PLEASE NOTE:
*
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
2001
"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, Astronomy.com, 15 March 2001
(1) WHEN ASTEROIDS GET TOO CLOSE FOR COMFORT
The Christian Science Monitor, 15 March 2001
(2) A NUTTY EFFECT ON EROS
Ron Baalke <baalke@jpl.nasa.gov>
(3) ALL ABOARD THE METEOR EXPRESS OF LIFE
SpaceDaily, 16 March 2001
(4) RESEARCHERS PINPOINT REGION RESPONSIBLE FOR MARS' HEYDAY
Andrew Yee <ayee@nova.astro.utoronto.ca>
(5) SCIENTISTS EVALUATE A 'NEW MARS'
Space.com, 14 March 2001
(6) UK NATIONAL ASTRONOMY MEETING 2001 AT THE UNIVERSITY OF
CAMBRIDGE
Jacqueline Mitton <aco01@dial.pipex.com>
(7) METEOR SHOWER OVER THE CHANNEL?
Benny J Peiser <b.j.peiser@livjm.ac.uk>
(8) NEW CCD TECHNOLOGY FOR NEO SEARCHES
Alain Maury <alain.maury@obs-azur.fr>
(9) CALIFORNIA UNPREPARED FOR THE BIG ONE
USA Today, 12 March 2001
(10) NGO DISASTER MITIGATION AND PREPAREDNESS PROJECT
John Twigg <j.twigg@UCL.AC.UK>
* ABSTRACTS *
(11) UPDATED IMPACT PROBABILITIES OF MINOR BODY POPULATIONS
Dell'Oro A, et al.
(12) ON THE ATMOSPHERIC FRAGMENTATION OF SMALL ASTEROIDS
Foschini L
(13) HOW MUCH THRUST, ENERGY, OR PROPELLANT DOES IT TAKE TO GUIDE
AN
ASTEROID?
Markopoulos N
(14) DISCOVERY OF BRIGHT TNO 2000 EB173
Ferrin I, et al.
(15) NEW DETERMINATION OF THE MASS OF PALLAS
Goffin E
(16) SIZE DETERMINATION OF THE CENTAUR CHARIKLO
Altenhoff WJ, et al.
============
(1) WHEN ASTEROIDS GET TOO CLOSE FOR COMFORT
From The Christian Science Monitor, 15 March 2001
http://www.csmonitor.com/durable/2001/03/15/p15s1.htm
Astronomers push for coherent plan for facing impact
By Peter N. Spotts (pspotts@nasw.org)
Staff writer of The Christian Science Monitor
KITT PEAK, ARIZ.
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
rocks.
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
say.
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
==============
(2) A NUTTY EFFECT ON EROS
From Ron Baalke <baalke@jpl.nasa.gov>
Astronomy.com, 15 March 2001
http://www2.astronomy.com/Content/Dynamic/Articles/000/000/000/352xcmcd.asp
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
concluded.
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.
=========
(3) ALL ABOARD THE METEOR EXPRESS OF LIFE
From SpaceDaily, 16 March 2001
http://www.spacedaily.com/news/life-01i.html
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
=========
(4) RESEARCHERS PINPOINT REGION RESPONSIBLE FOR MARS' HEYDAY
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Washington University in St. Louis
Contact:
Tony Fitzpatrick, tony_fitzpatrick@aismail.wustl.edu,
(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
magazine.
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.
==========
(5) SCIENTISTS EVALUATE A 'NEW MARS'
From Space.com, 14 March 2001
http://www.space.com/scienceastronomy/solarsystem/new_mars_010314.html
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 SPACE.com.
"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 SPACE.com. "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
project.
"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, Space.com
=========
(6) UK NATIONAL ASTRONOMY MEETING 2001 AT THE UNIVERSITY OF
CAMBRIDGE
From Jacqueline Mitton <aco01@dial.pipex.com>
ROYAL ASTRONOMICAL
SOCIETY
PRESS NOTICE
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
E-mail: 100604.1111@compuserve.com
Dr Jacqueline Mitton [NB. Jacqueline Mitton not available 17 - 31
March]
Phone: +44 ((0)1223) 564914
Fax: +44 ((0)1223) 572892
E-mail: jmitton@dial.pipex.com
UK NATIONAL ASTRONOMY MEETING 2001
AT THE UNIVERSITY OF CAMBRIDGE
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.
PRESS ROOM & CONTACT NUMBERS
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
http://www.ast.cam.ac.uk/~nam2001/
Abstracts are expected to be available on this web site from 23rd
March.
More on the UK Solar Physics Meeting can be found at
http://www.shef.ac.uk/~uksp01
THE CASE FOR HUMAN SPACEFLIGHT
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
http://www.star.ucl.ac.uk/~iac/nam_space_meeting.html
TACKLING THE ASTEROID HAZARD
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.
FROM EARTH TO THE EDGE OF THE UNIVERSE
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.
VISIT THE MULLARD RADIO ASTRONOMY OBSERVATORY
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.
===========
(7) METEOR SHOWER OVER THE CHANNEL?
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
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.
===========
(8) NEW CCD TECHNOLOGY FOR NEO SEARCHES
From Alain Maury <alain.maury@obs-azur.fr>
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
http://www.ast.cam.ac.uk/~optics/cdm/Sub_electron_paper_03.pdf
Alain
=============
(9) CALIFORNIA UNPREPARED FOR THE BIG ONE
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
========
(10) NGO DISASTER MITIGATION AND PREPAREDNESS PROJECT
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
findings.
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
studies.
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:
http://www.redcross.org.uk
- 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
(dmp@redcross.org.uk) or
the research team leader, John Twigg
(j.twigg@ucl.ac.uk).
15 March 2001
=============
* ABSTRACTS *
=============
(11) UPDATED IMPACT PROBABILITIES OF MINOR BODY POPULATIONS
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.
Addresses:
Dell'Oro A, Univ Pisa, Dipartimento Fis, Piazza Torricelli 2,
I-56127 Pisa,
Italy.
Univ Pisa, Dipartimento Fis, I-56127 Pisa, Italy.
Univ Padua, Dipartimento Fis, I-35131 Padua, Italy.
Copyright © 2001 Institute for Scientific Information
===========
(12) ON THE ATMOSPHERIC FRAGMENTATION OF SMALL ASTEROIDS
Foschini L: On the atmospheric fragmentation of small asteroids
ASTRONOMY AND ASTROPHYSICS 365: (3) 612-621 JAN 2001
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.
Addresses:
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
===========
(13) HOW MUCH THRUST, ENERGY, OR PROPELLANT DOES IT TAKE TO GUIDE
AN
ASTEROID?
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
===========
(14) DISCOVERY OF BRIGHT TNO 2000 EB173
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.
Addresses:
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
=========
(15) NEW DETERMINATION OF THE MASS OF PALLAS
Goffin E: New determination of the mass of Pallas
ASTRONOMY AND ASTROPHYSICS 365: (3) 627-630 JAN 2001
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.
Addresses:
Goffin E, Aartselaarstr 14, B-2660 Hoboken, Belgium.
Copyright © 2001 Institute for Scientific Information
===========
(16) SIZE DETERMINATION OF THE CENTAUR CHARIKLO
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.
Addresses:
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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