The Rolling Stones
Robert A. Heinlein
 The Stones, a family of "Loonies" (residents of the Moon, known as "Luna" in Latin), purchase and rebuild a used spaceship, and go sightseeing around the solar system. The twin teenage boys, Castor and Pollux, buy used bicycles to sell on Mars, their first stop, where they run afoul of import regulations and are freed by their grandmother Hazel Stone. While on Mars, the twins buy their brother Buster a native Martian creature called a flat cat, born pregnant and producing a soothing vibration, as a pet. In the Asteroid Belt, where the equivalent of a gold rush is in progress prospecting for radioactive ores, the twins obtain supplies and luxury goods, on grounds that shopkeepers are much likelier to be rich than miners. En route, the flat cat and its offspring overpopulate the ship, so that the family place them in hibernation, and later sell them to the miners. Subsequently, the family set out to see the rings.