PLEASE NOTE:
*
CCNet 5/2001 - 11 January 2001
------------------------------
Correction: In the usual hurry compiling and posting the CCNet, I
mixed up
Max *Wallis* with Bruce *Willis* in today's CCNet
Special. Sorry about that,
Max & Bruce. I hope readers will forgive me too for all the
other spelling
mistakes that invariably occur time and again. BJP
-----------------------
(1) NEAR SHOEMAKER PRIMED FOR FINAL WEEKS IN ORBIT
Ron Baalke <baalke@jpl.nasa.gov>
(2) ASTEROID PROBE MAY BITE THE DUST
The Guadian, 11 January 2001
(3) CALL FOR OBSERVATIONS: THE JANUARY COMA BERENICIDS
Alastair McBeath <mcbal.gwyvre@virgin.net>
(4) NASA SEEKS CRATER RATERS
BBC News Online, 9 January, 2001
(5) NEO-EXPERT & CCNet MEMBER, GENERAL PETE WORDEN THE NEXT
NASA
ADMINISTRATOR? GOOD LUCK, PETE!
NASA Watch, 8 January 2001
(6) ELEVEN NEW MOONS FOR JUPITER
Ron Baalke <baalke@zagami.jpl.nasa.gov>
(7) IMPACTS AND EARTH EVOLUTION
Margaret Penston <mjp@ast.cam.ac.uk>
(8) ENVIRONMENTAL EFFECTS OF IMPACTS
Michael Paine <mpaine@tpgi.com.au>
(9) ARCHAEO-ASTRONOMERS MAY HAVE BEEN FOOLED BY 20th-CENTURY
STONEHENGE
DESIGN
The Independent, 9 January 2001
(10) THE ETHICAL DIMENSIONS OF SPACE SETTLEMENT
M. J. Fogg
(11) AND FINALLY: MOON HOAX SPURS CRUSADE AGAINST BAD ASTRONOMY
The New York Times, 11 January 2001
====================
(1) NEAR SHOEMAKER PRIMED FOR FINAL WEEKS IN ORBIT
From Ron Baalke <baalke@jpl.nasa.gov>
http://www.jhuapl.edu/public/pr/010110.htm
10 January 2001
NEAR Shoemaker Primed for Final Weeks in Orbit
Low Flyovers Lead to Feb. 12 Controlled Descent
The NEAR Shoemaker spacecraft - the first to orbit an asteroid -
embarks on
a series of low-altitude passes over 433 Eros this month in a
prelude to its
daring February descent to the surface of the rotating,
21-mile-long space
rock.
The orbit segment of NASA's Near Earth Asteroid Rendezvous (NEAR)
mission
wraps up Feb. 12 with NEAR Shoemaker's controlled descent to
Eros, a tricky
maneuver that will allow the craft's digital camera to snap
close-ups of the
asteroid's cratered, boulder-strewn landscape. But the weeks
before the
historic event won't be much easier, as NEAR mission operators
and
navigators take the spacecraft on several low passes over the
ends of the
potato-shaped Eros from Jan. 24-28.
"NEAR Shoemaker is nearly out of fuel, and by the end of
January it will
have completed its scientific objectives at Eros," says Dr.
Robert W.
Farquhar, NEAR Mission Director at The Johns Hopkins University
Applied
Physics Laboratory in Laurel, Md. "The maneuvers are kind of
risky, but we
want to end the mission getting a lot of bonus science - with
images better
than we've ever taken."
On Jan. 24, NEAR Shoemaker will dip from its current 22-mile
(35-kilometer)
circular orbit to begin a four-day series of flyovers. The
spacecraft will
complete five to six passes, each within about 3 to 4 miles (5 to
6
kilometers) of the surface. In the early hours of Jan. 28 the
spacecraft
will zip between 1 to 2 miles (2 to 3 kilometers) over the
surface - closer
than it has ever come before.
"The flyovers will give us a detailed look at the surface,
much like we saw
when the spacecraft came within 3 miles of Eros during the first
low flyover
in October," says NEAR Project Scientist Dr. Andrew F.
Cheng, of the Applied
Physics Laboratory. "This time we're going over different
areas, so we can
find out if the small-scale geological features we saw in the
earlier images
are typical of the surface."
The spacecraft will swing out from that low pass back to a
22-mile orbit,
where it will stay until the controlled descent. Mission
designers are
working out the final details of the descent, but they plan to
slow the
craft's fall with several intermittent engine burns.
NEAR Shoemaker's telescopic camera will gather high-resolution
images during
the last 3 miles of the maneuver, until about 1,650 feet (500
meters) above
the asteroid. Before touching down near Eros' distinctive
"saddle"
depression, NEAR Shoemaker could deliver images showing features
as small as
4 inches (10 centimeters) across.
"NEAR Shoemaker was never designed to land, so that's not
the main goal of
the controlled descent," Farquhar says. "The definition
of success here is
getting the close-up images. We're not optimizing this maneuver
to ensure
the spacecraft survives this event."
The first launch in NASA's Discovery Program of low-cost
planetary missions,
NEAR Shoemaker has been in orbit around Eros since Feb. 14, 2000,
conducting
the first in-depth study of an asteroid. The Applied Physics
Laboratory
designed and built the spacecraft and manages the NEAR mission
for NASA. The
NEAR team also includes NASA's Jet Propulsion Laboratory; Cornell
University; Massachusetts Institute of Technology; University of
Maryland;
University of Arizona; NASA's Goddard Space Flight Center;
Southwest
Research Institute; Northwestern University; Space Environment
Center; Solar
Data Analysis Center; Malin Space Science Systems, Inc.;
University of
California, Los Angeles; Catholic University; Max Planck
Institute for
Chemistry; and Computer Sciences Corp.
For the latest news and images visit the NEAR Web site at
(near.jhuapl.edu).
__________________
Media contact:
JHU Applied Physics Laboratory:
Michael
Buckley
Helen Worth
Laurel, MD
20723
Laurel, MD 20723
Phone: 240-228-7536
Phone: 240-228-5113
E-mail:
E-mail:
michael.buckley@jhuapl.edu
helen.worth@jhuapl.edu
===============
(2) ASTEROID PROBE MAY BITE THE DUST
From The Guadian, 11 January 2001
http://www.guardianunlimited.co.uk/international/story/0,3604,420566,00.html
Tim Radford, science editor
After a year of long distance courtship, a spacecraft and its
target could
be about to come to a touching end. A near-Earth asteroid
rendezvous probe
called Shoemaker could be about to land on the surface of a giant
asteroid
called Eros - and then die.
Eros is a peanut-shaped lump of rock the size of Manhattan, 21
miles long
and eight miles wide and eight miles thick, now tumbling through
space 150m
miles away, beyond the orbit of Mars.
The $224m (£150m) probe, named for the late Gene Shoemaker, who
trained the
Apollo astronauts to recognise rocks on the moon, was launched in
1996 to
catch up with Eros and take a closer look.
It kept its date in deep space on February 14 last year, and
began a stately
waltz around its partner, taking ever closer looks at the pitted
surface of
the lump of rock in orbit around the sun.
Asteroids are thought to be the building blocks of a planet that
should have
formed somewhere between Mars and Jupiter, but never came
together. But a
number have become dislodged, and are now seen as potential
cosmic traffic
accidents.
Shoemaker was the first robot probe to take a long close look at
a possible
future problem. While Eros tumbled head over heels every five
hours,
Shoemaker has been swooping to within three miles of the surface
to
photograph its pockmarked face.
But the courtship could soon be over. Its mission controllers are
contemplating a "controlled descent" on to the surface
on February 12.
"We are out of time, out of money and out of fuel,"
said Robert Farquhar, of
Johns Hopkins University's applied physics laboratory in
Baltimore, which
built the spacecraft. "This is the first time anyone has
tried to land
anything on a small body. It would be a nice way to end it."
The spacecraft weighs 1,775lb. It will be travelling three feet a
second
when it hits Eros. "That's jogging speed, but if you hit a
brick wall when
you're jogging, it hurts," he said. "It's risky, but we
will get a lot of
bonus science."
Duncan Steel, an asteroid expert at the University of Salford,
suggested
that Eros could have a surface of fluffy dust. "If the
satellite lands in
the right place, it might be more like falling on to a feather
mattress than
a concrete floor," he said.
"Very appropriately, the satellite got to Eros on
Valentine's day. Now at
last we are going to kiss it properly."
Copyright 2001, The Guardian
===============
(3) CALL FOR OBSERVATIONS: THE JANUARY COMA BERENICIDS
From Alastair McBeath <mcbal.gwyvre@virgin.net>
[as posted on the IMO mailing list]
Call for Observations, 2001 January 20-26: The January Coma
Berenicids
By Roberto Gorelli and Alastair McBeath
We have recently identified a possible new minor shower, with a
radiant
perhaps only periodically active between January 20-26 or so, in
Coma
Berenices or a neighbouring constellation. This shower may be
associated
with the poorly-observed Comet Lowe 1913 I, seen definitely and
briefly
at only a single return, but which may also have been observed,
again rather
badly, in 1750. The computed shower parameters suggest a radiant
near alpha
= 188 degrees, delta = +22 degrees, producing its maximum
activity around
January 24 (solar longitude = 304.2-305.0 degrees, eq.
J2000.0). The meteors would be swift-moving, with an atmospheric
velocity of
59 km/s, similar to the Perseids of July-August. [...]
We have provisionally called this source the January Coma
Berenicids to
differentiate it from the "other" Coma Berenicids
active from about December
12-January 23, peaking towards December 20, as we suspect the two
are
actually separate showers, though this is uncertain as yet. Some
visual and
radio January Coma Berenicid activity seems present in the
reports we have
checked, but not necessarily in every year. A radio peak
coinciding in time
with several visual fireballs (the source of these is unknown
however)
occurred on 1998 January 24-25, for instance, while two Slovenian
observers
reported a small visual outburst perhaps from near Corona
Borealis on 1999
January 21-22. A further possible outburst may have occurred on
2000 January
20-21, noted by a single UK witness (this possible radiant may
have been
north-west of Ursa Major though, not south-east of it). The 1999
and 2000
events may both have been weakly present in the radio results
too.
As new Moon falls on January 24, conditions are perfect for
checking in
2001, and we would urge all observers who can to watch for
whatever happens.
Although January 23-24 and 24-25 are probably the most important
dates to
cover, other dates between January 20-26 should not be ignored if
the sky is
clear. Standard IMO visual plotting watches should be carried out
as normal
at this time of year, and any possible January Coma Berenicids
identified as
such after the observation, assuming an unusual level of activity
is not
apparent in the field. Ideally, video or photographic techniques
should be
employed too, since we need to establish the presence of any
radiant(s) and
the orbital parameters for any meteors connected to this source.
From
northern hemisphere sites, the proposed radiant is well on-view
from about
22h30m-23h local time, culminating shortly before dawn.
Circumstances are
less favourable well south of the equator, where the radiant can
be clearly
observed only after 01h30m-02h local time. All data, even
negative results
(that is, where observations were made with clear skies, but no
possible
January Coma Berenicids were seen), would be useful, remembering
we know
almost nothing about this possible shower.
We would also like anyone with data on meteor activity from this
part of
January from before Comet Lowe's discovery onwards to let us know
if any
possible radiant is indicated around the Coma to Corona region,
especially
where any orbital characteristics for the meteors could be
established. In addition we would urge anyone with access to the
appropriate
information to check for prediscovery images of Comet Lowe taken
in the
Virgo region in December 1912.
All reports should be submitted to the appropriate IMO
Commissions as
normal, but the present authors would be pleased to receive
copies of any
data from the January 20-26 period separately too, for rapid
analysis. This
applies both to 2001 results and any from previous years.
Further information on the possible January Coma Berenicids can
be found in
our article in the December 2000 issue of the IMO's journal
"WGN". Further
to our acknowledgements there, we are grateful to David Asher and
Mark
Bailey of Armagh Observatory for forwarding the 2000 January
20-21 report to
us, noted above. This, with the Slovenian observations, decided
us to extend
the investigated period beyond the dates originally suggested in
our "WGN"
article.
Good luck, and clear skies!
E-mail addresses:
Roberto Gorelli: <md6648@mclink.it>
Alastair McBeath: <vice_president@imo.net>
============
(4) NASA SEEKS CRATER RATERS
From The BBC News Online, 9 January, 2001
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1108000/1108119.stm
By BBC News Online internet reporter Mark Ward
Nasa is looking for space enthusiasts to help it find and
classify craters
on Mars.
Scientists at the American space agency's Ames Research Center
want to
recruit "clickworkers" who are happy to spend time
looking through a series
of images of the Martian surface and rating the craters they
find.
Nasa is turning to people to do the job because they tend to be
more
discriminating than computer software designed for the same task.
If the pilot project proves successful, the clickworkers could be
asked to
help the agency process the huge amounts of data from Nasa's
present and
future Martian probes.
Crater clues
Late last year, a smaller experiment was started that asked
people to
classify craters photographed by the Viking Orbiter in 1976.
The test project used data that had already been studied to see
if the
layman was as good at spotting and classifying craters as Nasa's
own
scientists.
The rate at which craters degrade tells experts a lot about how
geologically
active a planet is and when and if water flowed on its surface.
More generally, craters can give clues about a planet's
development and what
future probes should be looking for.
Initially, in the new pilot study, clickworkers will be asked to
look at
images of the Martian surface, estimated to show 42,000 craters
in a
latitudinal band 30 degrees north to 30 degrees south.
Good job
The classifications by different clickworkers will be collated to
ensure the
ratings are consistent. It will also be established how many
times an image
has to be checked before results are reliable.
Bob Kanefsky, the Nasa software engineer running the web part of
the
project, said that, although some crater-raters missed some very
faint
features, generally they did a good job.
Results from the project will be presented to other planetary
scientists in
a few months, he said.
"We'll see if the idea catches on and researchers decide to
use this idea
for other types of space data analysis."
Copyright 2001, BBC
=============
(5) NEO-EXPERT & CCNet MEMBER, GENERAL PETE WORDEN THE NEXT
NASA
ADMINISTRATOR? GOOD LUCK, PETE!
From NASA Watch, 8 January 2001
http://www.nasawatch.com/
NEW NAMES SURFACE AS POSSIBLE NASA ADMINISTRATOR
In the wake of Monday's false alarm/cancelled announcements from
the Bush
Transition Team (it depends on who you talk to) more names are
starting to
surface as possible candidates/choices for NASA Administrator. In
addition
to former Senator Harrison Schmitt (R-NM) whose name has been in
the news as
a possible choice for NASA Administrator since mid-December the
names of
former Senator Jake Garn (R-UT), Brigadier General S. Pete
Worden, and Rep.
Ralph Hall (D-TX) are now "in play". Sources tell NASA
Watch that Garn, who
flew as a Payload Specialist on Shuttle mission STS-51D, has been
contacted
by the Bush Transition Team. Worden is Deputy Director for
Command and
Control for the United States Air Force at the Pentagon. Rep.
Ralph Hall is
the ranking minority member on the House Science Committee and is
a long
time friend of the Bush family. He was apparently offered the
position of
Energy Secretary but turned down the offer.
=============
(6) ELEVEN NEW MOONS FOR JUPITER
From Ron Baalke <baalke@zagami.jpl.nasa.gov>
Institute for Astronomy
University of Hawaii
Honolulu, Hawaii
Contacts:
Dr. David Jewitt
phone 808 956 6664; email: jewitt@ifa.hawaii.edu
Mr. Scott Sheppard
phone 808 956 6098; email: sheppard@ifa.hawaii.edu
Mrs. Karen Rehbock
phone 808 956-6829; email: rehbock@ifa.hawaii.edu
Web Site: http://www.ifa.hawaii.edu/faculty/jewitt/jmoons/jmoons.html
FOR IMMEDIATE RELEASE: January 8, 2001
ELEVEN NEW MOONS FOR JUPITER
University of Hawaii Institute for Astronomy scientists report
their
discovery of 11 new satellites of Jupiter, all members of
Jupiter's outer
"irregular" satellite system. These observations double
the number of such
moons known to orbit the planet and are the largest number of
satellites
ever discovered at one time. Ten of the discoveries were
announced on
January 5 on International Astronomical Union Circular IAUC 7555.
The 11th
was announced at the end of November on IAUC 7525.
Discovery
The satellites were discovered during a systematic search of the
space near
Jupiter conducted at the University of Hawaii 88 inch (2.2 meter)
telescope
atop Mauna Kea. The team, lead by IfA graduate student Scott
Sheppard and
Professor David Jewitt, and aided by Drs. Yan Fernandez
and Eugene Magnier, used a large format charge-coupled device
(CCD) camera
(the "8K") to obtain a wide field of view. The CCD
produces digital images
that can be conveniently analyzed using computers. The observing
strategy
was to obtain 3 images of each position in order to search for
objects
moving against the star and galaxy background. Objects near
Jupiter move
with a characteristic slow speed that helps us to distinguish
them from
foreground asteroids and background Kuiper Belt Objects.
One of the 11 new satellites turns out to have been a previously
observed
but long-lost object S/2000 J1. The other 10 have not been
previously seen.
Sizes of the Satellites
The sizes of the satellites are not well known because their
albedos (the
surface reflectivities) are unmeasured. However, crude estimates
based on
the apparent brightnesses in our data and on an assumed albedo of
4% place
the diameters in the range 3 to 8 km. Because the albedos are
probably not
less than 4%, the sizes are probably not larger than those
obtained here.
The Orbits
The newly discovered satellites follow "irregular
orbits", meaning that
their orbits are large, eccentric and inclined to Jupiter's
equator.
Satellites S/2000 J2 - J10 have orbital radii about 300 times the
radius of
Jupiter and inclinations near 150 to 160 degrees, meaning that
they are
retrograde. These objects join the 5 previously known retrograde
satellites
of Jupiter, bringing the total number of such objects to 14.
New satellite S/2000 J11 falls in the prograde irregular group,
with orbital
radii near 150 Jupiter radii and inclinations near 30 degrees. A
total of 5
such objects are now known.
Lastly, S/2000 J1 occupies neither of the previously known
dynamical
clusters, with orbital radius near 100 Jupiter radii and
inclination 45
degrees.
Origin of the Satellites
Irregular satellites are thought to have been captured from
heliocentric
orbit when Jupiter was young. The best evidence for this
hypothesis is that
the orbits of some of the irregular moons are actually retrograde
(meaning,
they orbit the planet in a direction opposite to Jupiter's
rotation).
Essentially the only plausible way to produce irregular
satellites is by
capture. However, it is not easy for Jupiter (or any other
planet) to
directly capture passing asteroids from heliocentric orbit. In
general, some
of the initial energy of the heliocentric objects must be
dissipated so that
Jupiter can hold on to it. The origin of the dissipation that
lead to the
capture of Jupiter's irregular satellites is unknown. In fact, at
the
present time there is no plausible source of dissipation so that
capturing
satellites is presently almost impossible. It is theorized,
however, that
the youthful Jupiter sustained a bloated atmosphere that extended
far above
the cloud tops of the present planet. Friction with this
atmosphere could
have captured the irregular satellites. In possible support of
this
hypothesis, we note that some of the satellites belong to
dynamical groups
or families with similar semi-major axes and inclinations.
Perhaps these
families were formed when initial bodies broke up on capture, due
to the
pressure exerted by impact with the extended atmosphere.
The Institute for Astronomy at the University of Hawaii conducts
research
into galaxies, cosmology, stars, planets, and the Sun. Its
faculty and staff
are also involved in astronomy education, and in the development
and
management of the observatories on Haleakala and Mauna Kea. Refer
to the IfA
Web site for more information, http://www.ifa.hawaii.edu/
.
============
(7) IMPACTS AND EARTH EVOLUTION
From Margaret Penston <mjp@ast.cam.ac.uk>
The RAS 2000 Harold Jeffreys Lecture
Professor Richard Grieve, Natural Resources Canada
'Imacts and Earth Evolution'
Friday 12 January 2001, Scientific Societies Lecture Theatre,
Savile Row,
London. The lecture will begiven at the Astronomy &
Geophysics (Ordinary
Meeting) 16.00-18.00
Abstract:
The Earth is the most geologically active of the terrestrial
planets, with a
surface that is constantly renewing itself. As a result, it
has preserved
only a relatively small and biased sample of the population of
terrestrial
impact craters that were formed throughout geologic time.
This sample, however, provides important ground-truth data for
understanding
large-scale impact processes. Terrestrial impacts are also
responsible for,
at least, one global mass extinction event in the biosphere and
several
world-class hydrocarbon and mineral resource deposits. It is
speculated that
they could also have had a role in the formation of the earliest
secondary,
felsic crust of the Earth.
==============
(8) ENVIRONMENTAL EFFECTS OF IMPACTS
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
I recently updated my table summarising the environmental effects
of large
asteroid impacts:
http://www4.tpg.com.au/users/tps-seti/climate.htm
Comments are welcome.
regards
Michael Paine
============
(9) ARCHAEO-ASTRONOMERS MAY HAVE BEEN FOOLED BY 20th-CENTURY
STONEHENGE
DESIGN
From The Independent, 9 January 2001
http://www.independent.co.uk/news/UK/Science/2001-01/shenge090101.shtml
Stonehenge stands proud as very model of a 20th-century facelift
By Steve Connor, Science Editor
9 January 2001
A new visitors' guidebook to Stonehenge may describe how most of
the stone
monoliths have been moved or set in concrete during restoration
work done in
the 20th century.
English Heritage said yesterday that it was considering
describing the full
extent of the work because of claims that the public has been
kept in the
dark about the true extent of the alterations.
"The Stonehenge visitors' guidebook is due to be updated and
we will be
considering what happened during the 20th century, but no
decision has been
made," said Elspeth Henderson, a spokeswoman for English
Heritage.
Brian Edwards, a researcher at the University of the West of
England in
Bristol, claims that the Stonehenge of today bears little
resemblance to the
original Stonehenge because of changes made in the past 100
years.
He claims that many of the stones have been lifted or
straightened and that
some have even been set in concrete. "What we have been
looking at is a
20th-century landscape. It has been created by the heritage
industry and is
not the creation of prehistoric peoples," Mr Edwards said.
"I've always
thought that if people bother to make the trip to Stonehenge,
from home or
abroad, then the least they should expect is a true story."
English Heritage, however, denied that there had been any attempt
to cover
up the work, which it says was done after thorough archaeological
excavations.
"What was carried out in the 20th century was structural
stabilisation
work," Ms Henderson said. "To say that we are trying to
cover this up in
some way is just not true."
Christopher Chippindale, the acting director of the Cambridge
University
Museum of Archaeology and Anthropology, confirmed that most of
the stones
had been moved in some way over the past 100 years.
Copyright 2001, The Independent
===============
(10) THE ETHICAL DIMENSIONS OF SPACE SETTLEMENT
Fogg MJ. The ethical dimensions of space settlement
SPACE POLICY 16: (3) 205-211 AUG 2000
While proposals for settling in the space frontier have appeared
in the
technical literature for over 20 years, it is in the case of Mars
that the
ethical dimensions of space settlement have been most studied.
Mars raises
the questions of the rights and wrongs of the enterprise more
forcefully
because: (a) Mars may possess a primitive biota; and (b) it may
be possible
to terraform Mars and transform the entire planet into a living
world. The
moral questions implicit in space settlement are examined below
from the
standpoints of four theories of environmental ethics:
anthropocentrism,
zoocentrism, ecocentrism and preservationism. In the absence of
extraterrestrial life, only preservationism concludes that space
settlement
would be immoral if it was seen to be to the benefit of
terrestrial life.
Even if Mars is not sterile, protection for Martian life can be
argued for
either on intrinsic or instrumental grounds from the standpoints
of all of
these theories. It is argued further that a strict
preservationist ethic is
untenable as it assumes that human consciousness, creativity,
culture and
technology stand outside nature, rather than having been a
product of
natural selection. If Homo sapiens is the first spacefaring
species to have
evolved on Earth, space settlement would not involve acting
'outside
nature', but legitimately 'within our nature'. (C) 1999
International
Astronautical Federation or the International Academy of
Astronautics.
Published by Elsevier Science Ltd. All rights reserved.
Addresses:
Fogg MJ, Probabil Res Grp, 44 Hogart Court, Fountain Dr, London
SE19 1UY,
England.
Probabil Res Grp, London SE19 1UY, England.
Copyright © 2001 Institute for Scientific Information
=================
(11) AND FINALLY: MOON HOAX SPURS CRUSADE AGAINST BAD ASTRONOMY
From The New York Times, 11 January 2001
http://www.nytimes.com/2001/01/11/science/11WIRE-SPACE.html
Moon Hoax Spurs Crusade Against Bad Astronomy
By REUTERS
AN DIEGO, Jan 10 - The myth about equinox eggs got him started,
misinformation about meteors bugged him, but when he learned that
some
people think the Apollo Moon landings never happened, Philip
Plait knew the
time had come for his crusade against bad astronomy.
So what began as a frustrated astronomy graduate student's online
fuming has
evolved into a newspaper column, a book contract and a Web site
that gets an
average of 15,000 hits a week: http://www.badastronomy.com.
No one is spared on the site: Plait, who holds a doctorate in
astronomy from
the University of Virginia and worked with the Hubble Space
Telescope, takes
aim at movies, television, the news media and the Internet when
they trample
on what he considers to be the obvious truths about space
science.
Take, for example, the notion that humans never walked on the
Moon, despite
copious evidence to the contrary.
"People believe in the weirdest stuff, but they don't
believe the most
flaming obvious thing that's right in front of their face and I
get e-mail
about this," Plait said in an interview at the annual
meeting of the
American Astronomical Society in San Diego.
He blames much of it on the movie ``Capricorn One,'' a science
fiction
offering in which a planned human mission to Mars is faked.
``It's a good flick, but it legitimized a lot of these people who
claimed we
never went to the Moon,'' Plait said. ``There weren't that many
people, but
with the Web, you can spread disinformation instantly. People are
just
willing to grab onto this stuff.''
Where Are the Stars in Moon Photos?
One common argument used by the anti-Apollo folks is that in
photographs of
astronauts on the lunar surface, no stars can be seen in the dark
sky,
therefore the pictures must have been taken on Earth somewhere.
Plait literally gagged as he recounted this, and countered with
what to him
was the obvious fact: there are no stars in the pictures from the
moon
because the Moon itself is being blasted with sunlight and is
enormously
bright, so bright that people on Earth can sometimes read by the
light of
the full Moon.
``When they're taking a picture of this brightly lit astronaut on
a brightly
lit landscape, it's just like taking a picture in daytime here on
the
earth,'' he said. ``No stars have a prayer of getting through
that.''
Rather that debunking this idea on his Web site, Plait has a
section
referring visitors to other sites of ``debunkers'' and
``conspiracy
theories.'' But he plans a chapter in an upcoming book to be
called ``Bad
Astronomy'' on this question.
There will also be a chapter on those who calculate the birth of
the
universe using the Bible, estimating its age in the thousands of
years,
instead of the billions of years that astronomers have long
maintained.
``Astronomy is one of the most accessible sciences,'' he said.
``Everybody
wonders about it and it does tap into the fundamental questions
of humanity
-- why are we here, what's our place in the universe, does the
universe have
an end, how did it start -- these aren't little questions, whole
religions,
trillion-dollar-a-year industries are based on these questions.
``But it means that there's an open door into people's heads. If
you can use
that pathway to get to people, it's a good way to do it, for ill
or for
good,'' Plait said.
Beginning in his student days in 1993 and 1994 with a personal
Web site as
his platform, Plait expressed irritation at a commonly held
belief: that
eggs can only be stood on end at the exact moment of vernal
equinox.
That, said Plait, is just plain nonsense. And he said so on his
site,
eventually featuring a picture of a gaggle of eggs at attention,
taken on
Oct. 25 -- as he said, about as far from the vernal equinox as
possible.
He did not hit on the idea of creating a Web site about bad
astronomy until
1998, several months before a Leonid meteor shower. It turned out
to be good
timing: there was plenty of media grist for his mill in that
event.
Plait has not quit his day job: he currently works in California
on public
education programs for the Gamma Ray Large Area Space Telescope.
He also
writes a column for the German newspaper, Frankfurter Allgemeine
Zeitung.
Copyright 2001, New York Times
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CCNet SPECIAL: THE PANSPERMIA/BIOGENESIS DEBATE, 11 January
2001
-----------------------------------------------------------------
"Geological evidence suggests that Earth may have had
surface water
-- and thus conditions to support life -- billions of years
earlier than
previously thought. [...] "This appears to be evidence of
the
earliest existence of liquid water on our planet. If water
occurred this
early in the evolution of earth, it is possible that primitive
life, too,
occurred at this time."
--Margaret Leinen, National Science Foundation, 10 January
2001
"But proponents of panspermia do not start thus. Current
success
lies in establishing that if there was DNA-life on early Mars -
or
other solar system body - it would probably, or inevitably,
transfer
to the Earth."
--Max Willis, 10 January 2001
"As for whether the universe really is bio-friendly, I
confess I
find that idea philosophically appealing. But at the end of the
day, the
question is a scientific one, and must be settled on scientific
grounds. The easiest way to establish bio-friendliness would be
to find a
second genesis - an example of life forming independently on
another planet.
Unfortunately our best hope for achieving this, which is to
discover truly
novel life forms on Mars, has probably been compromised by
cross-contamination."
--Paul Davies, 10 January 2001
(1) RE-DATING THE ORIGIN OF TERRESTRIAL LIFE: NEW GEOLOGICAL
EVIDENCE THROWS
CURRENT VIEWS ON EARLY EARTH INTO QUESTION
Andrew Yee <ayee@nova.astro.utoronto.ca>
(2) EARTH'S OLDEST MINERAL GRAINS SUGGEST AN EARLY START FOR LIFE
NASA Astrobiology News, 11 January
(3) EXTRATERRESTRIAL DELIVERY OF WATER ON THE EARTH
A. Morbidelli et al.
(4) EXOBIOLOGICAL PROSPECTING
E. Newton et al.
(5) ACCRETION OF EARLY MICROMETEORITES DURING THE HEAVY
BOMBARDEMENT
M. Maurette et al.
(6) METEORS: DELIVERY MECHANISM OF ORGANIC MATTER TO THE EARTH
P. Jenniskens et al.
(7) PANSPERMIA SCIENCE VS. OCKHAM/DRAKE/DAVIES PHILOSOPHY
Max Wallis <wallismk@Cardiff.ac.uk>
(8) ON SCIENCE & PHILOSOPHY IN ASTROBIOLOGY
Paul Davies <pcwd@camtech.net.au>
(9) AND FINALLY: FIRST CELLS, THAN SPECIES, NOW THE WEB
The New York Times, 26 Dec 2000
================
(1) RE-DATING THE ORIGIN OF TERRESTRIAL LIFE: NEW GEOLOGICAL
EVIDENCE THROWS
CURRENT VIEWS ON EARLY EARTH INTO QUESTION
From Andrew Yee <ayee@nova.astro.utoronto.ca>
National Science Foundation
Washington, D.C.
Media contact: Cheryl Dybas, (703) 292-8070, cdybas@nsf.gov
Program contact: Sonia Esperanca, (703) 292-8554, sesperan@nsf.gov
Embargoed until 2 p.m. EST, January 10, 2001
NSF PR 01-02
Earlier Water on Earth? Oldest Rock Suggests Hospitable Young
Planet
Geological evidence suggests that Earth may have had surface
water -- and
thus conditions to support life -- billions of years earlier than
previously
thought. Scientists reconstructed the portrait of early Earth by
reading the
telltale chemical composition of the oldest known terrestrial
rock. The
4.4-billion-year-old mineral sample suggests that early Earth was
not a
roiling ocean of magma, but instead was cool enough for water,
continents,
and conditions that could have supported life. The age of the
sample may
also undermine accepted current views on how and when the moon
was formed.
The research was supported in part by the National Science
Foundation (NSF),
and is published in this week's issue of the journal Nature.
"This appears to be evidence of the earliest existence of
liquid water on
our planet," says Margaret Leinen, assistant director of NSF
for
geosciences. "If water occurred this early in the evolution
of earth, it is
possible that primitive life, too, occurred at this time."
By probing a tiny grain of zircon, a mineral commonly used to
determine the
geological age of rocks, scientists from the University of
Wisconsin-Madison, Colgate University, Curtin University in
Australia and
the University of Edinburgh in Scotland have found evidence that
4.4 billion
years ago, temperatures had cooled to the 100-degree Centigrade
range, a
discovery that suggests an early Earth far different from the one
previously
imagined.
"This is an astounding thing to find for 4.4 billion years
ago," says John
Valley, a geologist at UW-Madison. "At that time, the
Earth's surface should
have been a magma ocean. Conventional wisdom would not have
predicted a
low-temperature environment. These results may indicate that the
Earth
cooled faster than anyone thought." Previously, the oldest
evidence for
liquid water on Earth, a precondition and catalyst for life, was
from a rock
estimated to be 3.8 billion years old.
The accepted view on an infant Earth is that shortly after it
first formed
4.5 to 4.6 billion years ago, the planet became little more than
a swirling
ball of molten metal and rock. Scientists believed it took a long
time,
perhaps 700 million years, for the Earth to cool to the point
that oceans
could condense from a thick, Venus-like atmosphere. For 500
million to 600
million years after the Earth was formed, the young planet was
pummeled by
intense meteorite bombardment. About 4.45 billion years ago, a
Mars-size
object is believed to have slammed into the Earth, creating the
moon by
blasting pieces of the infant planet into space.
The new picture of the earliest Earth is based on a single, tiny
grain of
zircon from western Australia found and dated by Simon Wilde, of
the School
of Applied Geology at Curtin University of Technology in Perth,
Western
Australia. Valley worked with William Peck, a geologist at
Colgate
University, to analyze oxygen isotope ratios, measure rare earth
elements,
and determine element composition in a grain of zircon that
measured little
more than the diameter of two human hairs. Colin Graham's
laboratory
analyzed the zircon to obtain the oxygen isotope ratios. Graham
is a
contributor to the paper and geochemist at the University of
Edinburgh.
"What the oxygen isotopes and rare earth analysis show us is
a high oxygen
isotope ratio that is not common in other such minerals from the
first half
of the Earth's history," Peck says. In other words, the
chemistry of the
mineral and the rock in which it developed could only have formed
from
material in a low-temperature environment at Earth's surface.
"This is the first evidence of crust as old as 4.4 billion
years, and
indicates the development of continental-type crust during
intense meteorite
bombardment of the early Earth," Valley says. "It is
possible that the
water-rock interaction (as represented in the ancient zircon
sample) could
have occurred during this bombardment, but between cataclysmic
events."
Scientists have been searching diligently to find samples of the
Earth's
oldest rocks. Valley and Peck say such ancient samples are
extremely rare
because rock is constantly recycled or sinks to the hot mantle of
the Earth.
Over the great spans of geologic time, there is little surface
material that
has not been recycled and reprocessed in this way.
The tiny grain of zirconium silicate or zircon found by Wilde in
western
Australia was embedded in a larger sample containing fragments of
material
from many different rocks, Valley says. Zircons dated at 4.3
billion years
were reported from the same site a decade ago, but the new-found
zircon
grain is more than 100 million years older than any other known
sample,
giving scientists a rare window to the earliest period of the
Earth.
"This early age restricts theories for the formation of the
moon," Valley
says. "Perhaps the moon formed earlier than we thought, or
by a different
process." Another intriguing question is whether or not life
may have arisen
at that early time. Low temperatures and water are preconditions
for life.
The earliest known biochemical evidence for life and for a
hydrosphere is
estimated at 3.85 billion years ago, and the oldest microfossils
are 3.5
billion years old.
"It may have been that life evolved and was completely
extinguished several
times" in catastrophic, meteorite-triggered extinction
events well before
that, Valley says. The research conducted by Valley, Peck, Graham
and Wilde
was also supported by the U.S. Department of Energy, the U.K.
Natural
Environment Research Council and a Dean Morgridge Wisconsin
Distinguished
Graduate Fellowship.
-NSF-
Note to reporters and editors
For images of the rock and crystal, see:
http://www.nsf.gov/od/lpa/news/press/01/pr0102.htm
Editors: A high-resolution image is available for downloading at:
http://www.news.wisc.edu/newsphotos/zircon.html.
See also: Time line graphic at
http://www.news.wisc.edu/newsphotos/oldrock.html
IMAGE CAPTIONS:
[Image 1: http://www.news.wisc.edu/newsphotos/zircon.html]
Cathodoluminescence image of the oldest known material from the
Earth, a
single crystal of zircon from the Jack Hills metaconglomerate,
Western
Australia. Concentric, magmatic growth zoning is shown about the
crystal
core. The crystallization age of 4.40Ga (4004 +/- 4Ma) was
determined from
the circled area by ion microprobe. The arrow points to an
inclusion of
quartz. The high oxygen isotope ratio from this sample suggests
that low
temperature surficial processes including liquid water were
important for
the formation of protoliths to this magma."
[Image 2: http://www.nsf.gov/od/lpa/news/press/01/pr0102.htm]
False color backscattered electron image of the 4.40Ga zircon.
Ion
microprobe pits are visible as are 3 inclusions of quartz (black
spots,
10-20 microns in diameter).
[Image 3: http://www.nsf.gov/od/lpa/news/press/01/pr0102.htm]
False color cathodoluminescence image of the 4.40Ga zircon
showing
concentric, magmatic growth zoning.
============
(2) EARTH'S OLDEST MINERAL GRAINS SUGGEST AN EARLY START FOR LIFE
From NASA Astrobiology News, 11 January
http://nai.arc.nasa.gov/index.cfm?page=zircons
Microscopic view of a zircon crystal determined to be 4.4 billion
years old.
Photo: John W. Valley, University of Wisconsin, Madison
Scientists are drawing a portrait of how Earth looked soon after
it formed
4.56 billion years ago, based on clues within the oldest mineral
grains ever
found.
Tiny zircons (zirconium silicate crystals) deposited in ancient
stream
deposits appear to indicate that Earth developed continents and
water --
perhaps even oceans and environments in which microbial life
could emerge --
4.3 billion to 4.4 billion years ago.
The findings by two research groups, one in Australia and the
other in the
US, indicate "liquid water stabilizes early on Earth-type
planets," said
geologist Stephen Mojzsis, a member of the NASA Astrobiology
Institute's
University of Colorado, Boulder, team. "This increases the
likelihood of
finding life elsewhere in the universe" by suggesting that
conditions
conducive to life can develop faster and more easily than
previously
thought.
FULL STORY at http://nai.arc.nasa.gov/index.cfm?page=zircons
===========
(3) EXTRATERRESTRIAL DELIVERY OF WATER ON THE EARTH
Morbidelli A, Chambers J, Lunine JI, Petit JM, Robert F,
Valsecchi GB, Cyr
KE. Source regions and timescales for the delivery of water to
the Earth
METEORITICS & PLANETARY SCIENCE 35: (6) 1309-1320 NOV 2000
In the primordial solar system, the most plausible sources of the
water
accreted by the Earth were in the outer asteroid belt, in the
giant planet
regions, and in the Kuiper Belt. We investigate the implications
on the
origin of Earth's water of dynamical models of primordial
evolution of solar
system bodies and check them with respect to chemical
constraints. We find
that it is plausible that the Earth accreted water all along its
formation,
from the early phases when the solar nebula was still present to
the late
stages of gas-free sweepup of scattered planetesimals. Asteroids
and the
comets from the Jupiter-Saturn region were the first water
deliverers, when
the Earth was less than half its present mass. The bulk of the
water
presently on Earth was carried by a few planetary embryos,
originally formed
in the outer asteroid belt and accreted by the Earth at the final
stage of
its formation. Finally, a late veneer, accounting for at most 10%
of the
present water mass, occurred due to comets from the
Uranus-Neptune region
and from the Kuiper Belt. The net result of accretion from these
several
reservoirs is that the water on Earth had essentially the D/H
ratio typical
of the water condensed in the outer asteroid belt. This is in
agreement with
the observation that the D/H ratio in the oceans is very close to
the mean
value of the D/H ratio of the water inclusions in carbonaceous
chondrites.
Addresses:
Morbidelli A, Observ Cote Azur, F-06003 Nice, France.
Observ Cote Azur, F-06003 Nice, France.
Armagh Observ, Armagh BT61 9DG, North Ireland.
Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA.
Museum Hist Nat, Paris, France.
Ist Astrofis Spaziale, Rome, Italy.
NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston,
TX 77058
USA.
Copyright © 2001 Institute for Scientific Information
==============
(4) EXOBIOLOGICAL PROSPECTING
Newton E, Edwards HGM, Wynn-Williams D, Hiscox JA. Exobiological
prospecting
ASTRONOMY & GEOPHYSICS 41: (5) 28-30 OCT 2000
Several emerging technologies are being investigated for
detecting potential
extraterrestrial microbial life, either extinct and/or extant
(living).
These technologies are particularly relevant for future
exobiological
searches on Mars and Europa, the two most promising candidates in
this solar
system for harbouring extraterrestrial life. Two systems are
discussed: ATP
measurement and Raman spectroscopy. In particular, experiments
are described
in which samples from Antarctica (an analogue environment for
ancient Mars)
have been analysed using Raman spectroscopy. This technology is
perhaps the
most versatile for searching for both extinct and extant
organisms.
Addresses:
Hiscox JA, Univ Reading, Sch Anim & Microbial Sci, POB 228,
Reading RG6 6AJ,
Berks, England.
Univ Reading, Sch Anim & Microbial Sci, Reading RG6 6AJ,
Berks, England.
Univ Bradford, Bradford BD7 1DP, W Yorkshire, England.
British Antarctic Survey, Cambridge CB3 0ET, England.
Copyright © 2001 Institute for Scientific Information
================
(5) ACCRETION OF EARLY MICROMETEORITES DURING THE HEAVY
BOMBARDEMENT
Maurette M, Duprat J, Engrand C, Gounelle M, Kurat G, Matrajt G,
Toppani A.
Accretion of neon, organics, CO2, nitrogen and water from large
interplanetary dust particles on the early Earth
PLANETARY AND SPACE SCIENCE 48: (11) 1117-1137 SEP 2000
Large interplanetary dust particles (micrometeorites) with sizes
of 100-200
mum, recovered from the Greenland and Antarctica ice sheets,
represent by
far the dominant source of primitive extraterrestrial material
accreted by
the Earth today. Comparisons of mineralogical, chemical and
isotopic
analyses of micrometeorites and meteorites indicate that
micrometeorites are
mostly related to the relatively rare group (2% of the meteorite
falls) of
the primitive hydrous-carbonaceous meteorites, and not to the
most abundant
classes of the ordinary chondrites and differentiated meteorites.
But there
are differences between these two classes of extraterrestrial
objects, such
as a high pyroxene to olivine ratio, a strong depletion in
chondrules, a
much smaller size of the most refractory components, and a much
higher AIB
(alpha -isobutyric amino acid) to isovaline ratio in
micrometeorites as
compared to meteorites. They indicate that micrometeorites
represent a new
population of solar system objects, not represented as yet in the
meteorite
collections. The major objective of this work is to predict
various effects
of the accretion of early micrometeorites on the Earth during the
period of
heavy bombardment suffered by the Earth-Moon system greater than
or equal to
3.9 Ga ago. The application of a simple arithmetics of accretion
to a
selection of measurements (average contents of neon, carbon,
nitrogen and
water in micrometeorites, and isotopic composition of their Ne
and H), shows
that during the peak of this cataclysmic epoch (sterilization
period) which
occurred just after the formation of the young Earth (4.45 Ga
ago), the
accretion of early micrometeorites did play a major role in the
formation of
the terrestrial atmosphere and oceans. Later on, during the early
life
period (around 4 Ga ago), when liquid water and organics could
condense
and/or survive, micrometeorites were possibly functioning as tiny
chemical
reactors to synthesize the prebiotic molecules required for the
origin of
life. Efforts were made to start reducing the number of major
speculations
in this "early-micrometeorite-accretion" scenario
(EMMAC), which is finally
extended with some confidence to Mars, where the survival of
micrometeorites
upon atmospheric entry looks even more favorable than on the
Earth. (C) 2000
Elsevier Science Ltd. All rights reserved.
Addresses:
Maurette M, CNRS, CSNSM, Batiment 104, F-91405 Orsay, France.
CNRS, CSNSM, F-91405 Orsay, France.
IPN, F-91405 Orsay, France.
Museum Nat Hist, Mineral Petrog Abt, A-1014 Vienna, Austria.
CRPG, F-54051 Vandoeuvre Nancy, France.
============
(6) METEORS: DELIVERY MECHANISM OF ORGANIC MATTER TO THE EARTH
Jenniskens P, Wilson MA, Packan D, Laux CO, Kruger CH, Boyd ID,
Popova OP,
Fonda M. Meteors: A delivery mechanism of organic matter to the
early Earth
EARTH MOON AND PLANETS 82-3: 57-70 2000
All potential exogenous pre-biotic matter arrived to Earth by
ways of our
atmosphere, where much material was ablated during a luminous
phase called
"meteors" in rarefied flows of high (up to 270) Mach
number. The recent
Leonid showers offered a first glimpse into the clusive physical
conditions
of the ablation process and atmospheric chemistry associated with
high-speed
meteors. Molecular emissions were detected that trace a meteor's
brilliant
light to a 4,300 K warm wake rather than to the meteor's head. A
new
theoretical approach using the direct simulation by Monte Carlo
technique
identified the source-region and demonstrated that the ablation
process is
critical in the heating of the meteor's wake. In the head of the
meteor,
organic carbon appears to survive flash heating and rapid
cooling. The
temperatures in the wake of the meteor are just right for
dissociation of CO
and the formation of more complex organic compounds. The
resulting materials
could account for the bulk of pre-biotic organic carbon on the
early Earth
at the time of the origin of life.
Addresses:
Jenniskens P, NASA, Ames Res Ctr, Mail Stop 239-4, Moffett Field,
CA 94035
USA.
NASA, Ames Res Ctr, Moffett Field, CA 94035 USA.
Stanford Univ, Dept Mech Engn, High Temp Gasdynam Lab, Stanford,
CA 94305
USA.
Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA.
RAS, Inst Dynam Geospheres, Moscow 117979, Russia.
Copyright © 2001 Institute for Scientific Information
============================
* LETTERS TO THE MODERATOR *
============================
(7) PANSPERMIA SCIENCE VS. OCKHAM/DRAKE/DAVIES PHILOSOPHY
From Max Wallis <wallismk@Cardiff.ac.uk>
Following the Christmas break, let's summarise the state of the
argument
over Andrew Glikson calling panspermia a "philosophical
notion" (CCNet 1
December 2000).
He accepted that panspermia is a "testable" idea, so
satisfies Popper's
criterion for a scientific hypothesis. It's not (yet) proven, he
says, but
also not (yet) disproved. Glikson prefers the Drake equation,
which has some
philosophical underpinning (ignoring space transfer of life and
relying on
many-point generation). Glikson then used the philosophical
notion of
Ockham's razor, to justify life starting on Earth because it's
here. He also
placed some reliance on quantum-mathematical notions of Paul
Davies, it
being unclear if these are more than philosophical in content
(CCNet 20
December).
It's clearly unwise for people in philosophical glass houses to
throw
stones. Since Glikson ducked my challenge that the Drake equation
is
philosophical (CCNet 18 December), will anyone else defend it?
The Drake equation assumes unconnected planetary systems with a
finite
probability of life arising on an Earth-like planet within the
system
lifetime. "Earth-like" could limit possibilities not
only in planet size and
possession of atmosphere, but also to single stars of
restricted spectral class (relating to size and lifetime) so
could be
expressed by small negative powers of 10. But the major
uncertainty is
whether the probability of life arising by chance is finite or
infinitesimal.
The assumption that it's finite is based on the one observation
of life
existing on Earth, the earliest forms having developed
"spontaneously", ie.
without seeding, in a time that's a fraction of 1 Gyr. That life
hardly
advanced for another 2 Gyr suggests a substantial impediment to
the
development of flora and fauna and perhaps a further
improbability in the
development of intelligent life, to which Drake ascribed a
further factor.
Similarity in the DNA from the most primitive micro-organisms to
the most
advanced suggests this factor is again a small negative power of
10.
The Drake approach could allow us to quantify the term
"infinitesimal" for
life arising by chance in our galaxy, as meaning say under
1/10^10 over 10
Gyr planet lifetime. Glikson's claim for the Drake equation as
"statistical
predictability" presumes that the spontaneous generation
rate is faster than
this. "Spontaneous" means not instantaneous, but that
given suitable
environmental conditions, or sequence of conditions, a living
system
develops from non-living matter. Glikson's further claim
that life abounds
throughout the universe, and by presumption in each galaxy, might
be
quantified as a spontaneous generation rate exceeding 1/10^5 or
1/10^6 per
10 Gyr.
But who can say? As the one observation of life on Earth is
insufficient
evidence, what kind of assumption goes into such a statement - is
it not
"philosophical"?
At one time, scientists were reasonably confident that the
Oparin-Urey
concepts and experiments would indicate conditions that could
lead to the
generation of life, whereupon we are able to argue about the
probability of
those conditions. Not only have the experiments with
primeval model-soups
led to nought, but also the idea that a highly-ordered,
information-rich
system arose by chance out of disorder is problematic. Few
scientists would
nowadays place confidence in that hypothesis. The coacervate drop
idea was
indeed an elegant hypothesis, but falls far, far short in the
context of
modern knowledge of the complexity of the DNA/RNA and enzyme
system.
Can Paul Davies's "Fifth Miracle" rescue Earth-based
generation of life?
Scientists are entitled to be sceptical - and to challenge its
supporters as
to whether their confidence is scientifically or philosophically
based.
So how does one tackle the question - how and where did life
start? Not with
Ockham's razor, but with the modern perspective of primitive
"life" as a
wide range of extremeophile micro-organisms. Very different
scenarios to
Earth-bound soup-ponds energised with electrical discharges can
be imagined.
One extreme would be cold semi-ordered crystalline states,
changing slowly
under gas-surface reactions. As highly complex carbonaceous
compounds seem
to arise in interstellar clouds, that's one location to explore.
But proponents of panspermia do not start thus. Current success
lies in
establishing that if there was DNA-life on early Mars - or other
solar
system body - it would probably, or inevitably, transfer to the
Earth. The
next stage might show that if there were DNA-life 5 Gyr ago in
the pre-solar
neighbourhood (say 10 or 100parsec radius), it would probably, or
inevitably, have "infected" the pre-solar nebula.
Transfer times (or even
diffusion times - Arkhipov, CCNet 21 Dec.) of a few Myr per
parsec are
small.
The idea that the pre-solar nebula was comprised of many times
processed
matter is now accepted. Its heavy elements were nucleosynthetic
products of
the galaxy's early supernovae, condensed as interstellar dust and
processed
in clouds and star-forming events. 12 or 15 Gyr allows time even
for
cross-galaxy inter-mixing. So it's plausible to hypothesise that
the
pre-solar nebula included quantities of biological material, both
sputtered
off planets and processed in clouds.
There's no need for proponents of panspermia to accept the whole
of such a
chain of speculation. But adopting panspermia as a working
hypothesis does
allow us to escape the straightjackets of geocentric thinking and
Drake
equation numerology. We may turn out to be wrong, but
socio-cultural
analysis shows that the panspermia idea has now come of age and
entered
mainstream science!
Max Wallis
wallismk@cf.ac.uk
Cardiff Centre for Astrobiology
===============
(8) ON SCIENCE & PHILOSOPHY IN ASTROBIOLOGY
From Paul Davies <pcwd@camtech.net.au>
Dear Benny,
Whilst I do not wish to take sides in the discussion between Max
Wallis and
Andrew Glikson, I should like to clarify my own position on the
panspermia/biogenesis issue. First I want to make the obvious
point that all
theories of life contain hidden philosophical assumptions. I am
struck by
the fact that when I was a student in the 1960s, few scientists
seriously
entertained the possibility of life beyond Earth. Today, it is
fashionable
to suppose that the universe is
teeming with life. I do not think the scientific evidence has
advanced that
much in the last thirty years, so I put the shift down to a
change in
philosophy.
Life may be common in the universe for two quite different
reasons. The
first is panspermia. If life can propagate between star systems
and even
galaxies without succumbing to the lethal effects of radiation
and other
hazards of outer space, then there could be many planets with
life.
Personally I think the transport of life between near-neighbours,
such as
Mars and Earth, is almost inevitable. But that is because impact
ejecta
provide a relatively safe mode of transport, shielding any
ensconced
microbes from radiation and atmospheric friction. However, since
the chance
of a rock blasted off Earth ever hitting another Earthlike planet
beyond the
solar system is infinitesimal, this mechanism is not a route to
panspermia.
I regard the Hoyle-Wickramasinghe theory, in which naked microbes
remain
viable whilst travelling for millions of years in space, as
extremely
unlikely, though not impossible. It deserves to be tested.
Perhaps
interstellar transport has occurred this way from time to time,
but I doubt
whether it has populated the universe. And for those like myself
whose
primary interest is in the origin of life, panspermia is a
distinctly
unhelpful theory, because it sidesteps the entire issue of how
and where
life ultimately originated.
The second reason why life might be common is if the universe
possesses
bio-friendly laws. By this I mean that matter is fast-tracked to
life
wherever earthlike conditions prevail, making it a "cosmic
imperative," to
use Christian de Duve's evocative description. This notion seems
to be the
prevailing opinion among astrobiologists. An examination of the
known laws
of physics and chemistry fails to provide any evidence for
explicit
bio-friendliness, apart from the well-known general
"anthropic"
coincidences.
A hundred years ago, when life was considered to be some sort of
magic
matter, it was reasonable to expect that there might be a life
principle
manifested in chemical affinities. Today, the living cell is
regarded not as
magic matter, but as an information processing system, so it is
no surprise
that a search for bio-friendliness in chemistry is unrewarding.
If the
universe really is bio-friendly, one might expect to discover
that property
instead in the principles that govern the behaviour of
information.
The science of information, and the study of the relationship
between
information and matter, is still in its infancy, and I remain
open-minded
about whether future research in this field will uncover the
"cosmic
imperative" so eagerly expected. My own contribution to this
debate, for
what it is worth, is to draw attention to the distinctive
properties of
quantum information processing - currently a hot topic with the
new
initiatives aimed at building a workable quantum computer. It
seems to me
plausible that nature may have harnessed the extraordinary
information
processing power of quantum systems to build the first autonomous
information replicators - what we call life.
Max Wallis finds the recent work on quantum information and
entanglement
"mind-boggling," and indeed it is. However, this work
is not suspect. It
forms part of mainstream physics and has a sound experimental
basis.
Contrary to Wallis' assertion, there is no inconsistency between
photon
entangelment and the wave theory of light; indeed, the wave
theory forms the
basis for entanglement.
Wallis also suggests that I espouse a "mystical and even
crazy
interpretation of quantum physics." This is news to me. My
take on quantum
mechanics has always been pretty conservative; I have little time
for the
mystical mumbo-jumbo some people attempt to impute to quantum
weirdness.
Readers in any doubt about this might like to read my little book
"The Ghost
in the Atom," co-authored with Julian Brown, which I hope is
a sober and
balanced survey of the field. However, this is beside the point.
What I am
suggesting in relation to the role of quantum mechanics in the
origin of
life is purely operational, and does not depend on controversies
over
interpretation. If there is disagreement among physicists about
the
information processing properties of entangled quantum systems,
it concerns
not interpretaional matters, but the practicalities of harnessing
quantum
information for technological devices.
I sketched some of my speculations (for that is all they are) on
quantum
physics and life in my book "The Fifth Miracle: the search
for the origin of
life." The title is not intended to suggest that biogenesis
was a genuine
miracle, only that it remains a deep puzzle that perhaps calls
for some
imaginative new line of thought. As for whether the universe
really is
bio-friendly, I confess I find that idea philosophically
appealing. But at
the end of the day, the question is a scientific one, and must be
settled on
scientific grounds. The easiest way to establish bio-friendliness
would be
to find a second genesis - an example of life forming
independently on
another planet. Unfortunately our best hope for achieving this,
which is to
discover truly novel life forms on Mars, has probably been
compromised by
the abovementioned cross-contamination.
I hope these brief remarks set the record straight concerning my
own
scientific and philosophical positions.
Yours sincerely,
Paul Davies
====================
(9) AND FINALLY: FIRST CELLS, THAN SPECIES, NOW THE WEB
From The New York Times, 26 Dec 2000
http://www.nytimes.com/2000/12/26/science/26WEBS.html?pagewanted=all
By GEORGE JOHNSON
As the Internet continues to proliferate, it has become natural
to think of
it biologically as a flourishing ecosystem of computers or a
sprawling brain
of Pentium-powered neurons. However you mix and match metaphors,
it is hard
to escape the eerie feeling that an alien presence has fallen to
earth,
confronting scientists with something new to prod and understand.
The result has been an eruption of papers scrutinizing this
artificial
network and concluding, to many people's surprise, that it may be
designed
according to the same rules that nature uses to spin webs of its
own. The
networks of molecules in a cell, of species in an ecosystem, and
of people
in a social group may be woven on the same mathematical loom as
the Internet
and the World Wide Web.
"We are getting to understand the architecture of
complexity," said Dr.
Albert-Laszlo Barabasi, a physicist at the University of Notre
Dame in
Indiana whose research group has recently published papers
comparing such
seemingly diverse systems as the Internet and the metabolic
networks of
life-sustaining chemical reactions inside cells. The similarities
between
these and other complex systems are so striking, he said,
"it's as if the
same person would have designed them."
At the Polytechnic University of Catalonia in Barcelona, Dr.
Ricard V. Sol
and Jose M. Montoya, theoretical biologists in the Complex
Systems Research
Group, have recently found the same kind of patterns by studying
computer
models of three ecosystems: a freshwater lake, an estuary and a
woods.
"These results suggest that nature has some universal
organizational
principles that might finally allow us to formulate a general
theory of
complex systems," said Dr. Sol , who also works at the Santa
Fe Institute in
New Mexico.
In the past, scientists treated networks as though they were
strung together
at random, giving rise to a homogeneous web in which nodes tended
to have
roughly the same number of links. "Our work illustrates that
in fact the
real networks are far from being random," Dr. Barabasi said.
"They display a
high degree of order and universality that has been rather
unexpected by any
accounts."
As they come together, many networks seem to organize themselves
so that
most nodes have very few links, and a tiny number of nodes,
called hubs,
have many links. The pattern can be described by what scientists
call a
power law. To calculate the probability that a node will have a
certain
number of links, you raise that number to some power, like 2 or
3, and then
take the inverse.
Suppose, for example, that you have a network with 100,000 nodes
that obeys
a power law of 2. To find out how many nodes have three links,
you raise 3
to the second power, which is 9, and then take the inverse. Thus
one-ninth
of the nodes, or about 11,111, will be triple linked. How many
will have 100
links? Raise 100 to the second power, and take the inverse: one
ten-thousandth of the 100,000 nodes a total of
10 will be so richly
connected. As the number of connections rises, the probability
rapidly
falls.
This kind of structure may help explain why networks ranging from
metabolisms to ecosystems to the Internet are generally very
stable and
resilient, yet prone to occasional catastrophic collapse. Since
most nodes
(molecules, species, computer servers) are sparsely connected,
little
depends on them: a large fraction can be plucked away and the
network will
endure. But if just a few of the highly connected nodes are
eliminated, the
whole system could crash.
Not everyone believes that a universal law is at hand. A recent
paper by
Boston University physicists found deviations from the power-law
pattern in
a number of different networks, suggesting a more complicated
story. But
even so, the study found hidden orders that were far more
interesting than
the purely random patterns scientists have long used to analyze
networks.
"The important point is that the networks are very different
from our
familiar model systems," said Dr. Mark Newman, a
mathematician at the Santa
Fe Institute. "This means that all our previous theories
have to be thrown
out."
It has only been in recent years that computer power has grown
enough to
gather and analyze data on such intricate systems. In a highly
publicized
paper in 1998, Dr. Duncan Watts, a sociologist at Columbia
University, and
Dr. Steven Strogatz, an applied mathematician at Cornell
University, found
that many networks exhibited what they called the small-world
phenomenon,
popularized in John Guare's play "Six Degrees of
Separation."
Just as any two people can be linked by a chain of no more than
about six
acquaintances, so can any node in a small-world network be
reached from any
other node with just a few hops. The two scientists found this
hidden order
in three networks that could hardly seem more different: the web
of neurons
forming the simple nervous system of the worm Caenorhabditis
elegans, the
web of power stations forming the electrical grid of the Western
United
States and (the finding that attracted the most attention) the
web of actors
who have appeared together in films.
The phenomenon has been popularized by a Web site, the Oracle of
Bacon, at
the University of Virginia's computer science department
(www.cs.virginia.edu/oracle/)
that calculates how closely an actor is linked
to the film star Kevin Bacon. Patrick Stewart of Star Trek fame,
for
example, has a "Bacon number" of 2: he was in "The
Prince of Egypt" with
Steve Martin, who was in "Novocaine" with Kevin Bacon.
More recently Dr. Barabasi, working with a graduate student, Reka
Albert,
and a post-doctoral researcher, Dr. Hawoong Jeong, found that the
World Wide
Web is a small world a phenomenon also noticed by two
researchers at the
Xerox Palo Alto Research Center in California, Dr. Bernardo A.
Huberman and
his student Lada A. Adamic. Any two documents or sites on the Web
are
separated by only a small number of mouse clicks.
The two teams also noted that the Web was structured according to
a power
law, with a handful of highly connected hubs and a steadily
increasing
number of less connected nodes a fact noticed by other groups as
well.
Reaching further, Dr. Barabasi and Ms. Albert found, in a paper
last fall in
Science, that a variety of networks may be organized this way.
Included in
their list were the small worlds of Dr. Watts and Dr. Strogatz as
well as
the connections on a computer chip and a network of citations in
scientific
publications.
The question is how this kind of order arises. In the same paper,
the
Barabasi group proposed a "rich get richer" effect: as
new nodes are added
to a network, they tend to form links with ones that are already
well
connected. New actors are more likely to be cast in films with
well-known
actors. New scientific papers are more likely to cite
well-established ones.
The result, according to their model, is a power-law
distribution.
Their most recent sighting of the pattern was described in the
Oct. 5 issue
of Nature. Dr. Barabasi and his team worked with two members of
the
Northwestern University Medical School department of pathology to
study the
shape of metabolisms, the networks of chemical reactions inside
living
cells. Small molecules are linked to form large molecules, which
are in turn
broken back down into small molecules. But complex as these
networks can be,
they seem to obey a power law. In a paper recently submitted to
the Journal
of Theoretical Biology, Dr. Sol and Dr. Montoya found a
similar pattern in
the ecosystems they studied.
The implication is that all these networks are extremely robust,
shrugging
off most disturbances, but vulnerable to a well-planned assault.
"A random
knockout of even a high fraction of nodes will not damage the
network," Dr.
Barabasi said. "But malicious attacks can."
Suggestive as the new theory is, other scientists are finding
that the
picture may not be so simple. In a paper published in October in
the
Proceedings of the National Academy of Sciences, Dr. Luis A.
Nunes Amaral
and his colleagues at Boston University analyzed a number of
networks,
including some of those studied by the Barabasi group. The list
also
included the hubs and spokes of the world airport system and two
small
friendship networks formed by a group of Mormons and by junior
high school
students. They concluded that while some networks obey power
laws, in many
others the pattern is distorted or nonexistent.
The deviations arise, the study proposed, because it is not
always easy to
add new nodes to a net: actors with more movie credits will
attract more and
more collaborators until they get too old to act at
all. Airports can only
support so many new flights a day. Because of such complications,
a network
may fall somewhere on a spectrum between the extremes of
randomness and
order.
Researchers are optimistic that they will sort out the details of
a
discipline that is still in its infancy. More important than any
particular
study, Dr. Watts said, is that scientists finally have the
computer power to
study real networks instead of just speculating about idealized
ones.
"The real point is not to establish that everything is a
power law," he
said, "but to start modeling complex networks in a way that
is informed by
the data."
Copyright 2000, The New York Times
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