Joe Haldeman 
Worlds Enough and Time [EPUB ebook] 
Worlds Book 3

With their homeworld in ruins, ten thousand brave colonists set out for the stars. Among them is Marianne O’Hara — who survived a baptism of cataclysmic fire to emerge as the last hope of her doomed race. But madness, mysterious deaths and irreversible sabotage threaten their mission — propelling the crippled starship Newhome blindly toward an unimaginable future, and hurtling Marianne toward an astonishing confrontation that could mean the end or the transcendent rebirth of humankind.