I have heard justifications for going back to the moon, including setting up a manned scientific base, but usually the justification is as a stepping stone for sending some humans to Mars. This is actually ridiculous. At this stage in human history, sending humans to the moon or Mars is a complete waste of massive amounts of precious resources, and generates a huge carbon footprint here on Earth. We should continue some scientific investigation of the Cosmos using telescopes, probes and robots, but we do not need any more humans in space. Can NASA run a massive space program using only wind and solar power? If not, what are we thinking?