Uhhh, and what side of the moon would that be? That's like saying "the dark side of the Earth." It's the side away from the Sun - but if we wait a little while, it'll swap places with the lit side of the Earth. The same side of the moon always faces the Earth. When we see the full moon, that side is lit. Roughly half a month later, during a new moon, the opposite side is completely lit, and the side facing us is dark.
There are a lot of better places to put space telescopes, such as the stable Lagrangian points.