HR: 09:35h
AN: P51E-02 INVITED     [PDF]
TI: A Study to Determine the Feasibility of Extending the Search for NEOs to Smaller Limiting Diameters: Report of a NASA Science Definition Team
AU: * Stokes, G H
EM: stokes@ll.mit.edu
AF: MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420-9185 United States
AU: Yeomans, D K
EM: Donald.K.Yeomans@jpl.nasa.gov
AF: NASA JPL, 4800 Oak Grove Drive MS 301-150, Pasadena, CA 91109-8099 United States
AB: In 1998, NASA formally commenced efforts toward the goal of finding and determining the orbits of at least 90% of all near-Earth asteroids with diameters 1 Km or larger by 2008. The 1 km diameter metric was chosen after considerable study indicated that an impact of an asteroid greater than 1 km would likely cause a worldwide catastrophe and could potentially result in worldwide damage up to and including extinction of the human race. The NASA commitment has resulted in the funding of several focused asteroid search efforts that are making considerable progress toward the 90% by 2008 goal. To date, more than 50% of the expected population of these large asteroids capable of passing near the Earth has been discovered and the discoveries continue at a high rate. While the current goal covers the larger objects, which could cause global devastation, it is silent on the much more numerous smaller objects (between 50 meters and 1 km diameter) that could cause local or regional damage should they impact. Given the significantly larger population of Near Earth Asteroids (NEAs) with decreasing diameter, it is much more likely that civilization will experience the impact of an asteroid smaller than 1 km than a larger event. In addition, the public and the science community are beginning to see more information on objects with smaller diameters. Because the current asteroid survey programs are designed to find the "large" threatening objects, they now search a large enough portion of the sky each month that many smaller objects are found as well. These detections are expected, and should be viewed as an indication of the increasing capabilities of the search programs; however, in some cases the discoveries have been interpreted by the press and public as surprising and threatening. Since the existing search programs are making good progress toward meeting the current goal, given the emerging discussion of smaller objects it is natural to ask what, if any, action should be taken to catalogue or warn against potential impacts of objects smaller than 1 km in diameter. From August 2002 to June 2003, NASA commissioned a Science Definition Team to develop an understanding of the threat posed by smaller objects and to assess methods of detecting them and providing warnings of any potential impacts. The Team provided recommendations to NASA and outlined an executable approach to addressing any recommendations made. Specifically, the team was chartered to address the following questions: 1. What are the smallest objects for which the search should be optimized?\\ 2. Should comets be included in any way in the survey?\\ 3. What is technically possible?\\ 4. How would the expanded search be done?\\ 5. What would it cost?\\ 6. How long would the search take?\\ 7. Is there a transition size above which one catalogs all the objects, and below which the design is simply to provide warning? The Team has conducted an in-depth analysis of the asteroid impact hazard and methods for characterizing the risk by discovering and cataloguing the potentially hazardous asteroid population. A cost/benefit approach was used to analyze the effectiveness of a broad range of search methods and technology and to provide answers to the seven specific questions stated above. *This work was sponsored by NASA under Contract F19628-00-C-2002. "Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the United States Government."
DE: 6205 Asteroids and meteoroids
DE: 6297 Instruments and techniques
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting