CCNet 73/2002 - 25 June 2002
"Asteroid 2002NM, as it was retrospectively named, is the sixth
recorded object to have passed closer to Earth than the moon - and
much the largest so far. The episode highlights the fact that we are
under constant bombardment from space. It is likely to increase the
pressure on politicians to fund a more systematic search of the solar system
for the asteroids and comets - known collectively as "near-Earth
objects" - that pose a serious threat to life on our planet."
--Clive Cookson, Financial Times, 22 June 2002
"Questions have been raised as to whether our ability to detect
asteroids as they hurtle near the Earth is undermined by
underfunding. Some places on Earth, specifically in the Southern
hemisphere, might not have the observation labs and technology needed to
keep on top of asteroids.... Morrison says that more funding above
NASA's current $3 million Near- Earth Object survey budget would be nice,
but that it won't do much more to protect the Earth from asteroids.
Instead, the extra money would speed up things that don't really need to
be sped up, he says."
--Lindsey Arent, Tech Live, 24 June 2002
(1) VULCAN IN THE TWILIGHT ZONE
BBC Online News, 24 June 2002
(2) UNDER FIRE FROM COSMIC FALL-OUT
Financial Times, 22 June 2002
(3) OH HAPPY DAY: DR PANGLOSS EXPLAINS WHY THERE IS NO NEED FOR MORE NEO
SEARCHES OR TELESCOPES
Tech Live, 24 June 2002
(4) JPL TO ASSIST ON CONTOUR MISSION
Ron Baalke <firstname.lastname@example.org>
Tom Soper <email@example.com>
(6) ON IMPACT HAZARD AND PLANETARY DEFENSE
Drake A. Mitchell <firstname.lastname@example.org>
(7) AND FINALLY: THINKING ROBOT ESCAPE ATTEMPT THWARTED
Ananova, 20 June 2002
(1) VULCAN IN THE TWILIGHT ZONE
>From the BBC Online News, 24 June 2002
By Dr David Whitehouse
BBC News Online science editor
Two US astronomers have been looking for a suspected belt of asteroids close
to the Sun by making observations from the back seat of an F-18 jet.
Dan Durda and Alan Stern, from the Southwest Research Institute (SwRI) in
Boulder, Colorado, are looking for the Vulcanoids, a ring of debris lying
between Mercury and our star.
First postulated over a century ago, the Vulcanoids are thought to range in
size from one to 25 kilometres. Finding them would change our understanding
of the innermost region of our Solar System.
If they do exist, it is possible they could still contain fragments of the
earliest materials that formed next to our star when it was newborn.
"Most comprehensive search"
Durda and Stern are flying at a height of 15 kilometres (49,000 feet) to get
the observing conditions that will best enable them to prove the belt's
There is a short period of opportunity to catch the space rocks
Some theories suggest that a small number of kilometre-sized and larger
Vulcanoids could have survived in the inner Solar System, inside the orbit
of the planet Mercury, until now.
"Our Vulcanoids search programme, conducted from an altitude of 49,000 feet
over the Mojave Desert, gave us a view of the twilight sky near the Sun that
is far darker and clearer than can be obtained from the ground," says Dr
"This is the most comprehensive, constraining search yet conducted for these
objects," adds Dr Stern, director of the SwRI Space Studies Department.
The camera was designed with the shuttle in mind
Astronomers have conducted ground-based searches for the Vulcanoids before,
during total solar eclipses, and during the twilight period after sunset
just before the Vulcanoids themselves would set.
But to date, the asteroids have not been seen. Observations have only placed
upper limits on how many might exist.
The camera used in the latest search was originally conceived for the space
shuttle. It is trained on the region of space close to the Sun after the
star has dipped below the Earth's horizon. The camera grabs twilight images
at a rate of 60 frames a second.
The researchers are currently analysing their data. They hope to know if the
Vulcanoids exist in a month or two.
Copyright 2002, BBC
(2) UNDER FIRE FROM COSMIC FALL-OUT
>From Financial Times, 22 June 2002
THE ASTEROID THAT NARROWLY MISSED THE EARTH HIGHLIGHTS A LITTLE-KNOWN THREAT
TO HUMAN EXISTENCE, SAYS CLIVE COOKSON
Earth had a narrow escape last week. A gigantic rock the size of a football
pitch whizzed past our planet at a distance of just 120,000km - an
astronomical hair's breadth.
If the asteroid had hit a populated region, there would have been mass
casualties and destruction as it exploded in the atmosphere with the force
of a 10-megaton atomic bomb. A rock about half its size flattened 2,000 sq
km of forest in the Tunguska region of Siberia in 1908.
There was no advance warning that an asteroid was coming our way. Indeed
astronomers knew nothing until early this week, three days after the fly-by,
when the Linear Laboratory Near Earth Asteroid Search (Linear) project in
New Mexico spotted it as a faint object racing away from Earth at 10km per
Asteroid 2002NM, as it was retrospectively named, is the sixth recorded
object to have passed closer to Earth than the moon - and much the largest
The episode highlights the fact that we are under constant bombardment from
space. It is likely to increase the pressure on politicians to fund a more
systematic search of the solar system for the asteroids and comets - known
collectively as "near-Earth objects" - that pose a serious threat to life on
Until recently most people would have dismissed such fears as science
fiction or the stuff of Hollywood horror films. But research over the past
decade has shown that space debris played a key role in terrestrial
First, scientists proved beyond reasonable doubt that the dinosaurs were
wiped out 65m years ago by a monster asteroid 10km wide. Then they linked
other mass extinctions, such as the previously unexplained Great Dying that
wiped out 90 per cent of living species 250m years ago, to cosmic impacts.
Estimates based on the pattern of craters on the moon suggest that an
asteroid or comet more than 5km in diameter hits Earth about once every 10m
years. Its deadliest effect is not the explosion - though this would be
equivalent to a million 10-megaton bombs - but the pollution thrown into the
atmosphere from the impact crater. Billions of tons of dust, sulphur and
carbon dioxide would change the climate profoundly.
In one sense, we owe our existence to such impacts, which smoothed the
evolutionary path to mammals and eventually humans by eliminating competing
groups of animals. But now that we are here, we do not want to be removed in
turn by the next big rock to hit Earth.
Although the probability of an impact big enough to kill all 6bn people on
Earth is tiny, a smaller impact could still have a devastating effect on
modern civilisation. The latest estimates show that objects 1km in diameter
- big enough to kill hundreds of millions of people - hit once every 100,000
Many people became aware of the risk in 1994 when telescopes recorded the
spectacular collision between Comet Shoemaker-Levy and our sister planet
Jupiter. At the same time two US scientists, Clark Chapman and David
Morrison, came up with a striking hazard assessment: an average American is
as likely to die as a result of a collision with an asteroid or comet as he
or she is to die in an aircraft crash. In each case the lifetime probability
is about one in 20,000.
Disaster films such as Deep Impact have also raised popular consciousness
about the issue. Even so, politicians still find it hard to appreciate the
real cosmic hazard because there has been no fatal impact during recorded
history, says Duncan Steel, an expert on near-Earth objects at Salford
If they did realise the size of the threat, governments would commit more
funds to doing something about it, Mr Steel says. It would have a better
cost-benefit analysis than any other public spending project.
Several observatories around the world have been mapping near-Earth objects
for several years, so as to identify ones that might hit us. Astronomers
believe they have found about half of the 1,100 or so objects that are
larger than 1km diameter and potentially cross Earth's orbit. None poses a
significant threat over the next century.
A more systematic international search called Spaceguard, led by the US, is
under way. It is well beyond the capability of today's telescopes to find
all potentially threatening objects but the next generation of observatories
will be able to do better.
One candidate for finding near-Earth objects is Vista, a 4-metre telescope
that will be built over the next four years in the Chilean Andes by a
British university consortium at a cost of more than Pounds 25m. Jim Emerson
of Queen Mary, University of London, the Vista project leader, says further
funding would be needed to adapt the telescope so that it could search
usefully for asteroids in addition to its other work. A more powerful but
more distant possibility is the 6-to-8-metre Large-aperture Synoptic Survey
Telescope being planned in the US. Its promoters say it could identify every
object down to 300 metres in diameter.
What would happen if astronomers found a large asteroid heading for Earth?
The best way to head it off would be through a nuclear explosion, says Mr
Steele, though the planning would have to be meticulous to make sure that
the blast deflected it to a safe path, rather than breaking it into several
rocks all heading for Earth.
A gentler alternative, given several decades' warning, would be to deflect
the asteroid by altering its surface - in effect painting it black or white
- to change the amount of sunlight it reflects.
But if we had a few days' warning only, we could do nothing but panic or
pray. "Then it might be better not to know," says Prof Emerson. "If I'm
going to have a heart attack next week, I'd rather not be warned about it."
Copyright © 2002: Financial Times Group
(3) OH HAPPY DAY: DR PANGLOSS EXPLAINS WHY THERE IS NO NEED FOR MORE NEO
SEARCHES OR TELESCOPES
>From Tech Live, 24 June 2002
Asteroid Hunting Challenge: Why scientists missed the most recent cosmic
By Lindsey Arent, Tech Live
June 24, 2002
An asteroid hurtles through the solar system, on a collision course with
Earth, only to be deflected from its deadly orbit just in the nick of time.
It's the stuff of movies such as "Deep Impact" and "Armageddon." But as
"Tech Live" reports tonight, truth may be more frightening than fiction.
"The Earth orbits the sun within a small asteroid belt. We're part of a
cosmic shooting gallery and we know the Earth has been hit over time many,
many, times," NASA scientist and asteroid-watcher David Morrison said. "If
we could see all the craters that've been made on the Earth, it would be as
many craters as there are on the moon."
Case in point: An asteroid the size of a football field passed extremely
close to Earth just last week, missing us by a mere 75,000 miles. That's one
of the closest cosmic collisions ever recorded.
Despite the close call (the distance was about one-third the distance to the
moon) the asteroid went undetected by astronomers until days later. How
could we have missed such a close call?
In many cases, asteroids are fairly small objects, and if they measure less
than a mile in diameter, they can be faint and tough to detect unless
they're close to the Earth, Dr. Don Yeomans of NASA's Near-Earth Object
Program says. Many asteroids also come from the direction of the sun and are
only visible in the nighttime sky.
"Doesn't really matter," Morrison said. "There are no extra points for
getting it on the way in. We just want to find them, catalog them, project
their orbit, and make sure they're not a threat to us."
Is sooner better?
Questions have been raised as to whether our ability to detect asteroids as
they hurtle near the Earth is undermined by underfunding. Some places on
Earth, specifically in the Southern hemisphere, might not have the
observation labs and technology needed to keep on top of asteroids.
In fact, Congress has mandated that NASA hunt down and track 90 percent of
near-Earth objects with a diameter of a mile or more by 2008.
Morrison says that more funding above NASA's current $3 million Near-Earth
Object survey budget would be nice, but that it won't do much more to
protect the Earth from asteroids. Instead, the extra money would speed up
things that don't really need to be sped up, he says.
"If we had more telescopes, we could accomplish the survey faster, or we
could go to fainter objects. If we had telescopes in the Southern
hemisphere, that would be a special advantage," he said. "But it's just a
matter of speeding it up. We'll get there even with the telescopes we have."
The same goes for the issue of high-concept technologies, such as putting a
telescope on the moon or in orbit around Mercury. These are great ideas, but
some critics have asked, isn't the money better spent on homeland defense or
on other major threats?
"The real question," Morrison said, "is how important is this hazard vs.
Copyright © 2002 TechTV Inc. All rights reserved.
(4) JPL TO ASSIST ON CONTOUR MISSION
>From Ron Baalke <email@example.com>
JPL To Assist On Comet Mission
June 21, 2002
Contour prepares for July 1 launch
Set to visit and study at least two comets, NASA's Comet Nucleus Tour
(Contour) should provide the first detailed look at the differences between
these primitive building blocks of the solar system, and answer questions
about how comets act and evolve. The mission is being prepared for a July 1
launch from Kennedy Space Center.
JPL will provide navigation and Deep Space Network support for the mission,
and JPL astronomer Dr. Don Yeomans, manager of NASA's Near Earth Objects
Program Office, is a Contour science team
Contour is scheduled to lift off on a three-stage Boeing Delta II expendable
launch vehicle during a 25-day launch window that opens July 1 at 2:56 a.m.
Eastern time. The spacecraft will orbit Earth until Aug. 15, when it should
fire its main engine and enter a comet-chasing orbit around the sun.
Contour's flexible four-year mission plan includes encounters with comets
Encke, Nov. 12, 2003, and Schwassmann-Wachmann 3, June 19, 2006. Contour
will examine each comet's "heart," or nucleus, which scientists believe is a
chunk of ice and rock, often just a few kilometers across and hidden from
Earth-based telescopes beneath a dusty atmosphere and long tail.
"The Contour mission will be NASA's second mission dedicated solely to
exploring these largely unknown members of our solar system," said Dr.
Colleen Hartman, director of the Solar System Exploration Division at NASA
Headquarters in Washington. "Contour joins our other operating mission,
Stardust, which is on its way to bring a sample of a comet back to Earth,
and Deep Impact will launch next year. These missions all help us find
answers to the fundamental questions of how our planet may have formed and
evolved, and how life may have begun on Earth and perhaps elsewhere in the
Comets are "the remnants of the outer solar system formation process,"
Yeomans said in a prelaunch briefing. The instruments on Contour, he added,
will determine the chemical composition of the comet - helping in turn to
determine whether a comet might have brought much of the Earth's oceans and
its atmosphere, as well as carbon-based molecules, to the Earth's surface.
Yeomans said the "genius" of the Contour mission design is that "we're not
chasing comets around the solar system; we're using Earth swingbys to allow
them to come to us." The encounters are taking place very close to Earth
(less than 50 million kilometers or 31 million miles), which, he said,
"makes communications easy, but it also allows professional, ground-based
astronomers, as well as amateur astronomers and the public, to participate
in a very meaningful way." The comets will be bright enough to be seen with
binoculars about the same time as Contour is looking at the comet's nucleus,
Members of the JPL navigation team include Tony Taylor, Bobby Williams,
George Lewis, Cliff Helfrich, Eric Carranza, Don Han, Ramachand Bhat and
The eight-sided, solar-powered craft will fly as close as 100 kilometers (62
miles) to each nucleus, at top speeds that could cover the 56 kilometers
between Washington and Baltimore in two seconds. A five-layer dust shield of
heavey Nextel and Kevlar fabric protects the compact probe from the comet
dust and debris.
"Comets are the solar system's smallest bodies, but among its biggest
mysteries," said Dr. Joseph Veverka, Contour's principal investigator from
Cornell University, Ithaca, N.Y. "We believe they hold the most primitive
materials in the solar system and that they played a role in shaping some of
the planets, but we really have more ideas about comets than facts. Contour
will change that by coming closer to a comet nucleus than any spacecraft
ever has before and gathering detailed, comparative data on these dynamic
Contour's four scientific instruments will take pictures and measure the
chemical makeup of the nuclei while analyzing the surrounding gases and
dust. Its main camera, the Contour Remote Imager/Spectrograph, will snap
high-resolution digital images showing car-sized rocks and other features on
the nucleus as small as 4 meters (about 13 feet) across. The camera will
also search for chemical "fingerprints" on the surface, which would provide
the first hard evidence of comet nuclei composition.
Encke has been seen from Earth more than any other comet; it's an "old" body
that gives off relatively little gas and dust but remains more active than
scientists expect for a comet that has passed close to the sun thousands of
times. Schwassmann-Wachmann 3, on the other hand, was discovered just 70
years ago and recently split into several pieces, intriguing scientists with
hopes that Contour might see fresh, unaltered surfaces and materials from
inside the comet.
Contour is the sixth mission in NASA's Discovery Program of lower lost,
scientifically focused exploration projects. Johns Hopkins University's
Applied Physics Laboratory manages the mission, and also built the
spacecraft and its two cameras. NASA's Goddard Space Flight Center provided
Contour's neutral gas/ion mass spectrometer and von Hoerner & Sulger, GmbH,
Schwetzingen, Germany, built the dust analyzer.
For more information, visit http://www.contour2002.org.
* LETTERS TO THE MODERATOR *
>From Tom Soper <firstname.lastname@example.org>
Good afternoon Benny:
I am very pleased to see that, at this writing, the community has been able
to "get on it" and has made 156 observations of 2002LY45. You may recall
that, last year, I was a minor player in the uproar over the manner in which
information regarding 2001PM9 was disseminated. That is, the alert I sent
out resulted in debate about whether NeoDys ought to be publishing
preliminary information on a public web-site, and exactly how preliminary
information was being distributed so as to ensure the maximum opportunity to
observe potentially hazardous bodies?
I attempted at that time to create pressure on the scientific and political
apparatus, by way of the media. For my troubles (and perhaps because of my
somewhat "colourful" (I say accurate) descriptions of the effects of an
impact by an Asteroid of this size) I was characterized as all things from
"Chicken Little" to "Crusader".
As it turned out, there were enough observations made to eliminate 2001PM9
as a threat. So, in a way, I ended up with egg on my face on that one.
But, I am tempted to think, maybe not.
Since that time, NASA has launched SENTRY and has its own Impact Risks page
on the Internet. NeoDys has continued its fine work, and did not cave in to
the pressure to bury preliminary results. And given the fact that your
colleagues have amassed nearly 160 Observations on 2002LY45 (an object of
even greater destructive potential given its size and relative velocity) I
have to assume that improvements have been made in the way the word gets out
to those able to make the necessary observations. By my calculation, the
overall average number of observations made on the other 37 Asteroids
currently identified as potential impactors is a mere 26! So this is a
mammoth improvement, and everybody involved deserves congratulations.
Interesting too, is the fact that CLOMON2 (based on 156) and SENTRY (based
on 150) at this point are producing almost identical solutions for 2002LY45,
as to date and time of possible impacts.
A Palermo Scale rating of -.47 is by far the highest I have ever seen. I do
remain stymied by the lack of media attention "real potential impacts" get,
while "real actual misses" get front page headlines (like 2002MN). Well, I
guess the only kind of bad publicity is no publicity at all - and we need
all we can get to get the dollars and facilities needed to accelerate the
pace of this work.
All the best,
(6) ON IMPACT HAZARD AND PLANETARY DEFENSE
>From Drake A. Mitchell <email@example.com>
Please forgive me for pulling a Kruschev and pounding a shoe on the podium,
but if Buckminster Fuller's decades-old cautionary thesis is to be heeded at
all , then we have no time to spare. None. Whatsoever. Period.
The alarming slippage of time becomes obvious to anyone engaged in serious
work or otherwise aware of its large consequences. In our case, with the
solstice now past and Summer in full swing, we are barely two months away
from the first of at least two possibly supreme conferences in our NEO
community. I am sure I am not the only one whose backlog of work continues
to grow at least geometrically. Therefore I can no longer in good conscience
remain silent, without at least offering a summary of issues and an
opportunity for any "trajectory correction maneuovres" that may be
The Excalibur-II (X2) proposal  seems to be alive and gaining momentum.
At least one practical constraint concerns telemetry throughput, as the
existing DSN infrastructure is already expecting an imminent signals
"traffic jam"; new antennae and laser methods promise tenuous relief .
Also encouraging is the increasing support for small satellite technology
and the cataloging of smaller NEOs . Recent discussion on the SSI List
has also proposed one-shot "coffee-can" sized spacecraft that could approach
the many nearby NEOs for close-up fly-by imaging and/or small impact events
that could yield plumes amenable to ground-based spectrometry.
Lingering doubts remain, however, which is hard to fathom when the new
Department of Homeland Security would have an initial annual budget more
than twice NASA's at ~$38B without even FOIA and Whistleblower protections,
and given that Planetary Defense would benefit from methods alternate to
nuclear detonation: as has been known for years, we can turn the enemy
against itself by using the much more available smaller NEOs against the
much more lethal ones. Additionally, X2 could conceivably be immune to all
seven of the blind spots that afflict ground-based optical telescopes; the
comet-detection bonus is also drawing substantial support. To his credit,
Kieffer-Olsen also points out the further bonus possibility of sampling the
coplanar Mars-toroidal region, albeit with an NMO/NEO detection size
threshold ratio >>1; implications are discussed below.
An area that apparently still has gaping holes requiring considerable
further research concerns the complete distribution of collision
probabilities across the entire PHA population, i.e. which subgroups have
greatest likelihood, e.g. by the plethoric plague of N-body resonances N=3
to ~6 (various permutations of massive bodies), orbital energy, low
relative-velocity encounters, gravitational focusing effects, Lyapunov
indicators, problematic coplanar tangent encounters, fractal dimensionality
 etc. Milani et al highlight the non-Gaussian distributions of
astrometric errors, and the urgency of nonresonant returns and multiple
returns, as well as the discovery of pathologically large keyholes for NEOs
on particular "interrupted" resonant returns, in an overview of linear and
nonlinear analytical methods in the upcoming Asteroids III tome . True,
George Friedman's BNS theory may offer considerable firepower for such
analytical challenges, but given that all PHAs and smaller could be
catalogued in a mere six years, is it really worth risking further delay? I
think not, and economic analyses agree, even with the consequence that
ground-based astronomers and "virtual observatories"  would at long last
experience massive budget growth for crucial post-detection NEO
There have been requests for clarification concerning the MOID parameter and
X2; here goes. Collision requires coincidence in both space and time. The
key spatial parameter and hazard indicator discussed so far is the MOID:
"This distance, which is known as the Minimum Orbital Intersection Distance
(MOID), is equivalent to the minimum separation between the osculating
ellipses, without regard to the location of the objects on their orbits".
Note that several local minima for MOID are possible with multiple nodes of
intersection: two, or more, depending on the geometry of the ellipses. Note
also that there are NEOs with low MOIDs with the Earth and also at the same
time with other massive bodies ; a diagrammatic and analytical
introduction to the MOID is recently available .
The additional criteria for a collision is that, given a low enough MOID,
there is also proximity in time: the Earth and the NEO must not only cross
paths, but they must also do so at the same time. Thus NEOs in "presonances"
never cross paths at the right times for collision while they are in such
resonances, and NEOs caught in the permanent dynamic web of hazardous
resonances cross paths with the Earth in complicated time intervals.
Determining these path-crossing appointments with destiny, and their
corollary collision probabilities, is highly nontrivial. However, the simple
starting point for identifying the objects of notoriety is the MOID, the
path-crossing indicator. Incidentally, helpful analogies can be made with
space debris that may be potentially hazardous to the ISS, Shuttle, and many
other assets in Earth orbit, and even with the recent discussion (Lou Dobbs,
CNN's Moneyline) regarding a better definition for the "war on terror" by
focusing attention first on the population of "Islamist" radicals in
general, and then second on the militant Islamist radicals in particular.
We can define another parameter, which implies a combined spatiotemporal
proximity, the Minimum Geocentric Distance (MGD; apologies to the Miller
Brewing Company). Objects with a low quantity of MGD in the present will
necessarily also have a low MOID, and this may be as good a reason as any to
drink a fine beer. However, the converse is not generally true: NEOs with a
low MOID now are the very PHAs that may suddenly, perhaps too suddenly,
become low enough in MGD to present a hazard. While an exhaustive analysis
of MGD is beyond our scope and taste here, suffice it to say that as it
depends on the osculating distance to an NEO, that a) the MGD is never less
than the MOID, and b) unlike the MOID, the MGD exhibits a much greater
variability in short periods of time, i.e. units of orbital periods. (I'm
reluctant to say that more MGD for the PHAs would solve all our problems,
but driving NEOs under our influence would have prudent advantages; see
below). A specific distribution of MGD for the PHAs is illustrated by a
graph I have posted on the web .
The data for this graph was computed and processed in a Sunday afternoon and
a weeknight using an N-body integrator on a Pentium PC with Windows98. A
simple non-debiased system of 438 known PHAs was integrated for the period
2001-2007, and the MGDs and toroidal traversals extracted, allowing
approximate comparative assessments of X2 with geocentric deployments of
space-based detection platforms. The graph shows the cumulative percentage
of PHAs that could be detected traversing within increasingly larger spheres
around the Earth (orbiting with the Earth around the sun). The graph is in
Log-Log format to highlight the data at lower values.
At the high end, we can see that all the PHAs (and much more) would be
detected if we could detect every traversal through a ~2.05 AU radius "Globe
of Danger" about the Earth, which of course grossly and easily envelops the
much smaller critical volume of the toroidal "Donut of Danger". At the low
end, at 0.01 AU, about the distance of L1 towards the Sun, less than 1% of
the PHAs could be detected crossing the corresponding spherical volume with
this radius. Thus Rather's ARGUS proposal at 1995's LLNL PDW  could
detect among the more interesting ~1%'s of the PHAs, those with both MGD and
MOID <0.01 AU during this period. However, ARGUS would not by this
geocentric estimate detect either a) the remaining ~95% of the ~20% of all
PHAs, those with MOID<0.01, that did not happen to have MGD<0.01 during this
short period, or b) the remaining ~80% of all PHAs with 0.01<MOID<0.05 AU.
These undetected PHAs could unfortunately demonstrate MGD<0.01 and MGD<0.05,
respectively, virtually anytime thereafter. Note that for orbital
forecasting "the close approach threshold distance used for the Earth is
typically ~0.1-0.2 AU" [5 p.15], which scales by mass in any of the schemes
of close approaches involving Mercury, Venus, the Moon, Mars, and/or
Jupiter. Thus, "to lock in maximum warning times"  for the PHAs, it pays
to go after the entire PHA population, especially since this can be done
within a mere 6 years by observing the entire toroidal volume, not just the
segment including the Earth.
Similarly for spheres at larger radii. Within 0.05 AU, also the radius of
the Donut of Danger, less than 10% of the PHAs could be detected in the same
period. Within 0.23 AU, or a sphere about equal to the entire volume of the
Donut of Danger, only ~45% could be detected. The median is at ~0.28 AU, or
about the distance of Venus at its closest approach to Earth. However, the
medians for some subpopulations would be at greater radii: 50% of PHAs with
upper-medium eccentricity 0.6 < e < 0.8 detectable within ~0.37 AU (230%
greater volume), and 50% of PHAs with orbital periods greater than 3 years
within 0.44 AU (388% greater volume). At 1 AU, about the distance of the
Earth's L4 and L5 points, ~88% could be detected. This is finally high
enough to have an important consequence: it appears that it would be quite
prudent to consider relocating two older space-based detection platforms to
L4 and L5, and to supplement this relay capacity with a third at L3, behind
the Sun. Thus we could have a robust three-pronged attack, using 1) the many
ground-based assets, 2) three large space-based Lagrangian assets, and 3) a
fleet of much smaller space-based toroidal assets.
"Older" space-based detection platforms that are candidates for relocation
include the Keyhole-class telescopes  and the DSP satellites . Three
of either class would require modifications, and the former possibly
multiple Centaur-like upper-stage boosters. Crude estimates using JSC's AMCM
 assuming Block 5, high difficulty, 30,000 lbs/5,000 lbs payloads, and
single launches in 2003 yield costs of ~$2.30B and ~$712M, respectively.
Lead times and simulated efficiencies are not the only challenges; Russian
and other assets should also be considered. Of course these costs are low
enough that this may already have been done years ago, in which case this
seems like a fine year for declassification. Furthermore, basing the
refurbished Hubble at L4 or L5 could have substantial benefits just for its
existing user community, including several pointing advantages deriving from
the release from the shackles of 90-min Low Earth Orbits, even if this bird
no longer "flaps its wings" like it used to. These costs may seem expensive
compared to historical NEO expenditures, particularly for ground-based
efforts, but it is also easily demonstrable that we have been painfully
underspending on the NEO hazard for a decade; one great benefit of these
early efforts is that cost is now less of an issue than payoff.
Assuming a small satellite covering a segment of the Donut of Danger 0.1 AU
(2 x 0.05) in width by observing a surrounding sphere with radius 0.07, at
least 126 would be required for overlapping coverage of the entire toroid
along the Earth's orbit. The one observing the Earth would detect the lion's
share of PHAs, ~10%, but note that the entire ring of satellite "buoys"
could slowly rotate within the Earth's orbit without significant detection
penalty, thereby possibly providing the minimum delta-V requirements. A
decent cost-estimate might require the use of the Aerospace Corporation's
SSCM99 . However, if we take NESS as a reasonable upper limit, and a
per-unit cost near $2.0M, the fleet might cost less than $252M to build.
What is not yet clear is the minimum size detection threshold; a reasonable
non-IR limit seems to be ~110m, plenty low enough to justify immediate
deployment. Pushing the detection limit down further using infra-red Si:Ga
technology may or may not be immediately cost-effective, in which case this
capability could be deployed in a second-generation fleet that also benefits
from a more fully upgraded DSN and relieves the first fleet for
reconnaissance tasking to selected NEOs.
Clearly the satellite fleet seems a much better value. Certainly X2 still
requires further verification; my graph can be verified by various groups in
less than a day, and at least one additional simulation involves the
turnover in the PHA population over the current century. However, the stakes
are assuring the safety of civilization, and having several fronts of attack
is the epitome of a robust strategy. Indeed, NEO-enabling the MESSENGER
mission still seems prudent. Who would like to be guilty of missing the
detection of a large NEO impactor that just happens to have a bad date with
Earth within the next 25 years, when this could be prevented in six? The
stakes are too high, the odds are just not low enough, and the economics are
on our side.
Several other projects are also making progress. Readers may recall
January's "dust-up" regarding Pope's paper, which concerned the sensitivity
of estimates of the long-term NEO threat, and thus annualized estimates of
economic damage, to the uncertain threshold for catastrophic global effects.
I've looked into extending John Lewis' simulation to include global effects,
for such a sensitivity analysis, by starting with a statistical model of the
geological layer. I found Laske et al's CRUST 2.0 model of the Earth 
with 2x2/1x1 degree 7-layer cells (ice +/- 250m, water, soft/hard sediments
+/- 1km, upper/middle/lower crusts +/- 5km), which gives a nice start
towards modeling the impact cratering of 500m+ NEOs. A next step might be
supplementing this dataset with variations in sedimentary mineral
composition, e.g. sulfur.
The next project concerns an in-depth review of the scientific literature on
the SL9 impact on Jupiter, a story that seems to continually offer new
dimensions of amazement. I expect to have a long essay on the subject
completed mid-Summer. What is important to say about the subject now is that
the event was an unbelievably miraculous gift; the continuing stream of data
includes psychological insights, incredible orbital dynamics and dozens of
impact effects, and the implications are many, but perhaps the most
strategic is the paramount importance of empirical methods in science. The
bottom line is that we can benefit hugely from a few more such
non-terrestrial live impact events, as global effects thresholds have been
an outstanding problem.
This has been the subject of a project I started in February and expect to
complete before September. The new paradigm I recounted in April provides
the means: without using nuclear detonation methods, new astrodynamic
techniques now allow us to empirically investigate well within our lifetimes
the poorly understood global effects thresholds of NEOs, by arranging
similar, highly specified events on other planetary bodies. I have already
identified several dozen candidate NMOs for modeling the orbital
modifications necessary to arrange impacts on Mars, which of course is
already the focus of substantial and increasing instrumention infrastructure
and research. I review the many variables regarding the impactor and
conditions of impact, with the goal of identifying the smallest set of
customized impacts that would yield the best data for understanding the
global effects of NEO impacts on Earth. Perhaps the most promising
propulsion options are nuclear-powered mass-drivers, and plasma engines (see
below). Such a program would overlap somewhat with "terraforming", and even
Buzz Aldrin's space tourist agenda - how much would you be willing to pay to
witness a multi-gigaton impact event on Mars?
It would also be worth considering custom impact events on Mercury (much
hotter than the Moon, but allowing us to calibrate both sets of craters),
Venus (with a much thicker, hotter, and windier atmosphere), Jupiter (to
calibrate SL9), Io (to study volcanic and tectonic effects), Europa (a small
tsunami laboratory would also reveal ice thickness and enable subsurface
investigations), Saturn (to investigate the Great White Spots), and Titan
(another atmosphere, and possibly another ocean, as we will soon find out).
A related story concerns "death by comet cyanide", which is an issue on Mars
or Venus, as at Jupiter, but not a first-order effect on oxygen-rich Earth.
John Lewis raises the concern that substantial data reduction challenges
would arise, but I call this a happy problem. I expect more difficult
challenges in the debates arena, and so have prepared first-strike rebuttals
for major political constituencies that could be sharper still; fortunately
it also appears that a further quantification weighting the Titanic
comparative risk model is forthcoming. "Let the year-long Octoberfests
By the way, another outstanding problem in the field concerns possible
periodicities in the NEO flux, and it occured to me that someone should
investigate the possibility that the growing field of Stochastic Resonance
may have applications to our complex dynamical system of NEOs:
Furthermore, here are two important references that seem to have been missed
on CCNet. Some notes are finally available concerning Project B612, the
"Deflecting Asteroids" workshop at NASA/Johnson, 20Oct01:
Also, ~70 pages of abstracts are available from 09Feb02's Rubey Colloquium
at UCLA: http://www.ess.ucla.edu/rubey/abstract.pdf
Incidentally, Texas Tech's Sankar Chatterjee was kind enough to provide an
update on the suspected Shiva astrobleme. This could be the topic of yet
another essay, as more positive evidence has accumulated, but he is
scheduled to present a major paper on the subject in Cape Town in July.
Separately, it also appears that an important new edition of a major text on
planetary science will be coming out this year.
There seems to be a concensus that September's conference in metro
Washington, DC will be the most important NEO meeting yet held on our
I propose that optimizing the effects of this conference should be of
paramount interest to all of us, and submit that an immediate dialogue on
this issue should be a top priority for all CCNet participants. As the U.S.
ship of state seems to be pulling off flying jibes while shooting up a new
mast built from the other rigging under full sail, and even the FBI has
admitted that it needs to import intelligence, is it really too much for us
to expect NASA to consider a threat-focused overhaul? It is high time for a
totally new Federal Advisory Committee Act (FACA) body to take up this
interagency issue; a $20M appropriation over three years would allow our
field to raise needed matching funds and to fully prepare for the long haul,
as it has long deserved.
Finally, even more disturbing to me than this year's episode in Australia,
was a Crossfire show on CNN where a prominent spokesman for American
physicists was unable to say a single positive thing about the Space
Station! Bob Park has written a long series of insightful commentaries over
the years ("What's New"  ), but if he and his many colleagues are unable
to come up with important objectives for the ISS, then the nicest thing I
can say is that I suggest he try querying groups like ProSpace and CCNet. On
a side note, as the Cosmonauts have recently expressed interest in Station
visits by Cindy Crawfords, it seems that I may have had a typo in April: did
I actually mean "babe-sitting"?
I liked your recent MSNBC quote pointing out the paradoxical nature of our
universe - "...we are living in an extremely dangerous universe - which is
at the same time true and not true." However, humanity can only enjoy the
clear benefits of this paradox if we manage to continue to survive its
obscure hazards. There is a hexapocalypse of large NEOs needing to be
discovered; yesterday is not too soon. I salute Moby's new anthem, "No one
can stop us now, 'cause we are all made of stars."
 http://abob.libs.uga.edu/bobk/ccc/cc060702.html (#1)
(7) AND FINALLY: THINKING ROBOT ESCAPE ATTEMPT THWARTED
>From Ananova, 20 June 2002
Scientists running experiments with "living robots" which think for
themselves say they have been amazed to find one escaping from the centre
where it "lives".
The unit, called Gaak, is one of 12 which are taking part in a "survival of
the fittest" test at the Magna science centre in Rotherham, South Yorkshire,
which has been running since March.
Gaak made its bid for freedom after it had been taken out of the arena where
hundreds of visitors watch the machines learning as they do daily battle for
Professor Noel Sharkey said he turned his back on the drone and returned 15
minutes later to find it had forced its way out of the small make-shift
paddock it was being kept in.
He later found it had travelled down an access slope, through the front door
of the centre and was eventually discovered at the main entrance to the car
park when a visitor nearly flattened it with his car.
Prof Sharkey said: "Since the experiment went live in March they have all
learned a significant amount and are becoming more intelligent by the day
but the fact that it had ability to navigate itself out of the building and
along the concrete floor to the gates has surprised us all."
And he added: "But there's no need to worry, as although they can escape
they are perfectly harmless and won't be taking over just yet."
Copyright 2002, Ananova
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