Five-year mission

"Space, the final frontier. These are the voyages of the starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before."
 * - James T. Kirk, opening narration to Star Trek: The Original Series.

A five-year mission of deep space exploration into uncharted space was a type of assignment given to Starfleet starships in the 23rd century.

History
One of the greatest chapters in Starfleet history was the five-year mission of the USS Enterprise (NCC-1701) from 2265-2270 under Captain James T. Kirk. 

In 2269, Captain Kirk said to Odona that the USS Enterprise carried on board enough food to feed a crew of 430 for five years. 

In the alternate reality, nearly a year after stardate 2259.55, the USS Enterprise (alternate reality), under the command of Captain, began the first five-year mission of deep space exploration into uncharted space that had ever been attempted by any starship.

Appearances

 * (Every episode except for, First appearance)
 * (Every episode)
 * (Mentioned only)
 * (Mentioned only)

Background Information
The 2265-2270 five-year mission of the USS Enterprise mission was chronicled in Star Trek: The Original Series and Star Trek: The Animated Series, based on the opening narration to those series. The Star Trek Encyclopedia and Star Trek Chronology have conjectured that Captain Robert April had one five-year mission and Captain Christopher Pike had two five-year missions with the Enterprise before Kirk assumed command. These sources also state that Kirk had a second five-year mission after.

Until 2259 in the alternate reality seen in and, a five-year mission of deep space exploration was unprecedented. Because the alternate reality was a divergent timeline that split from the original universe in 2233, there presumably had not been any official five-year missions prior to, at least, that year in the prime reality.

No references have been made to five-year missions after the 23rd century. Instead, the opening narration of Star Trek: The Next Generation refers to the Enterprise's "continuing mission". However, in 2363, the USS Olympia embarked on a similary-named eight-year mission. In an interview in the DS9 Season 3 DVD, Ira Steven Behr said that the USS Defiant (2370) was "on a five-year mission to kick ass."

Fünf-Jahres-Mission Mission quinquennale ファイブ・イヤー・ミッション