PLEASE NOTE:
*
CCNet 125/2000 - 1 December 2000
--------------------------------
"Hudson is more interested in the positive potential of
these
asteroids than doomsday predictions. 'Scientifically, these are
very
exciting because they are treasure troves of raw materials. As we
work on
the space station and move towards the colonization of space,
they could
provide us with many resources. I like to think of them in a
positive light
because of their potential to us.'"
-- Scott Hudson, Daily Evergreen, 27 November 2000
"The Earth is a much bigger target than the moon. Earth
would have
been bombarded by at least 10 times as many impact events as the
moon,
and these impact cratering processes are immense. The Chixculub
crater that we identified, which is related to the mass
extinction of
dinosaurs and other life 65 million years ago, is puny by
comparison to the
scheme we are talking about. Here we are talking about impacts
that
are 10 times larger, impacts that blasted craters rim-to-rim the
size
of continents on Earth today."
-- David A. Kring, University of Arizona, 30 November 2000
(1) LUNAR METEORITE AGES STRONGLY SUPPORT 'LUNAR CATACLYSM'
Andrew Yee <ayee@nova.astro.utoronto.ca>
(2) LUNAR METEORITES REVEAL LIFE'S TROUBLES
BBC New Online, 30 November 2000
(3) SCOTT HUDSON KEEPS EYE ON ASTEROID TOUTATIS
Exite News, 27 November 2000
(4) LIQUID MIRROR TELESCOPE OBSERVATIONS OF THE 1999 LEONID
METEORS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) EXCHANGE OF LIFE BETWEEN PLANETS
Michael Paine <mpaine@tpgi.com.au>
(6) SHOEMAKER BY LEVY: THE MAN WHO MADE AN IMPACT
Scientific American, December 2000
(7) LEAPING INTO THE FUTURE: ONE HOP AT A TIME
Ron Baalke <baalke@jpl.nasa.gov>
(8) REENTRY SURVIVABILITY
Andrew Yee <ayee@nova.astro.utoronto.ca>
(9) AND FINALLY: EXPLODING WORLD PRODUCTION OF INFORMATION &
GLOBAL
DEMOCRATISATION
Andrew Yee <ayee@nova.astro.utoronto.ca>
=================
(1) LUNAR METEORITE AGES STRONGLY SUPPORT 'LUNAR CATACLYSM'
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News Services
University of Arizona
Tucson, Arizona
Contact Information:
Barbara Cohen (UT), 865-974-6024, bcohen@utk.edu
Timothy D. Swindle (UA), 520-626-5741, tswindle@lpl.arizona.edu
David A. Kring (UA), 520-621-2024, kring@lpl.arizona.edu
Nov 30, 2000
Lunar Meteorite Ages Strongly Support 'Lunar Cataclysm'
By Lori Stiles
Lunar meteorite ages present new, strong evidence for the
"lunar cataclysm,"
a 20-to-200 million-year episode of intense bombardment of the
moon and the
Earth at 3.9 billion years ago -- when the first evidence of life
appeared
on Earth, planetary scientists report in the Dec. 1 issue of
Science.
Whether or not there was life on Earth at the beginning of the
bombardment,
such cataclysmic pounding would have enormous consequences for
life on this
planet, whether by destroying existing life or organic fragments
or by
delivering molecules and creating conditions suitable for life,
the
researchers add.
Barbara Cohen of the University of Tennessee -- Knoxville
analyzed the lunar
meteorite ages for her dissertation research at the University of
Arizona in
Tucson. Timothy D. Swindle and David A. Kring of the UA
collaborated on the
study and are co-authors on the Science article. Swindle
supervised Cohen's
research. Kring is an expert in impact cratering and one of the
discoverers
of the K/T boundary Chicxulub impact site.
Moon rocks returned by the Apollo and Luna missions in the 1970s
suggested
that Earth's moon was blasted in a maelstrom of solar system
debris at 3.9
billion years ago. A great swarm of asteroids or comets pounded
the lunar
surface during a brief pulse in geologic time, melting rocks,
excavating
vast craters and resurfacing Earth's natural satellite.
But for safety and communications reasons, both manned and
robotic
spacecraft were landed near the moon's equator, on the side
facing Earth. No
one could say if just this part of the moon or the entire moon
had been
hammered.
Cohen, Swindle and Kring bring the most significant data in
nearly 30 years
to bear on this question. They used an argon-argon dating
technique in
analyzing impact melt ages of four lunar meteorites -- rocks
ejected at
random from the moon's surface and that landed on Earth after a
million or
so years in space. They find from the ages of the
"clasts," or melted rock
fragments,
in the breccia meteorites that all of the moon was bombarded 3.9
billion
years ago, a true global lunar cataclysm.
Further, although the moon may have been bombarded before 3.9
billion years
ago, the scientists find no evidence for it. If there were no
earlier
bombardment, scientists must jettison theoretical models that
assume a
steady falloff in the lunar and inner solar system cratering rate
through
time.
"Given the model of what was going on in the solar system,
there is no
obvious reason why you should suddenly have a bunch of things
banging on the
moon 4 billion years ago and not 4.2 billion years ago,"
Swindle said.
But the most dramatic implication is what happened during this
event on
Earth.
"The Earth is a much bigger target than the moon, "
said Kring, associate
professor at the UA Lunar and Planetary Lab. "Earth would
have been
bombarded by at least 10 times as many impact events as the moon,
and these
impact cratering processes are immense. The Chixculub crater that
we identified, which is related to the mass extinction of
dinosaurs and
other life 65 million years ago, is puny by comparison to the
scheme we are
talking about. Here we are talking about impacts that are 10
times larger,
impacts that blasted craters rim-to-rim the size of continents on
Earth
today."
"The bombardment would have charged the atmosphere with
silicate vapor and
vaporized the oceans, so if there was life on Earth before the
bombardment,
the question is what, if anything, survived," Swindle said.
Perhaps some
genetically primitive "extremeophiles" survived, he
added. This kind of life
is found on Earth today deep in rocks or living at the ocean
vents.
What did the bombarding? More likely asteroids than comets, based
on some
evidence from meteoritic trace constituents involved in the
impacts and on
other studies on what was happening at the time in the asteroid
belt, Kring
suggests.
"When we first started this research, the goal was to find
something older
than 3.9 billion years," Cohen said. "We were very
surprised at the evidence
presented by seven different impacts, which pointed to 3.9
billion years."
Swindle said, "Going into this study, I would have bet that
we wouldn't have
found these results. I would have bet that we would have seen
impacts
earlier than 3.9 billion years ago."
Kring said, "I've quit being surprised at what impact
cratering processes
can do."
Kring, director of the Lunar and Planetary Lab's Space Imagery
Center, has
just added new web pages on impact cratering, the lunar cataclysm
and origin
of life, the moon and lunar meteorites at the Space Imagery
Center web
sites.
(Bill Dockery, UT News Services, 865-974-2225, dockerb@utk.edu, is also a
media contact on this story.)
Related Links
* http://www.lpl.arizona.edu/SIC/impact_cratering/intro/
* http://www.lpl.arizona.edu/SIC/impact_cratering/lunar_cataclysm/
* http://www.lpl.arizona.edu/SIC/impact_cratering/origin_of_life
* http://www.lpl.arizona.edu/SIC/moon/
* http://www.lpl.arizona.edu/SIC/moon/lunar_meteorites/
IMAGE CAPTIONS:
[ http://uanews.opi.arizona.edu/cgi-bin/WebObjects/UANews.woa/wa/SRStoryDetails?ArticleID=2732
]
[Image 1]
The moon's crater, Tycho, taken with NASA's Lunar Orbiter 5
spacecraft
medium-resolution camera (1966-67).
[Image 2]
Barbara Cohen holds chips of meteorites DaG262 and DaG400 used in
the
analysis.
[Image 3]
David A. Kring.
[Image 4]
Timothy D. Swindle.
================
(2) LUNAR METEORITES REVEAL LIFE'S TROUBLES
From the BBC New Online, 30 November 2000
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1048000/1048280.stm
By BBC News Online science editor Dr David Whitehouse
A new study of Moon meteorites provides fresh evidence that the
Earth and
its satellite underwent an intense period of cosmic bombardment
just under
four billion years ago.
An analysis of four of the 20 or so known lunar meteorites
suggests that the
Moon's surface was melted by a torrent of impacts.
It is estimated that this lunar catastrophe would have lasted
only about
200,000 years but, in that time, nearly 2,000 large craters would
have been
formed as well as many of the Moon's giant impact basins.
Scientists say that the Earth would have been bombarded to a far
greater
extent and that the frequent impacts could have delayed the
emergence of
life on the primitive world.
FULL STORY at
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1048000/1048280.stm
==================
(3) SCOTT HUDSON KEEPS EYE ON ASTEROID TOUTATIS
From Exite News, 27 November 2000
http://news.excite.com/news/uw/001127/university-education-27
Washington State U. prof keeps eye on asteroid
By Jake Smulkowski
Daily Evergreen
Washington State U.
(U-WIRE) PULLMAN, Wash. -- Washington State University associate
professor
Scott Hudson is helping to keep the world informed about
potentially
hazardous asteroids.
Hudson, an astronomer with the School of Electrical Engineering
and Computer
Science, has been monitoring the asteroid Toutatis in its path
around the
sun.
Toutatis, one of the largest potentially hazardous asteroids at
about five
miles across, comes into relatively close quarters with Earth
every four
years.
Hudson studies the asteroid with NASA's Goldstone planetary radar
in
California and another facility in Puerto Rico. Hudson said the
radar
systems are fairly simple.
"It's a lot like the radar at an airport that tracks
airplanes," he said.
"It bounces signals off of the object, and we analyze the
readings. We can
predict orbits very accurately, and we can predict them for
hundreds of
years in the future."
The people of Earth should not prepare for Armageddon just yet,
though.
Next time the asteroid passes near Earth, in late November of
2004, it still
will be twice the distance from Earth as the moon.
"This is one of the largest of the Earth-crossing asteroids
(asteroids that
cross the Earth's orbit), and it's the one that comes closest to
the Earth's
orbit," Hudson said. "Still, we are not worried about
this asteroid. We
study a large number of potentially hazardous asteroids. In fact,
we study
hundreds of objects."
The asteroid will come close enough that it might be visible by
the naked
eye in very dark sky areas, Hudson said.
Toutatis is an unusual asteroid - its orbit is nearly circular.
"Most (asteroids) have fairly elliptical orbits,"
Hudson said. "They are
often pulled off from the main asteroid belt past Mars by the
gravitational
pulls of the planets, especially Jupiter.
"I've been working on radar astronomy for about 15 years. I
am mainly
interested in the asteroids that cross the Earth's orbit."
Hudson said the public is interested in Earth-crossing asteroids
because of
disaster scenarios.
Perhaps rightly so.
"The amount of energy released in an impact is roughly
equivalent to 100,000
megatons of TNT per kilometer of asteroid diameter," he
said.
The nuclear bomb dropped at Hiroshima released the equivalent of
one-fiftieth of a megaton.
Hudson is more interested in the positive potential of these
asteroids than
doomsday predictions.
"Scientifically, these are very exciting because they are
treasure troves of
raw materials," Hudson said. "As we work on the space
station and move
towards the colonization of space, they could provide us with
many
resources.
"I like to think of them in a positive light because of
their potential to
us."
(C) 2000 Daily Evergreen via U-WIRE
=============
(4) LIQUID MIRROR TELESCOPE OBSERVATIONS OF THE 1999 LEONID
METEORS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[From October 2000 issue of ORBITAL DEBRIS QUARTERLY NEWS, NASA
JSC,
http://www.orbitaldebris.jsc.nasa.gov/newsletter/v5i4/v5i4.html#news5]
Liquid Mirror Telescope Observations of the 1999 Leonid Meteors
By J. Pawlowski
The November 1999 Leonid Meteor Shower was observed and
videotaped using a
Liquid Mirror Telescope (LMT) located at the Johnson Space Center
(JSC)
Observatory near Cloudcroft New Mexico. This is the largest
aperture optical
instrument ever used for meteor studies. The sensitivity of the
LMT along
with its automated meteor detection software enabled detection of
Leonid
meteors in the 5 to 12 magnitude range. Leonids of such faint
magnitudes
were unable to be seen using our low light level video camera
which was
operating concurrently at the same location. Our purpose was to
use the data
from both sources to validate the Leonid Mass Distribution Model
derived at
JSC by Dr. Mark Matney. This model along with other meteor and
orbital
debris models is used for meteoroid and orbital debris risk
assessment
performed prior to every Space Shuttle Mission.
A total of 151 Leonids were detected by the LMT over three nights
of
observations (November 17, 18, & 19). Their masses were
estimated to be
between 10**-4 and 10**-8 grams using meteor analysis software
also
developed at JSC. A mass distribution of these lightweight
Leonids was
calculated, and the slope of their mass distribution was compared
to the
slope of mass distribution of the Leonid Meteor Mass Distribution
Model.
There was excellent agreement over the 0.002 to 0.02 milligram
range. This
agreement along with the agreement in the 0.02 to 0.2 gram range
based on
data from our low light level cameras reported in the April issue
of this
publication supports our continued use of the model.
==============
(5) EXCHANGE OF LIFE BETWEEN PLANETS
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
Further to comments from Paul Davies and I about "lifeboats
in space", the
idea is also raised in a recent paper published in Planetary and
Space
Science. The PDF can be downloaded from
http://www.elsevier.com/inca/publications/store/2/0/0/
(until 1 Dec 2000)
Details and a relevant extract are below.
regards
Michael Paine
Planetary and Space Science
Volume 48, Issue 11, 01-September-2000
Curt Mileikowsky, Francis A. Cucinotta, John W. Wilson, Brett
Gladman, Gerda
Horneck, Lennart Lindegren, Jay Melosh, Hans Rickman, Mauri
Valtonen, J.Q.
Zheng,
Risks threatening viable transfer of microbes between bodies in
our solar
system,
Planetary And Space Science (48)11 (2000) pp. 1107-1115
With relatively long viable flight times in space of about
100,000 years,
the following conclusions can also be drawn:
* Even if life originated only once, either on Earth or on Mars,
it
would still have had a very high probability of avoiding
catastrophic
extinction by the largest impactors during the heavy bombardment
period
by orbiting around its planet (or the Sun) inside ejecta and
returning to
its planet tens of thousands of years later once conditions there
had again
become habitable. (This life-saving orbiting could be caused by
the same
impact that caused the extinction or by earlier impacts.)
* And if longer times of absence from a planet were necessary for
survival, then desendants of microbes that had originated on say
Earth, been transported to Mars and proliferated there, could be
moved back to Earth again and again for periods of up to tens or
hundreds
of millions of years, thus preserving the original life.
* In the biological evolutionary literature a lot is written
about
extinctions that were possibly caused by impacts.They are always
presented
as partial extinctions, for special groups of species, special
environments, etc., never of course as complete extinction of all
life on
Earth... with one exception: a very early collision with a
Mars-sized
planet, assumed to have created the Moon, would certainly have
extinguished all life on Earth had any been there.
* The early, very few giant impacts on Earth and Mars which
caused
large-scale boiling off of oceans might have extinguished either
most
life on the planet except microbes dwelling in rock deep under
the surface,
near the temperature wall, or all of life. The first of these
two alternatives may seem more probable, but the second cannot be
excluded.
* If all early life was extinguished by impact on the Earth or
Mars,
it is very improbable that it happened at the same time on both
of them.
If it happened on one of them, life could probably have returned
from
the other via ejecta carrying viable microbes.
One consequence of this: hypotheses as to whether the origin of
life was
relatively easy and frequent or not need not be in influenced by
the idea of
early life being often extinguished.
===============
(6) SHOEMAKER BY LEVY: THE MAN WHO MADE AN IMPACT
From Scientific American, December 2000
http://www.sciam.com/2000/1200issue/1200reviews2.html
THE EDITORS RECOMMEND
David H. Levy's Shoemaker by Levy: The Man Who Made an Impact
Princeton University Press, Princeton, N.J., 2000 ($24.95).
Their names are memorably linked to Comet Shoemaker-Levy 9, which
they
discovered in 1993 and which captured worldwide attention when 21
fragments
of it crashed into Jupiter in July of 1994. Eugene M. Shoemaker,
who died in
an automobile accident in 1997, was a geologist who spent much of
his career
studying impact craters on the moon and Earth. (He
"practically invented the
field of astrogeology," according to Paul W. Chodas of the
Jet Propulsion
Laboratory.) Levy is a writer on astronomy and the discoverer of
21 comets.
He skillfully describes Shoemaker's work and sharply delineates
his strong
personality. Shoemaker got his lifelong wish to see an impact
when that
comet struck Jupiter. And his wish to go to the moon, thwarted by
his
health, was fulfilled when the spacecraft Lunar Prospector,
carrying one
ounce of his ashes, crashed onto the lunar surface five years to
the week
after the last traces of Comet Shoemaker-Levy 9 disappeared.
==============
(7) LEAPING INTO THE FUTURE: ONE HOP AT A TIME
From Ron Baalke <baalke@jpl.nasa.gov>
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Carolina Martinez (818) 354-9382
FOR IMMEDIATE
RELEASE
November 28, 2000
LEAPING INTO THE FUTURE: ONE HOP AT A TIME
A small hopping robot with froglike abilities that moves by a
combination of
rolls and hops to its desired destination may someday hop a ride
to an
asteroid and leap its way to other planets in the search for
water.
The frogbot, featured as the "robot of the month" in
the Robot Watch news
section of Discover magazine's December issue, weighs in at 1.3
kilograms (3
pounds) and is powered by a single motor. It is equipped with a
camera,
solar panels, sensors and onboard computer that executes commands
autonomously, making the robot ideally suitable for exploration
of distant
planets, comets and asteroids.
Under development jointly by NASA's Jet Propulsion Laboratory and
the
California Institute of Technology, both in Pasadena, Calif., the
frogbot
can steer and right itself.
"Hopping is a more efficient form of transportation in
low-gravity
environments," said Dr. Paolo Fiorini, an engineer in the
robotics group at
JPL. "Our hopping robot performs much like a frog, except
that it only has
one leg and no tongue. It has a spring between its knees that
makes it bend
its legs and hop. When the spring releases, the frogbot takes a
1.8-meter
(6-foot) hop on Earth, which could become a 6- meter (20-foot)
leap under
low-gravity conditions on planets like Mars, depending on
terrain."
Engineers believe that in low-gravity environments, such as small
planets,
and in micro-gravity environments, such as asteroids, wheels
successfully
used on rovers may not be the most efficient form of locomotion.
In
laboratory experiments, slithering, rolling and hopping have been
shown to
be alternative methods of propulsion.
In the future, NASA envisions missions involving dozens of small
robotic
vehicles. "To be effective, a small exploratory robot
vehicle must
frequently go over obstacles that are many times its body
size," said Joel
Burdick, the Caltech co-inventor of the robot. "Hopping or
leaping motions
are some of the few effective ways for small vehicles to overcome
such
relatively large obstacles."
"Our goal was to come up with a locomotion method and design
that would use
a minimal number of instruments and that would be small, compact,
lightweight and still be able to perform useful scientific
study," said Dr.
Neville Marzwell, head of the Advanced Projects Office at JPL.
Researchers
at Sandia National Laboratories in Albuquerque, N.M., have also
developed a
hopping device, with more limited maneuverability.
The frogbot has shown better mobility than rovers on certain
terrain. It can
be developed to reach canyon walls and other remote areas, be
manufactured
at a lower cost and multiple numbers of the device can be
released onto a
planet's surface to cover large distances and communicate with
each other.
One frogbot could be lost without hindering the whole network.
The hopping robot technology will be ready in about three to five
years and
could help scientists capture images and collect ground samples.
One of the
major challenges facing engineers is precision navigation
necessary to
control the hopping robot. Engineers are also developing a
hopper that adheres and climbs vertical walls and are testing
prototypes on
different ground terrains.
Pictures are available at
http://technology.jpl.nasa.gov/gallery/robotics/robot_index.html
The Advanced Projects Office of Space Flight at NASA Headquarters
is the
primary source of funds for this work, which was also sponsored
by a
National Science Foundation grant through the Center for
Neuromorphic
Systems Engineering at Caltech. Managed for NASA by Caltech, JPL
is the lead
U.S. center for robotic exploration of the solar system.
=============
(8) REENTRY SURVIVABILITY
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[From October 2000 issue of ORBITAL DEBRIS QUARTERLY NEWS, NASA
JSC,
http://www.orbitaldebris.jsc.nasa.gov/newsletter/v5i4/v5i4.html#news3]
Reentry Survivability Analysis of Extreme Ultraviolet Explorer
(EUVE)
By R. O'Hara
A reentry analysis of the Extreme Ultraviolet Explorer (EUVE)
spacecraft was
performed using the Object Reentry Survival Analysis Tool (ORSAT)
- Version
5.0. The analysis was done in response to a request by NASA
Headquarters and
Goddard Space Flight Center (GSFC) after a preliminary assessment
had shown
that the EUVE reentry may produce a debris area greater than the
limit set
within the NASA Safety Standard 1740.14 guidelines.
NASA's 3243 kilogram EUVE spacecraft was launched on June 7, 1992
from Cape
Canaveral Air Station on board a Delta II launch vehicle into a
528
kilometer, 28.5 degree inclined orbit. With the spacecraft
nearing its end
of mission and a possible reentry into the Earth's atmosphere
expected as
early as October 2001, personnel at Goddard Space Flight Center
performed a
reentry analysis using the NASA Johnson Space Center Debris
Assessment
Software (DAS) - Version 1.0, in accordance with NASA Policy
Directive
8710.3. In the GSFC analysis, there were 18 individual objects
predicted to
survive. The total casualty area calculated for these surviving
objects was
12.41 m**2, which exceeds the 8 m**2 limit set in the NASA safety
standard.
The large debris area implies a potential human casualty risk of
approximately 1 in 5,300. The EUVE spacecraft was not designed
with a
propulsion system and therefore cannot perform a controlled
reentry. In
order to mitigate the potential risk to human safety from an
uncontrolled
reentry of the EUVE spacecraft, a retrieval of the spacecraft
using the
Space Shuttle was considered. However, since DAS is a lower
fidelity model
and tends to produce a more conservative result, the Orbital
Debris Program
Office at JSC was asked to perform a more detailed reentry study
using the
higher fidelity NASA-Lockheed Martin ORSAT model to determine if
taking such
a measure would be necessary.
Several sophisticated material and thermal properties are
included in ORSAT
but do not exist in the DAS code. These enhancements tend to
result in fewer
objects surviving reentry when using ORSAT as opposed to DAS for
a reentry
analysis. For example, the emissivity is set to 1.0 for all
materials
available in DAS, implying blackbody radiation for each component
analyzed.
Thus, objects in DAS tend to lose heat faster and are more likely
to
survive. In ORSAT, however, the emissivity can be adjusted based
upon what
type of material the object is composed of. ORSAT also considers
heat of
oxidation during reentry, which means that the object gains heat
faster and
will demise more readily. Heat of oxidation is not considered in
DAS. ORSAT
also allows for thermal conductivity. With this enhancement and
using a
layered approach to modeling the fragments, ORSAT can reduce the
overall
debris area by allowing for objects to partially ablate. In
contrast to this
method, DAS will allow the entire fragment to survive. And
finally, ORSAT
enables the user to supply a wall thickness for an object, making
it easier
to model hollow objects. DAS treats all objects as solid and
therefore
requires a workaround to approximate the reentry heating to a
hollow object.
This workaround has been validated using comparisons with ORSAT
runs, though
the more direct approach used by ORSAT is more reliable.
In the ORSAT analysis, only the objects shown to survive with the
DAS model
were evaluated, and the high fidelity features of ORSAT were
applied to the
reentry analysis. Reentry of the EUVE spacecraft was considered
to occur at
an altitude of 122 kilometers with breakup occurring at 78
kilometers. All
of the objects were considered exposed to reentry heating at this
breakup
altitude. Objects were also analyzed for possible shielding
affects by other
components. Any object shown to demise at the breakup altitude,
but was
considered shielded by other spacecraft components, was
reanalyzed starting
at the demise altitude for the object shielding it. This allowed
for some
conservatism since in reality these objects would have
experienced some
heating and possible ablation prior to the demise of the object
shielding
it. The final debris area calculated from the more sophisticated
ORSAT
analysis of the surviving fragments came to a total of
approximately 5.95
m**2, which is well under the 8 m**2 NASA constraint.
The more detailed reentry study of the EUVE spacecraft done using
ORSAT has
shown the future uncontrolled reentry of EUVE to be of an
acceptably low
risk to human safety and therefore mitigation measures are
unnecessary.
=============
(9) AND FINALLY: EXPLODING WORLD PRODUCTION OF INFORMATION &
GLOBAL
DEMOCRATISATION
From Andrew Yee <ayee@nova.astro.utoronto.ca>
University of California-Berkeley
Contact:
Kathleen Maclay, Media Relations
(510) 643-5651
18 Oct 2000
UC Berkeley professors measure exploding world production of new
information
Berkeley -- Two University of California, Berkeley, professors
have just
finished analyzing all new data produced worldwide last year --
on the
Internet, in scholarly journals, even in junk mail -- and report
not just
staggering totals, but a "revolution" in information
production and
accessibility.
In their report, "How Much Information?" professors Hal
Varian and Peter
Lyman of the UC Berkeley School of Information Management &
Systems (SIMS)
report new information production in terms of paper, film,
optical and
magnetic data. They analyzed industry and government reports for
production
of information that also includes e-mail, digital production,
videos, DVDs,
CDs, broadcast outlets, photographs, books and newspapers.
The study has, for the first time, used "terabytes" as
a common standard of
measurement to compare the size of information in all media,
linking and
interpreting research reports from industry and academia. One
terabyte
equals a million megabytes or the text content of a million
books. This
standard makes it possible to compare growth trends for different
media
using one universal standard.
The numbers in the UC Berkeley report are mindboggling
* The directly accessible "surface" Web consists of
about 2.5 billion
documents and is growing at a rate of 7.3 million pages per day.
* Counting the "surface" Web with the "deep"
Web of connected
databases, intranet sites and dynamic pages, there are about 550
billion
documents, and 95 percent is publicly accessible.
* Fifty percent of all Internet users are native English
speakers,
while English language Web sites account for about 78 percent of
all
Web sites, and 96 percent of E-commerce Web sites.
* A white-collar worker receives about 40 e-mail messages daily
at the
office.
* Ninety percent of the world's e-mailboxes were found in the
United
States in 1984, but that dropped to 59 percent by the end of
1999.
E-mail production accounts for about 500 times as much
information as
Web page production each year.
* Worldwide production of books increased by 2 percent in the
last
year.
* Production of newspapers in the last year decreased by 2
percent.
* The United States produces 35 percent of all print material, 40
percent of the images and more than half of the digitally stored
material.
SIMS professors Lyman and Varian and their research assistants
James Dunn,
Aleksey Strygin and Kirsten Swearingen translated original
content volume
into bytes, using the terabyte as the project's smallest
practical measure.
Then they calculated how much storage each type of media takes
when
subjected to different compression techniques, and factored in
anticipated
duplication.
The professors said they were struck by three emerging trends.
One is "the 'democratization of data," the vast amount
of unique information
stored and also created by individuals. Original documents
created by office
workers represent nearly 90 percent of all original paper
documents, while
56 percent of magnetic storage is in single-user desktop
computers.
"A century ago, the average person could only create and
access a small
amount of information," wrote Varian and Lyman in their
report. "Now,
ordinary people not only have access to huge amounts of data, but
are also
able to create gigabytes of data themselves and, potentially,
publish it to
the world via the Internet."
The second surprise for the professors was the finding that print
accounts
for such a miniscule amount of the total information storage. But
they said
it doesn't mean print is dead, rather it is a very efficient and
concentrated form for the communication of information.
The third striking finding for them was the dominance of digital
information
and its phenomenal growth. This further feeds the democratization
of data,
they said, because digital information is potentially accessible
anywhere on
the Internet and is a "universal" medium because it can
copy from any other
format.
But just because storing vast amounts of information no longer
requires an
investment in real estate, the researchers said the ease of
production and
access to information may lead people to turn over personal data
management
to specialized businesses with giant data storage systems.
"After all," they wrote, "would you rather keep
all your family photos on
your PC hard drive, and risk losing everything if it crashes, or
on a secure
site managed by Kodak? On the other hand, individuals may prefer
to keep
information about themselves in smaller systems that only they
control."
The researchers also forecast that businesses will be
tremendously affected
by this increase in individuals' instant access to real-time
company data,
something that a few years ago was restricted to the upper
management.
"The difficulty will be in managing this information
effectively making sure
that your suppliers, your employees, and your customers not only
have access
to the data they need to make informed decisions, but also can
locate,
manipulate and understand it," the report said.
Lyman and Varian caution that our ability to store and
communicate
information has far outpaced the ability to search, retrieve and
present it.
That's one reason for a place like SIMS, where people can learn
the
techniques and technologies for sorting the valuable information
from the
superfluous, they said.
"Information management -- at the individual,
organizational, and even
societal level -- may turn out to be one of the key challenges we
face," the
report said.
"It's the next stage of literacy," Lyman said.
The latest report is not in printed form, because its authors see
it as a
"living" document. It can be found at
http://www.sims.berkeley.edu/how-much-info/index.html
and will be updated
periodically in response to comments from readers.
"It's a good way to kick off a discussion of what
information is. We don't
have a very good way of talking about information because it's
changing so
fast," said Varian, also co-author of "Information
Rules A Strategic Guide
to the Network Economy" (Harvard Business School Press,
1998).
"In the past, we've talked about information in terms of the
size of a
physical inventory, such as counting books or films," Lyman
said. "But in
the future, the size and format of information will be
dynamically reshaped
to the needs of the reader."
EMC Corp., the world's largest data storage systems company,
financed the
research.
###
NOTE: Hal Varian is available at (510) 642-9980 and Peter Lyman
at (510)
642-1087.
Links:
* "How Much Information?" report
http://www.sims.berkeley.edu/how-much-info/index.html
* EMC Corp.
http://www.emc.com/
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CCNet ESSAY, 1 December 2000
----------------------------
"In this essay I suggest that, whereas (1) there can be
little doubt
that life abounds throughout the universe and is not confined to
Earth, and (2) under special circumstances interplanetary
transport of
microbes in impact ejecta may be possible, in view of the
evidence to
date the panspermia hypothesis constitutes a philosophical notion
rather
than a scientific theory."
-- Andrew Glikson, 30 November 2000
TERRESTRIAL VS. EXTRATERRESTRIAL
BIOGENESIS: WHEN THE TOTAL IS GREATER THAN
THE SUM OF THE PARTS
By Andrew Glikson <geospectral@spirit.com.au>
Australian National University.
Canberra, ACT 0200
Suggestions of cometary origin and/or transport of microbes and
of universal
seeding of life from cometary dust, colloquially known as
panspermia (eg.
Hoyle and Wichramasinghe, 1980), constitute an extraordinary
claim.
According to Carl Sagan, "Extraordinary claims require
extraordinary
evidence". In this essay I suggest that, whereas (1) there
can be little
doubt that life abounds throughout the universe and is not
confined to
Earth, and (2) under special circumstances interplanetary
transport of
microbes in impact ejecta may be possible, in view of the
evidence to date
the panspermia hypothesis constitutes a philosophical notion
rather than a
scientific theory.
[continued]