A spaceship is visiting Planet X. While descending to the surface,its rockets produce 25 kN of upward thrust and the spaceship%u2019s speed decreases at a rate of 0.15 m/s2 . Following the completion of its mission, the spaceship lifts off to return to its home planet. While leaving Planet X%u2019s surface, the rockets produce 75 kN of upward thrust and the spaceship%u2019s speed increases at a rate of 0.50 m/s2. What is the mass of the spaceship and the acceleration due to gravity at the surface of Planet X? Assume that the acceleration due to gravity is constant.