Mars is the fourth planet from the Sun and is named after the Roman god of war. It has an average distance from the Sun of 230 million km and an orbital period of 687 Earth days. Past missions include the first successful flybys by Mariner 4 in 1965 and the first orbiter, Mariner 9, in 1971. Current missions include the Mars Reconnaissance Orbiter which arrived in 2006 to map terrain and weather to identify landing sites, and the Dawn spacecraft which flew by Mars in 2009 on its way to study Vesta and Ceres.