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(meteorobs) Excerpts from "CCNet 20/2002 - 8 February 2002"
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From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet: AUSTRALIA FAILS WORLD ON ASTEROIDS
Date: Fri, 8 Feb 2002 15:55:28 -0000
CCNet 20/2002 - 8 February 2002
-------------------------------
[...]
(3) COMETS GET A SNOWBALL'S CHANCE
The Guardian, 6 February 2002
[...]
(5) METEORS GO POP IN THE NIGHT
Ron Baalke <baalke@jpl.nasadot gov>
(6) RECORDING OF MYSTERIOUS METEOR SOUNDS
Andrew Yee <ayee@nova.astro.utorontodot ca>
(7) NASA'S COMET TOUR CHALLENGES TEACHERS & STUDENTS TO ENTER CONTEST
Ron Baalke <baalke@jpl.nasadot gov>
[...]
(9) COMETS II BOOK: CALL FOR CHAPTERS AND PARTICIPANTS
Gerhard Hahn <gerhard.hahn@dlrdot de>
[...]
(12) METEORITE HUNTER: SPACE.COM INTERVIEW WITH ROY A GALLANT
Space.com, 7 February 2002
==============
(3) COMETS GET A SNOWBALL'S CHANCE
>From The Guardian, 6 February 2002
http://www.guardian.codot uk
A stream of comets is falling into the sun, writes Duncan Steel
Duncan Steel
Theory and observation go hand in hand in science. Until recently we were
limited to a theoretical evaluation of just what is a snowball's chance in
hell. But now we have experimental verification. As expected, the chance is
essentially zilch.
Comets are snowballs. Dirty ones, with rock and organic chemicals mixed in,
but snowballs none the less. And hell, one imagines, is much like the sun's
surface. With a temperature near 6,000 C, it's more than red-hot.
Comets have a major obstacle to pass before they can plunge into the sun.
Surrounding our local star is the corona, the multimillion-degree solar
atmosphere that can only be seen during an eclipse, which occurs rarely.
Satellite studies of the corona have enabled astronomers to see a multi tude
of comets make their death plunge.
To better understand the solar atmosphere and its effect on the terrestrial
environment we need continuous monitoring.
The solution is obvious, though costly. Produce an artificial eclipse using
a satellite-borne telescope and a black disk to occult the sun. Several
instruments of this type have flown, one of the most successful being Soho
(the solar and heliospheric observatory), a joint project of ESA and Nasa.
In the Soho image pictured, the large dark area straddling the centre
results from the obscuring disk. The white circle inside it indicates the
size of the sun. Several bright regions are seen around the disk's
periphery, showing outward gas flows in the corona.
But there is also an obvious bright streak at the lower right. This is a
small comet. Successive satellite images, obtained in October, showed it to
be falling into the solar furnace. Almost 400 comets have been
identified using Soho. Although it is operated by professional teams, they
are mostly interested in solar physics. This means that many comets pass
unnoticed and remain in archives for years before amateurs identify possible
comets.
Champion among these is Michael Oates, a member of the Manchester
Astronomical Society. He has found well over a hundred comets in Soho
images. Although Soho detects some comets near the sun that will turn around
and pass outwards again most are seen in their death throes. Many are so
small, not much bigger than a house, that they hardly deserve to be called
comets. They produce a detectable trail because as the intense solar
radiation causes their constituent ice to evaporate, dust is released,
which scatters sunlight.
These tiny comets, often called sungrazers, are interesting because the
majority seem to follow almost the same path. That is, they appear to be
fragments of a much larger comet that broke apart millennia ago.
We saw the same sort of thing happen, on a smaller scale, a few years ago.
Comet Shoemaker-Levy 9 was found in orbit around Jupiter, apparently having
broken apart in 1992, just before its discovery, when it flew too close to
the planet. By the time of the collision with Jupiter in July 1994, its
20-odd major fragments had separated sufficiently for the fireworks to
continue for more than a week.
With sungrazer comets, the spreading is much greater. In the late 19th
century, Heinrich Kreutz, working in Kiel, Germany, noted the orbital
similarity of several bright comets observed in the preceding decades. They
became known as the Kreutz group, but until Soho entered operation at the
end of 1995 it was never suspected how many individual members the complex
might contain. There are certainly tens of thousands to be found, and the
parent of the swarm must have been a behemoth, more than a hundred
kilometres in size and so over a thousand times the mass of Comet Halley.
The history of the Kreutz parent breakup is gradually being pieced together.
To explain the fragment dispersion, a time scale of at least 10,000 years is
required, but there have been subsequent disintegration events. In 372 BC
the Greek astronomer Ephorus saw a bright comet break asunder. One of its
two daughters seems to have been observed again about every 350 years since,
the other taking 700 years.
Each time subsidiary splits have taken place, the stream of debris has built
up. But why do comets split? Some fall apart for no apparent reason.
Shoemaker-Levy 9 was torn into pieces by the tidal force of Jupiter's
gravity when it strayed too close. But what causes them to fall apart is
apparently thermal stress. As each split occurs, more of the ice is exposed,
and the fragments get smaller until on the next visit they vaporise. Giant
comets such as the Kreutz progenitor exist, and when they split, they leave
myriad smaller bodies zipping through space, each potentially lethal.
Although the Kreutz comets have orbits crossing that of the Earth, their
orientation is such that they consistently miss us. Just as well, else these
snowballs would be giving us hell.
Copyright 2002, Guardian Newspapers Limited
===========
(5) METEORS GO POP IN THE NIGHT
>From Ron Baalke <baalke@jpl.nasadot gov>
http://www.nature.com/nsu/020204/020204-3.html
Meteors go pop in the night
Recordings of sounds from shooting stars defy explanation.
Nature Science Update
Philip Ball
February 6, 2002
Scientists camping out in the Mongolian snow at minus 30 degrees C have made
the first recordings of an elusive sound: the crackle and pop of a meteor
shower[1]. Their observations defy all current explanations of what happens
when debris burns up on entry to the Earth's atmosphere.
Some meteor booms are simply acoustic waves like those from supersonic
aircraft. But for centuries there have been rumours of more baffling
'electrophonic' noises occurring at the same time as meteors become visible.
Because light travels much faster than sound, there should be a delay
between the appearance of a meteor and its sound - just as thunder generally
comes seconds after a lightning flash. In fact, meteors burn up so high in
the atmosphere that this time delay ought to be a few minutes.
Because one of the leading candidate theories is that electrically charged
particles streaming behind meteors interact with the Earth's magnetic field
and produce radio waves, which cause the electrophonic noises. These radio
waves are broadcast to an observer at the speed of light. They could be
converted to sound by exciting vibrations in objects at ground level.
Full story here:
http://www.nature.com/nsu/020204/020204-3.html
============
(6) RECORDING OF MYSTERIOUS METEOR SOUNDS
>From Andrew Yee <ayee@nova.astro.utorontodot ca>
International Leonid Watch - Croatia
Contacts:
For ILWC:
Slaven Garaj
Department of Physics
Swiss Federal Institute of Technology Lausanne
E-Mail: slaven.garaj@epfl.ch
Tel.: +41 21 693 4461
http://fizika.org/ilwcro
For GEFS:
Dejan Vinkovic
Department of Physics and Astronomy
University of Kentucky
E-Mail: dejan@ccsdot ukydot edu
Tel.: +1 859 257-8741
http://gefs.ccsdot ukydot edu
For immediate release: January 20, 2002
Recording of mysterious meteor sounds
Joined by the International Leonid Watch - Croatia (ILWC) project, a group
of scientists presented the first instrumental detection of elusive
electrophonic meteor sounds. In November 1998, the researchers from the
Croatian Physical Society and the University of Kentucky organized an
expedition to Mongolia to observe the anticipated Leonid meteor shower and
shed some light on the phenomenon. The complete data analysis revealed two
electrophonic sounds that provided several important clues about the nature
of this longstanding astronomical mystery.
In the year 1676, Geminian Montanari from Italy realized that the normal
sounds produced by a bright fireball require several minutes to reach the
ground. The same is true when thunder lags behind distant lighting. However,
the mystery was born when he noticed that some people claimed they heard
sounds simultaneously with the meteor.
It was not until 1980 that the electrophonic sounds had their revival in the
work by Colin S. L. Keay. Intrigued by these sounds, he proposed that
meteors could produce very low frequency (VLF) electromagnetic waves. These
radio waves travel with the speed of light, thus reach an observer almost
simultaneously with the appearance of the meteor. Then they make a sound by
simply vibrating an ordinary object.
However, something was missing in this picture. The Leonid meteors are very
fragile and burn out too high in the atmosphere, contradicting the Keay's
physical model of VLF meteor emission. Nevertheless, a spectacular Leonid
storm of 1833 yielded a list of electrophonic sound reports. These reports
and anticipated large number of meteors indicated that the 1998 Leonids were
a good target for the ILWC
project.
The expedition site was far from populated area to avoid radio and audio
noise. Environmental conditions were harsh, with temperatures as low as -30
C (-22 F). The meteor shower appeared and numerous bright meteors
illuminated the snow covered Mongolian plane. The experiment included a
video camera, VLF radio receivers, and microphones acoustically isolated
from the observers.
Two fireballs produced a short duration "pop"-like sound, with one of them
captured on video. The sounds resemble deep "pops" reported in 1833, but the
analysis of all collected data revealed surprises. Damir Kovacic from the
Cognitive Neuroscience Sector at SISSA, Trieste, Italy, coordinated the
sound detection experiment. "First of all, finally we have a strong
indication that our electrophones were indeed produced by the
electromagnetic radiation", he says, "but it is rather of much lower
frequency than expected."
The picture had become even more blurred when the theoretical analysis was
applied to the data. "There are two major theories, including the one by
Keay, about the physical process of radio
emission from meteors. Both of them failed to explain the data", says Dejan
Vinkovic, a member of the team and coordinator of the Global Electrophonic
Fireball Survey (GEFS) at the University of Kentucky. "Basically, we are
back to the drawing board, where we have to start thinking about refining
the theory for Leonids."
There are some important clues, though. "It is interesting to notice that
both electrophonic sounds were created when the meteors were crossing the
border of the nighttime ionosphere, a layer of charged particles", says the
project leader Slaven Garaj from the Swiss Federal Institute of Technology
Lausanne. "Also, the energy of meteor may not be sufficient to invoke large
electric fields needed to produce electrophonic sounds. Thus, a strong
coupling of a meteor
with the ionosphere has to be taken in account in any future theory."
The paper about these results will appear in the Journal of Geophysical
Research. Other members of the team are Goran Zgrablic and Neven Grbac
(University of Zagreb, Croatia), Silvija Gradecak (Swiss Federal Institute
of Technology Lausanne), Nikola Biliskov and Zeljko Andreic (Rudjer Boskovic
Institute, Croatia).
After the expedition to Mongolia, the team initiated the GEFS project with
the goal of collecting witness reports of electrophonic sounds and
coordinating future experiments. There are many new reports about
electrophonic sounds from the recent 2001 Leonids this November. If you have
heard an electrophonic sound, please send a report to the GEFS project at
the web-address:
http://gefs.ccsdot ukydot edu
Images, videos and additional information are available at the project's web
site:
http://fizika.org/ilwcro/results/index.html
===========
(7) NASA'S COMET TOUR CHALLENGES TEACHERS & STUDENTS TO ENTER CONTEST
>From Ron Baalke <baalke@jpl.nasadot gov>
http://www.news.cornelldot edu/releases/Feb02/contour.contestdot deb.html
NASA's comet tour challenges teachers and students to enter contest
FOR RELEASE: Feb. 5, 2002
Contact: David Brand
Office: 607-255-3651
E-mail: deb27@cornelldot edu
ITHACA, N.Y. -- NASA's Contour space mission and Cornell University are
challenging students and their teachers in the United States to participate
in the spacecraft's forthcoming exploration of comets.
They are being invited to participate in the Cornell and Contour Comet
Challenge, with the grand prize for the winners a trip to Kennedy Space
Center at Cape Canaveral Spaceport, Florida, to witness the launch of the
spacecraft scheduled for July 1. The NASA mission, officially the Comet
Nucleus Tour, is being managed by the Applied Physics Laboratory at the
Johns Hopkins University, with Cornell's Department of Astronomy leading the
international science team.
As part of Cornell's educational outreach for the mission, students and
their teachers are being challenged to devise a program to educate and
involve their communities about Contour's goal to study at least two comets
as they travel through the inner solar system. The spacecraft will provide
the closest look ever at a comet's nucleus.
The teams submitting the two winning programs -- one in grades 5 through 8
and one in grades 9 through 12 -- will be invited to attend four days of
launch-related activities, including interviews with mission scientists and
engineers, at Kennedy Space Center. Each team will be allowed a budget of
up to $1,000 for its educational program. The winning teams, each consisting
of a teacher and a student, will be chosen by a panel of educators and
scientists on the basis of the originality and feasibility of the submitted
plans.
Students don't need a lot of background knowledge either on Contour or about
comets to participate in the program, explains Laura Lautz, the mission's
education and public outreach coordinator at Cornell. "The key is, they need
to be curious," she says. Beyond that, the
teachers and students can develop any kind of presentation they choose: a
program in conjunction with a local museum, a web-based program or even a
video. Students will be encouraged to speak in public and to write articles
for local or student newspapers. As well as the two winning teams, two
teams from each state will be chosen to receive a kit of Contour materials
so that they can follow through with their plans to share the mission's
comet exploration with their communities. These teams also will be able to
watch the launch on their computers via Web streaming, and to ask questions
of mission scientists following the launch. For more information on the
space mission and how to enter the competition, go on line to
http://www.contour2002.org
Related World Wide Web sites: The following sites provide additional
information on this news release. Some might not be part of the Cornell
University community, and Cornell has no control over their content or
availability.
o Cornell Department of Astronomy: http://astrosun.tn.cornelldot edu
o NASA Discovery Program: http://discovery.nasadot gov
============
(9) COMETS II BOOK: CALL FOR CHAPTERS AND PARTICIPANTS
>From Gerhard Hahn <gerhard.hahn@dlrdot de>
On behalf of the editors of the COMETS II Book we distribute the following
CALL FOR CHAPTERS AND PARTICIPANTS
Gerhard Hahn
LOC ACM2002
PS.: The second announcement for the Asteroids, Comets, Meteors 2002
Conference (ACM2002) will be made shortly.
- ---------
COMETS II
CALL FOR CHAPTERS AND PARTICIPANTS
- ------------------------------------------------------------------------
Response must by received by February 10, 2002
- ------------------------------------------------------------------------
Dear Colleagues,
Since the publication in 1982 of the Space Science Series Book "Comets",
there have been dramatic advances in cometary science. Spacecraft have
visited four comets, and the IR and millimeter ranges have been
systematically explored revealing a wealth of new molecular species.
Hundreds of transneptuniam objects, which are the likely progenitors of the
short-period comets, have been discovered during the past decade. A new era
is now opening during which coma samples will be studied with spaceborne and
ground-based instruments. Hardware advances will continue to deliver
new remote-sensing results at an increasingly rapid pace. In addition,
theoretical advances and new computational resources allow complex systems
to be modeled more accurately than before, thus providing a much clearer
understanding of processes such as coma structure and evolution, nucleus
activity, coma and solar system nebula physics and chemistry, and orbital
dynamics.
For these reasons, the time has come to begin work on "Comets II", a new
book to be published in the Space Science Series of the University of
Arizona Press. A Scientific Organizing Committee (SOC) of 16 international
members has been formed and has made plans for the organization and content
of this book. The editors of Comets II will be Michel C. Festou, H. Uwe
Keller, and Harold A. Weaver.
The purpose of this message, sent on behalf of the Editors and the SOC, is
to invite you to participate in the Comets II project. More specifically,
this message is a solicitation of ideas for chapter topics and a
solicitation of volunteers for chapter authors. If you would like to
recommend chapters for the book or would like to volunteer to write a
particular chapter, we would like to hear from you NO LATER THAN February
10, 2002.
We hope that you will consider contributing to this effort, as we expect
Comets II to be the fundamental source of information on comets for both
students and researchers during the next decade.
A detailed information notice for Comets II chapter authors and contributors
is available at:
http://webast.ast.obs-mip.fr/people/festou/comets2_information_notice.html
If you do not anticipate being an author, please consider serving as a
reviewer and complete the attached form. If you have any questions, you can
direct them to the editors using the contact information supplied in the
information notice.
PLEASE NOTE AGAIN THAT THE DEADLINE FOR RESPONDING TO THIS SOLICITATION IS
FEBRUARY 10, 2002.
Thanks in advance for your cooperation.
Dr. Richard Binzel University of Arizona Space Science Series Director
==========================
LETTERS TO THE MODERATOR *
==========================
(12) METEORITE HUNTER: SPACE.COM INTERVIEW WITH ROY A GALLANT
>From Space.com, 7 February 2002
http://www.space.com/spacelibrary/books/library_gallant_020208.html
Meteorite Hunter: The Search for Siberian Meteorite Craters
by Roy A. Gallant
For the last ten years Prof. Roy A. Gallant has been digging around the
notoriously treacherous Siberian wastelands so (thankfully!) you and I don't
have to.
His mission: To uncover the mystery surrounding what's known today as the
Tunguska Event, the 1908 meteorite impact that was so great it exploded with
a force 2000 times the size of the Hiroshima blast, its shockwave circling
the earth twice.
But what was the object? A comet's nucleus? Or a stony asteroid? Braving the
region's natural predators (from bears to blood-thirsty bugs), Gallant,
using research never before seen outside Russia, attempts to find answers in
a book that is part history, part travelogue and part scientific inquiry.
SPACE.com: What's more dangerous, Siberian mosquitoes or rocks from space?
Roy A. Gallant: I'll take the mosquitoes. At least you can hit back.
Q: Because the 1908 meteor exploded aboveground, little is known about the
object. What new insights can you give us? Was it a comet or an asteroid?
A: Not really any new insights into the cause of the event, more a matter of
accumulating evidence tending to support the notion that the exploding
object was a comet nucleus. This is the collective opinion of most Russian
investigators; although some say they cannot confidently rule out a stony
asteroid. Although computer modeling can be helpful, it is not a reliable
substitute for the types of field investigations I report in my book.
Q: Based on your research, what did the event look like to an observer
standing at a (barely) safe distance?
A: There was blinding light from the explosion--violent flash accompanied by
an extremelhy hot and violent wind, and there was a pressure wave strong
enough to knock people down. Add to that thunderous noise sounding like
batteries of artillery fire. Than the expansive forest burst into flame.
Many close to the blast were temporarily deafened, struck dumb and
speechless, and fell to the ground in a state of shock.
Q: What would happen if a similar event occurred over a metropolitan region?
A: If there had been a difference of one hour when the Tunguska object
struck, it would have exploded over St. Petersburg and killed about 500,000
people.
Q: Experts agree it's only a matter of time before a much larger object hits
the planet. How worried are you about the survival of civilization?
A: I'm not at all worried since there's nothing I or any one else can do
(sic!) to prevent a planet-crunching asteroid a few kilometers in diameter
from largely destroying the civilized world. It's a numbers game. We simply
have no way of knowing when we'll be hit again. You read a lot of
numbers--certain size asteroids striking Earth every 1000 or 50,000 or
500,000 years. If we haven't been hit for a long time, does that mean we are
likely to be hit soon? Not necessarily. Any one versed in probability theory
can tell you that the past occurrence of the sum of seven turning up on the
next dice toss has nohing whatever to do with the number of times seven has
shown up in the previous 20 or so tosses.
Q: Who are your heroes and how have they influenced your work?
A: I have many heroes in science, among them Charles Darwin and others like
him who devoted a great part of their lives nurturing a old hypothesis and
watching it evolve into theory, and eventually gain the status of scientific
principle, all through theie tireless and methodical collection of evidence.
But science tends not to be down that way any more. Just turn to the title
page of mose major articles in the journals NATURE and SCIENCE and see the
multiple by-lines, sometimes up to a dozen or so investigators. The new
technologies in biology and physics, for example, are making a rarity out of
the potential Darwins or a Copernicus.
Q: What most upsets you about science or scientists?
A: There's nothing about science as a means of investigating the natural
world that upsets me, even though a scientists' search for truth is bound to
step on toes every now and then. For the most part, I think scientists are a
pretty honest lot with well defined goals. The scientists who do not fit
that pattern are those who have sold out to the tobacco, nuclear, and
certain other industries that try to convince us that their product or
activity is perfectly safe, when they know just the opposite is true.
Q: If you controlled a $1 billion foundation, what research effort would you
fund?
A: Since a billion dollars isn't all that much money these days, I'd look
for a relatively modest research effort, perhaps one directed more toward
education rather than expensive hardware that might teach us how to mine an
asteroid. In the field of astronomy, perhaps an effort to identify the
misconceptions young people hae about basic astronomy, space, space travel,
the nature and probability of life elsewhere in the universe and the
philosophical implicatioins of its discovery. The second, and major, part of
my program would be the preparation, publication, and distribution of
educational materials at the junior high and up levels. Such materials would
be relatively inexpensive, and their funds generated would go back into the
program to make it largely self-sustaining.
Q: Why should we spend money on space exploration over research into deadly
diseases?
A: I see no reason why we shouldn't be doing both at the same time.
Q: What is the most beautiful aspect to space?
A: Its silence and profoundly humbling aspect.
Copyright 2002, Space.com
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