At t = 446 s after midnight, a spacecraft of mass 1380 kg is located at position (6 x 105, 3 x 105, -8 x 105) m. At that time an asteroid whose mass is 3 x 105 kg is located at position (5 x 105, -6x 105, -14 x 105) m. There are no other objects nearby. (a) Calculate the (vector) force acting on the spacecraft. (b) At t = 446 s, the spacecraft's momentum was p, and at the later time t = 454 s, its momentum was pf. Calculate the (vector) change of momentum p - Pf.