Sagittarius role, after the introspection of Scorpio is to take the hard won wisdom and create something worthwhile from it and spread it around.
Ganymede, and four other moons dwelling in our Sun's family, possess liquid water beneath their frigid crusts of ice. The others are Saturn's moons, Titan and Enceladus, and two other Galilean moons of Jupiter--Europa and Callisto. Planetary scientists think the oceans of Europa and Enceladus are in contact with rock--thus making these two moons high-priority targets for future astrobiology missions.
Astronomers are still debating Titan's origin. However, its intriguing atmosphere does provide a hint. Several instruments aboard the Huygens spacecraft measured the isotopes nitrogen-14 and nitrogen-15 in Titan's atmosphere. The instruments revealed that Titan's nitrogen isotope ratio most closely resembles that seen in comets that exist in the remote Oort Cloud--which is a sphere composed of hundreds of billions of icy comet nuclei that circle our Star at the amazing distance of between 5,000 and 100,000 AU. This shell of icy objects extends half way to the nearest star beyond our own Sun.