PLEASE NOTE:

• Information circulated on the cambridge-conference network is for
  scholarly use only. The attached text may not be reproduced
  or transmitted without prior permission of the copyright holder.

*

CCNet, 059/2000 - 19 April 2000
-------------------------------


     "University of Maryland astronomer Michael A'Hearn said the
     belated discovery showed the holes in a US-led programme to detect
     space objects that could pose a potential threat to the Earth. The
     scheme is skewed in favour of detecting large asteroids -- those
     which are bigger than one kilometer (five-eighths of a mile)
     across -- rather than comets, he said. This is because asteroids
     do not move very far from Earth and return close to our planet
     every few years, making  their path easy to calculate. Comets, on
     the other hand, have a much wider variety of orbits and make a
     flyby at much longer periods, making it far more difficult to
     calculate any change in their trajectories.
     A'Hearn said that since the start of 1997, 22 newly discovered
     comets had come as close to the Sun, or closer, than K2 -- and 11
     of them have passed inside Earth's orbit. Such findings raised
     questions about the priority given to comet detection and the
     viability of conventional spotting methods, he said."
       --SpaceDaily, 18 May 2000


(1) CRITICISM OF NASA'S SPACEGUARD SURVEY IS GETTING LOUDER
    Benny J Peiser <b.j.peiser@livjm.ac.uk>

(2) MISSED COMET PUTS SPOLIGHT ON SPACEGUARD
    SpaceDaily, 18 May 2000

(3) WHAT ARE THE IMPLICATIONS OF COMET C/1997 K2?
    Ron Baalke <baalke@jpl.nasa.gov>

(4) SOHO-SWAN COMET C/1997 K2
    Jonathan Shanklin <jdsh@mail.nerc-bas.ac.uk>

(5) GALILEO ZOOMS IN ON IO'S AMAZING VOLCANOES
    Andrew Yee <ayee@nova.astro.utoronto.ca>

(6) OPEN UNIVERSITY ANNOUNCES EXPANSION IN PLANETARY SCIENCE
    Iain Gilmour <I.Gilmour@open.ac.uk>

(7) NEODYS & ORBFIT ANNOUNCEMENT
    NEO Dynamic Site <neodys@newton.dm.unipi.it>

(8) U.S. COULD BUILD MISSILE SHIELD WITHOUT TREATY CHANGES
    SpaceDaily, 18 May 2000

(9) ANTIMISSILE SYSTEM'S FLAW WAS COVERED UP, CRITIC SAYS
    The New York Times, 18 May 2000

(10) NEOS & THE FUTURE OF ENERGY FROM SPACE
     Michael Martin-Smith <martin@miff.demon.co.uk>

(11) NUCLEAR SOLUTION?
     Loren Ball <emlnob@bellsouth.net>


==========
(1) CRITICISM OF NASA'S SPACEGUARD SURVEY IS GETTING LOUDER

From Benny J Peiser <b.j.peiser@livjm.ac.uk>

In recent months, a number of American researchers have been on record
for claiming that NASA's Spaceguard goal, and hence the management of
the impact hazard, is now close to being under control. While Clark
Chapman believes that no further NEO search programmes are needed at
all to achieve NASA's goals, Al Harris has been quoted as saying that
one more telescope should do the trick. 

It is difficult to say whether this view is a result of American
over-optimism or whether it's due to the lack of a genuine
understanding and appreciation of the overall impact hazard. Whatever
the reasons may be for underestimating (and hence mismanaging of) the
impact hazard, it could soon be that NASA’s flawed Spaceguard goal will
be blamed for the failure of NEO surveys to detect comets such as
C/1997 K2 and others.

Thankfully, a growing number of experts in the field have become
increasingly critical about NASA's narrow-minded obsession with large
asteroids. These critics have made clear in no uncertain terms that
smaller asteroids as well as comets comprise a much larger chunk of the
overall impact hazard than is generally accepted by NASA managers, and
that its restricted Spacegurad Survey is seriously flawed in this
respect.

Now, as a result of comet C/1997 K2, Mike A'Hearn, a NEO reseacher at
the University of Maryland and a senior official of the International
Astronomical Union (IAU), has cast further doubts over the current
Spaceguard goals. According to a Spacedaily report (see below), A'Hearn
is concerned about the implications of comet C/1997 K2 that failed to
be detected by ground-based searches. A'Hearn claims that the belated
discovery of this comet

   "showed the holes in a US-led programme to detect space objects
   that could pose a potential threat to the Earth. The scheme is
   skewed in favour of detecting large asteroids -- those which are
   bigger than one kilometer (five-eighths of a mile) across -- rather
   than comets, he said. This is because asteroids do not move very far
   from Earth and return close to our planet every few years, making
   their path easy to calculate. [...] Such findings raised questions
   about the priority given to comet detection and the viability of
   conventional spotting methods, he said."

What is more, A'Hearn also makes clear that we still don't know what
overall threat comets actually pose. "For our peace of mind, it is
important to know whether comets represent 10 percent of the potential
large impacts on Earth (as is commonly thought) or a much larger
fraction," he said.

A'Hearn's warning is is a timely reminder that - in spite of all the
hype, PR, over-optimism - we are still far from getting a grip on the
impact hazard. To tell you the truth, we're still ages away from a
planetary civilisation that is in control of our cosmic environment.

Benny J Peiser

=====================
(2) MISSED COMET PUTS SPOLIGHT ON SPACEGUARD

From SpaceDaily, 18 May 2000
http://www.spacedaily.com/news/spaceguard-00a.html

Paris (AFP) May 18, 2000 - A comet passed through the solar system
unnoticed three years ago, raising doubts about the effectiveness of an
international early-warning system to spot space wanderers that could
smash into Earth.

Astronomers at the Finnish Meteorological Institute reported in the
British weekly journal Nature Thursday that the comet was one of a
group of five that raced through the solar system between May and July
1997.

The four others had already been observed, but no one detected the
fifth, even though it was bright enough to be observable by amateur
astronomers in their back gardens, according to the team.

It was only when the Finns belatedly assessed data recorded by an
instrument aboard a US-European Sun-monitoring satellite, SOHO, that
they made the discovery. The fifth comet has been dubbed K2.

The instrument, SWAN, is designed to study the solar wind -- the
streams of hot gas emitted by the Sun -- by sensing hydrogen atoms
emitted at ultraviolet wavelengths.

"Because the comet was almost constant in brightness over several
months, it should have been easily observable from the ground," the
authors say, adding that this "underlines the need for full-sky
surveillance of comets."

In an adjoining commentary, University of Maryland astronomer Michael
A'Hearn said the belated discovery showed the holes in a US-led
programme to detect space objects that could pose a potential threat to
the Earth.

The scheme is skewed in favour of detecting large asteroids -- those
which are bigger than one kilometer (five-eighths of a mile) across --
rather than comets, he said.

This is because asteroids do not move very far from Earth and return
close to our planet every few years, making their path easy to calculate.

Comets, on the other hand, have a much wider variety of orbits and make
a flyby at much longer periods, making it far more difficult to
calculate any change in their trajectories.

A'Hearn said that since the start of 1997, 22 newly discovered comets
had come as close to the Sun, or closer, than K2 -- and 11 of them have
passed inside Earth's orbit.

Such findings raised questions about the priority given to comet
detection and the viability of conventional spotting methods, he said.

"For our peace of mind, it is important to know whether comets
represent 10 percent of the potential large impacts on Earth (as is
commonly thought) or a much larger fraction," he said.

Asteroids or comets can wreak astonishing destruction if they penetrate
the Earth's protective atmosphere.

A large object, believed to be up to 10 kms (six miles) long, smashed
into Mexico's Yucatan peninsula 65 million years ago, triggering a
firestorm and a dust cloud that wiped out the dinosaurs, scientists
believe.

In 1908, an asteroid or comet about 60 metres (200 feet) long exploded
over Siberia with the force of 600 times the Hiroshima bomb, reducing a
40-km (25-mile) wide patch of forest to matchwood.

In January, US astrophysicists put the number of major asteroids at
around 700, with a margin of error of plus or minus 230.

These are classified as bodies ranging in size from one to 10
kilometers (half a mile to six miles) whose swing around the Sun takes
them relatively close to the Earth's orbit.

However, the vast majority of dangerous objects between 100 metres
(yards) and one km (five-eights of a mile) have still to be detected,
although the risk of any collision is considered extremely remote
(sic!).

Copyright 2000 AFP. All rights reserved.

==========
(3) WHAT ARE THE IMPLICATIONS OF COMET C/1997 K2?

From Ron Baalke <baalke@jpl.nasa.gov>

From Soace.com 18 May, 2000
http://www.space.com/scienceastronomy/solarsystem/missed_comet_000517.html

Astronomers Find Fleeting Comet
By Maia Weinstock
18 May 2000

In the spring and early summer of 1997, stargazers were treated to a
beautiful sky show with the passing of wispy-tailed Comet Hale-Bopp.
But scientists now say that while all eyes were on this dazzling sight,
another near-Earth comet slipped quietly through the sky unnoticed.

Astronomers analyzing archived data from the European Space Agency/NASA
Solar and Heliospheric Observatory (SOHO) spacecraft have recently
reported the presence of a never-before-detected comet, which flew
close to Earth in 1997. The comet, temporarily dubbed C/1997 K2, was
apparently brighter than every comet discovered by astronomers in the
six months preceding its appearance, adding to the mystery of how such
a prominent comet may have zoomed past Earth unseen.

"To say we were surprised would be a bit of an understatement," said
Finnish astronomer Teemu Mäkinen, lead author of a paper in this week's
Nature, which describes the new comet discovery. "It sounded quite
unlikely [to us] that a comet of such magnitude could elude both
professionals and amateurs alike."

Despite its brightness, Comet K2 would not have been visible to the
naked eye. Yet even "inexpensive amateur equipment would have sufficed"
for stargazers to see the comet, said Mäkinen. "I believe that many
amateurs were lured by the spectacular display of the concurrent Comet
Hale-Bopp," he explained.

Eluding the pros

Professional astronomers could have easily spotted the comet, since the
equipment they use is much more powerful than the average telescope. So
here's the question: how did they miss it? The combination of vast
expanses of space and limited resources with which to scan them are the
most likely reasons, experts say.

"Our records are patchy, especially at high latitudes," said Mäkinen.
"It was probably missed by dedicated surveys because of its trajectory,
which went through the southern ecliptic pole."

Though it slipped by unnoticed by human eyes, evidence for the K2 comet
was captured by SOHO's Solar Wind Anisotropies (SWAN) instrument from
May to July of 1997.

The SWAN instrument is not dedicated to comet discovery. Rather, it was
designed to observe emissions of hydrogen around the sun at ultraviolet
wavelengths. But these emissions, known as Lyman-a emissions, are also
given off in high quantities by comets. As a result, though its
resolution is relatively poor, the instrument is also sensitive to
comets.

Could we miss the big one?

The discovery of Comet K 2 raises an interesting question: How prepared
are we to track near-Earth objects, including comets and asteroids. If
we missed this comet, some experts ask, what are the chances that we'll
miss a comet that's heading straight for Earth?

A great deal of work has taken place to locate and categorize
near-Earth objects like comets and asteroids. Although it may sound
like science fiction, scientists say that the threat of comet impacts
on Earth is very real.

To highlight the threat of such an impact, Massachusetts Institute of
Technology professor Richard P. Binzel even created a scale to measure
the probability that a given object will hit Earth and cause it harm.
Called the Torino scale, this method of measurement highlights the fact
that Earth's current environmental balance is precarious, and it and
the life that depends on it could be devastated in one swift blow.

So what are the chances of a comet hitting Earth, or of astronomers
missing a potentially dangerous on-coming object. No one really knows.
What astronomers do know, however, is that better funding for continual
sky scans would help them map all comets that streak through the solar
system.

"It is just a matter of prioritization. Do we want to use limited
resources on preventing something that is likely to happen every day
and cause moderate casualties -- like traffic accidents -- or something
that will happen once in 30 million years but has potential for wiping
out all of humankind?" asked Mäkinen. "In such situations,
unfortunately, myopia is usually bliss."

===========
(4) SOHO-SWAN COMET C/1997 K2

From Jonathan Shanklin <jdsh@mail.nerc-bas.ac.uk>


The are a few points that seem to have been missed in the information released
about comet 1997 K2:

1. It is not a near earth comet. The closest it approached was 1.17   
   AU.
2. The comet was not observable from most of the northern hemisphere. 
   The discovery clearly shows that there are some objects which would
   always be missed by a northern hemisphere search program.
3. Looking at a comet catalogue doesn't tell you if the comet was
   observable. Of the six LASCO comets mentioned in the Nature review
   only one was actually observable, even by the search programs.
4. Some of the amateur discoveries are close to the sun rather than out
   of the ecliptic. This area is not searched by most programs.
5. The comet is very unlikely to have been visible in binoculars when
   its brightness is estimated to have not exceeded 11th magnitude.
6. The comet passed around 5 degrees north of the Large Magellanic
   Cloud around 1997 July 7 when it could have been near 11th
   magnitude. It might show on some amateur pictures as the moon was
   then near new.

It is a pity that the Nature review does not highlight the need for a
southern hemisphere search program.

Jon Shanklin
j.shanklin@bas.ac.uk
British Antarctic Survey, Cambridge, England
http://www.nbs.ac.uk/public/icd/jds

==============
(5) GALILEO ZOOMS IN ON IO'S AMAZING VOLCANOES

From Andrew Yee <ayee@nova.astro.utoronto.ca>

News Services
University of Arizona

Contacts:
Alfred S. McEwen, 520-621-4573, mcewen@pirl.lpl.arizona.edu
Elizabeth Turtle, 520-621-8284, turtle@lpl.arizona.edu
Paul Geissler, 520-621-621-2114, geissler@pirl.lpl.arizona.edu
Jani Radebaugh, 520-621-1632, jani@lpl.arizona.edu

18 May 2000

Galileo's sharp new pictures of Io detail amazing volcanism

By Lori Stiles

(EDITORS: For images, go to the Planetary Imaging Research Laboratory -
Galileo web page: PIRL/Galileo,
http://pirlwww.lpl.arizona.edu/~turtle/Releases/Releases.19_May_2000.html)

When the Galileo spacecraft flew close by Jupiter's moon, Io, late last
year and early this year, it took sharpest-ever pictures of the best
volcanic show in the solar system.

Galileo took more than 100 high-resolution images during Io flybys on
Oct. 11, Nov. 26 and Feb. 22. Results include pictures of an active
lava flow as long as the Grand Canyon, a mile-high curtain of burning
lava, a unique long-lived "wandering" volcanic plume, and a
6-mile-diameter lava lake that shines steady as a beacon. The Galileo
imaging team reports the results in the May 19 issue of Science.

"Io is absolutely fascinating because every single thing we see is
completely new and completely unexpected," said Jani Radebaugh, a
graduate student at the University of Arizona who helps analyze the
photographs. "You can take what you know about volcanology and about
planetary processes, but in every picture we see, there's something new
going on that we don't understand. There's something brand new, every
time."

"Io is like a laboratory for large-scale volcanic experiments," said
Alfred S. McEwen of the Galileo imaging team. McEwen directs the
Planetary Imaging Research Laboratory (PIRL) at the UA Lunar and
Planetary Lab (LPL). "We don't have controlled laboratories big enough
to study these processes. And large-scale volcanic fields on Earth are
very modified. So here's a place we can watch the changes and really
understand how this activity might happen at this scale. With that
insight, we can go back and reconsider what happened in Earth's past."

"I like Io as a model of what might be going on under the crust of
Europa," said Paul Geissler, senior research associate at LPL and
member of the Galileo imaging team. "The whole (jovian moon) system is
a great exercise in comparative planetology," Geissler said. "You have
four separate moons, separated at birth, and they've grown up
completely differently. So it's very important to study them from that
point of view."

The Galileo imaging scientists are trying to understand how Io's
extraordinary volcanism fits within the big geologic picture of the
moon and the jovian system. They'd like to discover the composition of
Io's crust. They'd like to know if Io's interior holds a magma ocean --
a question images alone won't answer. They use Galileo to explore how
volcanoes erupt and modify the landscape, what the lavas are made of,
and how Io's strange terrain forms and evolves.

Results discussed in the Science article include --

* Pele -- Pele is a very unusual volcano, even for Io, in that it
consistently shines brightly. The new images show it to be an active
lava lake about 10 km (6 miles) across. Galileo imaging and spectral
data show it must be at least 1,030 degrees Celsius (1,890 Fahrenheit).
Nighttime pictures of Pele taken in October show a hot, glowing line at
the margin of the Pele caldera. The researchers interpret this line to
be where molten lava pushes against the caldera walls and is exposed,
breaking through the edges of the crust that covers the lava lake. (A
caldera is a depression that forms from collapse over a magma chamber.)

* Pillan -- New high-resolution images of Pillan Patera, show a complex mix
of pits, domes, channels and possibly rafted plates near a 70-km lava
flow that erupted in June 1997. Such channels and rafted plates form
when lava erupts at flow rates violent enough to destroy stable crust
-- a kind of volcanism also seen on Mars and Earth. But pits and domes,
which range in size from a few tens of meters to many hundreds of
meters in diameter, are harder to explain. Possibly, They are vents of
plumes, analogous to volcanic "rootless cones" on Earth.

The new images also reveal color properties of the dark diffuse 
deposits around Pillan that provide the first evidence that silicate
particles are spewed more than 100 kilometers high in Io's plumes.

* Zamama -- The new images show the primary vent at the westernmost end
of the 100-km-long dark flow (roughly the length of Arizona's Grand
Canyon) with lava flows forming a radial pattern around the vent. The
75-km Zamama plume comes not from the primary vent, but from the center
of a lava field extending to the east.

* Prometheus -- Prometheus is Io's most faithful, persistent plume. It
has been seen in every image of the area taken by Voyager, Galileo and
Hubble Space Telescope. Remarkably constant in size, shape and
brightness throughout its observed history, Prometheus had "wandered"
between 75 to 95 km west in the 20 years between the 1979 Voyager flyby
and the 1996 Galileo flyby. In 1996, Galileo also saw a new dark flow
extending between the Voyager-era and the Galileo-era plume sources.

McEwen and others on the Galileo imaging team had suggested that  
Prometheus comes not from the primary vent, but from the end of a lava 
flow -- an argument that some of their peers questioned. The new
Galileo evidence strengthens the UA researchers' case.

The latest Galileo images and spectra show two main hot spots. One is
15 km south of the caldera and marks where lava spews from a fissure to
the surface. The other hot spot, 80 km to the west, is where the
100-km-high Prometheus plume rises above active lava beds.

"The new Io images pretty strongly confirm the view that the plume
comes from the lava flow, not the volcano," McEwen said. "But that
doesn't mean we understand it." Although Prometheus erupts at 10 times
the rate of Kilauea, Earth's most active volcano, it in many ways
resembles Kilauea, only on a larger scale, McEwen said. However, he
added, "Prometheus' plume and its behavior is totally alien from
anything seen on Earth."

* Emakong Patera -- Emakong is one of the largest calderas on Io
without an observed "hot spot." It features a brightly colored surface
that may be sulfur lava flows. The images show that at some point lava
filled the entire 40-km diameter caldera and overflowed. This has
happened at a much smaller scale at Kilauea in Hawaii.

Emakong and many other calderas on Io are irregular in shape, rather
than circular, as are Earth's calderas, Radebaugh said."That tells us
there are interesting things going on underneath the surface of the
crust. There's probably fractures and some stresses that make those
irregular shapes when the surface collapses.

* Tvashtar Catena -- A lava "curtain", or line of lava fountains, rises
to 1.5 km above a linear fissure within one of the calderas. On Io, as
on Earth, lava erupting from a fissure can create a curtain of fire
along the fissure. But because Io's atmospheric pressure is a billion
times less than the Earth's, because Io's gravity is lower and its lava
is hotter, Io's lava fountains can reach 100 times higher than those on
Earth.

* Mountains and related landforms -- Researchers know of about 100  
mountains on Io that do not appear to be volcanoes. Io's mountains
resemble tilted blocks bounded by steep scarps, said LPL research
associate Elizabeth Turtle of the Galileo imaging team. The highest
mountain known on Io is 16 km high, Turtle said. The new photos suggest
an intriguing association between mountains and calderas, which may
help explain how both form, she added.

The sharp new Galileo photos show that several mountains have calderas 
cut into their sides. The photos also suggest that mountains and
calderas are geologically related in other ways. For example, Turtle
said, rising plumes of new material in Io's mantle may concentrate
stresses acting in Io's crust, causing it to fail, forming mountains by
thrust faulting. As the mountains are tilted up, layers of weak,
sulfur-rich material deposited by Io's plumes may fail, resulting in
tremendous landslides.

From a mosaic of new pictures of the lava-filled depression called
Hi'iaka Patera and its two bordering mountains, UA graduate student
Windy Jaeger speculates that Io's crust there might have been laterally
pulled apart. It may be only coincidence that the north and south
parts, if pushed together, would fit together like pieces of a puzzle,
Jaeger said. At this point, evidence is only circumstantial.

But if Hi'iaka Patera was once pulled apart, McEwen said, "that would
be very surprising, because on Earth a movement on that scale is
associated with plate tectonics. But we see no evidence for plate
tectonics on Io. There again might be some unique Ionian process
involved."

==========
(6) OPEN UNIVERSITY ANNOUNCES EXPANSION IN PLANETARY SCIENCE

From Iain Gilmour <I.Gilmour@open.ac.uk>

17 May 2000

OU Announces Expansion in Planetary Sciences

The Open University is set to double its research and teaching
commitment in planetary and space sciences in recognition of the
immense scientific, technical and public interest in solar system
exploration. From 1 July, the Open University's Planetary Sciences
Research Institute (PSRI) headed by Professor Colin Pillinger and the
Unit for Space Sciences and Astrophysics (USSA) formerly at the
University of Kent at Canterbury (UKC) will amalgamate to form an
interdisciplinary supergroup on the OU's Milton Keynes campus. From
that date Professor Tony McDonnell, and Drs John Zarnecki, Simon Green
and Neil McBride from UKC will be joining the OU staff.

The two groups have complimentary interests, with the benfits from
their fusion being far greater than the sum of the component parts.
PSRI's background is primarily geological and chemical, USSA's is
mainly from physics. Whereas PSRI can provide microbiology and life
sciences, USSA bring practical astronomical observation and
mathematical modelling. The approved space mission involvement of both
groups, including Rosetta, Beagle2, Cassini Huygens, Stardust, and
Genesis will bring a stream of mutually beneficial results over the
next decade. 

Contact PSRI <mailto:psri@open.ac.uk> for further information
Planetary Sciences Research Institute
http://psri.open.ac.uk
The Open University
http://www.open.ac.uk

================
(7) NEODYS & ORBFIT ANNOUNCEMENT

From NEO Dynamic Site <neodys@newton.dm.unipi.it>

PLEASE FIND ENCLOSED TWO ANNOUNCES, ONE ABOUT THE NEAR EARTH ASTEROIDS ONLINE INFORMATION SYSTEM NEODyS AND ONE ABOUT THE ASTEROID ORBIT DETERMINATION SOFTWARE ORBFIT. (We have decided to merge the two mailing lists to avoid annoying you with too many messages).

============================================================

Announcement about NEODyS vers. 3.0.

============================================================

NEODyS ANNOUNCEMENT

The Near-Earth Object Dynamics Site (NEODyS) has been significantly
improved and expanded.

NEODyS is an online information service for near-Earth asteroids
(NEA's), available since March 1999. At its core, NEODyS is a database
of orbital and observational information for each NEA; however, the
distinguishing feature of the system is the degree to which the
information is made accessible and searchable. NEODyS can be accessed
via the WWW at <http://newton.dm.unipi.it/neodys/>.

In NEODyS every NEA has its own "home page" containing sections
devoted to the object's orbit, observations, planetary close
encounters, additional services, and physical information. Also every
observatory has its own page with links to tables of all NEA
observations from that station.

One of the most valuable features is the database query facility. One
may of course look up an asteroid by name or number, but it is also
possible to search for all NEA's possessing some desired orbital or
observational characteristics, or to search for close approaches
within a given distance.

The new features available since May 2000 are the following:

1) A new layout has been designed

2) A new online help facility is available; please report any
   missing/obscure help text.

3) Proper elements are now computed for each NEA, using a new
   algorithm for averaging of planet crossing orbits. Encounter
   conditions, suitable for the identification of parent bodies of
   meteor streams, are also provided.

4) Besides the MOID (Minimum Orbital Intersection Distance) we now have
   a table showing all the critical points of the distance function,
   with a graphical illustration of orbital geometry and distance
   function.

5) Radar observations are now incorporated into our orbital solutions
   with greater accuracy, thanks to the use of a better Earth rotation
   model.

6) The statistical weigthing of optical astrometry, according to the
   historical performance of the observatory, has been improved by
   using adaptive time intervals.


The database is automatically updated on a daily basis as new
observations are released from the Minor Planet Center. All of the
data files needed to reproduce the NEODyS results are freely
available, even the OrbFit software used for orbit determination
<http://newton.dm.unipi.it/~asteroid/orbfit>.

The system is being upgraded and improved continuously, comments and
suggestions are welcome. Among the improvement we are working on are:

A) Complete list of all *possible* close approaches until 2050 (This
data is presently maintained privately as part of our recently
implemented automatic monitoring of the impact risk for all NEA's, but
we hope to put it in a publishable form soon.)

B) Inclusion in the database of the asteroids which are not NEA
according to the nominal, best fit orbit, but nevertheless could be
NEA.

NEODyS has been created by A. Milani (Department of Mathematics,
University of Pisa, Italy) and S. Chesley (while he was at Univ. Pisa;
current address JPL, Pasadena, USA). It is currently maintained by A. Milani,
M.E. Sansaturio (University of Valladolid) and G.F. Gronchi (University
of Pisa).

======================================================

Announcement about OrbFit version 2.1.1

======================================================

Dear OrbFitters and dear friends,

This message announces the new improved distribution
2.1.1 of the free software OrbFit.

The purpose of the software system we are distributing, maintaining
and continously upgrading, is to make available to observers of
asteroids an easy to use but accurate and reliable software to compute
preliminary orbits, ephemerides, improved orbits (by differential
corrections), identifications, and other auxiliary functions, to allow
the processing of astrometric observations and the planning of
observational campaigns (for example to recover lost objects).

Main improvements with respect to 2.0 are:

1) New observation weigthing, according to past performance of
each observatory, with adaptive time intervals.

2) Radar observations are handled with more accuracy, thanks to a
better Earth rotation model.

3) Software to detect and track Virtual Impactors is now included in
the distribution.

4) A new main program, catpro, allows to propagate the catalogs of
orbital elements, in both the single-line and multi-line formats.

5) The Radau integrator has been written in a modern, structured form;
moreover, when the orbit is computed with Radau and the variational
equations are being solved, the state transition matrix is
renormalized after each close approach; this is important for
performance in presence of multiple close approaches.

We are presently working toward several improvements, described in the
file README.workinprog.

Please note the ftp server has moved; we apologize for the
inconvenience, but we have been forced to move because of hackers
attacks.. The software can now be obtained at:

ftp://copernico.dm.unipi.it/pub/orbfit

A README file to be found therein provides all the necessary
instruction for installation on all flavours of UNIX and WINDOWS
computers.

This software system has been developed by a consortium including
A. Milani (Pisa University), S. Chesley (JPL), M. Carpino
(Astronomical Observatory Milano/Brera), Z. Knezevic (Astronomical
Observatory Belgrade), G. B. Valsecchi (CNR Rome), M.E. Sansaturio
(University of Valladolid).

The distribution of the software orbit9 is being reorganized; an
announcement on the availability of this software, together with the
software to produce proper elements of main belt asteroids, will be
issued soon.

Copyright (C) 1997-2000 OrbFit Consortium

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

To contact us:

milani@dm.unipi.it
marsan@wmatem.eis.uva.es
carpino@brera.mi.astro.it ,
giovanni@ias.rm.cnr.it ,
zoran@aob.bg.ac.yu ,
steve.chesley@jpl.nasa.gov


================
(8) U.S. COULD BUILD MISSILE SHIELD WITHOUT TREATY CHANGES

From SpaceDaily, 18 May 2000
http://www.spacedaily.com/news/bmdo-00z.html

by Matthew Lee

Washington (AFP) May 18, 2000 - The United States is prepared to 
proceed with a controversial national anti-missile shield even if it is
unable to get Russian agreement on modifications to a treaty banning
such systems, a senior official said Thursday.

Overcoming vehement Russian objections to revising the 1972 
Anti-Ballistic Missile (ABM) treaty which bans nationwide systems
capable of shooting down incoming missiles will be a key issue at
next month's summit between President Bill Clinton and his Russian
counterpart Vladimir Putin.

The State Department official, speaking on condition of anonymity, said
Clinton would not present the national missile defense (NMD) plan as a
"fait accompli" at the summit but indicated the president would make a
decision later this year on deployment based on US interests.

"If we do not reach an agreement of some kind with the Russians on the
changes to the ABM treaty necessary to proceed with a deployment
decision ... and if the president decides ... that it is in the
national interest to still go ahead with a deployment decision, he will
go ahead with a deployment decision," the official told reporters.

Clinton's decision will be based on four well-known criteria -- the
system's cost, its technological feasibility, the extent of the missile
threat to the United States from so-called "rogue states," particularly
North Korea, and its impact on arms control generally.

The objections of Russia, which sees NMD as a threat to itself, as well
as those of China and many US allies in Europe, who fear deployment
will spark a new nuclear arms race, will be factored into the fourth
criteria, the official said.

However, he added, "at the end of the day, the president is going to
make his decision on one criterion: What is in the long-term national
interest of the United States?"

FULL STORY at
http://www.spacedaily.com/news/bmdo-00z.html

================
(9) ANTIMISSILE SYSTEM'S FLAW WAS COVERED UP, CRITIC SAYS

From The New York Times, 18 May 2000
http://www.nytimes.com/library/national/science/051800sci-missile-defense.html

Antimissile System's Flaw Was Covered Up, Critic Says

By WILLIAM J. BROAD

A prominent antimissile critic has found what he says is a major flaw
in the Pentagon's antimissile plan and is calling on the White House to
appoint a high-level scientific panel to investigate what he says were
fraudulent efforts to cover it up.

If the critic is correct, the flaw may cripple or even kill the
proposed weapon system, the cost of which is estimated at up to
$60 billion.

The critic is Theodore A. Postol, professor of science and national
security studies at M.I.T., author of many reports on antimissile
systems and in the 1980's a science adviser to the chief of naval
operations on ballistic missile technologies and potential weapons
against them. He made his new accusations in a May 11 letter to John D.
Podesta, the White House chief of staff, after reviewing Pentagon data
gathered by an antimissile whistle-blower.

Dr. Postol's critique centers on the hardest part of the missile
defense challenge, distinguishing incoming weapons from decoys and
destroying them.

In the letter, a copy of which he gave to The New York Times, Dr.
Postol said Pentagon sensor data he had obtained from the first
antimissile test flight in June 1997 showed that the ground-based
interceptor was inherently unable to make the distinction and that the
Pentagon and its contractors had tried to hide this failure.

FULL STORY at
http://www.nytimes.com/library/national/science/051800sci-missile-defense.html

=============================
* LETTERS TO THE MODERATOR *
=============================

(10) NEOS & THE FUTURE OF ENERGY FROM SPACE

From Michael Martin-Smith < martin@miff.demon.co.uk >

From CCNet, 18 May 2000:
>Their scenario envisions a world in which one-third of all energy comes
>from fossil fuels; one-third from renewable resources, like solar and
>wind power; and one-third from nuclear power.
>
>To achieve that ambitious goal, all the nations of the world would have
>to consume less oil, coal and natural gas than they do today, while
>increasing renewable and nuclear energy sources at least tenfold.
>
>To accomplish that will require increasing the number of nuclear
>reactors on Earth from about 430 to roughly 4,000, which means that
>more than one nuclear reactor would have to be built every week for the
>next 50 years.

The same could be said of another  potentially less controversial
scheme - solar power satellites. These too would produce clean
non-greenhouse gas emitting energy, would be renewable, and would
require a major industrial effort - this time  in Space. However, the
controversial issues of nuclear waste and dissemination of dangerous
technology would not arise. In short, it may offer a truly sustainable
route to a clean but advancing civilization. To be practicable we would
need a considerable beefing up and focussing of our space industries,
especially as studies show that this option really requires that most of
the basic raw materials are mined off planet rather than from the deep
gravity well of Earth herself.

Considering that this Group is heavily centred on asteroid/cometary
neocatastrophism it seems appropriate to consider ways of deflecting or
better yet turning such hazards to ur profit. By consuming NEOs in the
service of clean solar power for civilization, we have a chance to kill
two birds with one stone...

The time may yet come when we can see a nespaper headline - "Near Earth
Objects - Armageddon or Eldorado!"
--
Michael Martin-Smith

====================
(11) NUCLEAR SOLUTION?

From Loren Ball < emlnob@bellsouth.net >

Hello Benny,

The latest article on nuclear power omits a very basic problem that
seems to always be overlooked. <<According to the Department of Energy,
the United States has 104 nuclear reactors in operation today.
Twenty-eight have been shut down permanently since 1953, and there are
no plans to build new ones.>>

Unless I am sadly mistaken, no two plants in this country are alike.
That is, any given plant must learn to live with its own peculiar set
of problems and cannot use the history of its neighbors to any
advantage because each is unique. This seems like a silly way to spend
a few billion dollars. The obvious answer to me is in economy of scale.
Let's simply decide on a design and freeze it so we can build a dozen
or so that are identical. A huge part of each plant's budget is in
design. Am I missing something here?
       
Thanks,

Loren C Ball
Emerald Lane Observatory 843

----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
The CCNet is a scholarly electronic network. To subscribe/unsubscribe,
please contact the moderator Benny J Peiser < b.j.peiser@livjm.ac.uk >.
Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at http://abob.libs.uga.edu/bobk/cccmenu.html

CCCMENU CCC for 2000