The Cassini mission is one of the greatest scientific endeavours ever undertaken. It was launched in 1997 and after a journey of over seven years reached Saturn. It follows a complex orbit, allowing it to study each of Saturn's major moons and the famous rings, and it launched the Huygens probe which successfully landed on the methane seas of Titan.
There have been many surprising discoveries, but perhaps the most beautiful are the ice fountains of Encaladus. Continually erupting and sending ice crystals thousands of kilometres into space, they are a true wonder of the solar system, described most eloquently by Professor Brian Cox in this clip.
Here is a picture captured by Cassini that shows the astonishing scale of the fountains