I have read this article here and it talks about the delta-v cost of travelling to and from the Moon. Importantly it says that getting to an orbit round the Moon, and docking with a space station, and then going down to the Moon, back to space station, back to Earth, has a very high delta-v compared to a straight Earth-Moon-Earth mission.
Can someone explain to me why that is the case?
The reason I'm wondering is that my (basic) knowledge of space flight says that during the Apollo missions, NASA famously had "the loneliest man in the solar system" left orbiting the Moon, while Neil and Buzz went for a stroll on the Moon. Was the orbit of the orbiting space craft that much different to this Luna space station, that the delta-v was lower for earth-moon orbit-moon-moon orbit-earth trip?