Tor, Jul 2001, 24.95, 352 pp.
In one catastrophic hit, four billion years of evolution and growth are erased. A century has passed since the asteroid crashed into earth eradicating just about every living creature on the planet. The only human survivors are clones from long dead parents who live in Tycho Station, a dome with tunnels on the moon.
Each subsequent lunar generation understands the prime goal is to return...