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Scientists are keeping a close eye on a big asteroid that may pose an impact threat to Earth in a few decades.
The space rock, which is called 2011 AG5, is about 460 feet (140 meters) wide. It may come close enough to Earth in 2040 that some researchers are calling for a discussion about how to deflect it. The object was discovered in January 2011 by Mount Lemmon Survey observers in Tucson, Ariz. While scientists have a good bead on the space rock’s size, its mass and compositional makeup are unknown at present. The near-Earth asteroid 2011 AG5 currently has an impact probability of 1 in 625 for February 5, 2040, said Donald Yeomans, head of the Near-Earth Object Observations Program at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. This impact probability isn’t set in stone, however. So far, researchers have been able to watch the asteroid for just a short time, the first nine months of 2011, and the numbers may change after further observation. 2011 AG5 may zip through such a keyhole on its close approach to Earth in February 2023, which will bring the asteroid within 0.02 astronomical units (1.86 million miles, or 2.99 million kilometers) of Earth. According to a JPL estimate, the 2023 keyhole, through which 2011 AG5 must pass in order for there to be a real chance of an Earth impact in 2040, is roughly 62 miles (100 km) wide. NASA Administrator Charles Bolden said that 2011 AG5 is high on NASA’s list of NEOs to monitor for impact hazard potential, adding that they take these duties very seriously. Bolden also noted the opportunities for highly accurate ground-based observations in the near future. Based on these observations, a more informed assessment can then be made on the need for any type of mitigation. Bolden also remarked that the asteroid makes an apparition in 2015, more than seven years before the close keyhole passage in 2023 that could set in motion an Earth impact in the 2040 time frame.