Slingshot orbit
From Tardis Wiki, the free Doctor Who reference
A slingshot orbit was a manoeuvre used by spacecraft in order to increase their speed. To perform a slingshot orbit, a craft would circle the orbit of a celestial body with gravity, using this to gain speed before propelling itself away.
The colony ship Heart performed a slingshot orbit around the moon in the early stage of its journey towards Centauri-Beta. (PROSE: Total Eclipse of the Heart)
