Bruce Betts reports from the Planetary Defense Conference in Romania
75% of one-kilometer-diameter asteroids have been discovered and 85% of those larger than a kilometer, a total of 914 objects as of May 1, 2011. About 25% of Apophis-size (about 300 meter) asteroids have been found, and smaller percentages of smaller-sized ones.
IR astronomy and was used in part to find NEOs -- and it sure was successful. From a non-optimized orbit, NEO-WISE, as they called the NEO part of the Wide-field Infrared Survey Explorer, discovered 132 near Earth asteroids.
Anders Sandberg on Mitigating Asteroid Risk
A Space-Based Near-Earth Object Survey Telescope in Support of Human Exploration, Solar System Science, and Planetary Defense
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