KPMG in London, an
extraordinary
meeting took place, bringing together many of the major amateur
organisations concerned with the development of space. The
meeting was
organised by the Mars Society of UK.
Membership
The following were represented:
· ASTRA
· Space Age Associates
· Space Settlers
· Spaceguard UK
· Mars Society
· Discovery Space Club
· British Rocketry Oral History Programme
The British Interplanetary Society and UKSEDS were also
represented, but
only as observers, in line with their charitable status that
precludes
them from active political lobbying.
Mission Statement
The delegates unanimously agreed a mission statement for the
Space
development Council as follows:
"To provide mutual support and co-ordination between
organisations
involved with the exploration and development of the space
environment."
A constitution is under development, and a trawl for other
organisations
that may wish to become involved is underway. Already there are a
number who have stated a desire to join the Council, boosting the
membership further.
Structure
Andrew Nimmo was elected Chairman of the council, and each
organisation
represented has a member. A secretary, Captain John Broomfield,
was
elected, and a treasurer will be elected soon.
Narrative
Some readers might be tempted to criticise this initiative as
another
example of amateur meddling in the realm of professionals, but it
is
worth pointing out that the combined membership of the
organisations
represented exceeds 4000. There are also a number of additional
organisations that are willing to join. Add this to the
substantial
international membership of organisations such as the Planetary
Society
and the various Spaceguard organisations around the world, and it
becomes obvious that the SDC will be a very significant lobby
base for
UK participation in the development of space based activities.
The Future
The Space Development Council will now enter a phase of
consolidation
and organisation before starting work on its primary task. The
concept
of the SDC as a facilitator for co-operation and co-ordination is
simple, sensible and exciting. If all goes well this could become
a
significant force in UK space development.
Spaceguard UK Perspective
At the beginning of the planning process for the SDC I raised
some
concerns about Spaceguard UK's place in this organisation. In
particular
I was concerned that Spaceguard UK, as a single-issue
organisation,
would be out of place and uncomfortable lobbying for things like
ISS and
trips to Mars. I pointed out to the group that we are not a
"blue sky"
organisation, but that we have our feet firmly planted in
reality, with
solid, costed proposals that have reached the highest levels of
government. In addition, we have the almost unanimous support of
the
relevant experts in the scientific community and significant
international backing. However, the fact remains that we are, at
present, a lay group with an interest in the space environment.
Having
debated the point with a number of people I decided that there is
a
place for us on the SDC and have acted accordingly. As it
happens,
Spaceguard is now one of the SDC priorities, so we have an added
resource to call upon should it become necessary!
===========
(2) DUST GRAINS OLDER THAN COMETS
From ASTRONOMY NOW, 8 May 2000
http://spaceflightnow.com/news/n0005/08comets/
Dust grains older than comets
BY NEIL ENGLISH
Comet Hale-Bopp. Photo: Courtesy NASA/JPL
Comets, the icy wanderers that occasionally grace the inner Solar
System, have long been considered the oldest and most
pristine
components of the primordial material out of which the planets
and their
cortege of satellites were spawned. Now, new research has cast
fresh
doubts on this long-cherished impression. In a paper published in
the
April 27 edition of Nature, the American planetary scientist
Scott
Messenger, at Washington University, has unearthed new and
provocative
evidence suggesting that a class of interplanetary dust grains
(IDPs)
might well have pre-dated the planetary system.
IDPs are a diverse assemblage of dusty material, with typical
sizes
between 0.1 and 1.0 microns (a micron is one millionth of a
metre), that
have retained much of their volatile inventory in the form of
water ice
and other ices. And while this material continually rains down on
the
earth, it is only in the upper atmosphere, particularly in the
stratosphere, that unaltered IDPs are routinely retrieved.
Messenger chemically analysed a variety of IDP specimens,
including
isolated dust grains and cluster IDPs, comprising of many,
loosely-bound
grains. After analysing 40 individual IDPs and 28 cluster IDPs,
Messenger showed that the latter were considerably more enriched
in
deuterium - a 'heavy' species of atomic hydrogen, containing an
extra
neutron in its atomic nucleus - relative to isolated individual
IDPs.
Deuterium is a sensitive indicator of the physical environment in
which
the grains formed. In particular, because its formation and
concentration inside dust grains is favoured in very cold
environs,
deuterium tends to become enriched in the coldest parts of space,
particularly cool molecular clouds - the cocoons out of which new
stars
emerge - where temperatures can be as low as 10 K.
But the biggest surprise came when Messenger compared the
relative
abundance of deuterium in comets, primitive meteorites and
cluster IDPs
studied to date. Though IDPs exhibited a larger overall range in
deuterium enrichments, they were often up to ten times more
enriched in
deuterium relative to cometary material. Indeed, the enrichments
are
consistent with the idea that cluster IDPs may have pre-dated the
Solar
System and may even have been derived from a variety of cool
molecular
clouds that brushed by this neck of the Galaxy before the Sun was
even a
distant idea.
More work will undoubtedly serve to establish the precise age of
these
tiny and ancient interstellar caravels.
Copyright 2000, Astronomy Now
==================
(3) ASTRONOMERS CATCH IMAGES OF GIANT METAL DOG BONE ASTEROID
From NASANews@hq.nasa.gov
Donald Savage
Headquarters, Washington,
DC
May 4, 2000
(Phone: 202/358-1547)
Jane Platt
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-0880)
RELEASE: 00-74
ASTRONOMERS CATCH IMAGES OF GIANT METAL DOG BONE ASTEROID
NASA astronomers have collected the
first-ever radar images
of a "main belt" asteroid, a metallic, dog bone-shaped
rock the
size of New Jersey, an apparent leftover from an ancient, violent
cosmic collision.
The asteroid, named 216 Kleopatra, is a
large object in the
main asteroid belt between Mars and Jupiter; it measures about
135
miles (217 kilometers) long and about 58 miles (94 kilometers)
wide. Kleopatra was discovered in 1880, but until now, its
shape
was unknown.
"With its dog bone shape, Kleopatra
is one of the most
unusual asteroids we've seen in the Solar System," said Dr.
Steven
Ostro of NASA's Jet Propulsion Laboratory, Pasadena, CA, who led
a
team of astronomers observing Kleopatra with the 1,000-foot (305-
meter) telescope of the Arecibo Observatory in Puerto Rico.
"Kleopatra could be the remnant of an incredibly violent
collision
between two asteroids that did not completely shatter and
disperse
all the fragments."
The astronomers used the telescope to
bounce radar signals
off Kleopatra. With sophisticated computer-analysis
techniques,
they decoded the echoes, transformed them into images, and
assembled a computer model of the asteroid's shape. The
Arecibo
telescope underwent major upgrades in the 1990s, which
dramatically improved its sensitivity and made it feasible to
image more distant objects.
These new radar images were obtained
when Kleopatra was about
106 million miles (171 million kilometers) from Earth.
Travelling
at the speed of light, the transmitted signal took about 19
minutes to make the round trip to Kleopatra and back.
"Getting images of Kleopatra from
Arecibo was like using a
Los Angeles telescope the size of the human eye's lens to image a
car in New York," Ostro said.
Kleopatra is one of several dozen
asteroids whose coloring
suggests they contain metal. Kleopatra's strong reflection
of
radar signals indicates it is mostly metal, possibly a
nickel-iron
alloy. These objects were once heated, melted and
differentiated
into structures containing a core, mantle and crust, much as the
Earth was formed. Unlike Earth, those asteroids cooled and
solidified throughout, and many underwent massive collisions that
exposed their metallic cores. In some cases, those
collisions
launched fragments that eventually collided with Earth, becoming
iron meteorites like the one that created Meteor Crater in
Arizona.
"But we don't need to worry about
Kleopatra -- it will never
hit Earth," Ostro said.
"The radar-based
reconstruction of Kleopatra's shape shows
the object's two lobes connected by a handle, forming a shape
that
resembles a distorted dumbbell, or dog bone," said Dr. R.
Scott
Hudson of Washington State University, Pullman, WA.
"The shape
may have been produced by the collision of two objects that had
previously been thoroughly fractured and ground into piles of
loosely consolidated rubble. Or, Kleopatra may once have
been two
separate lobes in orbit around each other with empty space
between
them, with subsequent impacts filling in the area between the
lobes with debris."
"The radar observations indicated
the surface of Kleopatra is
porous and loosely consolidated, much like surface of the Moon,
although the composition is different," said Dr. Michael
Nolan of
the Arecibo Observatory. "Kleopatra's interior
arrangement of
solid metal fragments and loose metallic rubble, and the geometry
of fractures within any solid components, are unknown. What is
clear is that this object's collision history is extremely
unusual."
"It is amazing that nature has
produced a giant metallic
object with such a peculiar shape," said Ostro.
"We can think of
some possible scenarios, but at this point none is very
satisfying. The object's existence is a perplexing mystery
that
tells us how far we have to go to understand more about asteroid
shapes and collisions."
The team's findings will appear in the
May 5 issue of the
journal Science. Ostro's team includes Hudson; Nolan and
Jean-Luc
Margot of the Arecibo Observatory; Dr. Daniel Scheeres of the
University of Michigan, Ann Arbor; Dr. Donald Campbell of Cornell
University, Ithaca, N.Y; Dr. Christopher Magri of the University
of Maine at Farmington; and Jon Giorgini and Dr. Donald Yeomans
of
the Jet Propulsion Laboratory.
The Kleopatra images are available at:
http://www.jpl.nasa.gov/pictures/kleopatra
The Arecibo Observatory is part of the National Astronomy
and
Ionosphere Center, operated by Cornell University for the
National
Science Foundation. The Kleopatra radar observations were
supported by
NASA's Office of Space Science, Washington, DC. JPL is managed
for NASA
by the California Institute of Technology in Pasadena.
=============================
* LETTERS TO THE MODERATOR *
=============================
(4) SIDING SPRING CORRECTION
From Reiner M. Stoss <RSTOSS@HRZ1.HRZ.TU-Darmstadt.De>
Duncan Steel wrote:
"Number of NEAs discovered from Siding Spring since the end
of
1996 = ZERO"
This is not true. Rob McNaught/ M. Hartley discovered one in
1999 and one in 1997! Both have H brighter than 18.3mag and were
discovered at 413.
Not significant "but the story must be consistent
with reality" ;-)
See:
http://cfa-www.harvard.edu/iau/lists/YearlyBreakdown.html
http://cfa-www.harvard.edu/iau/lists/Amors.html
Discovery date, site and discoverer(s)
1999 RM28 1999 09 03 413 R.
H. McNaught
1997 WS22 1997 11 24 413 M.
Hartley
Cheers,
Reiner Stoss
611 Starkenburg
http://www.regio-info.de/sternwarte-heppenheim/
=================
(5) SPACEGUARD CANADA OVERSIGHT
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
Following the posting of my "Bigger telescopes" article
on CCNet,
Jeremy Tatum from Spaceguard Canada sent me an email pointing out
that
my list of major programs searching for NEOs left out the
Canadian
program that uses the 1.85m Plaskett telescope on Vancouver
Island.
See http://astrowww.phys.uvic.ca:80/~balam/
and
http://www.seameadow.com/aikman.html
Jeremy advises that the program has "the largest telescope
in the world
used in a regular programme of NEO follow-up astrometry... It is
recognized by those who observe (rather than write about) [point
taken!]
asteroids that discovery and follow-up are more efficient when
performed independently by programmes dedicated to each of these
ends.
Discovery cannot proceed efficiently when encumbered by the need
to do
follow-up astrometry, nor can follow-up be efficient if diverted
by
discovery. Discovery and follow-up teams are typically in routine
e-mail contact with each other, so that discovery of potentially
interesting NEOs is immediately transmitted to follow-up
teams."
He is quite correct in that my list is biased towards discovery
rather
than follow-up work and I apologise for the oversight. I did
stress
several times in the article (as did Don Yeomans) that follow-up
work is
vital to Spaceguard.
I don't have the experience to respond in detail to Duncan
Steel's
comments about the "Spaceguard Goal" - Duncan was
involved with the
various discussions in the early 90s - but from the published
reports I
thought the "goal" had started out as 80% of NEAs and
increased to 90%.
Trouble is it is not clear whose goal it was!
regards
Michael Paine
==============
(6) MORE SCALES, OR WHY I WILL NEVER USE THE TORINO SCALE
From Alain Maury <alain.maury@obs-azur.fr>
Over recent months, I have seen numerous critical remarks by
various
persons concerning the Torino scale, aka the Binzel scale.
- My own personal point of view as an observer, who has had in
the past
to answer questions from journalists, is that I will never use
Binzel's
scale. A scale is something that measures something. The
something we
are referring to in this case is a probability of something
happening
(or better: not happening) in the future.
Moreover, this something is going to fluctuate a lot, depending
on
observations in the past or in the future. Most likely, we will
have to
worry about more objects similar to the five that are currently
in the
NEODys page. Alan Harris of JPL, in a personal communication,
pointed out quite correctly that it may take a million objects
with an
impact probability of one millionth before we get one worth
worrying
about, i.e., and not surprisingly so, it is very unlikely that in
our
lifetimes we shall have anything other than objects having a
given
impact probability after the first observations, but which, with
a new
set of observations, shall turn into level 0 objects (I mean,
white on
the Binzel scale: harmless).
To be logical, the Scale would have to relate to the probability
of a
large explosion happening on the surface of the Earth caused by
the
impact of an asteroid. My guess is that the public is not
interested in
"probability" of large explosions occurring. What
it wants to know is
whether or not *this* object will hit the earth: yes or no, when
and do
we have time to do something about it.
While with insufficient astrometric observations the orbital
elements
are quite uncertain, leading to uncertain probabilities, even
lousier
photometric observations mean uncertain taxonomic determinations
that do
not allow more than a rough measure of the mass of the object and
estimates of the consequences of the impact. I mean, I would not
claim
such an object is harmless or not when I know perfectly well that
I have
no way of establishing its diameter and composition, other than
from a
rough single-color photometric observation. With the current
Binzel
scale, every person concerned knows that a metallic
"yellow 4" is a
stony "orange 7".
- A scale is something that is adopted and used by most
specialists in
the field. In this respect, I feel quite frustrated by the way
things
were handled in Torino. Subcommittees reflected on various
aspects of
the NEO problem. One subcommittee (composed, I assume, of people
having
some expertise) discussed the scale. The meeting ended before
clear
conclusions could be drawn, and we were told that small
committees
would draw up recommendations for us. Since I was neither in the
subgroup that discussed this scale, nor in the small committee
that
finished the work, I have to say that, despite all that has been
said,
here and there about this scale, and despite its endorsement by
the IAU,
I have yet to hear a convincing argument in favor of it, other
than
political.
- As far as I am concerned, I will use the Maury scale (MS for
short:-),
which is a simple binary scale (i.e. perfectly harmless and we
say so,
or not harmless at first sight and we take the time to explain
what we
know and what we don't), not approved by the IAU.
Most, if not all of the time, the first level of the MS is used,
and it
is a simple phrase that, I guess, will be more than enough to
answer the
questions of most journalists:
"We have here an object, discovered a few
weeks/months ago (name
the discoverer and the country in which the discovery was
made),
whose orbit was computed by several scientists working in
this field
(state names and institutions/countries), which shows a
possible
close approach to the Earth in (give the date) with a
probability of
impact of (give the probability). This means that there is
a
probability of (give one minus impact probability, usually
a number
like 99.9999%) that there will be no impact at that time.
Close
approaches of asteroids to the Earth, astronomically
speaking, are
not such rare events, but it is difficult, many years in
advance, to
make very precise estimations of impacts. So far, all
objects for
which such non-zero impact probabilities were computed,
and for which
new observations became available, were shown to be
completely
harmless. We know very little about this object, which is
probably
between (give a size estimate) and more observations are
needed".
I think journalists and the public will get this idea pretty
well, as
they have in the past, at least much better than an obscure
scale,
putting numbers, colors and subclasses where none is needed.
This is much longer than to say "this object is a yellow
3" and then
leave. But it is much shorter than to say the same, then have to
explain
it, trying --if possible-- during the conversation to explain
what the
above phrase says so concisely.
In the very extremely unlikely case that the first level MS would
not be
adequate (if we were unlucky enough to find an object really
worth
worrying about), I will have to improvise a second one that will
describe the situation as exactly as possible. We should say what
we
know and what we don't, at the moment of the interview,
explaining why
the situation might still change, in the most precise and honest
manner
possible. If such a case should occur, I think we will have much
more
time to talk to the press, and more time and ways to make fools
of
ourselves, unless of course the object is a "red 8"
coming in a few
hours, and the interview is held just at the wrong place at the
wrong
time, in which case, I recommend leaving the studio as soon as
possible.
Alain Maury
-----------------
MODERATOR'S NOTE: I should point out that, almost one year after
the
Torino IMPACT meeting, none of the recommendations made by the
delegates have been made available yet. I understand that there
are
ongoing attempts to change or overturn some of the decisions
taken in
Turin. Unless the IAU can clean up the Torino mess soon, these
shenanigans and delays do not bode well for the forthcoming IAU
General
Assembly in Manchester.
==================
(7) AND FINALLY: DON'T BLAME THE SUN, RESEARCHERS CLAIM
From Andrew Yee < ayee@nova.astro.utoronto.ca
>
New Scientist
http://www.newscientist.com
Contact: Claire Bowles, 0171 331 2751, claire.bowles@rbi.co.uk
Don't blame the Sun
GREENHOUSE effect sceptics may have lost their final excuse. The
Sun
has been dethroned as the dominant source of climate change,
leaving
the finger of blame pointing at humans.
A correlation between the sunspot cycle and temperatures in the
northern hemisphere seemed to account for most of the warming
seen up
until 1985. But new results reveal that for the past 15 years
something
other than the Sun -- probably greenhouse emissions -- has pushed
temperatures higher.
In 1991, Knud Lassen of the Danish Meteorological Institute in
Copenhagen and his colleague Eigil Friis-Christensen found a
strong
correlation between the length of the solar cycle and temperature
changes throughout the northern hemisphere. Initially, they used
sunspot and temperature measurements from 1861 to 1989, but later
found
that climate records dating back four centuries supported their
findings. The mysterious -- and unexplained -- relationship
appeared to
account for nearly 80 per cent of the measured temperature
changes over
this period.
Now Lassen and astrophysicist Peter Thejll have updated the
research
and found that while the solar cycle still accounts for about
half the
temperature rise since 1900, it fails to explain a rise of 0.4 C
since
1980. "The curves diverge after 1980," says Thejll,
"and it's a
startlingly large deviation. Something else is acting on the
climate."
Although they can't be sure, they suspect that emissions from the
burning of fossil fuels are responsible. "It has the
fingerprints of
the greenhouse effect," says Thejll. Other climatologists
agree. "It
sounds like an actual piece of evidence for greenhouse
warming," says
Richard Betts of Britain's Hadley Centre for Climate Prediction
and
Research in Bracknell, Berkshire. "Any natural effect would
swamp the
small early changes, so you'd expect to see the larger changes
more
recently.'
Others, however, remain sceptical about this line of research.
Tom
Wigley at the National Center for Atmospheric Research in
Boulder,
Colorado, who in 1992 criticised Lassen's initial research,
points out
that since then no one has provided a convincing physical
explanation
for the correlation between the sunspot cycle and temperature.
Wigley
accepts that solar effects may have dominated until about 1950,
but
certainly not as late as
1980.
Lassen and Thejll recognise that the link between the solar cycle
and
climate is controversial. But they hope their new findings will
move
climate-change researchers towards a more balanced view. "It
became
political," says Thejll. "We're now seeing that the Sun
plays a role,
and something in addition to the Sun. Maybe that will help people
see
there is room for both."
New Scientist issue: 6th MAY 2000
PLEASE MENTION NEW SCIENTIST AS THE SOURCE OF THIS STORY AND, IF
PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO:
http://www.newscientist.com
[NOTE: An illustration supporting this release is available at
http://www.newscientist.co.uk/news/news_223733.html
]
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