Imagine a landing craft approaching the surface of Callisto, one of Jupiter's moons. If the engine provides an upward force (thrust) of 2760 N, the craft descends at constant speed; if the engine provides only 1863 N, the craft accelerates downward at 0.39 m/s2. What is the weight of the landing craft in the vicinity of Callisto's surface? What is the mass of the craft? (c) What is the free-fall acceleration near the surface of Callisto?