During the first season of Star Trek: Discovery, we had a chance to see a schematical view of a Constitution-class vessel USS Defiant, and later "space view" of the USS Enterprise, a starship of the same class.

Is there an in-universe explanation for the differences between the ships? They should both be from the same time, of the same class, and yet the differences are significant. The Defiant looks like it could look like this in the mirror universe, however, in the episode "Despite Yourself", which does take place in the mirror universe, there is this dialogue, which suggests that the Defiant is indeed from "our" universe:

Lorca: Data from rebel intelligence suggests that we're not the first ship from our universe to find ourselves here. It cites another Starfleet vessel: USS Defiant.


Burnham: It's unclear, but data suggests that in the future, Defiant will encounter a phenomenon that'll bring it into this alternative universe's past.

Comparison of USS Defiant (top) and USS Enterprise (bottom)

  • 5
    What are the significant differences you're referring to?
    – Valorum
    Nov 14, 2018 at 14:44
  • 1
    I think they are talking about the outer rim of the saucer section in the front and the warp pod engine support pylons Valorum.
    – user76394
    Nov 14, 2018 at 14:51
  • 2
    The outer rim, the way the nacelle pylons are shaped, the thing attached to them that looks like some sort of a weapon, the the weird additional thing at the top of secondary hull.
    – Ondrej
    Nov 14, 2018 at 14:54
  • @Ondrej: Agreed with the other points, but I think the "weird additional thing at the top of the secondary hull" is actually one of the fins on top of the other warp nacelle. Mar 30, 2019 at 13:12

1 Answer 1


Those alterations appear to have happened after it came to the Mirror Universe. When you see it in the Enterprise episode, it looks like a normal Constitution class ship.

enter image description here

The Defiant has been in the Mirror Universe for 80 whatever years. It was bound to have some retro-fits and repairs, which led to it being different than original spec.

Ted Sullivan ( a writer for Star Trek Disovery) via Twitter has confirmed the differences in appearance were from the Terran Empire.

enter image description here

  • 1
    After some thought, I do not think that this is correct. Correct me if I'm wrong, but this should be the same Defiant like the one in The Tholian Web, where it was shifting between our universe and an alternate/mirror universe. So it should look the same, no?
    – Ondrej
    Nov 14, 2018 at 18:11
  • 3
    @Ondrej I'm not sure what you are saying. it is the same Defiant, but the Tholian Web sends it ~80 years into the "past" of the Mirror Universe. Just like your quote says. Nov 14, 2018 at 18:13
  • 1
    @Ondrej I added a confirmation from the writer that the changes you see are a result of it being in the Mirror Universe for so many years. Nov 14, 2018 at 18:22
  • You're right, my bad. Thanks for an excellent explanation!
    – Ondrej
    Nov 14, 2018 at 19:01

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