PLEASE NOTE:
*
CCNet, 22/2000 - 17 February 2000
---------------------------------
QUOTE OF THE DAY
"Innumerable suns exist;
innumerable earths revolve
around these suns in a manner similar to
the way the
seven planets revolve around our sun.
Living beings
inhabit these worlds.”
-- Giordano Bruno, On
the Infinite Universe and Worlds,
published in 1584
"Together with two other respected
astrophysicists Hoyle
systematically reviews the evidence for
the Big Bang theory, and
gives it a good kicking. Even if you don’t
buy into their claims
for the Steady State theory (and you'll
need to be comfortable
with advanced mathematics even to make a
down-payment), it's hard
not to be the impressed by the audacity
of the demolition job.
[...] I don't expect the vast majority
of astronomers to pay the
slightest attention to Hoyle and his
colleagues: frankly, there
are too many careers riding on the Big
Bang being right.
Even so, I can only hope that I possess
one-thousandth of Hoyle’s
fighting spirit when I, like him, have
reached my 85th year."
-- Robert
Matthews on Sir Fred Hoyle
(1) FIRST UV OBSERVATIONS OF A METEOR IN SPACE
Ron Baalke <baalke@jpl.nasa.gov>
(2) HOW THE MOON FOUND ITS ORBIT
Andrew Yee <ayee@nova.astro.utoronto.ca>
(3) NASA BEGINS BUILDING NEXT MISSION TO STUDY COMETS
NASANews@hq.nasa.gov
(4) SIR ARTHUR ENVISIONS WORLDWIDE WARNING SYSTEM
Space.com, 16 February 2000
(5) 400th ANNIVERSARY OF THE BURNING OF GIORDANO BRUNO
Larry Klaes <lklaes@bbn.com>
(6) SIR FRED RETURNS TO GIVE BIG BANG ANOTHER KICKING
[thank God Fred didn’t live 400 years
ago!]
The Sunday Telegraph, 13 February 2000
(7) RADAR OBSERVATIONS OF COMETS
J.K. Harmon et al., ARECIBO OBSERVATORY
(8) METEOROID STREAMS AT MARS
A.A. Christou & K. Beurle, UNIVERSITY OF
LONDON
(9) RESONANT ORBITS AND SMALL NEOS
Michael Paine <mpaine@tpgi.com.au>
(10) DEFENDING EARTH: ONE COMMENT & A QUESTION
John Richfield <jonr@iafrica.com>
(11) HOW HARD IS EROS?
Mayo Greenberg <greenber@strw.leidenuniv.nl>
(12) AND FINALLY: STUDY FINDS HEAVY NET USERS ISOLATED
[a timely reminder for some overworked
NEO researchers .....:-)]
MSNBC, 15 February 2000
======================
(1) FIRST UV OBSERVATIONS OF A METEOR IN SPACE
From Ron Baalke <baalke@jpl.nasa.gov>
Public Affairs Office
Naval Research Laboratory
Washington, D.C.
February 9, 2000
NRL Press Release 9-00r
NRL Instrument Makes First UV Observation of Meteor in Space
Scientists from the Naval Research Laboratory (NRL) report that
the
first ever far-ultraviolet (UV) image of a meteor has been
obtained by
the Global Imaging Monitor of the Ionosphere (GIMI) instrument on
board
the DoD Space Test Program's Advanced Research and Global
Observation
Satellite (ARGOS). The image was taken on November 18, 1999,
during the
annual Leonid maximum, which in 1999, lasted from November 16 -
18.
At the time of the exposure, the ARGOS spacecraft was about 20
deg
south of the equator, over the south Pacific Ocean; however, the
viewing direction (and the ARGOS altitude of 833 km) was such
that the
meteor itself was much closer to the equator.
Dr. George Carruthers, NRL's GIMI principal investigator, reports
the
scientific significance of the observation, saying, "To our
knowledge,
this is the first observation of a meteor entry to the atmosphere
in
the far-UV spectral range. Such an entry cannot be observed from
Earth's surface or from aircraft because of its absorption by the
lower
atmosphere. Ground-based observations of meteors cannot detect
many of
the important elements and compounds expected to be present in
meteoroids."
"The first observation from space of a meteor, by GIMI in UV
light,
adds another dimension to the handful of previous space
observations of
meteors," notes Dr. Noah Brosch of the Wise Observatory and
the
Department of Astronomy and Astrophysics at Tel Aviv University
in
Israel. Dr. Brosch explains, "Satellites view the Earth
continuously
and rarely detect extremely bright fireballs. These detections
are
mostly in the visible or near-infrared spectral domains. The GIMI
observation is the first such space experiment to be done in the
UV."
Commenting on the practical application of this discovery,
Brigadier
General (sel) S. Pete Worden, USAF Deputy Director for Command
and
Control says, "As our civil, commercial and national
security use of
space continues to increase, natural phenomena that can disrupt
satellite operations cause growing concern. The Leonid meteor
storm is
such a phenomenon. NRL's impressive data promises to provide a
unique
new tool to understand the true composition and structure of
these
meteors. This is vital information if we are to predict and
mitigate
future meteor-induced problems to our space operations."
Abundances of various elements and compounds found in meteors are
known
to be highly variable among the types of meteorites which have
been
recovered on the ground, but the latter are not representative of
the
range of meteoroids as expected to be present in the solar
system, since
only the most refractory and/or massive meteoroids survive entry
to the
atmosphere. Once we have an opportunity to analyze our data and
examine
other images for events of this type, says Carruthers, we may
establish
the feasibility of using far-UV spectroscopic instruments to more
accurately measure the compositions of incoming meteoroids.
Because Earth's lower atmosphere strongly absorbs far-UV
radiation in
the wavelength range observed by GIMI (131-200 nanometers, or
1310-2000
Angstroms), the scientific team estimates that in order to be
observable,
the meteor had to have been at an altitude well above 100
kilometers.
Since its entry velocity was probably in excess of 60 km/sec
(i.e. much
higher than Earth escape velocity of 11.2 km/sec), the energy was
probably available for producing emission in the far-UV at
relatively
high altitudes, due to excitation of the atmosphere and/or
meteoric
constituents.
The most likely emission source, Dr. Carruthers says, is nitric
oxide
(NO) which is produced and excited by dissociation of molecular
nitrogen and its subsequent reaction with atomic oxygen,
producing
emission in the 190-200 nm wavelength range. However, if the
meteor is
of carbonaceous composition, far-UV emissions of carbon monoxide
(CO)
and atomic carbon may be produced as well.
GIMI is one of nine primary experiments on the ARGOS mission,
which
launched into a polar orbit on February 23, 1999 to study space
weather. GIMI's principal objective is to obtain simultaneous
wide-field FUV/EUV images of ionospheric and upper atmospheric
emissions, covering large areas of the earth from a low-earth
orbit.
The GIMI images will be used to determine chemical densities [O+,
nighttime O2, NO and N2] on a global basis and to detect
disturbances
in the ionosphere that are caused by auroral activity, gravity
waves
and foreign materials from meteors, suspected "ice
comets," rocket
exhausts and chemical releases. In between the atmospheric
observations, GIMI is gathering data for an all-sky survey of
stars and
data on celestial diffuse sources at far-ultraviolet wavelengths.
The GIMI instrument has two cameras for simultaneous observations
of
selected targets. Camera 1, which is sensitive in the 75-110 nm
ranges
is primarily being used for observations of the dayside
ionosphere,
auroras, and stellar occultations, and for star field surveys.
Camera 2
is sensitive in the 131-160 and 131-200 nm far-UV wavelength
ranges and
is used for observations of the nightside ionosphere, airglow,
stellar
occultations, star field surveys, and also gas releases and
rocket
plumes at night.
Meteor image and caption,
http://www.pao.nrl.navy.mil/rel-00/images/gimi-flyer.pdf
(99KB)
===============
(2) HOW THE MOON FOUND ITS ORBIT
From Andrew Yee <ayee@nova.astro.utoronto.ca>
From INSCIGHT, 16 February 2000
[http://www.academicpress.com/inscight/02162000/graphb.htm]
16 February 2000, 5 pm PST
How the Moon Found Its Orbit
By Govert Schilling
The most popular theory about how the moon formed -- as a result
of an
apocalyptic collision between Earth and another object -- always
seemed
to have a fatal flaw: It couldn't explain the moon's strange,
tilted
orbit. Now, planetary scientists say that may not be a problem at
all.
On the contrary, new computer simulations show that the tilted
orbit
fits with the impact theory, researchers argue in the 17 February
issue
of Nature.
Most planetary satellites in our solar system orbit within the
equatorial plane of their mother planet. But our moon lies in a
plane
tilted 23 degrees with respect to Earth's equator. Calculations
suggest
that the orbital tilt was smaller shortly after the moon's birth,
some
4.5 billion years ago, but it still must have been at least 10
degrees.
That jars with the widely accepted theory that the moon formed
after
Earth was hit by something the size of Mars. Afterward, the moon
coalesced from impact debris circling Earth in a dense disk.
Previous
studies had shown that this process would give the moon an
orbital tilt
of 1 degree at most.
Using computer models to simulate the interaction of the newly
formed
moon with the remains of the debris disk, William Ward and Robin
Canup
of the Southwestern Research Institute in Boulder, Colorado,
think they
have explained the 10 degree tilt. After the moon had formed at
the
outer edge of the disk, it stirred up waves in the remaining
inner
disk. Within a couple of decades, the researchers say, tidal
interactions between the moon and these waves would push the moon
out
of its nearly equatorial orbit.
So far, two other solutions for the moon's orbital tilt have been
proposed: tidal interactions with the sun, and another major
impact,
either on the moon or Earth. However, both would require several
special conditions to work, says Alan Boss of the Carnegie
Institution
of Washington, D.C. "This new idea is quite nice and fits
naturally in
the giant impact idea," says Boss. "I think there's not
too much of a
problem anymore."
© 2000 The American Association for the Advancement of Science
[Extracted from INSCiGHT, Academic Press.]
==================
(3) NASA BEGINS BUILDING NEXT MISSION TO STUDY COMETS
From NASANews@hq.nasa.gov
Donald Savage
Headquarters, Washington,
DC
February 15, 2000
(Phone: 202/358-1547)
RELEASE: 00-26
NASA BEGINS BUILDING NEXT MISSION TO STUDY COMETS
NASA's Comet Nucleus Tour, or CONTOUR, mission this month took a
giant
step closer to its launch when the project received approval to
begin
building the spacecraft.
Planned for a July 2002 launch, CONTOUR is expected to
encounter Comet
Encke in November 2003 and Comet Schwassmann-Wachmann-3 in June
2006.
The mission has the flexibility to include a flyby of Comet
d'Arrest in
2008 or an as-yet undiscovered comet, perhaps originating from
beyond
the orbit of Pluto. Such an unforeseen cometary visitor to
the inner
solar system, like Comet Hale-Bopp discovered in 1995, would
present a
rare opportunity to conduct a close-up examination of these
mysterious,
ancient objects which normally reside in the cold depths of
interstellar space.
The nucleus of a comet is its heart, believed by scientists to be
a
tiny irregular chunk of ice and rock. To date only one
comet nucleus
has ever been viewed by a spacecraft: Comet Halley in
1986. CONTOUR
will fly past at least two comets and take higher resolution
images
than those of Halley. It will also collect and analyze gas
and dust to
reveal the comet's makeup, greatly improving our knowledge of key
characteristics of comet nuclei and providing an assessment of
their
diversity. CONTOUR also will clear up the many mysteries of
how comets
evolve as they approach the Sun and their ices begin to
evaporate.
The CONTOUR spacecraft will fly by each comet at the peak of its
activity when it's close to the Sun. During each encounter,
the target
comet will also be well situated in the night sky for astronomers
worldwide to make concurrent observations from the ground.
The
spacecraft will fly by each comet at a distance of about 60 miles
(100
kilometers).
After successful completion of both the Preliminary Design Review
and
an independent Confirmation Assessment and the Confirmation
Review at
NASA Headquarters, the comet flyby project is well on its way
toward
completing the spacecraft design. The CONTOUR mission is
managed for
NASA by the Johns Hopkins University Applied Physics Laboratory,
in
Laurel, MD. The Principal Investigator is Dr. Joseph
Veverka of
Cornell University, NY. More information on CONTOUR is available
at:
http://www.contour2002.org
and http://discovery.nasa.gov
================
(4) SIR ARTHUR ENVISIONS WORLDWIDE WARNING SYSTEM
From Space.com, 16 February 2000
http://www.space.com/space/technology/clarke_warn_000215.html
By Leonard David
Senior Space Writer
WASHINGTON -- Space visionary Arthur C. Clarke sees in the 21st
century
a world that is globally networked and geographically transparent
-- one
that blends satellites, telecommunications and information
technologies
to solve global problems.
One such concern that demands early attention, he believes, is
the havoc
created by natural disasters. Each year, countless lives and
billions of
dollars in property are lost to floods, earthquakes, hurricanes
and
volcanic eruptions.
The Clarke Institute for Telecommunications and Information
(CITI) plans
to help tackle these Earth-in-upheaval challenges by pushing a
sort of
early alert system to both plan for and react to such
catastrophes.
Plans for the system, called the Warning and Recovery Network --
or WARN
for short -- were unveiled at a CITI founders' conference, held
February
5 at Intelsat headquarters in Washington, D.C.
Intelsat, a global consortium of some 140-member nations that use
a
network of communications satellites, is the corporate patron of
CITI.
CITI, based in Arlington, Virginia, is dedicated to the writings
and
futuristic thinking of Clarke. It was Clarke who in a 1945
edition of
Wireless World magazine wrote of a system of
"extraterrestrial relays"
located 22,300 miles (35,888 kilometers) above Earth. His idea
gave
birth to the notion of geosynchronous satellites that make much
of
today's telecommunications possible.
Clarke told the CITI audience via a video message that the
group's
intent was to link global talent through the internet.
"Eventually, it may evolve into a worldwide problem-solving
body," he
said.
FULL STORY at
http://www.space.com/space/technology/clarke_warn_000215.html
===========
(5) 400th ANNIVERSARY OF THE BURNING OF GIORDANO BRUNO
From Larry Klaes <lklaes@bbn.com>
Giordano Bruno was a sometimes Dominican monk who really annoyed
the Roman Catholic Church with his differing views on existence
and as a result was burned at the stake on February 17, 1600.
For more details on who Bruno was how all this came about,
see here (contains more links to other Bruno info as well):
http://science.nasa.gov/newhome/headlines/ast21may99_2.htm
========================
(6) SIR FRED RETURNS TO GIVE BIG BANG ANOTHER KICKING
[thank God Fred didn’t live 400 years
ago!]
From The Sunday Telegraph, 13 February 2000
By Robert Matthews
Last week's claim that scientists had re-created a brief moment
of the
Big Bang left me rather puzzled. If they had succeceded, surely I
wouldn't still be around to hear of it? Needless to say, it
wasn't
really true; the scientists had merely re-created some event that
took
place long after the Big Bang itself.
Not that everyone believes that the Big Bang actual happened, of
course. There are any number of cranks out there who insist that
the
idea of the universe emerging from nowhere in a huge explosion
is,
well, cranky.
And then there is Professor Sir Fred Hoyle, Britain greatest
living
astrophysicist, and the Big Bang theory's greatest adversary.
From the behaviour of galaxies to the origin of the chemical
elements,
Hoyle made key discoveries. He would have won the Noble Prize for
physics years ago had his Yorkshireman's frankness not led him to
criticise the Noble Committee for overlooking a young female
astronomer
and awarding the 1974 physics prize to her PhD supervisor.
Reckless troublemaker or not, when Hoyle makes a cosmic
pronouncement,
it is invariably worth hearing. And for the last 50 years, he has
been
insisting that the Big Bang theory is codswallop.
Back in the late Forties, he was one of a triumvirate of
Cambridge
physicists who put forward the Steady State theory, according to
which
the universe never had a beginning, nor will it end. Instead, it
just
stays the same forever, expanding at the same rate, the resulting
drop
in the density of matter being compensated by an equally
steady
creation of matter out of nowhere.
This may seem at least as cranky as the Big Bang theory, but as
Hoyle
liked to point out, the required rate of matter creation is
hardly
shocking; just one extra hydrogen atom appearing in a room-sized
space
every million years or so. Which is certainly rather ess dramatic
than
having an entire universe bursting into existence in one go.
The Steady State model has many attractive features - not the
least of
which is a set of very clear-cut predictions of what the universe
should be like. Yet over the last 40 years a stream of
observational
data has convinced the majority of astronomers that these
predictions
have been falsified. The real universe, they insist, is not
in a steady state.
The evidence is compellingly simple. As long ago as the Fifties,
radio
astronomers announced that galaxies were packed more closely the
together in the distant past - flatly contradicting the Steady
State
theory, but right in line with the Big Bang. Calculations of the
"cooking" of hydrogen in the Big Bang also gave a
near-perfect fit with
the abundance of hydrogen-like elements in deep
space.
But the real clincher came in 1965, when two American engineers
discovered that the whole of space is filled with a very feeble
amount
of heat. For most astronomers, the origin of this heat is clear;
a huge
cosmic explosion billions of years ago - in other words,
the Big Bang.
It would take a knave or a fool to dismiss such evidence. Or an
iconoclast of the stature of Hoyle, who this week launches
his most
comprehensive attack against the Big Bang theory, in a book with
the
archly subversive title *A Different Approach to Cosmology*
(Cambridge
University Press, £35).
Together with two other respected astrophysicists Hoyle
systematically
reviews the evidence for the Big Bang theory, and gives it a
good
kicking. Even if you don’t buy into their claims for the
Steady State
theory (and you'll need to be comfortable with advanced
mathematics
even to make a down-payment), it's hard not to be the impressed
by the
audacity of the demolition job.
The supposedly impressive evidence for galaxies being more
crowded
together in the past, they argue, emerged from woefully
incomplete
surveys of the night sky. Now the surveys are complete, the
results
tally nicely with the Steady State theory.
As for the cooking of hydrogen into other elements, Hoyle and his
colleagues show that ordinary stars are quite capable of doing
this.
And when they do, moreover, they fill the universe with a
feeble amount of heat - just as observed.
I don't expect the vast majority of astronomers to pay the
slightest
attention to Hoyle and his colleagues: frankly, there are too
many
careers riding on the Big Bang being right.
Even so, I can only hope that I possess one-thousandth of Hoyle’s
fighting spirit when I, like him, have reached my 85th year.
Copyright 2000, The Sunday Telegraph
===========
(7) RADAR OBSERVATIONS OF COMETS
J.K. Harmon*),D.B. Campbell, S.J. Ostro, M.C. Nolan: Radar
observations
of comets. PLANETARY AND SPACE SCIENCE, 1999, Vol.47, No.12,
pp.1409-1422
*) ARECIBO OBSERVATORY,HC3 BOX 53995,ARECIBO,PR,00612
CORNELL UNIV,DEPT ASTRON,ITHACA,NY,14853
Seven comets have been detected by Earth-based radars during the
period
1980-1995. All but one of these gave a detectable echo fi om the
nucleus, while three of the comets also showed a broad-band echo
from
large (similar to cm-size) grains in the inner coma. Although all
observations have been of the CW (continuous-wave) type,
which
precludes direct size measurement, the radar cross sections are
consistent with nucleus diameters averaging a few kilometers and
varying over a range of ten. Comparisons with independent size
estimates indicate relatively low radar albedos, implying nucleus
surface densities of 0.5 to 1 g/cm(3), The surfaces of comet
nuclei
appear to be as rough as typical asteroid surfaces, but are
considerably less dense. Analysis of coma echoes indicates that
some comets emit large grains at rates (similar to ton/s) which
are comparable with their gas and dust production rates, There
is also some indirect evidence for grain evaporation or
fragmentation
within a few hundred to a few thousand kilometers of the nucleus.
The
highest priority of future radar observations will be to obtain
delay-Doppler images of a nucleus, which would give direct size
and
shape estimates as well as a more reliable albedo. Delay-Doppler
or
interferometric imaging of the coma echo would also help to
better characterize the grain halo. Ten short-period comets are
potentially detectable during the next two decades, although
the best radar opportunities may well come from comets yet to
be discovered. (C) 1999 Elsevier Science Ltd. All rights
reserved.
===============
(8) METEOROID STREAMS AT MARS
A.A. Christou*) & K. Beurle: Meteoroid streams at Mars:
possibilities
and implications. PLANETARY AND SPACE SCIENCE, 1999, Vol.47,
No.12,
pp.1475-1485
*) UNIVERSITY OF LONDON QUEEN MARY & WESTFIELD COLL,ASTRON
UNIT,SCH MATH SCI,MILE END RD,LONDON E1 4NS,ENGLAND
In order to assess the possibility of meteoroid streams
detectable from
the surface of Mars as meteor showers we have derived minimum
distances
and associated velocities for a large sample of small body orbits
relative to the orbits of Mars and the Earth. The population
ratio for
objects approaching to within 0.2 AU of these two planets is
found to
be approximately 2:1. The smaller relative velocities in the case
of
Mars appears to be the main impediment to the detection of
meteors in
the upper atmosphere of that planet. We identify five bodies,
including
the unusual object (5335) Damocles and periodic comet 1P/Halley,
with
relative orbital parameters most suitable to produce prominent
meteor
showers. We identify specific epochs at which showers related to
these
bodies are expected to occur. An overview of possible detection
methods
taking into account the unique characteristics of the Martian
environment is presented. We pay particular attention on the
effects of
such streams on the dust rings believed to be present around
Mars. (C)
1999 Elsevier Science Ltd. All rights reserved.
=============================
*LETTERS TO THE MODERATOR *
=============================
(9) RESONANT ORBITS AND SMALL NEOS
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
In my recent Space.com article I quote Alan Harris from JPL:
'scientists now realize an asteroid will usually make several
close
passes by the Earth before a collision occurs.' 1999AN10 and the
recent
2000BF19 are good examples. In each case it was predicted that
there
was a chance of an Earth collision IF the asteroid passed through
a
crucial keyhole during the previous orbit. In both cases further
observations confirmed that the object would miss the keyhole.
Alan
pointed out that a keyhole is generally going to be a hundred
kilometres or so across. It would therefore be much easier to
deflect
an object that is headed for a keyhole than one which is heading
directly for the Earth (deflection of 100s of km rather than
1000s).
A further advantage of these types of threatening objects is that
their
close approaches to Earth will make them easier to detect using a
modest (in terms of telescope size), VIGILANT (in terms of sky
coverage) Spaceguard program. We should be able to detect much
smaller
objects than those in *conventional* NEO orbits.
It may therefore turn out that the objects at greatest risk of
collision are the easiest to detect AND the easiest to deflect.
Michael Paine
The Planetary Society Australian Volunteers
====================
(10) DEFENDING EARTH: ONE COMMENT & A QUESTION
From John Richfield <jonr@iafrica.com>
Hi Benny,
I liked Michael Paine's essay. One comment and a question
or so:
> Many asteroids are rich in the raw materials needed for
manufacturing in
> space, and some are easier to reach than the Moon. Of
course, one way to
> deal with an earth-threatening object is to mine it away to
nothing.
Apart from the existence of FeNi objects fallen to earth, what
evidence do we have of riches in raw materials etc? We are
surely
not relying on finding a lot of OsIr are we? :-) I am of course
keen
that the statement be correct, but I'd like to know what role
positive thinking played in the assessment. Secondly,
mining or no
mining, we need at least the same energy to prevent the body from
reaching earth. The mining scenario in this context amounts
to
saying that given sufficient incentive (such as profit) we still
can
deflect the NEO. Right?
On the subject of losing the Saturn blueprints, it might be true
or
not, but the problem that gives me spots before the eyes is that
it
is absolutely plausible. When I think back to the reverent awe
with
which we regarded the space missions in the sixties and seventies
and
how we had dreamed of them in the fifties, the cost of the
samples
and the data returned, then I feel a little sick when I see how
data
and material and expertise were wasted. The very subject of
how to
achieve long-term storage of information in the face of technical
obsolescence is one of our civilisation's greatest
challenges. Is
anyone interested in my writing or collaborating on an essay on
that?
I have considered a few science fiction options for info to
survive
and give our savage descendents a leg up to civilisation again
after
our collapse.
> The idea of blowing up an asteroid makes for good movie
scripts, but is
> not the way to do it in the real universe. Many of the
fragments would
> remain on a collision course and like the blast from a
shotgun; the
> fragments can do up to ten times as much damage as the
original, intact
> object.
Granting the rest of the statement, I am curious about the figure
of
"up to ten times as much damage". Could someone
please elaborate on
the scenario on which it was based? Or was it just intended
to mean
"Possibly lots more damage than leaving the thing
whole"? We had a
thumbsuck confab on the subject of dino killers vs dog killers a
month
or two ago, and no one suggested a seriously disastrous
alternative
then. I'm not arguing, but asking.
> A nuclear bomb is detonated several hundred yards away from
the object.
> Surprisingly, it is the intense radiation generated by the
explosion
> that does the job.
I would have thought that seems a bit far away; is that a
calculation
or a guess and are there options for using tampers or something
to
increase the radiation incident on the NEO?
Cheers,
Jon
================
(11) HOW HARD IS EROS?
From Mayo Greenberg <greenber@strw.leidenuniv.nl>
Dear Benny,
I have not heard any mention of obtaining the mean density of
Eros By
NEAR. This to me seems one of the most important pieces of
information
to be deduced from the orbit of the satellite and the size of
Eros. Ths
provides a basic data point on the composition.
Best regards
Mayo Greenberg
=================
(12) AND FINALLY: STUDY FINDS HEAVY NET USERS ISOLATED
[a timely reminder for some overexerted NEO researchers ...:-)]
New technology strains community bonds, authors argue
From MSNBC, 15 February 2000
http://msnbc.com/news/370692.asp?cp1=1
By David Streitfeld
WASHINGTON POST
PALO ALTO, Calif., Feb. 15 — The Internet is creating
a class of
people who spend more hours at the office, work still more hours
from
home, and are so solitary they can hardly be bothered to call
Mom on her birthday.
THOSE ARE some of the conclusions of a major new study of
Internet
users conducted by Stanford University’s Institute for the
Quantitative Study of Society. But even before its official
unveiling
here today, the survey of 4,113 people was receiving extensive
criticism, guaranteeing another round of debate over the effect
of
this new technology.
“We’re moving from a world in which you know all your
neighbors, see
all your friends, interact with lots of different people every
day,
to a functional world, where interaction takes place at a
distance,”
said Norman Nie, a Stanford professor of political science and
director of the institute. “Can you get a hug, a warm voice,
over the
Internet?”
A quarter of the survey respondents who use the Internet more
than
five hours a week said they spend less time with friends and
family,
either on the phone or in person. Ten percent said it had reduced
out-of-home social activities.
FULL STORY at
http://msnbc.com/news/370692.asp?cp1=1
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