PLEASE NOTE:


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CCNet SPECIAL: THE SPACEGUARD DEBATE IN THE HOUSE OF LORDS
----------------------------------------------------------

     QUOTE OF THE DAY

     My Lords, I am sorry that the Minister has been subjected
     to the giggle-factor, which is a problem involved with this subject.
     Does he agree on the general principle that if nations are prepared to
     pay to preserve their civilised past for the current generation, should
     they not be equally prepared to pay for the preservation of a civilised
     future for the next generation? Would not a first step in this
     direction be to subscribe to a national spaceguard centre as part of a
     European contribution to a global spaceguard programme which could
     benefit the future of all mankind?
     (Lord Tanlaw in the House of Lords, 15 June 1999)


(1) MY NOBLE LORDS, THE IMPACT HAZARD WON'T GO AWAY, YOU KNOW
    Benny J Peiser <b.j.peiser@livjm.ac.uk>

(2) THE SPACEGUARD DEBATE IN THE HOUSE OF LORDS
    Lords Hansard Home Page

(3) NO PLANS TO COMBAT ASTEROID THREAT
    BBC Online Network, 15 June 1999

(4) HOUSE OF LORDS RESPONSE
    Michael Paine <mpaine@tpgi.com.au>

(5) AN ANSWER TO A QUESTION ABOUT PROBABILITIES
    Paul W. Chodas" <paul.chodas@jpl.nasa.gov>

(6) FOUR WEDDINGS & AN APOCALYPSE?
    Robert Clements <Robert.Clements@dva.gov.au>


==================
(1) MY NOBLE LORDS, THE IMPACT HAZARD WON'T GO AWAY, YOU KNOW

From Benny J Peiser <b.j.peiser@livjm.ac.uk>

What should Britain contribute to international efforts to detect
hazardous asteroids and prevent them from impacting planet Earth?
"My Lords, I believe that prayer would certainly be a key part of
any strategy". Believe it or not, but this is how Britain's minister
for Trade and Industry, Lord Sainsbury of Turville, responded to
questions raised yesterday in the House of Lords. Yet apart from
cracking the odd joke, the government, it would appear, has passed the
buck - to the European Space Agency. Regrettably, the science minister
failed to mention that ESA and other funding agencies are actually
supporting the idea of setting up national Spaceguard centres under
some form of European umbrella organisation.

Despite yesterday's rather disappointing outcome, it is important to
stress that the government, nevertheless, has again expressed its
general support of the Spaceguard project. As so often, its hesitation
is mainly due to budgetary restraints, in short: who is going to pay
for the British Spaceguard project we have been lobbying for? It seems
clear to me that all of these questions concerning setting-up, funding
and organising a first fully funded Spaceguard Centre in Europe need to
be addressed in greater detail at separate meetings with Government
officials.

Let's not forget that the impact hazard won't go away. It is worth
reminding politicians and funding agencies that only in the last two
weeks, during which Lord Sainsbury was busy preparing his Spaceguard
statement, no less than 12 near-Earth asteroids have been discovered,
two of which are potentially hazardous - to individuals just as much as
to any short-sighted government.

Benny J Peiser

=======================
(2) THE SPACEGUARD DEBATE IN THE HOUSE OF LORDS

From the Lords Hansard Home Page
http://www.parliament.the-stationery-office.co.uk/pa/ld199697/ldhansrd/pdvn/lds99/text/90615-02.htm#90615-02_star0

Tuesday, 15 June 1999, 2.50 p.m.

Spaceguard Programme

2.50 p.m.

Lord Tanlaw asked Her Majesty's Government:

What steps are being taken to form a national spaceguard centre, as
part of a European spaceguard programme, to improve the assessment and
probability factor of impact hazard of a near earth object on the
continent of Europe or in the seas surrounding it.

The Parliamentary Under-Secretary of State, Department of Trade and
Industry (Lord Sainsbury of Turville): My Lords, the Government take
the potential threat of impact by near earth objects very seriously,
but we regard it as an issue where a common international approach is
essential. The UK therefore supported a recent workshop on monitoring
programmes for asteroids and comets in Turin earlier this month, which
was sponsored by the European Space Agency and the Spaceguard
Foundation among others. The European Space Agency is also mounting a
study to produce a system for the co-ordination or the world-wide
capability in near earth object research.

At the present moment, the Government have no plans to set up a
national spaceguard agency, but we will consider the possibility when
we receive the report of the Turin meeting. Any additional work
undertaken in the UK must have benefit over and above that being taken
internationally.

Lord Tanlaw: My Lords, I thank the Minister for Science for that
Answer, which I shall study with interest. Is he aware of the most
recent astronomical data which forecasts that a potentially hazardous
asteroid designated 1999 AN 10, weighing approximately 2 million tonnes
and a kilometre in size, will miss the earth by only 24,000 miles on
7th August 2027 and will possibly impact on its return in 2044?

Is he also aware that, unlike a NATO missile which travels at
approximately 500 miles an hour on a pre-programmed trajectory, AN 10
is approaching earth at 25,000 miles an hour on a chaotic orbit and
will require a more detailed observational data before the
International Astronomical Union can definitely certify it as harmless
in the years following its approach in the year 2027?

May I therefore ask the noble Lord the Minister for Science--I am
sorry, but the issue is somewhat technical--how does he intend to
calculate the risk for the next generation posed by the low probability
but high consequence threat of 1999 AN 10 and other potentially
hazardous asteroids which have a non-zero impact probability?

Furthermore, is the noble Lord the Minister for Science aware that only
10 per cent of near earth objects which could be classified as
hazardous have been identified so far?

Lord Sainsbury of Turville: My Lords, I am aware of the situation and
all that information on asteroid 1999 AN 10. It was discovered in
January. The estimated probability is one in 500,000 of colliding with
the earth during its 2024 encounter (sic). It is therefore extremely
remote. It is important that this information is transmitted regularly
and we hope that in due course the spaceguard website will convey the
information to the public.

Lord McConnell: My Lords, does the Minister agree that if such a centre
is to be established in the United Kingdom the obvious place is Armagh
observatory in Northern Ireland where they have the experience, have
undertaken a great deal of research and where work can be carried out
most effectively?

Lord Sainsbury of Turville: My Lords, one of the key issues in this
regard is that any programme of detection or deflection should be on an
international basis. In view of the fact that we would not be able to
tell where such things were going to land until the last moment, it
would be absurd if each country were to have its own detection and
deflection programme. Therefore, it is important that we have an
international effort. The ESA is working on an international effort.
When it has been produced we will examine what contribution we can make
and the Armagh observatory will be an obvious candidate to play a part
in that.

Lord Winston: My Lords, in addition to consulting other agencies, has
the Minister considered consulting the right reverend Prelates?

Lord Sainsbury of Turville: My Lords, I believe that prayer would
certainly be a key part of any strategy.

Viscount Davidson: My Lords, is the noble Lord aware that the asteroid
has already landed and is called William Hague?

Baroness Nicol: My Lords, am I right in believing in the odds quoted by
the Minister are twice as good as the odds of winning the lottery? Does
not that give him cause for concern?

Lord Sainsbury of Turville: My Lords, the odds are extremely remote and
are comparable to winning the National Lottery. That means we should
have one instance about every 100,000 years.

Lord Mackie of Benshie: My Lords, how does the Minister propose to
deflect these objects?

Lord Sainsbury of Turville: My Lords, the main consideration in
deflection, if it ever gets to that point, is that the longer time one
has between the time one observes the object and the time of impact the
easier it is to deflect it because one can deal with less force. A
number of proposals have been made ranging from impact on the asteroid,
to nuclear weapons, to detonation on the surface of the asteroid.
Clearly, in most cases, if we observe it early enough it would be
possible to think of a strategy to deal with it.

Lord Wilberforce: My Lords, is the Minister aware of the fact that the
name of spaceguard and the concept of it was devised many years ago by
the eminent science fiction writer, Arthur C. Clarke, now Sir Arthur
Clarke, who is a British subject and has his own telescope? Does that
not furnish a very strong reason why we should have our own national
agency, no doubt working with the international agencies, in order to
draw on the great experience and imagination of that great writer?

Lord Sainsbury of Turville: My Lords, I must disagree. There are more
important considerations as to whether we have our own agency. The
first question is whether work should be done by any of the current
bodies rather than invoking new agencies.

Lord Tanlaw: My Lords, I am sorry that the Minister has been subjected
to the giggle-factor, which is a problem involved with this subject.
Does he agree on the general principle that if nations are prepared to
pay to preserve their civilised past for the current generation, should
they not be equally prepared to pay for the preservation of a civilised
future for the next generation? Would not a first step in this
direction be to subscribe to a national spaceguard centre as part of a
European contribution to a global spaceguard programme which could
benefit the future of all mankind?

Lord Sainsbury of Turville: My Lords, I would not wish to imply in any
way that this is a trivial issue. It is a serious issue because mainly,
while the chances of impact are extremely small, the impact of any
object more than a kilometre in length could be considerable.
Therefore, we propose to work through ESA. Of all subjects which come
before this House, this is one in respect of which an international
effort is the key. We shall play our part in that rather than acting
independently.

==================
(3) NO PLANS TO COMBAT ASTEROID THREAT

From the BBC Online Network, 15 June 1999
http://news.bbc.co.uk/hi/english/sci/tech/newsid_370000/370069.stm

The UK Government said on Tuesday that it had no immediate plans to set
up a special centre to tackle the threat of asteroids hitting the
Earth, despite warnings of an "extremely serious" risk.

The Science Minister said the government would look at setting up a
National Spaceguard Agency following calls in the House of Lords for
such a body, but not in the near future.

Lord Sainsbury told the House the government took the potential threat
of a collision with an asteroid "very seriously", and that it was an
issue where a "common international approach was essential"

But he said that it was not something for which there were any plans at
present.

Giant rock

He was responding to a call from crossbencher Lord Tanlaw, who cited
the case of a "potentially hazardous" rock, weighing two million tonnes
and measuring one kilometre across, that may hit the Earth in 2044.

He told peers at question time that scientists predicted the asteroid,
1999 AN10, would miss the Earth by only 38,000 kilometres in 2027 but
could "possibly impact" on a return visit.

Lord Tanlaw said a UK Spaceguard centre should be set up as part of a
European Spaceguard programme to monitor so-called Near Earth Objects
(NEOs).

He said 1999 AN10 posed a "risk for the next generation" which was a
"low probability but a high-consequence risk". Lord Sainsbury said the
possibilty of the asteroid hitting Earth was "extremely remote".

The estimated probability of an impact from the asteroid, discovered in
January, was one in 500,000, he said.

Copyright 1999, The BBC

=======================
(4) HOUSE OF LORDS RESPONSE

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

Dear Benny

I assume you will be swamped with comments over this one but...

The BBC item "No Plans to combat asteroid threat"
http://news.bbc.co.uk/hi/english/sci/tech/newsid_370000/370069.stm
was extremely disappointing. UK citizens can rightly feel as ashamed of
their elected representatives as we do towards the Australian
government. To say that 1999AN10 is a "risk for the next generation" is
outrageous.

One apparent problem is that politicians seem to have assumed that
1999AN10 is the only risk to Earth and since this risk is only 1 in
500 000 the issue is not worth worrying about. This is despite the
efforts of David Morrison and others to point out that the risk from
1999AN10 is much less than the risk from an undiscovered (large)
asteroid hitting the Earth in any one year.

Michael Paine
The Planetary Society Australian Volunteers

======================
(5) AN ANSWER TO A QUESTION ABOUT PROBABILITIES

From Paul W. Chodas" <paul.chodas@jpl.nasa.gov>

Dear Benny,

Perhaps I can shed some light on the recent questions raised by Gerrit
Verschuur concerning impacting probabilities. It seems to me that
Gerrit is confusing the encounter of 1999 AN10 in 2027, when impact
*is not* possible, with the encounters in 2044 and 2046, when impact
*is* remotely possible. The 3-sigma uncertainty ellipse currently shown
on our web page <http://neo.jpl.nasa.gov> depicts the situation in
2027. The ellipse is so elongated that it appears simply as a line
segment, but it is in fact about 1000 km wide at its center. The
diagram is drawn in what is often called the impact plane, which is
more or less the view from the approaching asteroid. (Strictly
speaking, the impact plane is the plane perpendicular to the incoming
asymptote of the asteroid's hyperbolic orbit relative to the Earth.)

The asteroid will pass directly through the impact plane at some point,
and we would like to know where this point lies. If the point is on the
circle representing the Earth, then a collision will occur. The plus
sign denotes the point where the nominal orbital solution passes
through the plane, and as it turns out, it is about 200,000 km from the
center of the Earth. But, asteroidal orbits are never known precisely,
and there is a whole range of possible orbital solutions for 1999 AN10
which are consistent with the 100-or-so observations. Each possible
orbit solution has a 'probability density' associated with it, which is
a way of quantifying the likelihood that it is close to the true orbit.

There is a corresponding probability density for each point in the
impact plane, which, similarly, is a way of quantifying the likelihood
that the point is close to the point where the true orbit will pass.
Think of colouring each point in the impact plane with a shade of gray
corresponding to the probability density at that point. The darkest
point would be at the center of the ellipse, since it is the most
likely point. The uncertainty ellipse is really just a contour line of
the probability distribution describing where the asteroid will pass
through the impact plane, essentially a contour line of constant shade
of gray.

The reason the ellipse is so elongated in the diagram is that we are
projecting a fairly uncertain orbit 28 years into the future, during
which time the asteroid makes 16 revolutions about the Sun, and the
orbital dynamics causes the position uncertainty to spread out along
the orbital path while remaining tightly constrained perpendicular to
the orbital path. In 2027, then, the possible positions of AN10 form a
long skinny tube around the nominal orbital path. When projected into
the impact plane, these positions form the elongated ellipse you see.

By drawing the ellipse line at the 3-sigma level (3 standard
deviations), we capture a 99 percent likelihood that the asteroid will
pass within the contour. (Granted, all of this assumes that we are
using a reasonable probabilistic model on the observational errors, but
let's assume that for now.) The 3-sigma ellipse approaches no closer
than 37,000 km to the center of the Earth (i.e. about 5.8 Earth radii),
ruling out an impact in 2027. (I'm not sure where the 39,000 km figure
quoted by Gerrit comes from, but I believe we are referring to the same
parameter here.)

What about that one percent chance that the orbit will lie outside the
3-sigma ellipse?  After all, the probability distribution doesn't just
drop to zero at 3-sigma, it decays exponentially.  It turns out for
AN10 that the minimum contour which can impact the Earth in 2027 is at
the 161-sigma level! This corresponds to an exceedingly small
probability, which I consider to be indistinguishable from zero. Thus,
an impact in 2027 is essentially impossible.

Now, the situation in 2044 is entirely different. If one were to draw
the uncertainty ellipse for this encounter it would be greatly
extended, 10s of AU long and less than 1 km wide; more significantly,
it slices right across the Earth. In fact, the chaotic dynamics of the
2027 close approach make it inappropriate even to talk of an
'uncertainty ellipse' for post-2027 encounters: we must speak of
3-sigma 'confidence regions', which are no longer elliptical. In the
vicinity of the Earth, however, the confidence region is simply a thin
line crossing the Earth (visualize a circle representing the Earth with
a line slicing across).

The precise width of the confidence region lying across the Earth in
2044 is difficult to calculate, but it is not particularly relevant in
computing the probability of impact. The relevant parameter is the
local linear probability density along the axis of the confidence
region, which can be estimated using Monte Carlo methods. For 1999 AN10
in 2044, I estimate a probability density of about 1.5 x 10^-10 km^-1
along the confidence region, which, when multiplied by a chord length
of about 12,000 km across the Earth disk, yields a probability of
impact of about 2 x 10^-6.

One could draw a separate target plane diagram for almost any year
after about 2034. Each would show one or more thin-line confidence
regions cutting across the diagram, each line corresponding to a
different keyhole in the 2027 uncertainty ellipse. My analyses and
those of Andrea Milani et al. have uncovered only the two confidence
regions in 2044 and 2046 which actually intersect the Earth (at least
as far as the year 2070). The probability of impact in 2046 is about
ten times smaller than in 2044.

One final point to emphasize is that these probabilities are by no
means fixed. As more observations of 1999 AN10 are obtained, the
nominal orbital solution will change, the range of possible orbital
solutions will be better constrained, and the probabilities of impact
will change. It is our fond hope and expectation that the upcoming
observations of 1999 AN10 will drive its probabilities of impact down
to zero.

Cheers,
Paul Chodas

=================
(6) FOUR WEDDINGS & AN APOCALYPSE?

From Robert Clements <Robert.Clements@dva.gov.au>

Re: SCIENTISTS LOSE HUGH ASTEROID
    THE INDEPENDENT (London), 15 June 1999

Not sure if the typo was intentional or not; but the idea of an
asteroid called Hugh strangely appeals (better than 1999 AN10, which is
probably doomed to be dubbed 'Bruce Willis'). Are you planning 4
weddings & an apocalypse?

All the best,

Robert Clements <Robert.Clements@dva.gov.au>
<http://www.ausnet.net.au/~clemensr/welcome.htm>

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