PLEASE NOTE:
*
CCNet, 54/2000 - 4 May 2000
---------------------------
"A much more radical interpretation
is that the molecules are
remains of bacteria smashed by their
impact with the Stardust
collector. This is the view of Sir Fred
Hoyle, one of Britain's
most eminent cosmologists, and his two
collaborators, Professor
Chandra Wickramasinghe of Cardiff
University and his brother,
Professor Dayal Wickramasinghe, of the
Australian National
University in Canberra. In a paper being
submitted to Astrophysics
and Space Science, they argue that a
bacterial particle smashed
against the detectors would be largely
destroyed except for
components of cell-wall structure with
cross-linked sugars and
proteins. ‘Such components, which
could well have molecular masses
in excess of several thousand atomic
mass units, would accord with
attributes claimed for interstellar dust
from the
Stardust experiment,’ they
conclude."
-- Nigel Hawkes,
The Times
(1) WERE THE DINOSAURS FRIED BY ULTRAVIOLET LIGHT?
Astronomy Now, 3 May 2000
(2) IO'S VOLCANOES SPLATTER DUST INTO THE SOLAR SYSTEM
Astronomy Now <newsalert@astronow.cix.co.uk>
(3) FAR FROM HOME, HAVE WE MET OUR SMALLEST COUSIN?
The Times, 3 May 2000
(4) DUST GRAINS AROUND JUPITER
K.U. Thiessenhusen et al., UNIVERSITY OF
POTSDAM
(5) MAGNETIZED DUST IN THE SOLAR SYSTEM
H. Nubold*) & K.H. Glassmeier,TECHNISCHE
UNIVERSITAET CAROLO
WILHELMINA BRAUNSCHWEIG
(6) AUSTRALIAN 'SEARCH' EFFORTS
Duncan Steel <D.I.Steel@salford.ac.uk>
(7) NASA & SPACEGUARD
Michael Paine <mpaine@tpgi.com.au>
(8) SPACEGUARD LIMITATIONS
Duncan Steel <D.I.Steel@salford.ac.uk>
(9) P/2000 G1 LINEAR
John Greaves <jgts@jgws.totalserve.co.uk>
(10) AND FINALLY: LOSSES IN SPACE
New York Post, 2 May 2000
============
(1) WERE THE DINOSAURS FRIED BY ULTRAVIOLET LIGHT?
From Astronomy Now, 3 May 2000
http://spaceflightnow.com/news/n0005/03dinosaurs/
BY NEIL ENGLISH
Over the past few decades, the rise and fall of the dinosaurs has
captured the imagination of the public and the scientific
community
alike. While it is clear that the impact of a large asteroid
straddling
the coastline of what is the Yukatan peninsula in Mexico some 65
million years ago, may have wiped out these magnificent reptiles,
the debate still rages as to precisely how they met their demise.
Many scenarios have been suggested, including a kind of nuclear
winter
in which enormous quantities of dust were ejected into the
stratosphere, circling the globe and blotting out sunlight for
weeks
or months. But not everyone agrees that such a successful
biological
lineage as the dinosaurs could have been obliterated in this way.
Now, two American scientists - Charles Cockell of NASA's Ames
Research
Centre In California, and Andrew Blaustein of Oregon State
University,
have worked out the events that occasioned themselves immediately
after
the KT impact.
In a recent paper communicated in Ecology Letters, they explain
that
the levels of nitrogen and sulphur oxides produced during the
impact
event would have all but destroyed the ozone layer, hereby
doubling the
levels of lethal UV radiation incident on the earth's surface.
This
deluge of ionising radiation would have put additional stresses
on the
biosphere already stretched to the extreme by the impact.
What is even more remarkable though, is that significant sulphate
deposits are only found over 1 percent of the earth's surface,
rendering the KT extinction event particularly lethal for the
dinosaurs, but not for our kind - the small, furry, milk-suckling
mammals.
Copyright 2000, Astronomy Now
==============
(2) IO'S VOLCANOES SPLATTER DUST INTO THE SOLAR SYSTEM
From Astronomy Now <newsalert@astronow.cix.co.uk>
http://spaceflightnow.com/news/n0005/04joviandust/
4 May 2000
Fiery volcanoes on Jupiter's moon Io are the main source of dust
streams that flow from the Jupiter system into the rest of the
solar
system, according to new findings from NASA's Galileo spacecraft
analyzed by an international team of scientists.
The scientists, led by Amara Graps of the Max Planck Institute of
Nuclear Physics in Heidelberg, Germany, analyzed the frequency of
dust
impacts on Galileo's dust detector subsystem. They found peaks
that
coincided with the periods of Io's orbit (approximately 42 hours)
and
of Jupiter's rotation (approximately 10 hours).
Although dust scientists had suspected Io as the source of the
dust
streams, it was difficult to prove. They ruled out several
possible
sources, including Jupiter's main ring and Comet Shoemaker-Levy
9, but Jupiter's gossamer ring and Io remained as candidates. The
dust scientists studied several years of Galileo data to show
that
the motion of the dust stream particles is strongly influenced by
Jupiter's magnetic field, with a unique signature that could
exist
only if Io were the main contributor to the dust streams.
"Now, for the first time we have direct evidence that Io is
the
dominant source of the Jovian dust streams," said Graps,
lead
author of a paper on the findings that appears in the May 4 issue
of the journal Nature.
The Jovian dust streams are intense bursts of submicron-sized
particles (as small as particles of smoke) that originate in
Jupiter's
system and flow out about 290 million kilometers (180 million
miles), or twice the distance between Earth and the Sun. They
were first discovered in 1992 by the dust detector onboard the
Ulysses spacecraft during its Jupiter flyby.
FULL STORY at
http://spaceflightnow.com/news/n0005/04joviandust/
=============
(3) FAR FROM HOME, HAVE WE MET OUR SMALLEST COUSIN?
From The Times, 3 May 2000
http://www.sunday-times.co.uk/news/pages/tim/2000/05/03/timfgneur02005.html
BY NIGEL HAWKES, SCIENCE EDITOR
AN ENCOUNTER far beyond Mars has given a boost to scientists who
believe that life on Earth may have begun in space.
A spacecraft has found complex carbon-based molecules drifting in
the
solar system more than 150 million miles from Earth. They are far
larger than any previously discovered.
The results from the Stardust craft have excited scientists such
as Sir
Fred Hoyle, who has long believed that tiny extra-terrestrial
life
forms "seeded" the planets. Other experts say that more
research is
needed.
Five of the big molecules were detected between May and December
last
year by Stardust's Cometary and Interstellar Dust Analyser.
Part-icles
enter an intake tube at speeds of up to 18 miles per second, and
strike
an impact plate, which vaporises them.
"They resemble tar-like materials rather than
minerals," said Dr Jochen
Kissel of the Max Planck Institute for Extra-Terrestrial Physics
in
Garching, near Munich, who has been helping to analyse the
findings.
The size of the particles - up to 2,000 atomic mass units, more
than
100 times the size of a water molecule - "surprised us as
much as the
seeming absence of any mineral constituents. Only organic
molecules can
reach those sizes," Dr Kissel said.
Dr Kissel and Dr Franz Krueger report the analysis in the German
astronomy magazine Sterne und Weltraum. Dr Don Brownlee of the
University of Washington in Seattle, the principal investigator
on the
Stardust mission, said that results were intriguing but
preliminary.
"There is always the worry that there is some unknown about
the
response of the instrument," he said. "But if that is
the composition
of interstellar particles, it's very exciting."
Chemically, the molecules have been identified as
polymeric-heterocyclic aromatic compounds. The nearest
terrestrial
equivalents are tar or coal. Dr Kissel believes that similar
compounds
might have found their way to Earth and formed part of the
"primordial
soup" in which life originated.
A much more radical interpretation is that the molecules are
remains of
bacteria smashed by their impact with the Stardust collector.
This is
the view of Sir Fred Hoyle, one of Britain's most eminent
cosmologists,
and his two collaborators, Professor Chandra Wickramasinghe of
Cardiff
University and his brother, Professor Dayal Wickramasinghe, of
the
Australian National University in Canberra.
In a paper being submitted to Astrophysics and Space Science,
they
argue that a bacterial particle smashed against the detectors
would be
largely destroyed except for components of cell-wall structure
with
cross-linked sugars and proteins. "Such components, which
could well
have molecular masses in excess of several thousand atomic mass
units,
would accord with attributes claimed for interstellar dust from
the
Stardust experiment," they conclude.
The molecules also show evidence suggesting that they contain
nitrogen
and oxygen, two elements found in living molecules but unlikely
to be
incorporated into molecules in space by purely chemical means.
"The
results show oxygen and nitrogen at roughly the 10 per cent
level,"
said Professor Chandra Wickramasinghe. "That is just about
the fraction
we find in the molecules of life."
Copyright 2000, The Times Newspapers Ltd.
============
(4) DUST GRAINS AROUND JUPITER
K.U. Thiessenhusen*), H. Kruger, F. Spahn, E. Grun: Dust grains
around
Jupiter - The observations of the Galileo dust detector. ICARUS,
2000,
Vol.144, No.1, pp.89-98
*) UNIVERSITY OF POTSDAM,INST PHYS,POSTFACH 601553,D-14115
POTSDAM,GERMANY
We analyze the data of the Galileo dust detector system (DDS)
with
respect to micrometer-sized dust grains in the inner jovian
system. The
analysis of these data requires an in-depth modeling because an
exact
determination of the orbits of individual particles directly from
the
data is not possible. We find that a ring of prograde particles
with
masses between 10(-12) and 10(-11) g is compatible with the data.
The
number density in the region around Europa's orbit is at least 4
x
10(-13) cm(-3). The strongest impacts observed, however, are
caused by
a smaller population of particles in the same mass range but on
retrograde orbits. These particles are probably captured
interplanetary
or interstellar grains (J. E. Colwell et at. 1998, Science 280,
88),
Possible sources for the prograde dust are the Galilean
satellites,
especially Europa and Io. (C) 2000 Academic Press.
==========
(5) MAGNETIZED DUST IN THE SOLAR SYSTEM
H. Nubold*) & K.H. Glassmeier: Accretional remanence of
magnetized dust
in the solar nebula. ICARUS, 2000, Vol.144, No.1, pp.149-159
*) TECHNISCHE UNIVERSITAET CAROLO WILHELMINA BRAUNSCHWEIG,
INST GEOPHYS &
METEOROL,MENDELSSOHNSTR 3,D-38106
BRAUNSCHWEIG,GERMANY
Anticipating the results from the Rosetta magnetometer
experiment, we
present a theoretical study concerning the possible origin of a
cometary magnetic field. Assuming the existence of a permanently
magnetized iron dust fraction in the primordial solar nebula, we
use a
numerical model to investigate the outcome of a dust aggregation
process involving both magnetic and nonmagnetic preplanetary
grains.
The growing dust aggregates of low fractal dimension and sizes on
the
order of 1 mu m conserve magnetization to a large extent and
could thus
serve as building material for larger permanently magnetized
celestial
objects. A special focus is put on deriving numerical parameters
for
magnetic dust aggregates that can be used in subsequent numerical
studies. On the basis of our results, we outline possible future
lines
of study involving the optical and mechanical properties of
magnetized
dust, (C) 2000 Academic Press.
=============================
* LETTERS TO THE MODERATOR *
=============================
(6) AUSTRALIAN 'SEARCH' EFFORTS
From Duncan Steel <D.I.Steel@salford.ac.uk>
Dear Benny,
In three places in Michael Paine's article and attached
commentary
(CCNet, 3 May) there is mention of a supposed current NEO
*search*
programme in Australia. For example, it was written:
>(Rob) McNaught runs the only professional search program in
the
>southern hemisphere
Now, I am loathe to criticize, because both Rob and Michael are
doing
fantastic jobs in their own spheres; but I feel that readers
should
not be misled into believing that something is happening when in
fact
it is not. Thus perhaps an answer - as a single word or numeral -
could
be given to this question: HOW MANY EARTH-APPROACHING
ASTEROIDS HAVE BEEN *DISCOVERED* FROM SIDING SPRING
SINCE THE PREVIOUS PROJECT TERMINATED AT THE END OF 1996?
I should also note the following. Michael wrote about the NASA
goal,
adopted from the original Spaceguard Survey goal, of finding NEAs
down
to a 1 km size limit. The goalposts, however, have long since
been
moved! This is not *necessarily* the goal recognised by, say, The
Spaceguard Foundation. In fact the Council of Europe resolution
of 1996
dropped the target size to 0.5 km. As that means four times less
bright, as a rule of thumb, the telescopic requirements are
entirely
different to what Michael addresses in his discussion. Indeed the
target size advocated by others is even smaller. I have recently
heard
that the Decadal Review (of astronomical facilities) in the US
may be
recommending the building of a very large (8-m aperture)
wide-field
search system, to cover the northern sky on a weekly basis. That
would
be phenomenal. The stated target size for NEAs is 300 metres.
Even that
is not small enough for some people. Not only have the goalposts
been moved, but they are very mobile.
Kind regards,
Duncan Steel
==============
(7) NASA & SPACEGUARD
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
Duncan Steel has mentioned the moving goalposts of Spaceguard. I
alluded to this in my article with the sentence 'Debate continues
over
the risk from these other objects...'. I have realised, however,
that
an important comment from Don Yeomans was edited out of my
article:
"...the NASA plan is to use ground-based facilities to
discover 90% of
the large NEAs (D>1km) within ten years. This search
effort will also
capture many of the smaller NEAs and comets of course but as Al
[Harris]
noted, to try to discover the majority of small 100-m sized NEAs
would
be an extraordinary, and frightfully expensive, effort. The
current
plan is to find the big ones first, then as the detection
technology
improves, extend the search to smaller and smaller objects."
It is a matter of priorities. The 1km+ search should also
quantify the
threat from smaller objects and this should help justify the more
expensive systems needed to detect a significant proportion of
them. As
you raised in your AAAS talk, impacts by small NEOs tend to not
leave
much evidence at the Earth's surface and are difficult to
identify in
historical records. Without such evidence, or a good sampling of
the NEO
population, it will probably be difficult to convince politicians
to
spend the larger amounts on detection systems for small NEOs. Of
course
a sudden impact with local but devastating consequences might
change all
of that - based on John Lewis's simulation software, the odds of
such an
event over the next decade are roughly 1 in 9 with an average of
120,000
fatalities! (see http://www1.tpgi.com.au/users/tps-seti/sta1047.htm
)
regards
Michael Paine
=============
(7) SPACEGUARD LIMITATIONS
Duncan Steel <D.I.Steel@salford.ac.uk>
Number of NEAs discovered from Siding Spring since the end of
1996 = ZERO. That should not be covered up by writing about an
Australian *search* programme. Either there is no search
programme, or
else there is one and it has zero effectiveness. Follow-up is
laudable,
essential. But the public should not be conned.
On the topic of the Spaceguard 'goals', it's not just the size
limit
which has been shifted. The 'NASA Spaceguard Goal' also drops the
'completeness factor' to incompleteness: 90% discovery level.
That
makes a huge difference. If you originally wanted 99% but you
drop to
90%, then it leaves ten times more objects undiscovered. Michael
Paine's article may give the impression to some that enhanced
technology between 1992 (original Spaceguard Survey report) and
now has
led to 1-m telescopes being able to do what 2.5-m telescopes
could do a
decade ago. (And from that it would follow that governments were
correct not to invest in 2.5-m systems back then.) That is false,
indeed contrary to the laws of physics: detectors cannot have
quantum
efficiencies of more than unity. The limitation is on how many
photons
one collects & detects. The place that the finagling has
occurred here
is by dropping the completeness factor from 0.99+ down to 0.9,
thus
allowing the NEAs which are difficult targets (say, being at
aphelion
at all prospective discovery epochs over the next two decades,
hence
faint) to be dismissed. This goalpost shifting was forced by a
political decision to drop the timescale from the Spaceguard
Survey
plan of a 20-25 year programme down to 10 years. As I have said
previously, some politicians believe that the laws of economics
can
overcome the laws of nature/physics.
There is nothing wrong with shifting the goalposts: but the story
must
be consistent with reality, else the public is being deceived.
Duncan Steel
==============
(8) P/2000 G1 LINEAR
From John Greaves <jgts@jgws.totalserve.co.uk>
Dear Benny Peiser
re P/2000 G1 LINEAR and possible meteors 'article' on CCNet
3/5/00
i) I originally wrote the note that has been forwarded to CCNet
recently on an informal level: since then it has had the living
daylights forwarded out of it, something I did not even remotely
expect
at the time of writing.
ii) It is highly unlikely that any 1994 perihelion passage
pre-discovery
images will be found, the object was probably near superior
conjunction
at that perihelion passage. The 5.4 year period means that only
every
other perihelion passage will be nearish Earth, which I'd forgot.
This
leaves 1988/9 for potential perihelion passage prediscovery
images,
only, due to orbit probably being different pre 1987 Jovian
encounter.
iii) It is only a ten day orbital arc that I have been playing
with. I'm
not sure how reliable extrapolating beyond Jovian encounters is,
either. However, note that so far no significant similarities
between
previous orbits and IAUC photographic meteor orbits' database
have been
found via Drummond's D' criterion.
iv) Indeed, the ascending node seems to have been evolving
continuously
up until recently, and perihelion distance oscillating. The
best
potential for any showers is between 2003 and 2027, when
ascending node
and perihelion are hopefully going to be quite stable.
v) If the orbital evolution does pan out, and no meteor shower
occurs, I
hope professional scientists will put as much effort into saying
why no
shower did occur as they currently appear to do in connecting
every hole
in the ground with the disappearance of major faunal taxa. The
recent
thrashing about that occured with people looking for extinction
events
in the geologic record that fell within the 100+ million year
probable
landfall window of the newly discovered underground astrobleme in
Australia was a tad worrying. I thought it was supposed to be
cause and
effect, not effect and cause...
Cheers
John
John Greaves
UK
=============
(9) AND FINALLY: LOSSES IN SPACE
From New York Post, May 2, 2000
http://www.nypost.com/gossip/pagesix.htm
NO wonder Lou Dobbs was exploring the possibility of going back
to his
mothership, CNN - his space venture doesn't seem to be working
out so
well. Sources say that at the end of the financial quarter this
March,
space.com had revenues of only $206,830 and an astounding
$3,877,844 in
expenses - 28 percent more than expected. This on the heels of an
employee exodus as the company has been generous with stock
options but
not so magnanimous with actual paychecks. A rep for the company
said,
"Space.com is a private company that doesn't release its
financial
figures. No comment."
MODERATOR’S NOTE: According to my own figures for the same
period,
CCNet had revenues of only $0,00 and an astounding $0,00 in
expenses -
just as insiders expected. Yet CCNet subscription numbers (800+)
are
steadily increasing. What is more, the only Exodus reported on
CCNet
was the catastrophe-ridden one out of Egypt while staff (N=1)
statisfaction remains excellent and persisting.
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