I think that by the end of the series that getting home would have been a hope that had been abandoned. As the series went on the character's links to Earth were eroding, while their ties to each other were getting stronger and the profundity of the mission was starting to dawn on them. I think the AU flashbacks in Twin Destinies
were especially telling. Chloe vowed to stay without even looking to see what Scott was doing, and Volker (who was going insane on the ship earlier on) almost looked like he had just had an epiphany, and was the second to volunteer.