CCNet, 16/2000 - 8 February 2000

added note: ASTEROID 2000 BF19: ALL-CLEAR

    Andrea Milani <>

    The New York Times, 8 February 2000

    MSNBC, Spacenews, 7 February 2000

    SpaceViews, 7 February 2000



From Andrea Milani <>
[as posted on the MPML mailing list, Feb. 8, 13.25 GMT]

I have recomputed the orbit of 2000BF19 taking into account both the
new observations obtained by McNaught tonight and the additional data
of observations on Feb. 1 and Feb. 5 which I received directly form
Jim Scotti.

The new orbit is far enough from the nominal, and in the right
direction, to allow to conclude that the previous 'virtual impactor'
is excluded. However, I will not announce a 'ceased alarm' until our
automatic close approach scan program has completed its run. This
because, as the orbit uncertainty decreases, some virtual impactors
become incompatible with the observations and can be ruled out, but
others increase their probability and could go above the threshold of
detection with our scan method. That is, I will not announce that it
is safe as long as there is the possibility that another virtual
impactor is discovered later. I hope people will not be too impatient
this time.

The scan started a few minutes ago and should take about 4 hours.
Then leave me a few hours to look at the output, also because I have
exams to do (they are the way I earn my living, I am a teacher,
asteroids are a kind of hobby). Moreover, I am not very keen about
working today, because my friend Paolo Farinella is undergoing heart
surgery now. You may rate my attitude as egoistic, being more
concerned about a friend who could die today than about a potential
disaster in 2022, but please take into account that if we now
understand something about how the asteroids came our way, including
that Eros of which so many are speaking, a lot of credit should go to
Paolo Farinella. All things considered, the new announcement should
be issued at around 9 PM European time.

Yours Andrea Milani

MODERATOR'S NOTE: May I express my sympathy with Andrea's comment and
concern: Please let us all hope that Paolo's heart surgery is
successful so that a very good friend and colleague can live and
continue to contribute to our common efforts, goals and future.


Form The New York Times, 8 February 2000


For the fifth time in two years, astronomers have discovered an
asteroid hurtling through space that might collide with the Earth.

The likelihood of collision is considered slim: one chance in a
million. While the projected date of any impact is 2022, astronomers
say additional observations are needed to calculate the orbit of the
asteroid better and to rule out a collision.

The asteroid, 2000 BF19, is about half a mile wide, relatively small by
cosmic standards, and if it struck Earth could do tremendous damage to
part of the planet but would probably not cause planetwide destruction.

It was discovered by three astronomers led by Dr. James V. Scotti using
the Spacewatch Telescope on Kitt Peak in Arizona. They spotted the
object on Jan. 28, and it was tracked until Feb. 3, when it disappeared.

On the same day, the International Astronomical Union by the Minor
Planet Center of Smithsonian Astrophysical Observatory in Cambridge,
Mass., announced the discovery of the asteroid.

The announcement did not mention a possible collision but suggested that
the asteroid should be watched.

The chance of a collision was raised yesterday by Dr. Benny J. Peiser,
who runs the Cambridge-Conference Network, or CCNET, an Internet
newsletter on astronomy.

"The current impact probability of one in a million can easily and
quickly go up or down," Dr. Peiser wrote. In all likelihood, the
asteroid will turn out to be of no risk, he said.

"Only further observations can provide us with the information to
assess the potential danger," he added.

The calculations of the current risk and the projected impact date were
done by Dr. Andrea Milani, an astronomer at Pisa University in Italy,
Dr. Peiser said. The asteroid was expected to pass near Earth every 11
years, next in 2011.

"There are a wide variety of orbits that can fit the observations,"
Gareth V. Williams, an astronomer at the Smithsonian Astrophysical
Observatory, said in explaining the collision uncertainty. Only three
groups, including an amateur astronomer, have been able to track the

"The only people who should be concerned are astronomers who should be
trying to get additional observations," Dr. Williams said. "Since the
arc of observation is so short, it is highly possible that any
additional observations will be sufficient to reject the 2022 impact

Dr. Williams said that in other instances, follow-up observations have
allowed astronomers to rule out collisions. In one case observations
were too limited to let them do so before the object disappeared.

For 2000 BF19, he said, with the asteroid fading fast, a clarification
might take years rather than weeks.

"It's a hefty object," Dr. Williams said. "We would not like an object
of this size to hit us."

Copyright 2000, The New York Times Ltd.

Despite its small  size and small  risk, scientists  are taking it seriously

From MSNBC, Spacenews, 7 February 2000
By Alan Boyle, MSNBC

Feb. 7 —  Another potential asteroid threat has been added to the list
of astronomers’ worries — and although it’s likely to be eliminated
from the list eventually, this one is tricky. Asteroid 2000 BF19 is so
small and faint that it can’t be seen by most amateur telescopes.

THIS ASTEROID, discovered Jan. 28 by the University of Arizona’s
Spacewatch Project, is no “Armageddon”: It’s thought to be much less
than 0.6 miles  (1 kilometer) wide. That takes it out of the category
that scientists say could cause a global catastrophe on Earth.

What’s more, the possibility of a collision in the year 2022 is rated
at roughly one chance in a million. In comparison, NASA estimates the
“background risk” of an asteroid impact — that is, the chance that an
undetected kilometer-wide space rock might collide with Earth — at
between 1 in 100,000 and 1 in a million.

Thus, the asteroid rates a zero on the Torino scale, which was devised
to rate the risks posed by near-Earth objects.

Nevertheless, scientists sent out an urgent appeal for further
observations of 2000 BF19 — as they have at least four times before in
the past two years.  “Shame on the astronomical community if we lose
this dangerous fellow, which is unfortunately quite dim and fading,”
the University of Pisa’s Andrea Milani wrote in an e-mail notice passed
along by the Cambridge Conference Network.

Milani said that the 1-in-a-million collision risk for 2022 depended on
whether Earth’s gravitational pull had an unfortunate effect on the
asteroid’s orbit during a close encounter in 2011 — a phenomenon
astronomers compare to a bullet passing just right through a keyhole
and hitting its target within.

Under just the right (or just the wrong) conditions, the threat of
collision could recur every 11 years, Milani said. Two years ago, the
first such asteroid alert caused quite a stir, particularly since it
came during the publicity buildup for two Hollywood movies,
“Armageddon” (about a killer asteroid) and “Deep Impact” (about a
killer comet). More recent alerts have been greeted much more calmly.

Even though the risk of collision is astronomically remote, Gareth
Williams of the Minor Planet Center at the Smithsonian Astrophysical
Observatory said every call for additional observations had to be taken
seriously. “Sooner or later one of these things will be announced,
and further observations won’t eliminate them” as a potential threat to
Earth, he told MSNBC. “At this time, we’re at the stage of not having
any further observations.”

In the past, amateur astronomers have played a big role in gathering
additional data about the orbits of asteroids so that they could
eventually be excluded as a threat. But BF19, currently in the
constellation Cancer, is already fainter than the 21st magnitude — too
dim for most amateur telescopes to pick up. The asteroid is so small
that astronomers are unlikely to find any traces of it in earlier
photographs, Williams said.

“If past cases are anything to go by, further observations may exclude
the 2022 scenario, but may open up the possibility of an impact in
another year. ... It’s going to be several months before things calm
down,” Williams said.

Scientists estimate that there are 500 to 1,000 potentially hazardous
asteroids wider than a kilometer — and they theorize that asteroids of
such size have in the past caused mass-extinction events such as the
demise of the dinosaurs 65 million years ago.

Astronomers are on track to identify all such asteroids within a decade
or two, according to an analysis published last month in the journal
Nature. However, such estimates do not account for smaller asteroids
that could wreak less widespread damage.

The classic example from the past century is the 200-foot-wide
(60-meter-wide) Tunguska meteorite, which blasted a largely uninhabited
region of Siberia in 1908 with the force of a hydrogen bomb. University
of Hawaii astronomer David Jewitt said last month that there was a 1
percent chance that Earth would be struck by a 1,000-foot-wide
(300-meter-wide) object sometime in the next century.


- 31,207 responses

* The threat is being exaggerated- 31%
* I'm adding it to my list of worries - 24%
* Something needs to be done! Now! - 30%
* None of the above - 15%

Here is a recap of some other asteroid alerts that have been issued in
the past:

1997 XF11: Concern raised in March 1998 about potential impact in 2028.
           Concern eased within days.

1999 AN10: Concern raised in April 1999 about potential impact in 2039
           or 2044. Concern eased in July 1999.

1998 OX4: Concern raised in June 1999 about potential impacts in
          2014-2046 period. Current risk rated at 1 in 10 million.

1999 RM45: Concern raised in October 1999 about potential impact in
           2042 or 2050. Concern eased within days.

Copyright 2000, MSNBC


From SpaceViews, 7 February 2000

A recently-discovered near-Earth asteroid has a slim possibility of
impacting the Earth in 2022, astronomers reported Monday, February 7.

Asteroid 2000 BF19, discovered last month, has about one chance in a
million of colliding with the Earth in 2022, astronomer Andrea Milani
of the University of Pisa in Italy informed astronomers on

The asteroid is thought to be quite small -- less than a kilometer
(0.62 mi.) in diameter. This, combined with the low probability of
impact, keeps the asteroid at a 0 on the Torino scale, a rating system
unveiled last year that combined the size of an asteroid with its
impact probability to compute its risk to Earth on a 0-10 scale.

However, in his communique, Milani urged astronomers to observe the
asteroid now, before the already-faint object becomes too dim to
observe. "This object is visible tonight and is fading, so I rate this
message as scientifically urgent," he wrote.

Several asteroids have been discovered in the last two years with
non-zero impact probabilities. However, in every case but one, those
impact probabilities have become zero as additional observations of the
asteroid permitted refined calculations of its orbit that eliminated
any chance of an impact.

The one exception, 1998 OX4, was lost before additional observations
could be made. It presently has one chance in ten million of hitting
the Earth in January 2038, and less likely impact probabilities in
2044 and 2046.

"In all likelihood, 2000 BF19 will drop altogether from the [Torino]
scale," noted Benny Peiser, moderator of the Cambridge Conference
Network mailing list used to discuss near-Earth asteroids and their
impact hazards. "But until we get peace of mind only further
observations can provide us with the information to assess the
potential danger of this new PHA [potentially hazardous asteroid]."

Copyright 2000, SpaceViews


From, 7 February 2000
Researchers in Italy announced on Feb. 7 the discovery of an asteroid
that has an extremely small chance of hitting Earth in the year 2022.

The asteroid, called 2000 BF19, was discovered by a group of
researchers in Italy who have called upon scientists to make
additional observations to further pin down the course of the space

The asteroid is the fifth one discovered over the past two years with
a potential to hit Earth. The miniscule odds of impact have been put
at 1 in a million, but the chances will likely change as more data is
gathered, researchers said.

The odds could go up or down.

The most likely scenario, repeated with other recently found potential
impactors, is that better data will yield a more certain trajectory,
and 2000 BF19 will be found to be no danger at all. But international
researchers who monitor potentially hazardous Near Earth Objects, or
NEOs as they're called, have settled into an early warning system that
publicizes such findings, in part so that other researchers will study
the object.

Often, quick action is important because the asteroids' orbits take
them into deeper space, where they hide until their next trip around
the sun.

"This should not be rated as a serious concern," said Andrea Milani,
who led the group that found 2000 BF19. "Nevertheless, shame on the
astronomical community if we lose this dangerous fellow, which is
unfortunately quite dim and fading."

Copyright 2000,

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    SPACE.COM, 7 February 2000

    Louis Friedman <>

    Ed Grondine <>


From SPACE.COM, 7 February 2000 

By Robert Roy Britt
Senior Science Writer
A high-ranking U.S. Military official -- speaking in a
non-official capacity -- says the hunt for potentially
Earth-threatening space rocks should be more centralized, and the
Department of Defense could be a primary force behind this project.

Pete Worden, deputy director for Command and Control at the U.S. Air
Force Headquarters in the Pentagon, suggested an array of
micro-satellites should be used to find and study Near Earth Objects
-- asteroids and comets known as NEOs -- in an effort to save money
and speed up the search process.

The idea was welcomed by some in the community of international
researchers who monitor NEOs, but there are reservations about
whether micro-satellites would actually prove cheaper than current
ground-based efforts.

The Department of Defense has no official view on the topic and has
previously sidestepped the issue of greater involvement. Worden
raised the idea on his own in a February 7 essay appearing in CCNet,
a scholarly newsletter that focuses on the threat of asteroids.

"With relatively simple modifications to operations, our future space
surveillance system could produce a comprehensive catalog of NEOs at
little or no expense to the scientific community," Worden said.

While the odds of an earthly impact are constantly revised and
debated, it's the big rocks that keep asteroid hunters ever vigilant.
Current estimates hold that the odds of a civilization destroying
impact in any single year range from about 1 in 100,000 to about 1 in

Worden, a physicist and astronomy researcher who worked on the
Clementine lunar mission, said the current NEO search effort is
bogged down because "decision makers simply are unwilling to spend
scares resources on such an unlikely catastrophe."

Go micro

Worden said micro-satellites, which are cheaper to build and cheaper
to launch, would be particularly effective in rooting out
difficult-to-see asteroids that traverse the space between us and the

Though it helped develop the successful LINEAR asteroid search
program, the Department of Defense has typically wrung its collective
hands over additional involvement in the search for possibly
threatening asteroids. According to Donald Yeomans, an expert on NEOs
at NASA's Jet Propulsion Laboratory, there is a fear of the possible
"giggle factor" that could be produced from the idea of a military
agency hunting for space rocks.

Yeomans said in a telephone interview that the international NEO
community would likely welcome additional help from the military, but
he questions whether an army of micro-satellites would be
cost-effective compared to current ground-based efforts.

"Anytime you use space-based reconnaissance it's frightfully
expensive," Yeomans said. He added that Worden is "taking a pretty
brave stance," given that many in the Department of Defense are not
keen on the idea.

Worden says he has the support of many colleagues. But, he told, "there are also a number who aren't very enthusiastic
about it."

Part of Worden's plan is a more concerted effort to characterize the
composition and structure of NEOs. The makeup of asteroids ranges
from solid blocks of stone and iron to loosely bound piles of rubble.
In truth, researchers know very little about how asteroids are
composed, how they hold themselves together and what would happen the
next time a big one heads earthward.

Knowledge about asteroid composition, researchers agree, is crucial
to determining how to deflect or destroy one that might someday be
found to be on a collision course.

Yeomans agreed with others that while added military involvement
would be a good thing, competition is healthy and other existing
search programs should be continued.

Dr. Benny J. Peiser of Liverpool John Moores University focuses much
of his research on the threat of asteroids, and he also moderates the
newsletter in which Worden's essay was published.

"Let's face it," Peiser said, "without the U.S. military, the Free
World would have been lost long ago. The efforts to safeguard
humanity from future impact disasters, however, will need more
cooperation and funding. Don't rely on the Department of Defense to
save us every time we're in trouble."

Copyright 2000,


From Louis Friedman <>

Pete Worden's essay is notable in that he explicitly rejects efforts
to spend resources on mitigation, and correctly emphasizes the need
for more knowledge. Going beyond this framework has led to a loss of
credibility toward those whose advocate dealing with the NEO threat.

But clearly what Gen. Worden offers is a solution looking for a
problem. He wants a mission for the DoD, and defines a rational one,
based on the need for more knowledge about NEOs. The following
statement from his essay is revealing, "NEO discussions in the United
States have, as I believe they have everywhere, suffered from the fact
that catastrophic NEO impacts are so rare and hence so unlikely to
occur in our lifetimes." One would normally think that the lack of
catastrophic impacts is not something for the discussions to suffer,
but something that would assist the discussions. Unless one want the
threat to be a justification for a mission.

The motivation of trying to find a role for DoD should be carefully
examined. We all can agree on increased observation programs (indeed
The Planetary Society both funds private ones and advocates government
programs), and on space missions of exploration. But astronomical
observation programs and exploration missions are civil pursuits, not
military ones -- and there should be no military mission defined here.
So far, the military has agreed.

Military - civil cooperation is to be applauded. This was wisely
stated in  the founding act for a civil space agency. The LINEAR and
other programs prove that. But encouraging military assets and
cooperation in this civil endeavor is very different from defining a
military mission. If a deterministic threat is ever identified so
that defense of the world, or the country, is required then we can
assign a military mission. But until then, making the search for
knowledge about NEOs a military function will inhibit scientific and
international cooperation, and turn the focus from astronomy and
science to devices and exercises. It makes no more sense for the NEO
threat to become a military mission, than it does for fighting the
threat of global warming  (maybe less, at least the global warming
threat is a known one). Both need to be dealt with, but appropriately.

Louis Friedman
Executive Director, The Planetary Society


From Ed Grondine <>

Hello Benny -

I want to take a few minutes to highlight a few key points of Pete
Worden's personal observations, which as he pointed out must not
be taken as official Department of Defense or US policy, at least
not yet, anyway.

Worden started by calling attention to smaller objects. Like all
of those intimately familiar with the upper atmosphere explosions
detected by US warning systems, explosions caused by the impact of
these smaller objects, he knows full well the immediate threat
they present, a threat which is much, much greater than many

In my opinion, and I differ from Worden on this, it is going to be
impossible to rely solely on ground based telescopes of the LINEAR
class from the United States' Department of Defense to perform the
Earth based survey in its entirety. I would be interested to hear
from other CCNet participants on this, (and no doubt Benny you are
already hearing from many of them in  quite strong words), but my
first impression is that the number of objects is simply too
great, and viewing time too limited, for the United States' Air
Force to handle the NEO detection problem alone. Whatever the
Air Force NEO detection program becomes, I think that international
cooperation is going to be necessary and that NASA and the MPC
will be needed.

The big news in Worden's letter is that he is going to advocate
the use of Minotaur launchers to help deal with the NEO problem. 
Minotaurs are small launchers constructed by Orbital Sciences
corporation from military grains decommissioned as a result of
arms control treaties. So as to not interfere with the commercial
market, these launchers are being made available solely for
government programs, at a cost of a little over $10 million per
launch. Worden is advocating using these Minotaur Launchers to
help the government deal with its nagging NEO problem in two ways:
first, for the launch of small orbiting telescopes; and second,
for tests of asteroid and comet intercept technologies.
Small telescopes in orbit may provide a good start for solving the
NEO problem. Still, these small orbiting telescopes will have
limited detection abilities, and thus be able only to provide
warnings with entirely too short lead times -  as compared with,
say, a lunar based observatory. The cost of data reduction from
these small orbiting telescopes is likely to be much greater than
Worden anticipates, not only for the skilled personnel, but also
the advanced computers and storage technologies the NEO tracking
task will require. Once again, given the limited number of skilled
orbital mechanicians, as well as the limited number of very large
telescopes, international community will likely have to be

On Worden's second point, while these Minotaur launchers may also
prove to be of great help in developing intercept technologies,
interceptions of the larger objects are going to have to be done
some distance away from the Earth. The payload capacity of the
Minotaurs, around 750 pounds (say 300 kilos), is simply too small
to be of much use in testing the final designs for the intercept

Finally, as Worden points out, smaller objects can be diverted or
destroyed with non-nuclear charges. But larger objects will
require the use of nuclear charges, and clearly these nuclear
charges will have to be stored at the ready on Earth, along with
their deep space transfer stages. International agreements on
these storage facilities, as well as agreements on steps to assure
the storage facility or facilities' security, will have to be
negotiated by the responsible national representatives.

So far this is just my opinion, and I look forward to hearing
those of others on these matters.

Best wishes to all -

The CCNet is a scholarly electronic network. To subscribe/unsubscribe,
please contact the moderator Benny J Peiser <>.
Information circulated on this network is for scholarly and
educational use only. The attached information may not be copied or
reproduced for any other purposes without prior permission of the
copyright holders. The fully indexed archive of the CCNet, from
February 1997 on, can be found at



From Andrea Milani <>
Sent: 08/02/00 18:21

Our fully automated program "" has completed a new scan of 2000
BF19, and I can announce that, with the new observations from McNaught
(Feb. 7) and the data from Scotti of Feb.1 and Feb.5, which were
previously not available (and I would like to know why; please do not
remove this comment), the orbit of 2000 BF19 is incompatible with an
impact in 2022, with an impact in all the other dates which were
previously possible, and in fact cannot pass any closer than 0.038 AU
from the Earth for the next 50 years.

It is now time to look at this 'event' with calm, and to try and figure
out how it was handled, what we have learned from this case (which was,
again, different from the previous ones), and how to do better next

I would like to anticipate only one comment. The nominal (best fit)
orbit of 2000 BF19 never had an especially low MOID, that is the ellipse
of its orbit was well separated from the ellipse of the orbit of the
earth. But, the orbit was very uncertain, thus also the MOID was
uncertain, and with the data available until yesterday we could not
exclude a MOID essentially zero. Unless our program had been scanning
all cases, with a rather generous limit on the MOID, we would not have found
that there was a possibility of impact. In the next few days I will try to
put online all the data allowing the other specialists in celestial
mechanics to evaluate our computations, and to learn the mathematical
lesson from this case, which I believe should be summarized as follows:
everything should be given with an uncertainty! and the other programs called by it have been written mostly
by Steve Chesley and myself, with contributions by many other people.

Andrea Milani

PS I am sorry to have mixed personal and scientific considerations in my
previous messages, but since essentially all people working in our
field know him, I would like to inform that Paolo Farinella is
undergoing an hearth transplant now.

Andrea Milani
Dipartimento di Matematica
Via Buonarroti 2

tel. +39-050-844254 fax +39-050-844224
cellular phone +39-0329-8124014

CCCMENU CCC for 2000