Star Trek

What Are Little Girls Made Of? - S1-E7

Question: When the Enterprise is in orbit, it uses the Impulse engines to maintain orbit. The Impulse engines are located on the back (aft) of the primary saucer. Why were these not on or lit up? Unless they're using gravity, but there are the familiar engine sounds.

Movie Nut

Chosen answer: If they're in orbit, they're being pulled along by the planet's gravity well, therefore, impulse engines would only be used for minor corrections and would be "on standby" while in orbit, but not active. (Like keeping your car idling without revving the engine and creating plumes of exhaust).

Captain Defenestrator