Clark R. ChapmanSouthwest Research Institute Boulder, Colorado, USA,

and “The B612 Foundation”

Clark R. ChapmanSouthwest Research Institute Boulder, Colorado, USA,

and “The B612 Foundation”

2004 Planetary Defense Conference: 2004 Planetary Defense Conference: Protecting Earth from AsteroidsProtecting Earth from Asteroids

Garden Grove CA USA 23 February 2004Garden Grove CA USA 23 February 2004

2004 Planetary Defense Conference: 2004 Planetary Defense Conference: Protecting Earth from AsteroidsProtecting Earth from Asteroids

Garden Grove CA USA 23 February 2004Garden Grove CA USA 23 February 2004

NEO IMPACT SCENARIOSNEO IMPACT SCENARIOS

Session 3-PD-3 “Threats & Consequences II” AIAA-2004-1416

Session 3-PD-3 “Threats & Consequences II” AIAA-2004-1416

http://www.boulder.swri.edu/clark/clark.html

In the Post 9/11 World...

What kinds of impact What kinds of impact predictions do we predictions do we really have to plan for? really have to plan for? How does society respond to real (or imagined) How does society respond to real (or imagined) threats? threats? It’s more than engineering, folks!It’s more than engineering, folks!

Sizes, Impact Frequencies of NEOs

DustDust

Boulder

Boulder

Build

ing

Build

ing

MountainMountain

Second

Second

WeekWeek

Mill

enniu

m

Mill

enniu

m

500,000 yr500,000 yr

100 Myr

100 Myr

Leonid meteor showerLeonid meteor shower

Peekskill meteoritePeekskill meteorite

Tunguska, 1908

SL9 hits

Jupiter 1994

SL9 hits

Jupiter 1994

K-T mass extinctor, 65 Myr ago

Smallest, most frequent

Smallest, most frequent

Huge, extremely rareHuge, extremely rare

15 km15 km

Asteroid Size Distribution: How Often Impacts of Different Energies Happen

Courtesy Al Harris

Death Threat from Impacts, by Asteroid Diameter and Location of Impact

Statistical mortality from impacts, post-Spaceguard, distinguished by size and location of impact (NEO Science Definition Team [SDT], 2003)

SDT tsunami hazard is divided by 10 (think deaths, not property damage)

Land impacts by <100m asteroids (Tunguskas) are objectively important, but they also occur MUCH more frequently than Global destroyers

Tunguskas and their smaller cousins may dominate popular interest in the Tunguskas and their smaller cousins may dominate popular interest in the impact hazard, and hence the work of the NEO community.impact hazard, and hence the work of the NEO community.

Wo

rld

wid

e D

eath

s (A

nn

ual

)

Wo

rld

wid

e D

eath

s (A

nn

ual

)

Asteroid Diameter (km) Asteroid Diameter (km)

Max

Nominal

Min

Tsunami

Land

Global(For nominal case)

The Four DEFT Scenarios: Other Considerations

Aramis best simulates ever-changing (generally improving) knowledge of impactor and impact circumstances. Other cases would be similar.

Who will inform what officials about these threats?

Technical and political arguments in a context of worldwide anxiety and fear.

Preparation for evacuation, storing food, post-disaster relief (if deflection is uncertain or fails).

Remember: an impact scenario is unprecedentedunprecedented 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…

http://www.aero.org/conferences/planetdef/Impact_Scenarios.pdf

Impacts of Practical Concern

Case Studies of Potential Impact Disasters (in my 2003 OECD study)

Nature of Devastation.

Probability of Happening, in 21st century.

Warning Time.

Possibilities for Post-Warning Mitigation.

After-Event Disaster Management.

Advance Preparation. What can we do now?

Six case studies, exemplifying the different sizes and types of impact disasters, were discussed in these terms:

Six case studies, exemplifying the different sizes and types of impact disasters, were discussed in these terms:

a.a. Civilization destroyer: 2-3 km asteroid Civilization destroyer: 2-3 km asteroid or comet impactor comet impact

b.b. Tsunami-generator: ~200 m asteroid Tsunami-generator: ~200 m asteroid impacts in the oceanimpacts in the ocean

c.c. ~200 m asteroid strikes land~200 m asteroid strikes land

d.d. Mini-Tunguska: once-a-century Mini-Tunguska: once-a-century atmospheric explosion (30-40 m body)atmospheric explosion (30-40 m body)

e.e. Annual multi-kiloton blinding flash in Annual multi-kiloton blinding flash in the sky (4 m body)the sky (4 m body)

f.f. Prediction (or media report) of near-Prediction (or media report) of near-term impact possibilityterm impact possibility

We just experienced Case (f) We just experienced Case (f) threatening a Case (d) threatening a Case (d) LAST MONTH!LAST MONTH!

d. “Mini-Tunguska”: Once-in-a-Century Atmospheric Explosion

Nature of Devastation. 30-40 m “office building” rock hits at 100 times speed of jetliner, explodes ~15 km up with energy of 100 Hiro-shima A-bombs. Weak structures damaged/destroyed by hurricane-force winds out to 15 km. If over land, dozens or hundreds may die, especially in poor, densely populated areas (minimal damage in desolate places).

Probability of Happening. Once-a-century, but most likely over an ocean or sparsely-populated area.

Warning Time. Very unlikely to be seen beforehand; no warning at all.

Mitigation Issues. Little can be done in advance (an adequate search system would be very costly). Rescue and recovery would resemble responses to a “normal” civil disaster. No on-the-ground advance preparation makes sense, except public education about this possibility.

Mini-Tunguska

f. Prediction (or Media Report) of Near-Term Impact Possibility

Nature of the Problem. Mistaken or exaggerated media report (concerning a near- miss, a near-term “predicted” impact, etc.) causes panic, demands for official “action”.

Probability of Happening. Has already happened several times, certain to happen again in next decade. Most likely route for the impact hazard to become the urgent concern of public officials.

Warning Time. Page-one stories develop in hours; officials totally surprised.

Mitigation Issues. Public education, at all levels of society: in science, critical thinking, and about risk, in particular. Science education and journalism need improvement with high priority.

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% - 25% chance of impact, in northern hemisphere, during next few days of ~30 m body

Midnight considerations to announce 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 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 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

There have been only rudimentary (at best!) protocols, plans to handle out-of-scope, unexpected cases

For once, news media did not hype (or even notice) event

The NEO Confirmation Page

Palmer Divide ObservatoryPalmer Divide Observatory

Brian MarsdenBrian Marsden

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

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?

“SDT Report”

August 22, 2003

NEO Impact Scenarios: Public Issues

Whether people actually “panic”, impact predictions generate anxiety and demands for action, for which no plans exist

The Torino Scale provides just a first cut estimate of how serious a prediction is (but remember Homeland Security scale!)

Public relations issues will evolve as technical knowledge about impactor, time, location of impact evolves

“Trustworthy” handling of deflection

Many unprecedented issues involving evacuation, contingencies, disaster relief

National, international responsibilities?

Public Perception

While “known” to many from movies and the news, a serious impact disaster has never been experienced in recorded history.

The tiny chances and huge consequences are extremely difficult for people to relate to.

The impact hazard is “dreadful” (fatal, uncontrollable, involuntary, catastrophic, increasing…) and apocalyptic (with religious or superstitious implications for many). Public response to a real impending impact is expected to be exaggerated (e.g. Skylab falling).

Experience with news media hype and misinformation suggests we need more science literacy among journalists and citizens in general.

Two-Tiered Approach to Dealing with Irrational Risk Responses

Public officials must be prepared to deal with disproportionate responses The public politically demands that they do There are real psychological, economic, and other

consequences

Politicians, educators, and science journalists must endeavor to teach citizens how to evaluate more rationally the risks that affect them Generally, fear would be reduced; rational concern

would lead to constructive response Our national and personal resources would be

employed more cost-effectively