what did you learn about nassa's cassini mission?

Cassini has revealed too many highlights of the Saturnian sytem to list them. For me personally the main focus has been about lifting the lid on Titan. A world that proved a great disappointment for Voyager due to it's shrouding atmosphere turned out to be everything weird and wonderful predicted of it - the anti-greenhouse effect, the hydrocarbon lakes and rivers, ethane rain, vast mudflats of natural plastics hemmed by mountains made of ice, cryovolcanoes. It's a place screaming for further exploration.

The most interesting thing I learned is the true extent of the seas on Titan. Before Cassini, there was speculation that most of Titan was covered in liquid. Not so. There are only a few scattered seas.

Unfortunately we still do not know the nature of these seas, because the Huygens probe missed landing in one. Imagine seas of liquid ethane. There's nothing like it on Earth. It would have to be a prime target for the next deep space probe, and would surely be vastly more interesting than yet more boring pictures of dust and craters.

Cheers!

Mainly about the hexagon, which was apparently discovered by the Voyagers though, and Titan and Enceladus.