Man Who Sold the Moon / Orphans of the Sky

From the back cover:

The Man Who Sold The Moon

D.D. Harriman is a billionaire with a dream: the dream of Space for All Mankind. The method? Anything that works. Maybe, in fact, Harriman goes too far.

But he will give us the stars...

Orphans of the Sky

Hugh had been taught that, according to the sacred writings, the Ship was on a voyage to faraway Centaurus. But he also understood that this was allegory for a voyage to spiritual perfection. Indeed, how could the Ship move, since its miles and miles of metal corridors were all there was of creation. But then he discovered the truth....