Farside Communication

Communications between the Earth and the farside of the Moon is challenging, and currently impossible, because there is no line of sight between the Earth and the far side.

Optical Fiber Cables

One option would be to install a large fiber optic cable across the lunar surface to a repeater station on the lunar limb.

Chain of Microwave Towers

Communications relay satellites

There are various proposals for communications relay satellites, but it is a difficult problem to solve. Earth has geostationary satellites which are in stable orbits, hovering constantly over a point on the Earth's surface. Unfortunately, unlike Earth, the Moon has no equivalent of geosynchronous orbits.

There are basically two options for farside relay satellites.

Option 1) Located at Lagrange Libration points

The problem here is that the Lagrange points are many tens of thousands of kilometers from the lunar surface, which results in large space attenuation, adversely affecting the respective link budget, and introducing more round trip time delays.