Who Mourns for Adonais? - S2-E2
Revealing mistake: When Apollo first grows large, the shimmering edge of the special effects matte is visible in the sky just above his right shoulder. (00:13:35)
Who Mourns for Adonais? - S2-E2
Revealing mistake: As Apollo's head and neck appear on the screen, the neck of the black T-shirt used to mask his body is easily seen, and his shoulders are faintly visible.
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
Thank you for the info.
Movie Nut