Time machine
The old guy, who is inhabited by the spirit of Lux, wants the time machine to get back into his rock star body. He either can't go back to another body on his own, or he simply doesn't know where the body is
If he were to succeed in going back in time, he'd have enough time to prevent the black wing project too, effectively allowing Bart to become semi-normal albeit hypersensitive person, but definitely disinterested in killing Dirk...
And keeping up with a 3?1! theme, it would also "save her", as in, not Lydia, but Lydia's mom
___
Anyone who has ever read any spoilers,
knows that Winter Is Coming