PLEASE NOTE:
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CCNet DIGEST, 18 May 1998
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(1) "THE SECRETS OF ASTEROID PERIL" - BRITISH MEDIA
SMELLS A RAT
Benny J Peiser <b.j.peiser@livjm.ac.uk>
(2) DELAYED IMPACT, OR THE SECRETS OF ASTEROID PERIL
DAILY MAIL, 15 May 1998
(3) ASTEROIDS: PERILS AND OPPORTUNITIES
David Morrison <david.morrison@arc.nasa.gov>
(4) WHERE WE STAND ON THE NEO SURVEY
David Morrison <david.morrison@arc.nasa.gov>
(5) HOW METEORS MADE DEEP IMPACT DOWN UNDER
The Sunday Telegraph, 17 May 1998
(6) REGARDING SOUTHERN HEMISPHERE EVENTS
Steve Weintz <indy@local.net>
(7) SPACEGUARD UK - MEDIA EVENT
Jonathan TATE <fr77@dial.pipex.com>
(8) DON'T TRY THIS AT HOME
Graham Richard Pointer <grp1@st-andrews.ac.uk>
===================
(1) "THE SECRETS OF ASTEROID PERIL" - BRITISH MEDIA
SMELLS A RAT
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
In DEEP IMPACT, the world is kept in the dark about an
approaching
comet for almost a year by the American and Russian
administrations -
a n d the scientific community. Nobody in the DreamWorks
movie seems
to be bothered about this year-long cover up. One only wonders
why the
news is broken in the first place (other than for dramaturgical
reasons) before the Messiah mission lifts off.
Yet in the real world of NEO politics, journalists aren't as
restrained
and understanding as in the movies (thank goodness). A report in
London's DAILY MAIL on Friday openly accuses the astronomical
community
in the US of trying to cover up important scientific data on NEO
research - at least until NASA has the final word (and who is to
say
that 'earth-shattering' information would not be kept secret for
more
than two or three days if the US administration were to follow
the DEEP
IMPACT script).
Despite many inaccuracies in the DAILY MAIL's news story, I have
attached the article below. It shows that NASA's hasty and
ill-considered attempt to politically control scientific research
and
the way NEO related data is allowed to be reported by NASA-funded
astronomers (i.e. all American NEO researchers) can easily
backfire.
It would appear that NASA's failure to widely consult with the
scientific community has led to an own goal. Instead of
protecting the
integrity and trustworthiness of scientific and astronomical
research,
the interim procedures cast a dark shadow over the openess of
science
in the US.
It is essential, I believe, that NASA and the world's main
scientific institutions will come to an international agreement
on
these matters in due course if further damage to the integrity
and
openess of scientific research is to be avoided.
Benny J Peiser
========================
(2) DELAYED IMPACT, OR THE SECRETS OF ASTEROID PERIL
From the DAILY MAIL, 15 May 1998
Mail Foreign Service
If a giant asteroid is hurtling in the general direction of our
planet,
we will be the last to know about it. For astronomers have
decided that
the news would be too earth-shattering for ordinary mortals to
handle -
and likely to cause widespread panic.
In a week that sees the release of the film Deep Impact - a
fictional
account of just such a catastrophe - astronomers funded by
the
American space agency NASA have now agreed to keep asteroid and
comet
discoveries to themselves for 48 hours while more detailed
calculations
are made. The findings would then go to NASA, which would wait
another
24 hours befor going public.
The new procedures aim to avoid causing a repeat of a doomsday
alert in
March when astronomers reported that the asteroid 1997 XF11 could
collide with Earth in 2028. That apocalyptic prediction was soon
found
to be a mistake and there was virtually no chance of any such
impact.
The new interim procedures are not an attempt to hide anything
but to
make sure the information is accurate, claimed scientist Donald
Yeomans
of the Jet Propulsion Laboratoy, whose calculations helped dispel
the
fear that 1997XF11 was headed straight for Earth.
'It is an attempt for the small scientific community that tracks
these
objects to build a consensus, to determine if an asteroid is a
threat,'
he said.
Some scientists question the new push from NASA, saying quick
action
from astronomers is needed to determine an asteroid's danger. 'I
don't
think one should be secret about these things,' said Brian
Marsden, the
director of the International Astronomical Union [sic], which
made the
announcement about 1997XF11's projected collision with Earth. 'I
think
the public would be unhappy,' he added.
Some astronomers say releasing their discoveries quickly and
openly is
critical. When a new asteroid or comet is discovered, scientists
need
as many sightings as possible in order to plot its orbit
precisely and
gauge how close it may pass to Earth, they claim.
Meanwhile, other leading scientists have recommended that manned
missions to asteroids approaching Earth should be undertaken to
discover more about their possible threat.
The United States National Research Council also wants to see
investigations made by robot spacecraft. A report from the NRC
said:
'Five per cent of Earth-approaching asteroids are readily
accessible by
relatively short space flights.'
About 400 such asteroids and comets larger than a kilometre
across have
been indentified so far, but this is thought to represent only 10
per
cent of the total
(C) 1998 Daily Mail
=========================
(3) ASTEROIDS: PERILS AND OPPORTUNITIES
From David Morrison <david.morrison@arc.nasa.gov>
United States House of Representatives
Committee on Science
F. James Sensenbrenner, Jr., Chairman
George E. Brown, Jr., California, Ranking Democrat
www.house.gov/science/welcome.htm
May 15, 1998
Press Contact: Katy McGregor (202) 225-0461
katy.mcgregor@mail.house.gov
EXCERPT FROM THE SCHEDULE FOR THE WEEK OF MAY 18, 1998
The Subcommittee on Space and Aeronautics will hold a hearing
entitled
"Asteroids: Perils and Opportunities" on
Thursday, May 21, 1998 at 2:00
p.m. in 2318 Rayburn House Office Building. The purpose of
the hearing
will be to assess the dangers of Earth-impacting asteroids, to
determine
an appropriate level of response for analyzing this threat, and
to
examine the commercial opportunities for these large bodies of
minerals.
Testimony will also address the upcoming micrometeoroid shower
and
possible threats posed to satellites in orbit.
Witness list:
Dr. Clark R. Chapman, Institute Scientist, Southwest Research
Institute,
Boulder, CO.
Dr. John Lewis, Professor of Planetary Sciences, University of
Arizona
Lunar and Planetary Laboratory, Tucson, AZ.
Dr. William H. Ailor, Director, The Aerospace Corporation Center
for
Orbital and Reentry Debris Studies, El Segundo, CA.
======================
(4) WHERE WE STAND ON THE NEO SURVEY
From David Morrison <david.morrison@arc.nasa.gov>
NEO News (5/15/98)
WHERE WE STAND ON THE NEO SURVEY
by David Morrison with help from others
This is a good time to summarize where we stand in the search for
potentially hazardous NEOs. Also, as I indicated in yesterday's
NEO
News, The National Research Council Press Release of May 13 on
NEOs
could create some confusion about how many NEOs we have found and
what
the current rate of discovery is.
There has always been some ambiguity about what is meant by a NEO
(Near
Earth Object). Gene Shoemaker, who is responsible for many
of the
estimates of numbers of Earth-crossing asteroids (ECAs) and
comets,
used some special criteria to define ECAs, but roughly
these are equal
to the Apollo and Aten asteroids (currently Earth crossing) plus
a very
few of the innermost Amors (which can become
Earth-crossing). Most
people simply equate the Apollos and Atens with the Near Earth
Asteroids (NEAs).
To go from NEAs to NEOs, we must add the short-period comets with
perihelia inside the orbit of the Earth, but there are very few
of
these relative to the asteroids.
The May 13 NRC Press Release said: "Some 400
Earth-approaching
asteroids and comets larger than one kilometer in diameter have
been
discovered so far, but only an estimated 10 percent of the
objects this
size have been identified." The number 400 objects in fact
should refer
to all known NEOs, not just those larger than 1 km. In
contrast, this
is from the Executive Summary of the NRC COMPLEX report:
"Near-Earth objects (NEOs) are asteroids and comets with
orbits that
intersect or pass near that of our planet. About 400 NEOs are
currently
known, but the entire population contains perhaps 3000 objects
with
diameters larger than 1 km."
Jim Scotti reports on the current numbers of Apollos and Atens
(May
1998). He notes that the Minor Planet Center lists 240 known
Apollos
and 30 known Atens, for a total of 270 NEAs (Near Earth
Asteroids). Of
these, 122 are more than 1 km in diameter. It is this number of
122
known NEAs larger than 1 km plus about 10 short-period comets
that
should be compared with the estimates of the total number of NEOs
from
Shoemaker and others. Thus the fraction so far discovered is
about
132/2000 = 7%. I use 2000 rather than 3000 because we are
neglecting
the innermost Amors in these counts. Thus 7% is the completeness
of our
current knowledge of NEOs that might create a global ecological
disaster if they hit Earth.
Brian Marsden uses other criteria to define his list of
potentially
hazardous asteroids (PHAs). His orbital criteria are
more stringent
than simply being Earth-crossing, but he includes NEAs down to
about
200 meter diameter. The current number of known PHAs is 120.
The objective of the Spaceguard Survey (and also a science goal
in the
NASA Office of Space Science Strategic Plan) is to survey all
NEOs
greater than 1 km diameter. Alan Harris has estimated how long it
will
require to reach any given level of completeness at the current
discovery rate: until recently this rate corresponded to more
than a
century to reach 90% completeness, and up to two centuries for
95%
completeness. In the past few months the discovery rate has
climbed
primarily due to the US Air Force LINEAR search system. Harris
notes
that in February and March, 34 new NEOs were discovered, 16 of
them
larger than 1 km. Of these, 21 (12 larger than 1 km) were
found by
LINEAR. At this accelerated discovery rate, the anticipated
time for
90% survey completeness is down to about 50 years, and 95% to
about a
century. Thus we are for the first time within an order of
magnitude of
achieving the NASA and Spaceguard goals for discovery rate of 1
km or
larger NEOs. We are making progress!
=================================================
(5) HOW METEORS MADE DEEP IMPACT DOWN UNDER
From Electronic Telegraph, Sunday 17 May 1998
http://www.telegraph.co.uk:80
By Robert Matthews, Science Correspondent
THE new film Deep Impact - about meteors hitting the Earth and
causing
devastating ocean waves - may not be mere Hollywood hokum.
Scientists have found disturbing evidence that Australia suffered
just
such a fate only 200 years ago, in a catastrophe still recounted
in
Aboriginal legends. Deep Impact, which opened on Friday, centres
on
events following the impact of two comet fragments which create
colossal ocean waves that devastate America.
But while the film's spectacular special effects leave audiences
reeling, a growing number of scientists believe that they may be
all
too close to reality. Many astronomers accept that meteor impacts
pose
a serious threat, with evidence for scores of impacts having been
found
around the world - the most recent being in Siberia in 1908.
But with more than 70 per cent of the Earth's surface covered
with
water, most impacts take place over the oceans, causing huge
waves
known as tsunamis. Now researchers in Australia have found
impressive
evidence that a tsunami struck the coast of New South Wales in
the late
18th Century - and a meteor is seen as the most likely culprit.
According to Prof Ted Bryant, a geologist at the University of
Wollongong in New South Wales, analysis of sediment and boulders
along
the coast are consistent with a tsunami hundreds of feet high,
striking
at a speed of more than 200mph.
They have also found evidence for tsunamis hitting other sites
around
Australia. Prof Bryant said: "The geomorphic signatures of
such events
have been found on Lord Howe Island in the mid-Tasman Sea, along
the
north Queensland coast and along the northwest coast of Western
Australia. At the latter location, there is good evidence that a
recent
wave swept more than 20 miles inland, topping 200ft hills more
than a
mile from the coast."
The events are consistent with a legend still recounted by
Aborigines,
which speaks of a "white wave" falling out of the sky
and devastating
their culture. Until now, historians had linked the legend with
the
arrival of white settlers in the 1780s. However, according to
Prof
Bryant, a vast tsunami would give the impression of a white wave
falling out of the sky. While some researchers claimed that the
tsunami
was caused by a giant submarine mud-slide off the coast, others
believe
this cannot account for its size. Instead, they argue a meteor
impact
must be to blame.
Duncan Steel, a meteor impact expert at Spaceguard Australia,
Adelaide,
said: "There is lots of evidence of giant tsunamis, but no
known
terrestrial mechanism for creating them. Neither earthquakes nor
mudslides are big enough, but even small comet fragments detonate
in
the atmosphere at the height needed to create huge
tsunamis."
According to Mr Steel, evidence is now emerging to link the
Australian
tsunami to a swarm of meteors that have struck the Earth many
times
during recorded history. Known as the Taurids, the swarm has been
linked to a meteor storm detected in 1975 by instruments left on
the
Apollo missions, the 1908 impact in Siberia, and an account of an
apparent impact on the Moon recorded by a Canterbury monk in
1178.
Mr Steel said: "The Taurid impacts go through peaks and
troughs over
centuries. The dating of the tsunamis so far found is broadly
consistent with this cycle. If one struck today it would cause
billions
of dollars of damage, and kill many, many people." He added
that the
evidence linking meteor impacts to tsunamis underlined the
importance
of taking the cosmic threat seriously.
Mr Steel said: "Until recently the effect of the tsunamis
was just not
factored in. But now we know that they can be huge, and travel as
much
as 50 miles inland. The Atlantic presents a very large target,
and
cities on both sides would be devastated by an impact anywhere
between
New York and London."
(C) 1998 The Sunday Telegraph
Previous articles in the Sunday Telegraph
12 March 1998: [Connected] Are we sitting ducks in a cosmic
shooting
gallery?
28 October 1997: Taming the killer tsunamis
17 February 1997: American Association: 1,000ft wave threat from
volcanoes
16 October 1996: Bouncing meteorite sheds new light on America
20 May 1996: Mighty meteor catches astronomers unawares
===========================
(6) REGARDING SOUTHERN HEMISPHERE EVENTS
From Steve Weintz <indy@local.net>
Hi Benny
I've been intrigued by the recent discussions of possible
Southern
Hemisphere impact events recorded in oral tradition, in
particular one
correspondent's mention of the consequences for Andean
civilizations.
I did graduate work in Andean archaeology at the University of
Illinois
at Urbana-Champaign from 1991 to 1993, and archaeological
fieldwork in
the Titicaca Basin in 1992. The key long-term climatological data
for
the Central Andes comes from ice-cores taken from the Quelccaya
ice
cap, and several scholars, including Mike Moseley and Alan Kolata
have
argued for socio-economic effects from two major droughts, one
ca.
560-590 C.E., the other ca. 1100 C.E.
The Andes are an ideal region for the study of environmental
effects on
complex civilizations, due to its extreme and heterogeneous
topography
(the planet's richest fishing grounds, driest desert,
second-highest
mountain range and largest tropical rainforest juxtaposed within
a few
hundred kilometers of each other). The now-famous El Nino
phenomenon was
identified and first studied in this area, which boasts a
5000-year
record of complex civilization.
Regarding the 6th-Century event, a terrible El Nino appears to
have
caused massive flooding on the desert coast, which destroyed
irrigation
networks and melted adobe pyramids. Archaeologists see evidence
of major
changes in religious, political and settlement systems on the
North
Coast of Peru at this time, especially the decline of the Moche
civilization. During this period, a 30-year drought in the
higlands
apparently contributed to the florescence of the Middle Horizon
empires
of Huari and Tiwanaku.
We are just beginning to understand long-term and large-scale
environmental phenomena such as El Nino and Earth impacts, and no
doubt
it will take a long time to unravel their intricacies. The
relative
importance of environmental vs. purely cultural influences have
yet to
be worked out; however, the Andean region offers a compelling,
tested
region within which to test such ideas.
Regards,
Steve Weintz
indy@the-line.com
======================
(7) SPACEGUARD UK - MEDIA EVENT
From Jonathan TATE <fr77@dial.pipex.com>
Dear all,
You may like to know that a TV programme, entitled "Knocking
at
Doomsday's Door" will be screened on Tuesday 19 May at 10:40
pm on ITV.
The first part of the programme is pretty "off the
wall", but if you
can bear it, hold on for the remainder.
Jay Tate
Spaceguard UK
===============================
(8) DON'T TRY THIS AT HOME
From Graham Richard Pointer <grp1@st-andrews.ac.uk>
Dear Dr Peiser,
I saw this on the web at
http://news.bbc.co.uk/hi/english/sci/tech/newsid_93000/93678.stm
Graham Pointer
"It is an experiment you would never want to do," says
Mark Boslough, a
scientist at the Sandia National Laboratories in New Mexico. The
world's fastest supercomputer has simulated the worldwide
devastation
of an asteroid impact. Our science correspondent David Whitehouse
reports:
As Steven Spielberg's movie Deep Impact thrills audiences with a
fictional account of what would happen if an asteroid collided
with
Earth, scientists are using the fastest supercomputer to model an
impact with a 1.4km asteroid.
Using their extensive experience in modelling shock waves and
incorporating virtual reality techniques, scientists at Sandia
have
just completed the largest hyper-velocity impact simulation ever
performed.
In 1994, Sandia scientists simulated the impact of the fragmented
comet
Shoemaker-Levy 9 into the cloud decks of Jupiter. They were later
to
see their predictions come true as the Hubble Space Telescope
watched
the real impacts.
The asteroid was targeted 40km south of New York.
Within seconds, the asteroid is vaporised, the ocean floor
deformed and
hundreds of cubic kilometres of molten rock and superheated steam
are
thrown into the atmosphere.
New York is flattened.
Millions are dead.
Nuclear winter
The simulation takes into account the velocity of the incoming
asteroid, its make-up and strength, the densities of the
atmosphere,
the oceans and rock as well as the physics of shock waves.
Following the impact a shock wave would race around the Earth. In
North
America the heat would incinerate cities and forests almost
instantaneously.
Some debris thrown up into the atmosphere would come raining down
hours
later. Other debris would remain in the upper atmosphere for
longer.
The debris in the high atmosphere would reflect the sun's light
and the
world's temperature would lower. A global snowstorm may follow
initiating a "nuclear winter".
"A lot of major breakthroughs in science are going to come
from these
kinds of calculations," Boslough says.
He adds that computer simulations are a safe way to see what
would
happen during an impact. "It is almost like doing an
experiment - one
you could never do. One you would never want to do."
The recent short-lived news story about the possible impact of an
asteroid with the Earth in 2028 sparked intense scientific and
popular
interest world-wide.
Shortly after the initial alarmist statements it was shown that
the
asteroid in question would not hit our planet.
However, the United States National Research Council says in a
report -
started before the recent asteroid story - that astronomers
should find
new ways to release such information and avoid scare stories.
Some 400 Earth-approaching asteroids and comets larger than 1km
in
diameter have been detected so far but this is estimated to be
just 10%
of the total number of potentially threatening objects out there.
(C) 1998 BBC
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