It is possible to communicate between points on earth by usingthe moon as a passive reflector. In fact, it is done routinely by radio amateurs.
1) Calculate the time delay and round-trip path loss at 1 GHz using the moon as a reflector. (The distance to the moon is calculated in problem
2.) Note that your path loss calculation ignores losses in the reflection at the moon's surface. What can you conclude about the likely commercial possibilities of this idea?