1. The problem statement, all variables and given/known data A 6000 kg lunar lander is in orbit 10 km above the surface of the moon. It needs to move out to a 100 km-high orbit in order to link up with the mother ship that will take the astronauts home. How much work must the thrusters do? 2. Relevant equations U_s = -GMm/r F_g = GMm/r^2 3. The attempt at a solution I tried to calculate the difference in force between the two orbits and then calculate the change in energy to get the work, but I've had no luck.