PLEASE NOTE:


*

CCNet DIGEST, 10 March 1999
---------------------------

(1) A THREATENING PRESENCE FROM PLANET REMAINS
    THE IRISH TIMES, 8 March 1999
   http://www.irish-times.com:80/irish-times/paper/1999/0308/hom30.html

(2) HILTON BACK SPACE HOTEL: 'WE ONLY NEED $6 - $12 BILLION'
    BBC News Online
http://news.bbc.co.uk/hi/english/sci/tech/newsid_293000/293366.stm

(3) SNL & JPL PROPOSE $1BILLION INTERSTELLAR EXPLORER
    Scripps Howard News Service
    http://www.bergen.com:80/morenews/spacetug199903098.htm

=====================
(1) A THREATENING PRESENCE FROM PLANET REMAINS

From THE IRISH TIMES, 8 March 1999
http://www.irish-times.com:80/irish-times/paper/1999/0308/hom30.html

From Larry Klaes <lklaes@bbn.com>

Massive building blocks left over after the planets formed still orbit
the sun beyond Neptune, and every 100,000 years or so one wanders
towards us, posing an enormous risk to the Earth. Dick Ahlstrom reports
on efforts to learn more about them.

Astronomers at Queen's University Belfast and Armagh
Observatory are undertaking an international study of a belt of
planetary leftovers, enormous objects up to 800km across
which orbit the sun beyond Neptune.

New "Trans-Neptunian Objects", TNOs, were being discovered every month,
said Dr Alan Fitzsimmons, reader in observational astrophysics at
Queen's, although the first was identified only in September 1992.

The most recent, the 113th, was announced on February 16th, he said,
and his group had discovered eight. He said the objects were found in
what is known as the Kuiper Belt, a band of material in orbit between
30 and 50 astronomical units (AU) from the sun.

An AU is equivalent to the distance of the Earth from the sun, about 93
million miles.

The first astronomer to theorise about their presence was an Irishman
from Streete, Co Westmeath, Kenneth Edgeworth, an accomplished amateur
who published two papers in the 1940s.

These remained virtually unknown but the idea persisted, culminating in
a paper in 1951 by a Dutch astronomer, Gerard Kuiper, whose name now
describes their place in the solar system.

TNOs are remarkably difficult to spot, Dr Fitzsimmons explained,
because of their small size relative to their distance from us and
because they don't reflect much light.

"These objects are darker than coal," he said, "and you might expect to
find no more than one in an area of sky about the size of a full moon."

This accounted for the long delay before the first TNO was identified
seven years ago. It requires a very sensitive camera, but also their
discovery was very much a matter of "believing that they were there",
he said.

It is only in recent years that this has become possible, using a
combination of wide field CCD (charge-coupled device) cameras and large
2.5-metre telescopes. The current generation of CCD cameras can take
images of remarkably faint objects.

"We can see objects that are 15 million times fainter than the faintest
star you could see on a dark night in Connemara," he said.

Observers use a trick of the ancient Greeks to distinguish the planets
from the stars. It involves taking two images a given period of time
apart and looking for near objects that have moved relative to the
background of more distant stars. Knowing the time delay and the
distance travelled gives astronomers estimates of how far away the
object is.

TNOs are of great interest to researchers. They are assumed to be
material left behind after the proto-planetary disc of matter that must
have originally surrounded our sun condensed into planets.

"What we believe we are looking at are the remnant building blocks of
the planets. Samples would tell us much about the stuff from which
planets are made."

Researchers are also interested because the Kuiper Belt is believed to
be the source from which short period comets arise. These include Comet
Temple Tuttle, dust from which produces the annual November Leonid
meteor showers.

Visitors from the Kuiper Belt could eventually become Earth impactors.
TNOs drop out of the belt and move into the solar system proper once
every 100,000 years or so and there are eight or nine known objects
moving between Neptune and Jupiter, he said. "We believe these are
slowly moving into the inner solar system."

The impactor thought to have wiped out the dinosaurs 65 million years
ago was estimated to have been between one and two kilometres across
(sic), but TNOs range from 50km up to 800km, with most falling between
100km and 400km.

It is thought that any TNO making it past Jupiter's gravitational pull
would be broken up into smaller pieces, but these would still represent
a serious threat if they drifted towards us.

There is a move afoot to have the Kuiper Belt renamed the
Edgeworth-Kuiper Belt and to rechristen TNOs as Edgeworth-Kuiper
Objects, said Dr Mark Bailey, director of the Armagh Observatory.

While it does seem that Kuiper did not rely on Edgeworth's work, his
earlier papers are documented and they do predate Kuiper.

It shows that Ireland's size does not militate against its position in
international research.

Copyright 1999, The Irish Times

==================
(2) HILTON BACK SPACE HOTEL

From BBC News Online
http://news.bbc.co.uk/hi/english/sci/tech/newsid_293000/293366.stm

By BBC News Online Science Editor Dr David Whitehouse

The hotel group Hilton International is to become the first sponsor of
a privately funded plan to build a space station. It will be
constructed from used Space Shuttle fuel tanks.

And when the Hilton Orbital Hotel is built, space visionary Arthur C
Clark wants to be there for the opening.

The project, called Space Islands, will connect together Space Shuttle
fuel tanks, each the diameter of a Boeing 747 aircraft. At present they
are the only part of Nasa's Space Shuttle that is not reused.

British Airways are also said to want to become involved in the
project. Under consideration is a survey of BA and Hilton customers
asking them if they would like to take a holiday in space.

They would be asked if they wanted it to be entirely gravity free and
if they would like large windows to view the Earth. Would they like to
take a spacewalk is another possible question.

"There is powerful support for this concept in Washington," said Space
Island Group director Gene Meyers.

He told BBC News Online "There is no technical reason why it cannot be
done."

He hopes that the project will excite major companies to sponsor the
project in the same way that they sponsor the Olympics.

"We need $6 - $12 billion," he said, "That is a fraction of the [$40bn]
cost of the space station that is currently being built by the USA,
Russia and other countries."

The space station would be made out of empty space shuttle fuel tanks.
Currently, they are used once and allowed to fall back to Earth,
burning up in its atmosphere. However they could easily be kept in
space and outfitted as living quarters.

The most optimistic schedule for its construction is six years, given
the money and the will to do it.

"Eventually there could be several of these space stations in orbit,"
says Meyers, "It would even be possible to put one in a figure-of-eight
orbit around the Earth and the Moon. That would be quite a vacation."

The idea of using spent Space Shuttle fuel tanks is not new. It was
once considered by Nasa as the basis for its own space station. However
it was discarded as being too simple. It was possibly also seen as too
commercial for an organisation that sees its role mainly in research
and development.

Up to 100 people at a time could be ferried up to the orbital hotel, if
a second-generation space shuttle was built.

Space visionary Arthur C Clarke has been an enthusiastic backer of the
project for a year.

He was to approach film director Stanley Kubrick to become involved.
Together they designed the famous wheel-shaped space station for the
film "2001 - A Space Odyssey."

But Kubrick's recent death has ended the chance for him to see his
vision turned into reality.

It is no coincidence that in "2001 - A Space Odyssey" part of the space
station is a Hilton hotel. The hotel group paid to be part of the film.
Thirty years later Arthur C Clark has once again approached the company
to be part of the new initiative.

"This space station could be built, there is no reason why it can't"
said Gene Meyers "all we need is for people to find out that it can be
done and then help us do it."

Copyright 1999, BBC

=====================
(3) SNL & JPL PROPOSE $1BILLION INTERSTELLAR EXPLORER

From Scripps Howard News Service
http://www.bergen.com:80/morenews/spacetug199903098.htm

Tuesday, March 9, 1999

By LAWRENCE SPOHN

ALBUQUERQUE, N.M. -- The ultimate road trip, a nearly 100 billion-mile
excursion out of the solar system, is being proposed by scientists at
government laboratories in New Mexico and California.

Their proposed interstellar space cruiser would haul a 1-ton telescope
into the unexplored frontier of interstellar space at 380,000 mph, give
or take a few thousand mph.

Collaborating scientists at the Department of Energy's Sandia National
Laboratories in Albuquerque and NASA's Jet Propulsion Laboratory, in
Pasadena, Calif., say that not only is mankind's first interstellar
mission "doable" next decade, but its potential achievements also make
it extremely worthy.

FULL STORY:
http://www.bergen.com:80/morenews/spacetug199903098.htm

Copyright 1999, Scripps Howard News Service

----------------------------------------
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*

LETTERS TO THE MODERATOR, 10 March 1999
---------------------------------------


(1) ON THE YARKOVSKY EFFECT
    Paolo Farinella <paolof@keplero.dm.unipi.it>

(2) MORE ON THE YARKOVSKY EFFECT
    William Bottke <bottke@astrosun.tn.cornell.edu>

(3) A CHIP OFF THE MOON?
    Rolf Sinclair <rsinclai@nsf.gov>

(4) IS SPACEGUARD TOO CHEAP?
    Richard A Kowalski <bitnik@bitnik.com>

(5) NEMESIS: BILL NAPIER'S SCIENCE FICTION THRILLER
    Michael Paine <mpaine@tpgi.com.au>

=====================
(1) ON THE YARKOVSKY EFFECT

From Paolo Farinella <paolof@keplero.dm.unipi.it>

Dear Benny,

Enzo Zappala's comment in the March 9th CCNet Letters reveals that, as
it was probably the case for other people, he has read the
(oversimplified) press reports on our Yarkovsky work, but not the
original paper published in SCIENCE (March 5th, 1999) or the preprint
available on my website for several weeks before publication
[http://tycho.dm.unipi.it/~paolof].

Our work shows that for multi-km asteroids the Yarkovsky effect can
shift the semimajor axis by 0.01-0.02 AU - not much, but enough to
inject them in one of the many, thin resonances criss-crossing the
inner asteroid belt, as discussed by Migliorini et al. (1998, the same
SCIENCE paper that Enzo mentions) and Morbidelli & Nesvorny (ICARUS,
submitted). The Yarkovsky drift, according to our estimates, increases
by a factor 3-4 the flux into the resonances of small main-belt
asteroids, and thus, indirectly, the flux feeding the Mars-crossing and
eventually the Earth-crossing  populations. In summary: the Migliorini
et al. and our mechanism work in synergy, not as alternatives!

Paolo Farinella

================
(2) MORE ON THE YARKOVSKY EFFECT

From William Bottke <bottke@astrosun.tn.cornell.edu>

Dear Benny,

I would like to comment on Vincenzo Zappala's recent message that the
Yarkovsky effect may not be needed to deliver main belt fragments to the
Earth-crossing region.

Vincenzo correctly points out that the combination of mean motion
resonances with Mars, three body mean motion resonances with
Jupiter-Saturn, and Mars close encounters are now the favored delivery
scenario to bring multi-km asteroids to the NEO region (Migliorini et
al. 1999, Science, 281, 2022). He also correctly points out that the
Yarkovsky effect, a thermal drag force, is too weak to move large
objects very far (~0.01 AU for R = 1-10 km bodies over their
lifetimes).

The point of the Farinella and Vokrouhlicky Science paper is, however,
that the Yarkovsky effect helps resupply the narrow Mars and
Jupiter-Saturn resonances with main belt material.  Collisions probably
cannot do it alone; the total width of the 100 or so tiny resonances
between 2.15 AU and 2.45 AU is ~ 0.03 AU, such that ejecta only has
about a 10% chance of ending up in a resonance after being launched
from its parent body.  Estimates show that there are not enough
moderate-eccentricity multi-km bodies in the main belt to keep the
Mars-crossing asteroids in steady state via these resonances, nor are
their enough multi-km fragments produced by collisions to keep these
resonances filled with fresh material.

Thus, a plausible alternative is that the Yarkovsky effect and the
Migliorini et al. resonances work in concert to provide material to the
inner solar system: (i) A multi-km asteroid is created in a collision,
(ii) it is slowly dragged into a resonance via the Yarkovsky effect,
(iii) the asteroid has its eccentricity pumped up to reach a
Mars-crossing orbit, and (iv) Mars close encounters remove the object
from resonance and eventually move onto an Earth-crossing orbit.

Best regards,

Bill Bottke
Cornell University

=====================
(3) A CHIP OFF THE MOON?

From Rolf Sinclair <rsinclai@nsf.gov>

Re: A Chip off the Moon? <Simon Mansfield>

There was a telescopic search at the Earth's L4 and L5 points in the
'70's by the Lunar & Planetary Lab, U. Arizona. When I mentioned this
at a talk I gave at Northern Arizona Univ. in 1987, a staff member from
the Lowell Observatory pointed out that they had done such a search a
decade or so earlier. (I believe the late Clyde Tombaugh was involved
in this search.) Sorry I don't have the exact references at hand. The
LPL work was published in ICARUS; I don't know where the Lowell work
was published. These labs should be able to give more details.

Rolf Sinclair

P.S. Neither study found anything "natural or artificial" (as the LPL
paper put it).

=====================
(4) IS SPACEGUARD TOO CHEAP?

From Richard A Kowalski <bitnik@bitnik.com>

Benny and Michael,

On the subject of Spaceguard not costing enough to be taken
seriously... I would have to agree and I'll give you a small, somewhat
off topic, but albeit, telling episode.

In the FAQ for my mailing list (Minor Planet Mailing List) I have a
statement that any person can do useful astrometry for under $500 US.
It is assumed that one has a computer, since it is posted on the
internet, but I also assumed a person interested enough could grind a
mirror and build a CCD camera for small money today. The reduction
software is available for free. Donated optics and/or CCDs can even be
found on occasion to lower the costs further.

I was surprised by the  number of responses which I got (from a few
well known amateurs at that) who said I was being disingenuous by
quoting such a small amount.

I stand behind this number (for the above cited reasons) and can see
the amount even dropping further in the not too distant future...

I would not be surprised that governments and other institutions feel
$10 Million per year isn't enough to consider funding Spaceguard too.

"Save the world for only $10 million per year? Ha!"

This might also suggest that we are looking for funding in the wrong
places.

In the past several years, the insurance industry has been taking the
subject of Global Warming seriously because they would be directly
affected by having to pay out claims.

In recent years, attention has been drawn to massive flooding not only in the US
but around the world. There has also been a surge of building along sea
coasts and recent hurricanes have emptied the coffers of these
companies because of damage claims. El Nino is just one other "Global"
event which the insurance companies are affected by.

Granted, asteroids which are "Global Killers" (1 km or larger) would in
effect absolve these companies from having to pay out, because there
wouldn't be anyone to write the check, or to accept it or even a place
to cash it! "Regional Killers", "State Killers" or "City Killers" would
be taken more seriously by these companies because even if one of these
bodies impacted in an ocean, they would have to pay out incredible sums
for property damage (flooding) and human death and injury claims.

Possibly those involved in trying to obtain funding for Spaceguard
through individual governments should instead turn their attentions to
insurance companies instead. Their "bean counters" take disasters into
account every day... Government "beanies" don't...

Just my $0.02

--
Richard Kowalski
Quail Hollow Observatory         Minor Planet Mailing List
http://www.bitnik.com/QHO        http://www.bitnik.com/mp
761 Zephyrhills

"One thing I learned at home, on those nights at home, I learned how to
use a telescope and how to find objects in the sky. You don't do that
by going to a bar and drinking beer"

Clyde Tombaugh - Discoverer of Pluto

==========================
(5) NEMESIS: BILL NAPIER'S SCIENCE FICTION THRILLER

From Michael Paine <mpaine@tpgi.com.au>

Dear Benny,

I have just finished reading NEMESIS, the new science fiction thriller
by astronomer Bill Napier. Arthur C Clarke is quoted on the cover: "The
most exciting book I have ever read" (see also CCNet Digest 4/11/98). I
agree with Sir Arthur!

Not that I am complaining but ... it took me months to gather
information about the NEO hazard for the Australian Spaceguard Survey
web pages. Most of this information is now succinctly covered by Bill
Napier in briefings and other conversations between scientists,
military personnel and politicians - so you can learn all about the NEO
hazard while enjoying a thrilling story.

The paperback version is now on sale in Australia - Big W has it on
special for AU$16 (tip off from Rob McNaught)

Michael Paine

-----------------
CCNet-LETTERS is the discussion forum of the Cambridge-Conference
Network. Contributions to the on-going debate about near-Earth objects,
the cosmic environment of our planet and how to deal with it are
welcome. To subscribe or unsubscribe from CCNet-LETTERS, please contact
Benny J Peiser at <b.j.peiser@livjm.ac.uk>. The fully indexed archive
of the CCNet, from February 1997 on, can be found at
http://abob.libs.uga.edu/bobk/cccmenu.html


*

A CLARIFICATION

From Vincenzo Zapalla <zappala@otoax4.to.astro.it>

Dear Benny,

I completely agree with the comments of Paolo and Bill. However, the
purpose of my letter was different. In fact, the contribution of Yarkovsy
effect to the general problem of the origin of NEA is probably well
understood by myself and all the other colleagues involved in this field.
However, information like that furnished in the article from The New York
Times of March 9 (reported by Henry Fountain) can be highly misleading.
Some readers can understand that Yarkosvky effect alone has solved the
mistery of the origin of NEA. The problem is much more complex. The
aim of my letter was just to address this fact and to put the topic under
a correct light. In this respect, I thank very much Paolo and Bill in having
helped me in doing so.

V. Zappala



CCCMENU CCC for 1999

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