The first convincing evidence of liquid water on a comet comes from analysis of a sample of Comet Wild-2, returned to Earth by NASA’s Stardust space mission.
The moon is our closest neighbor in space, but today two asteroids come closer. One passed through the Earth/moon system this morning - and the other minutes ago.
NASA talks about the legacy of space shuttle Discovery, piloting the mission that launched the Hubble Space telescope, and what's next for human spaceflight.
On Thursday, March 17, 2011, the MESSENGER spacecraft will become the first space probe to enter orbit around the innermost planet of our solar system, Mercury.