A private space technology company aims to land its rocket (m = 5.49× 10⁵kg) back on Earth in an upright position after its mission into space orbit. However, when the rocket was 3 × 10⁴ km from Earth, one of its engines failed due to a malfunction, and it started falling back at a rate of 15 km/s. Ignoring the earth's gravitational force on the rocket, determine when the rocket will crash on the earth.