A “remarkably young” ocean may be hiding beneath the icy cratered surface of Saturn’s “Death Star” moon – making it “a prime candidate” for studying the origins of life, scientists have said. Astronomers believe liquid water formed on Mimas – the planet’s smallest and innermost moon – somewhere between five to 15 million years ago, making it much younger than Earth’s oceans which are thought to be more than four billion years old. Mimas is often compared to the Death Star from the Star Wars franchise because of its large Herschel Crater, which resembles the hollowed-out shape of the fictional space station’s laser weapon. But with no signs of any activity, this small moon – around 400 kilometres in diameter – would have been the last place to find a global ocean beneath its surface. However, the researchers said that contrary to all expectations, Mimas appears to have an ocean just 20 to 30km below its icy outer shell. It joins a family of satellites believed to have oceans beneath their surfaces: Jupiter’s Europa and Ganymede, and Saturn’s Titan and Enceladus. Dr Nick Cooper, honorary research fellow at Queen Mary University of London, said: “Mimas is a small moon, only about 400 kilometres in diameter, and its heavily cratered surface gave no hint of the hidden ocean beneath.