PLEASE NOTE:
*
CCNet, 046/2000 - 7 April 2000
------------------------------
"But is it possible that tiny
creatures from another world
somehow hitched a ride on a comet,
crash-landed on Earth, then
began to multiply and conquer the
planet? The idea is known as
panspermia - the theory that
microscopic life was delivered to
Earth billions of years ago from
outer space. First proposed in
1865, panspermia has gained
widespread support in recent years
with the discovery of organisms
that thrive in extreme
environments like those found
elsewhere in space - boiling or
freezing temperatures, extreme
acidity and even heavy doses of
radiation."
-- Mark Shwartz, Standford University
(1) SCIENTISTS PONDER EXTRATERRESTRIAL ORIGIN OF LIFE
Stanford News Service <stanford.report@forsythe.stanford.edu>
(2) EROS' AGING CRATERS
Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
(3) AH, FOLLOW-UP OBSERVATIONS INVALIDATE PROTOPLANET CLAIMS
NASANews@hq.nasa.gov
(4) DETECTING SUNSPOTS ON THE FAR SIDE OF THE SUN
PHYSICS NEWS UPDATE <physnews@aip.org>
(5) ASTROD ORBIT SIMULATION
D.W. Chiou*) & W.T. Ni, NATL TSING HUA
UNIVERSITY
(6) ANALYTICAL SOLUTION TO THE KOZAI RESONANCE
H. Kinoshita*) & H. Nakai, NATIONAL
ASTRONOMICAL OBSERVATORY
(7) GEOLOGICAL UNITS ON VENUS: EVIDENCE FOR GLOBAL CORRELATIONS
A.T. Basilevsky*) & J.W. Head,
RUSSIAN ACAD SCI
(8) AND FINALLY: A TIMELY CLARIFICATION
Leon Jaroff <NEONLEO@aol.com>
=========
(1) SCIENTISTS PONDER EXTRATERRESTRIAL ORIGIN OF LIFE
From Stanford News Service <stanford.report@forsythe.stanford.edu>
04/06/00
CONTACT: Mark Shwartz, News Service (650) 723-9296;
e-mail mshwartz@stanford.edu
For NASA illustration: http://nai.arc.nasa.gov/press.cfm?page=gallery
Scientists ponder the extraterrestrial origin of life
The question of whether life exists elsewhere in the universe
left the
realm of science fiction this week, as NASA hosted the galaxy`s
first
Astrobiology Science Conference.
The event was held April 3-5 at the NASA Ames Research Center in
Mountain View, Calif.
The conference brought together researchers from Stanford and
dozens of
other institutions to discuss new developments in the burgeoning
field
of astrobiology, which NASA defines as ``the study of the origin,
evolution, distribution and destiny of life in the universe.``
While several authors submitted papers on the search for
extraterrestrial intelligence, most focused on the question of
whether
simpler life forms, such as bacteria, exist elsewhere in our
solar
system or in other galaxies.
Christopher F. Chyba, associate professor (research) of
geological and
environmental sciences, co-authored a study showing that
life-giving
organic molecules could have arrived on Earth and other planets
aboard
fast-moving comets.
"Life as we know it requires organic compounds, liquid water
and a
source of energy," wrote Chyba and Elisabetta Pierazzo of
the
University of Arizona.
"Few places in the solar system appear to satisfy these
requirements,"
they noted, except Earth, Mars and Jupiter`s moon, Europa.
Previous studies showed that comets contain organic compounds
such as
amino acids, the building blocks of proteins.
Using computer simulations, Chyba and Pierazzo concluded that
certain
amino acids could have survived "large cometary
impacts" billions of
years ago, becoming part of a primordial soup that eventually
gave rise
to single-celled organisms on Earth - and perhaps on Mars and
Europa.
But is it possible that tiny creatures from another world somehow
hitched a ride on a comet, crash-landed on Earth, then began to
multiply and conquer the planet?
The idea is known as panspermia - the theory that microscopic
life was
delivered to Earth billions of years ago from outer space.
First proposed in 1865, panspermia has gained widespread support
in
recent years with the discovery of organisms that thrive in
extreme
environments like those found elsewhere in space - boiling or
freezing
temperatures, extreme acidity and even heavy doses of radiation.
One NASA Ames researcher pointed to recent experiments with a
species
of worm called C. elegans that is only a millimeter long.
Miniature
worms were placed in a centrifuge then spun at 10 Gs, or 10 times
the
gravitational force felt on Earth.
The little creatures survived four days of spinning - no surprise
to
Stuart Kim, associate professor of developmental biology at
Stanford.
"These worms will live at 100,000 Gs," said Kim, who is
conducting
additional studies with NASA Ames to see if extreme gravitational
forces affect a worm`s ability to regulate cell growth,
metabolism and
other genetic functions.
To find out how quickly invasive species adapt on Earth,
conference
organizers invited Stanford biologist Harold A. Mooney, the Paul
S.
Achilles Professor of Environmental Biology.
Mooney is an authority on how natural ecosystems are transformed
by the
introduction of exotic plants and animals.
"Our world, our planet, is now one world," he told the
audience,
noting that the oceanic walls separating the continents were
breached
long ago by Columbus and subsequent explorers.
Mooney said that improvements in global transportation have
caused even
more ecological disruption, pointing out that, between 1961 and
1995, a
new marine species was inadvertently introduced into San
Francisco Bay
every week in the ballast water of cargo ships from Asia and
other
continents.
"That`s just a blip in geologic time," Mooney noted,
adding that even
Earth-bound ecologists "can`t predict which organisms will
become
successful invaders."
Stanford geophysicist Norman H. Sleep presented a paper arguing
that
the Earth`s oceans contain just the right amount of water to
sustain
oxygen-breathing organisms.
According to Sleep, if the oceans were twice as deep as they are
today,
the continents would be submerged, exposing only a small amount
of
granite to the atmosphere.
When granite weathers, it turns into clay, which then absorbs
excess
carbon from the air as it becomes shale.
Without clay, too much carbon would remain in the atmosphere,
stealing
oxygen molecules to form carbon dioxide gas, which is toxic to
most
animals.
On the other hand, if the oceans were half as deep, atmospheric
oxygen
would be soaked up by iron-rich basaltic rocks that are now
submerged
under seawater. "Getting just the right amount of
water," Sleep
concluded, "is a hurdle in having complex life forms on a
planet."
==========
(2) EROS' AGING CRATERS
From Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
NEAR image of the day for 2000 April 5
http://near.jhuapl.edu/iod/20000405/index.html
Eros' many craters have a range of ages dating back to the
last time
the asteroid's surface was "wiped clean" by
geologic processes. This
NEAR Shoemaker image of the
tip of the asteroid, taken March 6,
2000, from a range of 201 kilometers (125 miles), shows craters
with
a variety of shapes and sizes. When
small craters first form,
they typically have sharp rims and
round floors. As they
age, progressively smaller craters are superimposed,
rounding the
rims and pitting the walls and
floors until the original
underlying crater becomes almost unrecognizable.
----------------------------------------------
Built and managed by The Johns Hopkins University Applied Physics
Laboratory, Laurel, Maryland, NEAR-Shoemaker was the first
spacecraft
launched in NASA's Discovery Program of low-cost, small-scale
planetary
missions. See the NEAR web site for more details
(http://near.jhuapl.edu) .
==============
(3) AH, FOLLOW-UP OBSERVATIONS INVALIDATE PROTOPLANET CLAIMS
From NASANews@hq.nasa.gov
Donald Savage
Headquarters, Washington,
DC
April 6, 2000
(Phone: 202/358-1547)
Nancy Neal
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/286-0039)
Ray Villard
Space Telescope Science Institute, Baltimore, MD
(Phone: 410/338-4514)
RELEASE: 00-58
SUSPECTED PROTOPLANET MAY REALLY BE A DISTANT STAR
Follow-up observations of an unusual
object initially
suspected to be the first directly detected planet outside our
solar system have shown that the object is too hot to be a
planet.
Astronomers now believe it is more
likely that the strange
object is a background star whose light has been dimmed and
reddened by interstellar dust, giving the illusion that it is in
the vicinity of the double star system in which it was initially
believed to have been a planet.
NASA's Hubble Space Telescope
photographed the mysterious
object, called TMR-1C, in 1997. The picture shows a bright
dot at
the end of a long streamer of reflective dust stretching 135
billion miles (225 billion kilometers) back to the binary star
located 450 light-years away in the constellation Taurus the
bull.
A light year is about 6 trillion miles.
In 1998, astronomer Susan Terebey of the
Extrasolar Research
Corp., Pasadena, CA, reported her observation at a scientific
meeting as a possible young and hot "protoplanet"
several times
the mass of Jupiter. Because of its potential importance
and the
compelling nature of the image, NASA also released the picture to
the public with the caution that future observations would be
critical in verifying whether or not this object actually is a
planet.
Tereby initially proposed that the
object had been ejected
from a double star system via a "slingshot" effect
(interaction
with one of the stars or another giant planet). Since then
she has conducted follow-up observations with the 10-meter Keck
telescope in Mauna Kea, HI, to test her hypothesis.
Now, in results to be published in the
May Astronomical
Journal, Tereby reports, "The new data do not lend weight to
the
protoplanet interpretation and the results remain consistent with
the explanation that TMR-1C may be a background star.
Although
the Hubble image is striking, there is the alternate possibility
that TMR-1C is an unrelated background star, seen, by chance,
projected close to the young star system. Finding a clearer
answer is difficult for an object as faint as TMR-1C."
To better understand the nature of this
faint object, Tereby
used the Keck telescope to measure TMR-1C's temperature by
dissecting its light through spectroscopy. Much like the
way a
prism disperses sunlight to make a colorful rainbow, a spectrum
breaks apart the light from the observed object. The relative
amounts of red and blue light help tell the object's temperature.
Tereby and colleagues then constructed
models of dust-
obscured objects to compare with the spectrum of TMR-1C and found
a corresponding temperature of greater than 4400 degrees
Fahrenheit (2700 degrees Kelvin) for TMR-1C. This is hotter than
the predicted temperatures of young giant planets.
"However the models are not yet
reliable at such young ages,
so this test by itself is not conclusive," Tereby cautions.
"The
idea remains alive and well that there may be runaway planets and
brown dwarfs (small stars that failed to sustain nuclear fusion)
which formed via ejection from multiple star systems. Theoretical
models by several groups support this idea, and new searches --
including ours -- are finding many new candidates in star-forming
regions. However at this time there is no strong evidence that
TMR-1C itself is a protoplanet."
EDITOR'S NOTE: The Hubble image of TMR-1C and the initial
press
release (from May 28, 1998) are available at:
http://oposite.stsci.edu/pubinfo/pr/1998/19/
=========
(4) DETECTING SUNSPOTS ON THE FAR SIDE OF THE SUN
From PHYSICS NEWS UPDATE <physnews@aip.org>
SUNSPOTS ON THE FAR SIDE OF THE SUN can be detected through
helioseismic holography, a process in which the sound waves that
rumble
through the body of the sun are slightly distorted when they
reflect
from the magnetically active regions around sunspots. In
March of
1998, data from the orbiting Solar Heliospheric Observatory
(SOHO) were
processed with an algorithm that deduces the locations of those
out-of-sight sunspots. Charles Lindsey and Douglas Braun of the
Solar
Physics Research Corp. report that their calculations of presumed
sunspot positions on the far side of the sun correlated well with
actual spots that later swung into view (revolving along with the
sun
on its 27-day rotation). The researchers expect that
eventually this
method will be able to give valuable advance warnings of the type
of
space storms that arise from the solar flares and coronal mass
ejections associated with the active regions on the sun's
surface.
Predicting "space weather" in the Earth-sun environment
is important
since astronauts' lives, the survival of satellites, and the
stable
operation of terrestrial power grids are tied to the
particles and
radiation that comes rushing at us from the sun. (Lindsey
and Braun,
Science, 10 March 2000.)
=========
(5) ASTROD ORBIT SIMULATION
D.W. Chiou*) & W.T. Ni: ASTROD orbit simulation and accuracy
of
relativistic parameter determination. ADVANCES IN SPACE RESEARCH,
2000, Vol.25, No.6, pp.1259-1262
*) NATL TSING HUA UNIVERSITY,DEPT PHYS,CTR GRAVITAT &
COSMOL,HSINCHU
30043,TAIWAN
In this paper, we present our ASTROD orbit simulation with
uncertainty distributions to investigate the accuracy for
determination of relativistic parameters and other relevant
parameters. ASTROD mission concept is to use drag-free spacecraft
in
solar orbits together with a constellation of Earth orbiting
satellites to provide high-precision measurement of relativistic
effects, better determination of the orbits of major asteroids,
improvement in the measurement of (G) over dot, measurement of
solar
angular momentum via Lense-Thirring effect and the detection of
low-frequency gravitational waves and salar oscillations in a
single
mission. In our orbit simulation, we first establish a
deterministic
model and then extend it to a,stochastic model. With this
stochastic
model, the accuracy of parameter determination for beta, gamma
and
J(2) is obtained and discussed. (C) 2000 COSPAR. Published by
Elsevier Science Ltd.
=========
(6) ANALYTICAL SOLUTION TO THE KOZAI RESONANCE
H. Kinoshita*) & H. Nakai: Analytical solution of the Kozai
resonance
and its application. CELESTIAL MECHANICS & DYNAMICAL
ASTRONOMY, 1999,
Vol.75, No.2, pp.125-147
*) NATIONAL ASTRONOMICAL OBSERVATORY,2-21-1
OSAWA,MITAKA,TOKYO,JAPAN
When Kozai (1962) studied the secular resonance of asteroids, he
found the so-called Kozai resonance and expressed the analytical
solution with the use of Weierstrass p. Here we discuss the case
where the disturber is outside a disturbed body and give the
analytical solution of the eccentricity, the inclination and the
argument of pericenter with the use of the Jacobi elliptic
functions,
which are more familiar than the Weierstrass p. Then we derive
the
Fourier expansion of the longitude of node and the mean anomaly.
The
analytical expressions obtained here can be used for any value of
the
eccentricity and the inclination. Finally we applied these
analytical
expressions to several dynamical systems - Nereid, that is a
highly
eccentric satellite of Neptune, and newly discovered retrograde
satellites of Uranus. Copyright 2000, Institute for Scientific
Information Inc.
=================
(7) GEOLOGICAL UNITS ON VENUS: EVIDENCE FOR GLOBAL CORRELATIONS
A.T. Basilevsky*) & J.W. Head: Geologic units on Venus:
evidence for
their global correlation. PLANETARY AND SPACE SCIENCE, 2000,
Vol.48,
No.1, pp.75-111
*) RUSSIAN ACAD SCI,VI VERNADSKY INST GEOCHEM & ANALYT
CHEM,MOSCOW,RUSSIA
Detailed geologic mapping of approximately 30% of the surface of
Venus
has revealed a stratigraphic sequence that appears to be repeated
in
widely separated areas on the planet. This sequence shows a
transition
from oldest highly deformed terrain units, the tessera, to a
series of
widespread volcanic plains units, each with recognizable
morphologic
characteristics and interpreted eruption style, and finally to
individual eruptive centers associated with edifices and rift
zones.
This sequence of events is accompanied by characteristic and
repetitive
patterns of tectonic deformation. In order to test the validity
and
broader applicability of this sequence, we compare it with local,
regional, and global mapping published in 17 analyses by other
authors.
This comparison shows that the sequence of units, and thus the
relative
time sequence of the corresponding geologic events, is generally
the
same in virtually all of the widely distributed areas that have
been
studied, comprising about one-half the surface of Venus. We then
address several alternative explanations for the observed
sequence: (1)
that the similar units and sequences correspond to events that
occurred
in different areas at different times (repetitive in different
places
but not time correlative); (2) that the sequences occurred
generally
synchronously in different places (repetitive and rime
correlative);
or (3) that the situation is intermediate between the two cases.
In
order to distinguish among these possibilities, we analyze
evidence
for the lateral global continuity of units, the chronology of
emplacement on the basis of the density of superposed craters,
and
the consistency of stratigraphic relationships based on these
data.
We find that this analysis supports the hypothesis that the
individual
sequences are repetitive in different parts of the planet, and
generally time correlative between these locations. As a further
test of this stratigraphy, we outline a global model for the
geological
evolution of Venus and assess the duration of emplacement of
units, the
timing and style of tectonic phases, and the volumes and implied
fluxes
of volcanic deposits. We find that the morphologically
recognizable
part of the history of Venus comprises only the last 10-20% of
its
total history. Emplacement of tessera-forming material and its
deformation into tessera terrain are the major geologic events of
the
initial Fortunian time. Several stages of areally extensive
volcanism
occurred subsequently burying vast areas of tessera and forming
regional plains during Sigrunian, Lavinian, and Rusalkian times.
The
average global rate of volcanism was a few km(3) y(-1), and the
emplacement of plains was accompanied by alternating episodes of
contraction and extension. The last global-scale distributed
tectonic
episode, the formation of an extensive network of
wrinkle-ridges,:
happened near the end of the Rusalkian Period, and marked the
transition to the present stage of the history of Venus, the
Atlian
Period. Atlian times are characterized by a predominance of
regional
rifting focused at several broad rises, and localized
rift-associated
volcanism in the form of shield volcanic constructions and lobate
volcanic plains-forming units, and is the longest lime duration
among
the stratigraphic units considered, although the resulting
tectonic and
volcanic features and deposits cover only 10-20% of the surface
of
Venus.Comparison of this sequence of events with those revealed
by
continued geologic mapping of Venus will permit further testing
and
assessment so that a consistent and comprehensive documentation
of the
geological record can be presented and used to test models of the
geodynamic evolution of Venus. (C) 1999 Elsevier Science Ltd. All
rights reserved.
=============
(8) AND FINALLY: A TIMELY CLARIFICATION
From Leon Jaroff <NEONLEO@aol.com>
Benny,
please note that my Time story on the asteroid and comet threat,
as
turned in by me, described Meteor Crater as being 3/4 of a mile
across.
Some scientific illiterate slashed the slash before the magazine
went
to press. Well, it happens.
Best regards,
Leon Jaroff
- -
Hi Benny. Here's the last word on the Time asteroid story. Turns
out
that the error was only in the web site, NOT in the magazine.
Whew!!
Best regards,
Leon Jaroff
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