The space probe is traveling in outer space with a momentum which consists of a magnitude of 7.20 107 kg • m/s. A retrorocket is fired to slow down the probe. This exerts a force to the probe which consists of a magnitude of 2.10 x 106 N and a direction opposite to the probe's motion. It fires for a period of 10 s. Find out the momentum of the probe after the retro-rocket ceases to fire.