Many others' comments focus on palindromes, suggesting cycles in the tracks' sequence.
The track, and therefore the album begins with a short trumpet vignette. In the Bible, the Book of Revelation says that the end of times - the apocalypse - would be heralded with the sounding of trumpets. This fits in with the themes and motifs of the album.
Gemini was an American spaceflight program from 1962-1966. 
Gemini is a subcritical nuclear test project ran by The National Nuclear Security Agency (NNSA). The NNSA runs the U.S. nuclear warhead program. 
Gemini (♊) is also the third astrological sign in the Zodiac. Gemini were twin brothers, and therefore, could be a symbolic reference to the Sandison brothers themselves, even though they are not identical.
Gemini can be also a direct reference to Gemini Films, a film production and distributor.  The duo already made a small reference to them, when they sampled the ending of the 1982 adult film titled "A Brief Affair"  on One Very Important Thought.