Ganymede (moon) moon Titan, which was previously thought to have been bigger. The grooved terrain was also seen. In 1995, the "Galileo" spacecraft entered orbit around Jupiter and between 1996 and 2000 made six close flybys to explore Ganymede. These flybys are denoted G1, G2, G7, G8, G28 and G29. During the closest flyby—G2—"Galileo" passed just 264 km from the surface of Ganymede. During a G1 flyby in 1996, the Ganymedian magnetic field was discovered, while the discovery of the ocean was announced in 2001. "Galileo" transmitted a large number of spectral images and discovered several non-ice compounds on the surface of
Ganymede (moon) the entire Solar System. There is some speculation on the potential habitability of Ganymede's ocean. The existence of a liquid, iron–nickel-rich core provides a natural explanation for the intrinsic magnetic field of Ganymede detected by "Galileo" spacecraft. The convection in the liquid iron, which has high electrical conductivity, is the most reasonable model of magnetic field generation. The density of the core is 5.5–6 g/cm and the silicate mantle is 3.4–3.6 g/cm. The radius of this core may be up to 500 km. The temperature in the core of Ganymede is probably 1500–1700 K and pressure up to . In