CCNet DIGEST, 19 January 1999

    Ron Baalke <>

    NEW SCIENTIST, 16 January 1999, p. 43

    BBC News Online

    NASA Science News

    Timo Niroma <>

    R. Wieler, ETH ZURICH




From Ron Baalke <>

NEAR Clean-Up Hydrazine Engine Burn Scheduled for Jan. 20

A small hydrazine engine burn is scheduled for Jan. 20 at noon, EST.
This burn is intended to fine-tune the spacecraft's trajectory by
approximately one degree and to increase its speed by 31 miles per hour
(14 meters/second), allowing NEAR to gain on the faster-moving Eros
asteroid. This trajectory correction maneuver was planned following the
successful completion of the large bipropellant engine burn on Jan. 3.


From NEW SCIENTIST, 16 January 1999, p. 43


Book Review: Noah's Flood by William Ryan and Walter Pitman, Simon &
Schuster, $25, ISBN 0684810522

The sea is splashing round your ankles, and showering every sign of
rising. What do you do if you are one of the first farmers who
settled on fertile plains by the sea shore? First wonder, then worry,
then head for boats or the high ground, taking your essentials: food
stores, animals, seeds and a granny or two. It would be something you
would never forget, and your grandchildren would hear the Story of
the Rising Sea many times.

Such stories, of a great flood and how it was survived, are recorded
in the Bible and other ancient texts. But do these stories have any
factual basis? in NOAH'S FLOOD, Bill Ryan and Walter Pitman set out
to show that they do. There was a truly great flood around the Black
Sea, recounted orally and eventually in writing by descendants of the
scattered groups of survivors. Geology, climatology, archaeology,
linguistics, history and international subterfuge bordering on
espionage all play a part in a fascinating story that reveals as much
about how science works today as it does about the world 7000 years

Ryan and Pitman are geologists; their interest in this area began in
the early 1970s, at the time when the curious history of the
Mediterranean was first revealed. Around 6 million years ago, this sea
had become a hot desert, with shallow lagoons so rich in mineral
salts that little could live there. The waters returned abruptly,
flooding back through the Straits of Gibraltar in less than a
century. This idea seemed strange at first, but the evidence
collected by Ryan, among others, was incontrovertible.

A chance remark from a colleague set Ryan and Pitman wondering
whether a similar catastrophic flood could have been witnessed and
remembered as the story of Noah. Strands of evidence from diverse
fields slowly came together to implicate the Black Sea, around 5600
BC. The geography and climate were right for a spectacular refilling
of this inland sea; people lived there and may have moved to, for
example, the Middle East, bringing their tales of a disastrous flood
with them. The pieces finally began to fall into place with the aid
of precise methods dating archaeological and climatological records,
and, especially, a geophysical survey of the Black Sea.

Ryan and Pitman found the sea had shrunk and become a freshwater
lake, cut off from the oceans by a natural dam across the Bosphorus.
The lake was surrounded by plains where, they presume, people lived,
traded and may have been the first farmers. Eventually, the world's
oceans rose again and the flood came, with the waters advancing
around a quarter of a mile inland each day for a year or two. People
fled to start new lives elsewhere. These disparate groups are thought
to be the ancestors of, among others, the Sumerians who handed down
accounts of the great flood in Gilgamesh's tale.

The flood is a fascinating story, all the better for being told by
working scientists. What comes across clearly is the thrill of
discovery: being on the boat when the drill core brings up shallow
water sediments, from the floor of a deep sea, or seeing the
significance of observations made in the 19th century by intrepid
science-explorers. Parts of the book fling the reader almost too far
into the world of these individual scientists, but they also serve to
highlight the chances of the past century. Now collaboration breeds
success: gone are the days of the lone wolf researcher, competent in
every discipline.

But the scientific goal has not changed: all these researchers want
to understand is the world, past and present. Ryan and Pitman's book
is a mind-expanding read. The mixture of disciplines and ways of
doing science is exhilarating and paints a realistic picture of the
way research works. It makes you really wonder if similar hard
science might lie behind other folk-tales around the world.

Sue Bowler edits the Royal Astronomical Society journal, and teaches
earth sciences at the University of Leeds

Copyright 1999, New Scientist


From The BBC News Online

by BBC News Online's Science Editor Dr David Whitehouse

In just a few weeks time tiny Pluto will regain its crown as the most
distant planet orbiting the Sun. Soon afterwards however it may lose
its planetary status forever.

Pluto revolves around the Sun every 248 years in a highly elliptical
path. This means that for a few years every orbit it comes closer to
the Sun than Neptune, the next most distant planet.

That will end at 11.22 GMT on February 11th when it will cross
Neptune's path and once again become the solar system's most distant

It will be 220 years before it again comes closer than Neptune. But
long before that it may have been demoted from its status as a planet.

Depending upon an email vote among astronomers our solar system may
soon have eight instead of nine planets as all the textbooks say.

Always strange

Discovered in 1930 Pluto almost defies classification, there is no
other body quite like it. It is only two-thirds the diameter of our
Moon and it has a relatively large companion Charon, discovered in

Charon may have been born through a head-on collision between Pluto and
another large ice body, in much the same way as the Earth-Moon system
is believed to have formed.

According to computer models, some of the debris from this giant impact
on Pluto went into orbit around Pluto and coalesced to form Charon.

Made of a mixture of rock and ice Pluto has always been an oddity. It
neither qualifies as an Earth-like or a gas giant planet.

Very little is known about its surface. Images taken by the powerful
Hubble Space Telescope show only fuzzy details.

Experts disagree about what it is, but a growing number
say that if it was discovered now, it would never even
occur to them to call it a proper planet.

It may be the last survivor of a lost population of ice dwarfs that
inhabited the primeval solar system. It may even be an escaped
satellite of Neptune.

Last to be visited

Pluto's significance in the solar system has been a point of contention
since soon after it was discovered in 1930 by Clyde Tombaugh, an
astronomer at the Lowell Observatory in Arizona.

Since Tombaugh's death in 1997 pressure has grown for the International
Astronomical Union, the international authority for naming celestial
bodies, to take a tough line on Pluto.

The latest blow came in 1995 with the discovery of the first object in
the so-called Kuiper Belt. Since then about 60 more objects, made of
rock and ice and a few hundred km in size, have been found in the solar
systems cold outer reaches.

Pluto remains the only major body in the solar system not to have been
visited by a spacecraft. Plans are being drawn up for a mission called
the Pluto-Kuiper Express that would fly past Pluto after having spent
over ten years getting there.

One of the reasons scientists want to see it at close quarters is that
despite its small size and remote location, Pluto undergoes dramatic
seasonal changes.

As Pluto recedes from the Sun, much of its atmosphere is believed to
freeze out onto the surface. This explains the observation of fresh
white ice on its surface.

Copyright 1999, BBC


From NASA Science News

Scientists Present 1998 Earth-Temperature Trends
Updated 20-year temperature record unveiled at 1999 AMS Meeting

January 12, 1999: Since late 1978, polar-orbiting satellites have
monitored the microwave emissions from oxygen in the Earth's
atmosphere. These emissions, measured with the Microwave Sounding
Unit (MSU) instruments aboard TIROS-N weather satellites, are
proportional to the temperature of the atmosphere, and have allowed
scientists to build a 20-year record of the temperature of the Earth
as measured from space.


From Timo Niroma <>

The Helsinki temperature shows a curious temporary decline in 1867 and
similarly that year was so cold all over in Finland that the severe
frost caused a famine. A sizable percentage of the Finnish people died
of hunger. Already the January had a mean temperature of -13.1 degrees
C, which was rivalled only in 1893, 1942, 1985 and 1987. By comparison
the January 1866 had a mean temperature of -0.1 degrees. The April
temperature was -1.1 degrees C, rivalled only in 1881. This means the
second coldest April in 170 years (1829-1998).

May 1867 has then been the coldest in Helsinki during the last 170
years, mean temperature in Helsinki was only 1.8 degrees. This is not
only the record, but several degrees below the second coldest May. The
May 1866 had a temperature of 6 degrees, and the May 1868 a temperature
of 8 degrees. The mean temperature in 1961-1990 was 10 degrees. The
catastrophe was ready, June temperature being still below average, 12.2
degrees. Only the July and August were nearly normal, 15 degrees both,
but it was too late to get a normal harvest anymore and besides at
nighttime there were severe frost.

In fact, something peculiar happened already in September 1866. The
mean temperature was a high 14.3 degrees C, rivalled only in 1949 and

Although I here talk about Helsinki and Finland, there are similar
measurements of a year without spring in 1867 in many other places
around Europe and United States.

I have found three possible explanations.

1. Sun. As I show on my webpage
( there exists a clear
correlation between a low Sun (few sunspots) and a low temperature on
Earth and a high Sun (rich sunspot activity) and a high temperature.on
Earth. The most famous case is the Maunder minimum whose coldest decade
in 1690's was both spotless in Sun and cold on Earth. Also during the
1810's the Sun's activity was very low (in fact 1810 is the only
spotless year since 1749 since when we have monthly statistics). The
maxima in 1805 and 1816 are also the lowest ones after 1749. So Tambora
is not needed to explain the summerless year 1816 (although it may have
helped a bit to lower it still). The chill years began already years
before Tambora (for example the California cold in 1812-13).

In Helsinki temperature records (kept uninterruptibly since 1829) the
warmest decade measured by summer temperatures is still the 1930's. In
1930's there began in Sun a growing trend in intensity. At the moment
we are approaching surely the highest intensity for half a millennium,
possible the highest since the medieval high in the 12th century. This
correlates very well with the socalled "greenhouse warming". As in the
Tambora case Sun is also here all that is needed for an explanation of
the warming (see for example my web page, part 8). Correlation of
course doesn't mean a cause and effect relationship, but as statistics
is based on probability, the more we have these correlations, the more
confident we can be that such a relation exists. This of course does
not exclude other factors (such as Tambora or man) supporting the
ongoing tendency.

But in 1867? There was a sunspot minimum in 1867, but it was a typical
one, such that happens in intervals of 10-12 years, nothing like in
1689-90 or in 1810, which most probable were the main reason for the
cold decades of 1690's and 1810's, peaking 1695 and 1815-16,
respectively. In fact this cycle was the second highest in the 19th
century, so the Sun is not a likely explanation.

2. A volcano. The last frost event before 1867 in the United States
occurred in 1837 and can be correlated with the volcanic eruption of
Sopka in 1837 and the next occurred in 1884 and can be correlated with
Krakatoa in 1883. But the frost event of 1867 in Europe and 1866 in US
cannot be correlated with any known volcanic activity.

3. An impact. "In 1867 the largest recorded flood disaster occurred on
the Nepean River, Australia. When Saynor and Erskine (Australian
Journal of Marine and Freshwater Research 44(5), 1993) studied sediment
cores along the river, they were able to identify high-level flood
deposits dating to the 19th century inundation." A tsunami or flood is
of course not a cause-and-effect indicator of an impact, earthquakes
are more common reasons for tsunamis for example.

Now the big question is: was the anomalous frost event in 1866-67
caused by the same event that caused the flood disaster in 1867. And
furthermore, could this event have been an impact near the Australian
coastline, possibly of a size of 1 to 2 tunguskas?

Crowley-North: Paleoclimatology (Oxford 1991) indicates that this was
not a Finnish-Australian event. Paris Summer temperature was lowest
ever since the measurements began in late 18th century. The acidity of
the Greenland ice sheet dropped to its lowest value since 540 AD.

There was a frost ring in bristlecone pine in western US in 1866 as
previously mentioned. There had been 29 years from the previous frost
ring and would last 18 years to the next. The previous and the next are
neatly correlated with big eruptions of volcanous, but the 1866 frost
event not. There is also another intriguing question: why was the frost
event a year ahead in US than in Finland. If we assume an impact, it
must have happened in 1866. If it occurred near Australia, could it
have been possible that a blanketing dust veil prevailed over western
US in 1866 and drifted to Greenland and Finland only in 1867?

A further interesting thing is that the Greenland CO2concentration
dropped in 1868 from 240 ppm suddenly 180 ppm. There has been other
drops also at other times, but the other drops has lasted a year or
two, this lasted over a decade.

What then explains the a possible impact in 1866 and an Australian
flood in 1867. Tsunami isn't that slow. If one looks at the Nepean
area, the explanation is readily at hand. "Freshwater wetland
communities were once common in backswamps along the Nepean, Hawkesbury
and Georges Rivers and their tributary creeks. Most have now been
cleared or drained. Where they remain, permanent standing water with no
emergent vegetation occupies the lowest areas of large swamps. Around
this is more shallow water, with a zone of emergent vegetation." (D. H.
Benson: The Native Vegetation Of Western Sydney.) If this kind of land
gets a tsunami on it in 1866, it will still flood in 1867. 

Timo Niroma


R. Wieler: The solar noble gas record in lunar samples and meteorites.
SPACE SCIENCE REVIEWS, 1998, Vol.85, No.1-2, pp.303-314


Lunar soil and certain meteorites contain noble gases trapped from the
solar wind at various times in the past. The progress in the last
decade to decipher these precious archives of solar history is
reviewed. The samples appear to contain two solar noble gas components
with different isotopic composition. The solar wind component resides
very close to grain surfaces and its isotopic composition is identical
to that of present-day solar wind. Experimental evidence seems by now
overwhelming that somewhat deeper inside the grains there exists a
second, isotopically heavier component. To explain the origin of this
component remains a challenge, because it is much too abundant to be
readily reconciled with the known present day flux of solar particles
with energies above those of the solar wind. The isotopic composition
of solar wind noble gases may have changed slightly over the past few
Ga, but such a change is not firmly established. The upper limit of
similar to 5% per Ga for a secular increase of the He-3/He-4 ratio sets
stringent limits on the amount of He that may have been brought from
the solar interior to the surface (cf. Bochsler, 1992). Relative
abundances of He, Ne, and Ar in present-day solar wind are the
same as the long term average recorded in metallic Fe grains in
meteorites within error limits of some 15-20%. Xe, and to a lesser
extent Kr, are enriched in the solar wind similar to elements with a
first ionisation potential < 10 eV, although Kr and Xe have higher
FIPs. This can be explained if the ionisation time governs the FIP
effect (Geiss and Bochsler,  1986). Copyright 1999, Institute for
Scientific Information Inc.


B. Gustafsson: Is the Sun a Sun-like star? SPACE SCIENCE REVIEWS, 1998,
Vol.85, No.1-2, pp.419-428


Various observable properties of the Sun are compared with those of
solar-type stars. It is concluded that the Sun, to a remarkable degree,
is ''solar-type''. As regards its particular mass and age, and probably
its non-binarity, ''anthropic'' explanations may seem in place. The
possible tendency for the Sun, as compared with similar stars, to be
somewhat rich in iron relative to other elements needs further
exploration. This is also true concerning its presently small
micro-variability  amplitude. Copyright 1999, Institute for Scientific
Information Inc.

The Cassini Mission was launched  in October 1997 to study the physical
structure and chemical composition of Saturn as well as all its moons.
(1) Editorial
(2) A. Braccesi:  Gian Domenico Cassini in Bologna and his
contributions to the assessment of the planetary system. PLANETARY
AND SPACE SCIENCE, 1998, Vol.46, No.9-10, pp.1079- 1084
G. D. Cassini was hired as a professor of astronomy in Bologna in
1649, at the age of only 24, and left for Paris in 1669, when he was
44. We will outline in this Paper his major contributions to
astronomy during those year according to the judgement of the
scholars: the demonstration of the physical inequality of the Sun's
motion using the meridian line he had built in the church of S.
Petronio and the discovery of Mars and Jupiter rotation. The first
result unequivocally dismissed Aristotle's celestial mechanics based
on uniform circular  motions, pointing to the unity of the
terrestrial and celestial worlds; the second contributed to renew the
debate on whether the dynamical structure of the planetary system was
Ptolemaic or Copernican. In this respect, some recently discovered
lessons, which Cassini gave in Bologna in the year 1666, appear
enlightening. Excerpts are reported and commented upon. (C) 1998
Elsevier Science Ltd. All rights reserved.
(3) Titan in the solar system
(4) Some speculations on Titan's past, present and future
(5) The composition of Titan's atmosphere: a meteorological
(6) The dynamic meteorology of Titan
(7) Titan's ionosphere: A review
(8) Model of Titan's ionosphere with detailed hydrocarbon ion
(9) A three-dimensional MHD model of plasma flow around Titan
(10)A two-dimensional multifluid MHD model of Titan's plasma
(11)Dynamic escape of H from Titan as consequence of sputtering
    induced heating
(12)The temperature dependent absorption cross sections of C4H2 at
    mid ultraviolet wavelengths
(13)Cassini UVIS observations of Saturn's rings
(14)PPI results from the balloon drop experiment of the HASI pressure
    profile instrument
(15)The microwave sensing in the Cassini Mission: the radar from Jet
    Propulsion Laboratory (JPL
(16)Atmospheric calibration for precision Doppler tracking of
(17)Imaging spectroscopy of Saturn and its satellites: VIMS-V
    onboard Cassini
(18)An imaging spectrometer operating in the visible near
    infrared for the study of planetary surfaces
(19)VIRTIS: an imaging spectrometer for the ROSETTA mission
(20)Atmospheric studies with spectro-imaging: prospects for the
    VIMS experiment on Cassini
(21)Investigation of Saturn's atmosphere by Cassini
(22)Analysis of dynamic performances of HASI temperature sensor
    during the entry in the Titan atmosphere
(23)Cassini Huygens mission: the exploration of the Saturn system.
    Radio science experiments: Radio Frequency Instrument
(24)Evolution of icy surfaces: an experimental approach
(25)Imaging Saturn's dust rings using energetic neutral atoms
(26)Cassini radar: system concept and simulation results
(27)Cassini as a heliospheric probe - the potential of pick-up
    ion measurements during its cruise phase
(28)Scientific objectives and implementation of the Pressure
    Profile Instrument (PPI/HASI) for the Huygens spacecraft
(29)An Italian tracking station for Cassini
(30)Dynamically depleted zones for Cassini's safe passage beyond
    Saturn's rings
(31)The Cassini-Huygens SSP refractometer: REF
(32)Doppler receiver for Cassini radio science experiments
(33)Fluid dynamics of liquids on Titan's surface

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    Ian Crawford <>

    Walt Hadley <>

    Andrew Y. Glikson <>


From Ian Crawford <>

I am grateful to all those who have contributed to the debate
following my "swords into spaceships" contribution. However, it seems
to me that several contributors have missed the essential points of
my argument, which I would like to take this opportunity to clarify.

The first point is that my original note was in response to Andrew
Glikson's argument that expenditure on space development is difficult
to justify ethically because the resources are required to improve
conditions here on Earth. I certainly agree that there are many
global developmental and environmental projects which are more
deserving of support than space exploration. HOWEVER, as the world
spends about $1 trillion p.a. on military hardware, and only about
$0.02 trillion p.a. on civilian space projects, it is nonsensical to
criticise the latter on ethical grounds without trying to do
something about the former (especially since the military spending is
positively dangerous, whereas the much cheaper space programmes are
at least harmless and, arguably, positively beneficial for economic,
social and scientific reasons).

Having made this comparison, the next point is whether we should go a
stage further and actually advocate financing space development by a
transfer of resources from the (very large, but utterly unproductive)
military sector of the world economy. I have presented these
arguments in the articles already referenced (New Scientist 19 May
1990, p. 67; Space Policy vol. 11, p. 219, 1995) and won't reiterate
them all here. However, I would say that I am slightly disappointed
by Pete Worden's "been there, done that" approach. Of course it is
disappointing that nothing came of the SEI, however that isn't an
argument for giving up. The basic argument remains valid: the Cold
War has ended, the military still soaks up at least 50 times the
resources currently devoted to space projects, the military
contractors are, very largely, the same ones that would be called
upon to develop a space infrastructure, and a transfer of resources
from one to the other would therefore be largely compatible with the
powerful corporate and political interests involved. What we need to
do is to keep making the case.

I have to say that I disagree profoundly with Jim Benson's arguments.
It cannot be true to say that we cannot "afford taxpayer's dollars to
.... subsidize humans in space." If the US can afford $300 billion
p.a. on maintaining a vast military infrastructure (this being
approximately the US share of the $1 trillion p.a. global arms budget
referred to above) then it can certainly *afford* a (say) $100
billion p.a. space programme (roughly ten times NASA's current
budget) PROVIDED that resources are transferred from one to the other
(there being no other sector of the economy from which such a
transfer would be socially or politically justifiable). Of course,
the extent to which this will ever be politically possible will
depend on perceptions of the geopolitical environment, and on
resulting political imperatives. However, as citizens who presumably
want to live in a peaceful (and disarming) world, and who believe in
the importance of space exploration/colonisation for the future of
humanity, I believe that we should keep trying to draw these
arguments to the attention of policy makers.

Finally, I would like to express my agreement with Louis Friedman,
and therefore disagreement with Benson, about the role of government
in space. Of course private enerprise will have a role in developing
the space frontier, but before this is likely to be significant it
will be necessary to build up some sort of space infrastructure (e.g.
economic ground-to-orbit spaceplanes, space stations, interplanetary
transports, lunar and planetary outposts). Private industry is most
unlikely to take the risk of building up such an infrastructure when
the economic returns are so distant and so uncertain. Infrastructural
development is an appropriate economic role for government, and space
infrastructure will be no exception.

Ian Crawford


From Walt Hadley <>


The concepts of peace and tranquility and little or no military budgets
is a wonderful concept. It is also remarkably stupid!  As a retired
military officer, (line officer) I would very much like to live in a
world like this. What I would like to know is how do some people
propose to rid the human race of the people that start wars, make
biological and nuclear weapons, make war on their neighbors. In my
life of 66 years, I have seen no peace nor any sign of a time when we
would not need a strong military, even in periods as now when we do
not have one.

Walter H. Hadley
Major      USAFR


From ANDREW Y. Glikson <>

Dear Benny,

I like to respond to comments by Julian Hiscox (CCNet 8.1.99) (my
reply points 1-4) and Ian Crawford (CCNet 13.1.99) (my reply point 5)
"Defence of the realm and space colonisation" (CCNet 8.1.99), in the
context of biological evolution and human survival:

1. Survival of the oldest life forms: The present-day Shark Bay
stromatolite species (Cryptozoon) is of course different from the 3.5
billion years-old Pilbara species - the point in my letter relates to
the longevity of single-celled colonial organisms, exceeding that of
other species and that of Homo Sapiens by a factor larger than
700 000 000. I am unaware of confirmation of early Archaean
stromatolites from Greenland, where the main evidence for life comes
from isotopically light carbon inclusions in apatite.

2. Biological success of parasitic versus symbiotic organisms: The
survival of infectious micro-organisms, such as the smallpox virus,
measles virus, pneumonia mycoplasms or tetanus germs, depends
critically on the availability of human carriers, on the longer term
survival of the carriers - which these micro-organisms often kill -
and on critical carrier population densities.  Unless these
conditions are met, such micro-organisms recede to remote niches.  By
definition these species are self-limiting, as compared to symbiotic
species.  For Homo Sapiens the corollary is evident - good planets
are hard to come by.

3.  Exponential growth and the purpose of life:   If the sole
biological purpose of life is the promotion of the "Selfish Gene"
(Richard Dawkins) through exponential growth aimed at maximising
mutational diversity, does human intelligence lie in (1) blind
adherence to "survival of the fittest" theories (whose consequences
this century are evident) or (2) in an intelligent and ethical choice
in favour of the qualitative value of life and of bio diversity?
This of course raises the question of determinism versus free

4.  Prehistoric humans and modern civilisation:   The point to bear
in mind is that pre-historic humans have lived on Earth for some 5
million years in (relative) equilibrium with their environments,
developing an daptability that allowed them to survive calamities
such as asteroid/comet  impacts.

Projectile size/frequency plots suggest that over 5000 impacts by
bodies larger than 100 meters occurred during the last 5 million
years (see fig. 13-1 in Verchuur's "Impact", Oxford University Press,
1996). Regarding the "barbarism" or otherwise of Amazonian tribes -
as J. Hiscox may be aware, some of the worst fatalities suffered by
these people were due to infected blankets deliberately dropped from
planes over their villages for many years ...

5. Arms into spaceships: I am in support space exploration for
scientific purposes, and could not agree more with Ian Crawford that
conversion of arms into spaceships is much preferable to, as well as
less destructive than, military expenditures.  The point is - by any
economic estimate the costs of space colonisation (establishment of
human colonies on planets and moons) would exceed that of space
exploration (remote control surveys) by orders of magnitude.

Following western democratic principles, surly whether the remaining
$$$trillions extracted from Earth's fast dwindling resources should
be used for environmental restoration, alleviation of hunger, or/and
space colonisation, is an issue which should be a subject for an
informed public debate, including inputs by life scientists
(biologists, botanists, foresters, soil scientists, meteorologists)
with their understanding of the survival requirements of terrestrial
living systems. The $$$hundreds of billions now expended on attempts
to avert the Y2K bug underpin the futility of purely tehcnological
solutions to the human condition.  Had such sums been used to plant
enough trees - the progressive encroachment of the terrestrial
deserts could perhaps be arrested, as well as jobs provided to young
unemployed generations in many parts of the world ...

Choices relating to space exploration and colonisation go far beyond
purely technical questions - but constitute major economic, social
and ethical issues.

Andrew Glikson
16 January, 1999



From Mark R. Kidger <>


I wrote a small piece on Pluto before the British media broke the Pluto
story. Here is my text, based on an article which will appear in "The
Astronomer" this month and which was put on my Web site here in
Tenerife at Christmas.

Mark Kidger



Mark R. Kidger
Instituto de Astrofisica de Canarias

According to a report published in the Boston Globe just before
Christmas, the Nomenclature Committee of the IAU (actually the
Executive Committee of Division III) has been holding an Internet vote
over Christmas to decide on the fate of the planet Pluto. Within a very
few weeks now, according to the Boston Globe article, Pluto may cease
to be officially a planet and the solar system may return to its 8-planet status.

This story was picked up by the Spanish media around Christmas and has
reached the British media this week. However, it seems that the Boston
Globe was a little quick off the mark to downgrade Pluto with its news
story. Gareth Williams at the Minor Planet Center issued a rapid denial
of the story by Christmas, which was published on the Internet. In
fact, the idea is to give Pluto "dual citizenship" as a planet and the
king of the Trans-Neptunian Objects. This would even permit a similar
double status for Ceres in the future.

For some time now it has become obvious that the outer solar system
needs to be tidied up.. The number of TNOs (Trans-Neptunian Objects),
making up the inner edge of the Kuiper Belt, has increased steadily, to
approach 100. After the initial lack of follow-up observations of many
of these objects such that at least one of the first discovered (1993
RP) is totally and unretrievably lost, reliable orbits are being
calculated for a reasonable number of objects, although about half have
still only been observed at a single opposition (often along an arc of
only a few days). There is still a significant risk that a sizeable
fraction of TNOs, particularly the fainter ones, may be lost still.
Others, fortunately, are now multiple-opposition objects and are
beginning to satisfy the criteria for numbering.

At the current rate of asteroid discovery, Number 10 000 could have
fallen as early as the January batch of Minor Planet Circulars, where
new numbers are allocated. In fact, in January, after two months where
more than 150 asteroids had been numbered, had a smaller crop and, at
present, we are "only" at asteroid 9913 - when, twenty years ago, the
prediction was made that 6000 might be reached by the millennium!

With asteroid 10 000 there is an obvious breakpoint to number TNOs. A
logical thing to do is to number the best-observed now with 10
000-series numbers, to distinguish them from "normal" asteroids and
maybe add new TNOs at 15 000 and 20 000 (at the current rate, 20 000
may be reached around mid-2005).

For some time now it has become clear that Pluto is nothing more than
the largest of the objects of the Kuiper Belt. In fact, there is a
whole class of TNOs with similar orbits which are called - Plutinos -
little Plutos - which, it seems, are similar to their big brother in
all but their size. Many times in the past the status of Pluto has been
questioned and now it is being questioned more insistently than ever.

What would the reasons be for down-grading Pluto? Even for those
emotionally tied to it as a planet, they are fairly convincing. It is
now known that the mass of Pluto is only about one fifth of the mass of
the Moon and, as such, it is very hard to claim that Pluto really is a
planet. However, this still means that its mass is about 1.5x1022kg -
ten or more times the mass of Ceres, the largest asteroid. In fact, of
the known TNOs, Pluto is still about a factor of 100 more massive than 
any other, apart from its satellite Charon and Charon is, by far, the
second largest known TNO.

Doing some very rough numbers, it is likely that Pluto and Charon make
up more than 50% of the mass of all the TNOs found to date. This makes
Pluto an object intermediate in size and mass between the asteroids and
Kuiper Belt comets on the one hand, and even Mercury, the smallest
planet, on the other. This still marks Pluto as a special type of
object, which deserves a special status, but probably not as a genuine
major planet.

As I understand it, the plan is to make Pluto asteroid number 10 000,
but the Minor Planet Center has denied that there is any plan to remove
its planetary status. The title of the Boston Globe story, "Planetary
Demotion" is misleading because Pluto will be both asteroid number
10 000 and the ninth planet simultaneously. Other TNOs will then follow
as 10 001, 10 002, etc.

The reason for the dual status is that there is a strong case for both
sides. Pluto can be considered a major planet because, like the others,
it is a gravitationally collapsed body (i.e. its interior has been 
differentiated as a consequence of heating by the collapse of its
mass), quite apart from the historical reasons which are so important
to many people. However, as the largest object in the Kuiper Belt,
there is undoubtedly a very strong case for including it as a minor
body like the other Trans Neptunian Objects, quite apart from the fact
that its mass is far smaller than for any other major planet.

By giving to Pluto the number (10000), in addition to retaining it as
the ninth planet, we are giving Pluto a unique and very special status.
This potentially allows Ceres to be given some kind of similar double
status at a future date, as the largest object of the Asteroid Belt.

The alternative proposal is to start a fourth list of solar system
bodies (after the planets, the comets, and the asteroids). The group
that supports this idea would like to designate Pluto as K/1 (for
Kuiper Belt Object #1), or TN-1 (for Trans-Neptunian Object #1). The
problem with this option is obvious. There is a whole group of objects
which are neither normal asteroids, nor strictly Trans-Neptunian - the
Centaurs. Some Centaurs have already been numbered, the first being
(2060) Chiron (although some might argue that (944) Hidalgo should also
be considered a Centaur), but more have been added. Some Centaurs are
recognised as having their aphelion in the Kuiper Belt and are probably
objects in transfer orbits, others, may be dead or inactive comets. The
question obviously arises of how to treat the Centaurs on this scheme
and even of how to define a Centaur.

The numbered sequence (1)-(9913), or (1) - (10 000), merely indicates
high-quality orbits of small objects of stellar appearance orbiting the
sun. As Pluto's observable disk is actually smaller than that of
several asteroids, it is undoubtedly "of stellar appearance", unlike
Uranus and Neptune which do have easily resolvable disks.

Just to make the debate a little more interesting, some people even
argue that Pluto has actually shown itself to be an active comet. When
it reached perihelion, sublimation for its surface gave rise to an
extensive temporary atmosphere (a coma), which is recondensing as Pluto
moves away from the Sun. If you really wanted to be difficult you could
suggest that Pluto should be renamed C/1930 B1 (Thombaugh), or C/1930
B1 (Pluto) - it could not be a periodic comet unless the rule stating
that only objects of less than 200 years orbital period should be
designated as a periodic comet. This was the solution adopted for
Chiron which is now designated both (2060) Chiron (as an asteroid) and
as 95P/Chiron (as a periodic comet observed now at three perihelion
passages since 1895 and at no less than 29 oppositions). If the same
rule were followed for Pluto, it would become 141P/Pluto, always
supposing that the 200-year period rule could be waived. Such a
solution would certainly maintain Pluto's name and give it a special
status. The objection here is that comets and planets are clearly
different type of object, whilst asteroids and planets are generically
similar - to have an object classed as comet and planet would take us
back to the days of Velikovsky.

However, designating Pluto as 141P/Pluto does not have the element of
"ceremonial gesture”" which beholds its status as, after all, it would
be just another comet. In contrast, asteroid 10 000 does lend itself to
ceremony, particularly as the Minor Planet Center has traditionally
arranged a celebration every 1000 asteroids and to reach number 10 000
is a major landmark which should be marked by something more
distinguished than a tiny, rock which is never brighter than magnitude 
20 (which most of the new numbered asteroids are). This makes Pluto a
fitting candidate.

The most intriguing option though is that, assuming number 10 000 is
not reached in the January list of new minor planet designations, it
would be reached in the February list which should be released on or
about February 10th 1999. This, as was pointed out by the Dutch
scientific journalist, Govert Schilling, would coincide with the day
when Pluto crosses Neptune's orbit towards aphelion and, once again,
becomes the most distant planet. If you want a symbolic gesture, what
finer one could there be than that!

Copyright 1999, Mark R. Kidger

CCCMENU CCC for 1999