I just captured a class B asteroid that was headed straight for Kerbin. I actually left Kerbin SOI by matching the inclination of the asteroid then using a maneuver node to get within 10km. The asteroid had about 30 days before it entered Kerbin's SOI so I had plenty of time to approach the asteroid and grab on. My next goal is it get it into orbit of Ike. Those Fine Print contracts are sure entertaining.