"Vector to the Heavens" is approximately three minutes and fifty-one seconds long[KH Days], and five minutes and thirty-five seconds long in the piano collections version. Regardless of the source, the piece has a time signature of 4/4 time. The original in-game version plays at a tempo of
98 beats per minute for the introduction and first phrase, 160 beats per minute for the second phrase, and 83 beats per minute for the third phrase. The instrumentation for both the original version and the HD remake are piano and strings.
The piece is characterized by a moving sixteenth note pattern in the left hand (piano version) or moving eighth notes (in-game version). The main melody's rhythm is a variation of "Musique pour la tristesse de Xion", incorporating various parts of the theme into this piece. Several measures of this piece features the melody from Kairi's theme and Dearly Beloved. Unlike Xion's original theme, "Vector the Heavens" is played in the upper spectrum of dynamics, with the "louder" dynamics more in use than the softer ones.