Astronomy Picture of the Day . Voyager's Preview of Galileo at Ganymede . ... 27.06.1996 . ... Credit: Voyager Project , JPL , and NASA Explanation: NASA's robot spacecraft Galileo began its long voyage to Jupiter in October of 1989. ... Now in orbit around Jupiter , Galileo will make its first close flyby of Ganymede, Jupiter's (and the solar system's) largest moon at 2:29 a.m. EDT. ... This close-up color image from the Voyager 2 flyby in 1979 previews sights Galileo will see in greater detail. ...