From left to right: The mosaic and geologic maps of Jupiter’s moon Ganymede were assembled incorporating the best available imagery from NASA’s Voyager 1 and 2 spacecraft and NASA’s Galileo spacecraft. Credits: USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech. The first of the gas-giant orbiter’s back-to-back flybys will provide a close encounter with the massive moon after over 20 years. On Monday, June 7, at 10:35 a.m. Pacific Time, NASA’s Juno spacecraft will come within 645 miles of the surface of Jupiter’s largest moon, Ganymede. The flyby will be the closest a spacecraft has come to the solar system’s largest natural satellite since NASA’s Galileo spacecraft made its penultimate close approach back on May 20, 2000.