1. It Can’t Happen Now Fallacious complacence about Planetary Defense

2. “This is not an issue that we should worry about in the near term.” – NASA Administrator Charles Bolden, testifying to Congress about the threat of catastrophic impact by an asteroid or a comet (House Science Committee, March 19, 2013, “Threats from space: a review of U.S. government efforts to track and mitigate asteroids and meteors,” hearing video, minute 104:50, http://science.house.gov/hearing/full-committee-hearing- threats-space-meteors-and-comets-part-1)

3. Why Planetary Defense? D/1770 L1 / Comet Lexell – Charles Messier (6 LD on July 1, 1770) Tunguska event, Siberia (June 30, 1908) Barringer Crater, Arizona (Eugene Shoemaker, 1960) Apollo and Mariner missions (1960s-1970s) KT Boundary – Gubbio, iridium (Walter and Luis Alvarez, 1980) Chicxulub Crater, Yucatan (Alan Hildebrand, 1991) D/1993 F2 / Comet Shoemaker-Levy 9 (July, 1994) Chelyabinsk bolide and 367943 Duende/2012 DA14 (February 15, 2013) C/2013 A1 / Comet Siding Spring (1/3 LD from Mars on Oct. 19, 2014)

4. -- Alan Harris, “NEA populations and impact frequency,” NASA Asteroid Grand Challenge Seminar Series, March 28, 2014, http://sservi.nasa.gov/wp-content/uploads/2014/03/Harris.pdf Don’t Panic? The Power Law for NEOs

5. The Power Law

6. Panic! The Fallacies or What’s a philosopher doing talking about planetary defense?

7. Argument from ignorance (claiming to know -x based on not knowing x) “We know everything out there that is that big, and there is just nothing right now that's in an orbit that's any threat toward the Earth.” -- Lindley Johnson, Near-Earth Object Program Executive at NASA, as quoted in Mike Wall 2012, “End may be nigh for asteroid disaster movies,” Space.com, June 21, http://www.space.com/16251-asteroid-impact-disaster-movie-facts.html

8. The clockwork fallacy (interpreting averages as regular occurrences or as predictions) “We thought that humanity would not have to face such an attack for another couple of thousand years, but the opposite happened and Russia was hit with a large-scale natural emergency.” -- Russian Emergency Minister Vladimir Puchkov regarding the lack of preparedness for what took place in Chelyabinsk (RT News 2013)

9. The procrastination fallacy (The small likelihood of a harm makes it OK to put off dealing with it now) reductio ad absurdum 1.Suppose it were true that the vanishingly small probability of annihilation by an impactor in the near future made it irrational to strive to make adequate preparations to prevent it (since there will always be more pressing priorities). 2.Then there would never be a good reason to make adequate preparations to prevent annihilation by an impactor (until one were detected, but that would likely be too late). 3.But there is certainly a good reason to make adequate preparations to prevent annihilation by an impactor (since it will occur someday unless we prevent it). Ergo: It is not true that the vanishingly small probability of annihilation by an impactor in the near future makes it irrational to strive to make adequate preparations to prevent it.

10. The low-hanging fruit fallacy (dealing with the relatively easy stuff means you can ignore the relatively difficult stuff) Planetary Defense pertains to both asteroids and comets, but defense against the former has completely eclipsed the latter, as attested by the following: name of Congressional hearings on planetary defense: “Threats from Space: A Review of Efforts to Track and Mitigate Asteroids and Meteors” name of UN planetary defense initiative: “International Asteroid Warning Network” name of White House/NASA planetary defense Grand Challenge: “Asteroid Initiative” logo slogan of B612, the premier NGO for planetary defense: “Defending Earth Against Asteroids” logo slogan of the biennial planetary defense conference: “Protecting Earth from Asteroids” name of the new annual planetary defense awareness day: “Asteroid Day”

11. Equivocation (trading on the ambiguity of a term) Treating risk as if it were just probability “The risk of a catastrophic impact is very low.” vs. Risk = probability x magnitude of the feared outcome “Impactors pose a big risk (even though the likelihood of one hitting us is low).” “Although the annual probability of the Earth being struck by a large asteroid or comet is extremely small, the consequences of such a collision are so catastrophic that it is prudent to assess the nature of the threat and to prepare to deal with it.” -- David Morrison (ed.) 1992, The Spaceguard survey: report of the NASA International near- Earth-object detection workshop, NASA/Jet Propulsion Laboratory/California Institute of Technology.

12. Contradiction “Unless a large flotilla (100 or more) of massive spacecraft was sent as impactors, nuclear explosions are the only current, practical means for changing the orbit of large NEOs (diameters greater than about 1 km). They also remain as a backup strategy for somewhat smaller objects if other methods have failed. They may be the only method for dealing with smaller objects when warning time is short ….” -- National Research Council 2010, Defending planet Earth: near-Earth object surveys and hazard mitigation strategies, National Academies Press, Washington, D.C., http://www.nap.edu/catalog/12842.html “No sensible argument has been put forward for using nuclear weapons to solve any of the major 21st century problems we face ….” -- Global Zero Commission 2012, Modernizing U.S. nuclear strategy, force structure and posture, http://dl.dropbox.com/u/6395109/GZ%20US%20Nuclear%20Policy%20Commission%20Report. pdf; co-signed by former U.S. Senator Chuck Hagel just before he became Secretary of Defence.

13. Improper transposition (mistaking a necessary condition for a sufficient condition) “[Planetary scientist Donald ] Yeomans … insists that the three most important things to do are ‘find ’em early, find ’em early, and find ’em early’.” -- Andrew Lawler, “What To Do Before the Asteroid Strikes,” Discover magazine, November 2007, http://discovermagazine.com/2007/nov/the-asteroid

14. False dichotomy “… most people continue to drive their automobiles regardless [of there being “31 million accidents … per year, at an annual cost of almost $100 billion”]. For the same reason, that we can't live our lives paralyzed by the fear that something bad may happen, we shouldn't let the remote possibility of being struck by a meteor or asteroid rule our lives.” -- NASA 1998, “Is Earth in danger of being hit by an asteroid?” Ask an Astrophysicist blog, http://teacherlink.ed.usu.edu/tlnasa/reference/imaginedvd/files/imagine/docs/ask_astro/answ ers/danger.html

15. Conclusion and recommendation: A principle of planetary defense Act on the assumption that the next large object targeting Earth will be discovered the day after we have prepared an adequate defense against it were we to begin to prepare in all earnestness today. This further implies: 1.A deflection infrastructure must be in place prior to detection of a threatening object. 2.The scope of detection efforts must be expanded beyond near-Earth ever further into the outer solar system and maintained indefinitely. Any less robust planetary defense policy strikes me as irrational and potentially fatal to the human race.

16. Joel Marks Professor Emeritus of Philosophy University of New Haven jmarks@newhaven.edu