PLEASE NOTE:
*
CCNet 55/2001 - 10 April 2001
----------------------------
"The incoming new ESA director for
science, Dave Southwood, during
a presentation on future developments at
the HQ of the German space
agency today explicitly mentioned NEOs
and Spaceguard as an
important challenge for European
science. This happened in the final
slide of his gripping presentation to
leading German space
scientists, where he emphasized the
central role of ESA's science
program for related endeavours. [...]
Now this does *not* mean that
ESA has set aside specific funds for NEO
research, let alone
mitigation planning [...] But it was
interesting enough that he
mentioned the NEO issue at all - perhaps
because he, as a British,
was influenced by the Task Force report,
or perhaps because there
are indeed negotations going on behind
the scenes for a coordinated
NEO program of many European agencies
...?"
--Daniel Fischer, University of Bonn, 9 April 2001
(1) NEW ESA SCIENCE DIRECTOR SUPPORTS SPACEGUARD
Daniel Fischer <dfischer@astro.uni-bonn.de>
(2) ASTEROID TOUTATIS TO NEAR EARTH IN 2004
Excite News, 9 April 2001
(3) A COMETS ODD ORBIT HINTS AT HIDDEN PLANET
Science News Online, 7 April 2001
(4) THOMAS GOLD REVIVES OLD DEBATE ABOUT MOON TO EXPLAIN DUST IN
EROS
CRATERS
Ron Baalke <baalke@jpl.nasa.gov>
(5) HITCHHIKING MOLECULES COULD HAVE SURVIDED FIERY COLLISIONS
WITH
EARTH
Andrew Yee <ayee@nova.astro.utoronto.ca>
(6) GREENHOUSE GASES 'WILL SAVE EARTH'
The Times, 10 April 2001
(7) TUNGUSKA: WHAT DONE IT?
Matthew Genge <M.Genge@nhm.ac.uk>
(8) MARTIAN ODYSSEY
John Mccue <john.mccue@ntlworld.com>
=======
(1) NEW ESA SCIENCE DIRECTOR SUPPORTS SPACEGUARD
From Daniel Fischer <dfischer@astro.uni-bonn.de>
Dear Benny,
this may be of interest to the community: The incoming new ESA
director
for science, Dave Southwood, during a presentation on future
developments at the HQ of the German space agency today
explicitly
mentioned NEOs and Spaceguard as an important challenge for
European
science. This happened in the final slide of his gripping
presentation
to leading German space scientists, where he emphasized the
central role
of ESA's science program for related endeavours. Astrobiology,
Space
Weather and NEOs were singled out as related major programs to
which ESA
intends to contribute.
Now this does *not* mean that ESA has set aside specific funds
for NEO
research, let alone mitigation planning: The topic didn't show up
in any
of Southwood's more specific funding diagrams for various
political
scenarios (see item 2 of
http://www.astro.uni-bonn.de/~dfischer/mirror/222.html
for details). But
it was interesting enough that he mentioned the NEO issue at all
-
perhaps because he, as a British, was influenced by the Task
Force
report, or perhaps because there are indeed negotations going on
behind
the scenes for a coordinated NEO program of many European
agencies ...?
Daniel Fischer
======
(2) ASTEROID TOUTATIS TO NEAR EARTH IN 2004
From Excite News, 9 April 2001
http://news.excite.com/news/uw/010405/tech-5)
By Andrea Evans
Daily Evergreen
Washington State U.
(U-WIRE) PULLMAN, Wash. -- Fictitious
movies like "Deep Impact" and
"Armageddon" show the drastic effects of what might
happen if an
asteroid were to collide with the Earth. Although the chances of
this
happening any time soon are very slim, in 2004 an asteroid by the
name
of Toutatis will be coming very near the Earth.
Discovered in 1989, Toutatis was named
after an ancient Celtic god
of war, fertility and wealth, meaning "the god of the
tribe." It is one
of the largest known Earth-crossing asteroids, which are
asteroids with
orbits that cross the Earth's orbit, said Scott Hudson,
Washington State
University professor of electrical engineering and computer
science.
This asteroid has an orbit so that every four years it comes
close to
Earth.
"In 2004 it will get just a couple
times the distance of the moon,
which is very close in solar-system terms," Hudson said.
Although there are usually
Earth-crossing asteroids at least once a
month, most of them are not nearly as large as Toutatis, Hudson
said.
Measuring approximately three miles across, this asteroid is
larger than
the entire city of Pullman, which is about two miles across.
Toutatis will be coming very near the
Earth, but there is really no
chance it will actually impact the Earth, Hudson said.
Astronomers use radar telescopes that
can very accurately track the
orbit of such asteroids and even predict where they will be
centuries
from now. Various groups also carefully check these orbits.
Of greater concern, however, are smaller
objects in space that we
cannot see because they are not reflected by the sun.
Objects like these we would not be able
to pick up until they were
here, said Mary Singer, who is on the board of the Spokane
Astronomical
Society.
When Toutatis does pass the Earth in
2004, it will be near enough
to see with the naked eye or binoculars. It will look like a
pinpoint of
light in the sky, or a faint star. If watched night after night,
observers will be able to notice that it moves across the sky,
unlike
stars, Singer said.
The chances of a large meteor impacting
Earth are not very great.
However, if it does happen, the consequences could be extreme,
Hudson
said.
On the other hand, smaller asteroids
that do not get burned up in
the atmosphere do sometimes make it to Earth. For instance, in
the
1950s, a woman in Pennsylvania was sitting in her living room
when an
asteroid about the size of a baseball came through her roof and
struck
her thigh, bruising it, Singer said.
In the meantime, astronomers will
continue to track and look for
potentially hazardous asteroids out there. In the event that an
Earth-crossing asteroid was on track to hit the Earth ... well,
hopefully that will not happen.
(C) 2001 Daily Evergreen via U-WIRE
======
(3) A COMETS ODD ORBIT HINTS AT HIDDEN PLANET
Science News Online, 7 April 2001
From http://c.moreover.com/click/here.pl?e17359563&e=6513
Ron Cowen
Far beyond the solar system's nine known planets, a body as
massive as
Mars may once have been part of our planetary system-and it might
still
be there.
Although the proposed planet would lie too far away to be seen
from
Earth, its gravitational tug could account for the oddball orbit
of a
large comet spotted in the outer solar system a year ago.
Known as 2000 CR105, the comet moves about the sun in a much more
elongated pathway than originally thought, astronomers now find.
Observations over the past year by Brett Gladman of the
Observatoire de
la Côte d'Azur in Nice, France, and his colleagues show that the
comet's
orbit takes it further than 200 astronomical units (AU) from the
sun and
as close as 44 AU. One AU equals the Earth-sun distance of about
150
million kilometers.
Such an oblong orbit is usually a sign that an object has come
under the
gravitational influence of a massive body. But 2000 CR105, which
may be
an escapee from the distant reservoir of comets known as the
Kuiper
belt, never gets anywhere near any of the solar system's familiar
team
of nine planets. Even at its closest approach to the sun, the
approximately 400-km-wide ball of ice comes no closer than 14 AU
to
Neptune, the nearest known candidate for a significant
gravitational
interaction.
The astronomers concede that feeble and random pushes from
Neptune could
have slowly nudged 2000 CR105 into its current orbit. However,
preliminary analysis suggests this scenario isn't likely, note
Gladman,
Matthew Holman of the Harvard-Smithsonian Center for Astrophysics
in
Cambridge, Mass., and their collaborators.
In an article the researchers recently posted on the Internet
(http://arXiv.org/abs/astro-ph/0103435),
they suggest that a massive
body lurking among the tiny, frozen residents of the Kuiper belt
could
have been the culprit.
That object could have been Neptune itself. According to one
theory,
Neptune and Uranus first formed between the orbits of Jupiter and
Saturn
and were then flung out to greater distances from the sun.
If that kick propelled Neptune into the Kuiper belt before the
planet
settled into its current nearly circular orbit, its gravity could
have
caused the orbits of several objects like 2000 CR105 to stretch
into
elongated trajectories.
Alternatively, the comet's orbit could be the handiwork of an
as-yet-unseen planet whose mass lies somewhere between that of
Earth's
moon and Mars, the researchers say. It's likely that such an
object
would have coalesced in the outer solar system from the same
debris that
formed Neptune, Uranus, and the cores of Jupiter and Saturn,
Holman
notes.
There's only a 1 percent chance that a planet could have survived
in the
Kuiper belt or its surroundings over the 4.5-billion-year age of
the
solar system, says Holman. If the planet found a secluded nook of
the
belt, however, it could remain intact today.
If the proposed planet is as massive as Mars, it would have to
lie some
200 AU from the sun-about 7 times Neptune's distance-Holman
calculates.
Were it closer, observers would have spotted it.
A planet lurking in the Kuiper belt now or in the past might also
explain why many members of the belt have orbits that angle away
from
the plane in which the nine known planets orbit the sun.
"Undoubtedly, something [massive] knocked the hell out of
the belt,"
says Harold F. Levison of the Southwest Research Institute in
Boulder,
Colo. "The question is whether it's there now."
The stability of the orbit of 2000 CR105 suggests that any planet
that
influenced the comet's path has long since departed. If
astronomers find
a family of objects similar to 2000 CR105, the nature of their
orbits
could indicate whether the hidden planet is in fact still there,
Levison
says.
From Science News, Vol. 159, No. 14, Apr. 7, 2001, p. 213.
=======
(4) THOMAS GOLD REVIVES OLD DEBATE ABOUT MOON TO EXPLAIN DUST IN
EROS
CRATERS
From Ron Baalke <baalke@jpl.nasa.gov>
http://www.news.cornell.edu/releases/April01/Gold.dust.deb.html
Cornell cosmologist Thomas Gold revives old debate about moon to
explain
movement of dust into craters of asteroid Eros
FOR RELEASE: April 4, 2001
Contact: David Brand
Office: 607-255-3651
E-mail: deb27@cornell.edu
ITHACA, N.Y. -- More than just dust was kicked up when NASA's
Near Earth
Asteroid Rendezvous spacecraft, NEAR Shoemaker, made a successful
landing
on asteroid 433 Eros on Feb. 12. Also disturbed were the
memories of an
experiment carried out more than three decades ago by a student
of Thomas
Gold, professor emeritus of astronomy at Cornell University.
Images of small craters on 22-mile-long Eros, sent back to Earth
by the
NEAR spacecraft's camera, revealed a fine-grain material that has
somehow
found its way to the bottom of the craters. The members of
the NEAR
imaging team, including the team's leader, Cornell astronomer
Joseph
Veverka, expressed puzzlement over the movement of the dust that
had
created flat, smooth floors in craters. There is, they
said, some unknown
mechanism that moves the dust around so that it slides down the
craters'
sides, "ponding" in the bottoms.
Gold was, perhaps, the only observer not surprised. Static
electricity, he
argues, causes dust grains to levitate downhill into the bottom
of craters
-- the same process, he believes, that has filled craters on the
moon. "If
you added a layer 1 micron [0.001 millimeters] thick in the time
since the
Pyramids were built [about 5,000 years ago], you could get a
layer 1
kilometer in depth over a billion years," says Gold, who has
long been
known as one of the world's foremost cosmologists.
"The features on Eros are so similar to those on the moon,
that dust
levitation has now to be reconsidered for all large lunar
features, and
major conclusions of lunar research now have to be
reconsidered," says
Gold.
Electric charges on the grains, he says, were created by
charged-particle
bombardment from the sun's solar wind, a current of ionized atoms
and
particles such as electrons and protons that the sun spews from
its
surface. When electrons with a high enough energy hit the
dust grains,
they either cause the grains to gain more negative charge or more
positive charge, depending on the substance.
"It's a very intriguing possibility
and one which we will be evaluating seriously during the coming
months,"
says Veverka, who is chair of Cornell's astronomy department.
Gold's controversial theory dates back to stormy debates that
continued
through the 1950s into the early 1970s on the geology of the
moon's
impact craters and their flat, dust-filled floors. Gold himself
had written his
first paper on the subject in 1955. And in the late 1960s
his graduate
student, the late Gregory J. Williams, carried out research at
Cornell's
astronomy department, which Gold chaired from 1959 to 1968, into
the
electrostatic agitation of the surface layers of fine rock
powders. In
1976, Williams' Ph.D. dissertation, Electrodynamics and the Moon
--
Transport Mechanisms, expounded many of Gold's theories on the
transportation of dust on the moon.
The laboratory experiments found that dust particles under lunar
conditions move when different grains adopt very different
charges. The electrical
interaction sets up strong electric fields on a very small scale,
allowing
electrical forces to levitate and move the dust particles.
"Based on the details of reflection of sunlight, grains on
the surface had
to be small enough so they could pile on top of each other in a
very loose
formation, which my colleagues called 'fairy castle structures.'
I can't
understand any process that could occur on the moon that would
lift up
material the size of a brick, but I can understand processes that
would
lift up 50-micron-sized grains," says Gold.
This contradicted the view of many geologists, who believed that
lunar
craters typically were filled either by material ejected by
meteoroid and
asteroid impacts or by lava. However, says Gold, the
smoothing and filling
in of craters on the moon and asteroid Eros was not accomplished
by falling
debris from an impact (which would give a "snowed over"
appearance to the
land and rocks) -- and lava flows on tiny Eros are not possible.
"The amount of material that is missing from the craters on
the side of the
moon visible from Earth, if distributed all over that area, would
make a
layer between one and two kilometers deep. You either have
to say that
this material vanished from the moon, which is not likely, or
that it had
migrated downhill just as it would have done on Earth for
different
reasons," says Gold.
The filling in of craters from dust levitation on Eros appears to
Gold to
be similar in nature -- and to be taking place at about the same
rate -- to
the erosion present on the hidden side of the moon, which does
not receive
as intense an electron bombardment from the solar wind as does
the side
facing Earth. Since Eros lies 289 million miles from the
sun, it is hit by
fewer higher energy electrons than the facing side of the moon.
Related World Wide Web sites: The following sites provide
additional information on this news release. Some might not
be part of the
Cornell University community, and Cornell has no control over
their content
or availability.
o Near Earth Asteroid Rendezvous Mission:
<http://near.jhuapl.edu/>
========
(5) HITCHHIKING MOLECULES COULD HAVE SURVIDED FIERY COLLISIONS
WITH
EARTH
From Andrew Yee <ayee@nova.astro.utoronto.ca>
University of California-Berkeley
Contact:
Robert Sanders, 510-643-6998, rls@pa.urel.berkeley.edu
05 April 2001
Hitchhiking molecules could have survived fiery comet collisions
with
Earth, UC Berkeley experiment shows
By Robert Sanders, Media Relations
Berkeley -- Simulating a high-velocity comet collision with
Earth, a team
of scientists has shown that organic molecules hitchhiking aboard
a comet
could have survived such an impact and seeded life on this
planet.
The results give credence to the theory that the raw materials
for life
came from space and were assembled on Earth into the ancestors of
proteins and DNA.
"Our results suggest that the notion of organic compounds
coming from
outer space can't be ruled out because of the severity of the
impact
event," said research geologist Jennifer G. Blank of the
Department of
Earth and Planetary Science in the College of Letters &
Science at the
University of California, Berkeley.
Blank and her colleagues Randy Winans and Mike Ahrens of the
Chemistry
Division of Argonne National Laboratory, and
engineer-mathematician
Gregory Miller of the Applied Numerical Algorithms Group of
Lawrence
Berkeley National Laboratory, will report their preliminary
findings
on April 5 at the national meeting of the American Chemical
Society
in San Diego, Calif. The talk is part of an April 4-5 session on
extraterrestrial organic chemistry organized by Blank and
colleague
Max P. Bernstein, a chemist in the Astrochemistry Laboratory at
NASA
Ames Research Center in California.
Blank's team shot a soda-can sized bullet into a nickel-sized
metal
target containing a teardrop of water mixed with amino acids, the
building blocks of proteins. More than seventy varieties of amino
acids have been found in meteorites -- many the suspected cores
of comets that smashed to earth -- and are presumed to exist in
interstellar dust clouds.
Not only did a good fraction of the amino acids survive the
simulated
comet collision, but many polymerized into chains of two, three
and
four amino acids, so-called peptides. Peptides with longer chains
are called polypeptides, while even longer ones are called
proteins.
"The neat thing is that we got every possible combination of
dipeptide,
many tripeptides and some tetrapeptides," said Blank, a
geochemist.
"We saw variations in the ratios of peptides produced
depending on the
conditions of temperature, pressure and duration of the impact.
This
is the beginning of a new field of science."
Freezing the target to mimic an icy comet increased the survival
rate
of amino acids, she added.
The ballistic test was designed to simulate the type of impact
that
would have been frequent in Earth's early history, some four
billion
years ago, when rocky, icy debris in our solar system accreted to
form
the planets in what must have been spectacular collisions. Much
of the
debris would have resembled comets -- dirty snowballs thought to
be
mostly slushy water surrounding a rocky core -- slamming into
Earth
at velocities greater than 16 miles per second (25 km/sec).
The severity of the laboratory impact was akin to an oblique
collision
with the rocky surface of the Earth -- a comet coming in at an
angle of
less than 25 degrees from the horizon, rather than head on
perpendicular
to the Earth's surface.
"At very low angles, we think that some water ice from the
comet would
remain intact as a liquid puddle concentrated with organic
molecules,"
ideal for the development of life, Blank said. "This impact
scenario
provides the three ingredients believed necessary for life:
liquid
water, organic material and energy."
Benton C. Clark, chief scientist of Flight Systems at Lockheed
Martin
Astronautics, proposed in 1988 that if comets are slowed
sufficiently,
for example by drag from the Earth's atmosphere, some water and
organic
compounds might survive the collision. They would collect in what
he
called a "comet pond" of concentrated organic material
where life
could develop.
Though comet hunter Eugene Shoemaker estimated that in Earth's
early
history only a few percent of comets or asteroids arrived at low
enough
angles, the bombardment would have been heavy enough to deliver a
significant amount of intact organic material and water,
according to
Blank's estimates.
The best known theory of the origin of life on Earth is that it
derived
from complex molecules such as amino acids and sugars produced
early
in the planet's history by electrical discharges in an atmosphere
replete with gases such as methane, hydrogen, ammonia and water.
The
famous Miller-Urey experiment in 1953, conducted by Stanley
Miller
and Harold Urey of the University of Chicago, demonstrated that a
lightening-like discharge in a test tube filled with these
molecules
could produce amino acids.
Other scientists, however, have proposed that the building blocks
of
life arrived from space. Astronomers have detected many kinds of
organic molecules in space, floating in clouds of gas or bound up
in
dust particles. They range from the simplest -- water, ammonia,
methane,
hydrogen cyanide and alcohols, including ethyl alcohol -- to more
complex molecules, including chains of up to eight carbon atoms.
Interestingly, of the more than 70 amino acids found in
meteorites,
only eight of them overlap with the group of 20 which occur
commonly
as structural components of proteins found in humans and all
other
life on Earth.
To test whether water and organic compounds could survive the
high
pressures and high temperatures of a collision, Blank and her
colleagues worked for three years to design a steel capsule that
would not rupture when hit with a mile-per-second (1.6 kilometer-
per-second) bullet fired from an 80-mm bore cannon at the
University
of Chicago and later at Los Alamos National Laboratory. The
target she
and her team developed -- a two-centimeter diameter stainless
steel
disk about a half-centimeter thick -- was able to withstand about
200,000 times atmospheric pressure without bursting.
They filled the small cavity with water saturated with five amino
acids: three from the list of 20 that comprise all proteins in
humans
(phenylalanine, proline and lysine) and two varieties detected in
the
Murchison meteorite (aminobutyric acid and nor-valine). That
meteorite
plummeted to the ground in 1969 in Australia and is thought to be
the
core of a comet.
The liquid contents were analyzed afterwards at Argonne using
liquid
chromatography and mass spectroscopy to determine the species and
concentrations of molecules present.
The survival of a large fraction of the amino acids and their
polymerization during the collision make the idea of an
extraterrestrial origin of organic compounds a strong contender
against the Miller-Urey theory, Blank said.
"About one comet per year arriving in a low-angle impact
would bring
in the equivalent of all the organics produced in a year in an
oxidizing atmosphere by the Miller-Urey electric discharge
mechanism,"
Blank estimated. "An advantage is you get all of it together
in a
puddle of water rather than diluted in the oceans."
The next hitchhikers she plans to subject to a shock test are
bacterial
spores, which some have proposed arrived on Earth via comet to
jump-start evolution.
The work was sponsored by the National Science Foundation, NASA
and the
Department of Energy.
###
NOTE: Jennifer Blank returns from San Diego on April 9, but can
be
reached via email during that time at jenblank@seismo.berkeley.edu
.
Her office phone is 510-643-0540.
==========
(6) GREENHOUSE GASES 'WILL SAVE EARTH'
From The Times, 10 April 2001
http://www.thetimes.co.uk/article/0,,2-112237,00.html
BY SIMON DE BRUXELLES
THE world needs more greenhouse gases to stop the Earth sliding
into a
new Ice Age, according to two scientists.
Professor Sir Fred Hoyle, a past President of the Royal
Astronomical
Society, and Chandra Wickramasinghe, Professor of Astronomy at
the
University of Cardiff, claim that attempts to counter global
warming are
misguided. Their theory, published in the Astrophysics and Space
Science
Journal, has angered environmentalists hoping to salvage the
Kyoto
agreement on greenhouse gases after the US decision to pull out.
Sir Fred and Professor Wickramasinghe believe that the Earth
broke free
of the grip of the Ice Ages after it was struck by a comet 10,000
years
ago. They claim the comet threw large amounts of water into the
atmosphere, creating a powerful "greenhouse" effect of
which we are
still feeling the benefits. They claim the Earth's atmosphere is
becoming "clogged" with particles of cosmic dust that
will eventually
trigger another Ice Age. The only way to counteract the cooling
is for
man to burn more fossil fuels.
Professor Wickramasinghe said: "The greenhouse effect is
something that
actually keeps us going. Perhaps we should be stepping up rather
than
decreasing our greenhouse gas emissions."
Gareth Jones, of the Met Office, said: "Professor
Wickramasinghe is
making a bold statement but there is not a great deal of evidence
to
support this - it goes against most of our findings."
Copyright 2001 Times Newspapers Ltd.
============================
* LETTERS TO THE MODERATOR *
============================
(7) TUNGUSKA: WHAT DONE IT?
From Matthew Genge <M.Genge@nhm.ac.uk>
Andrei Ol'khovatov made some interesting comments on the problems
in
identifying the nature of the Tunguska impactor from geochemical
constraints
alone (CCNet, 4, 2001). It is certain that the geochemical
evidence is
not the conclusive smoking gun and his caution that geochemical
evidence
must be viewed with the context of regional geology is a
particularly valid
point. The most convincing evidence for an extraterrestrial
component in
the event layer at Tunguska is the coincidence of Ir, other
refractory
elements, flat rare earth element patterns and depleted C-14. The
depletion
in C-14 in particular suggestive of an extraterrestrial source.
It seems
unlikely that the simultaneous occurrence of these in the layer
relating to
the event was caused by the fortuitous influx of materials from
neighbouring REE deposits which in anycase usually have
fractionated REE
patterns relative to chondrite.
The geochemical anomalies are evidence for a chondritic impactor
which therefore does oppose the antimatter-hypothesis for the
Tunguska event.
Andrei O'khovatov is, however, correct, the evidence is not
conclusive and does
not entirely rule out the possibility that such an exotic senario
occurred.
To discount the extraterrestrial significance of the geochemical
anomalies
evidence for similar variations in other layers not related to
event are
required. To conclusively demonstrate that an extraterrestrial
component
exists isotopic evidence is required. In the case of
Tunguska, however,
where the projectile was entirely vaporised, isotopic anomalies
associated
with the survival of extraterrestrial organics (other than
graphitic
residues of organics) will provide little or no insight.
Regards,
Matthew Genge
Department of Mineralogy,
The Natural History Museum, London
====
(8) MARTIAN ODYSSEY
From John Mccue <john.mccue@ntlworld.com>
Dear Benny,
Please find attached a contribution to CCNet. I hope you find it
of
value. Please also could you check the distribution list; I think
I have
somehow got on twice! I receive two copies of each issue.
Thanks, and best wishes,
Dr. John McCue, FRAS,
Stockton Sixth Form College, UK.
The Martian Odyssey begins.
Good luck to NASA's latest Martian probe, Odyssey, but there
would not
be so much pressure to succeed if the press were giving due
credit to
the current achievements of the Mars Global Surveyor.
MGS's breath-taking high-resolution pictures show compelling
evidence
not only for the existence of flowing water but also that it
happened in
recent times. My own vote, though, for a significant MGS result
is the
hemispherical assymmetry of the planet shown up by the Mars
Orbiting
Laser Altimeter. The northern hemisphere is low and relatively
smooth
with a thin crust at 40km thickness. The southern half however is
higher
and rougher with a 70km crust.
The Capture Theory of the origin of the planets (Dormand and
Woolfson,
"The Origin of the Solar System", Ellis Horwood, UK,
1989) sustains,
under computer simulation, the formation of two additional
planets they
call A and B, both with masses less than Neptune but much in
excess of
the Earth's, and both in possession of satellites. What
happened to A
and B?
While following their highly-elliptical orbits the early planets
often
must have been lucky to avoid a collision as their orbits
crossed.
Nevertheless, in the time it takes for the planets' orbits to
round off
it is virtually certain that a catastrophe between two of the
early
planets happened.
That was the fate of planets A and B. Planet A was sent
spinning out of
the new solar system for good. Planet B broke into two main
parts, one
becoming Venus and the other the planet Earth. Mercury is a dense
fragment from the metallic core of planet B.
What about Mars and our Moon? and Mars? Dormand and
Woolfson suppose
that they were originally satellites of planet A. The Earthly
fragment
of planet B could then capture the Moon after the coming-together
of A
and B. The Moon and Mars would surely, though, be peppered by
shrapnel-like fragments from the impact. One half of both spheres
would
probably be permanently scarred, and, indeed, the Moon and Mars
both
show hemispherical asymmetries. Our own Moon's asymmetry
has been long
known but MGS has brilliantly verified that of Mars.
Good luck again to Odyssey, and I hope that at least the media
may be
right in their assertion that this could lay the foundation for a
manned
attempt.
--------------------------------------------------------------------
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