PLEASE NOTE:
*
CCNet DIGEST, 5 May 1998
------------------------
(1) NEWS OF NASA EFFORT
Ed Grondine <epgrondine@hotmail.com>
(2) NEW FILMS: DEEP IMPACT AND ARMAGEDDON
David Morrison <david.morrison@arc.nasa.gov>
(3) 'MINI' ALIEN INVASION HITS THE EARTH
Roger Highfield, Science Editor, The Daily
Telegraph
(4) METEOR SHOWER THREAT?
John Wagoner <stargate@gte.net>, SKY
& TELESCOPE'S NEWS BULLETIN
(5) CALIBAN & SYCORAX: NEW NAMES FOR ICY MOONS OF URANUS
Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
(6) ASTEROID MAKES WAVES, ASTRONOMERS COMPUTE ...?
P. Daukantas, COMPUTERS IN PHYSICS
(7) STEPHEN J GOULD ON GULLIVER'S FURTHER TRAVELS
S.G. Gould, Harvard University
=========================
(1) NEWS OF NASA EFFORT
From Ed Grondine <epgrondine@hotmail.com>
Benny -
I got up at 3:30 this morning and drove up to DC for the
"Global Air &
Space 98" meeting held by the American Institute of
Aeronautics and
Astronautics. I spoke with Richard Christiansen, Acting NASA
Associate
Administrator for Aero and Space Technology, who told me the
following:
NASA is setting up a program office to deal with the
problem of
potential Earth impactors, and Dan Goldin briefly mentioned this
in his
presentation to Congress a few weeks back.
The effort is currently under the direction of Dr. Wesley
Huntress. A
location for the program office has not yet been selected, though
Houston (I guess the Lunar and Planetary Institute) is under
consideration.
The program is intially to serve as a focus point for currently
existing NASA projects in this area, and NASA is undertaking an
evalutation of the threat posed by Earth impactors before
deciding how
much will have to be done.
NASA is also aware that it will be unable to handle this problem
by
itself and that they will have to coordinate with the programs of
other
countries.
If I got all of this straight, this is certainly some good news.
Let's
hope that NASA gets the real experts' estimates to make its
evalutaion
of the threat.
Your tired correspondent,
Ed
E.P. Grondine
================================
(2) NEW FILMS: DEEP IMPACT AND ARMAGEDDON
From David Morrison <david.morrison@arc.nasa.gov>
Two major Hollywood productions dealing with the asteroid and
comet
impact danger are being released in 1998: Deep Impact (a
Spielberg/Dreamworld Production) on May 8 and Armageddon (Disney
Films)
on July 1. These films may do more to publicize the impact hazard
than
all previous media coverage taken together. But are the
films
technically credible, and what effect will they have on public
attitudes toward asteroid and comet impacts?
Deep Impact (Dreamworks and Paramount Pictures) is directed by
Mimi
Leder and stars Robert Duvall, Tea Leoni, Elijah Wood, Vanessa
Redgrave, and Morgan Freeman. The Executive Producers are Steven
Spielberg, Joan Bradshaw and Walter Parkes. Listed as scientific
advisors are Carolyn and Gene Shoemaker, Chris Luchini, Joshua
Colwell,
Gerry Griffin, and David Walker, and the original idea is from
the
novel Hammer of God by Arthur C. Clarke. The story line concerns
a
comet a few miles in diameter that is headed for the Earth. Much
of the
plot is about what people would consider most important if they
knew
that they only had a few months to live, reminiscent of the
classic
science fiction film When Worlds Collide. While the planet
prepares for
disaster, astronauts try to use nuclear explosives to deflect the
comet, but they succeed only in breaking it into two pieces, one
of
which (2 km in diameter) strikes in the Atlantic ocean and wipes
out
coastal cities by a spectacular tsunami that engulfs the entire
US
eastern seaboard. The larger fragment is deflected at the last
minute
by a heroic and suicidal effort, so the rest of the planet is
spared.
Technically, Deep Impact is reasonably accurate. The idea of a
comet
being spotted about 2 years before impact is plausible, and the
strategy to deflect it with nuclear explosives is also
appropriate. The
special effects on the surface of the active comet are realistic,
as is
the tsunami produced when the smaller fragment hits the Atlantic.
The
film makes no mention of other environmental effects of a 2-km
ocean
impact, but it correctly anticipates the extremely serious
consequences
of the larger impact (what they call an ELE or extinction-level
event).
The idea of a nuclear-powered spacecraft to take astronauts to
the
comet is fiction, of course, at least in terms of current
technology,
but the film gets high marks for understanding the nature of the
impact
threat and for the quality of its special effects imagery.
Armageddon, staring Bruce Willis and produced by Jerry
Bruckheimer for
Disney, is quite another story, and one suspects that it was
never
concerned about technical accuracy -- perhaps more of a spoof
like
Independence Day or Men in Black. No one from the comet/asteroid
community was consulted, and the only technical advice that is
credited
is from former NASA employees Joe Allen and Ivan Beckey. In this
case
the threatening NEO is an asteroid "the size of Texas",
which is about
a million times larger (in mass and energy) than any
Earth-crossing
asteroid, but the warning time is just a few weeks. Instead of
entrusting planetary defense to trained astronauts or the
military, a
bunch of amateurs is recruited, given a week of training, and
blasted
off in two Space Shuttles to intercept the asteroid. Apparently
no one
told the producers that the Shuttle is limited to low Earth
orbits. The
job of the astronauts is to drill down about 200 m and plant
nuclear
explosives. Unlike the sets of Deep Impact that try to
portray the
surface of a comet accurately, the asteroid set for Armageddon
does not
look at all like an asteroid, and strangely the hole they drill
glows
orange as if there were magma just below the surface. The world
may be
saved in Armageddon, but the credibility of the movie is a
casualty.
These are the fourth and fifth movies respectively made about the
impact hazard, so further comparisons are in order. First came
the 1979
Hollywood film Meteor, staring Sean Connery and Natalie Wood, in
which
a joint US/USSR effort is made to intercept the incoming asteroid
and
disrupt it with nuclear explosives. The major tragedy is thus
averted,
although several smaller hits demonstrate the destructive power
of
impacts (especially one that strikes in Central Park, New York
City).
The initial premise of the film, with an asteroid knocked out of
the
main belt and into the Earth's path, is ridiculous, but most of
the
rest of the film is reasonably plausible, and it makes for a good
cold-war era thriller. Meteor was not well received at the time,
however, in part because reviewers did not take the impact
possibility
seriously. The next film was Fire from the Sky, made for
television in
the late 1980s. Here a comet takes out Phoenix, Arizona. There is
no
attempt to intercept the comet, and most of the drama concerns
issues
of when to warn the populace and (given that the warning was
delayed
till the last minute) how to evacuate Phoenix in time. Third was
the
1997 TV "miniseries" Asteroid, which ran for more than
3 hours but was
later released on videotape in a 2-hour version. As in Meteor,
the film
starts implausibly with a comet diverting a main-belt asteroid
into a
collision course. This time the target is Dallas, Texas, with a
smaller
impact near Kansas City. The special effects are weak, the
efforts to
stop the incoming asteroid with airborne radar are ludicrous, and
after
the impact the film settles into a generic disaster format, with
people
trapped in collapsed buildings, lost children, and the like. The
only
good thing one could say about this film is that everyone works
together to deal with the disaster; there are no dumb subplots or
human
villains.
These five films can be ranked according to their realism and
technical
accuracy in portraying the threat of a cosmic impact. From
best to
worst, they are Deep Impact, Fire from the Sky, Meteor, Asteroid,
and
Armageddon. But whatever their technical strengths or weaknesses,
they
should sensitize the public to the existence of an impact danger,
and
perhaps also to the fact that we could mount a defense against an
incoming object and thus avert the disaster entirely. One would
not
expect the defenses to be entirely successful in a movie, because
that
would mean no spectacular visual impact effects, but in real life
we
proably would have a better chance of success, at least if we
were
given several decades of warning before the impact.
David Morrison, Director of Space
NASA Ames Research Center, MS 200-7
website: http://space.arc.nasa.gov
website: http://astrobiology.arc.nasa.gov
website: http://impact.arc.nasa.gov
======================
===============================
(3) 'MINI' ALIEN INVASION HITS THE EARTH
http://www.telegraph.co.uk
By Roger Highfield, Science Editor
SCIENTISTS have found that up to 4,000 tons of alien material
lands on
the Earth each year in the form of "micrometeorites"
less than one
millimetre in diameter.
For some time, it has been suspected that they account for most
of the
extra-terrestrial material arriving on the Earth but estimating
the
total annual impact of particles has been difficult. Now United
States
Army Cold Regions Research and Engineering Laboratory, of the
United
States Army Cold Regions Research and Engineering Laboratory, and
colleagues report a solution in the current issue of Nature.
The water in a well at the South Pole offers an ideal way to
collect
small meteorites, which are instantly frozen when they land on
the
snow, ensuring their preservation. By sucking water from the
bottom
well that supplies drinking water for the Amundsen-Scott research
station, researchers have collected thousands of well-preserved
and
dated micrometeorites.
Analysis suggests that about 90 per cent of the incoming mass of
submillimetre particles - about 40,000 tons - evaporates during
atmospheric entry. Several methods have been used to deduce the
origins
of micrometeorites. The presence of the isotopes helium-3,
beryllium-10, aluminum-26 and manganese-53 confirm that they come
from
space. Most micrometeorites have compositions that suggest that
they
originate in our solar system.
Dr Levern said: "Unfortunately, current analyses don't
identify the
specific sources within our solar system."
(C) 1998 The Daily Telegraph
==================================
(4) METEOR SHOWER THREAT?
From John Wagoner <stargate@gte.net>
SKY & TELESCOPE'S NEWS BULLETIN
While amateur astronomers eagerly await the Leonid meteor shower
in
November, aerospace professionals are a little worried. Every 33
years,
when the shower's parent Comet 55P/Tempel-Tuttle swings around
the Sun,
the Leonids often surge into a brief meteor
"storm." The comet rounded
our star earlier this year. Operators of Earth-orbiting
satellites are
concerned that the increase in cosmic debris could pose a danger
to
their equipment. To discuss the issues, engineers, astronomers,
and
aerospace insurers gathered on April 27-28 at the Leonid
Meteoroid
Storm and Satellite Threat Conference, held in Manhattan Beach,
California. There are many more billions of dollars worth of
equipment
in orbit now than there was during the last Leonid storm in 1966.
While
the true threat is uncertain, many companies aren't taking any
chances
and may turn off satellites during the predicted peak. Even the
Hubble
Space Telescope will be turned away from the stream.
Copyright 1998 Sky Publishing Corporation. S&T's Weekly News
Bulletin
and Sky at a Glance stargazing calendar are provided as a
service to
the astronomical community by the editors of SKY & TELESCOPE
magazine.
Widespread electronic distribution is encouraged as long as these
paragraphs are included.
==============================
(5) CALIBAN & SYCORAX: NEW NAMES FOR ICY MOONS OF URANUS
From Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
Cornell University News Service
Contact: David Brand
Office: (607) 255-3651
E-Mail: deb27@cornell.edu
Caliban and Sycorax
Astronomers propose names for their two recently discovered icy
moons
of Uranus
ITHACA, N.Y. -- Cornell University astronomer Philip Nicholson
and his
colleagues have proposed names for the two recently discovered
moons of
the planet Uranus. They are Caliban and Sycorax, both characters
in
Shakespeare's play "The Tempest." The names are likely
to be approved
by the International Astronomical Union.
The astronomers detail their discovery of the two moons in a
report in
the April 30 issue of the magazine Nature. They confirm that
Caliban
and Sycorax are the faintest planetary moons yet imaged by
ground-based
telescopes. The discovery of the two moons was reported on Oct.
31 by
Nicholson and colleagues Joseph Burns, professor of engineering
and
astronomy at Cornell, Brett Gladman of the Canadian Institute for
Theoretical Physics at the University of Toronto, and J.J.
Kavelaars of
McMaster University, Canada.
The team used light-sensitive semiconductors, called
charge-coupled
devices, attached to the 5-meter Hale telescope on Mount Palomar,
Calif., to track the irregular, or non-circular, orbits of the
two
moons. Regular satellites orbit near a planet's equatorial plane.
The
two moons are the first irregular satellites discovered around
Uranus.
Both Caliban and Sycorax, the astronomers write, are unusually
red in
color, which suggests a link with the recently discovered
populations
of comet-like bodies called trans-Neptunian objects, which orbit
the
sun beyond the orbit of Neptune, and Centaurs, which cross the
orbits
of the outer planets.
Both trans-Neptunians and Centaurs, say the researchers, have a
wide
range of reddish colors, perhaps resulting from the bombardment
of
their organic-rich icy surfaces. Nicholson says this bombardment
could
be from cosmic rays or from the sun's ultraviolet radiation. The
methane on the moons' surfaces, he says, would be
"cooked" by the
radiation into hydrocarbons, showing up as a dark red through a
telescope's filters.
The two moons, say the researchers, are presumed to have been
captured
by Uranus early in the history of the solar system. "My
guess is that
the moons were once trans-Neptunians and they became Centaurs and
were
captured by Uranus and became satellites," says Nicholson.
Since the
newly discovered moons are likely to have been captured by Uranus
soon
after its formation, the Nature article notes, "their
physical
properties may provide clues to conditions in the early solar
system."
The process of capture could have taken two forms, Nicholson
says. The
moons could have been trapped by Uranus gravity as they came
close to
the planet. Another theory, he says, is that in the early days of
the
solar system Uranus might have been surrounded by a gaseous
nebula that
would have caused a drag on the objects' movement as they came
close to
the planet.
Nicholson estimates that Caliban, the smaller of the two moons,
has a
diameter of 60 kilometers (37 miles) and is orbiting Uranus at an
average distance of about 7.2 million kilometers (4.5 million
miles),
taking 1.6 years to complete one revolution. Sycorax, he
estimates, has
a diameter of 120 kilometers (74.5 miles) and takes 3.5 years to
complete one orbit of Uranus at a mean distance of about 12.2
million
kilometers (7.5 million miles) from the planet. However, he says,
Sycorax has a much more elliptical orbit than Caliban, bringing
it as
close as 6 million kilometers (3.7 million miles) to the planet.
The composition of the two moons, says Nicholson, "is
probably a
plum-pudding mixture of rocks and ice."
All 15 previously known satellites of Uranus lie on fairly evenly
spaced, nearly circular orbits. Most recently Voyager 2, in 1985
and
1986, discovered 10 small, dark inner moons.
Jupiter has eight known irregular satellites, of which the last,
Leda,
was discovered in 1974. Saturn has one, Phoebe, discovered in
1898, and
Neptune has one, Nereid, discovered in 1949.
To see images of the two newly discovered moons of Uranus, go to
Gladman's page on the World Wide Web at
http://www.cita.utoronto.ca/~gladman/uranus.html.
==============================
(6) ASTEROID MAKES WAVES, ASTRONOMERS COMPUTE ...??
P. Daukantas: Update: Asteroids make waves ... Astronomers
compute ...
New E-journal surfaces. COMPUTERS IN PHYSICS, 1998, Vol.12, No.2,
pp.114-115. Copyright 1998, Institute for Scientific Information
Inc.
** Sorry, no electronic abstract available - but sounds rather
interesting ...
===============================
(7) STEPHEN J GOULD ON GULLIVER'S FURTHER TRAVELS
S.G. Gould: Gulliver's further travels: the necessity and
difficulty of
a hierarchical theory of selection. PHILOSOPHICAL TRANSACTIONS OF
THE
ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES, 1998,
Vol.353,
No.1366, pp.307-314
HARVARD UNIVERSITY, MUSEUM FOR COMPARATIVE ZOOLOGY, CAMBRIDGE,
MA,02138
For principled and substantially philosophical reasons, based
largely
on his reform of natural history by inverting the Paleyan notion
of
overarching and purposeful beneficence in the construction of
organisms, Darwin built his theory of selection at the single
causal
level of individual bodies engaged in unconscious (and
metaphorical)
struggle for their own reproductive success.. But the central
logic of
the theory allows selection to work effectively on entities at
several
levels of a genealogical hierarchy, provided that they embody a
set of
requisite features for defining evolutionary individuality.
Genes, cell
lineages, demes, species, and clades-as well as Darwin's favoured
organisms-embody these requisite features in enough cases to form
important levels of selection in the history of life. R. A.
Fisher
explicitly recognized the unassailable logic of species
selection, but
denied that this real process could be important in evolution
because,
compared with the production of new organisms within a species,
the
origin of new species is so rare, and the number of species
within most
clades so low. I review-this and other classical arguments
against
higher-level selection, and conclude (in the first part of this
paper)
that they are invalid in practice for interdemic selection, and
false
in principle for species selection. Punctuated equilibrium
defines the
individuality of species and refutes Fisher's classical argument
based
on cycle time. In the second part of the paper, I argue that we
have
failed to appreciate the range and power of selection at levels
above
and below the organismic because we falsely extrapolate the
defining
properties of organisms to these other levels (which are
characterized
by quite different distinctive features), and then regard the
other
levels as impotent because their effective individuals differ so
much
from organisms. We would better appreciate the power and
generality of
hierarchical models of selection if we grasped two key
principles:
first, that levels can interact in all modes (positively,
negatively
and orthogonally), and not only in the negative style (with a
higher
level suppressing an opposing force of selection from the lower
level)
that, for heuristic and operational reasons, has received almost
exclusive attention in the existing literature; and second, that
each
hierarchical level differs from all others in substantial and
interesting ways, both in the style and frequency of patterns in
change
and causal modes. Copyright 1998, Institute for Scientific
Information
Inc.
----------------------------------------
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*
LINEAR RESEARCH TEAM DISCOVERS SIX NEW PHOs IN APRIL ALONE
From Phil Burns <pib@nwu.edu>
A May 1, 1998 AP wire story about the NEO search project led by
Grant
Stokes can be viewed at:
http://www.cbs.com:80/prd1/now/template.display?p_story=41327&p_who=network
The story says that Stokes's group has discovered six
Earth-threatening
asteroids in the last five weeks.
-- Phil "Pib" Burns
Northwestern University, Evanston, IL. USA
pib@nwu.edu
http://pibweb.it.nwu.edu/~pib/
================
RESEARCHERS SPOT POTENTIAL THREATS TO EARTH
SATELLITE TECHNOLOGY USED FOR ASTEROID-HUNTING
From
http://www.cbs.com:80/prd1/now/template.display?p_story=41327&p_who=network
SOCORRO, New Mexico
(AP) A New Mexico research team has found six Earth-threatening
asteroids in the last five weeks, setting a new standard for the
pace
of asteroid-hunting.
The group is using an Air Force telescope at the north end of
White
Sands Missile Range near here to scan the skies for moving
objects. The
group then uses computer software to hunt through hundreds of
images
for anything that moves.
The team has been working on the project for two years, but has
begun
to find asteroids only since last November. The researchers have
since
found eight potentially hazardous asteroids - objects large
enough to
cause serious damage on Earth that have orbits crossing Earth's
path.
That's more than anyone else has found in a similar period,
according
to International Astronomical Union records. The team also found
a
comet, one of eight discovered so far this year.
"We're quite happy," said project manager Grant Stokes
of the
Massachusetts Institute of Technology's Lincoln Laboratory. He
spoke
about the work Monday at Space '98, a scientific conference in
Albuquerque.
An impact from space is believed to have led to the extinction of
the
dinosaurs 65 million years ago. Scientists believe a hit that
large is
a once-in-100-million-years event, but have calculated an
asteroid
large enough to cause [local, BJP] damage on Earth strikes as
frequently as once every 100 years.
A rock the size of half a football field dropped on Tunguska,
Siberia,
in 1908, lighting fires 10 miles away and snapping trees as far
away as
25 miles.
Stokes' team uses technology the Lincoln Laboratory developed for
the
Air Force to track satellites. Scientists realized the same
equipment
would be useful to hunt asteroids and have been able to piggyback
on
the satellite work, Stokes said.
"They're doing great work," said Brian Marsden, an
astronomer at the
International Astronomical Union whose job it is to keep track of
known
asteroids.
Marsden's group lists 118 known potentially hazardous asteroids
found
since 1932. None is likely to hit the Earth in the foreseeable
future,
but astronomers want to track them because of the possibility one
could
hit some day.
Stokes' project is one of three major asteroid-hunting efforts
under
way in the United States.
Copyright 1998 The Associated Press