re: distances
I understand the argument very well, Raoul. It still cost money to launch replacement parts to the moon and have somethingretrieve the broken robot.
The big problem isn't the system won't work on the Moon it is the demands on our knowledge base is vastly higher than our level of engineering can sustain right now. Paul Spudis likes to say Mars is "a bridge to far" meaning it would have a long supply chain. Well building robotic extraction processing machines for the perpetually dark ice areas on the Moon is a technological bridge to far. Ask some robotic engineer if they would care to build a robot that operates in liquid nitrogen and the robot must breakup and grind rock while there.