Trans-lunar space tug and the International Space Station

A trans-lunar space tug departs the International Space Station (ISS) in preparation for retrieving a lunar lander currently in Earth orbit. What might be mistaken for wings are in fact solar voltaic panels for converting sunlight into electricity, just like those that bedizen the ISS. Over two hundred miles below is the Atlantic ocean, the Canary Islands, and the west coast of Saharan Africa. Long clouds of dust can be seen blowing westward off Morocco.

If lunar exploration becomes a regular activity, it may become cost-effective to place a dedicated space tug into permanent orbit. Such a craft could serve the same purpose as the Apollo Command Modules did in the 1970s--ferrying astronauts and lunar landers between Earth orbit and lunar orbit--with the exception that this space tug could make the trip multiple times.