A moon lander is a spacecraft intended to land on the surface of the moon. When the lander is 15.0 m above the surface, the engine is cut off and has a speed of 1.0 m/s in the downward direction. Also, when the engine is off, the lander is freely falling under the gravity of the moon. What is the landing speed of the lander just before it reaches the surface? Consider the acceleration due to gravity on the surface of the moon as 1.6 m/s².