re: 4 Approaches for Return to the Moon
"(over 30 years and counting since folks walked the moon)"
A serious point. I will consider it an enormous failure of the human species if we get to the point where none of the Apollo moonwalkers are still alive, and we are yet to 'go back'.
If you had asked any one of them at the time if they thought they'd be alive to see a man walk on mars - they'd have all said yes 100%. That's looking further away now than ever before. If you'd have suggested that they would all be dead before man walked on the moon again - they'd have laughted at you.
Doug