Promethei Terra is a large, heavily cratered, geographical region in the southern part of Mars. It was named for its noticeable albedo features, which are large areas on a planet marked by a contrast in brightness. While the Greek figure Prometheus is best remembered for the theft of fire, his name has become synonymous with human striving, often at the risk of unintended consequence. Promethei Terra, for chamber orchestra, attempts to musically capture the 'brightness' of the Martian region, as well the endless struggle for knowledge. Reull Vallis is a river-like structure located in the Promethei Terra highlands. Recently, many scientists have come to believe that at some point in the Martian past, water flowed through the Reull Vallis valley. Lineated floor deposits, located in the cliffs of the valley are believed to contain glaciers of water ice. These frozen deposits are all that remain of a possible water-rich Martian past. My work for chamber orchestra navigates through several of the geographical landmarks in the Promethei Terra highlands, including the ancient Reull Vallis river. / text