Robinson's latest (The Great Divide, 1982, etc.) is a work of wholehearted sf that, while never expanding on the traditional elements of the genre, does a commendable job of using its strengths in an engaging story laced with genuine scientific and philosophical speculations. After a near-fatal accident, young tech assistant Sparrow awakens aboard the aging starship Astron with severe amnesia. The Astron has been exploring the galaxy for 2000 years, searching without success for any signs of alien life. As Sparrow struggles to rediscover his identity and reestablish friendships among the crew, he learns that a mutiny is brewing--the captain determines to cross the empty Dark to continue the search on the other side, but many in the crew fear the ship will never survive the journey and want to turn back toward Earth. Courted by both sides, Sparrow quickly realizes that something hidden in his memory will prove the key in the conflict. Sparrow's vacillation between loyalty and mutiny leads to interesting discussions of the likelihood of alien life in the universe, and Robinson presents convincing arguments for and against the possibility. But the true strength of the novel lies in its focus on the human element. Amid all the trappings of large- scale sf, Sparrow's inner turmoil, along with the characters of the other crew members, is consistently presented with insight and compassion.