PLEASE NOTE:
*
CCNet DIGEST, 20 May 1998
-------------------------
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Benny J Peiser
----------------------
(1) CORRECTIONS TO "WHERE WE STAND ON THE NEO SURVEY"
David L. Rabinowitz <davidr@slam.jpl.nasa.gov>
(2) NASA SELECTS INITIAL MEMBERS OF NEW VIRTUAL ASTROBIOLOGY
INSTITUTE
Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
(3) WELL DONE, SPACEGUARD UK!
Michael Martin-Smith <martin@miff.demon.co.uk>
(4) THE INTERNATIONAL ROSETTA MISSION
M. Verdant & G.H. Schwehm, ESTEC, ESA
(5) THE EFFECT OF SHOEMAKER-LEVY 9 ON JUPITER'S MAGNETIC FIELD
F. Stabile & G. Zimbardo, UNIVERSITY OF
CALABRIA, ITALY
(6) SMALL COMETS IN THE ATMOSPHERE
Sir F Hoyle & C Wickramasinghe, UNIVERSITY
OF WALES
(7) INFRARED OBSERVATIONS OF COMETS BY COBE
C.M. Lisse et al., UNIVERSITY OF MARYLAND
(8) FRAGMENTS OF COMET HYAKUTAKE (C/1996 B2)
D.H. Chen et al., ACADEMIA SINICA
(9) DUST GRAIN FRAGMENTATION IN COMETARY PLASMA ENVIRONMENTS
Z.D. Shi et al., UNIVERSITY OF SCIENCE &
TECHNOLOGY, CHINA
============================
(1) CORRECTIONS TO "WHERE WE STAND ON THE NEO SURVEY"
From David L. Rabinowitz <davidr@slam.jpl.nasa.gov>
Hello Benny.
Please forward the attached statement to the distribution list of
the
CCNet DIGEST.
Regards.
David Rabinowitz, on behalf of the JPL/NEAT team
JPL
1998 May 19
----------------------------------
The report from David Morrison, entitled "WHERE WE STAND ON
THE NEO SURVEY" contained some rather large errors:
1) "...in February and March, 34 new NEOs were discovered,
16 of them
larger than 1 km. Of these, 21 (12 larger than
1 km) were found by
LINEAR."
These numbers are not consistent with the lists put
out by the IAU
Minor Planet Center at
"http://cfa-www.harvard.edu/iau/lists/Unusual.html"
The Minor Planet Center lists only 24 NEO
discoveries for February
and March, of which only 6 could be larger than 1 km
(i.e. have
absolute magnitudes of 18.0 or less). Of the these 6
NEOs larger
than 1 km, one (1998 FM5) was discovered by JPL's
Near Earth
Tracking Program (NEAT), two (1998 FH74 and 1998
FR11) were
discovered by the LINEAR program at MIT, one (1998
EC3) was
discovered by T. Kobayashi, and one (1998 CS1) was
discovered by J.
Zhu, Y. J. Chen, and Z. Y. Zheng at Peking
Observatory.
Al Harris points out that the numbers he reported to
Morrison were
for March and April, 1998, not February and March.
Furthermore, he
was quoting numbers for "big and small"
NEOs with "big" defined as
absolute magnitude < 19.0. This cutoff is a
magnitude fainter than
the absolute magnitude expected for 1-km asteroids.
Checking the MPC record again, I find a total of 8
NEOs with
absolute magnitudes less than 18 discovered in March
and April of
1998. Of these, 5 were discovered by LINEAR, 1 by
NEAT, 1 by
Spacewatch, and 1 by T. Kobayashi.
I should also point out that the number of
detections would be even
greater if NEAT and LINEAR were cooperating by
searching
non-overlapping areas of the sky (NEAT and
Spacewatch already have
such a cooperation). In March, NEAT re-discovered 3
of the NEOs
discovered by LINEAR, as well as the NEO discovered
by T. Kobayashi.
2) "Gene Shoemaker, who is responsible for many of the
estimates of
numbers of Earth-crossing asteroids (ECAs) and
comets, used some
special criteria to define ECAs, but roughly
these are equal to the
Apollo and Aten asteroids (currently Earth crossing)
plus a very few
of the innermost Amors (which can become
Earth-crossing). "
It is incorrect that "very few" of the
innermost Amors are
Earth-crossing (by Shoemaker's criteria). The
fraction is ~40%. To
see this, refer to the tally of ECAs published by
myself, Ted
Bowell, Gene Shoemaker, and Karri Muinonen in our
chapter in
"Hazards due to Comets and Asteroids." The
tally (Table I) lists 32
Amors (as of May 1991), whereas the total number of
known Amors in
May 1991 was 84.
David Rabinowitz, on behalf of the JPL/NEAT team
Jet Propulsion Laboratory
1998 May 19
=========================
(2) NASA SELECTS INITIAL MEMBERS OF NEW VIRTUAL ASTROBIOLOGY
INSTITUTE
From Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
Douglas Isbell/Don Savage
Headquarters, Washington,
DC
May 19, 1998
(Phone: 202/358-1547)
RELEASE: 98-84
NASA SELECTS INITIAL MEMBERS OF NEW VIRTUAL ASTROBIOLOGY
INSTITUTE
NASA has selected 11 academic and
research institutions as
the initial members of the agency's new Astrobiology Institute,
thus launching a major component of NASA's Origins Program.
The selected institutions represent the
best of 53 uniformly
first-class proposals submitted, according to NASA
officials.
Given that the institute members will remain at their home
organizations, the partnership among the members and NASA will be
carried out primarily via the Internet. This electronic
'virtual'
Institute will bring together astrophysicists, biologists,
chemists, physicists, planetologists and geologists to conduct
interdisciplinary research on the multifaceted issue of life in
the Universe and its cosmic implications. It will also help
to
train young scientists in this emerging field.
"These initial members of NASA's
Astrobiology Institute will
be at the forefront of the increasingly important link between
astronomy and biology, which has been a fundamental interest of
mine for the past several years," said NASA Administrator
Daniel S. Goldin. "The 'office hallways' of this
virtual
institute will be the fiber optic cables of the Next Generation
Internet, and the groundbreaking research that this group
generates will help guide our space exploration priorities well
into the 21st century."
The selected initial members of the Institute are:
*Universities
Harvard University, Cambridge, MA
University of California, Los Angeles
University of Colorado, Boulder
Arizona State University, Tempe
Pennsylvania State University, University Park
*Research Institutions
Carnegie Institution, Washington, DC
The Scripps Research Institute, La Jolla, CA
Woods Hole Marine Biological Laboratory, Woods Hole, MA
*NASA Centers
Ames Research Center, Moffett Field, CA
Johnson Space Center, Houston, TX
Jet Propulsion Laboratory, Pasadena, CA
NASA has developed the Origins Program
with its Office of
Space Science to search for signs of life in the Universe, both
in
our Solar System and beyond. The Astrobiology Institute
will
foster the interdisciplinary research and training necessary for
future exploration of this theme. Funding for the Institute
will
begin with $9 million in 1999 and $20 million in 2000. This
total
is expected to grow as research directions are developed and the
capabilities of the Next Generation Internet are expanded and
fully utilized.
The Astrobiology Institute members will
conduct a broad range
of interdisciplinary and synergistic research on topics
including:
the formation of organic compounds important to the origins of
life, such as from meteorites; the formation and characteristics
of habitable planets; the emergence of self-replicating systems
and possible pre-biotic worlds; how the Earth and life have
influenced each other over time, including the evolution of
ancient metabolism and the interplay of evolved oxygen; the
evolution of multicellular organisms and the evolution of complex
systems in simple animals; organisms in extreme environments such
as hydrothermal vents; and the identification and development of
biomarkers to determine terrestrial and extraterrestrial
biosignatures.
The selection of the members,
encompassing academic
institutions and government labs, was based on a competitive
evaluation process that began with the release of a Cooperative
Agreement Announcement in October 1997. The next
solicitation
opportunity for new members will take place in about a year.
For further information on the Institute
and the field of
astrobiology, see the following Internet site:
http://astrobiology.arc.nasa.gov/
The Institute's director and staff will
reside at NASA's Ames
Research Center, Moffett Field, CA. NASA Ames will manage
the
Institute's operations for NASA's offices of Space Science, Earth
Science, and Human Exploration and Development of Space at NASA
Headquarters in Washington, DC.
================================
(3) WELL DONE, SPACEGUARD UK!
From Michael Martin-Smith <martin@miff.demon.co.uk>
Jonathan, and all Spaceguard UK,
I saw the programme just now; I congratulate you, Mark Bailey,
and Tom
Gehrels; there was really a very good exposure of our case which
must
have reached many people. I know some of the other contributions
were
somewhat off the wall, but actually I think that worked in our
favour,
inasmuch it guaranteed quite a large audience- Nostradamus, like
him or
not, usually attracts attention.
I think the points that
1/ simple fragmentation of an impactor was not a good answer,
2/ that detection was feasible and really quite inexpensive,
3/ Prof Bailey's point that in due time we must step off the
planet or
become extinct (ie develop a space based civilization) came over
very
well. As you know, I am on record as making these points( 1 &
3
especially) over several years and so feel at last a sense
that the
Ideas of SpaceGuard and Space Age Associates are agreeably
converging,
and that together we are creating an Idea (evolutionary Cosmic
destiny)
whose time is almost come.
Meanwhile, the Civilian Astronauts Corps Mayflower Project is
gathering
world wide interest (Europe and Asia, as well as the USA),
a major
Press conference in Washington tomorrow, and indications of
approaching
serious sponsorship. All being well, I could ride into Space in
the
next couple of years as the first Briton to pay his own fare, and
give
Spaceguard and Space Age Associates a high ( 70 miles) profile!
An
early move towards stepping off the planet for Man the species,
not just
Man the test-pilot.
Once an Idea's time has come, as Victor Hugo says, no force of
Nature
can prevail against it. Another 10-15 years should do it! Not
long when
the stakes are so high.
Well done!
Michael Martin-Smith, Space Age Associates http://www.astronist.demon.co.uk/index.html
===============================
(4) THE INTERNATIONAL ROSETTA MISSION
M. Verdant & G.H. Schwehm: The International Rosetta Mission.
ESA
BULLETIN-EUROPEAN SPACE AGENCY, 1998, No.93, pp.39-50
ESTEC, ESA DIRECTORATE SCIENCE PROGRAMMES, SCIENCE PROJECTS
DEPARTMENT,
NOORDWIJK, NETHERLANDS
The International Rosetta Mission was approved in November 1993
by
ESA's Science Programme Committee as the Planetary Cornerstone
Mission
in ESA's long-term programme in space science, Horizon 2000. The
mission's main goal is a rendezvous with Comet 46P/Wirtanen, but
it is
also intended to study two asteroids during close flybys on route
to
the comet. Rosetta will study the nucleus of Comet Wirtanen and
its
environment in great detail for a period of nearly two years, the
near-nucleus phase starting at a heliocentric distance of about
3..25
AU, from the onset of activity through to perihelion, close to 1
AU. On
its long journey to the comet, the spacecraft will pass close to
the
asteroids Mimistrobell and Siwa or Rodari. Copyright 1998,
Institute
for Scientific Information Inc.
========================
(5) THE EFFECT OF SHOEMAKER-LEVY 9 ON JUPITER'S MAGNETIC FIELD
F. Stabile & G. Zimbardo: On the influence of the plasma
generated by
comet Shoemaker-Levy 9 on Jupiter's magnetic field. NUOVO CIMENTO
DELLA
SOCIETA ITALIANA DI FISICA C - GEOPHYSICS AND SPACE PHYSICS,
1997,
Vol.20, No.6, pp.961-966
UNIVERSITY OF CALABRIA, DEPARTMENT OF PHYSICS, I-87030 RENDE, CS,
ITALY
The impact of comet Shoemaker-Levy 9 with Jupiter has created a
variety
of magnetospheric plasmas which were detected by their
electromagnetic
emissions. By means of the Dessler-Parker-Sckopke relation we
estimate
the perturbation of Jupiter's magnetic field. It appears that the
produced plasma may explain the observed decrease of UV lines in
Io's
torus. Copyright 1998, Institute for Scientific Information Inc.
============================
(6) SMALL COMETS IN THE ATMOSPHERE
Sir F Hoyle & C Wickramasinghe*): Small comets in the high
atmosphere.
ASTROPHYSICS AND SPACE SCIENCE, 1997, Vol.253, No.1, pp.13-17
*) UNIVERSITY OF WALES, SCHOOL OF MATHEMATICS, CARDIFF CF2 4YH,
WALES,
UK
Recent claims of small icy comets disintegrating in the high
atmosphere
point to a component of comets in the form of loose aggregates of
dust.
This could be understood in terms of Lyttleton's theory of comet
formation by accretion of interstellar grains. Copyright 1998,
Institute for Scientific Information Inc.
==========================
(7) INFRARED OBSERVATIONS OF COMETS BY COBE
C.M. Lisse*), M.F. AHearn, M.G. Hauser, T. Kelsall, D.J. Lien,
S.H. Moseley, W.T. Reach, R.F. Silverberg: Infrared observations
of
comets by COBE. ASTROPHYSICAL JOURNAL, 1998, Vol.496, No.2 Pt1,
pp.971-991
*) UNIVERSITY OF MARYLAND, DEPARTMENT OF ASTRONOMY, COLLEGE PK,
MD,
20742
Comets C/Okazaki-Levy-Rudenko 1989 XX (C/OLR), C/Austin 1990 V,
(C/Austin) P/Schwassmann-Wachmann 3 1990 VIII (P/SW3), and C/Levy
1990
XX (C/Levy) were detected by the COBE/Diffuse Infrared Background
Experiment (DIRBE) with broadband photometry at 1-240 mu m
between 1989
November and 1990 September. Extended dust tails were found at 12
and
25 mu m, with detailed structure due to variations in particle
properties and mass-loss rate. Spectrophotometry of the central
42' x 42' was found to agree with that of a graybody of
temperature 1.1
times the local blackbody temperature for C/OLR and C/Austin,
while a
nongraybody distribution with a spectral index of emissivity 0.26
+/-
0.15 and temperature 1.25 times the local temperature was found
for
C/Levy. A model using modified Mie dust particles composed of
fractal
mixtures of vacuum, silicates, and carbonaceous material was
found to
fit the observations. Comparison with IUE and ground-based
observations
indicates that large dark particles of radius greater than 20 mu
m
predominate by surface area for C/OLR and C/Austin, but 1-10 mu m
particles predominate for C/Levy. The detection of P/SW3, an
optically
faint comet, was surprising, especially since four optically
brighter
comets were not detected by DIRBE. This may be related to the
nuclear
breakup observed during its next apparition. The total estimated
mass
loss from these comets in a perihelion passage is similar to 10
times
larger than that expected from optical observations, and the loss
rate
is similar to that needed to supply the interplanetary dust
cloud. No
comet trails were detected to a limiting surface brightness of 1
MJy
sr(-1), although large, beta < 5 x 10(4) particles, which
could evolve
into a dust trail, were detected in C/Austin. Copyright 1998,
Institute for Scientific Information Inc.
========================
(8) FRAGMENTS OF COMET HYAKUTAKE (C/1996 B2)
D.H. Chen*), A.D. Zhao, Q.D. Wu, Y. Song, Y.X. Fan, S.S. Sun, Y.
Zhang,
L.N. Sun: Fragments of Comet Hyakutake (C/1996 B2). CHINESE
SCIENCE
BULLETIN, 1998, Vol.43, No.2, pp.153-155
*) ACADEMIA SINICA, PURPLE MT OBSERVATORY, NANJING 210008, CHINA
Several fragments of Comet Hyakutake were observed in March and
April
of 1996. This leads to the impression that the splitting of Comet
Hyakutake on a small scale occurred frequently. Data analysis
points to
a rotation period of about 6.2 h if the fragments of April 11 are
the
condensations within a jet. Copyright 1998, Institute for
Scientific
Information Inc.
======================
(9) DUST GRAIN FRAGMENTATION IN COMETARY PLASMA ENVIRONMENTS
Z.D. Shi*), Z.Y. Li, Y. Chen: Disruption of charged dust grains
in
cometary plasma environments. CHINESE PHYSICS LETTERS, 1998,
Vol.15,
No.2, pp.155-156
*) UNIVERSITY OF SCIENCE & TECHNOLOGY CHINA, DEPARTMENT OF
EARTH &
SPACE SCIENCE, HEFEI 230026, CHINA
The equilibrium potential and dust fragmentation criterion of
fluffy
dust grains in plasma are calculated for comet P/Halley. It is
found
that the dust grain acquires its largest negative potential and
disruptive probability about 50000 km from the comet where the
dust
mass spectrum measured by the spacecraft took a great change.
Copyright
1998, Institute for Scientific Information Inc.
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