Orphans of the Sky is a science fiction novel by American writer Robert A. Heinlein, consisting of two parts: "Universe" and its sequel, "Common Sense". The two novellas were first published together in book form in 1963. "Universe" was also published separately in 1951 as a 10¢ Dell paperback. The work presents one of the earliest fictional depictions of a generation ship.

The Future History is a series of stories created by Robert A. Heinlein. It describes a projected future of the human race from the middle of the 20th century through the early 23rd century. The term Future History was coined by John W. Campbell Jr. in the February 1941 issue of Astounding Science Fiction. Campbell published an early draft of Heinlein's chart of the series in the May 1941 issue.