President Bush is having NASA go back to the moon before Mars. Why is that necessary?
It is not necessary. It is prudent. We could try to go to Mars directly, but we would be more successful if we had the chance to rehearse. We would have the experience behind us. Not 40 years behind us but immediately behind us. Does this mean colonization of the moon? It means explorers go there, then leave once they learn what they need to learn, and the science people leave when they get what they need. Then the facilities could be turned over to commercial activities. That would initially involve people, but the moon is not a very habitable place. Robotic devices should be able to continue to operate without people. Unless we are sending humans beyond Earth orbit, it is hard to justify why the humans are there unless they want to be there for the experience: adventure travelers, global space travelers—you might call them tourists.
