The Space Review article and B-612 Foundation Paper
While the asteroid poses no impact threat to the Earth in 2029, it will pass within about 30,000 kilometers of the planet—closer than satellites in geosynchronous orbit. That passage will be close enough to allow the Earth’s gravity to significantly alter the asteroid’s orbit. The change in the asteroid’s orbit will depend on exactly how close to the Earth 2004 MN4 approaches, a degree of precision not yet possible with the currently-known orbit of the object.
http://www.thespacereview.com/article/384/1
B-612 Foundation Paper:
http://www.b612foundation.org/papers/Call_for_Action.pdf