final frontier

poetic slang

(poetic, slang) Synonym of outer space

Japanese Meaning

宇宙空間（未知の領域） / 外宇宙

After years of study, the crew finally felt ready to voyage into the final frontier.

何年もの研究の末、乗組員はついに宇宙へ航行する準備が整ったと感じた。

Sense（1）

(poetic, slang) Synonym of outer space

Space may be the final frontier and it’s starting to get awfully crowded.