For a significant portion of the film – as Kit explores the terrain with no other life to communicate with (except for his monkey, Mona) – Nathan Van Cleave s music takes center stage. Van Cleave s themes are simultaneously foreboding and triumphant. Only a few short years before Planet of the Apes took science fiction to its inevitable dystopian ends, the soundtrack to Robinson Crusoe on Mars is a pure patriotic time capsule; the sounds of a retro-future when science fiction films were still produced with true optimistic sincerity.