From New Scientist: Asteroid bound for Earth! Warn your grandchildren
So, this 560m-diameter meteor has a 1-in-1400 chance of hitting earth in the last three decades next century. I won't know, because I doubt I'll be alive between 2169 and 2199. But it's said that if "they" (whoever they is) decide to send something to it to knock it off course, the best time would between 2060 and 2080, when the meteor'll be making close passes to Earth. And I really really hope I'm alive 50 years from now, because that would be something to see!