Clark R. Chapman Rusty Schweickart B612 Foundation

1. Clark R. Chapman Rusty Schweickart B612 Foundation NEO Mitigation and Coordination with the Disaster Management Community “1st IAA Planetary Defense Conference” Granada, Spain 15:30 29 April 2009

2. From Telescopic Discovery to Effective Emergency Management • Currently, if a threatening NEO is discovered, there is inadequate infrastructure to evaluate the threat and communicate it effectively to any relevant national or international emergency management agency. • Pieces are in place (e.g. JPL Sentry, NEODys, IAU MPC, UK NEO Information Centre, etc.) but they have narrowly defined roles: • organizing NEO observers • calculating orbits and predicting impacts • maintaining NEO news websites • NASA has a formal structure for observers to notify Lindley Johnson, Johnson to notify NASA, and NASA to notify US Executive Branch. • But it is doubtful that FEMA/DHS in U.S. or any other national/international emergency management agency would know what to do in response to notification. • We will show that the need to establish such linkages between astronomers and those who would respond to a threat is more urgent than had been thought.

3. Understand the Power-Law:Small Ones Happen Much More Often • We think about the big ones, which might threaten civilization…and we should. • But the most likely kind of event that politicians, officials, and the public will have to deal with are the smallest predicted impacts that might be dangerous (Spacelab’s re-entry in 1979 was an extreme example). • Past PDC’s have studied scenarios focused on Apophis and other “templates” for probable impacts, which are far larger NEAs and more unlikely than the overwhelmingly most likely event to confront officials. • For every Apophis, there are more than 50 Tunguskas, and ~1000 impacts by 15 m NEOs that might compel officials to act.

4. What is the Smallest NEO that is Dangerous? Model of 30 m NEA 1998 KY26 (radar) This will be a vital issue for decision-makers • Metallic objects are not impeded much by the atmosphere, whatever their size; they create most craters <1 km diam. but are only ~3% of NEOs. • The 2003 SDT report considered ~50 m diameter to be the smallest truly dangerous non-metallic NEO. • Some analyses (e.g. Boslough’s study of Tunguska) suggest that the threshold for danger is near 30 – 40 m. • Should we then be unconcerned about deflection/ evacuation for a 25 m body? They impact ~10 times as often as 50 m impactors. • A nominal 25 m body may actually be 50 m in diameter (because of bimodal albedo distribution). • What will public officials do about a predicted impact by a 15 m NEO? Be “safe not sorry” and evacuate! (They impact ~30 times as often as 50 m impactors, 20% chance this decade.) ? LSST: 15 m NEO?

5. Short-Term Warning: the New Reality • There is better than 1-chance-in-3 that the Spaceguard Survey will provide short-term warning (few weeks) for any potentially dangerous impact during the next decade! • Previously it was said that the Survey would provide “decades of warning” for threatening NEOs found, but that the Survey would miss the vast majority of Tunguskas and we would first learn of such an impact by the flash and explosion. • The recent case of NEA 2008 TC3 teaches us that we have a much better early-warning system than we thought. • Since astronomers can provide early warning, communications channels with emergency managers must be established.

6. 2008 TC3: Some Background • NEA discovered 7 Oct. 2008, predicted to impact Sudan 20 hours later. • Before impact, other telescopes observed TC3’s physical properties. • Nearly 300 pieces of rare ureilite meteorites recovered. • TC3 was ~4 meters diameter, roughly an annual impact on Earth. • Spaceguard Survey was expected to find only 1-in-1 million TC3-sized NEOs. • Was it a miracle that we found beforehand what was plausibly the largest NEA to impact Earth in 2008? • NO! Astronomers overlooked Spaceguard’s short-term warning capability.

7. Short-Term Warning Capabilities of NEO Surveys • Current Spaceguard Survey will find ~35% of NEAs >30 m diameter on “final plunge”; could be improved to ~50% or better. • It is ~100 times more likely that the Spaceguard Survey will find a >30 m impactor on its final plunge than that it will find one long in advance that will eventually hit. • Next generation survey (LSST, Pan-STARRS) will find ~35% of impactors >2 m diameter; for >30 m NEAs, there are similar chances for: • Short-term warning • Long-term warning • No warning at all • Short-term warning was not studied for current Survey; SDT (2003) did study short-term warning for next generation surveys.

8. Public Officials Must Make Decisions Much More Often than NEOs will Hit Low Probability Impact: What is the Threshold for Action? 20%? 5%? • Post-disaster rescue and recovery if NEO strikes undetected. • Warnings for evacuation, disaster-preparedness if there is a short-term warning. • Preparing for a low-probability chance that a “virtual impactor” proves to be about to strike. • Preparing for Apophis-like scenarios: decisions to launch a pre-deflection mission (e.g. transponder with Gravity Tractor capability) must be made long before keyhole passage, perhaps very long before the threatened impact. • Evaluation of marginal impact scenarios: • Predicted impact by NEO ~15 m diameter: just watch the fireworks or be prudent? • Immature or spurious impact warnings See next chart

9. Example: Virtual Impactor Search Palmer Divide Observatory • At any time, there are numerous low-probability impacts listed on the JPL Sentry Risk website. • In some cases, the NEA may not be observable again until its possible “final plunge”. • The approach would be to search telescopically for the “virtual impactors” that would strike the Earth during the weeks prior to impact. • If the NEA is coming from the general direction of the Sun, radar would be required to search for the possibly incoming NEA (warning might be only a couple of days). • If the chance for impact were high enough (how high?) then public officials (responsible for localities in the “risk corridor”) should give forethought to emergency management preparations. Note: the “risk corridor” of possible impact points will be well known. • If the NEA is on an impacting course, then the preparations must be implemented quickly. Arecibo

10. Relative Frequency of NEO Event-Types and Required Actions • Hyped or unreliable media news stories. Officials irritated but must do nothing. Annual  more often? • Impact predictions for future decades requiring analysis, but leading to no action. 20%/decade  several per year. • Short-term impact warningfor ~15 m NEA. Immediate evacuation would be prudent.7%/decade  15%/decade. • Prediction of an impact during next 50 years eventually requiring launching of a transponder mission(for NEAs > 100 m). 1% chance  15% chance. • Short-term impact warning for >40 m NEA. Immediate evacuation required (by ships or from ground-zero). 0.3%/decade  1%/decade. • Detection of NEA >100 m that would ultimately impact during next 50 years if deflection isn’t attempted or successful.0.01%  0.2%. • Detection of civilization-threatening NEO that will strike in next 50 years. 0.001%  0.0003% chance.

11. “Mitigation”: What does it mean? • Mitigation means: “lessening unfavorable consequences” (in engineering, economics, environmental impacts, medical field, and – especially – in emergency management) • In Planetary Defense, “mitigation” has been distorted to mean only “deflection” • NASA 2007 report notes broad meaning of “mitigation” but explicitly restricts meaning to “deflection” (not even “fragmentation”) • US Congress has ordered NASA to evaluate NEOs “in order to provide warning and mitigation” for the potential NEO hazard. • Any sensible mitigation plan must include all plausible emergency management methods, including warning and evacuation.

12. What is the Primary Mitigation Approach: Evacuation or Deflection? Both! • Evacuation • Why it is Important… • By far the most likely case we will face • Attributes… • Inexpensive and familiar: apply usual “all hazards” emergency procedures • Requires rapid, reliable communications between astronomers and officials, and famililarity with the issues by emergency managers. • Deflection • Why it is Important… • Only responsible way to prevent global or regional-scale disaster from happening. • Attributes… • Deflection implementation is much less likely than the need to evacuate. • Advance decisions must be made when need to deflect is still not known. • Expensive! Especially if need uncertain.

13. Need to Establish Infrastructure for Evaluation, Warning, Coordination of Emergency Managers • Optical and radar observatories need to develop rapid communications to respond to NEOs before impact. • NASA needs to develop understandings within agencies (those it would warn) about nature of NEA impact warnings so that emergency responses will be appropriate and effective. (Analogous links should be established in other countries.) • Internationally, ASE has recommended establishing under the U.N. an “Information Gathering, Analysis, and Warning Network” (IAWN) to coordinate the integrated end-to-end process from telescopic searching for threatening NEOs through coordination with national and international disaster management agencies. • These needs exist today, but will become crucial as the surveys are upgraded during the next decade.

14. 433 Eros Comet McNaught