A Constitution-class starship found orbiting Omega IV in 2268 with its crew dead and only its captain alive on the planet below.
The USS Exeter was a Constitution-class starship commanded by Captain Ronald Tracey. In 2268 the Enterprise found it orbiting Omega IV with its crew dead, reduced to crystals by a disease that a landing party had carried back from the planet.
Tracey, the lone survivor, had violated the Prime Directive on the surface, using his phaser to help the Kohms against the Yangs in the belief that the planet held a secret of long life. Kirk's landing party learned they had become immune through their exposure, and Kirk exposed Tracey's interference and stopped him.