Talks at the Recent AAAS Meeting on Apophis

There were several papers on Apophis at the recent 2007 American Association for the Advancement of Science (AAAS) Annual Meeting that took place in San Francisco, CA from 15-19 February 2007. Dr. David Morrison (NASA Astrobiology Institute) moderated a 90 minute symposium entitled: "Apophis Now: Predicting and Avoiding an Asteroid Impact." Here are the selected talks with their respective abstracts:

- "Asteroid Orbits and Collision Probabilities"
(Steven Chesley, Jet Propulsion Laboratory, Pasadena, CA, USA)

- "Apophis and International Policy Implications"
(Russell Schweickart, Association of Space Explorers, Tiburon, CA, USA)

Apophis and International Policy Implications. Apophis is a near-Earth asteroid whose orbital characteristics have forced the astronomical community and those concerned with protection of the Earth from NEO impacts to grapple with complex and subtle issues well beyond what was assumed prior to its discovery. Among the many sobering realizations which soon became apparent was the locus of potential impact points stretching across the face of the planet should the asteroid actually impact Earth on Friday, April 13, 2029. This path of risk (PoR), stretched almost 270 degrees around the Earth passing directly over the UK, across the European heartland, just along the northern border of Turkey, and on across Iran, Afghanistan, Pakistan, India and southeast Asia. There were, at a minimum, 16 nations whose populations were potentially at risk. Were the early probabilities of impact to prevail, the debate over how mitigating actions were to be taken and who was to take them would have been fearsome. The fortunate discovery of a marginal observation of the asteroid nine months prior, and its integration into the orbit determination led to the probability of its 2029 potential impact dropping to zero. Apophis did not totally leave the scene however since its 2029 pass by Earth will be unusually close (within the geostationary orbit) thereby setting up a potential return of the asteroid for a subsequent impact in 2036. In this instance, should the impact occur, the PoR extends from Siberia, down across the Pacific north of Hawaii, skirting the Mexican coastline and crossing Central America along the northern Costa Rican border. After passing down the northeastern South American coastline it passes out into the Atlantic terminating just off the West African coast. In this instance, while the PoR crosses fewer international borders an impact in the Pacific (the most probable circumstance) would result in a Pacific tsunami of historic proportions. This paper examines the sobering international policy implications of the many choices which would confront the world community were Apophis to follow such a course. By analog Apophis is indeed representative of all NEOs which threaten an impact with Earth and for which, in many cases, choices will have to be made prior to the time that an impact is certain. The paper will argue that the United Nations is the appropriate international institution that must confront these choices and that it is highly likely that such choices will have to be made prior to 2020 due to the acceleration anticipated in the NEO discovery rate.

- "Asteroid Deflection Options: Limitations and Implications"
(Edward Lu, NASA Johnson Space Center, Houston, TX, USA)

Abstract: Asteroid Deflection: The Cosmic Do No Harm Principle. We argue that an important consideration when faced with the prospect of deflecting a threatening asteroid is the “Cosmic Do No Harm Principle”, which states that non-controllable or non-predictable deflection methods are to be avoided if possible. The case of asteroid Apophis offers a good illustration. Two proposed deflection methods, kinetic impactors and nuclear bombs, violate this principle since we cannot be certain that they will not fracture the asteroid or put it through a different collision keyhole with Earth, and therefore worsen the situation. Since the deflection velocity in this case is very small, a much better option is a Gravitational Tractor which can controllably steer Apophis away from an impact keyhole with Earth.

- "Asteroid Impacts and Public Responses to Low Probability Threats"
(Paul Slovic, Decision Research, Eugene, OR, USA)

Link: AAAS Annual Meeting