Europa has an insane giant ocean underneath it's frozen outer layer. Plus these will have been 'Golden Aged' so there will have been some terraforming done like with Mars and Venus. There's some concept art of a frozen landscape and Europa has been rumored as a destination since before launch. There's a picture of the Saturn orbit screen in one of the 'cut' content videos. The Cauldrons of Rhea are mentioned on one Grimoire screen. Also there was mention of a lost ship/fleet in orbit. This may end up being the Saturn destination. This could be quite cool.