2012DA14 was discovered by astronomers at the La Sagra Sky Survey program in the South of Spain, who reported it the Minor Planet Center. At that time the passage was 7 times the distance to the moon. They calculated the orbit to be at about 368 days. It passes, they explained, every year. This passage, in 2013 will be the closest yet, giving astronomers at NASA's Goldstone Radar in the Mojave Desert an opportunity to study the object for factors such as size, spin, and reflectivity. The pass in February will alter the orbital period to about 317 days, and any future close approaches will follow a different pattern. The asteroid will not make another close approach for at least 3 decades.
Yeomans mentions that “The odds of an impact with a satellite are extremely remote; nothing orbits where DA14 will pass."