PLEASE NOTE:
*
CCNet 97/2002 - 20 August 2002
------------------------------
"When the close Earth approach of a large NEA rises above
the
background level (the Palermo Scale value is then greater than
zero) we
know this event is out of the ordinary and hence of some
concern."
-- NASA/JPL, Impact Risk website
"What do asteroid impacts have to do with the Gaia
hypothesis?
Perhaps Gaia has gotten tired of being whacked by asteroids and
having to restart biological evolution over and over again.
Perhaps
she evolved technologically sophisticated, big-brained mammals
who can
travel in space as a way of protecting herself from asteroids.
Like
antibodies that protect the body from invading disease organisms,
humans can defend our Earth Mother against extraterrestrial
intruders.
Just a thought."
--Ronald Bailey, Reason Online, 31 July 2002
"Space Rock just misses" - or so said the headline on
the article in
Saturday's Herald Sun on the recent passing by of asteroid
2002NY40. A few
days earlier, ABC Western Plains, the voice of Australia in rural
NSW,
advised "Don't panic . . . yet" as they, too, discussed
our looming
encounter with said space rock. Don't panic indeed. This near
miss, the
latest in a long line of asteroid scares, may well have been a
close thing
in astronomical terms, but to us on the ground, the fact that it
missed
Earth by well over half-a-million kilometres hardly seems to
justify
the use of the words "just misses" let alone the
wastage of the
necessary column inches to do so. Asteroid near-misses are this
year's Y2K
drama - promoted, hyped and blown out of all proportion by
bespectacled gents in white laboratory coats doing all they can
to boost
their funding applications."
--John Weldon, The Age (Australia), 20 August 2002
(1) ASTEROID FLYBY SEEN WORLDWIDE
Sky & Telescope, 19 August 2002
(2) IMPROVED MODELLING OF ASTEROID TSUNAMI
Michael Paine <mpaine@tpg.com.au>
**MORE COMMENTS ON 2002 NT7**
(3) DEFENDERS OF EARTH: ARE HUMANS GAIA'S IMMUNE SYSTEM?
Reason Online, 31 July 2002
(4) ARMAGEDDON: COULD IT BE CLOSER THAN WE THINK?
The Express, 2 August 2002
(5) ASTERODDS PLAYING UP?
The Mirror, 2 August 2002
(6) BEWARE OF BUSES FROM DEEP SPACE
Space Daily, 31 July 2002
(7) WHAT THE NT7 AFFAIR IS TELLING ME
Daniel Fischer <dfischer@astro.uni-bonn.de>
(8) 2002 NT7 IN SOUTH AFRICAN MEDIA
Jon Richfield <richfield@telkomsa.net>
(9) A BIT OF NEO HISTORY: REVERSED ROLES AS BBC CRITCISE NASA
OVER ASTEROID SCARE
BBC News Online, 4 November 2000
(10) AND FINALLY: WHY SMART PEOPLE BELIEVE WEIRD THINGS TOO
Scientific American, September 2002
==============
(1) ASTEROID FLYBY SEEN WORLDWIDE
>From Sky & Telescope, 19 August 2002
http://skyandtelescope.com/observing/objects/asteroids/article_713_1.asp
By Paul Deans
>From Uzbekistan and the Crimea to the UK, across North
America, and on to
Hawaii, amateur astronomers around the world had fine views of
the close
flyby of asteroid 2002 NY40 last weekend.
The experience of David Nance (Huntsville, Alabama) was typical
of the many
reports received at Sky & Telescope. He wrote: "I found
2002 NY40 easily and
followed it for about 30 minutes. It was very bright (I'd
estimate it at
magnitude 9.5), and it was really spectacular sailing through the
eyepiece,
changing the patterns I formed with it and the framework of
stars. My wife
thought it was neat since it was so obviously not a 'fixed' star
... it
looked a lot like a slow moving satellite on a really weird
trajectory."
Chris Stephan, an AAVSO observer in Sebring, Florida, used his
14.25-inch
reflector with a 32-mm wide-field Erfle eyepiece to find and
track the
asteroid. "I found the object very quickly and was amazed at
how fast it was
traveling. I was hoping to catch a chance stellar occultation,
but during
the time period I observed, it just passed between stars with a
few very
close appulses. Another interesting thing was that the asteroid
seemed to
fluctuate slowly in brightness by about 0.2 magnitude within a 4
to 5 minute
time period."
Most observers were surprised by the rapid motion of the asteroid
through
their field of view, and some also reported that 2002 NY40 had a
definite
color. "I never anticipated how quickly the asteroid would
sweep through the
field even though advanced planning revealed such," wrote
Clay Sherrod who
watched from his observatory in Conway, Arkansas. "In the
4-inch guide
refractor of the scope, the motion of this object was just
incredible, not
unlike that of a slow-moving satellite seen through the same
telescope. The
Near Earth Object was distinctly reddish in color; this was
unmistakable
when it passed very near similarly bright stars within the visual
telescopic
field of view."
Not everybody employed a large-aperture telescope at high power
to watch the
flyby. Becky Ramotowski of San Antonio, Texas, used her 80-mm
refractor and
a 32-mm eyepiece to follow the asteroid. "I was able to find
it easily after
picking out a star field and just waiting for it to pass
through," she
wrote. "It was quite amazing to visually watch it zoom
through space! I did
not take any images, I just enjoyed the 'ride', and was it ever a
fast one!
It made for an exciting evening of viewing, especially since we
had a nice
ISS and Hubble pass to get us warmed up!"
After observing 2002 NY40 with his 8-inch telescope, Timo Karhula
(Sweden)
decided to try using binoculars. "At local midnight (22:00
UT), when the
asteroid moved into Vulpecula, I pointed my 20 x 100 binoculars
towards it.
It took a couple of seconds to discern a change in its position,
but then
the motion was obvious. Then I took out my 7 x 50 binoculars,
targeted M71,
and waited. At 22:43 UT, I could just see the 10th-magnitude
asteroid. With
the hand-held 7 x 50s I was not able to notice the immediate
movement of
2002 NY40, but after a few minutes I could see the speck's
motion."
The most remote observation report received so far comes from Tom
Krajci in
Uzbekistan. "Several of us had a blast finding and tracking
the motion of
2002NY40 the evening of August 17th in Tashkent, Uzbekistan. Our
first
attempts at finding this fast mover were unsuccessful until we
got more
methodical. Using JPL HORIZONS we generated accurate coordinates
for every
five minutes. It was crucial to use the proper latitude and
longitude of our
location. Next we plotted the expected locations of the asteroid
on the
appropriate Uranometria chart, star hopped to that region (using
my 10-inch,
f/7.2 home-made Dobsonian), and kept a patient watch for a moving
interloper. After two minutes we confirmed the asteroid and
followed it for
about 30 minutes. The asteroid's motion was most obvious when it
passed near
a star."
Thanks to everyone who submitted observing reports to Sky &
Telescope.
Copyright 2002 Sky Publishing Corp.
===========
(2) IMPROVED MODELLING OF ASTEROID TSUNAMI
>From Michael Paine <mpaine@tpg.com.au>
Dear Benny
In June Los Almos National Laboratories issued a press release
(http://www.lanl.gov/worldview/news/releases/archive/02-064.shtml)
that
described new advanced modelling of tsunami generated when a
large asteroid
strikes the deep ocean. The work is being conducted by Galen
Gisler and Bob
Weaver from the LANL's Thermonuclear Applications Group
(!), and Michael Gittings from Science Applications International
Corp. The
article stated: "The team's effort builds on the pioneering
research of Los
Alamos' Charles Mader and Dave Crawford of Sandia National
Laboratories.
More accurate models of tsunami behavior are now
possible..."
I have since heard from Charles Mader, who has been using the new
software.
He is excited about the improvement: "...to do the modelling
with all known
Physics is a dream come true".
The big question is whether the modelling changes the estimates
of tsunami
effects across ocean basins. It is too early to answer this
question (which
in any case will no doubt be the subject of journal papers) but
Charles
advises that the tentative results are that the water crater
(cavity) from a
1km diameter asteroid is the same as previous work but the
collapse of this
cavity is complicated by turbulent water motion and breaking
waves. As a
result the maximum height of waves at the edge of the crater is
about twice
that of the previous modelling work (by Crawford and Mader).
However, the
waves have a shorter period than the previous work and will
therefore
dissipate faster (the same general results have been obtained
with 500m and
250m asteroids). The end result is that tsunami from a 1km
asteroid "will
not present a significant hazard after they run across an ocean
basin". This
is the same conclusion as Crawford and Mader reached previously.
As I point
out on my tsunami web page
(http://www4.tpg.com.au/users/tps-seti/spacegd7.html)
this differs from
modelling conducted by Ward and Asphaug.
I am looking forward to the release of some official results of
the latest
work and hope that it will resolve some of the differences.
regards
Michael Paine
The Planetary Society Australian Volunteers
=============
(3) DEFENDERS OF EARTH: ARE HUMANS GAIA'S IMMUNE SYSTEM?
>From Reason Online, 31 July 2002
http://reason.com/rb/rb073102.shtml
By Ronald Bailey
The Gaia hypothesis, which holds that Earth is a living organism
in its own
right, typically has been used to highlight man's role in messing
up the
environment. But if the latest warning of a possible ecological
catastrophe
turns out to be accurate, people could end up helping Gaia rather
than
harming her.
The Gaia hypothesis--named after the Greek word for the Earth
goddess, also
translated as "Earth Mother"--was devised in the 1970s
by atmospheric
chemist James Lovelock and microbiologist Lynn Margulis. In Gaia:
A New Look
at Life on Earth, Lovelock and Margulis wrote, "The entire
range of living
matter on Earth from whales to viruses and from oaks to algae
could be
regarded as constituting a single living entity capable of
maintaining the
Earth's atmosphere to suit its overall needs and endowed with
faculties and
powers far beyond those of its constituent parts." They said
Gaia could be
defined as "a complex entity involving the Earth's
biosphere, atmosphere,
oceans, and soil; the totality constituting a feedback of
cybernetic systems
which seeks an optimal physical and chemical environment for life
on this
planet."
Most evolutionary biologists reject the Gaia hypothesis as an
unscientific,
although poetic, metaphor. But let's not let such quibbles
trouble us today.
According to the Gaia hypothesis, the history of life on Earth
can be
regarded as a progressive modification of the planet's chemistry
and
temperature by biological organisms acting in ways that enhance
their own
flourishing. For example, Earth's atmosphere was modified over
billions of
years by photosynthetic microorganisms from one that was
predominantly
carbon dioxide and methane into its current oxygen-rich state.
This
oxygen-rich atmosphere apparently set the stage for the evolution
of
multicellular life that took off in earnest during the
"Cambrian explosion"
some 540 million years ago.
In the millions of years following the Cambrian explosion, Gaia
took out all
the stops, and the earth saw a vast diversification of life and
finally the
colonization of land by plants and animals. Then, 250 million
years ago, the
Permian party came to a catastrophic end in which 95 percent of
Earth's
species were wiped out. Gaia picked herself up and started over.
Dinosaurs
and flowering plants eventually evolved to dominate the landscape
in the
Cretaceous Period (146 to 65 million years ago). At the time, our
tiny
mammalian ancestors were scrambling about the leaf litter, trying
to avoid
becoming dinosaur snacks. The cornucopia of Cretaceous life came
to an
abrupt end 65 million years ago, when 70 percent of all species
became
extinct.
The leading explanation for these mass extinctions is the havoc
caused by
asteroids slamming into the earth. The asteroid that brought the
Cretaceous
Period to a close is thought to have been 10 miles wide, creating
the
110-mile-diameter Chicxulub crater just off Mexico's Yucatan
peninsula. The
massive Permian extinction is thought to have been caused by an
asteroid 10
times bigger.
It's inevitable that Earth will be struck again. In 1908 a small
comet or
asteroid, about 165 feet in diameter, exploded over the remote
Tunguska
region of Siberia, releasing energy equivalent to 15 megatons of
TNT, 1,000
times stronger than the atomic bomb dropped on Hiroshima. In 1989
an
asteroid measuring a quarter of mile in diameter missed Earth by
just
400,000 miles. In 1994 the house-sized asteroid XM1 was spotted
only 14
hours before passing within 65,000 miles of Earth, well inside
the moon's
orbit of 238,000 miles. In June an asteroid the size of a soccer
field
missed Earth by 75,000 miles.
Scientists estimate that an asteroid with a diameter of a
kilometer (0.62
mile) could destroy civilization by drastically changing the
earth's climate
after impact and kill one-quarter of the world's population. This
disaster
scenario was popularized in 1998 by two mediocre movies, Deep
Impact and
Armageddon.
So far astronomers have identified over 26,000 asteroids in our
solar
system. The 1,700 or so that regularly pass close to Earth's
orbit are
designated Near Earth Objects, or NEOs. Six hundred NEOs measure
more than a
kilometer in diameter. The National Aeronautics and Space
Administration's
Jet Propulsion Laboratory helpfully lists more than a score of
upcoming near
misses for those who have a morbid interest in such things.
The latest scare occurred last week with the detection of
asteroid 2002 NT7,
which measures more than a mile in diameter. Initial calculations
showed
that there was a small probability that it might hit the earth on
February
1, 2019. Fortunately, subsequent analysis found that civilization
will be
spared until at least February 1, 2060, when there is a very tiny
chance the
asteroid will hit us. In the meantime, NASA and the European
Space Agency
are increasing their monitoring of NEOs and thinking of ways to
deflect or
blow up any asteroids that threaten to smash into Earth.
What do asteroid impacts have to do with the Gaia hypothesis? In
Gaia: A New
Look at Life on Earth, Lovelock asked, "To what extent is
our collective
intelligence also a part of Gaia? Do we as a species constitute a
Gaian
nervous system and a brain which can consciously anticipate
environmental
changes?"
Perhaps Gaia has gotten tired of being whacked by asteroids and
having to
restart biological evolution over and over again. Perhaps she
evolved
technologically sophisticated, big-brained mammals who can travel
in space
as a way of protecting herself from asteroids. Like antibodies
that protect
the body from invading disease organisms, humans can defend our
Earth Mother
against extraterrestrial intruders. Just a thought.
Ronald Bailey, Reason's science correspondent, is the editor of
Global
Warming and Other Eco Myths (Prima Publishing) and Earth Report
2000:
Revisiting the True State of the Planet(McGraw-Hill).
Copyright 2002, Reason Online
=========
(4) ARMAGEDDON: COULD IT BE CLOSER THAN WE THINK?
>From The Express, 2 August 2002
IT IS ONLY A MATTER OF TIME BEFORE OUR LUCK RUNS OUT, YET EXPERTS
ARE
WARNING THAT WORLD LEADERS ARE NOT TAKING THE THREAT OF AN
ASTEROID STRIKE
SERIOUSLY ENOUGH
AS YOU read this, scientists are preparing to dive far below the
surface of
the North Sea to explore an exciting discovery. It's not the
elusive giant
squid, nor a mystical city. They are looking at a huge asteroid
crater,
seven miles wide and 900 ft deep. Just off the coast of
Scarborough, it is
thought to have been been caused 60 million years ago by an
asteroid 1,500
ft wide. The impact rings around it have been unusually
well-preserved by
sediment and geologists believe it could reveal vital information
about
asteroids like the one thought to have wiped out the dinosaurs 65
million
years ago.
Never has it seemed more important to discover everything we can
about large
chunks of rock that hurtle towards Earth. Last week scientists
revealed that
a mile-wide asteroid was heading towards us at more than
60,000mph.
Astronomers feared that on February 1, 2019, it would hit us with
the
violence of a million H-bombs. Codenamed 2002 NT7, it is one of
countless
mountain-sized bits of cosmic debris that circle the sun between
the orbits
of Mars and Jupiter.
Luckily, it is now thought that 2002 NT7 will not hit us in 2019
- new
observations suggesting that it will, instead, blast through the
Earth's
atmosphere on February 1, 2060.
It's too early to start panicking just yet. As astronomers pin
down the
precise orbit of 2002 NT7, the chances are it will turn out to be
on a
course that misses Earth - although it may be an uncomfortably
close shave.
But it is not too early to start finding out exactly where all
the other
thousands of Earth-crossing asteroids are - and to keep a very
close watch
on them.
For this is just the latest of a series of alerts about this
cosmic threat
to our planet.
The vast majority never come near us but there are many thousands
that cut
across the orbit of the Earth, threatening to strike with
devastating
consequences. In April, astronomers in America discovered another
asteroid
on course for a possible collision in 2880. And only last month,
a 100-yard
wide asteroid called 2002MN came within 75,000 miles of hitting
our planet -
an astronomical hair's breadth. Worryingly, it was only
discovered after it
had made its closest approach.
All the experts agree that it is only a matter of time before our
luck runs
out yet governments around the world have so far spent only token
amounts of
money on finding out more about this danger. Two years ago, the
UK
Government set up a task force to decide what steps Britain
should be taking
over these Near Earth Objects (NEOs). Its final report called for
the
construction of sophisticated telescopes dedicated to tracking
down NEOs and
co-operation with other countries in drawing up plans for dealing
with the
threat.
Earlier this year Lord Sainsbury, the Science Minister, unveiled
the
Government's response: an information centre in Leicester.
Such a reaction seems almost like a parody of the Government's
penchant for
spin over substance. Earth under attack? No problem: just give a
boffin a
desk in Leicester and a heap of glossy brochures to hand out.
Others will regard it as an appropriate response to a blatant
attempt by
scientists to whip up funding with a ludicrous scare story.
After all, when did you last read of an asteroid devastating vast
areas of
the Earth?
In fact, newspapers have unwittingly carried reports of just such
events
many times in the last century. In July 1908, correspondents
reported
spectacular scenes over Europe, with nights so bright people were
playing
golf at two in the morning. At the same time, earthquake stations
picked up
a massive disturbance from somewhere in Siberia. Years later,
when Soviet
scientists finally reached the epicentre of the disturbance near
the
Tunguska River, they found a scene of utter devastation.
Hundreds of square miles of trees had been flattened, their
trunks scorched
and blackened. They also found a mile-wide crater.
THE so-called Tunguska Event of 1908 is now known to have been
caused by a
200ft meteor crashing down with the violence of 20 H-bombs. No
one was
killed, but had the impact occurred a few hours later, it would
have struck
the heart of Europe, killing millions. Had it hit the sea - which
covers two
thirds of the planet - it would have been no less devastating.
The shock
wave or tsunami would have drowned whole cities on the Pacific
coast from
Japan to California.
No astronomer seriously doubts that far bigger NEOs can and do
strike the
Earth.
Evidence for more than 200 impact craters has been uncovered
around the
world.
In 1978, a geophysicist working for the Mexican national oil
company found
remnants of a colossal crater deep under the coast of the Gulf of
Mexico.
Measuring 110 miles across, it was gouged out by a huge impact
around 65
million years ago. Scientists now think that the six-mile-wide
meteor that
formed the crater helped drive the dinosaurs into extinction.
Humans are not immune from the effects of NEOs. Evidence has
recently
emerged of a devastating impact in the Middle East which may have
triggered
the otherwise mysterious collapse of early civilisations around
2,300 BC.
Satellite images of southern Iraq have revealed a two-mile-wide
circular
depression which bears the hallmarks of a fresh impact crater. If
confirmed,
it would point to the region being hit by an NEO with the
violence of
hundreds of H-bombs around 4,000 years ago.
What no one yet knows is how big a risk we face from NEOs today.
Estimates
suggest that the risk of a devastating impact within the next 100
years
could be as high as one in 1,500.
The problem is that no one knows for sure. At the last count,
around 2,000
NEOs had been identified and their orbits calculated. Around 350
of them are
potentially hazardous, following paths that bring them a little
too close to
the Earth for comfort. Of these, about 100 are so big that their
impact
would be equivalent to the explosion of around a million H-bombs.
Knowing if we are on course for an NEO collision is vital. Given
enough
warning, it should be possible to deflect an asteroid off a
collision course
and avert disaster - a scenario that was played out in the film
Armageddon,
starring Bruce Willis. One way to do it is to send a rocket
packed with
nuclear explosive to intercept it. The aim is not to blow the
thing to
pieces: that would leave us facing multiple impacts. Instead, the
idea is to
detonate the warhead and vaporise material off one face of the
NEO. The
resulting jet effect would gently push it off its collision
course. Done
early enough, the detonation of a single H-bomb would be enough
to do the
job.
Some objects could even be deflected by landing rockets on them
and using
their engines to send them out of harm's way.
Science fiction? Not at all: last year, Nasa landed its Near
Earth Asteroid
Rendezvous (NEAR) probe on a 21-mile-long chunk of rock known as
433 Eros.
In 2005, Nasa plans to carry out a similar mission to a comet,
firing a
probe deep into its surface.
Some scientists think the time has come to begin practising the
art of
saving the planet but most think the priority is to find out how
many NEOs
are out there - and that requires a global network of telescopes
powerful
enough to spot a hill-sized chunk of rock millions of miles away
and track
it, so its orbit can be worked out. The task is about more than
just
compiling a catalogue of every sizeable NEO.
Constantly jostled by gravity, even apparently harmless NEOs can
drift on to
collision courses in as little as 30 years. Add in the danger of
comets
wandering in from beyond our solar system and the need to set up
a global
early warning system seems beyond argument.
With the impact threat, the price of security is constant
vigilance. Yet
until now, the role of cosmic lookouts has fallen to a handful of
dedicated
professionals and amateurs. The amount of sky they can cover is
only a
fraction of the vast expanse of space, which means there are
still some
asteroids we cannot see.
ONLY when governments take the NEO threat seriously will our
planet get the
early warning system it needs and for that to happen, politicians
need to be
convinced of the need for action.
With one globally devastating impact expected only every 100,000
years,
dealing with NEOs is not about to become an election issue but
this
overlooks the appalling death toll predicted from such an impact
- expected
to run into hundreds of millions. Cosmic impacts thus produce a
long-term
average toll of around 1,000 deaths a year - several times the
average
fatality rate for air crashes, which every government takes very
seriously.
Responding to last year's task force report, Lord Sainsbury
declared that
Britain could "take an lead" in dealing with the
threat. So far, our
Government has followed everyone else in failing to take the
issue
seriously. We must all hope that it won't take a 10 megaton
impact to wake
governments up to the very real threat that lurks in the depths
of space.
Robert Matthews is a physicist at Aston University, Birmingham.
Copyright 2002, The Express
================
(5) ASTERODDS PLAYING UP?
>From The Mirror, 2 August 2002
By Kevan Furbank
RELAX, folks. The asteroid threat has been downgraded. The
chances of the
lump of celestial rock turning planet Earth into the shape of a
lozenge have
been reduced to one in 250,000.
Most unlikely, you would have thought. But it is still 56 times
more likely
than winning the Lottery jackpot, the odds of which I am sure you
are
painfully aware are 14million to one.
Yet people do win, the most recent and close to home being
Limavady feller
Stephen Boyd. He scooped pounds 1.5million but is not going to
give up his
pounds 10,000-a-year fizzy drinks job.
Makes you wonder what's in his fizzy drinks.
Statistically, lucky Stephen should have been hit by 56
asteroids. To my
certain knowledge, however, he carries no asteroid-induced
injuries.
But I would advise him to wear a hard hat from now on.
This leads me on to the bookmakers who have given a chap odds of
20million
to one that Elvis Presley will turn up riding Shergar and then
play Lord
Lucan at Wimbledon.
Even less likely, you would have thought, than winning the
Lottery. But the
bookies are not so sure - they've limited the size of the bet to
5p, just in
case.
But even this scenario becomes a certainty compared to the odds
against
being struck by lightning seven times on seven different
occasions - and
surviving.
It's about one to 165,000 to the power of 7, a figure so high I
can't write
it out in full because our printing press would run out of
zeroes.
Yet it happened - to American park ranger Roy Sullivan between
1942 and
1983.
The first strike shot through his leg and knocked his big toenail
off. In
1969, a second strike burned off his eyebrows and knocked him
unconscious.
Another strike just a year later left his shoulder seared.
In 1972 his hair was set on fire and Roy had to dump a bucket of
water over
his head to cool off.
In 1973, another bolt ripped through his hat and hit him on the
head, set
his hair on fire again, threw him out of his truck and knocked
his left shoe
off.
A sixth strike in 1976 left him with an injured ankle. The last
lightning
bolt to hit Roy Sullivan sent him to the hospital with chest and
stomach
burns in 1977.
Sadly, Mr Sullivan committed suicide on the reasonable assumption
that God
had it in for him.
But he will be remembered for cheating fantastic odds equivalent
to being
caught in a hailstorm of asteroids, winning every lottery draw
until the
money runs out and Elvis getting the Wimbledon doubles title -
partnered
with Shergar.
The moral of this story is that statistics - like the drinks
price list in a
lapdancing club - bear absolutely no relation to reality; that
the most
unlikely occurrences are very likely to occur; and if an asteroid
has got
your name on it, your number is well and truly up.
Copyright 2002, MGN Ltd
============
(6) BEWARE OF BUSES FROM DEEP SPACE
>From Space Daily, 31 July 2002
http://www.spacedaily.com/news/deepimpact-02n.html
by Michael Paine
Sydney - Jul 31, 2002
There was a flurry of interest by TV news studios and newspapers
last week
when it was realised there was a slight risk that a space rock,
designated
2002 NT7, some two kilometres across might hit the Earth in 2019.
As
expected, by the end of the week additional observations had
pinned down the
orbit sufficiently for astronomers to rule out any possibility of
an impact
in 2019.
A debate ensued about whether the initial, tentative calculations
should
have been made available to the public and whether the media
reporting was
sensationalised.
When the dust settles, so to speak, there are a few points to be
made about
this object.
Firstly, a 2km asteroid is something to be taken very seriously.
The global
climatic effects of an impact anywhere on Earth would be
devastating for our
civilisation and would probably lead to the death of more than a
quarter of
the world's population. It would however, not be nearly as severe
as the
impact 65 million years ago that is associated with the
extinction of the
dinosaurs.
Secondly this object has an unusual orbit and it appears to be
fortunate
that it was picked up by the LINEAR "Spaceguard"
telescopes. With current
search efforts we can expect a large proportion, perhaps 80%, of
Near Earth
Asteroids of this size to have been discovered to date so it was
a bit of a
surprise that 2002 NT7 turned up.
Thirdly, a world-wide effort by astronomers, who were mostly
amateurs, was
needed to track the asteroid so that calculations could be
refined and the
object eventually declared "safe" (there is still a
slight risk of an impact
in 2060, but once again further observations are expected
to eliminate that possibility).
Estimates of the average impact rate of asteroids vary
considerably. During
the next 50 years there is perhaps a one in ten chance of an
impact actually
occurring but this would likely be an airburst event such as the
60m
diameter asteroid that flattened 2000 square kilometres of forest
in Siberia
in 1908.
Small asteroids collide with the Earth (or more correctly, the
atmosphere)
much more frequently than large ones. They are not a threat to
our
civilisation but could easily destroy a city with an explosion
similar to
that of a nuclear bomb.
For now NASA has decided to concentrate on asteroids one
kilometre and
larger that pose a global threat. It aims to have detected 90% by
2008. The
search effort also picks up many of the smaller asteroids so that
after ten
years it is expected that about 20% of asteroids 200m or
larger will have been found.
Since an impact by an object this size could devastate a small
country a 20%
completion rate is likely to be seen as inadequate by future
generations and
the Spaceguard effort will no doubt be stepped up.
Up until 1996 Australia made a significant contribution to
Spaceguard,
accounting for about one third of discoveries. In that year
Australian
government funding stopped and the program closed down. In
January this year
more than 90 scientists from around the world signed an open
letter
to the Australian government supporting the revival of funding
for
"Spaceguard Australia". Most were experts in the field
of asteroid research
and the letter was a remarkable, spontaneous show of solidarity.
Nevertheless during a subsequent TV interview, Australian Science
Minister
Peter McGauran dismissed the search for Earth-threatening
asteroids as a
"fruitless, unnecessary, self-indulgent exercise".
Fruitless? Spaceguard is finding objects like Asteroid 2002 NT7,
and can
provide decades of warning - sufficient time to nudge an
Earth-threatening
asteroid into a safe orbit.
Unnecessary? Only if we take the gamble that an impact will not
happen in
our lifetimes. Sadly it is all too easy for politicians to ignore
our
responsibilities to future generations - the ones who would
benefit most
from observations made today.
Self-indulgent? That is plain insulting to the many scientists
who have
recognised that the Earth is at risk and who have dedicated much
of their
career to addressing the hazard. It is also insulting to the
hundreds of
amateur astronomers who donate their time to follow-up
observations.
In fact, the letter arose from a statement by a spokesperson for
Minister
McGauran who indicated that funding would be reconsidered,
following another
asteroid "near miss" around Christmas time.
Clearly asteroids do pose a hazard to our civilisation. The
Spaceguard
system has been shown to be effective in detecting objects like
Asteroid
2002 NT7 but there are many more that we should be looking for.
An
international effort is needed and, in particular, the current
blind spot in
the southern hemisphere needs to be addressed.
Yes - there is an asteroid with our name on it. It might hit
tomorrow or not
for a thousand years. Every telescope that is added to the
international
Spaceguard program will reduce our chances of being caught with
insufficient
time to avoid the collision.
By reviving the search for rogue asteroids, Australia would
fulfill its
responsibility to protect its citizens, to help protect other
citizens of
the world and to provide a possible gift of survival for future
generations.
Michael Paine is a consulting mechanical engineer based in
Sydney. He is a
member of the Planetary Society.
==========
(7) WHAT THE NT7 AFFAIR IS TELLING ME
>From Daniel Fischer <dfischer@astro.uni-bonn.de>
sent: 31 July 2002
Dear Benny,
The more I think about the "2002 NT7 affair", the more
I am confused - not
least by your assessment of the events in CCNet of July 26, item
13, and the
quotes therein. There seems to be a widespread belief in the
community that
2002 NT7 was unique (and thus newsworthy) as the first NEO in the
history of
Sentry & Co. that reached a Palermo value of greater than
zero or even
approached it. You quote a statement from the Sentry site that
claims that
prior to NT7 "the risks posed by the potential impacts
identified by Sentry
have all been well below the background level" - and this is
simply not the
case.
The exotic example of 1950 DA aside (because of the extremely
long lead
time), there was at least one other case in which the impact
probability of
an asteroid reached about half the background value - and stayed
at that
"threat level" for several weeks: 2002 CU11. No IAU
announcement was made
about it. On the other hand the IAU protocol *did* kick into
action
pre-Sentry in late 2000 when the small NEA 2000 SG433 had reached
an impact
probability of 1:500 for 2030 - which was (if one assumes an
impact of a 50
meter object every 200 years) only 1/75 of the background,
representing a
Palermo level of -1.9. Back then the media impact had been
immense, as
reflected in CCNet of Nov. 7 to 9, 2000.
Who knows how many cases like 2002 CU11 have come and gone
unnoticed, i.e.
were not picked up by the impactological media of record such as
CCNet and
BBC Online, let alone given special treatment by the IAU? The
growing list
of removed risks on Sentry does not mention what maximum Palermo
value had
been reached nor any other historical data - an omission, in my
opinion. The
whole issue also forces me to ask again (as I did a few months
back on
CCNet, not receiving one useful reply): What *is* a clear
criterion that
distinguishes a NEA with a high Palermo
value that disappears from the lists within days or weeks from a
really
threatening one whose P value eventually takes off?
Or, put in a more practical way: what pattern of Palermo as f(t)
do we need
to experience in order to raise a real justified alarm with the
public at
large (and ourselves)? It would be great outcome of the NT7 saga
if some
agreement on that could be reached by all official and not so
official
bodies putting out alert messages. And here is a suggestion how
to proceed:
Someone with enough knowledge of the population(s) of NEOs, the
probability
of discovery and the precision of astrometry (and enough
computing power, of
course) should run a really comprehensive Monte Carlo simulation.
Have lots
of NEOs go around the Sun, approach Earth, be discovered by
LINEAR and
friends, be followed-up and sometimes appear on (and in nearly
all cases
disappear again from) Sentry and NEODyS!
Then we could see directly how a typical case of an erroneous
threat (as one
might call 2002 NT7 and kin) develops as compared to a threat
that stays
valid for a long time before vanishing - and compared, of course,
to an actual
impactor. I recall from DPS Meetings in the 90s that simpler
simulations *have* been
done, e.g. by Paul Chodas and Ted Bowell: They were watching how
the
impact probability of a certain impactor would develop with time,
given the
state of the art of astrometry then (and Paul even produced a
pretty scary
movie with the error ellipse slowly closing in on the Earth).
What I am
calling for would be a much more complex simulation, of course -
but it may
be worth the effort.
Regards,
Daniel Fischer
The Cosmic Mirror
www.geocities.com/skyweek/mirror
============
(8) 2002 NT7 IN SOUTH AFRICAN MEDIA
>From Jon Richfield <richfield@telkomsa.net>
Sent: 31 July 2002 16:18
Hi Benny,
FWIW: South African local newspaper reports on 2002 NT7 could
have been
worse.
I saw reports in the English Cape Times, the Afrikaans Die Burger
and a
brief quote in the Mail & Guardian. There were presumably
others, but I am
not much of a news addict, so having dug up those after hearing a
radio
comment about the Cape Times headlines, I left it at that.
The
Cape Times had a front page report from Reuters heavily laced
with your
quotes and explanations, and an explanatory graphic from an
American web
site. Die Burger had briefer (translated) excerpts of the same
report on
page fifteen, and the M&G had about one sentence in a quotes
column. The
tone was generally cheerful and gee-whiz, but as well balanced as
one could
expect from non-technical media.
One or two non-techs asked me to explain it to them and left me
with the
impression that we need never worry about getting directly
through to Mr
Clapham Omnibus. It won't happen. The most important thing then,
is to get
through to the opinion formers, which usually is impossible until
after they have made up their minds.
I have not yet thought through the implications of that. What a
Good Thing
that I am not a pessimist...
Cheers,
Jon
=============
(9) A BIT OF NEO HISTORY: REVERSED ROLES AS BBC CRITCISES NASA
OVER ASTEROID SCARE
>From the BBC News Online, 4 November 2000
http://news.bbc.co.uk/hi/english/sci/tech/default.stm
Warnings of a devastating impact of an asteroid in 2030 were
exaggerated -it
will miss the Earth by millions of kilometres.
By BBC News Online science editor Dr David Whitehouse
Astronomers say reports that the Earth could be struck by a small
asteroid
in 2030 are wildly exaggerated.
Less than a day after sounding the alert about asteroid
2000SG344, a revised
analysis of the space rock's orbit shows it will in fact miss the
Earth by
about five million kilometres (three million miles).
However, astronomers will continue to monitor the asteroid, which
was picked
up in September and thought to be 0.6 km (one mile) across.
Some scientists have criticised the way the information was
released to the
media before it had been thoroughly confirmed.
Threat rating
Asteroid 2000SG344 is the first object to have a threat rating of
greater
than zero on the 0-10 Torino scale of dangerous objects from
space.
It was spotted on 29 September by astronomers David Tholen and
Robert
Whiteley using the Canada-France-Hawaii 3.6-metre telescope on
the island of
Hawaii.
Shortly thereafter, pre-discovery observations taken in May 1999
by the
Linear sky survey were also identified.
On Friday, the International Astronomical Union issued an alert
saying that
the object had about a 1-in-500 chance of striking the Earth on
21
September, 2030.
No object has ever been rated with so high a chance of impact.
Were it to strike our planet, the results would be devastating,
with an
explosion greater than the most powerful nuclear weapon.
Sky survey data
But after the announcement, astronomers began looking at sky
survey data to
see if the object had been picked up but not recognised in
earlier
observations.
This turned out to be the case and these past observations
allowed a more
accurate calculation of the asteroid's orbit to be made.
The result: in 2030, the space rock will miss us by about five
million
kilometres, or 12 times the distance from the Earth to the Moon.
The new orbit reveals a slight risk of a collision with the Earth
about
2071, but it is thought that when the orbit is better known this
risk will
disappear as well.
Currently, asteroid 2000SG344 is about 15 million kilometres
(nine million
miles) away and getting more distant.
'Premature and alarmist'
Because 2000SG344 is in a similar orbit to the Earth, it has been
suggested
that it might be an old Saturn upper-stage rocket of the type
that was used
in the early Apollo Moon missions.
If it is manmade and did strike Earth, the effects would be very
local and
limited.
Some scientists have criticised the IAU and Nasa for releasing
warnings
about the asteroid only for those warnings to be rescinded less
than a day
later.
Benny Peiser of Liverpool John Moores University, UK, said it was
"extremely
unwise, premature and alarmist".
Copyright 2000, BBC
============
(10) AND FINALLY: WHY SMART PEOPLE BELIEVE WEIRD THINGS TOO
Scientific American, September 2002
http://www.sciam.com/article.cfm?articleID=0002F4E6-8CF7-1D49-90FB809EC5880000&pageNumber=2&catID=2
Smart People Believe Weird Things
Rarely does anyone weigh facts before deciding what to believe
By Michael Shermer
In April 1999, when I was on a lecture tour for my book Why
People Believe
Weird Things, the psychologist Robert Sternberg attended my
presentation at
Yale University. His response to the lecture was both
enlightening and
troubling. It is certainly entertaining to hear about other
people's weird
beliefs, Sternberg reflected, because we are confident that we
would never
be so foolish. But why do smart people fall for such things?
Sternberg's
challenge led to a second edition of my book, with a new chapter
expounding
on my answer to his question: Smart people believe weird things
because they
are skilled at defending beliefs they arrived at for nonsmart
reasons.
Rarely do any of us sit down before a table of facts, weigh them
pro and
con, and choose the most logical and rational explanation,
regardless of
what we previously believed. Most of us, most of the time, come
to our
beliefs for a variety of reasons having little to do with
empirical evidence
and logical reasoning. Rather, such variables as genetic
predisposition,
parental predilection, sibling influence, peer pressure,
educational
experience and life impressions all shape the personality
preferences that,
in conjunction with numerous social and cultural influences, lead
us to our
beliefs. We then sort through the body of data and select those
that most
confirm what we already believe, and ignore or rationalize away
those that
do not.
This phenomenon, called the confirmation bias, helps to explain
the findings
published in the National Science Foundation's biennial report
(April 2002)
on the state of science understanding: 30 percent of adult
Americans believe
that UFOs are space vehicles from other civilizations; 60 percent
believe in
ESP; 40 percent think that astrology is scientific; 32 percent
believe in
lucky numbers; 70 percent accept magnetic therapy as scientific;
and 88
percent accept alternative medicine.
Education by itself is no paranormal prophylactic. Although
belief in ESP
decreased from 65 percent among high school graduates to 60
percent among
college graduates, and belief in magnetic therapy dropped from 71
percent
among high school graduates to 55 percent among college
graduates, that
still leaves more than half fully endorsing such claims! And for
embracing
alternative medicine, the percentages actually increase, from 89
percent for
high school grads to 92 percent for college grads.
We can glean a deeper cause of this problem in another statistic:
70 percent
of Americans still do not understand the scientific process,
defined in the
study as comprehending probability, the experimental method and
hypothesis
testing. One solution is more and better science education, as
indicated by
the fact that 53 percent of Americans with a high level of
science education
(nine or more high school and college science/math courses)
understand the
scientific process, compared with 38 percent of those with a
middle-level
science education (six to eight such courses) and 17 percent with
a low
level (five or fewer courses).
The key here is teaching how science works, not just what science
has
discovered. We recently published an article in Skeptic (Vol. 9,
No. 3)
revealing the results of a study that found no correlation
between science
knowledge (facts about the world) and paranormal beliefs. The
authors, W.
Richard Walker, Steven J. Hoekstra and Rodney J. Vogl, concluded:
"Students
that scored well on these [science knowledge] tests were no more
or less
skeptical of pseudoscientific claims than students that scored
very poorly.
Apparently, the students were not able to apply their scientific
knowledge
to evaluate these pseudoscientific claims. We suggest that this
inability
stems in part from the way that science is traditionally
presented to
students: Students are taught what to think but not how to
think."
To attenuate these paranormal belief statistics, we need to teach
that
science is not a database of unconnected factoids but a set of
methods
designed to describe and interpret phenomena, past or present,
aimed at
building a testable body of knowledge open to rejection or
confirmation.
For those lacking a fundamental comprehension of how science
works, the
siren song of pseudoscience becomes too alluring to resist, no
matter how
smart you are.
----------------------------------------------------------------------------
----
Michael Shermer is publisher of Skeptic magazine (www.skeptic.com) and
author of In Darwin's Shadow and Why People Believe Weird Things,
just
reissued.
Copyright 2002, Scientific American
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