Scientists are wading through a trove of data from Saturn and its moons thanks to the discoveries of the Cassini spacecraft, which was intentionally plunged into Saturn's atmosphere in September. Launched in 1997, Cassini reached the Saturn system in 2004 after gravitationally slingshotting around Venus, Earth, and Jupiter. The spacecraft's 12 instruments collected data that revealed oceans of liquid methane on the surface of Titan, Saturn's largest moon, and helped scientists measure the length of a Saturn day, a long-standing mystery.
In 2005, Cassini's car-sized lander probe, called Huygens, touched down on the surface of Titan and returned images of the freezing world's hazy atmosphere, icy pebbles, and highlands permeated with drainage channels. Cassini continued to orbit Saturn for years — revealing new mysteries such as a 10-kilometer ridge circling the equator of the moon Iapetus — but its fuel supplies were dwindling. In April 2017, the spacecraft began a series of 22 plunging orbits between Saturn and its rings, a "Grand Finale" for the 20-year-old Cassini. These orbits, each lasting roughly 7 days, revealed never-before-seen details of the gas giant's atmosphere, clouds, and ring system.
On September 15th, Cassini dove into Saturn's thick atmosphere, an intentional death knell. The plunge was intended to prevent the spacecraft from contaminating either Titan or Enceladus, moons believed to be potentially habitable. After traveling for nearly 8 billion kilometers, collecting almost half a million images, and beaming back data used in over 3,900 scientific studies, Cassini has bid us farewell.