From inside front cover:

EXILES from a world devastated by fear and political strife. HEROES who first must conquer their own conflicts before the greater goal can be won. PIONEERS, hundreds of men and women chosen to seek a new future, to chart a new destiny. They soared to the heart of a comet, led by three remarkable and very human people:

CARD OSBORN:
The troubled leader of an increasingly improbable mission. Silently, he calls upon his bottomless strength to carry the weight of hundreds of frightened, tormented lives.

SAUL LINTZ:
The brilliant biologist who works feverishly to heal the stricken crew. Ultimately, he undertakes a desperate experiment to delve into the very essence of life -- and death.

VIRGINIA HERBERT:
The gifted cybernetics technician, the woman both men love. She breaks the barrier of artificial intelligence and must now ho one step beyond into a melding of mind and machine.