The space probe Deep Space 1 was launched on October 24, 1998. Its mass was 474 kg. The goal of the mission was to test a new kind of engine called an ion propulsion drive. This engine generates only a weak thrust, but it can do so over long periods of time with the consumption of only small amounts of fuel. The mission has been spectacularly successful. At a thrust of 56.0 mN how many days are required for the probe to attain a velocity of 830 m/s, assuming that the probe starts from rest and that the mass remains nearly constant?