Jim Green, director, Planetary Division, NASA's Science Mission Directorate, answers a question at a public event at NASA Headquarters observing the first anniversary of the Curiosity rover's landing on Mars, Tuesday, August 6th, 2013 in Washington. The Mars Science Laboratory mission successfully placed the one-ton Curiosity rover on the surface of Mars on Aug. 6, 2012, about 1 mile from the center of its 12-mile-long target area. Within the first eight months of a planned 23-months primary mission, Curiosity met its major science objective of finding evidence of a past environment well-suited to support microbial life. Photo Credit: (NASA/Carla Cioffi)