re: Build astronomical observatories where it makes sense for the application
My thinking since 1997 has been that impact astronomy is the only lunar based astronomy that would be worth the cost.
For NEAs, the small carbonaceous chodrites are too dark to pick up with a passive system - you have to have either radar or lidar. The large power requirements for either pretty much entail the use of the Moon.
For NECs, you get an extrar 6 months using the Moon, if it can be used. Given our current propulsion and diversion technologies, those 6 months could be critical - minimally, those sixth months give mankind a second shot, in case man screws up his first shot.
"That's one small screw-up for a man, one gient f*up for mankind"