The science fiction novel by author Tom Godwin was first published in 1958 under the title The Survivors. It was later published in 1960 under the title Space Prison. The novel is an expansion of Godwin's story "Too Soon to Die" which first appeared in the magazine Venture.

A ship heading from Earth to Athena, a planet 500 light years away, is suddenly attacked by the Gerns, an alien empire in its expansion phase. People aboard are divided by the invaders into Acceptables and Rejects. The Acceptables would become slave labor for the Gerns on Athena, and the Rejects are forced ashore on the nearest 'Earth-like' planet, called Ragnarok. The Gerns say they will return for the Rejects, but the Rejects quickly realise that that isn't going to happen...