Of the many common classes of vessels in Starfleet (Excelsior, Constitution, Galaxy, Defiant, etc.) how long were ships expected to be in service? I understand that throughout the course of their usage, many ships end up being destroyed for various reasons and this was certainly the case for many of the Enterprises throughout the course of the progression of history in the Star Trek universe.

However, assuming that many of these ships hand never encountered a circumstance capable of utterly destroying a vessel, how long did Starfleet expect their vessels to last before being decommissioned?

  • 2
    The "bonus" isn't necessary and it asked just in case the answerer already knows the question. Yes, I could split this out, but this isn't uncommon in SE.
    – RLH
    Jun 17, 2016 at 19:06
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    The USS Hathaway (TNG: Peak Performance) is a perfect example of a (80+ year old) ship that was kept in mothballs for use in a training exercise; memory-alpha.wikia.com/wiki/USS_Hathaway.
    – Valorum
    Jun 17, 2016 at 19:16
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    In the time of STIII - Search for Spock, Admiral Morrow says "Jim, the Enterprise is twenty years old. We feel her day is over." - aside from whether or not that even was accurate, he feels 20 yrs is the expiration date. Later by TNG and DS9, we still see Miranda class (like the Reliant) all over the place.
    – NKCampbell
    Jun 17, 2016 at 19:54
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    It's also pretty likely that different ship classes were expected to serve different periods of time. Something like a constitution class, with high workload and experimental tech, might only be competitive with adversaries for 20 years, but a science or transport ship might fulfill its mission for much longer.
    – nexus_2006
    Jun 17, 2016 at 20:04
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    @Valorum That's my point. It's a good question on its own... it should be given the chance to be asked and answered without being tied to this question.
    – Catija
    Jun 17, 2016 at 20:17

5 Answers 5


Galaxy class: 100 years

This answer concerns the Galaxy class of starships. According to the first chapter of the Star Trek: The Next Generation Technical Manual (prepared by TNG production designers Mike Okuda and Rick Sternbach):

Spaceframe design life of approximately one hundred years, assuming approximately five major shipwide system swapouts and upgrades at average intervals of twenty years. Such upgrades help insure the continuing usefulness of the ship even though significant advances in technology are anticipated during that time. Minor refurbishment and upgrade to occur at approximately one- to five-year intervals, depending on specific mission requirements and hardware availability.

This gives a fairly precise idea of how long Starfleet expects a Galaxy class ship to last — assuming it does not meet some terrible fate along the way — and how they expect it to reach that ripe old age (i.e. through maintenance, swapouts, and upgrades at prescribed intervals).


Constitution Class: Roughly 50 years

There doesn't seem to be much in-universe agreement on the Constitution class lifespan (TOS ship, not counting the Abrams reboot). In Star Trek III there's Scene 43

SCOTTY: With all appreciation, sir, I'd prefer to supervise the refit of Enterprise.

MORROW: Yes, well... That really won't be necessary...

SCOTTY: But sir -- this refit will take a practiced hand. There's much to do --
(a look at Kirk)
It could be months.

MORROW: No, Mr. Scott, I'm sorry... There isn't going to be a refit.

KIRK: Admiral, I don't understand. The Enterprise --

MORROW: Jim, the Enterprise is twenty years old. We think her day is over...

Nobody really was all that concerned with canon dates at the time (the Enterprise herself was launched in 2245 and STIII took place in 2285), but the 20 year timeframe doesn't fit within TOS, so the dates are kinda timey-wimey. Maybe he means the Enterprise is 20 years beyond retirement. Maybe he's just making an excuse to not refit a battle damaged ship. We know that the Enterprise-A was in service in 2293(STVI), but scheduled to be retired. The Enterprise-B was commissioned later that same year.

Assuming the same hull was used throughout (the original ship was destroyed in STII and we don't know enough about the refit ship), that would give a Constitution class a lifespan of roughly 50 years (48 from 2245 to 2293).



The first Excelsior class starship, the Excelsior itself, was seen in Star Trek III, Star Trek IV, and Star Trek VI. Its service life lasted longer than the entire service life of the Enterprise NCC 1707-A (at least its entire service life with the designation of Enterprise NCC 1707-A since it might originally have had a different name and number).

A number of Excelsior class starships appeared in Star Trek: The Next Generation, DS9, and even in "Endgame", the last episode of Voyager. According to the official chronology that is from 2283 to 2378, or 95 years.

Of course individual Excelsior class starships may have served for far less than 95 years. The Excelsior class starship USS Repulse was seen in 2365 ("The Child") and mentioned on more or less readable screens as late as 2374 ("In the Pale Moonlight"). Its register number of NCC 2544 is only 544 digits higher than the NCC 2000 of the original Excelsior, but many other starships operating in the next Generation era had register numbers tens of thousands of digits higher, thus implying that the Repulse should be almost as old as the Excelsior.

So many persons may interpret the data as indicating that Excelsior class starships sometimes serve for 70 or 80 years.


NX Class: 10 years

The Enterprise NX-01 was launched in 2151 (ENT 'Broken Bow') and was decommissioned in 2161 (ENT 'These Are The Voyages...'). This is the best guess we can make, as we have very little knowledge of the happenings between the end of ENT and the start of TOS.


Daedalus class: 35 years

This is speculation on Memory Alpha, but nonetheless reasonable. We know that the NX-class was decommissioned in 2161. We also know that at that point Warp 7 ships were being released.

We also know from TNG 'Power Play' that the Daedalus class was not in service for 172 years prior to that episode. That episode took place in 2368 (source). So the Daedalus class was decommissioned in 2196.

Hence, it's not unreasonable to suppose that the Daedalus class was the class that replaced the NX class. If so, we can expect they would have expected to serve for about 35 years.

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