PLEASE NOTE:
*
CCNet 117/2001 - 9 November 2001
================================
"Suppose we find with certainty an object heading toward us,
can we,
with the current technology, do anything to avoid the impact?
Unfortunately, the most likely answer to this question, in many
cases, is:
No. Certainly we cannot hope to be able to move a 1-km object if
the
future collision is discovered too late, nor can we hope to solve
the
problem trying to destroy the impactor with nuclear explosives:
celestial
mechanics works differently from ground military operations, and
the
most probable consequence of a desperate, last minute attack
would be to
have many impacts instead of one, with the additional problem of
having
induced some radioactivity on the fragments."
--Andrea Carusi, Tumbling Stone, November 2001
"By the way, all these [deflection] methods were never
tested or
applied for mitigation actions. They were only theoretically
handled.
Besides, as already mentioned, the actual accomplishment of some
of
these mitigation methods seems out of reach even in the distant
future, due to their insurmountable technical problems.
Obviously, the hope
is that we would never need such remedies, but, as the old saying
goes,
hope the best, get ready for the worse!"
--Germano D'Abramo, Tumbling Stone, November 2001
"These star-crossed lovers find themselves strangely
handicapped by
the very intelligence that makes them such remarkable scientists.
Dr.
Swift's star student, Denise, spent her youth absorbed in the
sky,
an escape from the terrors of adolescence, but "her heart
had little room
for anyone. It was too crammed with stars."
--Book review of Andrew Greer's debut novel "The Path of
Small Planets"
(1) ASTEROID DEFLECTION: WE ONLY NEED A LITTLE, GENTLE KICK....
Tumbing Stone, November 2001
(2) EARTH-IMPACTOR MITIGATION METHODS
Tumbing Stone, November 2001
(3) ALL IN THE FAMILITY: SCIENTISTS FIND MOTHER AND DAUGHTER
ASTEROIDS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(4) SLOAN IMPACT RISK SURVEY FALLOUT
(5) DISCOVERY OF BURIED IMPACT CRATERS ON MARS WIDENS POSSIBILITY
OF ANCIENT
MARTIAN OCEAN
Andrew Yee <ayee@nova.astro.utoronto.ca>
(6) GEOLOGICAL MYTH BUSTING: EXTRATERRESTRIALS REALLY DON'T
IMPACT
VOLVANOES?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) ANOTHER SCIENCE MEDIA CENTRE LAUNCHES, BUT WILL IT DELIVER?
Nature Science Update, 8 November 2001
(8) THE PRECAUTIONARY PRINCIPLE: A CRITICAL APPRAISAL OF
ENVIRONMENTAL RISK
ASSESSMENT
CATO Institute, November 2001
(9) THANKS TO THE SLOAN TEAM AND REMEMBER TAMBORA
Andy Smith <astrosafe@yahoo.com>
(10) AND FINALLY: TERRESTRIAL BODIES LOOK TO THE SKY (BOOK
REVIEW)
The Christian Science Monitor, 8
November 2001
===================
(1) ASTEROID DEFLECTION: WE ONLY NEED A LITTLE, GENTLE KICK....
>From Tumbing Stone, November 2001
http://spaceguard.ias.rm.cnr.it/tumblingstone/issues/current/deflect.htm#carusi
by Andrea Carusi (*) - Copyright Tumbling Stone 2001
Discussions about the possibility to divert NEOs in route of
collision with
the Earth have been going on for more than 10 years. The topic is
particularly difficult to address for many reasons. First, there
is a lot of
concern about the means that should be adopted in order to move a
mountain
in an adverse environment such as space; second, it is not clear
at all what
would be the best strategy to achieve the desired goal; third,
although
evereybody agrees that something should be done in case of a
clear threat,
there is considerable debate about the timing, size and
operational details
of a diverting maneuver.
In this number of Tumbling Stone we want to start addressing this
important
issue: in the end, we are searching for NEOs that can collide
with our
planet, and the final goal of our research is either to find that
there is
no relevant danger for the near future (i.e., no sizeable objects
on a
collision course in the next 100 years), or to detect a possible
projectile
and to prepare countermeasures.
The first question that naturally comes to our mind is: suppose
we find with
certainty (I'll come back to what "certainty" may mean)
an object heading
toward us, can we, with the current technology, do anything to
avoid the
impact? Unfortunately, the most likely answer to this question,
in many
cases, is: No. Certainly we cannot hope to be able to move a 1-km
object if
the future collision is discovered too late, nor can we hope to
solve the
problem trying to destroy the impactor with nuclear explosives:
celestial
mechanics works differently from ground military operations, and
the most
probable consequence of a desperate, last minute attack would be
to have
many impacts instead of one, with the additional problem of
having induced
some radioactivity on the fragments. However, this is true for
sizeable
bodies, while small objects could be moved or destroyed much more
easily;
but we are very far, at the moment, from being able to detect a
possible
impactor of any size, down to the Tunguska class.
The "warning time" is therefore a crucial parameter:
this is usually defined
as the time lapse between the discovery of a future impact and
the impact
itself. I will now address this point, showing the importance of
an early
detection.
The path followed by asteroids and comets is dictated by two
major forces,
originated by the solar gravitational pull (dict.) and by the
perturbations
induced by the planets. Other forces, not due to gravitation, are
also
active on relatively long time scales, but they are generally not
relevant
in our context. If there were no planetary perturbations, these
bodies would
move along an ellipse, following Kepler's laws (dict.). This is a
perfectly
predictable situation, provided that the dynamical status of the
object
(i.e., its orbital parameters (dict.)) are known with sufficient
accuracy at
some time. Newton's universal gravitation (dict.), on the other
hand, allows
us to compute the planetary perturbations with high precision, so
that we
can be confident that our predictions will be accurate at least
to the level
of accuracy of the object's orbital parameters. This is a crucial
point
because it affects directly and dramatically our ability to
predict "with
certainty" a future impact.
Suppose that you have an object that will impact Earth at some
time in the
future, and suppose that you know "very well" its
dynamical status. The
question is now: How much should we deviate this object in order
to avoid
the impact? and when? We will see in a moment that "how
much" and "when" are
two corners of the same problem.
The parameters of an orbit are determined by the position of the
object in
space at a given moment and by the size and direction of its
velocity with
respect to a given reference frame. Changing the size and/or
direction of
the velocity vector would result in a change of orbit. This is
what is
normally done to guide spacecrafts: maneuvers in space consist
essentially
in rapid changes to the spacecraft velocity using rocket motors.
There is of
course a direct relationship between the change in velocity (that
is usually
called a "delta V") and the variation of the orbital
parameters. For
instance, an increase of the velocity would translate in an
increase of the
semimajor axis (the mean distance of the object from the Sun)
and, thanks to
Kepler's third law, of the orbital period. This means that, after
the
velocity variation, the object would take a longer time to arrive
at a
specified point of its orbit, for example at the intersection
with the
Earth's path, and this delay would grow with time. Since a delay
in the
timing of the encounter is equivalent to a change of the minimum
distance at
approach, our problem is to investigate what is the delta V to be
provided
to the object so that, after a time lapse corresponding to the
warning time,
the accumulated variation of minimum distance becomes greater
than the
radius of the Earth or, in other words, the impact does not take
place.
This computation has been done at the IAS (Carusi, Valsecchi,
D'Abramo and
Boattini) using numerical integration of the orbital paths in a
variety of
cases. The results confirm the preliminary evaluations made using
very
simple analytical models, but also reveal the existence of
specific
dynamical situations that may be of great relevance for the
solution of this
problem.
Our simulations involved a few fictitious objects, whose orbits
were very
close to the real ones. They have been forced to impact Earth,
and their
path precisely determined in the 50 years preceding impact. We
have then
applied a velocity variation at various moments during this time
span,
searching for the minimum values of the delta V needed to avoid
the
collision at the corresponding times before the anticipated
impact. It is
quite intuitive that an early maneuver would require a smaller
delta V, and
this is what has always been stated, but the shape of the delta V
curve, and
its dependance on the dynamical characteristics of the involved
bodies was
not known until now.
Let me present here only two cases, which are representative of
two
completely different situations. The first refers to the asteroid
1996 JA1,
the second to 1997 XF11. Both are real asteroids, whose orbits
have been
modified in our simulation to obtain an effective collision. The
corresponding delta V curves found with this method are shown in
the figure:
in our simulation they impact Earth in 1996 and 2040,
respectively.
click on the image to see it bigger
http://spaceguard.ias.rm.cnr.it/tumblingstone/issues/current/img/graf.gif
The case of 1996 JA1 is quite smple: at the beginning of the 50
years
interval, in 1946, the delta V needed to miss the Earth 50 years
later is of
the order of 1 mm/s, or even less if the maneuver is applied at
perihelion.
The difference in applying the maneuver at different position
along the
orbit is shown by "waves" in the figure, whose lower
points correspond to
perihelia. The size of this maneuver does not increase very much
with time:
it is still of the order of 1 cm/s only 5 years before the impact
date.
The case of 1997 XF11 is completely different. Here the delta V
needed at
the beginning of the 50 years period, in 1991, is as small as
20-30 microns
per second, and decreases further in the following years, to rise
again
until 2028 when the asteroid encounters the Earth very closely:
this is the
close encounter that has been extensively reported by the press a
few years
ago. Just after this encounter the delta V rises to about 1 cm/s,
a value
very similar to that of 1996 JA1.
The reason for this discrepancy in the two cases must be searched
for in the
phenomenon now known as "resonant return". The
perturbations induced by the
Earth on 1997 XF11 at the encounter in 2028 have put the object
almost
exactly in the 12:7 resonance with the Earth. The consequence of
this event
is that 1997 XF11 impacts Earth exactly 12 years after that
encounter. But
the interesting thing is that, as it is now known, the 2028
encounter acts
as an "amplifier" of the dynamical instability: there
is considerable
difference in applying the delta V just before or just after the
encounter
in 2028, a difference of about a factor of 130. In other words,
when there
is a pre-impact encounter with the Earth, it is much easier to
move the
object before than after that encounter.
This finding, already anticipated by analytical investigations,
is of
extreme importance for our problem. It is true that the objects
exhibiting
resonant returns, such as 1999 AN10 or 1997 XF11, are in
principle more
dangerous, because they encounter the Earth repeatedly for an
extended
period of time, but it is also true that these objects are the
easiest to
deflect, provided that their orbits are known with high accuracy.
This
demonstrates once again how important is the computation of very
accurate
orbits for the most dangerous objects, once they are discovered.
There is another result from the computations done for this
simulation. In
one case the relationships between the shape of the delta V curve
and the
dynamical status are quite complex, being intimately connected to
motion
close to resonances. We are just at the beginning of the
exploration of this
important dynamical behaviour, and any discussion on deflection
of incoming
objects must take into account that the timing and size of
deflection
maneuvers must be studied with great care, after having
investigated in
detail the possible dynamical evolution of the object.
Finally, one could use these results to analyse the relative
merits of
various deflection techniques. An object of 1 km radius with a
density of
2-3 g/cm^3, has a mass of about 10^15 g. If we want to accelerate
it by 10
microns per second, it is sufficient to use kinetic energy
because the
collision of a 5 tons projectile at 2 km/s of relative speed
would do the
job. 5 tons is the weight of the Cassini spacecraft at launch.
Furthermore,
we have studied only impulsive maneuvers, while for such small
delta V's it
could perhaps be more convenient the use of more exhotic methods
such as
solar sails or mass drivers. In any case, it is clear that an
early
intervention would definitely resolve all problems related to the
possible
use of nuclear devices.
Andrea Carusi (*) - president of the Spaceguard Foundation
Copyright Tumbling Stone 2001
=============
(2) EARTH-IMPACTOR MITIGATION METHODS
>From Tumbing Stone, November 2001
http://spaceguard.ias.rm.cnr.it/tumblingstone/issues/current/dabramo.htm
by Germano D'Abramo (*) - copyright TumblingStone 2001
The need to avoid the impact of an asteroid with the Earth has
led to what
is now known as mitigation strategy. There are two basically
different
approaches to the problem: the change of the asteroid's orbit
(deflection)
or the asteroid fragmentation and its dispersal.
The fragmentation procedure appears to be risky and in some cases
even
impossible for at least two reasons:
* it would require huge amounts of nuclear explosive to be put in
orbit and
this cannot be done without some risk for the Earth environment.
* given our current knowledge, it is very difficult to predict
the right
amount of energy required to completely fragment and disperse the
asteroid,
and even if we succeed in this * operation we cannot exclude that
the great
bulk of the asteroid's fragments falls on the Earth anyway (see
actual issue
of T.S. "We only need a little, gentle kick ..." by
Andrea Carusi.
Moreover, the fragmentation procedure is impossible in some
cases, for
example:
* the asteroid is too big for the available nuclear explosive
here on the
Earth (it is estimated that in order to fragment an asteroid 0.1,
1.0 and 10
km wide nuclear charges are necessary with energies of the order
of some Kt,
Mt and Gt (dict.), respectively!).
* in order to produce optimum fragmentation, the charge should be
buried in
the asteroid, with obvious (currently insuperable) technical
difficulties.
Can a nuclear explosion be used to deflect an impactor?
Concerning the deflection procedure, it suffices to aptly modify
the orbital
velocity of the impacting body along its revolution around the
Sun. For the
sake of simplicity, we could say that the velocity change must
lead the
asteroid gain ground (or lose it, depending on if we increment or
decrement
its orbital velocity) with respect to the motion of the Earth
during the
time span between the application and the predicted epoch of
collision of an
amount of at least one Earth radius. Therefore, it is clear that
the longer
the warning time before the epoch of the impact, the less the
magnitude of
the velocity change required for the same deflection. Namely, in
most cases
it is exactly an inverse proportion between warning time and
magnitude of
velocity change, if we obviously ignore such peculiar cases like
that
described by A. Carusi in this issue of T.S.
The velocity change can be impulsive or steady. It is impulsive
if it is
delivered "instantaneously'', in one solution. The velocity
change is steady
when a constant thrust is applied to the asteroid for a longer
time span,
which could be even equal to the warning time before the impact.
Within the known mitigation strategies there are the following
impulsive
methods:
Impactors: namely, space probes or specially designed projectiles
which will
hit the asteroid at high velocity, spall off asteroid material,
and will
therefore deliver an impulse (momentum dict.) able to change the
asteroid
orbit (see the example of "We only need a gentle, little
kick")
Asteroid-Asteroid collisions: this method consists in changing
the orbit of
a small harmless asteroid so that it will collide with a larger
asteroid on
collision course with the Earth and change its orbit.
Nuclear explosives: nuclear explosions could be used in two
different ways:
(1) as a stand-off explosion at some distance from the asteroid
surface; the
flash produced by the explosion vaporises the exposed side of the
asteroid.
The surface material will therefore instantaneously spall away
delivering an
impulse to the rest of the asteroid (see image above). (2) as an
explosion
directly on the asteroid surface; such explosion excavates a huge
crater and
ejects its material away from the asteroid. In this case, the
deflecting
impulse is provided by the recoil from the ejected mass. As for
the
fragmentation and dispersal strategies, some perplexities arise
in these
cases: such ``energetic'' approaches to deflection seem to be
very risky
because they are not so much controllable.
Among the steady mitigation methods there are:
Chemical, electric or nuclear propulsion: conventional chemical
propulsion
system, electrical or nuclear fission engines could be attached
to the
asteroids and fired when the thrust vector points to the desired
direction
(due to the asteroid's own rotation).
Laser systems: in this case the asteroid surface is irradiated by
an high
energy laser beam (ground-based or space-based). This beam would
vaporise
surface material which will stream away from the asteroid
producing thrust.
Mass drivers: mass drivers are devices which has to be installed
on the
asteroid surface. They excavate and accelerate away from the
asteroid
gravitational field small mass packages. The recoil produced by
this
expulsion provides the thrust required to deflect the asteroid
from its
pristine orbit.
Non-gravitational forces: this method consists, for instance, in
covering
the asteroid surface partially or completely with some
high-reflectivity
material (e.g. white powder, see T.S. number 5: "The sweet
solution" by
Andrea Milani). This material would enhance the thrust given by
the solar
radiation on the asteroid surface. Nevertheless, the
effectiveness of this
approach is rather scanty, even with very small asteroids (e.g.
of the order
of 10 meters), and pretty long warning times are needed to reach
a sensible
deflection.
Mirrors and solar sails: for what concern solar mirrors, they
essentially
act like laser system. A suitable mirror, orbiting around the
asteroid,
collects solar radiation and focuses it onto the asteroid
surface. This high
energy concentration vaporises the surface material creating a
thrusting
stream. A different way to take advantage of solar radiation is
to create
huge mirror sails and to attach them to the asteroid. In this
case, the
thrust needed for deflection is provided by the solar light
pressure. It is
pretty clear that this strategy suffers, more than others, from
many
technical problems; for example, the sail area has to be at least
in the
order of many square kilometers to provide a sensible thrust.
Solar panels, a mean of deflection?
By the way, all these methods were never tested or applied for
mitigation
actions. They were only theoretically handled. Besides, as
already
mentioned, the actual accomplishment of some of these mitigation
methods
seems out of reach even in the distant future, due to their
insurmountable
technical problems. Obviously, the hope is that we would never
need such
remedies, but, as the old saying goes, hope the best, get ready
for the
worse!
Copyright Tumbling Stone 2001
==========
(3) ALL IN THE FAMILITY: SCIENTISTS FIND MOTHER AND DAUGHTER
ASTEROIDS
>From Andrew Yee <ayee@nova.astro.utoronto.ca>
Geological Society of America
Boulder, Colorado
Contact:
Ann Cairns, Director-Communications and Marketing
acairns@geosociety.org,
303-357-1056
Written by Kara LeBeau, GSA Staff Writer
FOR IMMEDIATE RELEASE: November 8, 2001
GSA Release No. 01-59
All in the Family: Scientists Find Mother and Daughter Asteroids
There are asteroids and there are asteroids. Most were once part
of larger
"parent bodies" and some supply meteorites that plunge
to Earth.
But how do you trace the family line of asteroids? Scientists
compare
mineralogy of asteroids by analyzing their near-infrared spectra.
They also
compare asteroids' orbits around the sun. And recently they found
a perfect
match -- "uniting" in a scientific sense, mother and
daughter asteroids.
"We determined the mineralogy of asteroid 1929 Kollaa and
found that it was
once part of a larger asteroid called 4 Vesta. I was inspired to
observe
these objects because they belong to the rare V-class of
asteroids, and they
have orbits about the Sun that are very similar," explained
Michael Kelley
from NASA's Johnson Space Center. "Vesta is the asteroid for
which the
V-class was established. Until now, no mineralogical analysis had
ever been
done on another V-type. In that sense, Vesta was unique until our
recent
work was done. We found not only that this second V-class
asteroid, 1929
Kollaa, was once part of Vesta, but that it is also related to a
very
specific group of meteorites."
Kelley will present this new discovery on Thursday, November 8,
at the
Geological Society of America's annual meeting in Boston.
Most planetary scientists believe that 4 Vesta is the source of
howardite,
eucrite, and diogenite meteorites (HED) found on Earth, but
Kelley points
out that it is not a direct process. "Vesta is located in a
part of the main
asteroid belt that makes it almost impossible for it to deliver
meteorites
directly to Earth. So there are probably intermediate asteroids,
which were
once part of Vesta, located in more favorable orbits that provide
delivery."
One of the ramifications of this discovery is that it will help
scientists
build a geologic map of the asteroid belt and understand what
forces have
acted on asteroids in the past. This information, along with
asteroids'
mineralogy, would be crucial if there was ever a need to prevent
an asteroid
from striking the Earth and causing a major disaster.
CONTACT INFORMATION
During the GSA Annual Meeting, November 4-8, contact Ann Cairns
or Christa
Stratton at the GSA Newsroom in the Hynes Convention Center,
Boston,
Massachusetts, for assistance and to arrange for interviews:
(617) 954-3214.
The abstract for this presentation is available at:
http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_20247.htm
Post-meeting contact information:
Michael S. Kelley
NASA Johnson Space Center
Code SR
2101 NASA Rd. 1
Houston, TX 77058
E-mail: michael.kelley1@jsc.nasa.gov
Phone: 281-244-5119
Fax: 281-483-1573
Ann Cairns
Director of Communications
Geological Society of America
Phone: 303-357-1056
Fax: 303-357-1074
E-mail: acairns@geosociety.org
===========
(4) SLOAN IMPACT RISK SURVEY FALLOUT
--STUDY LOWERS LIKELIHOOD OF ASTEROID HIT
CNN, 8 November 2001
http://www.cnn.com/2001/TECH/space/11/08/asteroids.report.reut/index.html
--SURVEY LOWERS IMPACT RISK
BBC Online News, 8 November 2001
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1644000/1644899.stm
--LESS REASON TO FEAR
ABC News, 8 November 2001
http://abcnews.go.com/sections/scitech/DailyNews/asteroidrisk011108.html
--KILLER ASTEROIDS MORE SCARCE THAN THOUGHT
New Scientist, 8 November 2001
http://www.newscientist.com/news/news.jsp?id=ns99991545
--ODDS OF EARTH BEING HIT BY BIG ASTEROID LOWERED
Houston Chronicle, 8 November 2001
http://www.chron.com/cs/CDA/story.hts/space/1124076
===============
(5) DISCOVERY OF BURIED IMPACT CRATERS ON MARS WIDENS POSSIBILITY
OF ANCIENT
MARTIAN OCEAN
>From Andrew Yee <ayee@nova.astro.utoronto.ca>
Geological Society of America
Boulder, Colorado
Contact:
Ann Cairns, Director-Communications and Marketing
acairns@geosociety.org,
303-357-1056
Written by Kara LeBeau, GSA Staff Writer
FOR IMMEDIATE RELEASE: November 8, 2001
GSA Release No. 01-56
Discovery of Buried Impact Craters on Mars Widens Possibility of
an
Ancient Martian Ocean
Soon after Mars was formed, it was bombarded by numerous large
meteorites
and asteroids. Scientists have discovered an unexpectedly large
grouping of
impact basins buried under Mars' northern plains that resulted
from this
pounding. They used Mars Orbiter Laser Altimeter (MOLA)
topographic data to
find them, because they can't be seen in images of the Martian
surface.
Above these basins are thin young plains, but the lowland crust
beneath them
is actually extremely old and was formed very, very early.
According to
Herbert Frey of the Geodynamics Branch of NASA's Goddard Space
Flight
Center, this is a radical departure from the popular
belief that the northern lowlands were formed later in Martian
history,
perhaps by plate tectonic style processes.
Frey will discuss these findings on Thursday, November 8, at the
Geological
Society of America's annual meeting in Boston, Massachusetts.
This discovery is a crucial piece to one of the greatest unsolved
puzzles
about Mars-why does its surface have two distinct hemispheres:
one that is
high and heavily cratered and one that is low and sparsely
cratered? The
origin of this fundamental "crustal dichotomy" is
uncertain both in terms of
how and when it formed. But this recent discovery of the numerous
buried
craters may pin down the answer to when the lowlands first
formed.
"The ancient age of the lowlands means whatever process
produced them
occurred both early and relatively quickly," explained Frey.
"Things like
plate tectonics may not work. Another ramification is that there
have been
lowlands in the northern parts of Mars for essentially all of
Martian
history. That means that at whatever early time conditions
permitted liquid
water to exist on Mars, there was a northern lowland into which
that water
could drain. So it is quite possible that a shallow ocean may
have existed
on Mars very early in its history, as some have suggested based
on
completely different data."
"The origin of the crustal dichotomy on Mars has been one of
the main areas
of my own research for a long time, so anything that could tell
us how old
the lowlands really were naturally was of interest," Frey
said. "And of
course, the discovery aspects of 'seeing' (in elevation data)
things that no
one else had ever seen or even guessed might be there is
intrinsically
intoxicating. Not only has this work turned out to be very
important, but
it's also been fun!"
CONTACT INFORMATION
During the GSA Annual Meeting, November 4-8, contact Ann Cairns
or Christa
Stratton at the GSA Newsroom in the Hynes Convention Center,
Boston,
Massachusetts, for assistance and to arrange for interviews:
(617) 954-3214.
The abstract for this presentation is available at:
http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_25358.htm
Post-meeting contact information:
Herbert Frey
Geodynamics Branch
Goddard Space Flight Center
Code 921
Greenbelt, MD 20771,
E-Mail: frey@core2.gsfc.nasa.gov
Phone: 301-614-6468
Fax: 301-614-6522
Ann Cairns
Director of Communications
Geological Society of America
Phone: 303-357-1056
Fax: 303-357-1074
E-mail: acairns@geosociety.org
===============
(6) GEOLOGICAL MYTH BUSTING: EXTRATERRESTRIALS REALLY DON'T
IMPACT
VOLVANOES?
>From Andrew Yee <ayee@nova.astro.utoronto.ca>
Geological Society of America
Boulder, Colorado
Contact:
Ann Cairns, Director-Communications and Marketing
acairns@geosociety.org,
303-357-1056
Written by Kara LeBeau, GSA Staff Writer
FOR IMMEDIATE RELEASE: November 8, 2001
GSA Release No. 01-52
Geological Myth Busting: Extraterrestrials Really Don't Impact
Volcanoes?
The idea that volcanoes can erupt when the Earth is smacked by a
large comet
or meteorite has become a popular idea in geology. But one
challenger of
this idea says there's no proof to back it up.
"Not only is there not any firm evidence that an impact
started a volcanic
eruption on Earth or on any other planet, there is no known
mechanism by
which this can occur," explained Jay Melosh, professor of
Planetary Sciences
at the University of Arizona. Melosh will present new research
that
substantiates his case against this widely-held idea on Thursday,
November
8, at the Geological Society of America's annual meeting, A
Geo-Odyssey, in
Boston, Massachusetts.
"I will offer both evidence of the lack of impact-induced
volcanism on other
heavily-impacted planets in our solar system and a theoretical
analysis of
the conditions created by a large impact on Earth," he said.
"This is new
research based on both observational studies of planetary images
and
theoretical studies of the conditions surrounding an impact
crater. It does
build on previous efforts by a number of researchers."
CONTACT INFORMATION
During the GSA Annual Meeting, November 4-8, contact Ann Cairns
or Christa
Stratton at the GSA Newsroom in the Hynes Convention Center,
Boston,
Massachusetts, for assistance and to arrange for interviews:
(617) 954-3214.
The abstract for this presentation is available at:
http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_28367.htm
Post-meeting contact information:
Jay Melosh
Lunar and Planetary Lab-West
University of Arizona
Tucson AZ 85721 USA
E-mail: jmelosh@lpl.arizona.edu
Phone: (520) 621-2806
Ann Cairns
Director of Communications
Geological Society of America
Phone: 303-357-1056
Fax: 303-357-1074
E-mail: acairns@geosociety.org
==============
(7) ANOTHER SCIENCE MEDIA CENTRE LAUNCHES, BUT WILL IT DELIVER?
>From Nature Science Update, 8 November 2001
http://www.nature.com/nsu/011108/011108-13.html
London hub hopes to nurture science-media affairs.
HELEN PEARSON
Science journalists are being seduced in a new London club. The
Science
Media Centre, which opens today, has ambitious plans to improve
science news
coverage. But sceptics are concerned that the centre may benefit
scientists
and the press more than the public.
Recent media controversies over health risks from genetically
modified crops
and bovine spongiform encephalopathy (BSE) have left many
researchers
peeved. They feel that more rapid, accurate communication of
scientific data
and opinion might have allayed public fears.
"We are here to act as a portal," says Susan
Greenfield, director of UK
academic society the Royal Institution, which is launching the
£120,000
(US$175,000) centre. The centre hopes to become journalists'
first call for
scientific contacts and information. It plans to provide rapid
and sound
scientific response to breaking news through a database of
experts or by
speaking on behalf of shy scientists.
Science communicators have long agreed that an informed public
needs
researchers to open up to reporters. The very nature of research
- giving
considered, informed judgement - is often incompatible with the
quick
comment needed to meet press deadlines. "What they all fear
is getting the
facts wrong," admits Greenfield.
Precisely how the centre will persuade reticent researchers to
start giving
off-the-cuff comments is unclear, says Diane Stilwell,
public-affairs
manager of the Institute of Physics, a learned society in London.
"If
science and scientists want to be in the mainstream news they
have to learn
to play by the news-gathering rules," she says. "We
can't demand special
treatment."
How the media stand to gain from the centre is also vague.
"It's not clear
to me that there's a demand," says Peter Briggs, chief
executive of the
British Association for the Advancement of Science (BA), the UK's
science-communication organization. The BA and their US
counterpart the
American Association for the Advancement of Science already offer
databases
of experts as part of their online science press sites,
AlphaGalileo and
Eurekalert!.
The US Media Resource Centre, a freephone referral service
between
journalists and scientists, has been running since 1980.
First-time
reporters are the ones who call, says co-ordinator Martin Baucom.
Science
journalists, who mostly have their own contacts, only use them
"once in a
while when they're really stumped".
Whether the media were sufficiently consulted before the launch
has been
questioned. Discussion is a must to improve science coverage,
thinks Briggs.
The ultimate aim would be to attain front-page stories from
science
reporters and more scientifically informed stories from political
ones, but
he says that "the age of pontification is over ... we should
be sitting down
and talking with [the media]".
All things to all people
Greenfield's current plans for the centre are broad and ambitious
for an
initial staff of three. "We want to be all things to all
people," she says.
For the non-specialist media, the centre aims to explain
scientific jargon
and methodology, such as control groups, statistical tests and
peer review -
whether in person, print or online is not yet clear. For the
scientifically
literate, they plan to build up interviews and surveys in
anticipation of
newsworthy issues. "I'd like to get away from always being
on the back
foot," she says.
Most agree it is a laudable first step towards improving the
accuracy of
science news
The centre's goal to be an independent source of information
without opinion
may be at odds with its parallel aims to be pro-active in
releasing science
stories and raising awareness of science. The newly appointed
head of the
centre, Fiona Fox, has a background in media relations; the hard
science is
being left to the deputy head.
With broadcast facilities and plans for a restaurant and bar, the
centre
also hopes to become a venue for science press conferences,
broadcasts and
meetings - even a place to have coffee and "hang out",
says Greenfield,
"like a science Groucho club".
Whether it becomes more than a scientist's clubroom only time
will tell.
Most agree that it is a laudable first step towards improving the
accuracy
of science news and that its role will evolve with time.
Opened on Wednesday evening by Cherie Booth, QC, the centre will
begin
business in early 2002. Running costs of £200,000 a year for
three years are
being sought from private and public sources, with each donation
capped at
5% of the total to maintain independence.
© Nature News Service / Macmillan Magazines Ltd 2001
=============
(8) THE PRECAUTIONARY PRINCIPLE: A CRITICAL APPRAISAL OF
ENVIRONMENTAL RISK
ASSESSMENT
>From CATO Institute, November 2001
http://www.cato.org/cgi-bin/Web_store/web_store.cgi?page=precprinciple.html&cart_id
by Indur M. Goklany
The "precautionary principle"-the environmental version
of the admonition
first, do no harm-is now enshrined in numerous international
environmental
agreements including treaties addressing global warming,
biological
diversity, and various pollutants. Some environmentalists have
invoked this
principle to justify policies to control, if not ban, any
technology that
cannot be proven to cause no harm. In this innovative book,
Goklany shows
that the current use of the precautionary principle to justify
such policies
is flawed and could be counterproductive because it ignores the
possible
calamities those very policies might simultaneously create or
prolong.
The precautionary principle, unfortunately, does not provide any
method of
resolving such dilemmas, which are commonplace in the field of
environmental
policy. To address that problem, Goklany develops a framework
consistent
with the precautionary principle to resolve such dilemmas. That
framework
ranks potential threats to the environment on the basis of their
nature,
magnitude, immediacy, uncertainty, persistence, and the extent to
which they
can be alleviated.
Applying that framework to three contentious environmental policy
issues
facing humanity and the globe-DDT, bioengineered crops, and
global
warming-Goklany shows that some popular policy prescriptions,
despite good
intentions, are in fact likely to do more harm than good.
============================
* LETTERS TO THE MODERATOR *
============================
(9) THANKS TO THE SLOAN TEAM AND REMEMBER TAMBORA
>From Andy Smith <astrosafe@yahoo.com>
Hello Benny and CCNet,
Recognizing the pressing need to get larger telescopes involved
in the hunt
for that one rock (with our name on it), which is still headed
this way; it
was delightful to read the reports from the members of the Sloan
Digital Sky
Survey (SDSS) team.
We continue to urge the large telescopes to take a more active
roll in the
NEO hunt, while we still have the time....and no one would have
been more
interested in seeing the Sloan telescope being used to help save
the human
race, than Alfred P. Sloan, Jr. He was a gifted manager and
electrical
engineer, who was the President of the General Motors
Corporation, in 1934,
when he established his Foundation. He once said that,
"Bedside manner is no
substitute for a good diagnosis" and he clearly favored
getting important
data, as quickly as possible....especially when millions of lives
are at
stake.
Global Disaster Threshold
Both Michael Paine and I have concluded that a Tambora-class
terrestrial
explosion (1,000 megaton range) could cause a global disaster and
that an impact
in the 200-300 meter range (mag 22-21) could provide this level
of destructive energy.
The Tambora volcanic explosion, in 1815, produced the
year-without-a-summer
(1816). There were millions of fatalities and most resulted from
starvation.
The global disaster threshold is clearly much lower (or smaller)
than
1km....probably in the 200-300 meter range (ACE#3-4).
Early Efforts
Many of us watched, during the 1990's, as a few of our courageous
colleagues
built and operated the first asteroid early-warning
telescopes.....starting
with film cameras and converting to CCD. We know that much of
their support
was from volunteers and contributions and we greatly appreciate
their
efforts.
However, with the lessons of the 90's behind us, it is now time
to squarely
face the threat from the sky and to recognize that more than 95%
of the
really dangerous NEO are smaller than a kilometer wide. We need
to do all we
can to get larger telescopes and CCD cameras involved in the hunt
and to
aggressively seek-out those tens-of-thousands of sub-kilometer
NEO.
We need all of the excellent teams, who are now involved, as well
as help
from the larger telescopes, which should report every sighting to
one of the
teams. It is clear that they see asteroids all-the-time. It is
also clear
that any one of those could be the one we are looking for....the
one with
our name on it.
We are especially happy to see the development of the
Liverpool-JMU-Bisei-Faulkes team and we are hoping that this
group will be
able to report all sightings to Dr. Isobe and his team, for
further study
and the appropriate reporting to the MPC.
Tumbling Stone
The current issue of the Tumbling Stone, which is provided to the
Web by the
Spaceguard Foundation and the NEO Dynamic Site (University of
Pisa), is
especially interesting. It is Issue 9:01/11/2001. See
http://spaceguard.ias.rm.cnr.it/tumblingstone/
In this issue, Andrea Causi, Germano D'Abramo, Andrea Milani and
others
discuss NEO impact mitigation. We want to see Spaceguard address
this
important matter and join with the Space Shield Foundation, the
UN, the
AIAA, NASA, the ESA and the space and defense agencies of many
countries, to
mount an effective global emergency preparedness program. We are
also
encouraging the companies planning for space mining and tourism,
to include
NEO emergency preparedness in their planning, since, until we
have a
planetary defense system, they may be in the best position to
respond
quickly.
Cheers
Andy Smith
============
(10) AND FINALLY: TERRESTRIAL BODIES LOOK TO THE SKY (BOOK
REVIEW)
>From The Christian Science Monitor, 8 November 2001
http://www.csmonitor.com/2001/1108/p20s2-bogn.html
The cycles of a new comet provide the structure for this debut
novel
By Ron Charles
For an astronomer, describing a single body in motion is simple.
And
calculating the interaction of two objects is as easy as pi. But
300 years
after Sir Isaac Newton's equations on gravity, the interaction of
three
bodies still baffles the best mathematicians.
For problems like that, call a novelist. They've been writing
about the
interaction of bodies since the apple bonked Newton.
Perhaps none has blended the worlds of astronomy and romance so
stunningly
as Andrew Greer. His debut novel, "The Path of Small
Planets," traces the
lives of several scientists connected with a newly discovered
comet.
We meet them in 1965, when Dr. Swift and his colleagues and
graduate
students gather on a small island in the South Pacific to view
his comet and
its attendant meteor shower. The warm air is thick with
mosquitoes and
egotism. The scientists smirk at the natives and their primitive
anxiety
about omens streaking across the sky.
Just as the first sparks appear above them, a young boy falls
from the
observation deck to his death. For these students of physics, the
accident
is an equation with brutal implications: "They were
scientists," Greer
writes, "and could turn life into a laboratory setting,
control every aspect
so that it pointed toward an answer. A crowd of artists, of
dancers, of
poets could never have blamed themselves for terrible chance, but
these
scientists thought they held chance firmly in their grip."
This inexplicable tragedy alters the trajectory of their lives in
ways none
of them could predict. Greer's strategy for observing these
changes is to
visit the scientists and their loved ones every six years, as
they continue
to gather to celebrate the comet's appearance.
Survivors of "Same Time Next Year," take heart: In
Greer's hands, this
periodic form seems entirely natural, even cosmic, placing us in
the
position of that frozen ball of dust that races by the blue
planet. Each
pass offers another sighting of brilliant people baffled by the
calculus of
romance.
These star-crossed lovers find themselves strangely handicapped
by the very
intelligence that makes them such remarkable scientists. Dr.
Swift's star
student, Denise, spent her youth absorbed in the sky, an escape
from the
terrors of adolescence, but "her heart had little room for
anyone," Greer
writes. "It was too crammed with stars."
Now, at 25, she finds herself prone to the foolish,
self-destructive
passions she should have worked out in her teens. "What
could her life have
been?" she wonders. "Dances, coy looks, unwanted
advances? Instead of
stars?"
Impulsively, she marries a pleasant but pedestrian novelist who
can't share
her celestial interests or succeed in his own sphere. The person
she truly
loves is Eli, her best friend's husband, a fellow astronomer who
suffered
the same truncated childhood and accelerated maturity in the
pursuit of
intellectual development.
Eventually, Denise and Eli have an affair under the guise of
discovering
their own comet, but what they really discover is that a
relationship
involving the betrayal of people who love them brings no lasting
satisfaction. The book's most moving passages follow the faint
breezes of
resentment and loneliness that blow through a good marriage.
As the years pass, Greer moves on to the children of these
scientists, young
people strangely wounded by the thin atmosphere of affection in
their
scientific homes. Dr. Swift's daughter lives between the fear
that she isn't
sufficiently intellectual and the dread of becoming like her
father's nerdy
colleagues. Denise's son, like all the faculty children, must
compete with
the stars.
Greer attracted critical praise last year for his first
collection of short
stories, "How It Was For Me." This first novel displays
the same startlingly
clever phrasing and a careful sensitivity with a wide range of
characters -
young and old, male and female, scientists and their artistic
spouses.
Despite his remarkably wise insight into the nature of marriage
and
friendship, there's a certain chilliness to his portrayal that
reminds us
that we're always looking at these characters through a
microscope. His own
voice, polished to such luminescence, remains the most passionate
object in
this haunting universe.
Copyright 2001, The Christian Science Monitor
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