I think we have reversed the symbolic meaning of a Manhattan project and a moonshot.
The former has come to mean a large, focus, and dedicated commitment to rapidly addressing a challenging but solvable problem. The second has come to mean trying to do something so fantastic it seems impossible.
But, he writes:
The reality was largely the opposite. Building an atomic bomb was an incredible goal that required significant advances in our understanding of the underlying scientific principles. Getting to the moon was mainly a question of committing ourselves to spending a nontrivial chunk of our GDP on an undertaking that was hugely ambitious in terms of scale but which relied on technology that was already well-established by the beginning of the Sixties.