A temporal compensator was a device invented in 2376 by a species native to a unique planet in the Delta Quadrant possessed of a tachyon core, for use in overcoming the natural temporal differential between the planet and the surrounding space.
Due to the powerful temporal field produced by the planet's tachyon core, for every 1.03 seconds which passed in normal space, nearly a day was experienced on the planet. When two astronauts boarded the USS Voyager, which had become trapped in the surrounding tachyon field, they found that their physiologies had a difficult time adjusting to the differential, and Tureena, the commander of the mission, died as a result. Gotana-Retz, the pilot, subsequently returned to the surface and, after approximately one-and-a-half years, returned with the compensator, which allowed him to exist in Voyager's time frame without actually leaving his own, but only for a few minutes. After assisting the Voyager crew in leaving orbit of the planet, Gotana said his goodbyes, and watched Voyager leave from the surface, an old man. (VOY: "Blink of an Eye")