CCNet, 28/2003 -  11 March 2003

"Scientists are arguing again over the idea that the combination of
cataclysms that doomed the dinosaurs 65 million years ago - titanic
volcanic eruptions in India and a meteor impact off the coast of
Mexico - may not have been a coincidence after all. For decades, some
geologists have theorized that the force of an extraterrestrial rock
crashing into Earth could have cracked its crust thousands of miles away
and allowed molten lava to spill out from the interior. But no one
has yet found any solid evidence. Now, though, researchers at University
College London are suggesting that the Indian lava flows are the
impact site of an earlier, larger meteor, and that evidence of the impact
was submerged by upwelling lava. In this view, the mass extinction of
dinosaurs and other creatures was caused not by a single meteor, but
by a barrage of them."
--Kenneth Chang, The New York Times, 11 March 2003

"A large asteroid, one, five or 10 kilometers across, is a different
story because we can see it coming, but we could not do anything about
it. Something that size would end life as we know it, but the best
thing we could do (if one approached) is say nothing."
--Marcello Coradini, European Space Agency, USA Today, 10
March 2003

    The New York Times, 11 March 2003

    USA Today, 10 March 2003


    The Sydney Morning Herald, 10 March 2003

    CCNet, 12 March 1998

    Hermann Burchard <>

    Pavel Chichikov <>


>From The New York Times, 11 March 2003


Scientists are arguing again over the idea that the combination of
cataclysms that doomed the dinosaurs 65 million years ago - titanic volcanic
eruptions in India and a meteor impact off the coast of Mexico - may not
have been a coincidence after all.

For decades, some geologists have theorized that the force of an
extraterrestrial rock crashing into Earth could have cracked its crust
thousands of miles away and allowed molten lava to spill out from the
interior. But no one has yet found any solid evidence.

Now, though, researchers at University College London are suggesting that
the Indian lava flows are the impact site of an earlier, larger meteor, and
that evidence of the impact was submerged by upwelling lava. In this view,
the mass extinction of dinosaurs and other creatures was caused not by a
single meteor, but by a barrage of them.

The new work is provoking another burst of theories and debate over the
demise of the dinosaurs, which has never been explained to everyone's

The new theory, which the researchers described in a scientific journal
recently, holds that a meteor at least 12 miles wide - at least twice as
wide as the one that struck Mexico - would melt some rock, but not nearly
the amount seen in the lava flows, known as the Deccan Traps, which cover
hundreds of thousands of square miles of what is now India.

Rather, the researchers said, the impact would cause "decompression melting"
of already hot rocks deep within the earth. Tens of miles below the surface,
temperatures reach more than 2,000 degrees Fahrenheit but rocks remain solid
because of the high pressure exerted by the rocks weighing down above them.

Computer simulations indicate that once the meteor impact blew away the
overlying rocks, the ones below, relieved of pressure, could then have
turned to lava.

"The whole story is what happens underneath the crater," said Dr. Adrian P.
Jones, a geologist at University College London and lead author of an
article that appeared in Earth and Planetary Science Letters last year.

"It's rather like having a hot-air balloon and a pin. People have calculated
the energy of the pin very accurately, but they've forgotten the balloon is
going bang."

This sequence may have played out several times in Earth's history. Notably,
the largest of all mass extinctions 250 million years ago, at the Permian
geological period and the beginning of the Triassic, coincided with the
creation of lava flows known as the Siberian Traps, the largest of all of
the volcanic eruptions.

There are also intriguing but ambiguous hints of a meteor impact at the
Permian-Triassic boundary. Two years ago, a group of scientists reported
finding buckyballs - durable, soccer-ball-shaped carbon molecules - that
contained helium and argon gases with un-Earthlike chemical signatures.

The scientists said the buckyballs were molecular remnants of the meteor,
but other researchers have been unable to verify the claim. Scientists have
also found slightly elevated levels of iridium - an element common in
meteors - in sediment layers dating to the Permian-Triassic boundary.

While the evidence for a connection any single event is sparse, Dr. Dallas
H. Abbott of Columbia University's Lamont-Doherty Earth Observatory and Dr.
Ann E. Isley of the State University of New York at Oswego say a compelling
picture emerges when looked at over a longer view. They compiled evidence of
meteor impacts and massive volcanic eruptions over most of Earth's history,
dating back four billion years.

Dr. Abbott and Dr. Isley, writing in Earth and Planetary Science Letters,
report that their statistical analysis shows, with 97 percent confidence,
that 9 of 10 periods of heavy meteor bombardment corresponded to periods of
massive volcanism.

Skeptics like Dr. H. Jay Melosh, a professor of planetary sciences at the
University of Arizona, are utterly unconvinced. "I know it's a fun idea," he
said. "I think that's why so many people have been advocating it. It makes a
good discussion after beer. But if you start looking at the details and the
real evidence for this, it really falls apart."

The dates of the ancient meteor impacts and eruptions in Dr. Abbott's and
Dr. Isley's analysis can only be roughly estimated, within tens of millions
of years, and the results depend on how the statistical analysis is
performed. "Some people get correlations, and some people don't," Dr. Melosh

Dr. Melosh also said that decompression melting cannot explain the Deccan
Traps. While the meteor will punch deep into the Earth, the Earth will
almost immediately rebound. "There's a certain amount of willful
misunderstanding here," he said.

Further, he said, there is no evidence anywhere on Earth that meteor impact
has ever caused a volcanic eruption. And scientists still do not have a
convincing model of how an impact could set off an eruption.

But Dr. Jones of University College London said there was evidence that
decompression melting was a viable explanation. He cited Iceland, where, he
said, the melting of glaciers has relieved enough pressure to accelerate
eruptions there.

That is the latest in a multitude of theories that have tried to connect
meteors and volcanoes.

An idea that caught scientists' fancy a decade ago was that a meteor would
not cause volcanism at the impact site, but rather seismic waves from the
impact would pass through the Earth and then focus on the spot opposite the
impact - the antipode - rupturing the crust there.

That would not work as a tidy explanation for the Mexican impact and the
Deccan Trap eruptions. While India is on the opposite side of the world from
Mexico today, it was in a different position 65 million years ago, when the
meteor struck. Also, eruptions began at the Deccan traps a couple of million
of years before the meteor impact in Mexico.

Dr. Jonathan T. Hagstrum, a geophysicist with the United States Geological
Survey who was among the first to propose the idea of antipodal eruptions,
said he believed that a meteor impact in the eastern Pacific Ocean caused
the Deccan Traps eruptions, but that the evidence for it vanished as
tectonic forces pushed that part of the sea floor back into the Earth's

But Dr. Melosh said that regardless of where an impact took place, the
mathematics do not work. Only about one ten-thousandth of the kinetic energy
of an impact is transferred into seismic waves, and the temperature rise at
the other side of the Earth would be about one five-hundredth of a degree,
he said.

Dr. Mark B. Boslough of Sandia National Laboratory said the idea was still
worth investigating. He said his computer simulations, run in the
mid-1990's, predict that even with only one ten-thousandth of the kinetic
energy transferred into seismic waves, the impact would still generate about
six cubic miles of melted rock in the upper mantle at the antipode, although
the melt would be dispersed through a much larger volume.

If the impact instead transferred 5 percent of its energy into seismic
waves, 3,000 cubic miles of melt would be produced. If that melt occurred
beneath a weak portion of the crust, that could perhaps still cause the
volcanism. "I look at this as a possible trigger," he said. "It's worthwhile

Dr. Richard A. Muller, a professor of physics at the University of
California at Berkeley, has proposed an even more novel mechanism of how a
meteor could set off volcanoes: avalanches deep inside the planet.
"Everything else I've seen has struck me as being wrong," he said.

The Earth's inner core is solid, mostly iron, and is growing in size. As
iron in the outer core hardens, pockets of lighter elements like sulfur and
silicon remain in the liquid outer core and start floating upward. As the
droplets rise, temperatures drop by more than 1,000 degrees, and the
droplets condense into flakes "falling like snow" that accumulate in piles
at the boundary between the outer core and the lower mantle, Dr. Muller
said. "Or if you turn it around, rising like foam," he said.

The shock of a meteor impact could cause these piles of flakes to collapse,
exposing part of the mantle to the hot outer core. That hot spot, in turn,
could cause a stream of magma to rise through the mantle to the surface,
where it erupts.

Dr. Muller said the idea, published last year in Geophysical Research
Letters, was fanciful and added that he was offering it more as an
alternative theory to explain why the Earth's magnetic field periodically
flips. (The avalanches would also disrupt the convection currents in the

It may still turn out that the dinosaurs were merely very unlucky.

Copyright 2003, The New York Times

NOTE: For more background info, see CCNet 16/02/02 (EARTH'S VOLCANISM LINKED


>From USA Today, 10 March 2003

By Dan Vergano, USA TODAY

Everybody loves a surprise now and then. But not, it seems, if it involves
official secrecy about an asteroid on a collision course with Earth that
could result in our extinction.

The controversy that followed a science panelist's comments at the recent
American Association for the Advancement of Science meeting seems to have
borne that out.

RAND researcher Geoffrey Sommer started the fracas when an AAAS news release
suggested that he advocates government secrecy to avoid mass panic if a
major-league asteroid strike is ever on the horizon. Sommer studies the
social and economic implications of asteroids - space rocks, sometimes many
miles across - hitting Earth.

Obscured in the ensuing flap, played out mostly in British tabloids and on
the Internet, is the fact that astronomers say they are making real progress
in understanding the actual dangers of nearby asteroids and comets.

"This is a tempest in a teapot," says asteroid expert David Morrison of
NASA's Ames Research Center. "We are all committed to open sharing of our
results with the world."

For his part, Sommer says the AAAS took his comments "rather severely out of
context," and he was only making an argument about the need to find a way to
deflect gigantic asteroids headed for Earth. A flurry of hate mail followed
the news stories, Sommer told the Cambridge Conference Network, a scholarly
electronic network devoted to threats from space hazards.

But he's not the only person in the space business thinking about secrecy.
At a recent asteroid conference near Rome, Marcello Coradini, the head of
the European Space Agency's solar system exploration, told USA TODAY, "A
large asteroid, one, five or 10 kilometers across, is a different story
because we can see it coming, but we could not do anything about it.
Something that size would end life as we know it, but the best thing we
could do (if one approached) is say nothing."

Lost in the debate: For the foreseeable future, "we already know there are
no extinction-level asteroids in Earth-crossing orbits," says Morrison,
writing in an asteroid newsletter.

Spaceguard Survey, a NASA and Air Force collaboration, has been working
since 1993 to catalogue 90% of all nearby asteroids larger than a sixth of a
mile across. The survey has passed its halfway goal, identifying 700 of an
expected 1,100 nearby big space rocks.

None appear headed our way. If any turn up before the project's completion
in 2008, mankind likely will have decades to figure out a deflection scheme,
Morrison says.

Smaller asteroids, ones large enough to cause tidal waves or a regional
catastrophe on impact, do pass by regularly.

In coming years, cautious astronomers probably will describe many newly
discovered asteroids as theoretically approaching Earth until they get a
better trajectory fix and rule out any impact, notes another AAAS meeting
panelist, Clark Chapman of Southwest Research Institute in Boulder, Colo.

In the meantime, scientists already have taken key steps in asteroid
detection and deflection:

In 2001, NASA's NEAR probe landed on asteroid Eros, demonstrating our
ability to land deflecting rockets or bombs on threatening objects.

Expanding the Spaceguard Survey to look for smaller but still significant
asteroids would cost less than a million dollars, according to an Ames
estimate. Additional funding to add a 6-foot mirror-equipped telescope also
would speed the survey and expand capabilities.

A proposal before the European Space Agency calls for a fleet of five small
probes, each 2 feet long, to land on and investigate the properties of
various types of nearby asteroids. Called SIMONE, for Smallsat Intercept
Missions to Objects Near Earth, the probes would help determine how to best
deflect each type. Some asteroids are thought to be solid, iron-rich rocks
while others are only loose collections of dust and rock held together by

Most likely, says Morrison, deflecting a comet or asteroid wouldn't require
planting a bomb on the object, a la Bruce Willis in the movie Armageddon.
Not with a bang but a whimper, a probe gently would land at about 4
miles-per-hour, fire up a low power thruster and alter the asteroid's
trajectory over decades.

"Given several decades of warning and high incentive, I am confident that
such an effort would succeed," Morrison says.

Contributing: Eric Lyman

Copyright 2003, USA Today

MODERATOR'S NOTE: I'm afraid it doesn't help our integrity by blaming the
the AAAS fiasco on British tabloids who were neither present at nor covered
the NEO meeting. In fact, it was experienced science journalists from The
Times, The Independent and The Daily Telegraph who were in the room making
notes and recordings and asking questions. Let's not make matters worse by
being economical with the truth. Benny Peiser


>From, 10 March 2003

By Robert Roy Britt

The tally of Jovian moons has soared to 52 with the discovery of four small
moons added to eight that were previously revealed last week. The total may
represent roughly half of all the giant planet's satellites larger than 0.62
miles (1 kilometer).

The discoveries were made by a team led by Scott Sheppard and David Jewitt
of the University of Hawaii's Institute for Astronomy. They came fast and
furious, in three separate revelations beginning March 5.

"We haven't even had a press release about the satellites," Jewitt said in
an e-mail interview. "We just put up a web site and then we start getting
calls from all over the world. People love this stuff, as we do." 
Included in the latest batch are two rocks estimated to be just 0.62 miles
(1 kilometer) in diameter. These are the first Jovian satellites calculated
to be less than 2 kilometers. Jupiter has 29 moons that are no more than 2.5
miles (4 kilometers) wide and several more that aren't much bigger. These
small satellites are thought to be captured asteroids or chunks of larger
objects that broke apart, though their exact origins have not been
determined. Many of them orbit in a direction opposite the planet's
rotation. asked Jewitt if the tiny objects deserve to be called moons at
all, or whether perhaps a new class of object should be conjured to account
for the micromoons.

"No," Jewitt said to the latter suggestion. "To me they're all natural
satellites. Is a small dog not a dog because it is small?"

Jewitt estimates that Jupiter might have 100 satellites down to the
1-kilometer range, though he stresses that this is just a guess. Countless
smaller rocks and bits of dust are in the planet's gravitational clutches.

No other planet has more known satellites. Saturn has 30, Uranus 21 and
Neptune 11. Each of these planets likely harbors more moons that have not
been spotted because the planets are farther out in the solar system and
harder to examine.

Mars has two moons and Earth has just one, although a separate effort
recently uncovered a quasi-moon that carves an odd path that is
gravitationally bound to our planet. Pluto also has a moon, Charon.

Jupiter has four large satellites, too, called the Galilean moons for their
discoverer. The largest is Ganymede, which is about 3,270 miles (5,262
kilometers) wide.

The new satellites are named S/2003 J1 through S/2003 J12. Jewitt said his
team will continue its search and he expects more discoveries. Using the
Subaru and Canada-France-Hawaii telescopes on Mauna Kea in Hawaii, the team
has found 35 Jovian satellites in recent years.

Copyright 2003,


>From The Sydney Morning Herald, 10 March 2003

By Stephen Cauchi

The solar system, we've been told since primary school, has nine planets.
But a fierce debate raging among astronomers could mean that number being
revised to as low as eight or as high as 12, if not more.

Quaoar, Varuna and Ceres are names students may one day start learning
alongside Mars and Venus. And tiny Pluto may become an asteroid or
"Kuiper-belt object" rather than a planet.

Gibor Basri, an astronomer at the University of California, is about to
submit a controversial proposal to the International Astronomical Union
(IAU), which has naming rights to space objects, that would increase the
number of planets to 12. The IAU has a working group considering the
definition of "planet".

"It's something of an embarrassment that we have no definition of what a
planet is," Professor Basri told his campus newspaper, Berkeley News.
"People like to classify things. We live on a planet; it would be nice to
know what that was."

Professor Basri said that recent discoveries of large asteroids in the
Kuiper belt, on the solar system's fringes, had tested the hazy definition
of "planet". If Pluto, with a diameter of 2300 kilometres, was a planet,
other similar-sized bodies in the solar system should be so regarded, he
said. The 1300-kilometre Quaoar, discovered last year, was the biggest find
in the solar system since Pluto in 1930.

According to Professor Basri's definition, a planet must orbit a star, not
another planet, and it must be round. That means it must be 700 kilometres
in diameter, when gravity moulds it into a sphere, or bigger. Smaller
objects are potato-shaped.

Under his definition, the 900-kilometre asteroid Ceres, discovered in 1801,
would become a planet, as would the Kuiper-belt objects of Varuna,
discovered in 2000, and Quaoar.

"All the accepted, or putative, planets are round," he said in his proposal.
"One can calculate the lower limit for this mass ... it is a little below
the mass of Ceres, or objects less than about 700 kilometres in diameter.
That seems a good place to draw the bottom line for planets."

But other astronomers, if not most, would rather delist Pluto than call
smaller objects like Ceres planets. A New York planetarium in 1999 did not
include Pluto in its display of planets, and the IAU was forced to deny
rumours that year it would delist Pluto. But some academics, like Ross
Taylor of the Australian National University, have already removed Pluto
from planet status in their textbooks.

"Most astronomers now say there are eight planets," Professor Taylor said
last year. "It's arbitrary ... you get into a real semantic sort of swamp.
It's like trying to define life."

At the other extreme, Professor Basri says a planet can't be bigger than 13
times the mass of Jupiter. Because such objects generate heat and light,
they should be called stars.

Professor Basri meets opposition here too. Geoff Marcy, a member of the
Anglo-Australian planet search team at Siding Springs telescope - which has
discovered 13 of these planets - says other factors need to be taken into
account, including how the planet was formed.

"It's way too early to define a planet," he said. "Even though we have now
found over 100 of them, these are still early days in planet hunting."
Copyright  2003. The Sydney Morning Herald


>From CCNet, 12 March 1998


>From Brian Marsden <>
Recent orbit computations on an asteroid discovered last December indicate
it virtually certain that it will pass within the moon's distance of the
earth a little more than 30 years from now. The chance of an actual
collision is small, but one is not entirely out of the question.

The asteroid, known as 1997 XF11, was discovered by Jim Scotti in the course
of the Spacewatch program at the University of Arizona. This program
utilizes modern electronic technology on a 36-inch telescope at Kitt Peak
that was built 77 years ago.

After the discovery observations on December 6, observations made by two
Japanese amateur astronomers during the following two weeks showed that the
minimum distance between the orbits of 1997 XF11 and the earth was very
small. Given also that the object was quite large as earth-approaching
asteroids go, perhaps one mile across, it was added to the list of
"potentially hazardous objects" (PHAs) that need to be monitored, lest they
are destined to come dangerously close to the earth over the course of the
next several centuries. There are currently 108 PHAs.

As astronomers continued to gather data on 1997 XF11, it slowly began to
become apparent that there would be a particularly close approach to the
earth in October 2028. A computation from observations spanning 60 days
suggested that the miss distance would be 500 thousand miles. This distance
may seem large in human terms, but it was less than had previously been
predicted in advance for any other known asteroid during the foreseeable

Observations made on March 3 and 4 by Peter Shelus with a 30-inch telescope
at the McDonald Observatory in western Texas extended the observed arc of
1997 XF11 to 88 days. This time, the orbit computation indicated a miss
distance of only 30 thousand miles from the center of the earth; the earth's
radius is about 4 thousand miles. The time of encounter would be around 1:30
p.m. Eastern Daylight Time on Thursday, October 26, 2028. That evening the
object should be visible with the naked eye. In Europe, where it would be
dark by that time, the object should be a splendid sight as it moves from
northwest to southeast across the sky over a couple of hours.

There is still some uncertainty to the computation. On the one hand, it is
possible that 1997 XF11 will come scarcely closer than the moon. On the
other hand, the object could come significantly closer than 30 thousand
miles. Further observations are necessary in order to
refine the figures. It is also possible that prediscovery observations of
1997 XF11 can be located on archival photographs. Particularly favorable
opportunities for recording the object would have occurred in 1990, 1983,
1976, 1971 and 1957. Ephemerides for these times are available.

It is hoped that continuing observations will be made during the next few
months. The object is starting to move into the dusk and to fade week by
week. Nevertheless, it should be quite accessible for a while with large
telescopes, which in addition to helping establish whether a
collision in 2028 is possible, could usefully provide more definite
information about the object's size.

Further observations of 1997 XF11 should be possible with moderate-sized
telescopes equipped with electronic sensors early in the year 2000. A better
opportunity will occur in late 2002, when the object should be detectable
with quite modest telescopes. On that occasion the closest approach will be
on Halloween, but the miss distance will be a safe 6 million miles.

Brian G. Marsden
1998 March 11



>From Hermann Burchard <>

Dear Benny,

in THE GREAT IMPACT DEBATE V: ENCORE (CCNet 3/10/2003), Clark Chapman
proposes to despin an asteroid and then mount a rocket engine on it to
deflect its orbit.

It is not necessary to despin the asteroid.

Actually, I had an inquiry about this from a NASA related source last Nov
2002 in regard of using an airbag for dynamical coupling (CCNet):

"Dear Hermann,
What if your asteroid is rotating? You can expect a rotation period less
than a couple of hours, and quite likely much less than an hour. Given this
fact, the whole idea appears utterly infeasible."

Here is my reply:

"Dear XXXXX,
actually, I had thought of that!  You can back off and hit it again, at
intervals. Needs a bit more fuel."

In other words, apply what control theorists call a "chattering" or
dis-continuous control. The best case is when the motion best suited to
deflect the asteroid is parallel to a stable principal axis of rotation.
Unfortunately this will be efficient only rarely. Some asteroids wobble
about non-stable axes.




>From Pavel Chichikov <>

Dear Benny,

Re: Asteroids, War and French Bashing - in The Scotsman's joke GWB sits back
to enjoy the destruction of Paris.

If there should be a global crisis of the natural sort, originating on Earth
or in space, our present political disunity will not prepare us to work
together. We may find out then if our species is adaptive or fatally flawed.

Spaceguard would be useless if all we can do is bicker among ourselves.
There's much more to a Spaceguard program than astronomy.

All best wishes,


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