“The psychological aspect is a really important one to deal with, because if it’s done right, the missions can be truly amazing,” says Buckey. “But if it goes wrong, it’s the kind of thing that can end a mission.”https://www.bbc.com/future/article/20191029-how-long-space-voyages-could-mess-with-our-minds
What would a person do once Earth is no longer viewable? How long before some serious psychological problems would affect them?
Star Trek: TNG had it right. We definitely need a holodeck (or at least mandatory VR headset time). Hmm. Good thing I already included this in my SF story… (watch this space!)