CCNet DIGEST, 5 May 1998

    Ed Grondine <>

    David Morrison <>

    Roger Highfield, Science Editor, The Daily Telegraph


    Ron Baalke <>


    S.G. Gould, Harvard University


From Ed Grondine <>

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

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

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,
                                           E.P. Grondine


From David Morrison <>

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

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


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


From John Wagoner <>

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.


From Ron Baalke <>

Cornell University News Service

Contact: David Brand
Office: (607) 255-3651

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


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 ...


S.G. Gould: Gulliver's further travels: the necessity and difficulty of
a hierarchical theory of selection. PHILOSOPHICAL TRANSACTIONS OF THE
No.1366, pp.307-314


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

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From Phil Burns <>

A May 1, 1998 AP wire story about the NEO search project led by Grant
Stokes can be viewed at:

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




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

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

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

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