Fifty years after Apollo, when will we go back to the moon?

Fifty years ago, Neil Armstrong's famous first steps on the surface of the moon demonstrated both ground-breaking technical expertise and immense political will. Science and technology have made considerable progress since then, so why was the last manned mission to the moon in 1972? In his new book, Returning People to the Moon After Apollo, former Apollo engineer Pat Norris gives a detailed account of the Apollo missions and of the Soviet program that was the other competitor in the race to th...