Steve Chesley, Stardust NExT co-investigator, the Jet Propulsion Laboratory, holds up a model of Comet Tempel 1 during a news briefing, Wednesday, Jan. 19, 2011, at NASA Headquarters in Washington. On Feb. 14, 2011 NASA's Stardust-NExT (New Exploration of Tempel 1) mission will encounter Comet Tempel 1, providing a unique opportunity to measure the dust properties which will also provide a comparison between two observations of a single comet, Tempel 1, taken before and after a single orbital pass around the sun. Photo Credit: (NASA/Paul E. Alers)