At a time when mining asteroids has become feasible, astronauts have connected a line between?

At a time when mining asteroids has become feasible, astronauts have connected a line between their 3390-kg space tug and a 6240-kg asteroid. They pull on the asteroid with a force of 690 N. Initially the tug and the asteroid are at rest, 550 m apart. How much time does it take for the ship and the asteroid to meet?