PLEASE NOTE:
*
CCNet, 71/2000 - 22 June 2000
-----------------------------
"Senator John McCain (R-AZ) took
the Senate floor Tuesday [13 June
00] to talk about one of his favorite
subjects--Congress'
insatiable appetite for pork. In this
case it was the fiscal year
2001 Defense Appropriations Bill that
got McCain's goat. McCain
took ... shots at the Hawaii delegation,
noting that funding for
the Pearl Harbor Shipyard was boosted by
$24 million above the
Navy's $300 million request and that $15
million was added to the
bill for the Maui Space Surveillance
System, ostensibly to improve
the nation's ability to track asteroids.
"I do not intend to
minimize the importance of such
activities, but only the cast of
Star Trek could conceivably have looked
at a list of military
funding shortfalls and concluded that a
total of $19 million had
to be in the fiscal year 2001 budget for
this purpose," McCain
said."
-- Inside
the Pentagon, 15 June 2000
(1) NEW IMAGES OF METEOR IMPACTS ON THE MOON
Andrew Yee <ayee@nova.astro.utoronto.ca>
(2) ASTEROIDS HAVE SEASONS TOO
Ron Baalke <baalke@jpl.nasa.gov>
(3) MARS WATER SPECULATION STARTED IN 1870s
Larry Klaes <lklaes@BBN.COM>
(4) DISCOVERY.COM & SPACEREF.COM JOIN FORCES
Keith Cowing <kcowing@reston.com>
(5) U.S. SENATOR COMMENTS ON ASTEROID MONITORING
General Simon P. Worden, Col, AF/XOC <SimonP.Worden@pentagon.af.mil>
(6) BUSY SKIES OF THE 16th CENTURY
Clark Whelton <cwhelton@mindspring.com>
(7) AND FINALLY: BREAD - THE NEW HEALTH HAZARD
http://www.vision.net.au/~daly/
==============
(1) NEW IMAGES OF METEOR IMPACTS ON THE MOON
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[http://asia.dailynews.yahoo.com/headlines/technology/afp/article.html?s=asia/headlines/000622/technology/afp/First_recording_of_meteors_hitting_the_Moon.html]
Wednesday, June 21, 2000, 3:02 PM EDT
First recording of meteors hitting the Moon
PARIS (AFP) -- Astronomers say they have recorded the first
pictures of
meteors smashing into the Moon, a series of small, sudden impacts
that
occurred during the spectacular Leonid meteorite shower that
illuminated skies last November.
The images show tiny flashes lasting less than a fiftieth of a
second
as five Leonids slammed into the dusty lunar surface at roughly
90-minute intervals, they report in Thursday's issue of Nature,
the
British science weekly.
The pictures were taken by Mexican astronomers, who joined with
Spanish
counterparts in a bid to be the first to capture images of a
meteor
impact. Three of the flashes were corroborated by other
observers, they
say.
Leonids are so called because they appear in the sky in the
region of
the constellation of Leo. They are a stream of minute dust
particles
trailing behind the Tempel-Tuttle comet, which swings close to
the
Earth every 33 years.
The particles have a diameter of between one millimeter (0.04
inch) and
one centimeter (half an inch). They enter the Earth's atmosphere
at
speeds of between 15 and 70 kilometers (10 and 43 miles) a
second,
which makes them glow and burn up.
When the comet passes close to the Sun, as it did last year, more
of
its ice core melts and more dust is released, thus providing a
bigger
show.
The Mexican pictures were recorded on November 18 at Monterrey,
using a
0.2-metre (eight-inch) telescope targeted at the
"night" side of the
Moon -- the part of its face that was in darkness at the time.
The Moon presents the same face to the Earth. This is because it
rotates about its own axis in about 29 1/2 days, which is
virtually
identical to the time it takes to complete its orbit around the
Earth.
The authors say the Leonid pictures are an encouraging start for
meeting the huge technical challenge of recording high-impact
collisions in space. Pictures and other data could reveal more
about
the nature of meteorites and how they impact, which could be
useful for
protecting communications satellites.
Copyright © 2000 Agence France-Presse. All rights reserved.
=================
(2) ASTEROIDS HAVE SEASONS TOO
From Ron Baalke <baalke@jpl.nasa.gov>
Asteroids have Seasons, Too
NASA Science News
http://spacescience.com/headlines/y2000/ast21jun_1.htm
Later this week the Sun will rise over the south pole of asteroid
Eros,
revealing unexplored terrain to the instruments on NASA's
NEAR-Shoemaker spacecraft.
June 21, 2000 -- When NASA's NEAR spacecraft entered orbit around
433
Eros in February 2000, the asteroid was in the middle of northern
summer. Eros's north pole was constantly bathed in sunlight while
southern regions were in total darkness. Three of NEAR's
scientific
instruments depend on reflected sunlight to do their jobs, so
many of
the mission's early results have focused on observations of the
space
rock's northern parts.
Scientists have been waiting expectantly to see more of the
asteroid
and later this week they will get their wish. On June 25, 2000,
the
subsolar point on Eros will cross the asteroid's equator heading
south.
As the Sun rises over Eros's south pole, sunlight will illuminate
terrain that's been hidden from view since NEAR went into orbit
four
months ago.
"We're looking forward to seeing the south polar region of
Eros for the
first time," says Andrew Cheng, the lead scientist for the
NEAR mission
at the Johns Hopkins University Applied Physics Laboratory.
"Once the
Sun rises over the south pole, the oblique lighting there will
highlight features on the surface, which is ideal for taking
pictures."
On Earth, sunrise at the south pole means that southern spring
has
arrived. We don't often think of asteroids as having seasons, but
they
do. Like Earth, Eros passes through two solstices (when the Sun
shines
down over the poles) and two equinoxes (when day and night are of
equal
length) during its 1.76 year circuit around the Sun. The names of
the
seasons on Eros are the same as the ones on our planet -- fall,
winter,
summer, and spring -- but that's where the similarities end.
Seasons on
Eros last different lengths of time (northern spring is only half
as
long as autumn) while the apparent size of the Sun nearly doubles
between fall and spring. The difference in polar surface
temperatures
from summer to winter may be as great as the difference between
liquid
nitrogen and boiling water. Seasons on Eros are truly alien.
Earth's seasons are caused by the 23.5-degree tilt of our
planet's axis
with respect to its orbital plane. Contrary to a widespread
misconception, our planet is not closer to the Sun during summer
--
Earth's orbit is almost perfectly circular. The orbit of Eros, on
the
other hand, is highly elliptical and its spin axis is tilted 89
degrees! In this respect, Eros is similar to the planet Uranus
whose
spin vector is also nearly parallel to its orbital plane.
Uranus's
82-degree tilt is by far the greatest of the nine planets. This
triggers extreme seasons including gigantic storms that are
comparable
in size to North America with temperatures of 300 degrees below
zero.
Although an airless world like Eros doesn't have
"weather" in the same
sense as a planet like Uranus, it does exhibit its own seasonal
extremes. The primary change from season to season involves the
surface
temperature.
"As far as we know, the surface of Eros is a regolith -- a
mixture of
dust and broken rocks of many different sizes" says Cheng.
"If we
assume that the surface of Eros is similar to the surface of the
Moon,
then it must have similar temperature swings between night and
day."
Eros is elongated like a peanut. It rotates every 5.27 hours
around an
axis that goes through the narrow part of the asteroid. Thus, the
"north
pole" is near the middle and the "equator" traces
Eros's long, irregular
circumference.
On the Moon, the temperature at night drops to minus 173 degrees
Celsius, which is colder than liquid nitrogen. At noon, it rises
to
more than 127 degrees Celsius, far hotter than boiling water. As
the
Sun rises this week on southern regions of Eros that have been in
darkness for months, the temperature is likely to skyrocket
hundreds of
degrees.
"Unfortunately, we don't have a way of directly measuring
the surface
temperature of Eros," notes Cheng. "The thermal
infrared spectrum of
the asteroid peaks at a wavelength around 13 microns. We have an
infrared spectrometer on board, but we deliberately chose its
range of
operation to be between 0.8 and 2.6 microns because that's the
best for
mineralogical studies."
Seasons On Asteroid 433 Eros
ORBIT DATA COURTESY JIM McADAMS, NEAR PROJECT TEAM
Apparent size Solar Flux
Season
Date Physical
Eros-Sun of the Sun (relative to
Description distance (as seen from the autumnal
Eros) equinox)
The subsolar
Vernal Sept. 2, point crosses
Equinox '99 the
asteroid's 1.14 AU 0.44
deg. 2.4
equator
heading north.
The sun shines
Summer Dec. 19, down directly
Solstice '99 over
Eros's 1.30 AU 0.34
deg. 1.8
north pole
The subsolar
Autumnal June 25, point crosses
Equinox '00 the
asteroid's 1.76 AU 0.28
deg. 1.0
equator
heading south.
The sun shines
Winter Feb. 1, directly over
Solstice '01 Eros's
south 1.48 AU 0.34
deg. 1.4
pole
Notes: The names of the seasons refer to Eros's northern
hemisphere.
The seasons are reversed in the south. The last column shows the
seasonal intensity of sunlight relative to incident solar
radiation
during Eros's autumnal equinox. These values simply assume that
solar
radiation declines as the inverse square of Eros's distance form
the
Sun.
For an observer on Eros, one of the most striking features of the
asteroid's seasons would be the constantly changing Sun. Eros's
elliptical orbit brings it within 1.13 AU of the Sun and also
carries
it nearly 1.8 AU away. (An AU, or astronomical unit, is the
distance
between the Earth and Sun. It equals 149,597,871 km). During
northern
autumn, the Sun would appear to be 0.28 degrees across; in the
spring,
when Eros is closer to the Sun, it would well to 0.44 degrees.
(The Sun
appears to be 0.5 degrees wide from Earth.)
Facts about Eros
1. Eros circles the Sun once every 1.76 Earth years. It spins on
its axis once every 5.27 hours.
2. Eros is about 21 by 8 by 8 miles (33 by 13 by 13 kilometers)
in
size. Its shape has been compared to a shoe, a
battered boat, or a
peanut.
3. The gravity on Eros is very weak but enough to hold a
spacecraft.
A 100-pound (45-kilogram) object on Earth would
weigh about 1
ounce on Eros.
4. Eros is a "Near-Earth Asteroid" or NEA. Its
next close approach to
Earth will come in January 2012, when it will pass
0.178 AU from our
planet. Although Eros is a NEA, there is no chance
that it will
collide with Earth.
A bigger Sun means a brighter Sun, too. During northern spring
sunlight
falling on Eros is 240% more intense, on average, than it is
during the
fall. This difference would further amplify seasonal changes in
surface
temperature.
Eros's elliptical orbit also affects the length of its seasons
because
the asteroid travels faster when its closer to the Sun than it
does
when it's farther away. For this reason northern spring on Eros
is
three and a half Earth-months long (about the same as the length
of
springtime on our planet) while autumn persists for seven
Earth-months.
These values are reversed in the asteroid's southern hemisphere.
The
planet Mars also has seasons of unequal length because it moves
in an
elliptical orbit, but the effect is much greater on Eros.
NEAR is currently in a 50-km orbit around Eros. It's the first
time a
spacecraft has ever circled an asteroid. On July 7, 2000, the
probe
will begin moving even closer as it descends to an orbit just 35
kilometers from the asteroid's center. The car-sized spacecraft
will
come within several km of the surface before the mission ends in
February 2001, days after the beginning of southern winter on
Eros.
The first in NASA's Discovery Program of low-cost planetary
missions,
NEAR was launched from Cape Canaveral Air Station, FL., on Feb.
17,
1996. The Johns Hopkins University Applied Physics Laboratory in
Laurel, MD., designed and built the NEAR spacecraft and manages
the
mission for NASA.
=================
(3) MARS WATER SPECULATION STARTED IN 1870s
From Larry Klaes <lklaes@BBN.COM>
Florida Today, 22 June 2000
http://www.flatoday.com/space/explore/stories/2000a/062200h.htm
By Tom Breen
FLORIDA TODAY
CAPE CANAVERAL, Fla. - The idea that water might be present on
Mars,
making it possibly suitable for humans, goes back to the late
1870s.
That's when Italian astronomer Giovanni Schiaparelli spotted what
he
described as "canali" on the red planet's surface. The
word means
channels but was interpreted as canals, and that's when
speculation
about a civilization on Mars first arose.
With a possible announcement today that water in liquid form
might have
been spotted beneath the Mars surface by the Global Surveyor
spacecraft, scientists anew will be speculating about the
possibility
of some sort of life there.
"We don't know what they found, but it's conceivable water
could be
seeping out, maybe 200 yards beneath the surface," said John
Brandenburg, a physicist with Aerospace Corp., a Washington-based
organization that works with NASA and other U.S. government
agencies.
During the years, Brandenburg also has become known for his
investigations of the possibility of water existing on Mars, and
in
the 1980s speculated that vast oceans may have been present
hundreds of
millions of years ago. He also is the co-author of a recent book,
Dead
Mars, Dying Earth, which looks closely at both planets.
Since the late 1970s, when the Mariner spacecraft revealed
evidence of
possible geysers, scientists have been holding out hope that
water
existed on Mars. But never before has the possibility existed
that
liquid water could be present on the red planet, Brandenburg
said.
"This could be a big deal; if you have liquid water, you
have
bacteria living in it," he said.
Last year, NASA hoped that the Mars Polar Lander would detect
water ice
at the Martian South Pole. But the mission never took place after
the
spacecraft was destroyed.
The discovery of water in the warmer climes of Mars, south of the
Martian equator, would be far more significant, Brandenburg said.
"Water seepage, rather than ice, is extremely
important," he said.
"If this discovery is borne, it will hasten a human mission
to Mars,"
Brandenburg added.
See these two related online books:
Mars by Percival Lowell, 1895:
http://www.bibliomania.com/NonFiction/Lowell/Mars/index.html
The Planet Mars: A History of Observation and Discovery
By William Sheehan, The University of Arizona Press, Tucson, 1996
http://www.uapress.arizona.edu/online.bks/mars/contents.htm
Copyright 2000, Forida Today
============
(4) DISCOVERY.COM & SPACEREF.COM JOIN FORCES
From Keith Cowing <kcowing@reston.com>
A press release will be out all over the Internet tomorrow
announcing
that Discovery.com has teamed in an exclusive hosting partnership
with
SpaceRef.com/Astrobiology.com/Whole Mars Catalog. We will be
their main
space information engine, news, and research tool.
=============================
* LETTERS TO THE MODERATOR *
=============================
(5) U.S. SENATOR COMMENTS ON ASTEROID MONITORING
From General Simon P. Worden, Col, AF/XOC <SimonP.Worden@pentagon.af.mil>
Benny,
I attach the following comments from Senator John McCain,
sometime U.S.
Presidential Candidate, to illustrate that we still have some
distance
to go in removing the "giggle factor" from asteroid
research.
v/r
S. Pete Worden, Brigadier General (sel), USAF
-------------
Sen McCain's Remarks Regarding Funding Plus-up for Maui Space
Surveillance Site. Inside the Pentagon, 15 Jun 00, reported that
fresh
off of a bare-knuckled (and successful) fight to get a campaign
finance
reform measure added to the Senate's defense authorization bill,
Sen
John McCain (R-AZ) took the Senate floor Tuesday [13 Jun 00] to
talk
about one of his favorite subjects--Congress' insatiable appetite
for
pork. In this case it was the fiscal year 2001 Defense
Appropriations
Bill that got McCain's goat.
McCain took ... shots at the Hawaii delegation, noting that
funding for
the Pearl Harbor Shipyard was boosted by $24 million above the
Navy's
$300 million request and that $15 million was added to the bill
for the
Maui Space Surveillance System, ostensibly to improve the
nation's
ability to track asteroids. "I do not intend to minimize the
importance
of such activities, but only the cast of Star Trek could
conceivably
have looked at a list of military funding shortfalls and
concluded that
a total of $19 million had to be in the fiscal year 2001 budget
for
this purpose," McCain said.
===============
(6) BUSY SKIES OF THE 16th CENTURY
From Clark Whelton <cwhelton@mindspring.com>
"The Comet of 1577," by C. Doris Hellman (Columbia
University Press,
1944), a comprehensive study of medieval astronomy from original
sources, makes no mention of a "circle of fire" being
reported in 1571.
The mid-to-late16th century, however, was a very influential
period in
the development of modern astronomical ideas... many large comets
were
seen, notably in 1566, 1577 and 1618.
The great supernovae of 1572 and 1604 were mortal blows to
Aristotelean-Ptolemaic theory, which held the starry realm to be
unchangeable. This doddering system perished entirely in the
following
decades, when parallax measurements indicated that comets
travelled in
paths far beyond the 52 Earth radii that supposedly separated the
Earth
from the moon.
In his article "Starry Messengers," (The Sciences,
Jan.-Feb. 1992)
Frederic Baumgartner discusses the extraordinary display of
celestial
activity between 1560 and 1630. In 1583, for example, there
was a
great conjunction of Jupiter and Saturn.
Baumgartner comments:
"Conjunctions of Jupiter and Saturn take place throughout
the zodiac
every 20 years in a regular pattern that repeats every 800 years,
beginning at the same location in the initial sign. It was
thought
that the world was created during the first conjunction of
Jupiter and
Saturn in Aries -- the original great conjunction. In that
scheme the
phenomenon of 1583 was the eighth since the creation of the
world.
Great events such as birth of Christ and the reign of
Charlemagne had
always followed great conjunctions.
"Speculation was rampant that the upcoming conjunction would
augur some
great event, perhaps the Second Coming. Since it bore such a
heavy load
of prognostication, astronomers meticulously tracked the paths of
the
two planets. The observations showed that many of the
contemporary
ephemerides -- star tables -- that give the positions of the sun,
the
moon, and the planets by time of day, month and year -- were
grossly in
error. Furthermore, the tables based on Ptolemy's theory were
among the
worst. Many astronomers worked to create new ones. Those
based on Tycho's observations were the best available until the
late 17th century. They also served as the observational basis
for key astronomical theories, particularly Kepler's, in the
succeeding century."
It should also be noted that this period of heavy celestial
activity
also saw Pope Gregory's reform of the Julian calendar
(1575-82).
Personally, I doubt the Julian calendar slipped slowly out of
sync with
the vernal equinox over a period of some1,600 years. Might the
erroneous star tables, active skies and calendar reform of the
16th
century have been interconnected in some way?
Baumgartner concludes his article by noting: "The run of
dramatic
celestial phenomena was unparalleled for a 70-year period: in
addition
to the phenomena I listed earlier -- two of only three supernovas
ever
recorded in Europe, two of the greatest comets ever seen and
unusually
high sunspot activity -- there were two total eclipses of the
sun, a
great conjunction and a transit of Mercury. In the eight decades
since
the the appearance of Comet Halley in 1910, Europe has seen
virtually
none of those events."
=======================
(7) AND FINALLY: BREAD - THE NEW HEALTH HAZARD
From http://www.vision.net.au/~daly/
A recent Cincinnati Enquirer headline read, "Baked bread may
be health
hazard." The article described the dangers of the aromas
emitted from
freshly baked bread. The main danger is that organic compounds of
this
aroma may break down ozone. They point to some frightening
statistics -
* More than 98 percent of convicted felons are bread eaters.
* Fully HALF of all children from bread-consuming households
score
below average on standardized tests.
* More than 90 percent of all violent crimes are committed within
24
hours of eating bread.
* Bread is made from "dough". As little as one pound of
dough can
suffocate a mouse. The average American eats more bread
than that in
a few days.
* Primitive tribal societies that have no bread exhibit a low
incidence
of prostate cancer, Alzheimer's disease, Parkinson's
disease,
arthritis and osteoporosis.
* Bread has been proven to be addictive. Subjects deprived of
bread and
given only water, begged for bread after only two days.
* Most bread eaters are unable to distinguish between scientific
fact
and meaningless statistical babbling.
----------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
----------------------------------------
The CCNet is a scholarly electronic network. To
subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied
or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at http://abob.libs.uga.edu/bobk/cccmenu.html
*
[CCNet addendum]
U.S.-EUROPEAN TEAM MAP ASTEROIDS, SOME OF WHICH COULD THREATEN
EARTH
Cornell University News
http://www.news.cornell.edu/releases/June00/Asteroid.hazards.deb.html
'Treasure map' of inner space shows orbits and sizes of 900 large
asteroids, some of which could threaten Earth
EMBARGOED FOR RELEASE: 2 p.m. EDT, June 22, 2000
Contact: David Brand
Office: (607) 255-3651
E-Mail: deb27@cornell.edu
ITHACA, N.Y. -- A new study portrays the paths of asteroids in
the
inner solar system as a vast Los Angeles-style traffic system
crisscrossed with superhighways along which are hurtling huge,
rocky
projectiles. And in the middle of the highway network, on a
possible
collision path, is the planet Earth.
The study estimates that an armada of asteroids, 900 strong, all
a
kilometer in diameter or larger, present a potential hazard to
life on
Earth. Some pass within a few moon distances of Earth every year.
"Sometime in the future, one of these objects could
conceivably run
into the Earth," warns astronomy researcher William Bottke
at Cornell
University. "One kilometer (about .6 of a mile) in size is
thought to
be a magic number, because it has been estimated that these
asteroids
are capable of wreaking global devastation if they hit the
Earth."
Bottke is lead researcher on a U.S.-French team that has
discovered the
spatial and size distribution of a large group of asteroids
called NEAs
(for near-Earth asteroids), a vast system of orbiting rocks in
inner
space, ranging in size from mere specks to more than 64
kilometers (40
miles) in diameter. The astronomers believe the results of their
observational and computer-based study will better quantify the
likelihood of future catastrophic collisions with Earth. The
survey
also is expected to help observational astronomers in improving
their
search for hard-to-find asteroids that might pose a threat to the
planet.
The team's report, "Understanding the Distribution of
Near-Earth
Asteroids," appears in the latest edition (June 23) of the
journal
Science. The authors, besides Cornell's Bottke, are astronomers
with
the Spacewatch group at the University of Arizona's Lunar and
Planetary
Laboratory and at the Observatoire de la Cote d'Azur in Nice,
France.
Calculating which, if any, of the 900 asteroids identified in the
study
could hit the Earth is tricky, says Bottke. "The problem is
that fewer
than half of these Earth-threatening asteroids have been
discovered so
far. Of those we have found, we can accurately predict whether
they
will strike the Earth over the next hundred years or so, but we
can't
project out several thousands of years. So it's possible some of
these
asteroids eventually will move onto an Earth-collision
trajectory. It's
a dangerous place out there."
The new predictions for the distribution of NEAs in the inner
solar
system, say the astronomers, imply that 40 percent of the
kilometer-or-larger asteroids near Earth already have been
discovered.
The remaining 60 percent, however, might be more difficult to
find,
says Bottke. "Most of these asteroids are too far from Earth
to be
easily detected or are located in regions of the sky that are
challenging for astronomers to survey."
The study's authors refer to their survey as a "NEA treasure
map"
indicating in which orbits most NEAs spend their time. The
researchers
say the new estimate of the number of large asteroids is about
half of
that predicted by similar types of analyses reported in the past
decade
and is slightly larger than an estimate published recently in the
journal Nature.
For many decades there has been good evidence that most of the
small
chunks of rocky or iron material that slam into the Earth's
atmosphere
daily are chips off old blocks of asteroids. Most of the
asteroids in
the solar system revolve around the sun on independent orbits,
corralled between Mars and Jupiter in a formation known as the
main
belt. Occasionally, two of these asteroids -- some of them
hundreds of
miles in diameter -- slam into each other at great speed, causing
chunks of all sizes to be blasted off the surfaces.
Most of this material continues to orbit the sun in the main
belt. But
sometimes the newly formed asteroids migrate to unstable regions
of the
asteroid belt known as resonances, areas where the tiny
gravitational
kicks produced by nearby planets such as Mars, Jupiter or Saturn
can
significantly change asteroid orbits. In some cases, these
changes are
enough to swing asteroids into a possible future collision path
with
the Earth.
To find the location of these potentially threatening and
hard-to-find
projectiles, the researchers used the results of the Spacewatch
group's
10-year search for asteroids in the solar system during which it
has
discovered about 100 NEAs. The problem is that this tally is only
a
small fraction of the predicted number of NEAs. Using a
statistical
technique to compensate for the big gaps, Spacewatch astronomers
were
able to calculate the total number of NEAs but not their
approximate
location. To obtain the orbits of the undetected NEAs, Spacewatch
astronomers combined their NEA population estimates with
theoretical
models, produced by the Cornell and Nice researchers, which show
how
asteroids in the main belt are transported to the near-Earth
environment.
Other authors of the study were Robert Jedicke of the University
of
Arizona and Alessandro Morbidelli, Jean-Marc Petit and Brett
Gladman of
the Observatoire de la Cote d'Azur. The study was funded by NASA
and
the European Space Agency.
Related World Wide Web sites: The following sites provide
additional
information on this news release. Some might not be part of the
Cornell
University community, and Cornell has no control over their
content or
availability.
- University of Arizona, Lunar and Planetary Observatory,
Spacewatch
Project: http://www.lpl.arizona.edu/spacewatch
- Near-Earth Object Program, Jet Propulsion Laboratory:
http://neo.jpl.nasa.gov/
- Asteroid and Comet Impact Hazards, NASA Ames Space Science
Division:
http://impact.arc.nasa.gov/index.html
- Observatoire de la Cote d'Azur: http://www.obs-nice.fr/