Tunnel in the Sky is a juvenile science fiction novel by American writer Robert A. Heinlein, published in 1955 by Scribner's as one of the Heinlein juveniles. The story describes a group of students sent on a survival test to an uninhabited planet, who soon realise they are stranded there. The themes of the work include the difficulties of growing up and the nature of man as a social animal. Plot summary The novel's setting involves a future when Malthusian overpopulation on Earth has been averted by the invention of teleportation, called the "Ramsbotham jump", which can send Earth's excess population to colonize other planets. However, the costs of operating the technology mean that colony planets remain isolated from Earth until they can produce something to justify two-way trade. Because modern technology requires a supporting infrastructure, the colonists employ technology from the American frontier era (such as horses instead of tractors; American car-manufacturers get involved in producing Conestoga wagons). Rod Walker, a high-school student, dreams of becoming a professional colonist. The final test of his Advanced Survival class involves staying alive on an unfamiliar planet for between two and ten days. Students may team up and equip themselves with whatever gear they can carry, but they are otherwise completely on their own. They are told only that the challenges are neither insurmountable nor unreasonable. (It seems that the mores prevalent at the time regard it as acceptable to expose high-school students to very concrete life danger as part of their studies; at least, Rod's parents make no objection at knowing they may never see their son again.) On test day, students walk through a Ramsbotham portal and find themselves alone on a strange planet, but reasonably close to the designated pickup point. Rod, acting on his older sister's advice, takes hunting knives and basic survival-gear, but no high-tech weaponry, on the grounds that the latter could make him overconfident. The last advice that the students receive is to "watch out for stobor". On the second day a thief ambushes Rod and knocks him unconscious. He wakes up to find all that he has left is a spare knife hidden under a bandage. In his desperate concentration on survival, he loses track of time. Eventually, he teams up with Jacqueline "Jack" Daudet, a student from another class whom he initially mistakes for a male. When she tells him that more than