Trivia: The costume of the Salt Vampire from "The Man Trap" appears in Trelane's castle. It is in an alcove near the front door.
Trivia: William Campbell later appeared as Klingon captain Koloth in "The Trouble With Tribbles."
Trivia: Interestingly, Trelane put Kirk on trial in his courtroom. In Star Trek: The Next Generation S1 : Ep1 "Encounter at Farpoint", Q played judge in an apocalyptic courtroom, putting Picard and the human race on trial.
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