Destination: Void

The project has been moved to the moon, where the scientists have cloned themselves. These clones, identified with the middle name "Lon", are kept isolated and raised to believe that they are the crew of a spaceship that will colonize another planet. The spaceship will be multi-generational, needing only a crew of six, and carrying thousands of other clones in hybernation. As the original crew dies off, other clones will be awoken.

The clone crew is really just a caretaker: the ship is controlled by the disembodied human brains (known by the euphemism "Organic Mental Cores") that run the complex operations of the vessel and keep it moving in space. But the brain dies, and when the backup is awakened, it dies as well. After the third backup fails, the crew is faced with a choice: turn around, or build the computer systems that will enable the ship to continue. Their orders from the moon base are to continue at all costs; if they turn back, they will be destroyed.

The clones have been bred and carefully selected for psychological purposes to reinforce each other, as well as to provide various specialized skills. As the crew deals with their situation, they come to understand the dilemma they're in: build an artificial intelligence to carry on the mission, or die.

This is one of Herbert's more psychological novels, deeply exploring the nature of consciousness, religion, and human interaction. The crew includes a priest/psychologist, Raja Lon Flattery, who knows their real purpose, and that the breakdown of the organic brains was planned. He's aware that several ships have gone out before theirs, each one failing. He understands the nature of the test: create a high pressure environment in which brilliance may break through out of necessity, and create in the safety of the void what humans couldn't safely create on Earth.