PLEASE NOTE:
*
CCNet 79/2001 - 18 June 2001
---------------------------
"From the enormous increase of recent asteroid discoveries
by
LINEAR, LONEOS, Catalina Sky Survey and Kitt Peak, there seems to
be an
indication that the number of really new discoveries is slowly
decreasing. What is the reason for this? Are we approaching the
end of
asteroid-discovery, assuming that there is a cut-off (gap) in the
distribution of fainter and faintest (main belt) asteroids; or is
it
just the consequence of the fact that most instruments/devices
are
reaching the magnitude below which the observers have at present
not
the possibility to extend their searches towards fainter
asteroids? From
this investigation it follows that we are approaching apparently
the end
of new discoveries, as the consequence of the fact that the more
important
asteroid surveys (in particular, LINEAR) are not searching for
new
asteroids beyond magnitude V=19.5."
--Eric W. Elst, Royal Observatory at Uccle, Belgium
"A rocket could be strapped to the asteroid, they say, and
the
asteroid maneuvered into an immense orbit more than seven times
wider
than the radius of the solar system. The asteroid would then pass
close enough to Earth to tug it gently away from the Sun. (One
hitch, the
authors acknowledge, would be a collision, which would
"sterilize the
biosphere most effectively, at least to the level of
bacteria.")
--Anthony Ramirez, The New York Times, 17 June 2001
(1) BAD NEWS FOR PLANETARY DEFENSE: WE ARE SLOWLY APPROACHING THE
END OF
ASTEROID-DISCOVERY DUE TO OUTDATED SEARCH INSTRUMENTS
http://www.elsevier.nl/gej-ng/10/37/40/42/30/26/abstract.html
(2) CONTOUR TO PROVIDE FIRST SURFACE 'FINGERPRINT' OF COMET
ENCKE'S NUCLEUS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(3) EXTREMELY CLOSE PLUTO APPULSE, POSSIBLE OCCULTATION
DISCOVERED
Ron Baalke <baalke@zagami.jpl.nasa.gov>
(4) THE BURSTING COMET LINEAR
SpaceWeather.com
(5) VENUS IS STANGE: WHAT CAUSED CELESTIAL BACKSPIN?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(6) GEOLOGICALLY RECENT SHALLOW ICE AT MARS' EQUATOR?
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) A COOL IDEA TO SAVE EARTH
The New York Times, 17 June 2001
(8) NASA AIMS TO MOVE EARTH
The Observer, 10 June 2001
(9) MOVING HEAVEN AND EARTH: A COMMENT BY FRED SINGER
S. Fred Singer <singer@sepp.org>
(10) THE K/T MASS EXTINCTION IN THE MARINE REALM: YEAR 2000
ASSESSMENT
http://www.elsevier.nl/gej-ng/10/37/40/42/30/32/abstract.html
(11) SNOWBALL EARTH
Andrew Yee <ayee@nova.astro.utoronto.ca>
(12) RE: CCNet ESSAY: ESTIMATED FLUX OF ROCKS BEARING VIABLE
LIFEFORMS
EXCHNAGED BETWEEN EARTH
Oliver Morton <abq72@pop.dial.pipex.com>
(13) "VIRTUALLY IMPOSSIBLE FOR ANYTHING TO BE EJECTED FROM
THE SURFACE OF A
PLANET BY AN IMPACT "
John Michael Williams <jwill@AstraGate.net>
(14) SHOCK, HORROR: VIRTUALLY IMPOSSIBLE MARS METEORITE FOUND IN
OMAN
Space.com, 17 June 2001
(15) AND FINALLY: YOU HAVE E-MAIL ... FROM SPACE
Discovery News, 18 June 2001
=============
(1) BAD NEWS FOR PLANETARY DEFENSE: WE ARE SLOWLY APPROACHING THE
END OF
ASTEROID-DISCOVERY DUE TO OUTDATED SEARCH INSTRUMENTS
From http://www.elsevier.nl/gej-ng/10/37/40/42/30/26/abstract.html
Planetary and Space Science, Vol. 49 (8) (2001) pp. 781-78628-9
Are we approaching the end of asteroid-discovery?
Eric W. Elst <ericelst@helios.oma.be>
Royal Observatory at Uccle, Ringlaan 3, B-1180 Uccle, Belgium
Received 6 September 2000; accepted 30 January 2001
Abstract
From the enormous increase of recent asteroid discoveries by
LINEAR, LONEOS,
Catalina Sky Survey and Kitt Peak, there seems to be an
indication that the
number of really new discoveries is slowly decreasing. What is
the reason
for this? Are we approaching the end of asteroid-discovery,
assuming that
there is a cut-off (gap) in the distribution of fainter and
faintest (main
belt) asteroids; or is it just the consequence of the fact that
most
instruments/devices are reaching the magnitude below which the
observers
have at present not the possibility to extend their searches
towards fainter
asteroids? From this investigation it follows that we are
approaching
apparently the end of new discoveries, as the consequence of the
fact that
the more important asteroid surveys (in particular, LINEAR) are
not
searching for new asteroids beyond magnitude V=19.5.
Full text supplied by [ScienceDirect]
© Copyright 2001, Elsevier Science, All rights reserved.
===========
(2) CONTOUR TO PROVIDE FIRST SURFACE 'FINGERPRINT' OF COMET
ENCKE'S NUCLEUS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News Service
Cornell University
Contact: David Brand
Office: 607-255-3651
E-Mail: deb27@cornell.edu
FOR RELEASE: June 12, 2001
Instruments aboard CONTOUR spacecraft will provide first surface
'fingerprint' of comet nucleus
ITHACA, N.Y. -- Instruments aboard a spacecraft that will be
launched next
year to explore two, and perhaps three or more, comets in the
solar system
will for the first time provide a "fingerprint" of the
surface of cometary
nuclei, giving the first firm evidence of the composition of the
icy, rocky
objects.
About 50 of the world's leading comet experts, meeting at the
Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.,
recently,
were told that the spacecraft's infrared imaging spectroscopy
will map the
composition of the nucleus of comet Encke at a resolution of 100
meters to
200 meters (109 to 218 yards), detailed enough to see craters and
other
large geologic features and to determine their composition.
Comet Encke will be the first target of NASA's Cornell
University-led Comet
Nucleus Tour (CONTOUR), scheduled for launch July 1, 2002. In a
report
prepared for the meeting, James Bell, Cornell assistant professor
of
astronomy and one of the scientists responsible for the
spectrometer on the
close-up imager, noted that the surface resolution of Encke's
nucleus
by the CONTOUR spectrometer will be even better than that
obtained by the
infrared spectrometer on the Near Earth Asteroid Rendezvous
spacecraft
during its recent orbital mission to asteroid 433 Eros. "The
CONTOUR
spacecraft will come within about 100 to 160 kilometers (62 to
100 miles) of
the nucleus, although the exact distance is still in doubt
because we don't
know the orbital position of the nucleus with extreme
precision," said Bell.
The imaging instrument, called the CONTOUR remote
image/spectrograph, also
will send back digital-camera images of Encke's nucleus. The
camera will
capture the images as the spacecraft speeds through the comet's
dusty,
gaseous head, called the coma, at 28 kilometers (about 17 miles)
a second in
November 2003. Joseph Veverka, Cornell professor of astronomy and
principal investigator on the $155 million mission, noted at the
Cambridge
meeting that "success" will be defined as obtaining
digital images of the
nucleus showing automobile-size details, such as rocks, about 4
meters (4
yards) across. Encke, first discovered 225 years ago, is about 8
kilometers
(5 miles) long and has an average radius of about 2.5 kilometers
(1.5
miles). It orbits the sun once every 3.2 years, and its most
recent
apparition from Earth was last year. It is unique in that it has
been
observed from Earth on 56 of its apparitions, more than any other
comet,
including Halley.
Encke will not be the only comet on CONTOUR's agenda. In June
2006 the
spacecraft is scheduled to encounter Comet Schwassmann-Wachmann 3
and,
possibly, Comet d'Arrest in 2008. These targets are so-called
"Jupiter
family" comets because they are thought to have had their
orbital periods
shortened by previous gravitational encounters with the giant
planet. The
science team hopes it also might be possible to visit other kinds
of comets,
particularly primitive members of the so-called "dynamically
young" family
that are in long elliptical orbits and might be making one of
their first
close passes by the sun.
Cornell senior research associate and science team member Peter
Thomas noted
at the meeting that during the 30-minute flyby of the nucleus,
the
spacecraft's instruments "will be able to obtain detailed
compositional
measurements of gas and dust in the near-nucleus
environment." The comet's
coma is a vast but extremely thin atmosphere, approaching the
size of the
sun, consisting of gas and debris thrown off the nucleus as it
orbits the
sun. The peak of this shedding of material is reached as the
comet
approaches the sun, and all the spacecraft's flybys will occur
when the
target comet is near this point in its solar orbit.
The scientific team will be particularly searching the coma for
evidence of
curious particles previously detected in interstellar clouds by
Jochen
Kissel, a comet researcher at the Max-Planck-Institute for
Extraterrestrial
Physics in Garching, Germany. Kissel made his discovery in data
sent back by
NASA's Stardust mission, which will reach comet Wild 2 in 2004.
The mission
is using the same dust analyzer as will be carried by the
CONTOUR. Said
Veverka, "The particles have a completely weird composition
and don't seem
to have minerals in them but seem to be made of chains of
carbon-hydrogen
and oxygen-nitrogen, like polymers. But there isn't any polymer
with that
kind of composition that we are normally familiar with."
There is an indication, said Veverka, that some particles might
have
weathered the massive meltdown of material when the sun and
planets were
formed from interstellar dust and clouds. "The question now
is, have any of
these particles been preserved in comets? We have to get close
enough to a
comet to find out." Although Encke has been much studied
from ground-based
observatories, little is known about its composition, which is
why the comet
experts gathered to exchange information on the object. Most
assumptions
about Encke, the researchers agreed, are drawn from data gathered
by the
European Space Agency's Giotto spacecraft, which visited comet
Halley in
1986. Much of what astronomers know about comets "comes from
the one object
we've come close to, comet Halley," noted Casey Lisse, an
astronomer at the
University of Maryland. However, the CONTOUR images from Encke
will be 25
times higher resolution than those from Halley.
Indeed, the most that the astronomers at the meeting could agree
on was that
Encke, some 30 million miles from Earth, is an extremely
elongated "icy dirt
ball" with a density, size, shape and rotation that defy
precise analysis.
Veverka wryly noted that the conflicting information about the
comet is such
that the mission will "not be dependent on any
prejudices."
And science team member Anita Cochran, a research scientist at
the McDonald
Observatory, the University of Texas, ruefully concluded that
"we started
off by saying we didn't know, and we just made up things from
there."
The complex journey of CONTOUR is shown in a computer simulation
video, made
for NASA by recent Cornell graduate Dan Maas, who previously
produced a
video for the 2003 Mars Rover mission. The new video can be seen
on the
CONTOUR web site at http://www.contour2002.org/
=============
(3) EXTREMELY CLOSE PLUTO APPULSE, POSSIBLE OCCULTATION
DISCOVERED
From Ron Baalke <baalke@zagami.jpl.nasa.gov>
FOR IMMEDIATE RELEASE
June 13, 2001
Contact:
Jeff Medkeff
Rockland Observatory (933)
medkeff@mindspring.com
520-378-0452
Bill Owen
Jet Propulsion Laboratory
wmo@wansor.jpl.nasa.gov
Extremely Close Pluto Appulse, Possible Occultation Discovered
A very close appulse of Pluto with GSC 5651-1553 will occur on 01
July 2002,
at approximately 23:00 UT.
The event was discovered by Arizona amateur astronomer and Sky
& Telescope
Contributing Editor Jeff Medkeff from his home in Sierra Vista.
He was using
SkyMap Pro 7.0 software to search for appulses of Pluto past
stars in order
to find favorable observing opportunities through the next 14
months.
After initially confirming the event with the Chapront and
Francou Planetary
Series (1996) planetary theory, and several other software
packages, he
alerted Jet Propulsion Laboratory scientist Bill Owen of the
event. The
event geometry is dependent upon three primary variables - the
uncertainty
in the position of the star, the uncertainty in the position of
Pluto, and
the theory used to describe Pluto's motion. Using the position of
this star
from the Tycho-II catalog, Owen's preliminary prediction suggests
that the
nominal event will have Pluto passing 1/3 arcsecond north of the
star, with
Charon 0.84 arcseconds south of Pluto - so that the star passes
between the
two. The uncertainties involved are sufficient that there is a
very slim
possibility that Pluto will occult the star.
According to Owen, recent astrometry of Pluto obtained
independently by Ron
Stone (USNO) and by Owen will be used by Myles Standish (JPL) to
update
Pluto's orbit. If the updated orbit does not rule out an event,
additional
astrometry will be pursued to further refine the predictions.
In any case, the event will provide an unusual opportunity for
amateur
observers to see Pluto exceptionally close to a field star.
==========
(4) THE BURSTING COMET LINEAR
From SpaceWeather.com
Space Weather News for June 16, 2001
http://www.spaceweather.com
BURSTING COMET: The crumbling comet C/2001 A2 (LINEAR), better
known as
"Comet LINEAR," brightened suddenly this week to
magnitude 3.3. Its fuzzy
head is easily visible to the unaided eye from dark-sky sites in
the
southern hemisphere, and the comet's tail is a beautiful sight
through
binoculars, say observers. Later this month the brightening
comet will also
make an appearance in northern skies.
SOLAR ACTIVITY: The sunspot number is up and solar activity is on
the rise
as well. A pair of coronal mass ejections that billowed
away from the Sun
on Friday could deliver glancing blows to Earth's magnetic field
this
weekend. Forecasters estimate a 15% chance of severe geomagnetic
storms at mid-latitudes by Sunday. Sky watchers should remain
alert for
auroras near local midnight.
For more information about viewing comet LINEAR and ongoing solar
activity
please visit SpaceWeather.com.
=============
(5) VENUS IS STANGE: WHAT CAUSED CELESTIAL BACKSPIN?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[ http://www.nature.com/nsu/010614/010614-10.html
]
Thursday, 14 June 2001
Celestial backspin inevitable
By PHILIP BALL
Venus is strange. It rotates from east to west. Every other
planet in the
Solar System turns west to east. It has been widely assumed that
this is
because a freak event up-ended Venus on its axis at some point in
the past.
Now two astronomers suggest that there are other ways our
neighbouring
planet could have gone into backspin.
Alexandre Correla and Jacques Laskar of Astronomie et Systèmes
Dynamiques in
Paris, France, calculate that Venus has only four states
available to it:
two that spin the normal way, and two retrograde. Under most
conditions,
retrograde motion is the most likely final state, they conclude
[1].
Laskar has previously shown that, thanks to myriad influences,
the tilted
rotation axes of all the inner planets -- Mercury, Venus, Earth
and Mars --
can wobble chaotically. This makes their behaviour highly
sensitive to tiny
effects and highly unpredictable. Tides sloshing Venus's thick
atmosphere
could thus have caused its rotation axis to flip. But only if the
initial
tilt was large.
But Venus need not have been in this special initial state to
acquire
retrograde rotation. Corella and Laskar have calculated how Venus
moves
around its orbit, allowing for tidal effects and for rubbing
between the
planet's rocky mantle and its molten core.
They find no unique answer. Because of the chaotic nature of the
motion, the
researchers had to run lots of computer simulations for different
initial
conditions, and look for the most common outcomes.
The four rotation states that they settle upon are likely to
apply to other
planets with dense atmospheres, such as the Earth. But for Venus,
the two
prograde states are much less stable than the two retrograde
states for a
wide range of initial conditions. So its unusual rotation may be
less a
matter of chance, and more an inevitability.
[1] Correla, A. C. M. & Laskar, J. The four final rotation
states of Venus.
Nature 411, 767-770 (2001).
© Macmillan Magazines Ltd 2001 - NATURE NEWS SERVICE
==========
(6) GEOLOGICALLY RECENT SHALLOW ICE AT MARS' EQUATOR?
From Andrew Yee <ayee@nova.astro.utoronto.ca>
News Services
University of Arizona
Tucson, Arizona
Contact Information:
Peter Lanagan, 520-621-1594, planagan@lpl.arizona.edu
Alfred McEwen, 520-621-4573, mcewen@pirl.lpl.arizona.edu
Laszlo Keszthelyi, 520-621-8284, lpk@lpl.arizona.edu
Jun 13, 2001
UA Scientists Find Evidence for Geologically Recent Shallow
Ground Ice at
Mars' Equator
By Lori Stiles
New high-resolution images from the Mars Orbiter Camera (MOC)
show evidence
of ground ice on Mars as recently as 10 million years ago.
More striking is that the signs of geologically recent ground ice
deposits
are near Mars' equator, where ice was probably no deeper than 5
meters (15
feet) below the surface, University of Arizona scientists say.
"If ground ice was present within 5 meters of the surface
only a few million
years ago, it is very likely to persist today within about the
upper 10
meters," said UA planetary sciences Professor Alfred S.
McEwen. "This is
especially interesting because it is an equatorial region of
Mars, more
accessible to exploration."
Peter D. Lanagan, McEwen and Laszlo P. Keszthelyi of the UA Lunar
and
Planetary Laboratory, and Thorvaldur Thordarson of the University
of Hawaii
have discovered clusters of tens to many hundreds of small
"rootless" cones
in MOC images of the Cerberus plains, Marte Valles, and Amazonis
Planitia
region near Mars' equator.
The martian cones are similar both in morphology and size to
rootless cones
in Iceland, features which form when surface lava interacts
explosively with
near-surface groundwater.
"The martian cones sit on pristine lava surfaces, and the
cones are
generally close to fluvial (water-carved) channels. The lavas do
not appear
to have been modified since they were emplaced, and some of the
channels
appear to be similarly pristine," Lanagan said.
Using crater counts and other geologic evidence seen in the
detailed new MOC
images, William K. Hartmann of the Planetary Science Institute in
Tucson and
others recently determined these lava flows to be as young as 10
million
years.
"We consider recent fluvial recharge to be the most likely
origin for the
shallow ground ice," the UA/Hawaii team conclude this week
in Geophysical
Research Letters. "If shallow ground ice in these regions
was present less
than 10 million years ago, deposits of shallow ground ice
probably persist
in the vicinity of the cone fields to the present day."
Rootless cones, or pseudocraters, do not form over volcanic
vents.
Thordarson concludes from years of fieldwork that in Iceland,
rootless cones
form where molten lava flows over marshy terrain. A crust forms
over the
lava flow, while molten lava continues to pump through tubes or
pathways
beneath the crust. As lava is shoved through the tubes, it mixes
with some
of the underlying water-rich sediment, and in the process of
mixing, the
water is heated by lava until it flashes to steam. When the steam
pressure
exceeds the pressure of the lava above it, there's a
"phreatomagmatic" -- or
groundwater and magma -- explosion. The result of several such
sustained
explosions is a cluster of cones associated not with any deep
fault or
fissure but with a network of lava tubes over the marshy area.
"We see many hundreds of similar cones in the Mars scape,
and they appear to
be associated either with low plains areas or with recent outflow
channels,"
Lanagan said. Water would flow to low areas, pond and percolate
in low
plains during the floods, recharging ground ice.
"If the terrestrial rootless cone analogy is extended to
Mars," he added,
"lava flows erupted over surfaces with ground ice --
probably at a depth of
less than 5 meters -- where they melted the ice to form a
water-rich slurry
which mixed with the tube-fed lavas. The process likely would
have resulted
in a series of phreatomagmatic explosions, which formed cones on
the top of
the chilled lava crust.
"The martian cones are close to outflow channels, so the
cones formed in
regions that were probably water- or ice-rich. Also, the martian
cones
generally are seen to sit on platy-ridged lavas similar to
Icelandic 'rubbly
pahoehoe' lava flows, where lavas delivered through tube networks
breaks the
hardened, chilled crust of the flow and move the resulting pieces
around
like a pulled-apart jigsaw puzzle. This suggests that the martian
cones
formed over lava flows fed by lava tubes, similar to rootless
cones in
Iceland."
Researchers debate whether the shallow ground ice that exploded
to create
the cones is relic ice leftover from the planet's formation,
recondensed
water vapor from the soil-atmosphere water vapor exchange, or
recharge from
surface flooding events.
"It is unlikely that relic ground ice has survived for 4
billion years in
equatorial regions of Mars," the UA/Hawaii team concludes.
The argument that equatorial ground ice could be recharged by an
exchange of
water vapor between the ground and the atmosphere -- as Arizona
State
University scientists have modeled -- is perhaps more plausible,
the team
wrote.
"However, because these cones appear to be near outflow
channels, we think
that the water the formed the cones is probably recharge from
floods,"
Lanagan said. Scientists studying Viking imagery in the late
1970s and 1980s
noted structures they interpreted to be rootless cones. Most of
these were
twice the size of the largest terrestrial cones, however, and it
was unclear
if some of these rested on actual volcanic surfaces.
The UA researchers looked at some of these areas again, this time
using
high-resolution MOC images, but still could not tell if the cones
sit on
volcanic surface because the terrain is either heavily mantled by
dust or
significantly eroded, Lanagan said.
"The structures observed by MOC are the first clearly
identified martian
cones having dimensions, morphologies, and geologic settings
similar to
terrestrial rootless cones," the team wrote in GRL.
***
Copies of the figures published in the GRL article,
"Rootless cones on Mars
indicating the presence of shallow equatorial ground ice in
recent times"
are available from the website
http://www.lpl.arizona.edu/~planagan/papers/grl_01a/
Addresses for jpgs and tiffs of the figures are as follows:
http://www.lpl.arizona.edu/~planagan/papers/grl_01a/fig1.jpg
(284k)
http://www.lpl.arizona.edu/~planagan/papers/grl_01.tif
(513k)
http://www.lpl.arizona.edu/~planagan/papers/grl_01a/fig2.jpg
(187k)
http://www.lpl.arizona.edu/papers/grl_01a/fig2.tif
(1.3M)
IMAGE CAPTION:
[For http://www.lpl.arizona.edu/~planagan/papers/grl_01a/fig2.jpg]
[Left] Cluster of cones north of the Cerberus plains on Mars, as
seen in an
image from the Mars Orbiter Camera. (PHOTO: NASA/JPL/Malin Space
Science)
[Right] Air photo of rootless cone field in Laki lava flow north
of Innryi
Eyrar, Iceland.
===========
(7) A COOL IDEA TO SAVE EARTH
From The New York Times, 17 June 2001
http://www.nytimes.com/2001/06/17/weekinreview/17RAMI.html
By ANTHONY RAMIREZ
AS the nation once again reaches for an iced tea to rub against
its
forehead, the chat turns inevitably, if listlessly, to global
warming, the
artificial raising of the planet's thermostat.
Ratify the Kyoto Protocol? Harms the American economy, says
President Bush.
Cut back on greenhouse emissions? Drives up electricity prices,
say
economists. Require smaller cars? Minivans carry my children to
school, say
the parents. Swelter, swelter, swelter.
Enter three scientists pushing a big, if long-term, idea: cool
down the
Earth by slowly moving it - the entire planet, that is - farther
away from
the Sun.
In a recent issue of the professional journal Astrophysics and
Space
Science, Don Korycansky, Greg Laughlin and Fred Adams playfully
propose
finding an asteroid about 60 miles long - about half the length
of Long
Island - to be used in a "gravitational sling shot."
A rocket could be strapped to the asteroid, they say, and the
asteroid
maneuvered into an immense orbit more than seven times wider than
the radius
of the solar system. The asteroid would then pass close enough to
Earth to
tug it gently away from the Sun. (One hitch, the authors
acknowledge, would
be a collision, which would "sterilize the biosphere most
effectively, at
least to the level of bacteria.")
While the solution may seem outsized, the three scientists are
actually
eyeing a larger-scale version of global warming. As the Sun burns
through
its hydrogen, it gets bigger and brighter, leading to hotter
temperatures on
Earth. In a billion years, the Sun will be 10 percent brighter,
killing off
many forms of life on Earth.
Moving the planet away from the Sun, in this view, is simply
shoving it away
from a red-hot stove.
It would be fitting if the idea occurred to Mr. Korycansky, the
paper's
principal author and a planetary scientist at the University of
California
at Santa Cruz, on a blistering summer day. But it was on a sunny
and mild
September day in 1999 that Mr. Korycansky chatted with Mr.
Laughlin, a
scientist at NASA's Ames Research Center, about the daunting
problem of the
Sun's lethal luminosity.
Earth-moving was Mr. Laughlin's idea, the asteroid was Mr.
Korycansky's,
while Mr. Adams, a University of Michigan physicist, was brought
in later to
figure out timing, which, as will be seen, is everything.
As they write in their paper, "the general problem of
long-term planetary
engineering is almost alarmingly feasible" using current
technologies.
After all, "gravitational slingshots" using Jupiter and
Saturn have already
been used to propel the Galileo and Cassini deep-space missions.
The
principle is a lot like a planetary square dance in which even
the tiniest
dancer can slightly deflect and accelerate a gargantuan partner,
and vice
versa, as they swing each other round and round.
An asteroid roughly 60 miles long passing within 10,000 miles of
Earth would
tug the planet into an orbit whose radius gets longer by about 30
miles with
each pass, or every 6,000 years. Of course, it would take a
long-lived
civilization to witness the feat - the equivalent of the ancient
Egyptians
firing a deep-space rocket with the expectation that their
descendants would
greet its return in the 21st century.
Nonetheless, Mr. Korycansky and his friends foresee at least one
million of
these orbits, slowly balancing out the Sun's increasing ferocity
and thus
preserving life on Earth.
BY the millionth pass, however, the Earth would have a 50 percent
larger
orbit.
"Of course, we'd then have to move Mars," Mr.
Korycansky said. Jupiter would
be affected, too, and so would Venus, but probably in ways too
small to
really matter to Earth. "The larger question is," he
said, "if you move a
planet, is it your responsibility to, you know, shepherd the
other planets?"
And the Earth, while rescued, would not escape consequences,
either. Every
time the asteroid passed, it would exert a tidal force 10 times
that of the
moon, leading to likely tsunamis, immense storms and other
disruptions. "We
would have to batten down the hatches," Mr. Korycansky said.
Don't even mention the seasons, say skeptical climate
researchers. A bigger
orbit means a longer year, affecting the all-important tilt of
Earth toward
the Sun.
"At a zero tilt, straight up and down, there would be no
seasons," said Dr.
Ronald J. Stouffer, who designs computer climate models at the
federal
Geophysical Fluid Dynamics Laboratory. "At a 90-degree tilt,
you have two
seasons, one that's all daylight all the time and the other
that's all
nighttime all the time."
Of course, the biggest complication of all is simply this:
Instead of
missing by a whisker, an ill-timed asteroid larger than Rhode
Island could
very well crash into the Earth. It would be the gravest
miscalculation
since, perhaps, a similar one many millions of years ago that
wiped out
ancient dinosaur astronomers.
Copyright 2001, The New York Times
============
(8) NASA AIMS TO MOVE EARTH
From The Observer, 10 June 2001
http://www.observer.co.uk/Print/0,3858,4201561,00.html
Nasa aims to move Earth
Scientists' answer to global warming: nudge the planet farther
from Sun
Robin McKie, science editor
Sunday June 10, 2001
The Observer
Scientists have found an unusual way to prevent our planet
overheating: move
it to a cooler spot.
All you have to do is hurtle a few comets at Earth, and its orbit
will be
altered. Our world will then be sent spinning into a safer,
colder part of
the solar system.
This startling idea of improving our interplanetary neighbourhood
is the
brainchild of a group of Nasa engineers and American astronomers
who say
their plan could add another six billion years to the useful
lifetime of our
planet - effectively doubling its working life.
'The technology is not at all far-fetched,' said Dr Greg
Laughlin, of the
Nasa Ames Research Center in California. 'It involves the same
techniques
that people now suggest could be used to deflect asteroids or
comets heading
towards Earth. We don't need raw power to move Earth, we just
require
delicacy of planning and manoeuvring.'
The plan put forward by Dr Laughlin, and his colleagues Don
Korycansky and
Fred Adams, involves carefully directing a comet or asteroid so
that it
sweeps close past our planet and transfers some of its
gravitational energy
to Earth.
'Earth's orbital speed would increase as a result and we would
move to a
higher orbit away from the Sun,' Laughlin said.
Engineers would then direct their comet so that it passed close
to Jupiter
or Saturn, where the reverse process would occur. It would pick
up energy
from one of these giant planets. Later its orbit would bring it
back to
Earth, and the process would be repeated.
In the short term, the plan provides an ideal solution to global
warming,
although the team was actually concerned with a more drastic
danger. The sun
is destined to heat up in about a billion years and so 'seriously
compromise' our biosphere - by frying us.
Hence the group's decision to try to save Earth. 'All you have to
do is
strap a chemical rocket to an asteroid or comet and fire it at
just the
right time,' added Laughlin. 'It is basic rocket science.'
The plan has one or two worrying aspects, however. For a start,
space
engineers would have to be very careful about how they directed
their
asteroid or comet towards Earth. The slightest miscalculation in
orbit could
fire it straight at Earth - with devastating consequences.
It is a point acknowledged by the group. 'The collision of a
100-kilometre
diameter object with the Earth at cosmic velocity would sterilise
the
biosphere most effectively, at least to the level of bacteria,'
they state
in a paper in Astrophysics and Space Science. 'The danger cannot
be
overemphasised.'
There is also the vexed question of the Moon. As the current
issue of
Scientific American points out, if Earth was pushed out of its
current
position it is 'most likely the Moon would be stripped away from
Earth,' it
states, radically upsetting out planet's climate.
These criticisms are accepted by the scientists. 'Our
investigation has
shown just how delicately Earth is poised within the solar
system,' Laughlin
admitted. 'Nevertheless, our work has practical implications. Our
calculations show that to get Earth to a safer, distant orbit, it
would have
to pass through unstable zones and would need careful nurturing
and nudging.
Any alien astronomers observing our solar system would know that
something
odd had occurred, and would realise an intelligent lifeform was
responsible.
'And the same goes for us. When we look at other solar systems,
and detect
planets around other suns - which we are now beginning to do - we
may see
that planet-moving has occurred. It will give us our first
evidence of the
handiwork of extraterrestrial beings.'
robin.mckie@observer.co.uk
Guardian Unlimited © Guardian Newspapers Limited 2001
=============
(9) MOVING HEAVEN AND EARTH: A COMMENT BY FRED SINGER
From S. Fred Singer <singer@sepp.org>
Dear Benny
There are a few "problems" with the scheme to move the
Earth to a more
distant orbit.
1. A single impulse would simply produce a more eccentric orbit
(unless
carefully applied at aphelion). Is that what we really want?
2. A close passage would also produce huge destructive
tides and change the
spin angular velocity of the Earth. I have previously calculated
some of
these effects in considering a capture origin of the Moon.
Best wished
S. Fred Singer, President
Science & Environmental Policy Project
http://www.sepp.org
===========
(10) THE K/T MASS EXTINCTION IN THE MARINE REALM: YEAR 2000
ASSESSMENT
From http://www.elsevier.nl/gej-ng/10/37/40/42/30/32/abstract.html
Planetary and Space Science, Vol. 49 (8) (2001) pp. 817-830
© 2001 Elsevier Science Ltd. All rights reserved.
PII: S0032-0633(01)00032-0
The end-cretaceous mass extinction in the marine realm: year 2000
assessment
Gerta Keller * gkeller@princeton.edu
Department of Geosciences, Guyot Hall, Princeton University,
Princeton NJ
08544-1003 USA
Received 11 September 2000; accepted 29 November 2000
Abstract
The current database indicates that the terminal decline and
extinction, or
near extinction, of many groups commonly attributed to an
asteroid or comet
impact at the Cretaceous-Tertiary (K-T) boundary (e.g.,
ammonites, bivalves,
planktic foraminifera) began during the last 500k.y. of the
Maastrichtian.
By the time of the K-T boundary, extinction-prone tropical and
subtropical
marine faunas and floras were almost gone, or had severely
reduced species
populations struggling to survive. The K-T boundary kill-effect
was largely
restricted to these struggling tropical and subtropical
populations that
accounted for 2/3 of the species among planktic foraminifera, but
less than
10% of the total foraminiferal population. No significant
extinctions
occurred among ecological generalists that dominated across
latitudes. No
single kill mechanism can account for this mass extinction
pattern. The last
500k.y. of the Maastrichtian were characterized by a series of
rapid and
extreme climate changes characterized by 3-4°C warming between
65.4 and
65.2Ma, major volcanic activity between 65.4 and 65.2Ma, a
spherule-producing event between 65.3 and 65.2Ma, and an impact
at the K-T
boundary (65.0Ma). All of these events caused major environmental
perturbations and biotic stresses that resulted in severe
reductions in
species populations and extinctions that culminated at the K-T
boundary. The
mass extinction pattern, and the parallel environmental changes
during the
last 500k.y. of the Maastrichtian, suggest that both long-term
(climate,
sea-level) and short-term (impact, volcanism) events contributed
to the K-T
boundary mass extinction.
*Tel.: 1-609-258-4117; fax: 1-609-258-1671
Full text supplied by [ScienceDirect]
© Copyright 2001, Elsevier Science, All rights reserved.
===========
(11) SNOWBALL EARTH
From Andrew Yee <ayee@nova.astro.utoronto.ca>
From the Boston Globe, 12 June 2001
[ http://www.boston.com/dailyglobe2/163/science/Snowball_EarthP.shtml
]
Tuesday, June 12, 2001
Snowball Earth
Science grapples with a puzzling new theory: the extreme ice age
By David L. Chandler, Boston Globe Staff, chandler@globe.com
Even the scientists who first thought up the idea didn't think it
was
possible: That the entire Earth could have frozen over and been
encased in a
solid cover of snow and ice, perhaps for millions of years.
When the idea first showed up in a computerized climate model, it
seemed out
of the question. If Earth was frozen solid, how could any life
have
survived? And how could an ice-covered planet ever have thawed
again?
But a rising tide of evidence over the last decade has turned
what at first
seemed like a crazy concept into a mainstream theory. In fact, it
may be the
only way to explain a whole series of seeming paradoxes and
puzzles about
this planet's geology and climate.
At a recent meeting in Boston of the American Geophysical Union,
a long
session on the so-called "snowball Earth" theory was
concerned not so much
with whether it happened -- the evidence now indicates it
happened at least
twice, and perhaps as many as five times -- but with the details
of how, why
and when the planet was suddenly plunged into the deep freeze,
and how it
just as suddenly thawed out like a Thanksgiving turkey.
While the "snowball" episodes may have lasted 10
million years or more, the
actual freezing and thawing probably happened in just a matter of
decades --
perhaps providing an important clue into just how unstable and
vulnerable
the planet's climate system is. And, some scientists now suggest,
the cycle
of freezing and thawing may have been crucial in making all
higher forms of
life possible, including the humans who are now piecing together
this
ancient puzzle.
"Something about the snowball causes life to diversify and
change," said
Joseph Kirschvink, a geobiologist at the California Institute of
Technology
who first coined the term "snowball Earth" in a 1992
paper in Science.
The concept of snowball Earth first struck Kirschvink during a
geological
expedition to Australia in the late 1980s. There, he and a group
of other
geologists and biologists specializing in reconstructing the
ancient
environment were struck by abundant evidence of extensive
glaciers, embedded
in the layers of ancient rock. But there was a big problem: Other
evidence
clearly showed that, at the time of these deposits some 700
million years
ago, Australia lay squarely on the equator.
How could sea-level glaciers possibly have existed under the
tropical sun?
The implication was clear. If glaciers reached all the way to the
sea even
in the tropics, the whole planet must have been frozen at the
time.
And, it turned out, the theoretical explanation had already been
proposed,
back in the 1960s, from a computer climate model. In a kind of
reverse-greenhouse effect, a sudden depletion of methane in the
atmosphere
could cause a dramatic drop in temperatures, leading to an
advance of
glaciers similar to the familiar ice ages of more recent times.
But there
comes a crucial turning point: If the ice reaches as far south as
30 degrees
latitude -- about the level of northern Florida -- then it
triggers an
unstoppable "runaway" freezing cycle.
That's because ice and snow reflect most of the sunlight that
falls on them,
radiating away the heat. Darker open water or soil, by contrast,
absorbs the
sun's heat. So, as darker surface gives way to white snow and
ice, less and
less sunlight can be trapped to warm the planet, and the Earth
cools faster
and faster, producing more ice, which cools it even more.
The result: Within a span of a few decades, the Earth could
freeze over. Any
remaining simple, single-celled life would be limited to
surviving in
deep-ocean thermal vents, ponds melted on the land by volcanic
heat, or
patches of ocean where the ice was thin enough for sunlight to
filter
through and support photosynthesis.
The big puzzle, at first, was how such a snowball could ever
reverse itself
and thaw out again. That was Kirschvink's big breakthrough. He
figured out
that even on a frozen-solid Earth, volcanos would continue to
erupt,
belching the greenhouse gas carbon dioxide into the air. Over
time -- about
10 million years -- at today's rate of volcanism, enough would
build up to
create a "super-greenhouse" effect, strong enough to
melt the whole planet
-- again, in a span of just a few decades, once the process
started.
"I didn't think it was possible" when Kirschvink first
proposed the idea,
said James Kasting of Pennsylvania State University, who is now
one of the
concept's strongest advocates. "I thought it would have
extinguished all
life. Now, I see there are ways out."
And, Kasting said, it is now clear that the theory can explain
many
geological features that had been major enigmas for scientists.
One of the
most significant ones concerns deep deposits of carbonate rock
that appear
in the sedimentary layers immediately following those that show
signs of
tropical glaciers.
These "carbonate capstones" can be dozens of feet -- in
some places,
hundreds of feet -- thick, and are found all over the globe from
the era
immediately following the hypothesized snowball episodes.
Geologists had
been at a loss to explain them.
But, in 1998, Paul Hoffman and Daniel Schrag, two geologists at
Harvard
University, came up with the explanation: A sudden, dramatic
weathering of
exposed rock immediately after the planet thawed out again,
flushing
enormous quantities of carbonate into the oceans.
"They're predicted" by the snowball Earth theory,
Kasting said of the
carbonate capstones. "They are the smoking gun" that
points directly to the
truth of the theory.
And it is largely because of that smoking gun, he said, that the
whole
theory has gained acceptance: "When it was first proposed,
there was a lot
of resistance. Now, it's become mainstream."
Hoffman himself is more guarded: "The community is really
polarized," he
said last week. "There are a lot of people sitting on the
fence, because
it's really such a radical idea." But, he said, while
Kirschvink's original
theory "was kind of ignored," it is really since he and
Schrag published
their paper in 1998 "that the real attention and intense
interest has
developed" in the idea.
Now, the focus has shifted to understanding exactly how the
process worked,
and how it affected the rise and diversification of life as we
know it.
Kirschvink, who presented his latest analysis at the recent
geophysics
meeting, said he thinks he now has the answer to what the
"something" is
that caused life to burgeon just after the frozen episodes: A
huge increase
in oxygen immediately following the snowball's big thaw.
"Snowballs produce massive oxygen spikes," he said,
"perhaps stimulating
major evolutionary innovations." And that may include, he
suggested, one of
the most crucial innovations of all: The development of
multicellular life,
after more than 3 billion years when Earth was populated only by
single-celled organisms.
In Kirschvink's view, the question is not so much why complex
animals surged
into existence when they did -- about 550 million years ago,
right after the
last snowball episode -- but why that didn't happen much sooner.
"There's
nothing in the history of this planet that would have prevented
animals from
radiating a billion years ago, or 2 billion," he said in an
interview last
week.
"Something was holding them back," he said. "I
think it was oxygen."
The reason for the sudden pulse of oxygen involves the action of
billions of
tiny single-celled organisms called cyanobacteria, also known as
blue-green
algae.
It turns out that the big thaw would have produced giant storms
and intense
acid rain, producing a surge of intense weathering of the
freshly-exposed
rocks and washing vast amounts of carbon, phosphorous, iron and
other
essential nutrients into the oceans. "Everything you need
for cyanobacteria
to go haywire is there," Kirschvink said -- very similar to
the growth media
used to grow colonies of bacteria in the lab. "I think
they'd be very
happy."
The result, he suggested, would have been "a massive
cyanobacteria bloom --
I call it green Earth. If you have a whole planet of growth
medium, and
nothing to stop it, the expected result is a massive oxygen
spike."
And there is abundant geological evidence that exactly such a
spike of
oxygen did indeed take place, he said. For example, all this
oxygen would be
expected to mix chemically with manganese and iron, forming
minerals that
would then drop to the sea floor. And indeed, in formations that
arose just after the snowball episode, massive layers of
manganese and iron
ores are found in many places.
In fact, he said, the world's largest commercial deposit of
manganese,
source of 80 percent of global manganese production, occurs in
just such a
formation in South Africa -- called Hotazel, in reference to the
super-greenhouse heating of the planet at that time.
But perhaps the biggest lesson from the whole snowball Earth
concept is just
how vulnerable the Earth's climate system is to dramatic, rapid
changes and
unanticipated feedback effects.
Snowball Earth "is an extreme example of an instability of
the climate
system," Hoffman said. "As a geologist, the remarkable
thing about the last
10,000 years is how remarkably stable the climate has been."
© Copyright 2001 Globe Newspaper Company.
============================
* LETTERS TO THE MODERATOR *
============================
(12) RE: CCNet ESSAY: ESTIMATED FLUX OF ROCKS BEARING VIABLE
LIFEFORMS
EXCHNAGED BETWEEN EARTH
From Oliver Morton <abq72@pop.dial.pipex.com>
Michael Paine wrote:
>About one fifth of the ejected rocks eventually return to
planet
from which
>they were launched. Davies (1998a) points out the possibility
that
microbes
>in these rocks might reseed a planet after its biosphere had
been
sterilised
>by huge impacts. This is a possible mechanism for life
becoming
>re-established on Earth after the Late Heavy Bombardmant
(Bortman
2000- note
>that Bortman does not consider this mechanism in his report).
It may be worth noting that this possibility suggests a
pre-adaptation for
transpermia, in that it gives survival value to the ability to
hang out in
rocks thrown into space. I think Norm
Sleep and Kevin Zahnle talk about this in "Refugia from
asteroid impacts on
early Mars and the early earth" (JGR 103, 28529-28544,
1998); if they don't,
then I guess I must have thought it up after reading their paper.
useful essay -- thanks a lot
o
Oliver
Morton
The Apse
142A Greenwich High Road
London SE10 8NN
Tel: 44 20 8293 7171
abq72@dial.pipex.com
============
(13) "VIRTUALLY IMPOSSIBLE FOR ANYTHING TO BE EJECTED FROM
THE SURFACE OF A
PLANET BY AN IMPACT "
From John Michael Williams <jwill@AstraGate.net>
Hello Larry.
A friend sent me a copy of an Email link you sent him.
CCNet ESSSAY: ESTIMATED FLUX OF ROCKS BEARING VIABLE
LIFEFORMS EXCHANGED
BETWEEN EARTH AND MARS
by Michael Paine, The Planetary Society Australian
Volunteers
<mpaine@tpgi.com.au>
http://abob.libs.uga.edu/bobk/ccc/ce061201.html
The problem with this idea, is that proponents of it have not
attempted to
verify it even against elementary calculations that an amateur
astronomer
might be able to carry out.
It is virtually impossible for anything to be ejected by an
impact from the
surface of Mars or any planet with a similar or greater escape
speed.
The short reason is that nothing can be accelerated in solid form
by a force
propagating across it faster than 2/3 the speed of sound in it.
In fact, as
shown by elementary methods in a paper at
http://publish.aps.org/eprint/gateway/eplist/aps1999jun25_002,
nothing could
have been ejected from Mars intact unless the speed of sound in
it was ~7.5
km/s. The speed of sound in a fast rock such as granite is only 6
km/s, and
the speed of sound in a living or dormant cell would be below 2
km/s--probably closer to that in water (1.5 km/s?). Speeds in dry
wood range
up to about 4 km/s. The Mars escape speed is about 5 km/s.
It is worrisome that this idea is being promoted as
"scholarly": Two of the
persons whose work is often cited in support of it, Melosh and
Ahrens,
refuse to comment on the paper above, even in the context of an
ongoing
meeting on a related subject. A "scholar" with an
imaginative idea should be
willing to entertain that it might be wrong.
--
John
jwill@AstraGate.net
John Michael Williams
===================
(14) SHOCK, HORROR: VIRTUALLY IMPOSSIBLE MARS METEORITE FOUND IN
OMAN
From Space.com, 17 June 2001
http://www.space.com/scienceastronomy/solarsystem/oman_meteorite_wg_010615.html
By Alexander G. Higgins
Associated Press
GENEVA (AP) -- A fist-sized meteorite, one of only 18 rocks on
Earth known
to have come from Mars, has been found by Swiss scientists in the
Oman
desert -- a prize discovery that could help determine if the
planet ever
sustained life.
Scientists at the University of Bern announced the find Friday
and said they
are just beginning to examine the meteorite. Most of the other 17
Martian
rocks have been snapped up by collectors, they said, so few are
fully
available for study.
"I suspected from the beginning that it was from Mars,''
said Marc Hauser, a
geologist who found the gray, ridged specimen during a collecting
excursion
in January. "The color was different and, above all, it
wasn't magnetic.''
Initial conclusions could take several months.
Unusually large pockets inside the 223.3 gram (half-pound) rock
could
provide evidence about life that is far more conclusive than
American
suggestions about possible fossils on an earlier meteorite found
in
Antarctica, Hauser told The Associated Press.
The new meteorite was named Sayh al Uhaymir 094 after the region
of desert
where the team found it and more than 180 other meteorites. The
team, in a
statement, said they were certain it would contribute to rapidly
growing
knowledge of the planet.
Interest increased in 1996 after a Martian meteorite found near
the South
Pole, known as Allen Hills 84001, showed possible remnants of
life. But such
arguments "are hardly taken as solid evidence today,"
the research team
said.
Most earlier meteorites from Mars were found in the Antarctic
before
scientists turned their attention to deserts in recent years.
Hauser said X-rays of the new rock had shown a surprising number
of hollow
pockets inside that might contain gases or atmosphere. That could
offer
clues about both the meteorite's history and Mars itself.
The pockets have "a much greater potential" than the
rest of the rock for
containing evidence of life on Mars, Hauser said.
Most of the 180 meteorites found by the team were magnetic and
looked
distinctive, but the Martian rock looked more like rocks from
Earth and was
difficult for the team to recognize as a meteorite. The other
meteorites
also contained no minerals.
Hauser said the team believes the Martian meteorite is part of
another one
found earlier in the same area.
That first rock is in unknown private hands, as are most Martian
meteorites
because collectors are willing to pay $1,000 a gram for such
treasures. But
the team was able to obtain a small fragment of it for testing,
Hauser said,
and its makeup is practically identical.
The team said they and other scientists had determined their
meteorite is
from Mars by the nature of its minerals, measurements of its
oxygen isotopes
and its overall composition. They conducted analyses on both the
entire rock
and tiny fragments of it.
They said the rock had been formed from molten lava, similar to
volcanic
rocks on Earth.
Mars is the most Earth-like of all the solar system's planets,
and evidence
suggests both planets developed similarly during their first
billion years
-- the period when life first appeared on Earth.
The team said recent discoveries about life on Earth in extreme
environments
-- such as in very hot ocean springs or within porous rocks deep
inside the
planet's surface, support the theory that early Mars could have
had
environments suitable for life.
The rare Martian meteorites could be the only physical evidence
available to
scientists for at least 10 years, when a U.S. space probe might
bring back
500 grams (1.1 pounds) of Martian samples "at very high
costs."
Rocks from Mars start their journey toward Earth when a meteorite
from
elsewhere slams into the Martian surface, scattering rocks into
space at
high speed. They eventually make their way to Earth, sometimes
after
millions of years.
Copyright 2001, Space.com
===========
(15) AND FINALLY: YOU HAVE E-MAIL ... FROM SPACE
From Discovery News, 18 June 2001
http://dsc.discovery.com/news/briefs/20010611/spacenet.html
By Irene Brown
June 14 - Internet pioneers are laying the groundwork to expand
the Web into
space, with testing planned for later this year.
The Interplanetary Internet would link the Web with new hubs on
spaceships,
satellites, planets, the moon, robotic probes and other
extraterrestrial
outposts.
"The best way to envision the fundamental architecture of
the Interplanetary
Internet is to picture a network of Internets," a research
group headed by
Internet pioneer Vinton Cerf wrote in a proposal to the Internet
Engineering
Task Force, which sets standards for the Internet.
Cerf, creator of the TCP/IP Internet communications protocol, is
working
with representatives from NASA, the Defense Advanced Research
Projects
Agency, The Mitre Corp., Global Science and Technology and SPARTA
in
developing plans for a next-generation Internet.
The new protocol is expected to be tested on the Space Technology
Research
Vehicle, a British-led project to test new space technologies.
The satellite
is scheduled to be launched later this year.
And a live test is under consideration for a NASA mission to Mars
in 2003.
While technical and security concerns are paramount, the
Interplanetary
Internet research team also wants to be sure the new system will
support
commercial endeavors, such as communication services, asteroid
mining, space
tourism and manufacturing.
"While such developments may still lie decades in the
future, the potential
investment and benefits can be appreciated as we contemplate the
explosion
of new markets associated with the commercialization of the
Internet that
began just 10 years ago. We will therefore architect the
Interplanetary
Internet in anticipation of possibly rapid
commercialization," Cerf and his
team wrote.
The team envisions an email like approach to interplanetary
communications
to account for time delays and hubs that may not always be within
range of
each other.
"Sometimes a planet will be between the source and the
destination," said
Scott Burleigh of NASA's Jet Propulsion Laboratory, who is a
member of the
Interplanetary Internet team.
Ground tests may also be part of a simulated Mars mission taking
place in
the Canadian Arctic this summer, said Marc Boucher, with the Mars
Society.
Copyright © 2001 Discovery Communications Inc.
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