Spoiler warning: Plot and/or ending details follow.
Prior to his assignment onboard the Enterprise, Faust had been assigned to the research vessel Pretorius.
In 2270, Faust was part of a landing party on Baldur III that helped to evacuate the civilians when the warp core Thunderbird was on the verge of breaching. With the rescue successful, Faust manned the science station in lieu of Commander Spock's abscence. He reported that the firing of the ship's phasers, to prevent a fire from ravaging Jackpot City, had no appreciable in regards to the fire expanding. (TOS novel: The Antares Maelstrom)