I thought about the concept of making liquid mirror telescopes years ago, thinking mercury would be a good material to start with (without actually studing it’s material properties such as the basic phase diagram) and that the telescope would need to be space-based due to the effects of gravity. Well, looks like I’m not crazy and other people have had the same idea, though mercury may not work in space. And the moon could potentially serve as the base of operations for a gigantic liquid mirror telescope. Pretty cool. Though I’d like to see how they: (1) transport the required quantities of the liquid from the Earth to the moon for such a huge instrument, and (2) deal with the lunar dust problem - i.e., keep the liquid free of the contaminating lunar dust.