CCNet 42/2001 - 16 March 2001

"When Comet Shoemaker-Levy 9 broke apart and slammed into Jupiter in
1994, earthlings had front-row seats to a spectacle their own planet
hadn't seen in 65 million years. Now, a growing number of
astronomers are asking that people start giving serious thought to how to
deal with the threat of an impact on Earth. Researchers have made
substantial progress in identifying larger near-Earth asteroids.
They now are contemplating building a telescope that would allow
them to spot smaller near-Earth asteroids - space rocks that could inflict
substantial regional damage if they struck. But to Daniel Durda, an
astronomer with the Southwest Research Institute, it's time to focus on
dealing with the threat - from identifying which official or agency gets
the first phone call when a threatening object is identified to
establishing plans for coping with the aftermath of an impact."
--Peter N. Spotts, The Christian Science Monitor, 15 March

"High-resolution images of asteroid 433 Eros taken by the Near Earth
Asteroid Rendezvous (NEAR) Shoemaker spacecraft reveal a surface strewn
with large boulders. Where these boulders came from is an interesting
topic for debate. At the Lunar and Planetary Science Conference in
Houston on Tuesday, a group of scientists suggested that these boulders
might have been shaken to the surface from inside Eros. A logical
explanation for the presence of these boulders is that they are
blocks of material ejected by impacts. If this is the case, planetary
scientists expect to see craters near boulder groupings, and do see this
association on another large asteroid, 243 Ida. On Eros, however, no such
correlation exists."
--Vanessa Thomas,, 15 March 2001

    The Christian Science Monitor, 15 March 2001

    Ron Baalke <>

    SpaceDaily, 16 March 2001

    Andrew Yee <>


    Jacqueline Mitton <>

    Benny J Peiser <>

    Alain Maury <>

    USA Today, 12 March 2001 
     John Twigg <j.twigg@UCL.AC.UK>


     Dell'Oro A,  et al.

     Foschini L

     Markopoulos N

     Ferrin I, et al.

    Goffin E

     Altenhoff WJ, et al.


From The Christian Science Monitor, 15 March 2001

Astronomers push for coherent plan for facing impact

By Peter N. Spotts (
Staff writer of The Christian Science Monitor


When Comet Shoemaker-Levy 9 broke apart and slammed into Jupiter in 1994,
earthlings had front-row seats to a spectacle their own planet hadn't seen
in 65 million years.

Now, a growing number of astronomers are asking that people start giving
serious thought to how to deal with the threat of an impact on Earth.

Researchers have made substantial progress in identifying larger near-Earth
asteroids. They now are contemplating building a telescope that would allow
them to spot smaller near-Earth asteroids - space rocks that could inflict
substantial regional damage if they struck.

But to Daniel Durda, an astronomer with the Southwest Research Institute,
it's time to focus on dealing with the threat - from identifying which
official or agency gets the first phone call when a threatening object is
identified to establishing plans for coping with the aftermath of an impact.

"Scientists have focused on physical and technical issues" surrounding the
threat from near-Earth asteroids (NEAs), says Dr. Durda. "But there's been a
hole in the discussion - the human aspects of the threat."

As if to underscore the havoc that impact events can wreak, researchers from
the University of Washington and the University of Rochester recently
published a study concluding that a giant asteroid or comet probably
contributed to the largest mass extinction in Earth's history.

The extinction marked the transition from the Permian to the Triassic period
250 million years ago. More than 90 percent of all marine species vanished.
On land, widespread extinctions cleared the way for the rise of dinosaurs -
themselves done in by an impactor 65 million years ago.

The team's "smoking guns" lie within tiny soccer-ball shaped formations of
carbon found in 250 million-year-old rock. The formations trapped forms of
helium and argon more similar to those found in meteorites than in Earth's

Durda acknowledges the difficulty of trying to focus public and political
attention on a natural hazard that is rare, but devastating. "People know an
impact is going to happen, but not tomorrow," he says. "This gives them the
weasel room to put off thinking about it."

Even near misses can pose challenges.

In a recent report, Durda and Clark Chapman, also of the SWRI, and Robert
Gold of Johns Hopkins University, note that a close brush with a comet's
tail could destroy many of the communication satellites orbiting Earth -
satellites critical to economic activity worldwide.

Nor are US scientists alone in calling for national and international
efforts to develop approaches to dealing with the threat or the aftermath of
an impact.

Last year, Britain's Parliament established a scientific commission to look
at the near-Earth objects (NEOs) issue. And last month, the government
responded to the commission's report by promising to work more closely with
the European Space Agency on the issue. It apparently declined, however, to
pay for a new telescope to search for near-Earth objects or to establish a
center for them.

The lion's share of search work is done by the US, and more "glass" is being
applied to the effort. Last fall, the Spacewatch program, headquartered at
the University of Arizona, finished work on a 1.8 meter telescope on the
summit of Kitt Peak, near Tucson. Astronomers also have given a high
priority to building an 8.4 meter telescope that, among other projects,
would attempt to catalog 90 percent of near-Earth asteroids greater than 300
meters across within a decade.

Astronomers have been working to catalog NEAs that are 1 kilometer across or
larger. So far, they have found approximately 50 percent of these asteroids,
according to David Morrison, with the National Aeronautics and Space
Administration's Ames Research Center in Mountain View, Calif.

Dr. Chapman, Durda, and Dr. Gold argue that it's time to augment these
surveys with efforts to plan for the day when astronomers discover a
speeding space rock with Earth's name on it. One critical step, they say, is
to be prepared to send unmanned probes to the asteroid to study its
composition and structure. The recently concluded Near Earth Asteroid
Rendezvous mission represents the kind of effort that would be needed, they

Armed with such information, researchers would be in a better position to
recommend ways to deflect or even destroy the asteroid.

The trio holds that the key to coping lies in bringing a broader range of
expertise to bear on the issue and not just leaving it to astronomers.
Climate modelers, seismologists, meteorologists, emergency response
planners, and other groups have expertise that would bear on attempts to
prepare for an impact.

"The dinosaurs could not evaluate and mitigate the natural forces that
exterminated them," the authors write, "but human beings have the
intelligence to do so."

Copyright 2001, The Christian Science Monitor


From Ron Baalke <>, 15 March 2001

A report from this year's Lunar and Planetary Science Conference in Houston
on the mysterious surface of the now-famous asteroid.

by Vanessa Thomas

High-resolution images of asteroid 433 Eros taken by the Near Earth Asteroid
Rendezvous (NEAR) Shoemaker spacecraft reveal a surface strewn with large
boulders. Where these boulders came from is an interesting topic for debate.
At the Lunar and Planetary Science Conference in Houston on Tuesday, a group
of scientists suggested that these boulders might have been shaken to the
surface from inside Eros.

A logical explanation for the presence of these boulders is that they are
blocks of material ejected by impacts. If this is the case, planetary
scientists expect to see craters near boulder groupings, and do see this
association on another large asteroid, 243 Ida. On Eros, however, no such
correlation exists.

"When you look at the surface, you see all these blocks littering the
surface and there are very few craters," University of California (Santa
Cruz) planetary scientist Eric Asphaug pointed out on Tuesday. Either
something wiped out the craters, or some other mechanism transported these
boulders to their present positions on the surface.

At the conference, Asphaug described a problem common in the pharmaceutical
sciences. "Whenever you try to mix powders, they don't mix," he said. "They
segregate according to grain properties." Asphaug and his team think a
similar situation might be taking effect on Eros, "sifting" the largest
rocks to the surface.

Asphaug's group likens the process to shaking a can of mixed nuts. In a
typical can of mixed nuts, Brazil nuts are the largest. When the can is
shaken, the Brazil nuts eventually rise to the surface and the small peanuts
end up at the bottom. Repeated shaking of Eros caused by impacts could cause
the grains and rocks of the asteroid's regolith to sort themselves according
to size.

Like the Brazil nuts, Eros's large boulders rise to the top when the
asteroid is shaken by impacts, and like the peanuts, the fine grains of
Eros's regolith falls through the fractures, grooves, and other crevasses on
the asteroid's surface.

"Everything's undergoing random motions during shaking, and a small grain
can find its way underneath a big grain," Asphaug explained. But, he said,
the opposite will never happen. "The big grain's never going to find a big
enough hole to fall back into." Several small grains would have to all move
out of the way at the same time to allow room for a large grain to move
down. "So statistically, the big grain works its way to the top," Asphaug

But how often would Eros need to be shaken to raise all of the boulders seen
on the surface? According to Asphaug's team, that statistic is hard to pin
down. They do know, however, that it is easier for material to move around
in a low-gravity environment. "Asteroids with very low gravity are more
prone to particle size segregation," Asphaug said. The "Brazil Nut Effect"
would have a more difficult time on a larger body such as Earth or the moon.

If Eros's boulders actually have been shaken to the surface like Brazil nuts
in a can, Asphaug's team suggests that scientists could predict the original
depth of the boulders. "You could make a prediction, if you were bold
enough, to say how deep the asteroid's regolith is by looking at the size
distribution of the crowded surface," Asphaug said. If this is the case, the
boulders sitting on Eros could provide a window to the secrets of the
asteroid's interior.
Copyright 1996-2001 Kalmbach Publishing Co.


From SpaceDaily, 16 March 2001

by Jeff Hecht
Houston - March 17, 2001

Don't worry about contact with aliens from other solar systems-they may be
our distant cousins. According to an American astronomer, there is a slim
chance that microbes could be carried from one solar system to another on
rocks blasted from terrestrial planets by asteroid impacts, spreading life
across the Galaxy.

"About one meteorite ejected from a planet belonging to our Solar System is
captured by another stellar system every 100 million years," Jay Melosh of
the University of Arizona told the Lunar and Planetary Science Conference in
Houston this week.

Although radiation would threaten stowaway microbes, Russell Vreeland of
West Chester University of Pennsylvania says it would be quite possible for
meteorites to carry well-protected organisms over interstellar distances.

In the 1970s, astronomers Fred Hoyle and Chandra Wickramasinghe put forward
the still controversial theory, dubbed "panspermia". This says that comets
bombarding the Earth brought the bacteria and viruses from interstellar
space that started life here 4 billion years ago, and continue to bring in
new biological material today. Melosh argues that alien organisms might also
come from a distant planet similar to our own.

He is part of a group that earlier showed microbes could hitch a ride on
meteorites travelling between planets in our Solar System (New Scientist, 15
January 2000, p 19). At the time, he didn't think any microbes could survive
the millions of years a meteorite would take to travel between stars.

That view changed, however, after Vreeland successfully cultured bacterial
spores from a 250-million-year-old salt deposit in New Mexico (New
Scientist, 21 October 2000, p 12). The longer survival time makes the
transfer of life conceivable, Melosh says.

Transfers between solar systems depend on gravitational interactions between
meteorites and other planets. As a starting point, Melosh considered rocks
blasted off the surface of Mars by impacts.

His simulations show that Jupiter can act as a slingshot, flinging roughly
500 kilograms of Martian rocks each year right out of our Solar System in
all directions. Their velocity averages 5 kilometres per second, so in a
million years they would travel about 17 light years-far enough to reach
nearby stars.

Most ejected meteorites would continue to drift in the interstellar void,
but a few would eventually pass near other planetary systems. "The
probability of direct capture by an Earth-sized planet is very, very tiny,"
says Melosh.

However, the gravity of a Jupiter-sized giant planet can capture meteorites
passing within a hundred million kilometres of it, if the two are moving at
similar velocities in the same direction. The meteorite would then fall into
an eccentric orbit about the star.

It is still far from certain whether the meteorite would go on to collide
with a terrestrial planet, and Melosh's calculations suggest that the
likelihood of such an event is low for a solar system like our own. The
chances would be higher, he says, if terrestrial planets orbited near to a
Jupiter-sized planet.

"The probabilities are pretty low," acknowledges Melosh. But they aren't
impossibilities, he adds. Wickramasinghe believes that his panspermia
theory, in which bacteria can drift on their own between solar systems,
propelled by radiation pressure, is a more likely scenario. "The only
advantage that you might have [with] huge chunks of rock [is that] the
interior is shielded totally from any damaging radiation," he says.

This article will appear in the March 17 edition of News Scientist

Copyright 2001, Space Daily


From Andrew Yee <>

Washington University in St. Louis

Tony Fitzpatrick,, (314) 935-5272

Researchers Pinpoint Region Responsible for Mars' Heyday

St. Louis, Mo., March 15, 2001 -- Planetary scientists at Washington
University in St. Louis and various collaborators have concluded that the
Tharsis rise in Mars' Western Hemisphere is key to many of the Red Planet's
mysteries, including its large-scale shape and gravity field, and its early
climate and water distribution.

Roger J. Phillips, Ph.D., Professor of Earth and Planetary Sciences, and
Director of the McDonnell Center for the Space Sciences, and his colleagues
suggest that an enormous load of volcanic material emplaced at the Tharsis
rise caused global changes to the planet's outer strong
layer, or lithosphere, creating many key features in the landscape. Two
major ones, the Tharsis trough, surrounding Tharsis, and the Arabia bulge,
on the planet's opposite side, are the result of this deformation. These
features, in turn, are essential in the development of the Martian valley
networks, the most common type of drainage system on Mars. Additionally,
water and carbon dioxide released by Tharsis volcanism may have created an
atmospheric greenhouse sufficient to warm the surface to above freezing,
thus enabling running water to form the valleys.

The research was published as part of the March 16, 2001 issue of Science

The Tharsis rise dominates the western hemisphere of Mars. It is a broad,
elevated region rising up to 10 kilometers above its surroundings and
encompassing over 30 million square kilometers. The rise is the site of
large-scale volcanism and extensive fracturing of the crust. Phillips and
colleagues analyzed gravity and topography fields obtained from the Mars
Global Surveyor spacecraft and compared them to a model of how these fields
would behave when the heavy Tharsis volcanic load is dumped onto the
spherical lithospheric shell.

"Imagine that Mars is a beach ball and that the Tharsis load is your fist,"
Phillips said. "As your fist pushes into the beach ball, there is a bulge
created on the opposite side of the ball, and a depression or trough
surrounds your fist. It is that simple."

The model correctly predicts many of Mars' broad-scale gravity and
topography features. The researchers believe that these features were in
place at the end of Mars' oldest time period, the Noachian epoch. This
period extends back to near the planet's origin, estimated at about 4.6
billion years ago, and it ended between 3.8 and 3.5 billion years ago.

According to Phillips, the Tharsis magmas could have produced enough carbon
dioxide and water to induce a climate that was sufficiently warm for liquid
water to be stable on the planet's surface.

"The total release of gases from Tharsis magmas could produce the integrated
equivalent of a 1.5-bar carbon dioxide atmosphere and a global layer of
water that is 120-meters thick," Phillips reported. "Much of the water would
have been lost to space, but even so, these quantities of volatiles are
sufficient to warm the atmosphere to the point at which the surface
temperature is above freezing. The accumulation of atmospheric carbon
dioxide from Tharsis may have made the latter part of the Noachian the most
favorable time for this condition."

The researchers said that the development of the Tharsis trough and Arabia
bulge was a major influence on the location and orientation of Martian
valley networks and outflow channels. They pointed out that nearly all of
the large Martian outflow channels originate in or flow into the Tharsis
trough. The model tested the role of Tharsis loading in valley network
orientations and the researchers concluded that many of these systems,
similar to Earth's river systems, had to have formed after a "significant
fraction" of the Tharsis load was in place. This is because the valleys
follow the downhill direction of the topography induced by the deformation
of Mars in response to the Tharsis load. As these valleys were formed near
the end of the construction of Tharsis, in the latter part of the Noachian
epoch, they may reflect the clement conditions induced by large amounts of
atmospheric carbon dioxide that accumulated from the volcanism that
developed Tharsis.

At the very end of the Noachian epoch, volcanism declined and carbon dioxide
and water were removed from the atmosphere by a combination of factors,
including stripping by the solar wind and thermal escape, among others. The
removal of carbon dioxide and water would have driven surface temperatures
below freezing, and Phillips estimates that this could have occurred in less
than a few hundred million years. The preceding few hundred millions years,
in the latter part of the Noachian, could well be considered Mars' "brief,
shining moment."

"It is possible that during the Noachian Epoch, the structural and volcanic
events associated with Tharsis evolution were the sine qua non that linked
fluvial, geodynamical and climate activity on Mars," Phillips concluded.


From, 14 March 2001

By Leonard David
Senior Space Writer

HOUSTON, Texas -- The Red Planet is alive with surprise.

The constant stream of data relayed from the Mars Global Surveyor (MGS) is
forcing a reexamination and revision of theories about Mars' past and
present, as well as how best to utilize surface and orbital reconnaissance
spacecraft in the future.

From evidence of greater explosive volcanic activity in Mars' past to the
increasing likelihood of finding Martian life today -- the emerging profile
of the planet is a far cry from just a few years ago.

More scientific bombshells are clearly in the offing, say scientists
gathered here at the 32nd Lunar and Planetary Science Conference. Also
tagged in some circles as "rockfest 2001," the five-day event is being held
March 12-16, sponsored by NASA's Johnson Space Center and the Lunar and
Planetary Institute (LPI).

Humbling experience

The now-orbiting Mars Global Surveyor (MGS) has spearheaded a rich
scientific reassessment of that planet's ancient past and its current
status, said Maria Zuber, deputy lead for MGS' Mars Orbiter Laser Altimeter.
She is also professor of geophysics at the Massachusetts Institute of
Technology in Cambridge, Massachusetts.

"From my perspective, pretty much every six months you have a new Mars,"
Zuber said. "In my opinion, the pace of discovery is not lessening with
time," she said.

Data gleaned by the MGS-toted laser have shown a surprising flatness of
Mars' northern hemisphere, Zuber said, with the device now being trained on
the seasonal variability of the polar icecaps and Martian clouds.

"If you had studied Mars 20 years ago and you came to this meeting today,
you would think that people were talking about a different planet that
wasn't the one you studied," Zuber told

"It causes one to be humble...and it's good to be humble," she said.

Subsurface ice

Nadine Barlow, professor of astronomy at the University of Central Florida
in Orlando, said that new data suggest that the crust of Mars is not as
thick as once thought. That thinner crust suggests the planet had an active
heat flow for a long period of time.

The sprawling Valles Marineris -- south of this canyon system is Solis
Planum, perhaps an underground reservoir of ice and liquid water.

Barlow said that she's convinced a giant, near-surface ice reservoir exists
just south of Valles Marineris -- the huge canyon system that cuts across
Mars. "It's a very, very large area of subsurface ice, about the same size
as the state of Arizona," she said.

Future spacecraft, such as the European Space Agency's Mars Express, to be
launched in 2003, will carry radar systems, Barlow said. That gear can
penetrate through the dust-laden surface of Mars and should identify any ice
deposits that may be resident there, very close to the surface, she said.

Volcano watch

Mars experts at the conference suggest that belching volcanoes in certain
areas of the planet were active to recent times, geologically speaking.

Tracy Gregg, assistant professor of geology at the State University of New
York at Buffalo, has lead a team studying Tyrrhena Patera and Hadriaca
Patera, two volcanoes on Mars.

Using both new photos and laser data from the Mars Global Surveyor, these
geologic features are among the oldest, and perhaps longest-lived volcanoes
on Mars, Gregg said.

"Tyrrhena Patera has been active for most of Mars' history. It may still be
active. We don't know," Gregg told "Most agree that Mars, if not
geologically dead now, is dying," she said.

Even if now dormant, long-lived volcanoes might be perfect spots to search
for fossil life, Gregg said. The combination of sustained heat and water is
a nice recipe for life, she said.

Tsunamis on Mars

A team of Japanese researchers from the University of Tokyo reported that
Mars could have been the site of tsunamis. If there were oceans on Mars,
impacts of large meteorites would form a marine target crater, as well as
propagate a rushing wall of water.

According to Isao Takamiya in the Graduate School of Frontier Science at the
University of Tokyo, there is a possibility of finding geological evidence
of tsunami deposits around the shoreline of any ancient ocean on Mars.

They suggest a future spacecraft might be landed within a cratered section
of Mars, called the Western Arabia Shelf. That area had been identified by
other scientists as the site of suspected marine target craters, the
research team reported
Water fights

Hotly debated at the conference is last year's blockbuster announcement that
evidence for liquid water on Mars had been spotted seeping onto the Martian
surface in the geologically recent past.

Not so fast, said Pascal Lee, a NASA researcher at the Ames Research Center
in Moffett Field, California. His research suggests that seasonal snow and
ice melting can carve out features that look similar to those on Mars
thought to be liquid water-formed gullies.

The first two pictures (above) are from the Mars Global Surveyor's Mars
Orbiter Camera (MOC) and show a series of troughs and layered mesas in the
Gorgonum Chaos region of the Martian southern hemisphere.

"It's too early to cry for the need for revolution in our thinking of Mars,"
Lee said.

Another research team, led by D.S. Musselwhite at the Lunar and Planetary
Laboratory at the University of Arizona in Tucson, point to another
possibility. They argue that liquid carbon dioxide, rather than liquid water
may have created the gullies.

Wait-and-see budget

An expedition to Mars is the "what next" in terms of human spaceflight, said
Michael Drake, director of the Lunar and Planetary Laboratory at the
University of Arizona in Tucson. He also chairs NASA's Solar System
Exploration Subcommittee.

Drake said he's taking a wait-and-see-attitude regarding NASA's new budget
in regards to added monies for robotic Mars exploration. In a "sneak peek"
document recently issued by the White House Office of Management and Budget,
the Bush administration blueprint for NASA calls for a "more robust" Mars
exploration effort.

Given added funds, it is not unreasonable that NASA could move up a Mars
return sample mission from 2011 to perhaps as early as 2009, Drake said.
More money could also support a range of smaller, Scout-class spacecraft
dispatched to Mars, he said.

Human treks to the Red Planet

Drake said that the White House budget clearly signals "a vote of no
confidence" in NASA's handling of the space station. That is evident, he
said, by deciding not to build the International Space Station any more
complete than is necessary to accommodate international partners in the

"That savings of billions of dollars plays into the entire question of
what's next for human spaceflight. Is the human spaceflight program simply a
bus service to swap astronauts out on the International Space Station?"
Drake said.

Going back to the Moon has a "been there, done that" feel to it, Drake said.
On the other hand, an expedition to Mars has a better chance of exciting the
American public, he said.

"In my opinion, we have to think about the current robotic Mars program in
this larger context of what's going to happen to the human exploration side.
If, indeed, we start moving in the direction of thinking seriously about
sending humans to Mars, we are going to want to know a lot about Mars
beforehand," Drake said.

Copyright 2001,


From Jacqueline Mitton <>


Date: 15 March 2001                   Ref. PN 01/08 (NAM2)

Issued by: RAS Press Officers

Peter Bond
Phone: +44 (0)1483 268672
Fax: +44 (0)1483 274047

Dr Jacqueline Mitton [NB. Jacqueline Mitton not available 17 - 31 March]
Phone: +44 ((0)1223) 564914
Fax: +44 ((0)1223) 572892


Between Tuesday 3rd and Friday 6th April about 300 professional astronomers
will gather in Cambridge for the National Astronomy Meeting (NAM), one of
the most important astronomy meetings held regularly in the UK which is
hosted this year by the University of Cambridge. The UK Solar Physics
Meeting will also take place in Cambridge in parallel with the NAM.

Media representatives are cordially invited and press room facilities will
be available from 8.30 a.m. on Tuesday 3rd April through to 12.30 p.m. on
Friday 6th April. Scientific sessions are in the Law Faculty Building and
the Lady Mitchell Hall on the University's Sidgwick Site.

To pre-register, contact Peter Bond but advance registration is not
essential. The main registration desk for the meeting will be in the Law
Faculty foyer. Media registration is free. Directions to the press room will
be posted from the registration area.

The press room will be the Lyttleton Room, in nearby Selwyn College. The
phone numbers are:

(0)1223 313724
(0)1223 313754
(0)1223 315553

Press officers' mobile phones will be:

07770 386133 (Jacqueline Mitton) and 07711 213486 (Peter Bond).

The programme and more information about the NAM (including location maps)
can be found at

Abstracts are expected to be available on this web site from 23rd March.

More on the UK Solar Physics Meeting can be found at

A highlight of the week will be a one-day symposium on Thursday 5th April,
entitled 'The Scientific Case for Human Spaceflight'. It marks the 40th
anniversary of the first human space flight by Yuri Gagarin on 12 April
1961. NASA astronaut Jeff Hoffman is one of the speakers. The full programme
for the symposium can be found at

Dr Duncan Steel, author of the recent Time-Life book 'Target Earth' will
give a public lecture with the title 'The Spaceguard Project: Tackling the
Impact Hazard' on Thursday 5 April at 8.15 p.m. in the Lady Mitchell Hall.

Topics to be covered in the science sessions include: extra-solar planets,
galaxies, black holes, X-rays from the universe, cosmology, star formation,
meteorites, first results from Cassini at Jupiter, astronomy from the
International Space Station, sunspots, future space missions and new
observatories. See the web site for details.

There will be an opportunity to visit the Mullard Radio Astronomy
Observatory at Lord's Bridge, just outside Cambridge, between 2.00 and 4.00
p.m. on the afternoon of Friday 6 April.


From Benny J Peiser <>

The press officer of the Royal Astronomical Society has had a couple of
enquiries by local papers in Kent and Bedfordshire about what appeared to be
unusually bright meteors reported by public during the evening of Tuesday 13
March. Kent coastguard was alerted as witnesses thought they were flares.
Reporters from the 'Bedfordshire on Sunday' were saying that they too have
had reports of bright lights falling from the sky on Tuesday evening.


From Alain Maury <>

A new CCD technology which may become interesting in the future: In case you
had not realized, asteroid detection is technology driven. Apart from the
high sensitivity of thinned CCDs, another important factor for survey
instruments is the readout time and the noise. 2 classical solutions are to
use scanning mode (Spacewatch), or frame transfert devices (LINEAR). The
rest of us have to live with relatively long readout times. Up to now,
increasing the readout rate meant increasing the readout noise. This was
truer for certain type of devices. Recently a new technology was developed
at Marconi Applied Technology which allows to break this barrier. Currenty
the size of these devices is too small for survey work, but hopefully in the
future larger devices may become available. For CCNet readers who might be
interested to read a paper on this technology, please see


From USA Today, 12 March 2001 
California unprepared for the Big One

By John Ritter, USA TODAY
SAN FRANCISCO - The West Coast remains vulnerable to catastrophic damage and
loss of life in a major earthquake despite billions of dollars spent to
strengthen buildings and infrastructure.

In the aftermath of three massive earthquakes since 1989 that killed 121
people and caused $51 billion in property losses, progress in quake-proofing
older structures has been slow and fitful, experts say.

Damage from the 6.8-magnitude quake that struck Seattle on Feb. 28 was
modest because it originated deep in the Earth. But with 80% of California's
34 million people living near active faults, a strong quake in the Los
Angeles basin or the San Francisco Bay Area still could be devastating.

"Not nearly enough is being done," says Fred Turner, structural engineer
with the state seismic safety commission. "The state and local governments
should be taking more proactive measures."
Charles Scawthorn, senior vice president of EQE International, the largest
earthquake engineering company, says no region in the world is better
prepared than the Bay Area. ''Yet a huge amount of work still needs to be
done,'' he says, and Los Angeles is in no better shape.

The Seattle quake, which did an estimated $2 billion damage, already is
prodding some officials in high-risk areas to do more.

"We will embark on an expanded retrofitting effort," vows Seattle City
Council member Heidi Wills.

But retrofitting -- a term for strengthening and bracing older structures --
is expensive, disruptive and lengthy.

California's building codes are among the world's strictest. They require
that walls, roofs, floors and foundations be connected to stabilize them and
add strength. But "very few laws have been passed that require older
buildings to have this work done," says Mark Benthien, associate director
for outreach at the Southern California Earthquake Center.

In Seattle, many brick buildings that are not reinforced were damaged
because brick is particularly vulnerable to sways and jolts. Almost half of
California's 25,000 brick buildings have not been retrofitted, despite a
1992 law requiring cities to devise a strategy to make them safer.
Bakersfield, San Bernardino, Riverside, Carmel, El Cerrito, Gilroy, Napa,
Orange, Ontario, Oxnard, Palo Alto and Redwood City are among cities that
have decided not to make such improvements mandatory.

Most brick buildings in Los Angeles, Long Beach and San Jose have been
strengthened -- or condemned. San Francisco, however, has more than 1,000
buildings that still haven't been strengthened. Oakland has more than 300.
San Diego and Sacramento lie outside high-risk areas.

Few of California's tens of thousands of large concrete buildings have been
retrofitted -- warehouses, offices, apartments and parking garages built
from the 1920s through the 1970s.

"They're the ones that pancake in a quake," Scawthorn says.

Retrofitting costs up to several hundred thousand dollars per building.

Although it costs no more than $1,000 to protect a wood-frame house by
bolting its frame to the foundation -- $2,000 to $5,000 if a contractor does
it -- 90% of California homeowners haven't had it done, Turner says.

Old steel-frame skyscrapers were thought to be quake-resistant until some
showed cracks and stress after the 6.8-magnitude 1994 quake in Los Angeles'
Northridge section.

Skyscraper retrofitting is prohibitive: thousands of connections per
building at $30,000 a connection.

"Plus we don't have an example of a collapsed steel-frame building from a
U.S. quake to justify the government stepping in," Turner says.

Newer skyscrapers are built to more rigid standards.

Finding public money for magnificent old public buildings and civic
infrastructure is hard enough. Retrofitting San Francisco's art deco City
Hall cost $200 million; the tab at Los Angeles' City Hall will be $300
million. Pasadena's City Council has not yet found $97 million for its
beaux-arts City Hall. Not long after the Northridge quake, California voters
rejected a $1 billion bond issue to shore up 1,000 highway overpasses and
seven toll bridges.

Government money and tolls have covered only half the $300 million needed to
retrofit the Golden Gate Bridge, which is used by 116,000 vehicles each
weekday. Although it has been 12 years since a section of the San
Francisco-Oakland Bay Bridge collapsed in the 6.9-magnitude Loma Prieta
quake, a $1 billion retrofitting of the bridge's western span won't be
finished until 2003. Work on a new eastern span will start this fall. The
bridge straddles two major faults and carries 279,000 vehicles a day.

State officials say at least 2,200 other bridges, including several large
toll spans, need $4 billion in retrofits.

Many colleges and universities face staggering costs. Dozens of buildings at
the University of California-Berkeley are being strengthened at a cost of
$800 million. But it will be at least five years before progress is
sufficient that a big quake wouldn't close the campus longer than a
semester, says civil engineering professor Nicholas Sitar.

Oil refineries up and down the coast are difficult to retrofit with their
tank farms, stacks and miles of pipes.

A big quake at refinery clusters north of San Francisco or in the Los
Angeles-Torrance area could have ugly results. "There would be tank fires,
oil would spill and large processing units would fall over, causing fires
and release of hazardous materials," Scawthorn says.

Retrofitting the system of dams, aqueducts, pumping stations, water-storage
facilities and 75-year-old pipelines that start in the Sierra Nevada and
bring water to the Bay Area will cost at least $3 billion. A state auditor's
report last year chided water officials' inaction, warning that 2.4 million
customers "are at greater risk of disruptions and water shortages in the
event of a catastrophe."

The piers and huge cranes at major ports in Oakland, Los Angeles and Long
Beach also are susceptible to quake damage, but only Oakland's have
substantial retrofitting.

Half the state's 2,600 hospitals need costly retrofits, and some are
expected to close rather than meet the state's 2008 deadline.

Many building owners can't afford to retrofit, even when financial
incentives and low-interest loans are available. Where rents are high, some
landlords are willing to absorb the cost. But a downside is major disruption
during construction, including lost rents. Most don't have the resources,
the seismic safety commission's Turner says.

Many major companies accustomed to managing risk aggressively have
retrofitted, but few smaller ones have. "People liken it to getting a tooth
pulled," Turner says. "It's not something you want to rush out and do."
Copyright 2001, USAToday


From John Twigg <j.twigg@UCL.AC.UK>

For the past two years, a team funded by the Department for International
Development (DFID) and managed by the British Red Cross has been researching
the work of NGOs in natural disaster mitigation and preparedness.

The project's outputs are now available online.  They comprise:

1. An overview paper that draws together and summarises the research
2. A series of short case studies for project planners, illustrating the
range and nature of NGO work in this area, and highlighting key issues
arising. When it is complete, the series will contain between 15 and 20 case
3. A research study of the mitigation/preparedness work of international
relief and development NGOs based in the UK, and the factors affecting this.
4. Similar research studies of NGOs in Bangladesh, Nicaragua, the
Philippines and Zimbabwe.

These can be downloaded from the project's web page: - click on 'Our Work', then on 'International
Activities', and finally on 'NGO Disaster Mitigation and Preparedness
Project' (for the research reports and overview paper) or NGO Initiatives
in Risk Reduction (for the short case studies).

Questions and comments can be directed to the project's email address
( or the research team leader, John Twigg

15 March 2001



Dell'Oro A, Marzari F, Paolicchi P, Vanzani V: Updated collisional
probabilities of minor body populations ASTRONOMY AND ASTROPHYSICS  366: (3)
1053-1060 FEB 2001

The consistent increase in the discovery rate of new asteroids and Trans
Neptunian Objects (TNOs) in these last years has urged an update of the
values of intrinsic probability of collision and impact Velocity for some
minor body populations. With the statistical method of Dell'Oro & Paolicchi
(1998) we have recomputed tl-le values of impact probability and velocity
for Hilda asteroids, for Trojans vs. Short Period Comets (SPC), and for
TNOs. The algorithm of Dell'Oro and Paolicchi is particularly suited for the
task since it can account for resonant behaviour (Dell'Oro et al. 1998) and
for the clustering of the perihelion longitude of Main Belt asteroids and
Hildas, caused by the presence of a forced component in the eccentricity.
The Hilda population turns out to be well sampled ill the orbital parameter
space since no significant changes are found for the collision frequency
among Hildas, and of Hildas with Main Belt asteroids, although a much larger
sample of orbits has been used in our computations (232 objects) vs. the
smaller group used in previous computation by Dahlgren (1998) (40 objects).
We also computed the impact rate of SPCs vs. Trojans that turned out to be
an order of magnitude lower respect to the Trojans vs. Trojans impact rate.
The relative velocity is instead about 30% higher. Using reasonable
estimates of SPC and Trojan number densities, we find that approximately 1
every 100 collisions involving Trojans may be with all SPC. In the case of
TNOs there is a consistent discrepancy between our values of the collision
probability and impact speed, and those computed by Davis & Farinella
(1997). The consistent increase in the number of known TNOs (186 at present,
only 16 at the time of the Davis and Farinella's work) has led to a better
knowledge of their distribution in the phase space and, consequently, to
more reliable estimates of the collisional probability and impact velocity.

Dell'Oro A, Univ Pisa, Dipartimento Fis, Piazza Torricelli 2, I-56127 Pisa,
Univ Pisa, Dipartimento Fis, I-56127 Pisa, Italy.
Univ Padua, Dipartimento Fis, I-35131 Padua, Italy.

Copyright 2001 Institute for Scientific Information


Foschini L: On the atmospheric fragmentation of small asteroids

It is known, from observational data recorded from airbursts, that small
asteroids breakup at dynamical pressures lower than their mechanical
strength. This means that actual theoretical models are inconsistent with
observations. In this paper, we present a detailed discussion about data
recorded from airbursts and about several theoretical models. We extend and
improve a theory previously outlined for the fragmentation of small
asteroids in the Earth atmosphere. The new condition for fragmentation is
given by the shock wave-turbulence interaction, which results in sudden
outburst of the dynamical pressure.

Foschini L, CNR, Ins TeSRE, Via Gobetti 101, I-40129 Bologna, Italy.
CNR, Ins TeSRE, I-40129 Bologna, Italy.

Copyright 2001 Institute for Scientific Information


Markopoulos N: How much thrust, energy, or propellant does it take to guide
a natural celestial body? JOURNAL OF THE ASTRONAUTICAL SCIENCES  48: (1)
25-43 JAN-MAR 2000

Classical rocket guidance is generalized to the case in which the "rocket"
is a massive, natural celestial body. The main qualitative difference with
thr classical case lies in the gravitational interaction between such a body
and the ejected propellant. The achieved thrust for example is zero for
ejection speeds less than the escape speed from the celestial body. The
theory presented is valid for arbitrary ejection speeds of the propellant.
The effective thrust for guiding such a body is worked out thrice. First,
for propellant ejection at classical speeds, next, for propellant ejection
at the speed of light, and last, for propellant ejection at an arbitrary
speed. All three cases result in the same thrust expression. The most
general last case examines both gravitational interaction effects and mass
loss effects due to conversion into energy using the unifying framework: of
the Schwarzschild solution of general relativity. Gravitational interaction
effects dominate when propellant is ejected at nearly the escape speed,
while effects of mass loss due to conversion into energy dominate when
propellant is ejected at nearly the speed of light. Next, it is shown that
to impart a fixed impulsive velocity change to a celestial body by ejecting
part of it-to be optimized-as propellant one needs a, nonzero, minimum
amount of energy, if the body is massive enough. This constitutes the most
important qualitative difference with classical rocket guidance, in which
case the corresponding minimum energy requirement, for the same problem, is
a trivial zero. The minimum energy turns out to be proportional to the
fourth power of the characteristic length of the celestial body. Thus, for
example, delivering a given velocity impulse requires 10,000 times more
energy for a 20 km asteroid than for a 2 km asteroid. The symmetric case of
minimizing the total mass loss of a celestial body to achieve a fixed
impulsive velocity change corresponds to propellant ejection at the speed of
light. The reverse question of intercepting a celestial body with
"propellant." is also briefly examined. This refers to colliding an external
chunk of mass with a celestial body for the purpose of diverting the
latter's path. The results, applied to two archetypal asteroids with
diameters 20 and 2 km, and densities the same as the Moon's, suggest that
the aforementioned gravitational interaction is not negligible and that,
given enough warning time, the minimum energy requirements for guiding such
objects are achievable.

Copyright 2001 Institute for Scientific Information


Ferrin I, Rabinowitz D, Schaefer B, Snyder J, Ellman N, Vicente B, Rengstorf
A, Depoy D, Salim S, Andrews P, Bailyn C, Baltay C, Briceno C, Coppi P, Deng
M, Emmet W, Oemler A, Sabbey C, Shin J, Sofia S, van Altena W, Vivas K, Abad
C, Bongiovanni A, Bruzual G, Della Prugna F, Herrera D, Magris G, Mateu J,
Pacheco R, Sanchez G, Sanchez G, Schenner H, Stock J, Vieira K, Fuenmayor F,
Hernandez J, Naranjo O, Rosenzweig P, Secco C, Spavieri G, Gebhard M,
Honeycutt K, Mufson S, Musser J, Pravdo S, Helin E, Lawrence K: Discovery of
the bright trans-Neptunian object 2000 EB173 ASTROPHYSICAL JOURNAL 548: (2)
L243-L247, Part 2 FEB 20 2001

We describe the discovery circumstances and photometric properties of 2000
EB173, now one of the brightest trans-Neptunian objects (TNOs) with
opposition magnitude m(R) = 18.9 and also one of the largest Plutinos, found
with the drift-scanning camera of the Quasar Equatorial Survey Team,
attached to the 1 m Schmidt telescope of the National Observatory of
Venezuela. We measure B-V = 0.99 +/- 0.14 and V-R = 0.57 +/- 0.05, a red
color observed for many fainter TNOs. At our magnitude limit m(R) = 20.1 +/-
0.20, our single detection reveals a sky density of 0.915(-0.012)(+0.034)
TNOs per square degree (the error bars are 68% confidence limits),
consistent with fainter surveys showing a cumulative number proportional to
10(0.5mR). Assuming an inclination distribution of TNOs with FWHM exceeding
30 degrees, it is likely that 100 to several hundred objects brighter than
m(R) = 20.1 remain to be discovered.

Ferrin I, Univ Los Andes, Dept Fis, Merida 5101, Venezuela.
Univ Los Andes, Dept Fis, Merida 5101, Venezuela.
Yale Univ, Dept Phys, New Haven, CT 06520 USA.
Yale Univ, Dept Astron, New Haven, CT 06520 USA.
Ctr Invest Astron, Merida 5101A, Venezuela.
Univ Zaragoza, Grp Mecan Espacial, E-50009 Zaragoza, Spain.
Indiana Univ, Dept Astron, Bloomington, IN 47405 USA.
Ohio State Univ, Dept Astron, Columbus, OH 43210 USA.
Carnegie Observ, Pasadena, CA 91101 USA.
Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England.
CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA.

Copyright 2001 Institute for Scientific Information


Goffin E: New determination of the mass of Pallas

Until very recently, the mass of minor planet 2 Pallas had been determined
from its gravitational effects on only I Ceres and the planet Mars. An
independent confirmation was therefore highly desirable. This paper presents
individual mass determinations based on close encounters with 16 other minor
planets, as well as a simultaneous solution using all objects. The resulting
value for the mass of Pallas, (1.17 0.03) 10(-10) M-., essentially confirms
the result from Ceres alone.

Goffin E, Aartselaarstr 14, B-2660 Hoboken, Belgium.

Copyright 2001 Institute for Scientific Information


Altenhoff WJ, Menten KM, Bertoldi F: Size determination of the Centaur
Chariklo from millimeter-wavelength bolometer observations ASTRONOMY AND
ASTROPHYSICS  366: (2) L9-L12 FEB 2001

Using the Max-Planck Millimeter Bolometer Array (MAMBO) at the IRAM 30 m
telescope we detected emission at 250 GHz from the Centaur Chariklo (1997
CU26). The observed continuum flux density implies a photometric diameter.
of 273 km. The resulting geometric albedo is 0.055, somewhat higher than
expected from a comparison with mast of the other few Centaurs and cometary
nuclei for which such data are available.

Altenhoff WJ, Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany.
Max Planck Inst Radioastron, D-53121 Bonn, Germany.

Copyright 2001 Institute for Scientific Information

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