... Prometheus [pra-MEE-thee-us] is the third of Saturn's known satellites. ... Prometheus acts as a shepherd satellite for the inner edge of Saturn's F Ring . ... Shaded Relief Map of Prometheus . This image is a shaded relief map of Prometheus, the inner F Ring Shepherd satellite of Saturn. As with all maps, it is the cartographer's interpretation and not all features are necessarily certain given the limited data available. ... This image shows Prometheus and Pandora next to Saturn's F-ring. ...