Just curious if anyone knows why the Federation left the Cardassian systems intact on DS9...

For Starfleet staff on the station, learning an entirely new system would be incredibly difficult; not to mention that it wouldn't be compatible with other interfacing Starfleet vessels.

From a TV production point of view, I'm not sure why the producers didn't simply retcon parts from TNG and VOY and use them, rather than building Cardassian parts from scratch.

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    In some cases they did. In one of the episodes O'Brien laments about how challenging it is to keep the Cardassian and Federation systems working together.
    – Xantec
    Oct 23, 2017 at 19:58
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    On another note, instead of replacing every single system they might as well have built a new one in terms of the labor required.
    – Hans Olo
    Oct 23, 2017 at 20:00
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    in the first episode O'Brien notes that the Cardassians took 'every component of value'. Out of universe: Voyager didn't exist yet when DS9 was starting production and they wanted to make a clear distinction between TNG and the new show. Hard to make that case when the sets still looks like 80s Space Hilton
    – NKCampbell
    Oct 23, 2017 at 20:03
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    there's a good answer here that I hadn't thought of: reddit.com/r/startrek/comments/1otx3t/… - namely, it wasn't Starfleet's station to go retrofitting all over the place - it was Bajoran, many Bajorans might be more likely to know Cardassian tech than Starfleet, etc
    – NKCampbell
    Oct 23, 2017 at 20:06
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    The alien systems were more advanced. They even had a spin-off show about it, "Keeping up with the Cardassians".
    – Paul
    Oct 25, 2017 at 1:06

3 Answers 3


There are a few reasons we can intuit.

  1. DS9 isn't a Federation starbase, it's technically Bajoran. Starfleet was focused on getting it to work, and only replaced the essential systems. They weren't even planning (as far as we can tell) on upgrading the shield/weapons until a major threat manifested itself.
  2. Bajorans are likely to be more familiar with Cardassian interfaces than Federation LCARS. So even with a Federation administrative presence, keeping the original interfaces made sense for the owners benefit. This applies to both Ops (Kira, Odo) and civilian (Quark, Garak) users.
  3. The cost (in an industrial sense) probably outweighed the benefit. We only see the crew having problems early on (O'Brien's first use of the Transporter). While the physical systems continue to have problems, the main characters do not have any issue using the interfaces after a short adjustment period. That adjustment is probably cheaper/easier than replacing all of the control terminals across the entire station, as well as the main computer.
  4. It might not even be possible. If the Cardassian computer (and associated terminals/interfaces) is specialized enough, it may not be possible to set up a Federation computer core that could properly control all of the systems installed on DS9 without spending more time/resources than building a new starbase. We're talking everything from Transporters, to Door Control, to the Fusion Reactor.

Conjecturally, it is possible that the Cardassian interface actually isn't that different from Federation LCARS. The color palette is different, and the layout might be strange, but it doesn't appear to be any worse than switching from Android to iOS in our world. The functions are all there, they just might be in a different menu or have a different name.

Out of Universe/Behind the Scenes

Since you also asked

From a TV production point of view, I'm not sure why the producers didn't simply retcon parts from TNG and VOY and use them, rather than building Cardassian parts from scratch.

DS9 ran concurrently with TNG for a couple seasons, so they couldn't recycle any sets besides occasionally "borrowing" them: Such as the pilot episode having scenes on the Enterprise, or TNG using the Runabout set. The production had to build new sets and props either way.

One big reason for designing new Cardassian equipment and sets was to give the show a visibly different aesthetic. They wanted it to stand out, since they weren't the only Star Trek show on TV.

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    A perfect answer, thank you for the thorough explanation. Oct 23, 2017 at 21:28
  • Thanks, though I'm missing some quotations that would support this, which Valorum supplied in their answer below.
    – ench
    Oct 23, 2017 at 22:08
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    @FrankCedeno We don't get any specific mention of Cardassia draining any resources from the Federation. O'brien refers to the prior conflict as "The Border Wars", which seems to indicate it was comparatively small scale. The Cardassians only seemed to be a threat to planets near the border.
    – ench
    Oct 24, 2017 at 18:24
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    In general, Star Trek folk seem to have an almost absurd ability to quickly figure out how to use any computer or or starship interface. The fact that a system was designed by members of another race that's culturally different or isolated from the Federation, and even from a distant quadrant, is rarely an obstacle. I recall few exceptions. Given this ease with alien systems, why bother replacing the Cardassian interfaces? (The differences should be more like the difference between Latin-alphabet languages and Chinese if programmers have no reason to try to match other races' expectations.)
    – Mars
    Oct 25, 2017 at 4:13
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    Or analogous to the difference between contemporary mouse-based interfaces, and Unix or DOS/CMD shell commands. Or between Fortran, Java, Common Lisp, Haskell, and APL. (Sorry, my other nerdy dimension is leaking into this one. I know this comment won't be intelligible to everyone.)
    – Mars
    Oct 25, 2017 at 4:20

They were replacing the Cardassian components. Or if they couldn't replace them, at least making sure that they conformed to Federation standards.

ILORA: But these relays don't have nearly as much carrying capacity as before. They won't be able to handle the signal load from the transceiver.

O'BRIEN: Well, in order to bring the system up to Starfleet code, I had to take out the couplings to make room for a secondary backup.

GILORA: Starfleet code requires a second backup?

O'BRIEN: In case the first backup fails.

GILORA: What are the chances that both a primary system and its backup would fail at the same time?

O'BRIEN: It's very unlikely, but in a crunch I wouldn't like to be caught without a second backup.

DS9: Destiny.

As to why they didn't tackle the computer as a priority, the short answer is that it's a very big job and one that would take O'Brien and his engineers years to accomplish, assuming they don't want to turn off the station while they do the work.

O'BRIEN: Fine? With all due respect, Commander, as an engineer, I couldn't look at myself in the mirror if I allowed this computer to perform as it is now. I'll have to do a root canal.

SISKO: Root canal?

O'BRIEN: It's engineering shorthand, sir. I'll have to get into its guts and rebuild her from the ground up.

SISKO: How long will that take?

O'BRIEN: Well, I'm still not that familiar with Cardassian technology but I'd guess no more than two, three years.

DS9: The Forsaken

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    This is the better answer, since they actually were working to replace the systems. From my recollection, fixing/ updating/ replacing things was pretty prevalent towards the first season and then fell off for the most part, but I'm pretty sure there was an episode somewhere where left-over systems that were compromised/ sabotaged caused some problems.
    – RIanGillis
    Oct 24, 2017 at 5:20
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    @RIanGillis and it is actually repairs (or at least inspections) of such systems which trigger the issues in several episodes (e.g. Babel or Civil Defense) Oct 24, 2017 at 14:03

For a real-world answer:

According to the contemporary book 'The Making of Star Trek: Deep Space Nine' by Judith and Garfield Reeves-Stevens, in a section dealing with the evolving early production design on the show (Chapter Eleven), a memo from scenic artist Michael Okuda to series creators Rick Berman and Michael Piller, dated 21 May 1992, is printed, on p 170 - 172, in which the question is brought up:

We are rapidly approaching the point where we still need to address the question of whether or not our heroes can read the Cardassian language. This is important [...] as it affects the design of consoles and readouts.

Okuda is here opening a discussion about whether the set design should be an all-alien environment, or one which incorporates elements of alien equipment jury-rigged with Starfleet designs? The choice would be important to establishing the show's visual identity.

Okuda goes on to write, in favour of an all-Cardassian look, that he feels:

[...] it would be visually fun. Having a more alien style to the hardware and readouts would be more interesting visually, and would help to distinguish the two Star Treks from each other.

This is a key point, made alongside the story-telling possibilities of having a station where the human crew may have to figure out ways to make the equipment function like starfleet vessels. Okuda then goes on to offer several alternative ways this may be approached, including some kind of visual Cardassian-to-English translation on the screens, having the characters simply verbally translate for the audience, or going the route of having very alien set designs that gradually show more Starfleet tech over time as the crew gradually update the station, until it is a mesh of both.

The production crew ultimately made the choice to visually separate the new show from the old as much as possible, something which informed choices on designing new Starfleet uniforms as well, so as to keep the two co-current Star Trek TV shows as visually diverse from each other as possible.

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