Clark R. Chapman Southwest Research Institute Boulder, Colorado, USA

1. http://www.boulder.swri.edu/clark/clark.html THE NEO HAZARD: Interfaces between Scientists and the Public Clark R. Chapman Southwest Research Institute Boulder, Colorado, USA Planetary Defense Conference: Protecting Earth from Asteroids The George Washington University Washington D.C. 7 March 2007

2. Growing Awareness of the NEO Impact Hazard The Little Prince • Generalized fears of comets for centuries (e.g. Halley’s comet in 1910) • Dawning scientific awareness (1940s – 1970s) • NEAs can make lunar-like craters on Earth • Comet nuclei are dangerous, consolidated bodies • Shoemaker/Meteor Crater/surveys…Mariner spacecraft • M.I.T. Project Icarus: nuke an oncoming asteroid • SciFi books (“Lucifer’s Hammer”), movies (“Meteor”)(1970s) • Scientists study NEO hazard (early 1980s) • Alvarez hypothesis for K-T mass extinctions; Chicxulub • NASA Snowmass Workshop; Spacewatch survey • March 23, 1989 (“Near Miss Day”): Asclepius • Early 1990s: Congressional mandate, NASA Spaceguard and DOE Interception Workshops • 25% of public aware of NEO hazard (Slovic 1993) • Chapman & Morrison Nature paper (2004) Asteroid B612 Meteorite punctured roof in Canon City, CO Meteor Crater Global catastrophe

3. Media Events: “Near Misses” and Predictions of NEA Catastrophes • 1997 XF11: Astronomers goof, issue press release implying 1-in-1000 chance of 2028 impact by 1 km NEA; headlines around the world; prediscovery data soon rule out impact. But the chances for impact were always negligible. • 1999 AN10: CCNet internet digest host discovers paper on academic website predicting 1-in-million chance of impact of small NEA in 2039; charges “cover-up”. IAU adopts formal process to review published predictions. • 2000 SG344: IAU Technical Review confirms very high 1-in-500 impact probability in 2030 by a very small NEA (actually a spent rocket or lunar ejecta); impact ruled out hours later but IAU didn’t update web page over weekend…so astronomers looked foolish. (It still could hit, probably harmlessly, in 2070s.) • 2002 MN: Small NEA passed 1/3rd distance to Moon 3 days before discovery. Media claims failure. Actually it was found and is not on an Earth-impact trajectory. • 2002 NT7: Tiny impact probability (1-in-100,000) 17 years hence by 2 km NEA. BBC erroneously reports that it “is on a collision course with Earth.” • 2003 QQ47: British NEO Info. Centre issues press release, causing international scare, despite 1-in-million odds.

4. AL00667: Could it Hit “Tomorrow”? • 13 Jan. 2004: Semi-automatic post on IAU Minor Planet Center website implies small NEA (just discovered by LINEAR) may strike the very next day (the day President Bush is giving his ‘Vision’ space policy speech). • Urgent “Monte Carlo” statistical analysis by MPC and JPL astronomers suggest 10% - 25% chance of Northern Hemisphere impact in next 3 days! (Object estimated ~30m in size = 2MT.) • By midnight, attempts to follow-up clouded out. • Should NASA/IAU astronomers warn anyone? • Later that night, amateur astronomer Brian Warner cannot see AL00667 at location in sky where it would be if it were to hit. Whew! • Two days later, new data show AL00667 is really 10 times bigger but 10 times farther away than it seemed; soon passed by harmlessly. LINEAR search telescope, New Mexico

5. The Torino Scale (to communicate seriousness of predicted NEO impacts) • Astronomers tried to learn from other risk communicators and developed a color-coded scale. • Official scale: the words (for TS = 0 – 10, 1 dimension) • TS is a simplification of the Palermo Scale, based on energy, probability, how far in future (3 dimensions). • Designed pedagogically to illustrate unlikelihood of catastrophe: nearly all cases would be TS=0 or TS=1. • Adopted by IAU in 1999, used by most news media. • Homeland Security Terrorism scale became a joke. • Behind-the-scenes arguments about T.S., but it’s OK. • Then in Dec. 2004 Apophis blew it away: TS = 4!

6. 2004 MN4 (aka “Apophis”) • On Dec. 23rd, JPL and Univ. of Pisa, announce that this NEA (recovered Dec. 18th after being found, then lost, in June) has 1-in-200 chance of hitting Earth on 13 April 2029 with force of thousands of megatons: first ever TS = 2! • As of 27 Dec., new observations over holidays raise impact chances to 1-in-37: TS = 4!!! • Uncertainty in object’s size could mean TS = 5, or 7. • Earlier Spacewatch images found (unlikely!) and analyzed on 28 Dec.: it will miss by 5 Earth diameters. • Month later, Arecibo radar shows that Spacewatch positions are wrong: Apophis will miss by just 5 Earth radii, under geosynch. communications satellites. • If Apophis passes through small “keyholes” (1-in-several-thousand chance), could return to impact later in 2030s. (This chance now reduced to 1-in-45,000.) • Media frenzy averted by holidays, Indian Ocean tsunami. But many “what if’s” and other issues… Kitt Peak National Observatory Arecibo radar in Puerto Rico

7. Issues Raised by Apophis • Flip-flop from 5 Earth diameters to 5 Earth radii illustrates that astronomers often under-estimate uncertainties in data…reduces public trust in science. • Torino Scale wording said that future observations would almost certainly soon push the impact probability to zero: • But then the probability kept increasing for several days (for reasons now understood, discussed on Monday) • Were it not for “lucky” Spacewatch pre-discovery images and “lucky” detection by soon-to-be-closed Arecibo, Apophis might have hung on at high TS values for many months • TS values higher than 2 were never expected; the near miss by something this large that will happen in 2029 (go see it from Europe!) is a 1-in-1,000 years event. • Keyholes/resonant returns are common; they may require immediate planning for early deflection mission to prevent a much later catastrophe. • Where would Apophis hit? How much should be announced to the public, and when?

8. To Tell or Not to Tell… Population Density • In the 1-chance-in-37 that it would hit, extreme destruction would occur within the zone between the dashed lines, somewhere along the solid red line. • You can hardly imagine a line cross- ing more densely populated areas. There was hot debate about whether to release the possible impact points after they were calculated on Dec. 24th. Some argued we should wait for perhaps a year. What do you think should have been done, if MN4 had hung on at TS=4 for months?

9. Risk Management Experts Say: Put it all Out There • Covello’s (1988) 4th Cardinal Rule for Risk Communication to Build Trust and Credibility: “Be honest, frank, and open. Disclose risk info ASAP; if in doubt, lean toward sharing more info, not less.” • Regarding the tension between providing accurate info and providing it quickly: to wait for all info to be complete and verified before release “can create an info vacuum that will be filled with rumor and speculation” (US Dept HHS R.C. Guidelines, 2002). • Sandman’s (2003, US CDC) bad reasons for delaying information: • “The information hasn’t been quality controlled yet” • “People will misunderstand the info, think the threat is worse than it is” • “People might panic if we told them the truth” • US Nuclear Reg. Comm. Guidelines for External Risk Communication (2004) concerning holding back info because preliminary con-clusions may be contradicted by further analysis: “Communicate early and often…failure [to do so] breeds mistrust and gives others the opportunity to frame the issues.”

10. Be Skeptical of the Improbable…but Think about our Purpose • If we find that a very improbable thing is happening (e.g. a new NEA may hit tomorrow or we have a TS=7 event), the best guess is that there’s been a mistake. It is more likely that we human beings erred than that Nature has thrown us yet another Apophis. Very likely, the NEA is really smaller than we estimate, or there’s some mistake in the positions or analysis… • Should we then take a very conservative position, assume there’s been a mistake and wait for it to be corrected before alerting the public? That’s prudent, but… • Consider our purpose: it is to find what we already know is a very unlikely event and alert the public that it actually may happen. If we won’t do that, we should close up shop right now. Should a tsunami warning in the Atlantic be withheld because it is very unlikely for such a tsunami to happen? Quite the contrary. Better be safe than sorry. If the NEA actually hits and we didn’t warn, then we failed in our purpose and we have a giant scandal on our hands. • But, then, if there are too many false alarms (“mistakes”), the public loses trust, ignores warnings, cancels funding. One person injured by an impact is this woman, struck and bruised by a meteorite in her home in 1954. Asteroid impacts do happen and can be harmful.

11. 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 + huge consequences are extremely difficult for people to relate to (e.g. building in 100-year floodplains…or, flip-side, they play the lottery, hoping to win, even though really it’s another dreaded tax). • 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 is falling,” or post-9/11 fears of terrorism). • Scientific/mathematical illiteracy prevails among the public, TV “meteorologists”, journalists, and govt. officials…even among scientists/engineers outside their specialties. Odds of a “Royal Flush” (1 in 649,739) are like chances of a 1.5 km-wide asteroid striking next year!

12. How Important is NEO Threat? We’ve Many Other Things to Worry About! Source: John Pike 9/11 Source: John Pike NEO impact similar to this Mortality from Twentieth Century Catastrophes

13. Chances of Dying from Selected Causes (for U.S.A.)(Chapman/Morrison 1994) Reduced risk thanks to Spaceguard since 1998 By terrorism (much due to Sept. 11th) 9/11

14. Common Misperceptions • Long waiting time until next impact • instead, we should think of chancesof disaster and our responsibilities “on our watch” • Judging consequences quantitatively • civilization-ending impact vs. K/T mass-extinction • “one death” vs. 100 deaths/yr vs. 3000 9/11 dead vs. we will all die in next 100 years (what are our values?) • Shoemaker-Levy 9 Jupiter impacts overshadowed the Rwanda genocide in the news (July 1994) • “Blow it up” on the way in • movies misrepresent reality of decades lead-time • NEA is “on an impact course with Earth” • NEA discovery process, error ellipses, NEA orbits the Sun many times before impact: not intuitive! Part of very elongated error ellipse

15. How Well do we Plan for and Respond to Other Disasters? Guatemala, Hurricane Stan Hurricane Katrina Indian Ocean Tsunami Kashmir Earthquake

16. Practicalities, Perceptions, and Politics LINEAR, New Mexico • Spaceguard Survey is 3/4ths complete for >1 km asteroids (but won’t reach 90% for many years). • Congress has mandated, but not funded, a search for NEOs >140 meter diameter. • No national/international agency has taken respon-sibility to evaluate and plan for an NEO disaster. • There have been many “studies” but little integration into an “all-hazards” approach to emergency planning, disaster response, or policy development. • “Giggle factor” is mostly gone. The major problem is politics-as-usual (every interest preserving their turf) when budgets are tighter than ever: no “new” funding (except for the “War on Terrorism” and the politics of fear). (Morally, we should not buy-in to the politics of fear, although it might otherwise be the best route to success.) • If they still can’t get Katrina right, how can we expect rational steps concerning our NEO threat: a mid-range potential catastrophe?

17. Some Lessons Learned… or at least some issues to be discussed! • These impact possibilities and near-misses almost always have unexpected attributes (a rocket not an NEA, “came from the Sun,” discovered by uncharacterized telescope, discovered on a weekend or holiday, poorly understood data imply it will hit “tomorrow,”…). We must continue to expect the unexpected. • We must quickly and rigorously search for pre-discovery observations: the public considers it a mistake if we announce a possible impact when we already have data disproving it. • We must use meta-error bars, which take into account not only formal errors, but biases, approximations, Bayesian statistics, etc. • We must continue to re-evaluate and pre-plan our public communications, bring them in line with professional risk-communication guidelines. (For example, Apophis teaches us that the T.S. wording “new telescopic observations very likely will soon lead to re-assignment to TS=0” can be wrong: for several days, the new observa-tions led to higher TS ratings…could have avoided TS=0 for months.) • Our charge: we must act as though the impact will happen, even as we say that the chances are small (unless the threat is truly negligible).