PLEASE NOTE:
*
CCNet, 95/2000 - 26 September 2000
----------------------------------
"One of the greatest science
fiction writers of all time
is backing Liverpool's bid to build an
early warning system
against asteroids threatening the earth.
Sir Arthur C Clarke,
creator of 2001: A Space Odyssey, has
written an open letter
to the people of Liverpool. In the
letter, the 82-year old
pledges his support for the city to play
a leading role in
tracking asteroids and comets on a
potential collision course
with earth."
-- Emma Gunsby, Daily Post,
26 September 2000
"Reading through the responses from
astronomers searching for
NEOs, their consensus seems to be that
there is now an excellent
chance that the recommended 3 meter
telescope will be funded by
the UK Government. My own past
experience has been in covering
space programs more generally, and what
I have watched for some
15 years now is many, many groups of
scientists and engineers
come up with projects which they thought
were great, necessary
to their countries' well being, and
certain to be funded. Most
of these projects are now little more
than a collections of
press releases, 4-color brochures, and
engineering studies.
I have several bookcases full of
them."
-- Ed
Grondine, 26 September 2000
(1) WHY I'M BACKING CITY'S BID TO PROTECT EARTH
LEGENDARY SCIENCE FICTION WRITER SUPPORTS
EARLY-WARNING TELESCOPE
Daily Post, 26 September 2000
(2) IS AUSTRALIA AWAKENING FROM NEO HIBERNATION?
Michael Paine <mpaine@tpgi.com.au>
(3) NOAH'S KITCHEN UTENSILS DISCOVERED?
National Geographic News, 25 September 2000
(4) THE EUROPEAN COMMSSION ON EARTH OBSERVATIONS FROM SPACE
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) ASTEROID 2000 DP107
Petr Pravec <ppravec@asu.cas.cz>
(6) NEO TASK FORCE REPORT: COULD THERE BE UNINTENDED
CONSEQUENCES?
Ed Grondine <epgrondine@hotmail.com>
(7) NOAH'S TAURID CONNECTION
Leroy Ellenberger <c.leroy@rocketmail.com>
(8) ON LUNIES, HERMIANS & OTHER MINI-PLANETS
Duncan A. Lunan <astra@dlunan.freeserve.co.uk>
==================
(1) WHY I'M BACKING CITY'S BID TO PROTECT EARTH
LEGENDARY SCIENCE FICTION WRITER SUPPORTS
EARLY-WARNING TELESCOPE
From Daily Post, 26 September 2000
http://liverpool.com/news/
By Emma Gunsby
ONE of the greatest science fiction writers of all time is
backing Liverpool's bid to build an early warning system
against asteroids threatening the earth.
Sir Arthur C Clarke, creator of 2001: A Space Odyssey, has
written an open letter to the people of Liverpool. In the
letter, the 82-year old pledges his support for the city
to play a leading role in tracking asteroids and comets on
a potential collision course with earth.
He writes: "The UK has a proud tradition of building fine
scientific instruments, especially astronomical telescopes,
and Liverpool has become a distinguished centre for this
high technology industry. I think that it would be most
fitting if the engineers and craftsmen of Merseyside built
the premiere British Spaceguard telescope, for the benefit
of the whole country. Such an undertaking will be a
significant technical challenge, but the result will
contribute substantially to the protection of our only home
- the Earth."
Sir Arthur also believes that Liverpool is a fitting place
for the telescope to be built because of its reputation as
a centre of excellence for interplanetary studies.
He writes: "There is another excellent reason why Liverpool
should be involved. It was there that Phillip Cleator
founded the British Interplanetary Society in 1933, and one
of the Society's earliest supporters was John Moores."
Last week, the Government task force on near-earth objects
recommended the building of a new super-telescope to watch
the skies for threats. The three-man team, set up by
Science Minister Lord Sainsbury, wants a three metre survey
telescope designed to spot much smaller objects than those
now detected by existing instruments.
And Sir Arthur has welcomed the recommendations made in the
report. He said: "The type of instrument recommended in the
report will be the most powerful surveillance telescope in
the world, and will be able to detect the sort of object
that wiped out an area the size of Greater London in 1908 -
luckily in Siberia."
Dr Benny Peiser, a member of Spaceguard UK, is thrilled by
the inspirational response. He believes John Moores
University stands a very good chance of being chosen
for this project.
He said: "This is a golden opportunity for Merseyside to
become the world's top producer of high-tech telescopes. It
would be a fitting contribution from our university, the
city of Liverpool and Britain as a whole to international
efforts to safeguard our world from dangerous asteroids and
comets."
Sir Arthur invented the idea of a Spaceguard system against
asteroids and comets. The name Spaceguard first appeared in
his 1973 novel Rendezvous with Rama. He added: "I am
delighted, therefore, that the name that I invented has
been adopted both by NASA and in the UK. The prospect of a
real Spaceguard project has come a step closer."
Many of Sir Arthur's visionary concepts have become
scientific fact.
Copyright 2000, Daily Post
=============
(2) IS AUSTRALIA AWAKENING FROM NEO HIBERNATION?
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny
The Age is a major newspaper in Australia. Strange headline
but the rest is good.
regards
Michael Paine
Asteroid busters urge Australia to help avert the killer blow
By RANDALL ASHBOURNE
ADELAIDE
Friday 22 September 2000
International pressure is mounting for Australia to
establish new long-range telescopes to track killer
asteroids that could devastate life on Earth.
Adelaide University vice-chancellor Mary O'Kane agreed
yesterday with calls by British scientists for
international cooperation to establish an early warning
system.
British Science Minister Lord Sainsbury in January set up a
taskforce, which has made a plea for a new $45 million
telescope in the southern hemisphere because scientists are
losing track of potential killer asteroids.
The three-member taskforce, headed by Dr Harry Atkinson, a
former head of the European Space Agency, has concluded
that the risk to life on Earth is not science fiction.
According to the team, a 100-metre asteroid hits Earth
every 10,000 years with the force of a 100-megaton nuclear
bomb. Every 100,000 years, an asteroid strikes with a force
equivalent to 10 million Hiroshima bombs.
They have recommended a global early-warning system and
more research into deflecting or striking threatening
asteroids to stop the sort of disaster blamed for wiping
out dinosaurs 65 million years ago.
Professor O'Kane said Australia and the rest of the world
had been "relatively lucky" to avoid having city areas
hit
by even small meteors. "The risk is real - the South
Australian outback and central Australia are pockmarked
with famous craters," she said.
Adelaide University has two space research telescopes in SA
- one at Ceduna on the coast, and a new 10-metre gamma ray
telescope at Woomera, being operated with the Japanese
Government to search for black holes and trace signals from
the origins of the universe.
According to Professor O'Kane, central Australia is the
only real option for siting the new asteroid hunter
telescope.
"Our only rival would be South America, but they can't
match our scientific expertise and our signal processing
capabilities," she said.
One of Adelaide University's top former space scientists,
Dr Duncan Steel, who is now working in Europe, has
constantly warned governments that Earth is in danger from
asteroids, but Dr O'Kane says political leaders still have
not recognised either the risk, or the high level of skill
available in Australia.
In 1996 the Howard Government withdrew funding for
Australia's only asteroid tracking research project at the
Siding Springs observatory in central New South Wales. In
1994, the SA Government announced plans for a $140 million
optical telescope at Freeling Heights in the Flinders
Ranges and a $200 million particle detector radio telescope
near Woomera, but they were not built.
Dr Robert MacNaught, who won NASA funding to continue
asteroid tracking from Siding Springs after Australian
government funding was cut, has warned there is a huge
blind spot because Canberra is not taking the threat
seriously.
"Up until now there has been no dedicated telescope in the
southern hemisphere," he said. "That means much of the
southern sky simply isn't being observed at all, and
objects that they've discovered in the north and which pass
into the southern sky become lost through not being
adequately followed up."
He said there had been "a general scientific consensus"
for
some time that Earth was in danger and has backed the
British calls for an early warning system and research .
"We need to keep tabs on them to calculate more accurately
what their orbits are and to predict their future passages
to the Earth."
c2000 The Age
=============
(3) NOAH'S KITCHEN UTENSILS DISCOVERED?
From National Geographic News, 25 September 2000
http://www.ngnews.com/news/2000/09/09252000/ballsea_3066.asp
BLACK SEA EXPEDITION RECOVERS OBJECTS OFF SEA FLOOR
By Staff Reporter
September 25, 2000
The National Geographic Society's Black Sea expedition, led
by Explorer-in-Residence Robert Ballard, has retrieved
several objects from an apparent archaeological site
located 300 feet below the surface of the Black Sea and
12 miles off the coast of Turkey. Organic samples have
also been recovered.
Ballard and his team are now working with the Turkish
authorities to arrange the transport of the items to a
laboratory where they can be tested. It is hoped that this
analysis will provide critical data as to the nature and age
of the objects. This process is expected to be concluded
in a matter of weeks.
"The Turkish government's contribution to the expedition
has been critical to its success and I am most appreciative
of Minister of Culture Dr. Istemihan Talay's ongoing
collaboration," Ballard said.
Dr. Talay granted the expedition a permit to recover
artifacts from the sea floor on Tuesday. Ten days ago the
expedition located what appears to be an archaeological
site more than 300 feet (95 meters) below the surface of
the Black Sea. Evidence suggests people must have thrived
in a coastal setting before a catastrophic flood inundated
the area many thousands of years ago.
The Geographic's Black Sea expedition is due to conclude at
the end of September.
Copyright 2000, National Geographic Society
===========
(4) EUROPEAN COMMSSION ON EARTH OBSERVATIONS FROM SPACE
From Andrew Yee <ayee@nova.astro.utoronto.ca>
The European Commission
Brussels, Belgium
September 22, 2000
Earth Observation from Space: More than a Technical Issue!
There is a critical need in Europe to make the policy on
Earth observation data and the underlying economic issues
more explicit and more user oriented. This is the message a
high-level expert team led by Professor Ray Harris
delivered to the European Commission and European space
data suppliers in Brussels last week. The message comes at
a time when space is very much on the Commission's agenda:
earlier this month EU research Commissioner, Philippe
Busquin discussed the EU-Russia Space Dialogue with the
Russian Space Agency, and he will also present a
communication on a European strategy for space, "Europe and
space: turning to a new chapter", to the Commission next
week. A coherent European approach to using satellite-based
tools for environmental monitoring will feature prominently
in this communication.
Professor Harris has been coordinating a working group
under the Eopole initiative (see below) for the last two
years. The group presented its findings to the Commission,
the European Space Agency, Eumetsat and national space
organisations at a workshop in Brussels on 12 September
2000. Their main recommendations were:
* to develop accounting measures to quantify the benefit of
Earth observation to the environment;
* given the enormous volume of data produced, to find
political, financial and institutional agreements to
support medium and long-term archiving of Earth
observation
satellite data;
* that no Earth observation mission should be launched
without a statement of its archiving policy;
* that special consideration should be given to
facilitating the trade and exchange of geographical
information, especially via the internet;
* to create an independent European 'think tank' to monitor
the economic and policy issues of Earth observation.
(See: Recommendations from the Eopole final workshop.
[Attached below])
The Eopole [1] initiative -- 'Earth observation data policy
and Europe' -- is based on the idea that data policy and
related economic and industrial issues are just as
important as many technical issues in the development and
maturity of the Earth observation sector. The Eopole
Concerted Action took shape during an Information Day
organised by the Commission's Research DG in June 1997 on
the subject of Community research opportunities in the
field of Earth observation applications. An independent
Eopole working group, financed by the Commission's
Environment and Climate research programme, was then
created to spend two years looking at current Earth
observation data policies and recommend improvements
with a distinctly European perspective.
The group included representatives from industry,
government and academia from eight different member states.
It has held seven dedicated workshops over the last two
years, culminating in the presentation of its
recommendations last week.
More information about the workshop and the Eopole
concerted action can be found at
http://www.geog.ucl.ac.uk/eopole/
For further information, please contact:
Dr Michel Schouppe, Research DG, Biodiversity and Global
Change Unit Fax: +32 2 29 60588
E-mail: michel.schouppe@cec.eu.int
Professor Ray Harris, Eopole co-ordinator, University
College of London
Fax: +44 171 5044293
E-mail: rharris@geog.ucl.ac.uk
Ms Piia Huusela, Press Officer, Research DG
Fax: + 32 2 29 58220
E-mail: piia.huusela@cec.eu.int
[1] Eopole -- 'Earth observation data policy and Europe'
(EC concerted action ENV4-CT98-0760)
*****
Recommendations from the Eopole final workshop
September 13, 2000
Looking at Earth observation as a major contributor to
global research and observing programmes, Eopole pointed
out the value of Earth observation data, not only in
strictly market terms but also in terms of its value to
society. In the current context of growing concern about
human-induced global change, it would be extremely helpful
to develop accounting measures to quantify the benefit of
Earth observation to the environment.
Within the next few years, Europe will be confronted with
storing and analysis of growing amounts of space data.
ESRIN (one of the four establishments of the European Space
Agency) will receive 160 gigabytes of Earth observation
data per day. SPOT data archived in Toulouse and Kiruna
comprises approximately 130 terabytes, which represents
only 50% of the 7 483 285 SPOT scenes in the SPOT Image
central catalogue as at 31 December 1999. The forthcoming
Meteosat Second Generation mission is expected to deliver
about 25 terabytes per year which means about 300 terabytes
for the whole mission. It is foreseen by CEOS (Committee on
Earth Observation Satellites, http://www.ceos.org/)
that by
the year 2009 there will be 126 missions flying 217
instruments for Earth observation from the many and growing
number of nations active in space. Against this background,
active steps should be taken to find political, financial
and institutional agreements to support medium and long
term archiving of Earth observation satellite data. In
parallel, Eopole suggested that no Earth observation
mission should be launched without a statement of its
archiving policy and that pricing policy should be the
servant of mission objectives.
With the current trend from imagery to geo-information,
users would directly take benefit from more compatible data
policies for Earth observation and other kinds of data.
Special consideration should be given particularly to
facilitate trade and exchange of geographical information,
notably via the internet.
A crosscutting recommendation by Eopole was the elaboration
of a European scale institute or 'think tank' with
independent and continuous capability to carry out
assignments on the economic and policy issues of Earth
observation. Space is a rapidly evolving sector that needs
continuous monitoring!
============================
* LETTERS TO THE MODERATOR *
============================
(5) ASTEROID 2000 DP107
From Petr Pravec <ppravec@asu.cas.cz>
Dear Benny,
I am delighted to read that 2000 DP107 has been found to be
a binary system by S. Ostro and his colleagues. The first
radar results published on IAUC 7496 suggest that its
characteristics may fit well with characteristics of other
binary near-Earth asteroid found from their double-period
lightcurves during several past years.
A list of six probable/possible NEA binary systems has been
published in a paper by me and colleagues in Icarus 146,
190-203, 2000. The radar detection of the binarity of 2000
DP107 is the first strong confirmation of the existence of
binaries among NEAs by the different technique, that it is
quite important. The evidence we have so far suggests that
about one fifth of NEAs are binary (see the Icarus paper
for details and references).
I and my colleagues here at the Ondrejov Observatory plan
to follow-up 2000 DP107 photometrically during following
nights to get lightcurve data to confirm the radar
detection of the binary system and to derive some of its
parameters that might not be well constrained by the
radar observations. I received an info from a few other
photometrists that they have already observed 2000 DP107,
so there are good chances that the radar observations will
be confirmed and supplemented from the photometry.
Best regards,
Petr Pravec
Ondrejov Observatory
==============
(6) NEO TASK FORCE REPORT: COULD THERE BE UNINTENDED
CONSEQUENCES?
From Ed Grondine <epgrondine@hotmail.com>
Hello Benny -
I suppose that on the UK impact report, like on most
things, people have their own individual views based on
their own experiences. Reading through the responses from
astronomers searching for NEOs, their consensus seems to be
that there is now an excellent chance that the recommended
3 meter telescope will be funded by the UK Government.
My own past experience has been in covering space programs
more generally, and what I have watched for some 15 years
now is many, many groups of scientists and engineers come
up with projects which they thought were great, necessary
to their countries' well being, and certain to be funded.
Most of these projects are now little more than a
collections of press releases, 4-color brochures, and
engineering studies. I have several bookcases full of them.
However, I don't think that the results of the UK NEO task
force is necessarily going to join HOTOL on those shelves,
for reasons I'm certain that the authors of the report had
little reason to foresee.
With many European countries still in chaos over tightening
fuel supplies and a flagging Euro, newspaper readers need a
little diversion. What better diversion than the humour of
stories like, "ASTEROID BOFFINS BLOW BIG ONE", or some
variant therof, wherein 3 of the UK's top scientists, when
assigned to report on the NEO hazard, miss the destruction
of large parts of South America some 4000 years ago.
"OOPS!", in at least half inch high letters, and if the
UK
team are good sports about it, and join with others in
laughing at their "little" mistake, they will realise
that
the report's omission of the perhaps most devastating
impact catastrophe in recent history (~350 megatons
equivalent of TNT - in other words, equivalent of 35,000
Hiroshima-sized atomic bombs!) could have unintended
consequences.
There's also a big difference between going to a pensioner
with a 75p increase last year and saying, "We want to spend
a few pence of your money to find asteroids", and saying
"We want to spend a few pence of your money to find
asteroids, and by the way, one of them pretty much
destroyed large areas of South America about 4,000 years
ago." In the case where the NEO Task Force is not
called
on the Rio Cuarto error, in my opinion, the recommended
funding in the UK may actually be in question. If this were
the outcome of their report, it would be a huge blow not
only to the British NEO community but to all NEO search
programs around the world.
Also, in that case, the result of the Task Force's report
in the U.S. is likely to be that those who, behind the
scence, wish to limit NASA NEO funding (say, to use NASA
money instead for Mars flight) will be able to claim that
"No one was ever killed by impact.", and point to the
Task
Force's report and Government inaction as proof.
This is real money we're talking about here, as the NASA
budget is some $13-$14 BILLION (that's BILLION as in
thousand millions) PER YEAR. In this case, the negative
result of the Task Force's report may actually be a
tremendous, enourmous, staggering, setback to the funding
of NEO search programs.
Nevertheless, the Task Force rightly called for more money
for research into historical impact events. Certainly such
funding (or perhaps a better use of the data and
information provided by the CCNet archive) would have
prevented them from making the Rio Cuarto blunder. Indeed,
and once again this is personal opinion, regardless of the
funding their astonomers get, the government which is going
to dominate the field of impact risk assessment is going be
the one which is willing to fund the vital research on
historical impacts (the fatal ones within the last 5,000
years or so). For the benefit of future government teams
from other European countries, whose aid the Task Force
recommended seeking, a list of suspected historical impact
events follows.
A SHORT LIST OF KNOWN AND SUSPECTED HISTORICAL IMPACTS
While most, BUT NOT ALL, of the impact events listed here
await detailed confirmation by field geologists, some of
them are currently known pretty well.
CLASS 8:
"A collision capable of causing localized destruction. Such
events occur somewhere between once per 50 years and once
per 1000 years."
Suspected and Known:
ca. 1584 BCE Destruction of Hittite forces under T'e
Hantilish
(Joshua impactor)?
ca. 520 BCE Destruction of Etruscan town of Volsinii?
ca. 1 BCE Brenham, Kansas (confirmed)
679 AD - Destruction of Colingiham Monastery?
ca. 800 AD - Impact in Baltic and death by local tsunami?
ca. 1321-1368 AD Erh River fall in China?
1450 AD - miss ("missed" people - no one killed) Wabar
1490 AD - Ch'ing-yang fall kills over 10,000 (possibly hail)?
(I can't find my copy of the list of what, 8?, small events
of the 1700's and 1800's so laboriously assembled from
obscure sources by one industrious researcher, and my
apologies to him.)
1868 AD - miss near Pultusk, Poland
1908 AD - miss in Tunguska
1930 AD - miss in Brazilian jungle
1947 AD - miss at Sikhote Ailin in Kamchatka
1972 AD - miss in South West Pacific
CLASS 9:
"A collision capable of causing regional devastation. Such
events occur between once per 1,000 years and once per
100,000 years."
Suspected:
ca. May 10, 2807 BCE - Masse sets this as the date of the
Indian Ocean impact and resulting tsunami?
580 AD - Destruction of Bordeaux region and city of Orleans?
585 AD - Destruction of "two islands in the sea"?
Date unknown - Destruction of Ainu?
Date unknown - St. Lawrence, destruction of major Native
American town?
ca. 750 AD - Great Raft formation, Louisianna, but unknown
if by impact, hurricane, or methane hydrate explosion
ca. 1200 AD - Bald Mountains?
ca. 1500 AD - Australian Great Wall of Water, with collapse of
Polynesian megalithic cultures on Ponhpei and
elsewhere?
CLASS 10:
"A collision capable of causing global climatic
catastrophe. Such events occur once per 100,000 years, or
less often."
Suspected and Known:
ca. 3114 BCE - Atlantic impact; Battle of Titans(?),
tsunami leading to flood myths, Stonehenge I
constructed, Mayan Calendar begins -?
ca. 2345 BCE - Ullikummi cometary impactor pretty much wipes out
Hurrians, dust loading leads to climate
collapse
ca. 2300? - Destruction of Mohenjo Daro, India?
ca. 2100 BCE - Rio Cuarto impactor and resulting climatic
collapse
(confirmed)
ca. 1160 BCE - General migration in eastern Mediterranean
follows report by observor from some
distance away of loud noise and rush of air?
ca. 536 AD - Dust loading leads to sub-Roman times becoming
sub-Roman. Possible combination of volcanic
and cometary dust
Whether all these are related to some one comet
disintegrating, or to some one asteroid parent body, awaits
field work by geologists. My opinion is that they do not.
I have also been informed by a researcher that initial data
on historical impact events in Africa will be published in
the very near future.
OPERATIONAL REQUIREMENTS FOR NEO DETECTION SYSTEMS:
For a 75 meter object, 45 minutes warning, with detailed
estimate of impact point, enough time to allow local people
to take shelter.
For a 150 meter object, 2 days warning, with detailed
estimate of impact point, enough time to allow evacuation
of area, including coastal areas subject to tsunami.
The objects' speeds are up to 70 kilometers per second for
comets, and 45 kilometers per second for asteroids. Range
requirements can be derived from travel time; optical and
sensor requirements, as well as decisions on basing
detectors in space, can be derived from the required range
and albedoes of different types of objects.
Longer warning times may allow deflection with either
conventional or nuclear charges.
EP
==============
(7) NOAH'S TAURID CONNECTION
From Leroy Ellenberger <c.leroy@rocketmail.com>
Benny,
I am leery of Ryan and Pitman's early Holocene Black Sea
flooding, while undoubtedly real, being related to Noah's
Flood (whatever it really was) because their scenario
ignores the midrashic story about the Flood coming when two
stars fell out of Mazal Khima, i.e., the Pleiades (which
Velikovsky erroneously, IMO, took to be Saturn), which
could be an early Taurid complex episode, since the Taurid
stream radiates from near Pleiades. See the penultimate
paragraph of my "An Antidote to Velikovskian Delusions"
which deals in part with Velikovsky's "Khima and
Kesil":
<http://abob.libs.uga.edu/bobk/velidelu.html>,
and the
notion that the biblical Flood story might be just an
astonomical allegory in terrestrial clothing.
Cheers,
Leroy
===========
(8) ON LUNIES, HERMIANS & OTHER MINI-PLANETS
From Duncan A. Lunan <astra@dlunan.freeserve.co.uk>
Dear Michael and CCNet,
Re: Small is beautiful
I second your motion but suggest a different nomenclature.
Admittedly in my book "Man and the Planets", based on
the
Solar System discussion project in ASTRA, the Association
in Scotland for Technology and Research in Astronautics, we
took the limit for inclusion in the tables to be 1000 km
diameter - but that was for convenience, not
definition.
Ceres went in the tables because its diameter was then
thought to be just over 1000 km. The subtitle was 'the
Resources of the Solar System' so we included many smaller
bodies including asteroids and down to Phobos-Deimos size.
In following what the late Dr. Krafft Ehricke called 'the
strategic approach to the Solar System' we suggested that
there should be a class name for inhabitants of Mercury,
the Galilean satellites, Titan and Triton, as having
similar surface gravities - estimates for Pluto and Charon
weren't then available. (But we thought they were unlikely
to go for some generic name like 'lunies' when they could
call themselves Hermians, Titans, Tritons etc.)
This I suggest would be the class of objects to be labelled
'mini-planets'. Now Pluto and Charon are well below the
rest in surface gravity, they could still have membership
in the class if we set the bottom limit at 1000 km
diameter, because that's the generally recognised limit
above which gravitational forces force them to be spherical
(though there are spherical objects like Phoebe which are
smaller).
'Microplanets' and 'microsatellites' could then be anything
below 1000 km. and anything below 1 km could be
'meteoroids' or 'mini-comets' according to composition.
Best wishes,
Duncan Lunan
----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
The CCNet is a scholarly electronic network. To
subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
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 http://abob.libs.uga.edu/bobk/cccmenu.html