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Defending Planet Earth: Near-Earth-Object Surveys and Hazard Mitigation Strategies
(12.5 magnitudes) fainter than can be seen with the naked eye. The project, funded by NASA, began in 1993 and was concluded at the end of February 2008. LONEOS discovered 288 NEOs.
The Near-Earth Asteroid Tracking Program began in 1995 and was initially a collaborative effort among NASA, the Jet Propulsion Laboratory, and the U.S. Air Force. This program originally converted a Ground-based Electro-Optical Deep Space Survey (GEODSS) 1-meter-diameter telescope on Haleakala, Maui, Hawaii, to the world’s first fully automated asteroid-search telescope. Operations on the GEODSS telescope ended in 1999. In 2000, the NEAT program completed both the conversion of the Maui Space Surveillance System 1.2-meter-diameter telescope on Haleakala, and the conversion of the 1.2-meter-diameter Oschin telescope at Mount Palomar, California, to become fully automated and to search for NEOs. NEAT ceased operations in 2007 after detecting over approximately 20,000 objects, about 430 of which were NEOs.
PRESENT NEAR-EARTH-OBJECT DISCOVERY EFFORTS
In 2005, five NEO detection programs were operational: Catalina Sky Survey (CSS); the Lincoln Near-Earth Asteroid Research (LINEAR) program; and Spacewatch, as well as LONEOS and NEAT. Today, only CSS, the LINEAR program, and Spacewatch remain operational. These three NEO detection programs primarily address the congressional charge to detect 90 percent of NEOs down to 1 kilometer in diameter.
Catalina Sky Survey
Of the three search programs currently in operation, the CSS discovers NEOs at the highest rate. CSS is a system of three telescopes, located at the Mount Lemmon Observatory in Arizona, the Catalina Observatory also in Arizona, and the Siding Spring Observatory in Australia (all funded by NASA). The Mount Lemmon Observatory is the largest and most productive of these telescopes, having a 1.5-meter-diameter mirror and 1.2-square-degree field of view, enabling it to detect asteroids as faint as M = 22 (i.e., 22nd absolute magnitude in the visual band; see Appendix E). The Siding Spring facility has a 0.5-meter-diameter telescope for discovery. The Catalina Observatory houses the original CSS telescope, which has a 0.7-meter-diameter mirror. These telescopes work together to carry out sustained, highly productive searches for NEOs. Because two of these observatories are operating on the opposite side of Earth from the third, same-night follow-up on a newly discovered object can usually be accomplished, facilitating the rapid determination of its orbit and thus an evaluation of the hazard posed by the object. Indeed, this follow-up technique allowed the CSS to both discover the asteroid 2008 TC3, and to determine that it would impact the Sudan within 19 hours. In analyzing observations, the CSS employs a human operator who can spot faint moving objects that current versions of automated software may miss. The CSS has discovered more than 2,400 NEOs.
Lincoln Near Earth Asteroid Research Program
The LINEAR program at the Massachusetts Institute of Technology Lincoln Laboratory is funded by the U.S. Air Force and NASA and was the most successful NEO search program from 1997 until 2004. The goal of LINEAR is to demonstrate the application of technology originally developed for the surveillance of Earth-orbiting satellites to the discovering and cataloguing of NEOs. LINEAR consists of a pair of GEODSS telescopes at the Lincoln Laboratory’s Experimental Test Site at White Sands Missile Range in Socorro, New Mexico. These two 1-meter-diameter telescopes were eventually joined by a third telescope used for the confirmation of NEO orbits and were able to detect asteroids as faint as M = 20. LINEAR has discovered 2,210 NEOs and accounted for more than 50 percent of all NEO discoveries from 1998 to 2004. In 2005, the rate of discoveries by the Catalina Sky Survey increased substantially and overtook that of LINEAR.