Starships I can't help you on, but with youth serum? [Waver taps his chin lightly.] In alchemy back home, chemistry's precursor, alchemists often sought out the Philosopher's Stone, the Elixir of Life, or the Great Panacea. All had to do with youth or immortality. I don't know how true that pursuit would hold here, perhaps there's more water to it than home, but I would say that'd be a decent base line to start with.