PLEASE NOTE:
*
CCNet 21/2001 - 6 February 2001: EROS SPECIAL
---------------------------------------------
"After a fling and a rendezvous, it's time for NEAR to
settle down."
James, R. Asker, Aviation Now, 5 February 2001
"This is the first time we've gotten up close and personal
with one
of the objects that eliminated the dinosaurs."
--Edward J. Weiler, Associate NASA Administrator for Space
Science
"A highly porous body will not be so easily deflected by an
explosion, the experts tell us. This means that deflection by an
emplaced propulsion system that uses reaction mass mined from the
body becomes the method of choice: this is technology relevant to
space
mining, accessing the resources of the asteroids for humanity's
use.
It implies we should be researching how to mine asteroidal
regolith,
and cometary mantle material, and solar powered steamrockets, and
steam powered 'regolith rockets', and mass drivers."
--Mark Sonter, 5 February 2001
(1) SMOOTH ATTEMPT TO LAND ON EROS
Ron Baalke <baalke@jpl.nasa.gov>
(2) CLOSE-UP PICTURES OF EROS TO SHED LIGHT ON MYSTERIOUS IMPACT
CRATERS
Ron Baalke <baalke@jpl.nasa.gov>
(3) ATTEMPTS AT HARD LANDING SET FOR ASTEROID SPACECARFT
Andrew Yee <ayee@nova.astro.utoronto.ca>
(4) NEARING A CRASH LANDING
Scientific American, 5 February 2001
(5) NEW MAP OF PLUTO RELEASED
Larry Klaes <lklaes@bbn.com>
(6) DARK SIDE OF A DIFFERENT MOON
Andrew Yee <ayee@nova.astro.utoronto.ca>
(7) PLANET EARTH ON THE MOVE
BBC Online News, 5 February 2001
(8) IMPACT HAZARD: SOME QUESTIONS FOR RUSSIAN NEO RESEARCHERS
Worth Crouch <doagain@jps.net>
(9) EROS' DENSITY & THE LESSONS FOR PLANETARY DEFENSE
Mark Sonter <sonter@camtech.net.au>
(10) HOLST AND THE PLANETS
Don Barrett <barrett1@lvcm.com >
(11) PLUTO ROMANTICS, AGAIN
Joshua Kitchener <staff@dot-comet.com>
===============
(1) SMOOTH ATTEMPT TO LAND ON EROS
From Ron Baalke <baalke@jpl.nasa.gov>
http://www.news.cornell.edu/releases/Feb01/NEAR.control.bpf.html
Images from outer space: Cornell researchers turn to telemetry
and geometry
to capture distant asteroid
FOR RELEASE: Feb. 5, 2001
Cornell University News Service
Contact: Blaine P. Friedlander, Jr.
Office: 607-255-3290
E-mail: bpf2@cornell.edu
ITHACA, N.Y. -- Will this be the gang that could shoot straight?
For the
past year, engineers and computer programmers from Johns Hopkins
University's Applied Physics Laboratory (APL), assisted by NASA's
Jet
Propulsion Laboratory (JPL) and the imaging team at Cornell
University, have
been figuring out how to slew a spacecraft precisely and aim its
camera
perfectly for the final act of its mission: alighting on an
asteroid.
On Feb. 12 the Near Earth Asteroid Rendezvous spacecraft, known
as NEAR
Shoemaker, will attempt to land on Eros, an Earth-crossing
asteroid about
196 million miles from Earth. In mid-descent, an onboard camera
will point
toward the surface and hopefully send back the best images ever
from a
small, solar-system body. The navigational prowess of APL
and JPL will be
complemented by the imaging expertise of the Cornell research
team.
"It's not like this craft is landing on a sphere. It's
descending on a
potato-shaped rock that is 22 miles long, and the rock has a
large,
saddle-shaped hole on one side. The rock continuously spins
end-over-end.
Geometry is forcing us to land there -- where there is more
motion than at
the poles -- so that NEAR's solar panels face the sun, its
antenna points to
Earth and its camera faces the asteroid," says Cornell space
sciences
researcher Ann Harch. "Other than that, it's
easy."
Use of the navigation team's telemetry, geometry and other
calculations --
for this never-before-attempted maneuver -- required unique
software to
point the camera, and it took more than a year to perfect.
Harch and her
Cornell research colleagues Maureen Bell and Colin Peterson and
programmer
Brian Carcich worked with APL (which built the spacecraft and is
managing
the mission) to develop special computer software that, with
great
precision, displays the shape of Eros and how it will look from
the camera's
point of view. First an exact model of the asteroid's shape had
to be
determined. This shape-model software, called POINTS,
developed by
Cornell's Jonathan Joseph, programmer analyst, and Peter Thomas,
senior
research associate, correlates feature in thousands of images and
plots the
asteroid's trajectory and orientation. From that
information, the program
calculates a detailed three-dimensional asteroid model.
Harch, Bell and Peterson then used Orbit, a computer program
developed at
Cornell by Carcich, to design pointing commands for the
multispectral
imaging camera. Orbit reads input data on the asteroid's location
and spin
orientation, then shows where the craft and camera will
point. The program
also displays how the asteroid will look to the camera at each
instant.
This information allowed Harch, Bell and Peterson to cobble
together command
sequences that were uploaded to NEAR Shoemaker throughout the
mission. The
comands take about 17 minutes for the information to be received
by the
distant spacecraft and the same amount of time for the craft to
send back
confirmation that the data was received.
If all goes as planned, at 10:31 a.m. Eastern time on Feb. 12,
the
spacecraft will commence firing a series of burns -- firing
thrusters away
from the asteroid -- to brake the craft for an anticipated 7 mph
landing.
Control commands to the onboard, multispectral camera will be
uploaded to
the spacecraft. However, if NEAR goes faster or slower than
anticipated,
mission controllers at APL will be able to adjust the craft's
onboard clock
to delay or advance the final photo sequence. "The
spacecraft literally has
to be in the right place at the right time" for the camera
to function as
planned, says Harch.
Reflecting on the five-year mission, Harch says: "This
final week has been
such an emotional one. It was an extraordinary experience working
with these
people to produce such a fabulous result, and all of us feel that
way."
Adds Bell, "Getting this altogether has meant many, many
late nights."
=========
(2) CLOSE-UP PICTURES OF EROS TO SHED LIGHT ON MYSTERIOUS IMPACT
CRATERS
From Ron Baalke <baalke@jpl.nasa.gov>
http://www.news.cornell.edu/releases/Feb01/NEAR.landing.deb.html
Cornell imaging team hopes close-up pictures from asteroid
landing will
solve puzzle of never-before-seen surface features
FOR RELEASE: Feb. 5, 2001
Cornell University News Service
Contact: David Brand
Office: 607-255-3651
E-mail: deb27@cornell.edu
ITHACA, N.Y. -- As NASA's Near Earth Asteroid Rendezvous
spacecraft, known
as NEAR Shoemaker, closes in on asteroid 433 Eros, Cornell
University
astronomers hope that surface details as small as a hand-size
rock will be
captured by the camera before the spacecraft bumps down on the
boulder-strewn surface Feb. 12.
Since last October, the NEAR imaging team has been puzzling over
strange
surface features of Eros seen in new, high-resolution
images. There is the
hope that the close-up images taken in the final few minutes
before the
spacecraft drops onto the surface will help to answer their
questions about
the geology of the 22-mile-long asteroid more than 196 million
miles (316
million kilometers) from Earth.
"Since last October we have seen details of Eros at 1 meter
resolution that
we haven't seen anywhere else before and don't understand,"
says Cornell
astronomer Joseph Veverka, who heads the imaging team.
"That's why we are
so excited about getting close to the surface."
The landing -- what NASA is calling a "controlled
descent" -- is a highly
risky maneuver, involving four thruster firings over four hours
intended to
slow the rate of descent to 7 mph from 20 mph. In the final 45
minutes, when
the spacecraft is about 3.5 to 4.5 miles (about 6 to 7.5
kilometers) from
its landing site at the edge of the crater Himeros, the camera
will begin
taking a new image about every 30 seconds.
The final picture will be captured at just 550 yards (500 meters)
from the
surface, enough to capture details as small as perhaps 4 inches
(10
centimeters) across. Mission leaders at the Applied Physics
Laboratory at
Johns Hopkins University, which built the spacecraft and manages
the NEAR
mission, do not expect images to be transmitted from the surface
because
Eros's spin and topography will almost certainly prevent
communication
between Earth and the craft.
Why does Veverka's team want to get such a close look at Eros'
surface
details? Because, says Veverka, who is professor of
astronomy at Cornell,
his team is frankly puzzled by what it has seen on Eros over the
past few
weeks. Last October, with much of NEAR's mission accomplished,
the
spacecraft was sent into orbit just 4 miles (about 6 kilometers)
or so from
the asteroid's surface. For the first time the imaging team was
seeing
details as small as a yard (.9 meter) across, compared with the
approximately 5.5 yards (5 meters) resolution that had been
captured by the
camera since the spacecraft went into orbit around Eros on Feb.
14, 2000.
"Suddenly, we started seeing things we didn't expect and
hadn't seen on
other surfaces in the solar system," says Veverka.
"It's like another door
has opened."
The biggest surprise, says Cornell researcher Peter Thomas, who
has been
interpreting the geology of the asteroid's surface, "is that
some small
craters and other small depressions have flat, smooth floors,
unlike most
craters you see on Eros and other objects. It looks as if
fine-grain
material has slid down the craters' sides and ponded in the
bottoms."
Apparently, he says, there is some mechanism "we hadn't
anticipated" that
moves fine-grain material around on the surface. Although gravity
on Eros is
only one one-thousandth of that on Earth -- an average person
would weigh
only an ounce or two -- it is still "very effective in
gathering materials
in very flat floors on the bottom of depressions."
Another surprise, says Veverka, is the discovery that some small
boulders
are surrounded by material that appears to have disintegrated
from the
boulders' surfaces. "There is some process that is
very gentle that somehow
disintegrates rock. We haven't seen this on the moon, and we
haven't seen
this before on Eros," he says. "But it seems to
be very common."
It is just possible, says Veverka, that the final image will be
taken almost
at the surface itself. He explains that the camera will remain in
focus
until about 220 yards (200 meters) from the landing site.
If the spacecraft
is still on course, it is possible that the camera will take one
final image
and have time to send a partial image on its way to Earth before
the
spacecraft touches down. It takes 10 milliseconds for the
exposure, 1
second to read the image into the spacecraft recorder and 30
seconds for the
data to emerge from the recorder. The data then take 17 to
18 minutes to
reach Earth tracking stations.
The imaging team now is getting even higher-resolution images of
these
features. On Jan. 24 the spacecraft entered a close flyby
sequence,
including a four-day orbit that produced images from as close as
2 miles
(3.2 kilometers) above the surface. These new images are
enabling the
Cornell imaging team to accumulate data at a resolution of about
1.1 yards
(1 meter). "The hope is that during the descent we can
improve this
resolution by perhaps a factor of 10 so that we can find out more
about what
is going on there," says Veverka.
Related World Wide Web sites: The following sites provide
additional
information on this news release. Some might not be part of
the Cornell
University community, and Cornell has no control over their
content or
availability.
o Near Earth Asteroid Rendezvous Mission: <http://near.jhuapl.edu/>
==============
(3) ATTEMPTS AT HARD LANDING SET FOR ASTEROID SPACECARFT
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[From February 5, 2001 issue of AVIATION WEEK & SPACE
TECHNOLOGY,
http://www.AviationNow.com/content/publication/awst/20010205/near.htm]
Attempt at Hard Landing Set For Asteroid Spacecraft
By JAMES R. ASKER/WASHINGTON
After a fling and a rendezvous, it's time for NEAR to settle
down.
The NEAR Shoemaker spacecraft has completed a successful mission
orbiting
and studying Eros for a year. So why not try to bring the Near
Earth
Asteroid Rendezvous spacecraft to rest on the asteroid? Indeed,
that's
exactly what controllers plan to do next week.
They're calling it a "controlled descent." But labeling
it an attempt to
crash-land might be more to the point, for the spacecraft is not
designed to
land. Even if all goes exactly as planned, it will hit the
surface of Eros
at about 5-7 mph. It could easily tumble and break. And,
controllers
admit they will have to be remarkably lucky to ever again hear
from the
spacecraft once it is down.
The object of trying to maneuver NEAR onto the surface of Eros is
not to
perform a flying tour de force, however, although adding to the
skill set of
planetary mission controllers is an important, secondary
objective.
Rather, the main reason to attempt a hard landing is to gather
"bonus
science" on the way down. Pictures of the surface can be
taken at as high
resolution as possible with this spacecraft's camera. With 5-10
cm. (2-4
in.) resolution, they will be 5-10 times better than the finest
resolution gathered during NEAR's regular mission.
That goal has led the NEAR team to lay out a flight plan that in
some
details is even higher risk than is inherent in the stunt of
landing a
non-lander. But with the 160,000 images and 11 million laser
returns NEAR
has racked up in orbit about the asteroid -- more than 10 times
the data the
mission set out to archive -- there is no reason not to attempt
to get a
handful of images that show even smaller details on Eros'
surface,
scientists say.
"The only risk is in not taking one at this point in the
mission," said
mission director Robert Farquhar of Johns Hopkins University's
Applied
Physics Laboratory (APL).
Edward J. Weiler, the associate NASA administrator for space
science, is
comfortable with the high-risk plan, since NEAR has already
completed all
its science objectives in spades.
"Basically, the mission is a total success story,"
Weiler said, and at $233
million in program costs, "a shining example of the
faster-better-cheaper
philosophy."
Launched in 1996, NEAR arrived at Eros in February 2000 and was
able to
compile a detailed catalog of information on one example of what
were the
building blocks of planets. Weiler added, "This is the first
time we've
gotten up close and personal with one of the objects that
eliminated the
dinosaurs."
The first landing on an asteroid would be a fitting finale to a
string of
firsts for NEAR. It was the first in NASA's Discovery program of
lower cost
planetary missions and the first mission beyond Earth that the
space agency
ever entrusted to an outside organization. NEAR also was the
first
spacecraft ever sent beyond Mars that drew its electrical power
from solar
arrays, not
nuclear devices.
Most significantly, NEAR was the first spacecraft to go into
orbit around a
small body, and made Eros only the sixth object ever orbited by
an
artificial satellite. That was no mean feat since Eros, a rocky,
21-mi.-long
lump has just 1/1000th the gravity of Earth.
NEAR's flight has not been a perfect performance, however. The
biggest
malfunction was the early shutdown of the bi-propellant engine
when NEAR was
first attempting to rendezvous with Eros. It spoiled the attempt
and sent
NEAR flying past its quarry (AW&ST Jan. 4, 1999, p. 30). But
the NEAR team
was able to design a maneuver to fling it back toward the
asteroid and
rendezvous a year later.
The intended landing site is on "the saddle" of the
potato-shaped asteroid,
a concave area the basic shape of which is probably due to a
large impact
crater, which has been named Himeros. NEAR imaging team member
Mark Robinson
of Northwestern University said it was selected because it is
"an exciting
area, geologically" that presents the possibility of looking
in detail at
two distinct terrains.
The landing attempt is set for Feb. 12. It will begin with a
20-sec. burn at
10:31 a.m. EST to take it out of its current orbit of 35 km. (22
mi.) from
the center of Eros.
THE FINAL TIMING CORRECTION of the descent sequence will occur at
1:31 p.m.
Then, the deorbit burn will be followed by four braking maneuvers
-- at 2:16
p.m., 2:31 p.m., 2:47 p.m. and 2:59 p.m., lasting 3 min., 5 min.
12 sec., 6
min. and 4 min. 14 sec., respectively.
The spacecraft will descend at a nearly vertical angle and reach
Eros'
surface at 3:04 p.m. Farquhar described it as "a fairly hard
landing,"
comparing the descent rate to that of a World War II
parachutist's landing.
The NEAR team estimates that it needs to effect a total of 24
meters/sec.
change in velocity on the spacecraft to bring it down on the
surface, and
that the spacecraft has enough hydrazine to achieve about 30
meters/sec.
change.
The spacecraft should be able to relay two or three pictures a
minute back
to Earth. If it lands as hoped, NEAR will come to rest with its
camera
touching the surface and its antenna up. Even if it does, its
view of Earth
will be blocked for 37 min. by the edge of a crater, and with
Eros some 166
million mi. away, even in the best case, confirmation of NEAR's
survival
would be delayed for more than an hour.
NEAR controllers have biased their plans toward getting good
pictures, not
making the difficult landing. For example, the spacecraft will
fire its
mono-propellant system four times, even though it will not be
able to update
parameters of successive burns with information on how well the
previous one
did. Theoretically, the spacecraft could do the burns with
feedback from the
previous firing, but that could be tricky and therefore would put
the
science objective at higher risk.
Alternatively, given the "open loop" nature of each
burn, it would be more
conservative to employ a single firing. But Farquhar said the
safer approach
was ruled out because four would allow for NEAR to spend more
time at lower
altitudes.
There is no chance of gathering science data on the surface,
Farquhar said.
He said, "The most we can hope for is a beacon from NEAR
Shoemaker that says
it's still operating." He put the odds of the spacecraft
landing in working
order and a signal from its omnidirectional antenna being picked
up by
NASA's Deep Space Network at 1%.
"We'll look for a couple of days," Farquhar said, but
no heroic efforts are
planned if NEAR Shoemaker does not "phone home."
Copyright 2001 © AviationNow.com All Rights Reserved.
============
(4) NEARING A CRASH LANDING
From Scientific American, 5 February 2001
http://www.sciam.com/news/020501/2.html
Exactly one week from today on February 12th, the Near Earth
Asteroid
Rendezvous (NEAR) Shoemaker spacecraft will end its five-year,
two-billion-mile mission, making what scientists hope will be a
soft landing
on the asteroid 433 Eros (see animation). The spacecraft, which
began
orbiting Eros on Valentine's Day last year, has collected 10
times more data
than originally planned, including about 160,000 images. "We
have answered
the questions we had when the orbit began," says project
scientist Andrew
Cheng from the Applied Physics Laboratory (APL). "But we
also found many
other things we didn't expect to see and have questions we didn't
know to
ask at the start of the mission. Scientists will be looking at
these data
for years."
Many researchers are anxiously awaiting the last few photos NEAR
Shoemaker
will snap next Monday, which will provide them with the closest
look yet at
a small celestial body. They estimate these pictures could show
surface
features as small as four inches across. The scientists are also
eager to
attempt the craft's controlled decent onto Eros' 6-mile wide
"saddle" area.
"With the spacecraft just about out of fuel and our science
objectives met,
this is a great way to end a successful mission," says NEAR
Mission Director
Robert Farquhar of APL. "It's all bonus science. It's never
been tried
before and it certainly is a complicated set of maneuvers, but at
this point
the only real risk is not taking one."
The plan is to begin moving NEAR Shoemaker out of its current
orbit at about
10:31 a.m., Eastern Standard Time (EST). A series of thruster
firings will
then slow the spacecraft down from a speed of about 20 miles per
hour to 5
miles per hour. It should drift to the surface on its side,
aiming its
telescopic camera towards the landing site. The estimated arrival
time is
just after 3 p.m. EST. Mission operators intend to use blurring
photos,
altitude data from the spacecraft itself, Doppler tracking and
eventually,
the loss of a signal, to determine when NEAR Shoemaker actually
lands.
"The whole sequence of engine burns has to go right, or it
might not be a
very soft touchdown," Farquhar says. "The unknown
nature of the surface
makes it hard to predict what will happen to the spacecraft,
especially
since it wasn't designed to land. The most we can hope for is a
beacon from
NEAR Shoemaker that says it's still operating." --Kristin
Leutwyler
Copyright 2001, Scientific American
===========
(5) NEW MAP OF PLUTO RELEASED
From Larry Klaes <lklaes@bbn.com>
Astronomers from the Southwest Research Institute have produced a
new map of
the surface of Pluto that shows a mysterious dark streak just
above the
equator. The map was produced by watching the shadow of Pluto's
moon Charon
as it passed across the surface of the planet. Each time Charon
passed in
front, the astronomers were able to measure the variations in
light on the
planet's surface. We won't know if the map is accurate until
Pluto is
visited by spacecraft - this isn't expected to happen any earlier
than 2015.
Original Source:
http://www.boulder.swri.edu/recent/pluto_map.html
Internet Coverage:
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1150000/1150197.stm
http://www.cosmiverse.com/space02050102.html
Similar Stories:
http://www.universetoday.com/html/topics/pluto.html
Related Sites:
http://www.universetoday.com/html/directory/astronomy.html
Related Books:
http://www.universetoday.com/html/books/pluto.html
============
(6) DARK SIDE OF A DIFFERENT MOON
From Andrew Yee <ayee@nova.astro.utoronto.ca>
[http://www.nature.com/nsu/010208/010208-4.html]
Monday, 5 February 2001
Dark side of a different moon
By PHILIP BALL
When the Genoese astronomer Giovanni Domenico Cassini discovered
two new
moons orbiting Saturn in 1671, he noticed something curious about
one of
them, now called Iapetus. "One part of [its] surface,"
he said, "is not so
capable of reflecting to us the light of the Sun which maketh it
visible, as
the other part is".
He was right. A dark blotch disfigures Iapetus on its leading
side. New
research suggests this mysterious black eye may be a debris from
one of
Saturn's other moons, Titan [1].
Titan is the one of the most captivating of the 30 or so moons
identified
around Saturn so far. It is slightly bigger than the planet
Mercury and has
an atmosphere thicker than the Earth's -- composed of nitrogen
and
hydrocarbons such as methane. Its surface is far colder than the
Earth's,
but warm enough to perhaps support lakes and rivers of ethane --
a kind of
gasoline planet.
In comparison, Iapetus, a smaller world just 700 kilometres
across, is a
bleak and barren place, with virtually no atmosphere and a rocky,
cratered
surface similar to that on our own moon. Except, that is, for the
dark
plains covering most of one hemisphere. What is this stuff, and
where did it
come from?
Some astronomers think it formed from reactions between methane
and ammonia,
released from Iapetus's rocky guts by volcanic eruptions. Others
suggest
that the moon swept up the dark dust from space. After studying
light
reflected from it, Tobias Owen of the University of Hawaii and
his
colleagues now offer a fresh explanation.
The murky deposit absorbs much of the sunlight falling on it, but
enough
reflects to carry a potential fingerprint of the material's
identity. Just
as plant chlorophyll has its own distinctive green that
identifies it in the
light reflected from a leaf, so the light spectra from Iapetus's
dark patch
can reveal what chemical substances it contains.
From such observations, researchers have previously concluded
that the
material is largely organic: made from carbon-containing
compounds. One of
their favourite chemical candidates is a kind of polymer formed
from
hydrogen cyanide, called poly-HCN.
But to pin down exactly what Iapetus's dark stain is made from,
astronomers
need measurements of the light spectra at longer, infrared
wavelengths.
Owen's team obtained such spectra using the UK Infrared Telescope
on Hawaii,
and then searched for a plausible mixture of ingredients that
could be
behind them, like mixing pigments to match paint to a particular
colour.
The best match, they say, comes from a blend of ice, 'amorphous
carbon'
(basically like soot) and a solid substance called tholin -- a
mixture of
organic molecules formed by passing electrical sparks through
nitrogen and
methane gases. Both Titan and Neptune's moon Triton are believed
to harbour
tholin on their surfaces.
A massive meteorite impact on Titan, the researchers say, could
have sprayed
the organic matter into orbit around Saturn, staining Iapetus as
the moon
passed through the debris. Perhaps, they add, the tiny, reddish
moon
Hyperion, which orbits between Iapetus and Titan, is a relic of
this impact.
1. Owen, T., C. et al. Decoding the Domino: the dark side of
Iapetus. Icarus
149, 160-172 (2001).
© Macmillan Magazines Ltd 2001 - NATURE NEWS SERVICE
===========
(7) PLANET EARTH ON THE MOVE
From BBC Online News, 5 February 2001
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1154000/1154784.stm
By BBC News Online science editor Dr David Whitehouse
Mankind will soon have the ability to move the Earth into a new
orbit, say a
team of astronomers. The planetary manoeuvre may more than double
the time
life can survive on our planet, they believe.
Our initial analysis shows that the general problem of long-term
planetary
engineering is almost alarmingly feasible
Our Sun will increase its brightness in the next billion years or
so, and if
the Earth stays in its present orbit it will be fried and all
life
eliminated.
Using the well-understood "gravitational sling shot"
technique that has been
employed to send space probes to the outer planets, the
researchers now
think a large asteroid could be used to reposition the Earth to
maintain a
benign global climate.
It is an "alarmingly simple" technique, the astronomers
say. It could ensure
humanity's survival and even allow our descendants to alter our
Solar System
to move moons and planets to make new Earths.
The astonishing idea has been put forward by Don Korycansky, of
the
University of California, along with Gregory Laughlin, of the US
space
Agency Nasa, and Fred Adams, of the University of Michigan.
FULL STORY at
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1154000/1154784.stm
============================
* LETTERS TO THE MODERATOR *
============================
(8) IMPACT HAZARD: SOME QUESTIONS FOR RUSSIAN NEO RESEARCHERS
From Worth Crouch <doagain@jps.net>
Dear Dr. Peiser:
Russian scientists were quoted in CCNet, 5 February 2001 as
saying things
about asteroids, or any danger from space, that seem to conflict
with views
and data from both NASA and the January 2001 issue of SPACE UK,
as it was
reported in CCNet. The following Russian statements seem to need
greater
explanation as I indicate by my comments after each statement:
1) Professor Mikhail Smirnov of Russia's Institute of Astronomy
was quoted
as saying, "The flight paths of all asteroids expected near
Earth's orbit
between now and 2176 have been mapped, and none of them foresee a
collision
with the Earth, though longer-term forecasting is not possible
without more
powerful computers." According to the Near Earth Object Task
Force Chairman
Harry Atkinson, as he referred to NASA, not all of the NEO's
which I assume
includes NEAs have been discovered. If this is the case how could
a more
powerful computer be if assistance in predicting unknown
asteroids and their
unknown orbits?
2) Also using the same unknown asteroid reasoning why is the
Professor so
sure when he elaborated, "He added that intermittent rumours
an asteroid was
going to collide with the planet were "fiction or a sign of
incompetence." I
sight NASA's data bank and surprised scientists, "One of the
most recent
close calls occurred on March 23, 1989, when an asteroid
0.25-mile (0.4-
kilometer) wide came within 400,000 miles (640,000 kilometers) of
Earth.
Surprised scientists estimated that Earth and the asteroid --
weighing 50
million tons and traveling at 46,000 miles/hour (74,000
kilometers/hour) --
had passed the same point in space just six hours apart."
3) In his conclusion Professor Smirnov believes that a real
asteroid threat
does not exist when he states, "If a real asteroid threat
does appear in the
future, humankind will undoubtedly find a way to prevent
it." However,
hasn't it been determined by most in the scientific community
that, "On June
30, 1908, a small asteroid 330 feet (100 meters) in diameter
exploded over
the remote region of Tunguska in Siberia, devastating more than
half a
million acres of forest." If the 1908 asteroid had exploded
over Moscow I
think Professor Smirnov must conclude that it had been a real
threat. Again
according to the Near Earth Object Task Force Chairman Harry
Atkinson, " . .
. 300 metre asteroids are much more numerous and can cause great
damage on a
regional scale. If a 300 metre object hit the sea - the most
likely place,
as water covers two-thirds of the Earth's surface - the large
tsunami (tidal
wave) created would have very serious consequences on the
coastlines of
countries many thousands of miles away." Professor Smirnov
did, however, to
his credit acknowledge the threat of smaller unknown asteroids,
but not as
a, "...real asteroid threat ..."
4) Furthermore, Vadim Simonenko of Russia's Federal Nuclear
Centre at
Snezhinsk (Chelyabinsk-70) said, " . . technology would be
able to cope with
any danger by finding the hazardous object in space and by
adopting measures
able to prevent its impact with Earth." However, since we
currently don't
know how many asteroids pose a potential threat to the Earth, and
since
comets can progressively change their orbits by the jet action of
their
warming gas, the mathematics currently available to determine
their orbits
is a chaotic estimate at best. Moreover, how would Vadim
Simonenko handle a
comet like Shoemaker-Levy 9 if it were on a collision course with
the Earth?
5) Finally, Vadim Simonenko expresses his belief by saying,
"But global
catastrophes occurred only once every 100,000 to one million
years, with
consequences ranging from degradation of the human race to its
total
elimination, . . ." However, the scientific community only
recently deduced
that the 1908 Tunguska explosion resulted from as asteroid impact
and
scientists were on that sight almost immediately. Furthermore,
only in that
last 30 years has the credibility of global catastrophes such as
asteroid/comet impacts and massive volcanic eruptions been
accepted in the
scientific community as worthwhile theories for ecosystem
changes.
Therefore, I find it rather presumptuous to assign credibility to
prehistoric data that at best only approximated fractionally what
may have
actually occurred. Furthermore, when was the Earth's last great
asteroid
collision? I don't think Vadim Simonenko or anyone has the data
to enable
them to forecast an asteroid or comet Earth collision with any
certenty. In
fact because of the mathematical concept of chaos, even rainy
weather
forecasting is imperfect. All that is certain is that it will
happen.
I would welcome any explanations for the Russian ideas and
projections on
asteroid impacts that could clear up my questions on their
rational.
Sincerely,
Worth F. Crouch
(Talako)
=================
(9) EROS' DENSITY & THE LESSONS FOR PLANETARY DEFENSE
From Mark Sonter <sonter@camtech.net.au>
Dear Benny,
Following on from Andrew Yee's posting of the report by McKie:
NEAR data now appears to suggest that Eros' density is "too
low", implying
macroscopic or microscopic voids, a highly porous body. This was
found also
with Mathilde.
A highly porous body will not be so easily deflected by an
explosion, the
experts tell us.
This means that deflection by an emplaced propulsion system that
uses
reaction mass mined from the body becomes the method of choice:
this is
technology relevant to space mining, accessing the resources of
the
asteroids for humanity's use. It implies we should be researching
how to
mine asteroidal regolith, and cometary mantle material, and solar
powered
steamrockets, and steam powered 'regolith rockets', and mass
drivers.
Mark Sonter
==========
(10) HOLST AND THE PLANETS
From Don Barrett <barrett1@lvcm.com
>
Dear Phil Plait:
I know Kent's MO, and the actual story regarding Holst and Pluto
is
incorrect. In fact, Holst started working on
Pluto. Partially completed
he suffered a stroke and attempted to do what Delius did,
that is dictate
the remainder to one of his students. Holst found
this unsatisfactory and
decided not to finish. The quote attributed to him
came from somewhere but
not Gustav. This information comes from rather good
authority. While a
student at Oxford, I studied under Holst's best friend, Sir
Adrian Boult.
In addition, I was fortunate enough to meet Imogen Holst, the
composer's
wife. The info re Pluto came from these two sources.
Kent is something of
a showman, and I take real exception to his interpretation of the
work,
which he is claiming as his own (as a conductor). Adrian
Boult conducted
the first performance with the composer present. I have to
believe his
interpretation to be the most authentic. Kent takes major
liberties with
tempo especially in Uranus and Jupiter. As far as I'm
concerned, my Pluto
is as good as his and who is to say what Holst would have written
had he be
able to complete the work. Incidentally, the remarks about Mahler
are also
incorrect. The tenth symphony was never
finished, nor was the last
movement even sketched. The symphony was
completed under a commission by
the New York Philharmonic by Derek Cook using what he
believed to be
Mahlerian themes.
If the science world wishes to declare Pluto a non-planet then I
think the
same case can be made for Jupiter and Saturn. After all,
they are really
failed stars without sufficient mass to initiate nuclear fusion.
Don Barrett is a producer-director working in High Definition
Television/Film Production. He has recently produced a long
form music
video documentary entitled, "Patrick Stewart narrates 'The
Planets"
(http://www.don-barrett.com).
========
(11) PLUTO ROMANTICS, AGAIN
From Joshua Kitchener <staff@dot-comet.com>
Dear Benny,
Mr. Atkinson affirms in his letter to you that he is concerned
about "...the
opinions of non-astronomers in all this, the men and women and
children 'in
the street'."
And that deplanetizing Pluto is tantamount: "not just (to)
re-writing
science textbooks, it's re-writing history, and it's re-writing
it with
cold, perhaps even arrogant disregard for the image
non-astronomers have of
Pluto."
Most shockingly, Mr Atkinson also urges that scientists to care
not to
offend "...the people who buy astronomy books, watch
Discovery Channel
programs - and buy planetarium tickets".
These statements epitomize the position of the Pluto Romantics,
who seem to
have mistaken Astronomy for Astrology.
Ever notice how religious zealots try to convert others to their
faith? This
compulsion is usually a reflection of their own lack of faith in
what they
are preaching. I'm always a little suspicious of astronomy clubs
that
actively "reach out" for new members.
Mr. Atkinson, please do not worry that the truth about Pluto will
render
Astronomy unattractive to the layperson. There have always been
people
interested in Astronomy, and there always will be.
Quite sincerely,
Joshua Kitchener
Publisher, NearEarth.net Magazine
http://NearEarth.net
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