A penal deportation vessel was a type of craft that exiled criminals to a location other than that which they originated from. In 2267, Spock rebutted James T. Kirk's thought that the SS Botany Bay might be a penal deportation vessel. He felt that given the chaos of the time, it would be inefficient to waste such a spaceship for that purpose. When Kirk asked him for an alternate theory, he replied that, lacking any facts, he could not come up with one. (TOS: "Space Seed" )