Tomorrow is Yesterday - S1-E20
Visible crew/equipment: As Spock gives his report to Kirk on the bridge, the shadow of the boom mic is over his right shoulder. (00:03:35)
Tomorrow is Yesterday - S1-E20
Visible crew/equipment: When Kirk hears the audio for the first manned moon shot, he gets up to walk over to Spock. As the camera pans to follow, the shadow of the boom mic can be seen moving quickly above and to the left of his head.
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