http://www.boulder.swri.edu/clark/clark.html
Report to “Cosmic Objects PMP” on
AIAA/B612 Planetary Defense Workshop
Clark R. Chapman
Southwest Research Inst.
Boulder, Colorado, USA
32nd Session of Erice International Seminars
on Planetary Emergencies
Erice, Italy
25 August 2004
Planetary Defense Conference
Overview
 Mixed engineering/interdisciplinary emphases,
sponsored by AIAA, Aerospace Corp., B612
 4 “DEFT” scenarios offered as baseline for
study months in advance
 Congressman Dana Rohrabacher
 Considerable media coverage (esp. AL00667)
though steep fees prohibited broad participation
 Post-conference “white paper” hammered out,
but not adopted (yet) by AIAA
 Web-site has complete videos, pdf’s:
http://www.planetarydefense.info/
The Four DEFT Scenarios:
Other Considerations
Remember:
an impact scenario is
unprecedented in
historical times; there
are no protocols to deal
with one, nor is there a
base of experience with
an impact’s unique
social and physical
repercussions…
 Aramis is multi-km asteroid discovered with 3
decades warning; best simulates ever-changing
(generally improving) knowledge of impactor and
impact circumstances.
 Athos is 200 m S-type (with moonlet!), 10 years
 D’Artagnan is 120 m NEA, will hit Europe in just 5
years, necessitating a “crash” program
 Porthos is 2x1x1 km comet, hits US in 2015
Major Themes of Conference
 Strong emphasis on unknown physical properties, thus
unpredictable behavior, of NEAs
 Better understanding of technical issues involving
refinement of NEA trajectory after discovery
 Strong emphasis on slowly-acting pushes for
deflection as distinct from blowing them up (although
this was bitterly argued afterwards in drafting the white
paper)
 Welcome input (though less well developed)
on social and political issues
 Broad cultural input sets the context (Larry
Niven, Oliver Morton, John Logsdon) as well
as legal, economic, and policy inputs.
The Impact that Didn’t Happen:
AL00667, 13/14 January 2004
 Nominal MPC Confirmation Page ephemeris, based on 4 LINEAR
positions, suggests impact in 24 hr (few hrs after Bush space speech)
 Posting noticed by amateur astronomers, discussed on Yahoo’s MPML
while MPC staff, professional astronomers “in the dark”
 Cloudy skies in much of Europe and USA prevent definite follow-up
 Steve Chesley (JPL NEO Program Office) calculates 10% - 40% chance
of impact, in northern hemisphere, during next few days of ~30 m body
 Midnight considerations to report Torino Scale = 3 prediction
 Lucky ad hoc e-mail connection enables amateur astronomer Brian
Warner, with 20-inch telescope, to search for “virtual impactors”
 Warner finds no object; LINEAR recovers object; calculations few hrs
before Bush speech place it 10 times farther away, impact ruled out
 Czech recovery next night provides designation 2004 AS1
LINEAR site in N.Mex.
Attributes of the AL00667 Case
 Predicting imminent, “final plunge” impacts is not in the
The NEO Confirmation Page


Brian Marsden
Palmer Divide Observatory






scope of the Spaceguard Survey (LINEAR, MPC, JPL NEO
Program Office, NEODys, IAU WGNEO, etc.)
A system that notifies observers to “confirm” very preliminary
NEOs necessarily makes the data public; and if data indicate
a possible impact, they cannot be ignored
AL00667 positions had larger-than-usual uncertainties (we
now know); but analysis of trajectories within usual
uncertain-ties yielded 40% impacting the Earth; there was no
mistake
But AL00667 data were delayed or held private; not available
at all to experts, e.g. at Lowell Observatory, Univ. of Pisa
Is a public announcement ethically required if there is a
professional calculation of >10% impact chance?
Should Bayesian statistics be folded into calculation?
Communications network for AL00667 was mainly ad hoc,
unfunded, and cannot be relied on in future
Until now, only rudimentary (at best!) protocols, plans to
handle out-of-scope, unexpected cases: NASA is changing!
News media did not hype (or even notice) event, until this talk
Suggestions and Recommendations
in Aftermath of AL00667
 Should Spaceguard infrastructure be enhanced
to operate “24/7” and handle imminent impacts?
NO: mismatched priorities; only few-% chance
that next small impactor will be seen before it hits
 YES: only if “SDT Report” is implemented with
system optimized to find smaller impactors

“SDT Report”
August 22, 2003
 Should there be plans/protocols for best-effort
handling of unexpected, out-of-scope cases?

YES: public expects responsible, professional
responses; we were lucky this time
 Instead of “one-night-stand” preliminary data
being held private by LINEAR/MPC, should data
be made immediately available to qualified
international asteroid orbit specialists?


MPC says “NO”: unverified data can be misused
I say “YES”: preliminary, time-urgent, noisy data
are normal in science; independent calculations
are essence of open science. Why keep private?
In the Post 9/11 World...
What are the potential
consequences of the
remote threat of an
asteroid impact catastrophe?