Mars Global Surveyor
Mars Global Surveyor was the first successful U.S. mission launched to Mars since the Viking mission in 1976. After a 20-year absence at the planet, Mars Global Surveyor ushered in a new era of Mars exploration with its five science investigations. Mars Global Surveyor arrived at Mars on September 11, 1997 (September 12, UTC), and has contributed a multitude of findings, including signs of past, persistent water such as an ancient delta and currently active water features in the gullies of canyon walls. After nearly a decade of discovery, MGS went silent in November, 2006.