CCNet 52/2002 - 22 April 2002

"Where were the people carrying the "Down With Asteroids" signs
during this past weekends protests against everything in Washington?
Why isn't the World Wildlife Federation demanding that Congress do
something to end this threat to world wildlife? Why didn't Al Gore
denounce President Bush for failing to counter the threat from above during
his 35th or so coming-out speech in Florida? Probably because
anti-asteroid activism doesn't pay the bills or procure the votes."
--Charles Rousseaux, Washington Times, 22 April 2002

    Andrew Yee <>


    Washington Times, 22 April 2002

    Andrew Yee <>

    Hermann Burchard <>

    Bob Kobres <>

    Ananova, 22 April 2002


>From Andrew Yee <>

[ ]

Friday, April 19, 2002, 3:31 PM EDT

NASA axing orbital debris research program
By IRENE BROWN, UPI Science Correspondent

JOHNSON SPACE CENTER, Texas (UPI) -- Budget overruns are prompting the
National Aeronautics and Space Administration to end its 23-year-old Orbital
Debris Program Office on Oct. 1, space agency officials admitted on Friday,
even though orbital debris is acknowledged as a serious problem for the
space shuttle, International Space Station and satellites in low-Earth

At 17,500 mph, even a fleck of paint can be dangerous for spaceships and
satellites in orbit. A four-inch chuck of metal flying at the space shuttle
could be fatal for any human in its path.

NASA as well as commercial and scientific satellite operators still have the
U.S. Space Command tracking data for debris large enough to be spotted by
optical and radar telescopes on the ground. The military currently tracks
about 10,000 objects daily that are bigger than 4
inches in diameter so satellite operators can move their spacecraft to avoid
being hit.

But clouds of smaller fragments born in rocket explosions, as well as other
small objects hovering in near-Earth orbits, will be left largely unstudied
as a result of the NASA office closing, reportedly for cost-cutting reasons.

"There were nine explosions in orbit last year and each creates more and
more debris," said Nicholas Johnson, head of the Johnson Space Center
Orbital Debris Program Office, which since its founding in 1979 has been
modeling the small particle debris environment, issuing forecasts,
recommending preventative measures and assessing risks.

"Radars cannot track small debris in the same manner as larger objects. We
do a statistical evaluation, based on optical observations of particles as
small as two millimeters. We can see them, but we don't know where they'll
be tomorrow. We do assessments of probabilities of how many particles are at
what altitude," Johnson said.

The analysis is one factor NASA takes into consideration when setting launch
dates and times for the space shuttle. The research also has been key to
identifying sources of orbital debris and setting national and international
guidelines for debris prevention and mitigation.

"We're sitting here hoping that someone will find a solution," said Johnson.
"This is a problem that's been coming for a long time. We're terminating a
key capability."

A NASA safety advisory panel issued a report earlier this year calling for
the agency to reconsider its decision.

"Over the last several decades, NASA has led an international effort to
understand how the space environment is impacted by the presence of
micrometeoroid/orbital debris," wrote the Aerospace Safety Advisory Panel.

"This work ... has provided a growing ability to track such objects and to
maneuver spacecraft, including the space shuttle and International Space
Station to avoid collisions ... Proposed budget cutbacks would eliminate
funding for the activities of this group, (depriving) the shuttle and
station programs of updated knowledge on debris risks."

Scientists warn that the orbital debris environment may become even more
dangerous if the United States proceeds with plans to develop a space-based
missile defense system -- whether from testing the system in space or in
actual conditions of a missile attack.

"In science fiction movies like 'Star Wars' there are constant explosions,
but a few seconds later the screen is clean. It's not going to work that way
near a planet," said physicist Joel Primack, with the University of
California, Santa Cruz.

"The space debris aspect of a 'Star Wars' missile system is just not talked
about in the public arena," said Primack, who was scheduled to present a
paper on Friday at the United Nations Educational, Scientific and Cultural
Organization headquarters in Paris.

"If we do this, we're going to create a terrible problem there's no easy
solution for," Primack said.

Copyright 2002 United Press International. All rights reserved.


Over the past forty years scientists have discovered that asteroids and
comets have collided with the Earth throughout its 4.5 billion year history.
The impact of these Near Earth Objects with our planet can be catastrophic
still represents a natural hazard today.

The NEO Information Centre provides services to the public, educators, media
and scientists to encourage understanding and advancement of NEO science.
Our virtual exhibition and online activities allow users to learn about the
nature of NEOs and the hazard they pose, find out what efforts are being
made to detect NEOs and what could be done to overt a collision. We keep you
informed with the latest news on NEO issues and enable you to voice your
opinions through discussion forums and special events. We provide materials
for educators, information and contact services for the media, and support
for NEO scientists in communicating and conducting their work.


Our goal is to increase public awareness and understanding of impact hazards
so that everyone, whatever their background knowledge, can make informed
decisions on NEO issues. We aim to provide a platform by which NEO science
is communicated to the public and media in an accurate and yet
understandable way. Our services also providing a resource by which the
media can find the information and experts they need.

Through an active programme of events and discussion we aim to enable the
public and scientists to voice their opinions on NEO issues and ensure that
these are heard by policy makers. At the same time we aim to clearly explain
current policy and existing research programmes.


The NEO Information Centre was established by the UK Government in response
to the recommendations of the Task Force Report on potentially hazardous
Near Earth Objects to provide accurate and level-headed information on Near
Earth Objects to the public and media and to support the international NEO
science community.

The Centre is operated by a consortium lead by the National Space Centre in
Leicester. Additional members of the consortium are the Natural History
Museum, Queen Mary and Westfield College, Queen's University Belfast, the
Royal Observatory Visitors Centre, the University of Leicester, the UK
Astronomy Technology Centre and W5. Regional exhibitions will be housed with
many of the consortium members.

The Centre is advised by an academic network of leading scientific NEO
experts and is administered by the British National Space Centre for the UK


Our partners are organisations involved in NEO research and the
communication of science to the public and media. Together we provide
accurate and understandable information on NEO issues to a wider and more
diverse audience.

Key partner organisations of the NEO Information Centre are:

The British National Space Centre

The BNSC is the UK government department charged with ensuring a safer
near-earth environment. It co-ordinates with other agencies on the threat
from Near Earth Objects.

The Minor Planet Centre

The Minor Planet Centre plays a crucial role in NEO observation programmes
by cataloging new observations of asteroids and comets. The MPC ensures that
astronomers can obtain the information they need to follow up new


The NEO Information Centre is operated by a consortium of organisations and
is led by the National Space Centre in Leicester. The management team

Ms Alex Barnett (Project Manager) (more info...)

Mr Kevin Yates (Project Officer) (more info...)

Dr Matthew Genge (Web Manager) (more info...)

The Academic Network which advises the NEO Information Centre comprises:

Prof Iwan Williams (Astronomer, Queen Mary's and Westfield College)
Dr Alan Fitzsimmons (Astronomer, Queen's University, Belfast)
Dr Matthew Genge (Planetary Scientist, Natural History Museum)
Dr Monica Grady (Planetary Scientist, Natural History Museum)
Dr John Davies (Planetary Scientist, UK Astronomy Technology Centre, Royal


>From Washington Times, 22 April 2002

Charles Rousseaux

On this 32nd anniversary of Earth Day, it's important to remember that the
Jeremiahs of the environmental movement actually do have it right. One day,
life as we know it will be wiped off the Earth.

It has happened before, and it will again, not as a consequence of evil
corporate capitalism, but rather devastating orbital dynamics. There are
about 1,000 large asteroids capable of hitting the Earth flying around the
solar system at a speed and recklessness that defy comparison. They hit
hard, too. About 65 million years ago, a chunk of space rock hit near the
Yucatan Peninsula, exterminating 75 percent of the life forms living on
Earth at the time, including all the dinosaurs (except for Fidel Castro).
Other asteroids have had similarly deep impacts on the Earth's ecology.

Alarmingly, NASA scientists recently calculated that a fairly large rock
innocuously named 1950 DA has a chance of ruining the weekend plans of
everyone on Earth.

So where is the outrage? Where were the people carrying the "Down With
Asteroids" signs during this past weekends protests against everything in
Washington? Why isn't the World Wildlife Federation demanding that Congress
do something to end this threat to world wildlife? Why didn't Al Gore
denounce President Bush for failing to counter the threat from above during
his 35th or so coming-out speech in Florida?

Probably because anti-asteroid activism doesn't pay the bills or procure the
votes. NASA scientists consider 1950 DA "a greater hazard than any other
known asteroid," but calculate that its chances of causing an Armageddon are
only 1 in 300. Besides, that close encounter that won't come until 2880, a
distant threat that is death to fund-raising and ballot-box appeal. Instead,
environmental activists and Democratic operatives will spend today attacking
big producers, big polluters and big Republicans, who, if you believe the
rhetoric, have nothing better to do than kill spotted owls, drop arsenic
into the water and breathe sulfur dioxide into the air.

However, the quality of the U.S. environment has never been better,
according to the "Index of Leading Environmental Indicators 2002," a study
just released by the Pacific Research Institute. Authors Steven Hayward and
Julie Majeres noted that the total emissions of six "criteria" pollutants
regulated by the Clean Air Acts have declined by almost a third since 1970,
even though the U.S. economy has grown by almost the same amount since then.
Water quality is up, releases of toxic chemicals are down, and supplies of
energy are still abundant, despite the best efforts of Senate Democrats.

That shouldn't be surprising, since most Americans want a clean, safe
environment, even if they don't bother to join the Sierra Club. Yet most of
them also realize that neither they nor their children can be protected from
all hazards at all costs.

Last year, NASA spent $4.5 million on the Near Earth Object Program, which
is designed to identify and discover 90 percent of the 1 kilometer and
larger asteroids in near-Earth orbit by 2008. That's .03 percent of it's $15
billion annual budget, two-ten thousandths of a percent of the $2.13
trillion budget for fiscal year 2003 that President Bush sent to Congress.
The NASA scientists I talked to seemed to think the level of funding was
about right, based on the low-risk nature of the threat.

Defense got a much bigger chunk of our tax dollars, and rightfully so. After
all, Osama bin Laden probably isn't hiding in the asteroid belt. A less
distant, but also less certain threat is global warming, allegedly caused by
industrialized countries' increased emissions of carbon dioxide. Those
releases could be cut by an infinitesimal amount by following the strictures
of the Kyoto Protocol, but only at a catastrophic price. According to
skeptical environmentalist Bjorn Lomborg, the $150 billion cost of one
year's worth of compliance with the Kyoto treaty would be almost enough to
buy every inhabitant of the Third World basic access to sanitation, water,
health and education - twice.

Those sorts of cost-benefit calculations are supposed to be a basic part of
political decision-making. Yet ironically, many of the same politicans and
activists who apply a pragmatic approach to procuring votes and demanding
dollars will spend today demanding environmental protection at all costs.

Still, there's still reason for optimism this Earth Day. After all, the sky
isn't scheduled to fall until 2880.
Charles Rousseaux is an editorial writer and an editor for the Commentary
pages of The Washington Times.

2002 News World Communications, Inc.


>From Andrew Yee <>

Informnauka (Informscience) Agency
Moscow, Russia

E.A. Kuzicheva, N.B.Gontareva
Institute of Cytology
Russian Academy of Sciences
St. Peterburg
+7 (812) 247-18-29,

Natalia Reznik, Informnauka (Informscience) Agency, 7-095-2675418



The eternal question about the origin of life on the Earth has no answer so
far. One of the theories assumes that life on the Earth might have
originated in space. Russian scientists successfully reproduced the
experiment carried out by Nature three and a half billion years ago.

Life originated on the Earth more than 3.5 billion years ago. However, the
scientists are still disputing over the possible sources of the life origin.
The matter is that life on our planet evolved from the molecular level to
the level of bacteria organisms within 0.5 - 1 billion years, this period
being very short for such an important evolutionary step. The researchers
are still racking the brains over this mystery. One of the popular
hypothesis asserts that some germs of life have been brought to the Earth
from space. But what exactly could have been brought from space and how
could the germs have originated in space?

E.A. Kuzicheva and N.B.Gontareva, research assistants from the Institute of
Cytology, Russian Academy of Sciences, have confirmed a possibility of
abiogenous synthesis of complex organic compounds (monomeric units of
nucleic acids) on the surface of comets, asteroids, meteorites and
space dust particles in the outer space. Therefore, it is possible that the
above monomeric units of nucleic acids could have got to the Earth and thus
could have significantly reduced the time period of the evolution process.
On the surface of space bodies the scientists have found all kinds of
various organic molecules (amino acids, organic acids, sugars etc.) and the
components required for their synthesis. Obviously, it is there that organic
substances are being synthesised, but the researchers can not be sure of
this fact, until the experiments confirm their assumptions.

The scientists from St. Petersburg reproduced synthesis of one of the DNA
components -- 5'-adenosine monophosphate (5'-AMP) under the conditions
specially designed to simulate the space environment. In order to synthesise
5'-AMP it is required to combine adenosine and inorganic phosphate.

On the Earth the reaction goes in the solution, but there are no solvents
whatsoever in space, therefore the researchers dried them in the air and got
a pellicle. Synthesis requires energy. The major source of energy in the
outer space both at present and in the prebiotic period of the Earth history
has been the solar ultraviolet radiation of different wavelengths.
Therefore, the pellicles were irradiated by a powerful ultraviolet lamp.
Naturally, the synthesis was carried out in vacuum, and the researchers used the lunar soil,
delivered to the Earth by the 'Moon-16' station from the Sea of Abundance,
as a model of the comet, meteorite, interplanetary or cosmic dust. The soil
represented basaltic dust of the dark-grey colour, the diameter of its
particles being less than 0.2 millimetres.

After 7-9 hours of ultraviolet irradiation of the dry pellicles the
scientists acquired several compounds, mainly 5'-AMP, one of the DNA/RNA
monomers. The energy of radiation does not promote synthesis alone, it also
facilitates decomposition of the initial and newly-synthesised compounds,
the more powerful the radiation is, the more extensively the decomposition
goes. However, the lunar soil provided some protection. It has appeared that
a small pinch of the lunar soil protects organic substances from the destructive ultraviolet
impact -- the lunar soil helps to increase the 5'-AMP yield by 2.7 times.

The researchers have made a conclusion that the organic compounds synthesis
could have happened in the outer space environment. The synthesis could have
taken place on the surface of space bodies at the initial phases of the
solar system formation, along with that the chemical evolution (formation
and selection of complex molecules) could have started in space. By the time
the Earth was formed the chemical evolution might have approached the phase
to be followed by the biological evolution. That implies that life on the
Earth most probably did not start from the elementary organic molecules
synthesis, but commenced from the polymers formation phase or from a further
stage. Hopefully, the above assumptions will help the scientists to deeper
penetrate into the mystery of the accelerated development of life on the
Earth when the latter was quite a 'young' planet.



>From Hermann Burchard <>

Dear Benny,

in Robert D. Brown's latest (Hawaii: Tombstone of the Dinosaurs", CCNet
2002-4-19), he would seem to again imply that Detroit Seamount, aged 81 Ma,
is not a portion of the Emperor-Hawaii chain but has a separate origin, as
in his AGU Spring Meeting Abstract S32A-11 (CCNet 2002-4-17) where he
promotes the idea of an "Hawaiian impact site circa 65 Ma".

By contrast, in recent work geologists Tarduno and Cottrell (U. of
Rochester, NY) appear to routinely assign the Detroit Seamount (and Meiji)
to the Emperor chain.  This is well illustrated in an abstract (see below,
Appendix 1, following my signature) from the web pages of Rory Cottrell,
paleomagnetist on ODP Leg 197, who did Ph.D. work on the motion of the
Hawaii hotspot directed by John Tarduno.  Tarduno was co-chief scientist on
ODP Leg 197.  Recent data on the geochemistry (in which I am not expert) can
be found in the Leg 197 preliminary report, 1 July-27 August 2001 (to which
Brown refers):

Extensive remarks on the hypothesis of contact at ~80 Ma between the hotspot
and a spreading ridge are included in the report (see below, Appendix 2,
beneath signature).

But there is no support in the report for Brown's idea of an "Hawaiian
impact site circa 65 Ma", or of any specific effect on the seamount chain by
events at 65 Ma.  A map included with the report

clearly shows there is complete continuity in the chain from SE of Nintoku
Seamount (56 Ma) and Suiko Seamount (65 Ma) all the way NW to the large
Detroit Seamount platform (81 Ma).  For this reason, there is no relevance
in the details shown by the NOAA close-up images of the seamounts near the
cusp of the Aleut and Kamchatka subduction trenches:

These images scarcely can lend support to Robert Brown's attempt of finding
a significant connection between an impact 65 Ma ago and the Hawai'ian
Islands.  It hardly matters whether he is right or wrong in his supposition

  "interested readers... can see for themselves that Detroit and Meiji
  ride atop a standard oceanic ridge that runs roughly parallel to and
  south of the Aleutian Chain, a reality that readily explains their
  measured isotopic composition(s)."

He is here clearly accepting the age > 80 Ma of the two mounts, but still
attempts to implies a separate origin for them.

It may be noted also that the "ridge that runs roughly parallel to and south
of the Aleutian Chain" is much different in structure in its two parts
formed by intersection with the Emperor chain: To the W of the chain the
ridge has a solid appearance and seems to be a part of the seamount chain.
This feature could be a signature of the resistance of the hotspot track to
subduction.  This resistance is easy to understand in terms of the deep
mantle roots of the track and it is also evident in, and the presumptive
cause of, the remarkable cusp formed by the two trenches at this point.

To the E of the seamounts the ridge differs and looks more ragged -- among
possible explanations this could be a part of a MOR close to the hotspot
at ~80 Ma discussed by numerous authors mentioned in the Leg 197 Report
(see quote below).

Interestingly, the NOAA images also may show the hotspot track continuing on
the Sibirian mainland in linear parallel ridges trending E-W, even on the
floor of Shelekhov gulf N of the Sea of Okhotsk.


 = = = = = = = =

Appendix 1, from Rory Cottrell's web page:

Paleolatitude of the Detroit Seamount: Implications for the Motion of the
Pacific Plate and Hawaiian Hotspot

Recent data sets available from ocean drilling have allowed a general
reconsideration of Pacific plate motion and relative motion between
hotspots. We examine here a new data set collected from Ocean Drilling
Program Site 884 (51.5o N, 168.3o E) drilled on Detroit Seamount (81 Ma)
of the Hawaiian-Emperor Seamount chain. Thirteen lithologic units, equaling
87 m of massive and pillow basalt flows, can be distinguished based on the
presence of chilled margins and changes in crystallinity. Detailed thermal
demagnetizations (50-675oC at 25o C increments) of 97 azimuthally unoriented
basalt samples were performed. Orthogonal vector plots of the thermal
demagnetization data showed near univectorial decay of most samples
analyzed. Unblocking temperatures (525-580o C) suggest that the magnetic
mineralogy has a compositional range from low Ti titanomagnetite to
magnetite. Average Hcr/Hc and Mr/Ms values, 2.51 and 0.31 respectively,
support this interpretation. Preliminary analysis of inclination-only data
suggests 9 distinct inclination groups, from which a paleolatitude of 36.3o
+/- 4.9o N was derived. Estimated angular dispersion (S) from the
inclination-only average is 16o, only slightly higher than values quoted for
rocks of this age and paleolatitude, suggesting that secular variation has
been adequately sampled. The colatitude of these basalts does not correspond
with other Campanian pole positions for the Pacific plate and apparently
contradicts prior suggestions of fast apparent polar wander between 66-81
Ma. In addition, preliminary examination of these new data suggests ~18o of
southerly offset of the Hawaiian hotspot since the formation of the Detroit

 = = = = = = =

Appendix 2,  from the TAMU Leg 197 Prelim. Report:

As an example, the Sr isotope ratios of tholeiitic basalt from the Hawaiian
hotspot track show a systematic trend through time (Fig. F6). These ratios
are approximately constant along the Hawaiian Ridge (out to the 43-Ma bend)
then decrease steadily northward along the Emperor Seamounts to Suiko
Seamount. This decrease has been attributed to a decrease in distance
between the hotspot and the nearest spreading ridge (Lanphere et al., 1980).
Only the tholeiitic basalt from the shield phase of volcano construction
show this trend because only these magmas appear
to have escaped contamination by the oceanic lithosphere (Chen and Frey,
1985). Keller et al. (2000) have extended this analysis to Detroit and Meiji
Seamounts, and they find that Sr isotope ratios continue to decrease
northward, with a minimum value at Detroit Seamount well within the range of
compositions for Pacific mid-ocean-ridge basalt (MORB). This composition
(confirmed with other isotopic and elemental ratios) is unprecedented in the
Hawaiian hotspot-produced volcanism to the south, but is consistent with the
interpretation from plate reconstructions that the
hotspot was located close to a spreading ridge at ~80 Ma. The seamount
magmas, then, appear to be derived from a mixture of plume ("enriched") and
predominantly aesthenosphere ("depleted") mantle sources. The plume
end-member is more like the "Kilauea" than the "Koolau" component of the
modern hotspot.

Plate reconstructions (e.g., Mammerickx and Sharman, 1988; Atwater, 1989)
place a spreading ridge close to the Hawaiian hotspot at ~80 Ma. In other
locations where a plume is close to a ridge (Galapagos Islands, Easter
Island, and Iceland) the isotopic compositions of hotspot products extend
toward MORB values. Several processes may lead to this effect. The nearby
spreading ridge could have provided a higher temperature and lower viscosity
and density regime, leading to significant entrainment of aesthenosphere
within the rising plume. Thinner lithosphere near the ridge would promote a
longer melting column in the plume, leading to greater degrees of partial
melting and homogenization of geochemical heterogeneities (M. Regelous et
al., unpubl. data). Also, younger, hotter lithosphere may be more readily
assimilated by the ascending plume melts.
Thus, the thickness of the lithosphere could determine how much
aesthenosphere contributes to hotspot volcanism or how possible isotopic
heterogeneities within the plume itself are expressed through partial
melting. The (deep mantle?) region where the Hawaiian plume acquires its
geochemical characteristics has probably not been homogeneous and static.
But the degree of geochemical variability at given sites within the Emperor
Seamounts has not been established on the basis of the few analyses reported
so far."


>From Bob Kobres <>

It seems that Duncan and I have an interesting dynamic concerning the term
atmosphere--I use the word in perhaps too loose (--or is that to lose?;^)  #7) of a fashion and Duncan
corrects me. This happened earlier with regard to some conjecture I was making about
events with more burn than blast:

I had originally said something like 'an oxygen enhanced atmosphere,' which
was sloppy and misleading. What I meant was a small temporary volume of
oxygen enhanced air, although I now lean more toward ball lightning type
phenomena to explain these burns. In this latest missive regarding dark
objects I intended the term atmosphere to be inclusive of anything that can
envelope Earth--sort of the opposite of how I messed up before (actually I
was conceptually including the Magnetosphere). The Exosphere is pretty far
out though and I still may have a chance to get by on the loose definition
of just how far out that sphere extends:

The point that I was really trying to make however is that we are still
pretty ignorant about how Solar System weather affects what we observe from
a terrestrial perspective--along the same line as this earlier submission
that focused upon events of 1737:  #4

In the archive I did add back the observation snippets that did not make the
mailing on the 18th:  #12

Among these is a description of an April 9, 1879, destructive fireball event
that occurred in Chicago; this may be related to the April fireball
observations described by Pavel Spurny via Jiri Borovicka's submission:  #9

There are also a couple of recently published descriptions of high energy
ball lightning, which may be more often associated with accretion events
than is currently accepted.

Also, Duncan's comments caused me to think about the following question
(from a few years back) about comet dust. I started to reply to this at the
time but never actually sent the response because I  was a bit uncertain
about my way of calculating what might happen.  Perhaps Duncan could provide
a more informed opinion on this?


>From Roy Tucker <>

At 12:32 PM 11/8/99 -0500, this was in CCNet:
[ ]

    "Actually his interpretation of the evidence is more closely
    aligned with the suggestion published by Fred Hoyle and N. Chandra
    Wickramasinghe in 1978 that the dinosaur extinction was due not to
    a cometary impact but rather to a close call. The logic is
    impeccable. The Earth is a tiny target, so for every strike there
    are thousands of close approaches.  For asteroids, only impacts
    count. But for comets, a flyby results in our planet passing
    through the cometary coma, which can be larger than the Moon's
    orbit. In such an event, we would accumulate a mass of dust, which
    takes years to settle out of the atmosphere. These crossings must
    occur on millennial time scales. (Napier and Wickramasinghe are
    currently investigating the climatic effects.)"

Dear Dr. Peiser,

The notion that the passage of the earth through a cometary coma can deposit
sufficient dust in the atmosphere to have significant environmental
consequences stretches credulity. A major volcanic eruption can introduce
many cubic kilometers of silicate particles into the atmosphere, perhaps a
volume exceeding the dimensions of the average cometary nucleus. Even if a
cometary nucleus consisted entirely of silicate dust and was totally
disrupted to fill the volume of the coma, the earth would sweep up only a tiny
fraction of this material even during a central passage.

Let's assume a twenty kilometer diameter cometary nucleus made entirely of
densely packed silicate particles with a mass of about 10^19 grams. Let us
disperse this material uniformly within a spherical volume with a diameter
equal to the moon's orbit. The density of material will be about 2 x 10^-13
grams/cubic cm. A cylindrical 'core' with a diameter equal to that of the
earth through the center of this spherical volume will contain a total of 2
x 10^16 grams of material. This equal to about 7.4 cubic kilometers of the
original comet nucleus.

Mount Pinatubo injected about 5 cubic kilometers of material into the
atmosphere and produced some beautiful twilight colors. Krakatau produced 18
cubic kilometers. Long Valley spewed 600 cubic kilometers and the
Yellowstone caldera dispersed 2000 cubic kilometers
I think a little more information is required about their hypothesis. Simple
introduction of dust into the atmosphere doesn't seem to be a compelling
argument for environmental devastation from the skies.

Best regards,
  - Roy Tucker

OK, an impact with a mass of 2x10^13 kg traveling at 30 km/sec will
(according to E = 1/2 mv^2 ) liberate 9x10^21 joules or 8.5x10^18 Btu, which
equals a bit over 14 hours of solar radiation intercepted by Earth. One ton
of TNT can release about 4.15x10^9 joules so the TNT equivalent would be
2,168,674,698,795 tons of TNT or around a 2.2 million MT event. Now the
diameter of the Moon's orbit around Earth is about 765,000 km so our planet,
traveling at 30 km/sec, takes around 25,500 seconds to move this far.  So
while Earth is traversing Roy Tucker's hypothetical comet coma it is
absorbing the equivalent of 85,046,067 tons of TNT or 85 MTs of energy per
second for 425 minutes or SEVEN hours. I would expect that this type of one
sided roasting might not be too good for the biosphere. Then of course there
is the added dust from such an encounter--not a pretty picture!

A trip through an actual comet coma that brought us close to its nucleus
would not be nearly this straight forward. The spacing of coma material,
which would include water, would decrease as the nucleus neared and then
increase upon leaving; there are also likely to be some large lumps and
clumps of comet stuff orbiting about. In addition, there is apt to be a
significant amount of organic matter within the coma soup and these carbon
combinations probably play nasty tricks with atmospheric norms.  Billions
and billions of Bucky-balls? ;^)

What we really need to learn is more about the makeup of comet nuclei and
the dynamics of the materials they shed. Volcanoes can produce a pretty
respectable mess but they aren't very good at launching stuff into
Space--most of the fall-out is local. Comets clearly have the upper
advantage in depositing slow-to-settle aerosols into the topmost layers of
Earth's atmosphere.

The total solar energy striking the earth's atmosphere is estimated to be
5.2 x 10^21 Btu/yr (EJ/y).


Bob Kobres
Main Library
University of Georgia
Athens, GA  30602

>From Ananova, 22 April 2002
A new study claims sending emails about how you feel is good for your

University students who wrote emotional emails were healthier than those who
wrote non-emotional emails or didn't send them.

Texas University psychologists say they had less time off sick then those
who didn't write emails about their feelings.

Psychologist Erin Brown says writing stops people internalising stress.

The research showed students benefited from writing about their reactions to
traumatic events like the September 11 attacks.

Prof Brown told The Daily Telegraph: "Sure, email is a fast and convenient
form of communication and even a method for proliferating corny jokes and
outrageous hoaxes. But results showed that even when administered through
email, emotional writing still produced positive health outcomes.

"People have always known that talking or writing about their problems helps
them feel better. This study provides empirical evidence that written
emotional expression is beneficial to physical health, even when conducted
through email."

Copyright 2002, Ananova

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