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(meteorobs) Excerpts from "CCNet, 54/2000 - 4 May 2000"
------- Forwarded Message
From: Benny J Peiser <b.j.peiser@livjm.acdot uk>
Sender: HUMBPEIS@livjm.acdot uk
To: cambridge-conference@livjm.acdot uk
Subject: CCNet, 4 May 2000 (corrected date just for the record)
Date: Thu, 4 May 2000 12:09:07 -0400 (EDT)
CCNet, 54/2000 - 4 May 2000=20
---------------------------
"A much more radical interpretation is that the molecules are=20
remains of bacteria smashed by their impact with the Stardust=20
collector. This is the view of Sir Fred Hoyle, one of Britain's=20
most eminent cosmologists, and his two collaborators, Professor=20
Chandra Wickramasinghe of Cardiff University and his brother,=20
Professor Dayal Wickramasinghe, of the Australian National=20
University in Canberra. In a paper being submitted to Astrophysics
and Space Science, they argue that a bacterial particle smashed=20
against the detectors would be largely destroyed except for=20
components of cell-wall structure with cross-linked sugars and=20
proteins. Such components, which could well have molecular masses=20
in excess of several thousand atomic mass units, would accord with
attributes claimed for interstellar dust from the
Stardust experiment,=92 they conclude."
-- Nigel Hawkes, The Times
[...]
(2) IO'S VOLCANOES SPLATTER DUST INTO THE SOLAR SYSTEM
Astronomy Now <newsalert@astronow.cix.codot uk>=20
(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 =20
WILHELMINA BRAUNSCHWEIG
[...]
(8) P/2000 G1 LINEAR
John Greaves <jgts@jgws.totalserve.codot uk>
================================================================
(2) IO'S VOLCANOES SPLATTER DUST INTO THE SOLAR SYSTEM
>From Astronomy Now <newsalert@astronow.cix.codot uk>=20
http://spaceflightnow.com/news/n0005/04joviandust/
4 May 2000
Fiery volcanoes on Jupiter's moon Io are the main source of dust=20
streams that flow from the Jupiter system into the rest of the solar=20
system, according to new findings from NASA's Galileo spacecraft=20
analyzed by an international team of scientists.=20
The scientists, led by Amara Graps of the Max Planck Institute of=20
Nuclear Physics in Heidelberg, Germany, analyzed the frequency of dust=20
impacts on Galileo's dust detector subsystem. They found peaks that=20
coincided with the periods of Io's orbit (approximately 42 hours) and=20
of Jupiter's rotation (approximately 10 hours).=20
Although dust scientists had suspected Io as the source of the dust=20
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.=20
"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.=20
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.=20
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.codot uk/news/pages/tim/2000/05/03/timfgneur02005.h=
tml
BY NIGEL HAWKES, SCIENCE EDITOR
AN ENCOUNTER far beyond Mars has given a boost to scientists who=20
believe that life on Earth may have begun in space.=20
A spacecraft has found complex carbon-based molecules drifting in the=20
solar system more than 150 million miles from Earth. They are far=20
larger than any previously discovered.=20
The results from the Stardust craft have excited scientists such as Sir =
Fred Hoyle, who has long believed that tiny extra-terrestrial life=20
forms "seeded" the planets. Other experts say that more research is=20
needed.=20
Five of the big molecules were detected between May and December last=20
year by Stardust's Cometary and Interstellar Dust Analyser. Part-icles=20
enter an intake tube at speeds of up to 18 miles per second, and strike =
an impact plate, which vaporises them.=20
"They resemble tar-like materials rather than minerals," said Dr Jochen =
Kissel of the Max Planck Institute for Extra-Terrestrial Physics in=20
Garching, near Munich, who has been helping to analyse the findings.=20
The size of the particles - up to 2,000 atomic mass units, more than=20
100 times the size of a water molecule - "surprised us as much as the=20
seeming absence of any mineral constituents. Only organic molecules can =
reach those sizes," Dr Kissel said.=20
Dr Kissel and Dr Franz Krueger report the analysis in the German=20
astronomy magazine Sterne und Weltraum. Dr Don Brownlee of the=20
University of Washington in Seattle, the principal investigator on the=20
Stardust mission, said that results were intriguing but preliminary.=20
"There is always the worry that there is some unknown about the=20
response of the instrument," he said. "But if that is the composition=20
of interstellar particles, it's very exciting."=20
Chemically, the molecules have been identified as=20
polymeric-heterocyclic aromatic compounds. The nearest terrestrial=20
equivalents are tar or coal. Dr Kissel believes that similar compounds=20
might have found their way to Earth and formed part of the "primordial=20
soup" in which life originated.=20
A much more radical interpretation is that the molecules are remains of =
bacteria smashed by their impact with the Stardust collector. This is=20
the view of Sir Fred Hoyle, one of Britain's most eminent cosmologists, =
and his two collaborators, Professor Chandra Wickramasinghe of Cardiff=20
University and his brother, Professor Dayal Wickramasinghe, of the=20
Australian National University in Canberra.=20
In a paper being submitted to Astrophysics and Space Science, they=20
argue that a bacterial particle smashed against the detectors would be=20
largely destroyed except for components of cell-wall structure with=20
cross-linked sugars and proteins. "Such components, which could well
have molecular masses in excess of several thousand atomic mass units,=20
would accord with attributes claimed for interstellar dust from the=20
Stardust experiment," they conclude.=20
The molecules also show evidence suggesting that they contain nitrogen=20
and oxygen, two elements found in living molecules but unlikely to be=20
incorporated into molecules in space by purely chemical means. "The=20
results show oxygen and nitrogen at roughly the 10 per cent level,"=20
said Professor Chandra Wickramasinghe. "That is just about the fraction =
we find in the molecules of life."=20
Copyright 2000, The Times Newspapers Ltd.=20
================================================================
(4) DUST GRAINS AROUND JUPITER
K.U. Thiessenhusen*), H. Kruger, F. Spahn, E. Grun: Dust grains around=20
Jupiter - The observations of the Galileo dust detector. ICARUS, 2000,=20
Vol.144, No.1, pp.89-98
*) UNIVERSITY OF POTSDAM,INST PHYS,POSTFACH 601553,D-14115=20
POTSDAM,GERMANY
We analyze the data of the Galileo dust detector system (DDS) with=20
respect to micrometer-sized dust grains in the inner jovian system. The =
analysis of these data requires an in-depth modeling because an exact=20
determination of the orbits of individual particles directly from the=20
data is not possible. We find that a ring of prograde particles with=20
masses between 10(-12) and 10(-11) g is compatible with the data. The=20
number density in the region around Europa's orbit is at least 4 x=20
10(-13) cm(-3). The strongest impacts observed, however, are caused by=20
a smaller population of particles in the same mass range but on=20
retrograde orbits. These particles are probably captured interplanetary =
or interstellar grains (J. E. Colwell et at. 1998, Science 280, 88),=20
Possible sources for the prograde dust are the Galilean satellites,=20
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=20
BRAUNSCHWEIG,GERMANY
Anticipating the results from the Rosetta magnetometer experiment, we=20
present a theoretical study concerning the possible origin of a=20
cometary magnetic field. Assuming the existence of a permanently=20
magnetized iron dust fraction in the primordial solar nebula, we use a=20
numerical model to investigate the outcome of a dust aggregation=20
process involving both magnetic and nonmagnetic preplanetary grains.=20
The growing dust aggregates of low fractal dimension and sizes on the=20
order of 1 mu m conserve magnetization to a large extent and could thus =
serve as building material for larger permanently magnetized celestial=20
objects. A special focus is put on deriving numerical parameters for=20
magnetic dust aggregates that can be used in subsequent numerical=20
studies. On the basis of our results, we outline possible future lines=20
of study involving the optical and mechanical properties of magnetized=20
dust, (C) 2000 Academic Press.
================================================================
* LETTERS TO THE MODERATOR *
================================================================
(8) P/2000 G1 LINEAR
>From John Greaves <jgts@jgws.totalserve.codot 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=20
recently on an informal level: since then it has had the living=20
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=20
other perihelion passage will be nearish Earth, which I'd forgot. This
leaves 1988/9 for potential perihelion passage prediscovery images,=20
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
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